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Publication numberUS3058914 A
Publication typeGrant
Publication dateOct 16, 1962
Filing dateSep 24, 1958
Priority dateOct 1, 1957
Also published asDE1089631B
Publication numberUS 3058914 A, US 3058914A, US-A-3058914, US3058914 A, US3058914A
InventorsMetcalfe Kenneth A, Wright Robert J
Original AssigneeCommw Of Australia
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Non-inflammable liquid developers for electrostatic images
US 3058914 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

3,058,914 Patented Oct. 16, 1962 3,058,914 NON-INFLAMll/IABLE LlQUlD DEVELOPERS FOR ELECTROSTATIC IMAGES Kenneth A. Metcalie, Graymore, South Australia, and

Robert J. Wright, Hectorville, South Australia, Australia, assiguors to The Commonwealth of Australia, Melbourne, Victoria, Australia No Drawing. Filed Sept. 24, 1958, Ser. No. 7 62,912 Claims priority, application Australia, Oct. 1, 1957 2 Claims. ((31. 252-621) This invention relates to non-inflammable liquid developers for electrostatic images.

It is already known to develop electrostatic images by applying either a dry powder to the image or by subjecting the image to liquid development in a carrier having a sufiiciently high electrical resistivity to prevent destruction of the electrostatic image during development.

Liquids having the required characteristics are generally of an inflammatory nature and while the hazard of using them is extremely small or non-existent under suitable operating conditions, an object of this invention is to provide an improvement with respect to this type of developer which will ensure that the danger of fire is completely removed or substantially reduced.

As such liquid developers are generally handled by operators, it is desirable that they be non-toxic and this invention therefore seeks to provide a liquid developer for electrostatic images which is both non-inflammable and non-toxic in ordinary use.

We have found that such a developer can be formed by using as the liquid carrier having the necessary high electrical resistivity, substances of the chlorofluoromethane, or ethane, group.

Amongst the substances which we have found of particular interest are the chlorinated fluorinated hydrocarbon solvents or refrigerants or propellants.

These substances are non-inflammable, non-explosive, are relatively non-toxic, and, provided the correct grouping is chosen, are sufficiently stable in use to permit them to be used commercially as the suspending medium for pigment or developer substance in electrostatic image development.

The substances of the invention should have a dielectric constant less than 3, preferably less than 2.5 and should be sufiiciently stable under various conditions.

One of the advantages of using ffuorinated hydrocarbon solvents or refrigerants or propellants is that a high degree of volatility can be attained, the effect of this being to speed up development and permitting very quick removal of the carrier medium and thereby ensuring the rapid fixing and drying of the developed image.

Two substances which have been found to give very favorable results are trichloromonofluoromethane (CCl F) as sold under the trademark Freon MF and trichlorotrifluoroethane (CCl -CClf sold under the trademark Freon TF. I

The substances are good carriers for the pigment materials, and have the necessary solvent action for the resins or other substances which may be used with liquid developers to act as control and fixing agents.

To enable the invention to be fully understood the following examples are given:

Example 1 15 grams of a phenol modified penta-erythritol ester of rosin such as that known under the trade name Pentarol 20 (acid value 7-15, specific gravity at 20 C. 1.09, melting range 110l20 C.) is digested'in 25 grams of Xylene (a non-polar liquid having a volume resistivity of at least 10 ohm-centimetre and a dielectric constant of less than 3), and when solution is completed, 15 grams of a linseed oil modified alkyd resin of medium oil length such as that known under the trade name Rhodene L6/ (oil length 52%, acid value 610, specific gravity at 20 C. 0955-0965) is added.

grams of phthalocyanine blue is then added to the above coating mix and blended either in a ball mill or a triple roller mill until mixing is complete and pigment :particle size is reduced to the required fineness, such as 0.5 micron, average. I

Eight hours milling in a ball mill is usually sufficient, after which it will 'be found that the pigment particles are coated with a thin film, continuous 'or discontinuous, of the coating mix one component being relatively insoluble in the carrier to act as the control agent and the other sufiifficiently soluble to act as the fixing agent when the carrier liquid is evaporated.

This coating mix will thus influence the surface charge of the coated particles and will form the bonding means after the pigment is applied in a liquid development process.

The paste so produced is used as the basis for a dispersion in the chlorinated fluorin-ated hydrocarbon solvent forming the developer carrier liquid, approximately 0.5 gram of the developer paste being dispersed in 100 mils of the liquid.

To develop an electrostatic image, the liquid developer so formed is simply contacted with the image, and the coated pigment particles, which are free to move in the liquid, deposit on those areas of the image where a suitable potential exists, until the charge of the image has been satisfied by the particles deposited, the particles being held in position by the electrical force until the carrier liquid is evaporated, whereupon the pigment particles are held by direct adhesion of the resin on the surface of the particles.

During development, the presence of the resin infiuences the particle charge, and it is found that rapid deposition is possible of the particles when they are so coated.

The coating mix according to the above example is, as said, only partly soluble in the carrier liquid, and therefore, while the partly dissolved surface of the coating is in a condition where it will form an effective bonding medium after evaporation of the solvent, it will act as a surface charge modifier during development to control the migration of the particles in an electrical field.

In the case of the trichlorotrifluoroethane it is desirable to grind the paste into the carrier liquid as otherwise solubility of the paste in the liquid will be too low and difficulty may be experienced in getting eifective adhesion of the coated pigment particles after evaporation of the carrier.

The developer paste described is more soluble in the trichloromonofluoromethane and simple mixing, without grinding, is found suflicient.

If desired, a mixture of the two carriers referred to may be used, for instance 60% of Freon MP and 40% of Freon TF. Freon MF or Freon TF may be combined with a less volatile, or an inflammable type of carrier provided the compounded carrier has a volume resistivity in excess of 10 ohm-centimetre and a dielectric constant of not greater than 3. A suitable mixture would be Freon MF 80 parts and xylene 20 parts the resulting mixture still being non-inflammable.

The percent-age can, of course, be varied according to conditions.

Example 2 The developer of Example 1 can be modified by re- .the developer then acts as one placing the Rhodehe L6/100 with an equal percentage of Pentarol 20, whereupon it Will be found that the developer will have good fixing qualities but will not have the same degree of modification of the surface charge ofi thepigment particles as the Pentarol 20 is relatively soluble in the hydrocarbon carrier liquid and is a tacky substance, so that it tends to leave the pigment particles when in the developer and deposit :as a. fixing substance.

If sufi'icient tacky substance is substances to cause it to remain there ment, the developer can he said to have both a charge modifying agent and a fixing agent.

present on the pigment r 7 Example 3 V The developer of example 1 has the Pentarol 20 replaced by an equal percentage of Rhodene L6/100,

.prising a chlorinated fluorinated hydrocarbon carrier .liquid selected from the group consisting of trichloroduring developcharge modifier for said substantial volatility to monofluoromethane and :trichlorotrifiuoroethane and mixtures thereof, pigment particles dispersed in said liquid, and resins constituting a coating on said particles, one of said resins being relatively soluble in said liquid and constituting a fixing agent for said particles whereby the particles may be fixed tola surface, another of said resins being relatively insoluble in said liquid and being of such composition as to constitute an electrostatic particles,.said liquid having a insure a rapid fixing of said particles to said surface.

2. A developer as defined in claim 1 further comprising a non-polar liquid having a volume resistivity of at least 10 ohm-centimetre and a dielectric constant of less than 3.

References Cited in the file of this patent UNITED STATES PATENTS 2,379,070 7 Evans etal June 26, 1945 2,381,753 Irion Aug. 7, 1945 2,693,391 Manseau Nov. 2, 1954 2,728,495- Eaton Dec. 27, 1955 2,731,436 Stetz et a1 Jan. 17, 1956 2,742,321 Mina et a1. Apr. 17, 1956 2,377,133 Mayer Mar. 10, 1959 3,010,842 Ricker Nov. 28, 1961 OTHER REFERENCES Metcalfe: Liquid Developers for Xerography, J. of Sci. Instruments, vol. 32, February 1955, pp. 74-75.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2379070 *Mar 14, 1941Jun 26, 1945Du PontPigment dispersions
US2381753 *Jan 3, 1941Aug 7, 1945Gen Printing Ink CorpPrinting ink
US2693391 *Feb 21, 1951Nov 2, 1954David O ManseauSpray bomb
US2728495 *Apr 19, 1951Dec 27, 1955Little Inc ALiquid dispensing device and composition therefor
US2731436 *Feb 25, 1950Jan 17, 1956Engine Parts Mfg CompanyMetallic paint
US2742321 *Jul 27, 1955Apr 17, 1956Chemway CorpPackages of self-propelling atomizing low pressure liquid compositions
US2877133 *Oct 22, 1956Mar 10, 1959Gen Dynamics CorpElectrostatic photography
US3010842 *Aug 29, 1955Nov 28, 1961Xerox CorpDevelopment of electrostatic images
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3212916 *Sep 20, 1961Oct 19, 1965Commw Of AustraliaMethod of developing electrostatic image with foam liquid developer
US3220830 *Oct 2, 1961Nov 30, 1965Kenffel & Esser CompanyMethod of developing a negative electrostatic latent image
US3241998 *Jul 3, 1961Mar 22, 1966Australia Res LabMethod of fixing xerographic images
US3244633 *Oct 24, 1961Apr 5, 1966Gen Aniline & Film CorpLiquid developers for developing electrostatic images
US3296140 *Feb 13, 1964Jan 3, 1967Dick Co AbLiquid developer for electrographic printing
US3384488 *Jul 21, 1967May 21, 1968Xcrox CorpPolychromatic photoelectrophoretic imaging composition
US3384565 *Jul 23, 1964May 21, 1968Xerox CorpProcess of photoelectrophoretic color imaging
US3384566 *Jul 21, 1967May 21, 1968Xerox CorpMethod of photoelectrophoretic imaging
US3391014 *Apr 27, 1964Jul 2, 1968Harris Intertype CorpLiquid development of electrostatic images
US3391015 *Apr 27, 1964Jul 2, 1968Harris Intertype CorpLiquid development of electrostatic images with carbon black and a solid organic pigment
US3438904 *Jan 10, 1966Apr 15, 1969Scm CorpLiquid toner
US3507794 *Nov 7, 1966Apr 21, 1970Harris Intertype CorpElectrostatic photography systems
US3535244 *Apr 27, 1966Oct 20, 1970Dick Co AbLiquid developer composition for electrostatic images
US3640751 *Oct 31, 1968Feb 8, 1972Ricoh KkMethod for liquid-developing an electrostatic image
US3640863 *May 28, 1969Feb 8, 1972Ricoh KkA liquid electrostatic having pigment particles coated with a cyclized rubber
US3714048 *Sep 28, 1970Jan 30, 1973Iwatsu Electric Co LtdElectrophotographic liquid developer containing asphalt and modified alkyl resin
US3770485 *Sep 20, 1971Nov 6, 1973Ricoh KkMethod for liquid-developing an electrostatic image
US4285801 *Sep 20, 1979Aug 25, 1981Xerox CorporationElectrophoretic display composition
US5643707 *Jul 31, 1995Jul 1, 1997Xerox CorporationLiquid developer compositions
US5952048 *Jul 22, 1997Sep 14, 1999Ricoh Company, Ltd.Ink composition and recording method using the same
US6479205 *Jan 20, 1995Nov 12, 2002Indigo N.V.Imaging apparatus and toner therefor
US7354691Nov 12, 2002Apr 8, 2008Hewlett-Packard Development Company, L.P.Imaging apparatus and improved toner therefor
US7647008Jan 12, 2010Hewlett-Packard Indigo B.V.Imaging apparatus and improved toner therefor
US7678525Mar 16, 2010Hewlett-Packard Development Company, L.P.Imaging apparatus and improved toner therefor
US20030059701 *Nov 12, 2002Mar 27, 2003Benzion LandaImaging apparatus and improved toner therefor
US20030068570 *Nov 12, 2002Apr 10, 2003Benzion LandaImaging apparatus and improved toner therefor
US20080056779 *Oct 31, 2007Mar 6, 2008Benzion LandaImaging Apparatus and Improved Toner Therefor
Classifications
U.S. Classification430/116, 430/115
International ClassificationG03G9/12, G03G9/125
Cooperative ClassificationG03G9/125
European ClassificationG03G9/125