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
  • G03G9/135—Developers with toner particles in liquid developer mixtures characterised by stabiliser or charge-controlling agents
• • 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

Definitions

• a liquid developer for developing an electrostatic latent image comprising a carrier liquid having more than 10 0 cm. of specific resistance, toner particles which are insoluble in said carrier liquid, l-hydroxyalkyl-Z-higher aIkyI-Z-imidazoline which is soluble in the carrier liquid and a copolymer of half-alkylamide of maleic acid and diisobutylene which is soluble in the carrier liquid is disclosed.
• the present invention relates to a developer used for developing electrostatic latent images and more particularly to an improved liquid developer for converting electrostatic latent images into visible images in the electrophotographic or electrostatic printing processes.
• This improved developer is especially useful when developing electrostatic latent images on an insulating surface by the use of toner particles which are charged positively.
• An optical image of an original image is projected to the charged surface of the sensitive layer, whereby the uniformly charged surface is discharged imagewise corresponding to the light intensity and an electrostatic latent image is formed.
• electroscopic toner particles By applying electroscopic toner particles to this electrostatic latent image, a visible image is produced. In the Electrofax process, this visible image is fixed directly to the photoconductive surface. It is necessary when copying ordinary documents to obtain a positive reproduction from an optically positive original. Accordingly, when the surface of the sensitive layer is charged negatively, the electroscopic toner particles should have a strong and stabilized positive charge.
• Today many kinds of liquid developers including toner particles of positive polarity have been marketed.
• the liquid developer of the present invention is characterized in that it can produce a high image density. Further, the developed image is substantially free of streaks and background toner deposition (fog). Furthermore, the toner particles contained in the liquid developer of the present invention are stable over extended periods 3,772,199 Patented Nov. 13, 1973 of time as concerns the dispersion and the electrophoretic properties.
• the liquid developer of the present invention is characterized by containing l-hydroxyalkyl-Z-higher alkyl-2- imidazoline and a copolymer of half-alkylamide of maleic acid and diisobutylene dissolved in a carrier lipuid.
• Suitable toners include carbon black, Aniline black, Crystal Violet, Phthalocyanine Black, Phthalocyanine Green, Molori Blue, Hausa Yellow, Quinacrydone Red, Quinacrydone Violet, Phthalocyaniue Blue, Quinacrydone Magenta and Benzidine Yellow.
• These pigments are prepared as a concentrated pigment paste, namely a concentrate of toner particles.
• An improved liquid developer can be produced by diluting the concentrated pigment paste with the carrier liquid.
• the pigment paste of toner particles is admixed with Imidazoline A, Copolymer B, and if desired, resins which are soluble in the carrier liquid.
• a carrier liquid is admixed with this admixture, i.e. the pigment paste, it is capable of easily providing a developer having a desired concentration which is suitable for the specific use by adding a suitable amount of the carrier liquid at use.
• the particle size of the toner suitable as the developer of the present invention be less than 5 microns and preferably less than 1 micron so as to obtain a high quality continuous tone image.
• the hydroxyalkyl group in the lhydroxyalkyl 2 higher alkyl 2 imidazoline (Imidazoline A) used in the present invention contain 1 to 7 carbon atoms and preferably be hydroxyethyl, hydroxypropyl or hydroxybutyl. Further, it has been found that those higher alkyl groups having 6-22 carbon atoms as the higher alkyl group are preferable for the purpose of the present invention in the viewpoint of charge controlling ability and solubility in the carrier liquid.
• a copolymer of half-alkylamide of maleic acid and diisobutylene is used together with the above-mentioned imidazoline A. It has also been found that the half-alkylamide having an alkyl group of 24 carbon atoms and having a molecular weight of 1000- 50,000 is preferable for the purpose of the present invention, since it has good solubility in the carrier liquid ordinarily used and excellent charge controlling ability.
• the molar ratio of monomer in the copolymer may be varied in a wide range, but copolymers having a ratio of half-alkylamide of maleic acid and diisobutylene of about 1:1 to about 1:5 are preferably used.
• the carrier liquid used in the improved developer of this invention may be a hydrocarbon solvent, for example, cyclohexane, Decalin, kerosene, isoparaffin, light oil and gasoline, etc.
• Other carrier liquids suitable for use include chlorofluorinated hydrocarbon solvents and silicone oils which can be used solely or as a mixture.
• the liquid should have a specific resistance of more than 10 0 cm. and preferably more than 10 82 cm.
• resins which are soluble in the carrier liquid may be used as dispersion promoting agents.
• the resins which serve this purpose include alkyd resins which are well-known in the field of this technology, styrene polymers, rosin, asphalt, and polybutene; many vegetable oils can be used also.
• a small amount of additives such as saturated fatty acids, unsaturated fatty acids, salts thereof and anti-oxidants, etc., may be added as is typical in the art.
• a toner may be blended with a resin, Imidazoline A and Copolymer B. The mixture is then diluted by a carrier liquid in a suitable amount to produce a developer having a predetermined toner concentration.
• a toner is kneaded initially with a resin and then the mixture is diluted with a carrier liquid containing Imidazoline A and Copolymer B.
• time of addition of Imidazoline A and Copolymer B to the liquid developer can be selected freely.
• a preferable toner concentration is 0.1-50 parts by weight based on 1000 parts of the liquid carrier.
• the toner concentration is too low, image density tends to be insufiicient in a short development period and when the toner concentration is too high, background toner deposition becomes great.
• Copolymer B Since the Copolymer B has a high charge controlling ability, good effect is brought about with the addition of 0.0005 part of this compound based on 1000 parts of the carrier liquid. An excellent result is brought about by the addition of 0.00l-0.05 part of Copolymer B based on 1000 parts of the carrier liquid. Addition of the Copolymer B in the amount beyond this range causes lowering of the image density.
• Imidazoline A is preferably used in the amount of Ma- 20 times (by weight) of the amount of Copolymer B. But the allowable maximum amount of Imidazoline A is 0.5 part based on 1000 parts of the carrier liquid. Addition of the Imidazoline A in an amount beyond this range is apt to bring about lowering of the image density.
• the resins which are soluble in the carrier liquid may be added in the amount of one to 50 times the amount of the toner. However, it is preferable that the amount does not exceed 100 parts based on 1000 parts of the carrier liquid. Addition of the resins is not necessary when using a grafted toner which comprises a pigment and polymer chains chemically bonded onto the pigment surface, such as described in Belgian Pat. No. 706,742 and US. Pat. No. 3,503,881.
• This type of developing agent comprises a reaction product produced by a graftpolymerization to a pigment such as carbon black of an alkyl ester of acrylic or methacrylic acid, and on occasion, further of a small amount of polar monomer such as acrylic acid, acrylic amide, etc.
• the developing agent of this type is added to a carrier liquid together with the imidazoline and the copolymer of the present invention to form a liquid developer having the above-mentioned superior properties. In this case it is not necessary to add the resin soluble in the carrier liquid to the carrier liquid.
• the upper limit of the sum of various additives added to the liquid developer of the present invention depends mainly to what extent the electrical resistivity of the resulting developer is lowered.
• the liquid developer should show an electrical resistance not less than 5 10 n cm. when measured after the removal of the dispersed particles. Thus, it is necessary to control the amount of each additive.
• an electrophoretic process is preferably utilized. By removing the toner by the electrophoretic process, the pigment dispersed and additives strongly adsorbed on or associated with the pigment surface are removed.
• the remaining liquid phase which consists of a carrier liquid
• a concentrated pigment paste of the following formulation was prepared which could be diluted with a carrier liquid to form a liquid developer.
• Isoper-H Isoparafiinc solvent produced by. Esso Standard Oil Co.
• an electrophotographic zinc oxide sensitive layer was charged uniformly by a corona electrode applied to 7 kv. in the dark. Then, the layer was exposed to light through a positive original having a continuous gradation to form an electrostatic latent image thereon.
• the sheet After being wetted at the surface bearing the electrostatic latent image with Isoper-H not containing any toner, the sheet was immersed in the liquid developer described above for 30 seconds, using a development electrode. The surface of the sensitive layer after development was washed with fresh Isoper-E (Isoparaffin type solvent produced by Esso Standard Oil Co.). Thus, a positive reproduction of the continuous tone image could be obtained.
• the maximum optical reflection density of the image was 2.24 and the minimum (fog density) was 0.07. Streaks of tone were hardly observed in the image.
• a positive image having a maximum optical density of 2.20 and a minimum 0.07 was obtained. No substantial change was observed as for the dispersion condition of the toner. The image exhibited a somewhat warm black appearance.
• COMPARATIVE EXAMPLE 1 A liquid developer was produced by the same procedure as in Example 1, but excluding 1-hydroxyethyl-2-decyl-2- imidazoline. Development was carried out by the same procedure as in Example 1. A positive image having an optical density of a maximum of 2.20 and a minimum of 0.09 was obtained. Slight tendency of streaking was observed in the image. When developed at the same conditions after being preserved for 50 days at room temperature, a positive image having a maximum optical density of 1.78 and a minimum of 0.10 was obtained. Precipitation of a small amount of the toner was observed on the bottom of the container.
• COMPARATIVE EXAMPLE 2 A liquid developer was prepared by the same procedure as in Example 1, but only excluding the copolymer of half docosanylamide of diisobutylene. Then development EXAMPLE 2 The copolymer of half-dooosanylamide of maleic acid and diisobutylene was replaced by half-octadecylamide in the preparation of a developer as described in Example 1. When developed by the same procedure as in Example 1, an image having a maximum optical density of 2.12 and a background, or minimum density of 0.08 was obtained.
• EXAMPLE 3 A liquid developer was prepared using a mixture of 0.15 part of 1-hydroxyethyl-2-dodecyI-Z-imidazoline and 0.005 part of 1-hydroxyethyl-2-stearyI-Z-imidazoline instead of 0.2 part of 1-hydroxyethyl-2-dodecyl-2-imidazoline used in Example 1. With the development according to the same procedure as described in Example 1, a substantially equivalent result was obtained.
• EXAMPLE 4 9 parts of carbon black and 1 part of Phthalocyanine Blue were used as a pigment mixture instead of parts of carbon black used in Example 1. By practicing the same procedure as in Example 1, an image having a slightly blue-black appearance resulted.
• a liquid developer for developing an electrostatic latent image comprising a carrier liquid having more than 10 0 cm. of specific resistance, toner particles of diameter less than 5 microns which are insoluble in said carrier liquid, l-hydroxyalkyl-Z-higher alkyl-Z-imidazoline which is soluble in said carrier liquid, said hydroxyalkyl containing from 1 to 7 carbon atoms and said higher alkyl containing from 6 to 22 carbon atoms, and a copolymer of half-alkylamide of maleic acid and diisobutylene which is soluble in said carrier liquid, wherein said toner is present in an amount from about 0.1 to 50 parts by weight per 1000 parts of said carrier liquid, said copolymer is present in an amount from about 0.0005 to 0.05 part by weight per 1000 parts of said carrier liquid and the weight ratio of the imidazoline compound to said copolymer is in the range of about A; to 20.
• a liquid developer as claimed in claim 1 wherein the hydroxyalkyl group of said imidazoline is selected from the group consisting of hydroxyethyl, hydroxypropyl and hydroxybutyl.
• a liquid developer for developing an electrostatic latent image comprising a carrier liquid having more than 10 0 cm. of specific resistance, a pigment, a resin which is soluble in the carrier liquid, 1-hydroxy-alkyl-2-higher alkyl-2-imidazoline which is soluble in said carrier liquid, said hydroxyalkyl containing from 1 to 7 carbon atoms and said higher alkyl containing from 6 to 22 carbon atoms, and a copolymer of half-alkylamide of maleic acid and diisobutylene which is soluble in said carrier liquid, wherein said copolymer is present in an amount from about 0.0005 to 0.0 5 part by weight per 1000 parts of said carrier liquid and the weight ratio of the imidazoline compound to said copolymer is in the range of about A; to 20.
• a liquid developer for developing an electrostatic latent image comprising a carrier liquid having more than 10 0 cm. of specific resistance, a graft carbon type developing agent, l-hydroxyalkyl-Z-higher alkyl-2-imidazoline which is soluble in said carrier liquid, said hydroxyalkyl containing from 1 to 7 carbon atoms and said higher alkyl containing from 6 to 22 carbon atoms, and a copolymer of half-alkylamide of maleic acid and diisobutylene which is soluble in said carrier liquid, wherein said copolymer is present in an amount from about 0.0005 to 0.05 part by weight per 1000 parts of said carrier liquid and the weight ratio of the imidazoline compound to said copolymer is in the range of about to 20.
• a liquid developer as claimed in claim 5 wherein said graft carbon type developing agent is the reaction product obtained by graft polymerization of 5 parts of carbon black and 7 parts of lauryl methacrylate.

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

Applications Claiming Priority (1)

Publications (1)

Family

ID=14261855

Family Applications (1)

Country Status (4)

Cited By (14)

Families Citing this family (4)

• 1970
  • 1970-11-13 JP JP45099982A patent/JPS4926596B1/ja active Pending
• 1971
  • 1971-11-11 US US00197961A patent/US3772199A/en not_active Expired - Lifetime
  • 1971-11-11 GB GB5250271A patent/GB1316040A/en not_active Expired
  • 1971-11-11 DE DE2156147A patent/DE2156147C3/de not_active Expired

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