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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/06—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from hydroxycarboxylic acids
  • C08G63/08—Lactones or lactides
• • 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
  • G03G9/135—Developers with toner particles in liquid developer mixtures characterised by stabiliser or charge-controlling agents

Definitions

• This invention relates to an electrostatic liquid developer having improved properties. More particularly this invention relates to an electrostatic liquid developer containing a degradable polymeric resin.
• a latent electrostatic image can be developed with toner particles dispersed in an insulating nonpolar liquid.
• Such dispersed materials are known as liquid toners or liquid developers.
• a latent electrostatic image may be produced by providing a photoconductive layer with a uniform electrostatic charge and subsequently discharging the electrostatic charge by exposing it to a modulated beam of radiant energy.
• Other methods are known for forming latent electrostatic images. For example, one method is providing a carrier with a dielectric surface and transferring a preformed electrostatic charge to the surface.
• Useful liquid developers comprise a thermoplastic resin in particle form and dispersant nonpolar liquid. Generally a suitable colorant is present such as a dye or pigment.
• the colored toner particles are dispersed in the nonpolar liquid which generally has a high-volume resistivity in excess of 10 ⁇ ohm centimeters, a low dielectric constant below 3.0 and a high vapor pressure.
• the toner particles are less than 10 ⁇ m average particle size as measured by a Malvern 3600E laser diffraction light scattering particle analyzer. After the latent electrostatic image has been formed, the image is developed by the colored toner particles dispersed in said dispersant nonpolar liquid and the image may subsequently be transferred to a carrier sheet.
• a charge director compound and preferably an adjuvant e.g., polyhydroxy compound, aminoalcohol, polybutylene succinimide, an aromatic hydrocarbon, etc.
• an adjuvant e.g., polyhydroxy compound, aminoalcohol, polybutylene succinimide, an aromatic hydrocarbon, etc.
• an electrostatic liquid developer having improved degradability compatible with recycling of printed paper, consisting essentially of
• R 1 or R 2 which can be the same or different, is hydrogen, hydrocarbyl containing 1 to 12 carbon atoms, or substituted hydrocarbyl containing 1 to 12 carbon atoms, and a nonpolar liquid having a ' Kauri-butanol value of less than 30, by means of moving particulate media whereby the moving particulate media creates shear and/or impact, while maintaining the temperature in the vessel at a temperature sufficient to plasticize and liquify the resin and below that at which the nonpolar liquid boils and the resin decomposes, B.
• composition of the electrostatic liquid developer does not exclude unspecified components which do not prevent the advantages of the developer from being realized.
• additional components such as fine particle size oxides, adjuvant, e.g., polyhydroxy compound, aminoalcohol, polybutylene succinimide, metallic soap, aromatic hydrocarbon, etc.
• Degradable means that the polymeric acid resin component of the developer is biodegradable, for example in landfills, but more importantly is hydrolyzable by exposure to aqueous conditions, preferably slightly basic or acidic, whereupon the polymeric resin is hydrolyzed to monomeric or low molecular weight units that are suitable for recycle reuse to prepare polymer.
• Aminoalcohol means that there is both an amino functionality and hydroxyl functionality in one compound.
• the dispersant nonpolar liquids (A) are, preferably, branched-chain aliphatic hydrocarbons and more particularly, Isopar®-G, Isopar®-H, Isopar®-K, Isopar®-L, Isopar®-M and Isopar®-V. These hydrocarbon liquids are narrow cuts of isoparaffinic hydrocarbon fractions with extremely high levels of purity.
• the boiling range of Isopar ® -G is between 157°C and 176°C, Isopar®-H between 176°C and 191°C, Isopar®-K between 177°C and 197°C, Isopar®-L between 188°C and 206°C and Isopar®-M between 207°C and 254°C and
• Isopar®-V between 254.4°C and 329.4°C.
• Isopar ® -L has a mid-boiling point of approximately 194°C.
• Isopar ® -M has a flash point of 80°C and an auto-ignition temperature of 338°C.
• Stringent manufacturing specifications such as sulphur, acids, carboxyl, and chlorides are limited to a few parts per million. They are substantially odorless, possessing only a very mild paraffinic odor. They have excellent odor stability and are all manufactured by the Exxon Corporation. High-purity normal paraffinic liquids, Norpar®12, Norpar®13 and Norpar®15, Exxon Corporation, may be used. These hydrocarbon liquids have the following flash points and auto-ignition temperatures: Flash Point Auto-Ignition iaili-d f°C. Temp (° )
• Nonpolar liquids have an electrical volume resistivity in excess of 10 ⁇ ohm centimeters and a dielectric constant below 3.0. The vapor pressures at 25°C are less than 10 Torr.
• Isopar®-G has a flash point, determined by the tag closed cup method, of 40°C
• Isopar®-H has a flash point of 53°C determined by ASTM D 56.
• Isopar®-L and Isopar®-M have flash points of 61°C, and 80°C, respectively, determined by the same method. While these are the preferred nonpolar liquids, the essential characteristics of all suitable nonpolar liquids are the electrical volume resistivity and the dielectric constant.
• a feature of the nonpolar liquids is a low Kauri-butanol value less than 30, preferably in the vicinity of 27 or 28, determined by ASTM D 1133.
• the ratio of resin to dispersant nonpolar liquid is such that the combination of ingredients becomes fluid at the working temperature.
• the nonpolar liquid is present in an amount of 50 to 99.9% by weight, preferably 97 to 99.5% by weight, based on the total weight of liquid developer.
• the total weight of solids in the liquid developer is 0.1 to 50%, preferably 0.3 to 3.0% by weight.
• the total weight of solids in the liquid developer is solely based on the resin, including components dispersed therein, e.g., pigment component, adjuvant, etc.
• the degradable polymeric resin contains at least one hydroxy acid unit selected from the group consisting of
• R 1 R 2 CR 1 R 2 OCR 1 R 2 CR 1 R 2 CO (OCR 1 R 2 CR 1 R 2 OCR 1 R 2 CR 1 R 2 CO) s wherein n is a whole number 2, 4 or 5, the total of p, q, r and s being 15 to 5,000, and R 1 or R 2 , which can be the same or different, is hydrogen, hydrocarbyl containing 1 to 12 carbon atoms, or substituted hydrocarbyl containing 1 to 12 carbon atoms.
• Preferred units are those in which R 1 and R 2 each are hydrogen or methyl, and especially preferred units are epsilon-caprolactone, gamma-valerolactone, lactide(3, 6-dimethyl-l,4-dioxan-2,5-dione) , glycolid- (1,4-dioxan-2,5-dione) , 1,5-dioxepan-2-one, 1,4-dioxan- 2-one, beta-butyrolactone, and beta-propiolactone. Mixtures of these units can be used.
• the polymeric resin can be homopolymer of any of units (1) to (4) , block or random copolymer of at least 2 units of (1) to (4) , blends of homopolymers of any of units (1) to (4) , block or random copolymers of at least two units of (1) to (4), and combinations thereof.
• the degradable resins have the following preferred characteristics:
• CAPA-500 centrifugal automatic particle analyzer solvent viscosity of 1.24 cps, solvent density of 0.76 g/cc, sample density of 7.32 using a centrifugal rotation of 1,000 rpm, a particle size range of 0.01 to less than 10 ⁇ m, and a particle size cut of 1.0 ⁇ m, and, about 30 ⁇ m average particle size, e.g., determined by Malvern 3600E
• Particle Sizer as described below, 5. Are able to fuse at temperatures in excess of 70°C.
• the Malvern 3600E Particle Sizer manufactured by Malvern, Southborough, MA which uses laser diffraction light scattering of stirred samples to determine average particle sizes. Since the Horiba and Malvern instruments use different techniques to measure average particle size the readings differ. The following correlation of the average size of toner particles in micrometers ( ⁇ m) for the two instruments is:
• Suitable nonpolar liquid soluble ionic or zwitterionic charge director compounds (C) which are generally used in an amount of 0.25 to 1,500 mg/g, preferably 2.5 to 400 mg/g developer solids, include: anionic glyceride such as Emphos® D70-30C, Emphos®F 27- 85, two commercial products sold by Witco Corp., New York, NY; which are sodium salts of phosphated mono- and diglycerides with unsaturated and saturated acid substituents, respectively; lecithin, Basic Barium Petronate®, Neutral Barium Petronate®, Calcium Petronate ® , Neutral Calcium Petronate ® , oil-soluble petroleum sulfonates, Witco Corp., New York, NY; and metallic soaps such as aluminum tristearate, aluminum distearate; barium, calcium, lead and zinc stearates; cobalt, manganese, lead and zinc linoleates, aluminum, calcium and cobalt octoates; calcium and cobalt
• colorants such as pigments or dyes and combinations thereof, which are preferably present to render the latent image visible, though this need not be done in some applications.
• the colorant e.g., a pigment
• the amount of colorant may vary depending on the use of the developer.
• pigments include:
• ingredients may be added to the electrostatic liquid developer, such as fine particle size oxides, e.g., silica, alumina, titania, etc.; preferably in the order of 0.5 ⁇ m or less can be dispersed into the liquefied resin. These oxides can be used instead of the colorant or in combination with the colorant. Metal particles may also be added.
• Another additional component of the electrostatic liquid developer is an adjuvant selected from the group consisting of polyhydroxy compound which contains at least 2 hydroxy groups, aminoalcohol, polybutylene succinimide, metallic soap, and aromatic hydrocarbon having a Kauri-butanol value of greater than 30.
• the adjuvants are generally used in an amount of 1 to 1000 mg/g, preferably 1 to 200 mg/g developer solids.
• the various above-described adjuvants include: Oolyhvriroxy compounds; ethylene glycol, 2,4,7,9- tetramethyl-5-decyn-4,7-diol, poly(propylene glycol), pentaethylene glycol, tripropylene glycol, triethylene glycol, glycerol, pentaerythritol, glycerol-tri-12 hydroxystearate, ethylene glycol mcnohydroxystearate, propylene glycerol monohydroxy-stearate, etc. as described in Mitchell U.S. Patent 4,734,352.
• aminoalcohol compounds triisopropanolamine, triethanolamine, ethanolamine, 3-amino-l- propanol, o-aminophenol, 5-amino-l-pentanol, tetra (2-hydroxy- ethyl) ethylenediamine, etc. as described in Larson U.S. Patent 4,702,985.
• polybutylene succinimide OLOA®-1200 sold by Chevron Corp., analysis information appears in Kosel U.S.
• Amoco 575 having a number average molecular weight of about 600 (vapor pressure osmometry) made by reacting aleic anhydride with polybutene to give an alkenylsuccinic anhydride which in turn is reacted with a polyamine.
• Amoco 575 is 40 to 45% surfactant, 36% aromatic hydrocarbon, and the remainder oil, etc.
• metallic soap aluminum tristearate; aluminum distearate; barium, calcium, lead and zinc stearates; cobalt, manganese, lead and zinc linoleates; aluminum, calcium and cobalt octoates; calcium and cobalt oleates; zinc palmitate; calcium cobalt, manganese, lead and zinc naphthenates; calcium, cobalt, manganese, lead and zinc resinates; etc.
• the metallic soap is dispersed in the thermoplastic resin as described in Trout U.S. Patents 4,707,429 and 4,740,444.
• aromatic hydrocarbon benzene, toluene, naphthalene, substituted benzene and naphthalene compounds, e.g., trimethylbenzene, xylene, dimethylethylbenzene, ethylmethylbenzene, propylbenzene, Aromatic 100 which is a mixture of Cg and C ⁇ Q alkyl- substituted benzenes manufactured by Exxon Corp., etc. as described in Mitchell U.S. Patent 4,631,244.
• organic sulfur-containin ⁇ compounds sulfonic acid, organic sulfonates, organic sulfate, sulfinic acid and salts thereof as described in column 5, line 7, to column 6, line 20 of El-Sayed and Trout U.S. Patent 4,917,985.
• the particles in the electrostatic liquid developer have an average by area particle size of less than 10 ⁇ m as measured by the Horiba CAPA-500 centrifugal automatic particle analyzer described above, preferably the average by area particle size is less than 5 ⁇ m.
• the resin particles of the developer may or may not be formed having a plurality of fibers integrally extending therefrom.
• fibers as used herein means pigmented toner particles formed with fibers, tendrils, tentacles, threadlets, fibrils, ligaments, hairs, bristles, or the like.
• the electrostatic liquid developer can be prepared by a variety of processes.
• a suitable mixing or blending vessel e.g., attritor, heated ball mill, heated vibratory mill such as a Sweco Mill (manufactured by Sweco Co., Los Angeles, CA) , equipped with particle media for dispersing and grinding, or mixing and blending equipment which requires no particulate media such as a Ross double planetary mixer (manufactured by Charles Ross and Son, of Hauppauge, NY) , Banbury mixer, single-screw extruder, double-screw extruder, heated two roll mill, etc., are placed the resin, and, if desired, dispersant nonpolar liquid described above. Generally the resin, nonpolar liquid and optional colorant are placed in the vessel prior to starting the dispersing step. Optionally the colorant can be added after homogenizing the resin and the 14
• Nonpolar liquid can also be present in the vessel, e.g., up to 100% by weight based on the weight polar additive and nonpolar liquid (total liquid) .
• the dispersing step is generally accomplished at elevated temperature, i.e., the temperature of ingredients in the vessel being sufficient to plasticize and liquefy the resin but being below that at which the nonpolar liquid or polar additive, if present, degrades and the resin and/or colorant decomposes.
• a preferred temperature range is 80° to 185°C. Other temperatures outside this range may be suitable, however, depending on the particular ingredients used.
• the presence of the irregularly moving particulate media in the vessel is preferred to prepare the dispersion of toner particles .
• Useful particulate media are particulate materials, e.g., spherical, cylindrical, etc. selected from the group consisting of stainless steel, carbon steel, alumina, ceramic, zirconia, silica, and sillimanite. Carbon steel particulate media is particularly useful when colorants other than black are used.
• a typical diameter range for the particulate media is in the range of 0.04 to 0.5 inch (1.0 to - 13 mm) .
• the dispersion is cooled, e.g., in the range of 0°C to 50°C. Cooling may be accomplished, for example in the same vessel, such as the attritor. Additional liquid may be added at any step during the preparation of the liquid electrostatic developer to facilitate grinding or to dilute the developer to the appropriate % solids needed for toning. Additional liquid means nonpolar liquid, polar liquid, or combinations thereof. Cooling is accomplished by means known to those skilled in the art and is not limited to cooling by circulating cold water or a cooling material through an external cooling jacket adjacent the dispersing apparatus or permitting the dispersion to cool to ambient temperature. The resin precipitates out of the dispersant or solidifies during the cooling.
• a desirable cooling step (B) technique is to cool the dispersion, either.
• Toner particles of average particle size (by area) of less than 10 ⁇ m, as determined by an Horiba CAPA-5000 centrifugal particle analyzer described above or other comparable apparatus, are formed by grinding for a relatively short period of time.
• the concentration of the toner particles in the dispersion is reduced by the addition of additional nonpolar liquid as described previously above.
• the dilution is normally conducted to reduce the concentration of toner particles to between 0.1 to 50 percent by weight, preferably 0.3 to 3.0, and more preferably 0.5 to 2 weight percent with respect to the nonpolar liquid.
• One or more nonpolar liquid soluble ionic or zwitterionic charge director compounds (C) can be added to impart an electrostatic charge.
• the addition may occur at any time during the process; preferably at the end of the process, e.g., after the particulate media, if used, are removed and the concentration of toner particles is accomplished.
• the ionic or zwitterionic compound can be added prior to, concurrently with, or subsequent thereto.
• an adjuvant compound of a type described above has not been previously added in the preparation of the developer, it can be added prior to or subsequent to the developer being charged. Preferably the adjuvant compound is added after the dispersing step.
• the electrostatic liquid developers of this invention demonstrate good image quality.
• the developers of this invention are useful in copying, e.g., making office copies of black and white as well as various colors; or color proofing, e.g., a. reproduction of an image using the standard colors: yellow, cyan, magenta together with black as desired.
• color proofing e.g., a. reproduction of an image using the standard colors: yellow, cyan, magenta together with black as desired.
• the toner particles are applied to a latent electrostatic image.
• Other uses are envisioned for the electrostatic liquid developers include: digital color proofing, highlight color, lithographic printing plates, and resists.
• the resin particles contained in the developers of this invention are biodegradable (see, for example, H. V. Maulding, et al., Journal of Controlled Release, Vol. 3, Nos. 2-3, p. 103-117 (1986)) and more importantly degradable by hydrolysis, which removes the ink and breaks down the resin to units that can be isolated easily and reconverted to polymeric resin.
• Paper printed with these developers can be processed by standard paper recycle treatment without leaving a gray or spotted discoloration to the recycled paper made therefrom.
• a black developer was prepared by adding 6.63 g of polylactic acid, 1.66 grams Monarch 1000 black pigment, Cabot Corp., Billerica, MA, and 33.2 grams of Isopar®-L to a Union Process 01 Attritor, Union Process Company, Akron, OH charged with 0.1875 inch (4.76 mm) diameter carbon steel balls.
• the polylactic acid was prepared from a 90/10 ratio of L/D,L lactide via melt polymerization using SnCl 2 catalyst, weight average molecular weight 237,000, polydispersity 2.8 (Size Exclusion Chromatography vs. polystyrene standard), melting point 150°C, glass transition temperature of about 50°C.
• the mixture was milled at 165°C for 1 hour then cooled to ambient temperature and the mixture was milled for 26 hours.
• the average particle size was 5.1 ⁇ m measured with a Malvern 3600E Particle Sizer.
• the developer was diluted to 0.5% solids with Isopar®-L and charged up to 100 mg/g developer solids with 10% Basic Barium Petronate®, Witco Corp., New York, NY, in Isopar®-L.
• the mobility of the toner was 8.5xl0 ⁇ 10 m 2 /V- Sec, as measured on a Matec ESA device (Matec Corp., Hopkinton, MA) .
• EXAMPLE 2 Two samples of developed Xerox 4024 copier paper were prepared using the developer prepared as described in Example 1 and a control liquid developer made from a non-degradable resin.
• the control developer is composed of 20% Monarch 1000 black pigment and 80% ethylene (90%)/methacrylic acid (10%) copolymer, melt index at 190°C is 500, acid no. is 54 and prepared by the procedure described in Example 5 of Blair et al., U.S. Patent 4,923,778.
• the developer of Example 1 contains 20% Monarch 1000 black pigment, Cabot Corp., Billerica, MA, and 80% degradable resin. Multiple sheet samples were prepared by applying as a thin film by a drawdown technique each developer to paper base stock. Coverage of the base stock by the toner film was typically about 40-50% for each sheet. The samples, including uninked base stock, were evaluated for ease of de-inking as follows:
• This example demonstrates the superior de-inking properties of the toner prepared with degradable resin when image content consists of large solid areas.
• a control black developer was prepared by adding the following ingredients to a Union Process IS attritor:
• the ingredients were heated to 95°C, milled for one hour, then cooled to ambient temperature. 800 grams of Isopar ® L were then added to the attritor, and the mixture was milled an additional 6 hours. The average particle size was 6.5 ⁇ m measured with a Malvern 3600E Particle Sizer. The toner was diluted to 1.5% solids with Isopar®L, and charged with Basic Barium Petronate ® , Witco Corp. to a final conductivity of 15 pmho/cm.
• composition of the developer of the invention was identical to that of the control, except that the polylactic acid polymer described in Example 1 was substituted for the ethylene/methacrylic acid copolymer.
• the mixture was milled in a Union Process 01 attritor at 175°C for one hour and was cooled to ambient temperature and ground for an additional 16 hours.
• the average particle size was 6.5 ⁇ m measured with a Malvern 3600E Particle Sizer.
• the toner was diluted to 1.5% solids with Isopar ® L, and charged with Basic Barium Petronate® to a final conductivity of 15 pmho/cm.
• Samples were multiple sheets of Xerox 4024 paper base stock to which either the control or liquid developer of the invention had been applied using a Fuji-Xerox 1005 copier modified to print liquid developer.
• the imaged copy was multiline text typical of a normal business letter.
• Optical density of the control and copies of the invention was measured to be 1.15 ⁇ 0.05.
• the samples were evaluated for de-inking as follows:
• This example demonstrates the superior de-inking properties of the toner prepared with degradable resin when image content consists of standard text.

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• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
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• Liquid Developers In Electrophotography (AREA)

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• 1991
  • 1991-06-18 EP EP91913894A patent/EP0543841A1/de not_active Withdrawn
  • 1991-06-18 WO PCT/US1991/004133 patent/WO1992001246A1/en not_active Application Discontinuation
  • 1991-06-18 JP JP91512887A patent/JPH05508940A/ja active Pending
  • 1991-06-18 AU AU82906/91A patent/AU8290691A/en not_active Abandoned
  • 1991-07-12 IL IL98809A patent/IL98809A0/xx unknown

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