Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components
  • G03G9/132—Developers with toner particles in liquid developer mixtures characterised by polymer components obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G9/00—Developers
  • G03G9/08—Developers with toner particles
  • G03G9/12—Developers with toner particles in liquid developer mixtures
  • G03G9/13—Developers with toner particles in liquid developer mixtures characterised by polymer components
  • G03G9/131—Developers with toner particles in liquid developer mixtures characterised by polymer components obtained by reactions only involving carbon-to-carbon unsaturated bonds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/001—Electric or magnetic imagery, e.g., xerography, electrography, magnetography, etc. Process, composition, or product
  • Y10S430/105—Polymer in developer

Definitions

• the present invention relates to electrophotography, and more particularly to improvements in the developpatterns and to liquid dc-
• Known electrophotographic processes comprise the 'steps'of electrostatically charging in the dark a photoconductive surface, image-wise exposing the said surface whereby the irradiated areas become discharged in accordance with the intensity of radiation, thus forming a latent electrostatic image and developing the material to form a visible image by depositing on the image a finely divided 'electroscopic material known as toner.
• the thus developed image may be fixed to the surface of the photoconductor or transferred to another surface and fixed thereon.
• the latent electrostatic image is developed or rendered visible by use of liquid developers comprising coloured toner particles suspended in an insulating carrier liquid, which should have a volume resistivity in excess of IO Ohm.cm and a dielectric constant below 3.
• the suspended toner particles usually finely divided pigments or dyes, are elec- I trostatically charged and develop the latent image under influence of the charge of the latent electrostatic image.
• a negative-working developer contains toner particles which are attracted by positive electrostatic charges, or which upon contact with a surface bearing latent image areas formed by negative electrostatic charges are repelled by such negative charges and deposit onto the non-image areas.
• a positive working developer behaves in the reverse sense and thus contains particles which are attracted by negative electrostatic charges. 7
• Electrophotographic coatings containing zinc oxide are generally charged negatively with the result that the latent image formed by exposure is negative in polarity.
• a positive developer can be applied to a zinc oxide layer containing a negative latent image to produce a facsimile reproduction of the original radiation patternwhereas a negative developer can be applied to such layer to produce areversal reproduction of the original radiation pattern.
• the polarity of the toner particles with respect to the electrostatic latent image to be developed is determined by the nature of the materials used in the preparation of the liquid developer and by so-called polarity control agents, which confer to the suspended toner particles either a negative or positive charge.
• alkylated polymers of heterocyclic N-vinyl monomers induce in liquid to'ner compositions strong negative polarity on the suspended toner particles.
• These polymeric materials are preferably materialsobtained by alkylation of homopolymers or copolymers of a N-vinyl lactam monomer, most preferably a N-vinyl pyrrolidone monomer with an a-olefin containing from 2 to 2000 carbon atoms, or obtained by simultaneously polymerizing and alkylating a mixture containing a heterocyclic N-vinyl monomer and an a-olefin.
• alkylated polymers of heterocyclic N-vinyl monomers give excellentdevelopers of positive polarity when the toner particles are suspended in an insulating liquid and the said toner particles are overcoated with a resin.
• the present invention thus provides a positiveworking electrostatic liquid developing composition
• a positiveworking electrostatic liquid developing composition comprising an electrically insulating carrier liquid having a dielectric constant of less than 3 and a volume resistivity in excess of 10 Ohm.cm, resin-coated toner particles suspended in said carrier liquid and an alkylated polymer of a heterocyclic N-vinyl monomer.
• Resin-coated toner particles are widely known in the art of liquid electrostatic developers.
• the resin functions as fixing agent to fix the toner particles where they are deposited e'lectrostatically.
• Examples of resins that can be used in accordance with the present invention are esters of hydrogenated rosin and longoil, rosin-modified phenol formaldehyde resins, pentaerythritol esters of rosin, glycerol esters of hydrogenated rosin, short oil and medium oil alkyd resins, polyvinyl esters e.g. polyvinyl stearate, coumarone-indene resins, polyacrylates and polymethacrylates, e.g.
• PICCOVAR 440 (trade name of the Picco Company USA) cyclized rubber e.g. ALPEX 514 of Reinhold Albert Chemie A.G., W. Germany as well as rosin and synthetic resins derived from rosin e. g.
• PENTALYN A a'pentaerythritol ester of wood rosin with acid No. 12
• PENTALYN H a pentaerythritol ester of hydrogenated wood rosin with acid No. 13
• PENTALYN X a pentaerythritol ester of hydrogenated wood rosin with acid No. 14
• POLYPALE ESTER 10 a glycerin ester of polymerized wood rosin with acid No.
• STAYBELITE ESTER 10 a glycerin ester of hydrogenated wood rosin with acid NO. 8; AMBEROL M21 and M82 (registered trade marks of the Rohm & Haas Company), which are wood rosinmodified phenol formaldehyde resins.
• suitable resins are POLYSTYRENE PS 3 marketed by Dow, LUVISKOL VA 64 of BASF, which is a co(vinylpyrrolidon-vinylacetate) (:40), POLYS- TYROL B of BASF, which is a co(styrenebutylacrylate), KYRAX A of AIRKO, USA, which is a polyvinyl stearate.
• these fixing agents need not necessarily be present as a coating'over the toner particles and may be included in the liquid composition as a separate addition. It is pointed out that when such fixing agents are added separately to the liquid composition and thus not coated on the pigment particles beforehand, the above alkylated polymers of heterocyclic N-vinyl monomers provide a negativeworking toner composition or a toner composition with both negative and positive characteristics, which is therefore unsuitable for use. Accordingly, it is surprising that an exceptionally positive-working toner composition can be provided with the above alkylated polymers of heterocyclic N-vinyl monomers when the toner particles are resin-coated.
• the positive polarity increases with the concentration of the said alkylated polymers so that the polarity can be easily controlled and an optimum relationship obtained.
• exception must be made for resincoated carbon blacks .where the amount of said a1kyl ated polymers must be limited to at most by weight relative to the amountof resin-coated carbon black since'otherwise the polarity may become reversed. As is set forth hereinafter, this maximum percentage can be higher by the presence in the developing composition of other positively polarizing agents and/orthe use of a mixture of carbon black and a colour-improving dyestuff as colouring matter that is resin-coated Resin-coated toner particles are particularly advantageous in electrophotographic multicolour reproduction processes.
• images are produced by repeating for each colour separation image the successive operations of-charging the photoconductive element, exposing to a colour image through a filter absorbing the colour to be reproduced and developing by means of toner particles of the desired colour.
• the image areas of the toner first deposited should be capable-of carrying the appropriate charge and comprise'therefore an insulating material e.g. a resin coated over the, toner deposit. It is possible forthis purpose to incorporate the insulating resins in the liquid developing composition. However, large amounts are required which reduces the intensity .of colour deposit. Improved results are obtained when in the liquid developing composition, the toner particles are overcoated with the resin.
• the resin-coated toner particles allow proper recharging of the photoconductive element.
• alkylated polymers of heterocyclic N-vinyl monomers which are used in accordance with the present invention in combination with resin-coated toner particles are preferably derived: fron N-vinyllactam monomers, mostpreferably from N-vinylpyrrolidone and N Pat. No.
• the alkylated polymers of the heterocyclic N-vinyl monomers suitable for use in accordance with the present invention can be prepared by alkylation of a homopolymer or copolymer of such heterocyclic N- vinyl monomer with an alpha-olefin containing from 2 carbon atoms to 2,000 carbon atoms, preferably in the range of from 2 to 200 carbon atoms, and most preferably in the range offrom 8 to 42 carbon atoms, said alkylation process beingmore fully described in U.S. Pat. No.
• heterocyclic N-vinyl monomers the alkylated polymer derivatives of which can be used in accordance with the present invention can be found in the above U.S. Pat. No. 3,542,681 which also includes representative examples of monoethylenically unsaturated polymerizable monomers suitable for copolymerization with the said heterocyclic N-vinyl monomers to form copolymers which are readily alkylated as described above. More details as regards the a-olefins employed for producing the alkylated polymers can also be found in the said U.S. Pat. No. 3,542,681. It can also be learned from this U.S.
• the alkylated polymers have a K-value comprised between 10 and 140, preferably between 30 and 100.
• Particularly suitable for use in accordance with the present invention are GANEX 216, GANEX 220 and ANTARON V216 which are olefin-alkylated poly-N-vinylpyrrolidone with 20 vinylpyrrolidone residue commercially available from GAF.
• the positive polarity of the resin-coated toner particles can be easily controlled. This makes possible to obtain an optimum relationship, as a function of the electrostatic latent image charge, between the developable density and the stability of the toner composition against settling of the toner particles. Moreover, it was found that the positiveworking toner compositions of the present invention are perfectly suitable for continuous-tone multicolour reproduction in that the gradation is dependent on the polarity of the toner particles; the more positive the polarity the softer the gradation that is obtained.
• a liquid'electrophotographic developer according to the present invention can contain other positively polarizing agents, e.g. metal soaps of fatty acids such as aluminium stearate, zinc stearate, lead stearate, copper stearate, cadmium stearate, calcium stearate, zinc palmitate, aluminium palmitate, lithium octoate, aluminium dresinate (aluminium salt of abietic acid), vanadium dresinate, tin dresinate, copper linoleate, manganese linoleate, etc. and the bivalent or trivalent metal salts of an oxyacid derived from phosphorus containing at least one organic residue according to British Pat. No. 1,151,141.
• metal soaps of fatty acids such as aluminium stearate, zinc stearate, lead stearate, copper stearate, cadmium stearate, calcium stearate, zinc palmitate, aluminium palmitate, lithium
• the bivalent or trivalent metal salts of a phosphorus oxyacid are preferably bivalent or trivalent metal salts of:
• the said organic group can be aliphatic, cycloaliphatic or aromatic.
• the salt comprises an organic residue e.g. organic group(s) and/or ester group(s) rendering the salt substantially soluble in the electrically insulating carrier liquid.
• the organic residue preferably comprises a chain of at least 4 carbon atoms, most preferably from 10 to 18 carbon atoms, and such chain may be substituted and/or interrupted by heteroatom(s), e.g. oxygen, sulphur, or nitrogen atom(s).
• the solubility in the electrically insulating carrier liquid of the metal salts can be promoted by the presence of one or more organic groups with branched structure, e.g. branched aliphatic groups, such as a 2-butyl-octyl group.
• magnesium salts may also be used for example magnesium salts, calcium salts, strontium salts, barium salts, iron salts, cobalt salts, nickel salts, copper salts, cadmium salts, aluminium salts, and lead salts.
• the liquid developer composition of the present invention comprises as a base fluid any of the conventional electrically insulating carrier liquids generally employed in liquid developer compositions.
• the carrier liquid includes various hydrocarbon solvents; e.g. aromatic hydrocarbons such as benzene, toluene and xylenes, aliphatic hydrocarbons such as hexane, cyclohexane and heptane; fluorocarbons and silicone oils.
• the carrier liquid is preferably a commercial petroleum distillate e.g.
• mixtures of aliphatic hydrocarbons preferably having a boiling point comprised between 150C and 220C such as the IS OPARS G, H, K and L (trade names) of the Esso Standard Oil Company, SHELL SOL T (trade name) of the Shell Oil Company, etc.
• the carrier liquid is non-polar
• The, pigment or colouring agent used as toner may be any of the pigments and dyestuffs commonlyemployed in liquid electrostatic toner compositions providedthat they carry a resin-coating.
• the colouring agent or pigment can be carbon black and various analogous forms thereof e.g. lamp black, channel black and furnace black.
• Suitable coloured pigments include azo dyes, xanthene dyes, phthalocyanine dyes, which may be in X- form e.g. as described in published German Patent (DOS) 1,944,021, triphenylmethane dyes, diphenylmethane dyes, stilbene dyes, acridine dyes, quinoline dyes, quinone imine dyes, thiazine dyes, azine dyes, etc.
• DOS German Patent
• the pigments or dyes used in accordance withthe present invention should be resincoated, which can be achieved by any suitable means. This may be effected e.g. by. mixing the pigment or dye with the resin, heating the vmixture to melting, and kneading the melt. The kneaded mass is then cooled, broken, and ground to fine powder.
• the mannerin which the liquid composition is produced is by no way critical. As is illustrated by the Examplesnhereinafter, it is conventional to prepare by means ofsuitahle mixers, e.g. 3-rollmills, ball mills, colloid mills, homogenizers, high speed stirrers, etcl a concentrate in the insulating carrier liquid of the materials selected for the composition, and subsequently adding further insulating carrier liquid to provide the liquid toner composition ready for use in the electrostatic reproductionprocess.
• suitableahle mixers e.g. 3-rollmills, ball mills, colloid mills, homogenizers, high speed stirrers, etcl a concentrate in the insulating carrier liquid of the materials selected for the composition, and subsequently adding further insulating carrier liquid to provide the liquid toner composition ready for use in the electrostatic reproductionprocess.
• the resin-coated pigment or dye is employed in the composition ready for use in the amount necessary to be capable of being deposited, when attracted to the electrostatic image,-so that the desired image density is reached.
• the pigment or colouring agent is used in an amount comprised between about 0.01 g and 10 g per litre, preferably between about 0.01 g and about 2 g per litre.
• the ratio of resin to pigment'or dye may vary within .very wide limits The resin preferably outweighs the pigment or dye but should permit to obtain sufficient density.
• a preferred weight ratio is comprised between about 1:1 andaboutlzlO. l
• EXAMPLE 1 200 g of STAYBELITE ESTER l (Hercules) and 100 g of Helioecht Blau HG (Bayer) were mixed at 6065C in a mixing and kneading apparatus of MEILI, Switzerland, type liliput O30 L.N. The kneaded mass was cooled and ground in a grinding apparatus l.K.A., model A (of Janke & Kunkel, W. Germany) to obtain a fine powder of resin-coated pigment.
• ANTARON V 216 or of the above zinc salt improve the stability of the developer but at the cost of a reduction of the developable maximum density. For a given density region, however, the optimum stability can be determined.
• Example I was repeated with the only difference that the pigment now used was Fanalrosa B supra pulver (BASF).
• a stable positive-working electrophotographic liquid developer was formed suitable for continuous tone reproduction.
• EXAMPLE 4 EXample l was repeated with the only difference that the pigment now used was carbon black (PRIN- TEX G marketed by Degussa A.G., W.-Germany) and that 0.1 g of the solution of ANTARON V2 l 6 was used and 10 ml of the zinc salt solution.
• carbon black PRIN- TEX G marketed by Degussa A.G., W.-Germany
• Example 1 was repeated with the only difference that in the preparation of the resin-coated pigment, the 200 g of STAYBELITE ESTER l0 (Hercules) was replaced by 200 g of POLYPALE ESTER l0 (Hercules).
• Example I was repeated with the only difference that in the preparation of the resin-coated pigment, the 200 g of STAYBELITE ESTER l0 (Hercules) was replaced by 200 g of PENTALYN A (Hercules).
• Example I was repeated with the only difference that in the preparation of the resin-coated pigment, the 200 g of STAYBELITE ESTER 10 was replaced by 200 g of a coumarone-indene resin marketed by the PICCO Comp, USA, under the trade name PICCOVAR 440 and that in the preparation of the developer concentrate l g of the ANTARON V 216 solution was used.
• An ideal positive-working electrophotographic liquid developer was obtained suitable for the reproduction of continuous tone images.
• Example 1 was repeated with the only difference that in the preparation of the resin-coated pigment, part of the STAYBELITE ESTER 10 was replaced by PICCO' VAR 440.
• EXAMPLE 10 form a positiveworking electrophotographic liquid developer giving high density images when used for the development of electrostatic charge patterns.
• Example 10 was repeated with the difference that in the preparation of the developer concentrate 6 g of the NEOCRYL B 702 solution and 6 g of the ANTARON V 216 solution were used. 1
• a highly stable positive-working electrophotographic liquid developer was obtained suitable for continuous tone reproduction.
• the maximum density obtainable was slightly lower than with the developer of example b 10.
• Example 10 was repeated with the difference that in the preparation of the developer concentrate 1 1.5 g of the NEOCRYL B 702 solution and 0.5 g of the AN- TARON V 216 solution were used and that also 4 ml of a 0.2 7: (g/vol) solution in ISOPAR G of the zinc salt of mono-2-butyloctylphosphate was added.
• the positive-working electrophotographic liquid developer obtained upon dilution had high-stability and yielded upon use for the development of electrostatic charge patterns images of favourable density.
• Example 10 was repeated using MlCROLlTl-l CT (a resincoated carbon black of CIBA, the said resin being STAYBELITE ESTER 10) as pigment.
• a positive-working liquid electrostatic developer suitable for continuous-tone reproduction was obtained.
• Example 10 was repeated using MlCROLlTl-l Gelb 2GT (a resin-coated yellow pigment of CIBA) as pigment.
• a positive-working liquid electrostatic developer suitable for continuous-tone reproduction was obtained.
• EXAMPLE 15 The liquid electrostatic developer compositions of examples 1. 2 and 3 can be used successfully for the reproduction of multicolour images.
• a panchromatically sensitized photoconductive zinc oxide element having a paper support was negatively charged (about 400 V) and exposed through a blue filter (e.g. a Kodak Wratten filter 473 or an Agfa- Gevaert band filter V449) to a multicolour photographic silver halide transparency fitted in a conventional photographic enlarger.
• the selectively discharged photoconductive layer was developed by means of 'the yellow electrostatic liquid developer of example 2' to form the yellow separation image.
• the photoconductive element carrying the yellow toner image was then recharged either in dry or wet condition and again exposed (in register) to the transparency, now through a green filter (e.g. a Kodak Wratten filter 61 or an Agfa-Gevaert band filter U531
• a green filter e.g. a Kodak Wratten filter 61 or an Agfa-Gevaert band filter U531
• the selectively discharged pip toconductive layer was developed by means of the magenta electrostatic liquid developer of example 3 to form the magenta separation image.
• a red filter e.g. a Kodak Wratten filter 29 or an Agfa-Gevaert cut-off filter L622. Development occurred by means of the cyan electrostatic liquid developer of example 1 to form the cyan separation image.
• a positive-working electrostatic liquid developer which will develop electrostatic charge patterns comprising an electrically insulating carrier liquid having a dielectric constant of less than 3 and a volume resistivity in excess of 10 Ohm.cm, resin-coated toner particles suspended in said carrier liquid, and an alkylated polymer of a heterocyclic N-vinyl monomer.
• a liquid developer according to claim 1 wherein said alkylated polymer of a heterocyclic N-vinyl monomer is an alkylated polymer of a N-vinyl lactam monomer.
• N-vinyl lactam monomer is a N-vinyl pyrrolidone or a N-vinylpiperidone.
• a liquid developer according to claim 1 wherein said alkylated polymer is formed by alkylation with an alpha-olefin.
• a liquid developer according to claim 4 wherein said alpha-olefin comprises from 8 to 42 carbon atoms.
• a liquid developer according to claim 1 which also comprises a metal soap of a fatty acid.
• a liquid developer according to claim 1 which also comprises a bivalent or trivalent metal salt of oxyacid derived from phosphorus containing at least one organic residue.
• a liquid developer according to claim wherein said oxyacid derived from phosphorus containing at least one'organic residue is a monoester or diester of an oxyacid derived from phosphorus.
• Method of preparing an electrostatic liquid developer for the development of electrostatic charge patterns by mixing toner particles with an electrically insulating carrier liquid having a dielectric constant of less than 3 and a volume resistivity in excess of 10 ohm.cm, wherein mixing occurs in the presence of an alkylated polymer of a heterocyclic N-vinyl monomer and the said toner particles are coated with a resin prior to mixing was to form a positive-working electrostatic liquid developer.
• alkylatedv polymer of a heterocyclic N-vinyl monomer is an alkylated'poly'mer of a N-vinyl lactam monomer.
• N- vinyl lactammonomer is a N-vinyl pyrrolidone or a N- vinylpiperidone.
• alpha-olefin comprises from 8 to 42 carbon atoms.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Liquid Developers In Electrophotography (AREA)

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• 1972
  • 1972-07-12 GB GB3265572A patent/GB1438954A/en not_active Expired
• 1973
  • 1973-06-28 US US374774A patent/US3909433A/en not_active Expired - Lifetime
  • 1973-07-06 DE DE2334353A patent/DE2334353C2/de not_active Expired
  • 1973-07-09 JP JP48077367A patent/JPS4945744A/ja active Pending
  • 1973-07-09 FR FR7325159A patent/FR2192329B1/fr not_active Expired
  • 1973-07-11 BE BE1005225A patent/BE802171A/xx not_active IP Right Cessation
  • 1973-07-11 CA CA176,226A patent/CA1005671A/en not_active Expired

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