Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/02—Charge-receiving layers
  • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
  • G03G5/05—Organic bonding materials; Methods for coating a substrate with a photoconductive layer; Inert supplements for use in photoconductive layers
  • G03G5/0528—Macromolecular bonding materials
  • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
  • G03G5/0567—Other polycondensates comprising oxygen atoms in the main chain; Phenol resins
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/02—Charge-receiving layers
  • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
  • G03G5/05—Organic bonding materials; Methods for coating a substrate with a photoconductive layer; Inert supplements for use in photoconductive layers
  • G03G5/0528—Macromolecular bonding materials
  • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
  • G03G5/0578—Polycondensates comprising silicon atoms in the main chain

Definitions

• the inventors have established a method of electrophotographic marking for use in processing conductive materials as is described in Japanese Pat. 39/ 6,079, wherein an electrophotographic layer is provided on a conductive material to be processed on which drawings of plan as well as working directions and other information are reproduced electrophotographically. Such a marking process is now being utilized in the ship building industries.
• An electrophotographic layer for use in this marking process which comprises photoconductive pulverized materials and an insulating binder must satisfy many requirements. First of all the electrophotographic layer must he possessed of excellent electrophotographic properties. Next, since the marking has to be done at an early stage of processing of the materials, the light sensitive layer must also work as a satisfactory primer coating on which an overcoating or surface coating is to be applied. This 3,552,956 Patented Jan. 5, 1971 requirement is eliminated when the marking layer is removed or dissolved off.
• Suitable compositions of ZnO in a binder layer were devised by selecting the insulating binder materials, and the ratio of the binder to the photoconductive ZnO to meet these requirements. Recently, however, a further requirement has arisen to shorten or minimize the time required for the electrophotographic marking process. It has become impossible to meet this added demand solely by improving the composition of the layer.
• the inventors have found a Way to solve this difiicult problem as a result of an extensive investigation, which makes it possible to impart improved adhesion of an electrophotographic layer to many kinds of overcoating applied thereon by subjecting it to a treatment, after the marking procedure has been completed.
• the present invention provides an improved electrophotographic marking process which is free from the shortcomings of conventional methods, and is characterized by forming on an electrically conductive or slightly conductive substrate an electrophotographic layer comprising about parts by weight of ZnO and about 40 parts by weight or less of binding material which substantially comprises an epoxy-ester resin, performing the electrophotographic procedure therewith, thus forming a visible image, then applying uniformly on the electrophotographic layer an organic solution containing filmforming material dissolved in it, the film-forming material substantially comprising an epoxy-ester resin, so as to give a thin resin film with a dried thickness of 0.5 to 10 microns.
• the principal object of the present invention is to provide a new method of marking and processing conductive materials, such as steel or many light metals used for ship building or airplane or plant construction.
• Another o'bject of the present invention is to provide a new method of toner fixation.
• An electrophotographic layer or coating mixture to form such a layer for use in electrophotographic mar-king of a structural material of a large size which is fed to a marking installation which marks at high speed and is continuously operated, must satisfy the following requirements:
• the coating mixture must be stable during prolonged storage, without causing precipitation of pigment therein or deteriorating for electrophotographic properties. Even if the precipitation of pigment occurs, it should be easily redispersed.
• the coating mixture must be adaptable to an automatic coating apparatus, and have good working properties for coating.
• the mixture must be so constituted that it provides a layer which dries sufliciently fast, showing good electrophotographic properties (i.e. high potential acceptance) as quickly as possible after coating. This requirement is very important to shorten the time required for electrophotographic marking, since ordinarily the drying step is rate-determining.
• the coated layer must be insensitive to a relatively strong pre-exposure to light before charging, i.e. it must show a rapid recovery from light fatigue.
• the electrophotographic properties of the layer should be rather insensitive to changes in relative humidity or temperature under which the layer is formed or used.
• the layer should satisfy the following requirements as a primer coating on a metal substrate:
• a binder composition comprising mainly an epoxy-ester of fatty acids of vegetable oils (epoxyester resin) can satisfy almost all of the above requirements when used as a binder for pulverized ZnO.
• Epoxy-ester resin can stably disperse ZnO particles.
• a dispersing agent such as copper Stearate, can further improve this property.
• the coating mixture comprising ZnO and epoxyester has excellent working properties for automatic coating apparatus as well as hand spraying; since this resin needs no hardening reagents or catalysts, the viscosity change in a storage tank is very small. It has little tendency to form a blushed coating under high humidity conditions.
• the drying speed of ZnO/epoxy-ester coating is remarkably influenced by the mixing ratio of ZnO to the binder; i.e. the higher the content of ZnO in the coating, the greater the drying speed of the resulting coating.
• the mixing ratio of ZnO to binder exceeds about 100130 to 25, a very rapid drying property is imparted.
• the present rapid drying property refers to the short time interval required for an electrophotographic layer to show such a high insulating property that it can serve as a hotoconductive insulating layer. This property has proved to be more closely related to the ratio of ZnO to binder than with the type of binder.
• a ZnO coating utilizing epoxy-ester resin as a binder is in general insensitive to pre-exposure when the resin, which hardens gradually under the influence of oxygen in air, is not completely hardened, provided that the purities of the ingredients of the layer are sufliciently high.
• Such a layer proved to have a potential acceptance, immediately after exposure to sunlight, of about several times ten thousand luxes for a few minutes, as high as it does when it is dark adapted.
• the resulting layer shows inferior properties under highly humid conditions; this defect, however, can be eliminated by adding a polysiloxane resin which is compatible with the epoxy-ester used. Very costly polysiloxane resin need not be used if the whole procedure of electrophotographic marking is carried out in a controlled low humidity atmosphere.
• Sensitivity to humidity is remarkably decreased when polysiloxane resin is introduced in an amount of from about 10 to 50% of the whole binder. Since polysiloxane resins generally cause deterioration of adhesive properties of the layer with other coatings, the amount should be kept as low as possible.
• the layer of the present composition shows firm adhesion with conventional primer coatings.
• the layer of the present invention failed to meet this requirement especially when the content of ZnO is high. To meet this requirement the introduction of an after-treatment is necessary.
• a layer of the present composition is rendered slightly colored by a high temperature treatment, but the degree of discoloration is permissible for successive processing. It does not generate any harmful decomposition product by such treatments.
• a ZnO/ epoxy-ester layer satisfies all the requirements except the adhesion property with overcoatings (7) and the rust preventive property (8).
• This thickness of the marking layer was about 12 to 15 microns after drying. After the volatile solvent was evaporated, the coated plate was subjected to a negative corona discharge at darkness, then exposed to light through a positive transparency. Cascade development was carried out and a positive toner image was obtained.
• sample plates thus prepared were held at room temperature for one week, then a variety of overcoatings were applied on the sample plates.
• An electrophotographic method for marking a pattern on a light sensitive layer overlying a metallic substrate which comprises electrophotographically forming a visible image on an electrophotographic recording material comprising a metallic support bearing thereon a light-sensitive layer containing about 100 parts by weight of zinc oxide and less than about parts by weight of a binder, said binder substantially comprising an epoxyester resin, uniformly applying to said layer an intermediate coating of an organic solvent solution of an epoxy-ester resin, drying said coating to provide a thin Table I Intermediate layer Drying oil Styrenated Polyvinyl overcoating None Epoxy-ester mod.
• Epoxy-ester resins used for the present invention are obtained by reacting epoxide resins and fatty acids (saturated or unsaturated) contained in many kinds of fatty oils such as dehydrated castor oil, soya oil, linseed oil, oiticica oil, tung oil, rosin, hydrated rosin, or coconut oil; they may be modified by polymerizable vinyl monomers such as styrene or acryl esters. When the content of fatty acids is high, the resulting ester can be cured by the pres ence of oxygen.
• fatty oils such as dehydrated castor oil, soya oil, linseed oil, oiticica oil, tung oil, rosin, hydrated rosin, or coconut oil
• fatty oils such as dehydrated castor oil, soya oil, linseed oil, oiticica oil, tung oil, rosin, hydrated rosin, or coconut oil
• polymerizable vinyl monomers such as
• short oil length epoxy-ester is recommended, since an oxygen cured coating sometimes causes lifting under the influence of strong solvents, such as Cellosolves, methyl ethyl ketone, or butanol used for overcoating.
• Photoconductive ZnO present in a photoconductive insulating layer has a strong tendency to decompose photocatalytically its binder material. This function is promoted by the presence of oxygen. It is found that this photocatalytic decomposition is greatly retarded as the ratio of ZnO to binder in the layer decreases. The treatment of the present invention may perhaps be considered to decrease this ratio at the surface of the layer. It should be taken into consideration that the intermediate layer is applied before the binder in the electrophotographic layer has been hardened. It is also important that the intermediate layer has a strong resistance to alkaline reagents such as ZnO. Regardless of the theory, the epoxy-ester intermediate layer proved to enhance adhesion between the ZnO/epoxy-ester layer and overcoating layers.
• the intermediate layer may be prepared in another procedure than toner fixation.
• the thin intermediate layer sometimes imparts another resin film having a dried thickness of from about 0.5 microns to about 10 microns, and further applying a protective overcoating to said thin resin film.
• said epoxy-ester resin in the binder is prepared from a dehydrated castor oil fatty acid, the oil length of which is less than 6.
• said epoxy-ester resin in said organic solvent solution is prepared from a dehydrated castor oil fatty acid, the oil length of which is less than 60%.

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• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Photoreceptors In Electrophotography (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=11579118

Family Applications (1)

Country Status (7)

• 1967
  • 1967-01-24 SE SE01051/67A patent/SE326372B/xx unknown
  • 1967-01-24 GB GB3577/67A patent/GB1155665A/en not_active Expired
  • 1967-01-24 DE DE19671522609 patent/DE1522609A1/de active Pending
  • 1967-01-25 FR FR92484A patent/FR1508918A/fr not_active Expired
  • 1967-01-25 US US611563A patent/US3552956A/en not_active Expired - Lifetime
  • 1967-01-25 BE BE693184D patent/BE693184A/xx unknown
  • 1967-07-19 NL NL6701167A patent/NL6701167A/xx unknown

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