US3401037A - Electrostatic printing on metal substrates - Google Patents
Electrostatic printing on metal substrates Download PDFInfo
- Publication number
- US3401037A US3401037A US414024A US41402464A US3401037A US 3401037 A US3401037 A US 3401037A US 414024 A US414024 A US 414024A US 41402464 A US41402464 A US 41402464A US 3401037 A US3401037 A US 3401037A
- Authority
- US
- United States
- Prior art keywords
- coating
- image
- printing
- metal substrates
- electrostatic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229910052751 metal Inorganic materials 0.000 title description 13
- 239000002184 metal Substances 0.000 title description 13
- 239000000758 substrate Substances 0.000 title description 11
- 238000000034 method Methods 0.000 description 22
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 20
- 238000000576 coating method Methods 0.000 description 20
- 239000011248 coating agent Substances 0.000 description 18
- 239000000203 mixture Substances 0.000 description 16
- 229920005989 resin Polymers 0.000 description 16
- 239000011347 resin Substances 0.000 description 16
- 229920001187 thermosetting polymer Polymers 0.000 description 16
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- 239000011787 zinc oxide Substances 0.000 description 10
- 239000007788 liquid Substances 0.000 description 9
- 229920000180 alkyd Polymers 0.000 description 8
- 238000007605 air drying Methods 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 239000008096 xylene Substances 0.000 description 5
- RBTBFTRPCNLSDE-UHFFFAOYSA-N 3,7-bis(dimethylamino)phenothiazin-5-ium Chemical compound C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 RBTBFTRPCNLSDE-UHFFFAOYSA-N 0.000 description 4
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 4
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 4
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 4
- 239000001045 blue dye Substances 0.000 description 4
- 238000009472 formulation Methods 0.000 description 4
- 239000004615 ingredient Substances 0.000 description 4
- 229960000907 methylthioninium chloride Drugs 0.000 description 4
- 239000003921 oil Substances 0.000 description 4
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- 229920001807 Urea-formaldehyde Polymers 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 239000003822 epoxy resin Substances 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 229920001568 phenolic resin Polymers 0.000 description 3
- 239000005011 phenolic resin Substances 0.000 description 3
- 229920000647 polyepoxide Polymers 0.000 description 3
- 229920001169 thermoplastic Polymers 0.000 description 3
- 229920005992 thermoplastic resin Polymers 0.000 description 3
- 239000004416 thermosoftening plastic Substances 0.000 description 3
- 239000005028 tinplate Substances 0.000 description 3
- JIGUQPWFLRLWPJ-UHFFFAOYSA-N Ethyl acrylate Chemical compound CCOC(=O)C=C JIGUQPWFLRLWPJ-UHFFFAOYSA-N 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- IISBACLAFKSPIT-UHFFFAOYSA-N bisphenol A Chemical compound C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 IISBACLAFKSPIT-UHFFFAOYSA-N 0.000 description 2
- 239000004359 castor oil Substances 0.000 description 2
- 235000019438 castor oil Nutrition 0.000 description 2
- ZEMPKEQAKRGZGQ-XOQCFJPHSA-N glycerol triricinoleate Natural products CCCCCC[C@@H](O)CC=CCCCCCCCC(=O)OC[C@@H](COC(=O)CCCCCCCC=CC[C@@H](O)CCCCCC)OC(=O)CCCCCCCC=CC[C@H](O)CCCCCC ZEMPKEQAKRGZGQ-XOQCFJPHSA-N 0.000 description 2
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 150000002924 oxiranes Chemical class 0.000 description 2
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- IMTKRLUCQZWPRY-UHFFFAOYSA-N triazine-4-carbaldehyde Chemical compound O=CC1=CC=NN=N1 IMTKRLUCQZWPRY-UHFFFAOYSA-N 0.000 description 2
- XOUAQPDUNFWPEM-UHFFFAOYSA-N 2,3,4-tris(hydroxymethyl)phenol Chemical compound OCC1=CC=C(O)C(CO)=C1CO XOUAQPDUNFWPEM-UHFFFAOYSA-N 0.000 description 1
- KUBDPQJOLOUJRM-UHFFFAOYSA-N 2-(chloromethyl)oxirane;4-[2-(4-hydroxyphenyl)propan-2-yl]phenol Chemical compound ClCC1CO1.C=1C=C(O)C=CC=1C(C)(C)C1=CC=C(O)C=C1 KUBDPQJOLOUJRM-UHFFFAOYSA-N 0.000 description 1
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 1
- CNPVJWYWYZMPDS-UHFFFAOYSA-N 2-methyldecane Chemical compound CCCCCCCCC(C)C CNPVJWYWYZMPDS-UHFFFAOYSA-N 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 1
- 241000692870 Inachis io Species 0.000 description 1
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 1
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 229920006322 acrylamide copolymer Polymers 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000001055 blue pigment Substances 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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- 238000003379 elimination reaction Methods 0.000 description 1
- 239000008098 formaldehyde solution Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- SGGOJYZMTYGPCH-UHFFFAOYSA-L manganese(2+);naphthalene-2-carboxylate Chemical compound [Mn+2].C1=CC=CC2=CC(C(=O)[O-])=CC=C21.C1=CC=CC2=CC(C(=O)[O-])=CC=C21 SGGOJYZMTYGPCH-UHFFFAOYSA-L 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- ODGAOXROABLFNM-UHFFFAOYSA-N polynoxylin Chemical compound O=C.NC(N)=O ODGAOXROABLFNM-UHFFFAOYSA-N 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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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
- G03G13/00—Electrographic processes using a charge pattern
- G03G13/22—Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20
-
- 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
- G03G5/0532—Macromolecular bonding materials obtained by reactions only involving carbon-to-carbon unsatured bonds
- G03G5/0546—Polymers comprising at least one carboxyl radical, e.g. polyacrylic acid, polycrotonic acid, polymaleic acid; Derivatives thereof, e.g. their esters, salts, anhydrides, nitriles, amides
-
- 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
- G03G5/056—Polyesters
-
- 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
- G03G5/0575—Other polycondensates comprising nitrogen atoms with or without oxygen atoms in the main chain
-
- 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
Definitions
- This invention relates to electrostatic printing and particularly to electrostatic printing on metal substrates.
- An electrostatic printing process is a process for producing a visibile image or copy by converting a light image or signal into an electrostatic charge pattern on an electrically insulating base. The charge pattern is then converted or developed into a visible image by the application thereto of electrically-attractable particles.
- a typical electrostatic printing process utilizing a photoconducting insulating stratum includes first producing a blanket electrostatic charge on the surface of the photoconducting stratum. The electrostatic charge may be stored on th surface for a time in the dark. Within the period in which a substantial charge remains, a light image is focused on the charged surface, discharging the portions of the surface irradiated with light, leaving the remainder of the surface in a charged condition, and thereby forming an electrostatic image thereon.
- the electrostatic image is rendered visible by applying to the electrostatic image a developer substance, such as a pigmented thermoplastic resin powder, which is held electrostatically to the charged areas of the surface.
- a developer substance such as a pigmented thermoplastic resin powder
- the visible image thus formed may be fixed directly to the surface, for example, by fusing the image thereto.
- thermoplastic resin powder A process of electrostatic printing in which the thermoplastic resin powder is fused directly to the surface of the stratum is described in US. Patents 3,052,539 and 3,052,540, both to H. G. Greig.
- thermosetting binders have been considered in place of the thermoplastic binders. However, these thermosetting binders have always been heated to effect'at leasta substantial portion of crosslinking or setting and usually a complete setting prior to the forming and printing of the image.
- thermosetting protective overcoating when the el ctrostatic printing is done in the manner described above, a thermosetting protective overcoating must be applied or else the printed matter lacks abrasion resistance, being easily removed or marred by handling.
- thermosetting overcoating We have now discovered a novel method of electrostatic printing on metal substrates which eliminates the need for the thermosetting overcoating.
- Our method involves providing the metal substrate with a coating comprising a dispersion of photoconductive Zinc oxide in an electrically insulating solution in a volatile organic solvent of an electrically insulating thermosetting resin which does not cross-link on air-drying.
- a coating comprising a dispersion of photoconductive Zinc oxide in an electrically insulating solution in a volatile organic solvent of an electrically insulating thermosetting resin which does not cross-link on air-drying.
- air-drying is meant permitting the solvent to evap rate at the ambient temperature.
- the resin must be one which requires heat in order to under.- go any degree of setting.
- Such resins are well known to those skilled in the art. While air drying is the preferred method of eliminating the solvent, the elimination of solvent may also be carried out at elevated temperatures if the temperature is sufliciently low enough to prevent any appreciable cross-linking of the resin.
- the applied coating is air-dried to a tack-free, uncrosslinked film.
- the coated plate is then charged and eX- posed to the image in the conventional manner.
- the developer is applied conventionally. After the application of the developer, the developed coating is heated for the temperature and time required to set the particular thermosetting resin binder.
- the resulting coated panel has the printed or developed matter firmly fixed. The rub resistance is excellent. The panel may be bent and otherwise worked without affecting the printing.
- the zinc oxide particles are conventional photoconductive zinc oxide particles of the type described in the aforementioned Greig patents.
- the binder resins must be thermosetting and electrically insulating. That is they must have high dielectric strengths of the same order as those of the thermoplastic resins described in said Greig patents.
- the thermosetting resin must be one which while air-drying to a tack-free film does not undergo any cross-linking unless heat is applied.
- Classes of this type of thermosetting resin are well known in the art. They include ureaformaldehyde resins, triazine-formaldehyde resins, phenolic resins, epoxy resins, methylolated acrylamide resins, styrenated alkyds and m'ethacrylated alkyds.
- the coated panels are often piled in stacks prior to printing. Accordingly, it is preferable that the coatings have good block resistance.
- Block resistance is determined by placing the coated surfaces of two panels face to face and applying a given pressure per unit area at a given temperature. If the surfaces do not stick together, then the coating is said to have a block resistance greater than the appled pressure at the temperature. When the panels are to be stacked during the printing process, it is preferable that the coatings have a block resistance greater than 1.5 lbs./ sq. in. at 25 C.
- the developers used in this invention are preferably liquid developers.
- Conventional liquid developers e.g., the
- liquid developers of Patent No. 2,907,674 which are' charged particles dispersed in an insulating liquid of high volume resistivity e.g., toluene, cyclohexane, n-pentane and carbon tetrachloride may be used.
- insulating liquid of high volume resistivity e.g., toluene, cyclohexane, n-pentane and carbon tetrachloride
- Other suitable liquid developers are those described in Patent No. 3,078,231.
- a dispersion of 1 g. of peacock blue pigment in 9 g. of mineral oil is in turn dispersed in 10,000 ml.
- the developed image appears as blue printing on the white background.
- the panel is then baked at 350 F. for /2 hour to cure the thermosetting coating and to fuse the deposited developer to the coating.
- the coating is hard, tough and well cured, and the developer which is incorporated into the cured coating displays excellent ad hesion and rub-resistance.
- Methylon 75108 Phenolic resin consisting of a mixture of the alkyl ethers of mono-, diand trimethylol phenol, the tri-component predominating, prepared in accordance with US. Patent No. 2,579,330, par- A 1:1 mixture of toluene and ethyl acetate in an amount sufficient to reduce the viscosity of the composition to 25 seconds on a Ford No. 4 Cup.
- Epon 1007 epoxy resin, formed by the reaction of epichlorohydrin and Bisphenol A, having an average molecular weight of 2625, an epoxide equivalent weight of l5502200, a hydroxyl equivalent weight of 200 and 1.3 to 1.7 epoxides per molecule
- Epon 1007 epoxy resin, formed by the reaction of epichlorohydrin and Bisphenol A, having an average molecular weight of 2625, an epoxide equivalent weight of l5502200, a hydroxyl equivalent weight of 200 and 1.3 to 1.7 epoxides per molecule
- Zinc oxide (photoconductive) 50 0.12% solution in methanol of methylene blue dye 2.0
- Styrenated 60% oil length phthalic alkyd resin having a 1:1, styrenezmodified alkyd content, the oil modifying the alkyd being a 1:1, soya-dehydrated castor oil blend Zinc oxide (photoconductive) 50 0.12% solution in methanol of methylene blue dye 2.0 and, xylene, in an amount sufficient to reduce the viscosity of the composition to 25 seconds on a Ford No. 4 Cup.
- the process of this invention may be used on a wide variety of metal substrates such as aluminum, copper, brass and steel plates.
- a process for forming a visible image on metal substrates consisting of the steps of (A) coating a surface of the metal substrate with a composition comprising a dispersion of photo-conductive zinc oxide in an electrically insulating filmforming thermosetting resin, selected from the group consisting of urea-formaldehyde resins, triazineformaldehyde resins, phenolic resins, epoxy resins, methylolated acrylamide resins, styrenated alkyds and methacrylated alkyds, which does not cross-link on air-drying in a volatile organic solvent,
- thermosetting resinous film then simultaneously fixing the deposited developer and setting said thermosetting resinous film by heating at 350 F. for 30 minutes.
- thermosetting resin is one which gives uncross-linked films upon airdrying having a block resistance greater than 1.5 1bs./sq. in. at 25 C.
- the resin is a copolymer comprising the polymerization product of 75% styrene, 15% acrylamide, 7% ethyl acrylate and 3% methacrylic acid.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Photoreceptors In Electrophotography (AREA)
Description
United States Patent 3,401,037 ELECTROSTATIC PRINTING 0N METAL SUBSTRATES Jerome Roteman, Freehold, N.J., and Sebastian T. Brancato, Queens Village, N.Y., assignors to Interchemical Corporation, New York, N.Y., a corporation of Ohio No Drawing. Filed Nov. 25, 1964, Ser. No. 414,024 5 Claims. (Cl. 96-1) ABSTRACT OF THE DISCLOSURE An electrostatic printing process for developing a visible image on a metal substrate carrying a coating comprising a dispersion of photoconductive zinc oxide in a vehicle of an electrically insulated, air-dried, tack free, uncross-linked film of a thermosetting resin in a volatile organic solvent. The coated film is charged and the image formed in the conventional manner. The image is developed and the film simultaneously cured by exposure to heat.
This invention relates to electrostatic printing and particularly to electrostatic printing on metal substrates.
An electrostatic printing process is a process for producing a visibile image or copy by converting a light image or signal into an electrostatic charge pattern on an electrically insulating base. The charge pattern is then converted or developed into a visible image by the application thereto of electrically-attractable particles. A typical electrostatic printing process utilizing a photoconducting insulating stratum includes first producing a blanket electrostatic charge on the surface of the photoconducting stratum. The electrostatic charge may be stored on th surface for a time in the dark. Within the period in which a substantial charge remains, a light image is focused on the charged surface, discharging the portions of the surface irradiated with light, leaving the remainder of the surface in a charged condition, and thereby forming an electrostatic image thereon. The electrostatic image is rendered visible by applying to the electrostatic image a developer substance, such as a pigmented thermoplastic resin powder, which is held electrostatically to the charged areas of the surface. The visible image thus formed may be fixed directly to the surface, for example, by fusing the image thereto.
A process of electrostatic printing in which the thermoplastic resin powder is fused directly to the surface of the stratum is described in US. Patents 3,052,539 and 3,052,540, both to H. G. Greig.
Attempts have been made to utilize recording elements of the type described in the Greig patents in printing on tinplate and other metal substrates with less than fully desirable results. In such methods, photoconductive zinc oxide particles are usually dispersed in an electrically insulating thermoplastic binder and coated on the metal substrate. The electrostatic image is then formed and developed or printed, after which a clear thermosetting protective overcoating is applied. There have been some instances where thermosetting binders have been considered in place of the thermoplastic binders. However, these thermosetting binders have always been heated to effect'at leasta substantial portion of crosslinking or setting and usually a complete setting prior to the forming and printing of the image.
Irrespective of whether the binder is thermoplastic or thermosetting, we have found that when the el ctrostatic printing is done in the manner described above, a thermosetting protective overcoating must be applied or else the printed matter lacks abrasion resistance, being easily removed or marred by handling.
We have now discovered a novel method of electrostatic printing on metal substrates which eliminates the need for the thermosetting overcoating.
Our method involves providing the metal substrate with a coating comprising a dispersion of photoconductive Zinc oxide in an electrically insulating solution in a volatile organic solvent of an electrically insulating thermosetting resin which does not cross-link on air-drying. (By air-drying, is meant permitting the solvent to evap rate at the ambient temperature.) In other words, the resin must be one which requires heat in order to under.- go any degree of setting. Such resins are well known to those skilled in the art. While air drying is the preferred method of eliminating the solvent, the elimination of solvent may also be carried out at elevated temperatures if the temperature is sufliciently low enough to prevent any appreciable cross-linking of the resin.
The applied coating is air-dried to a tack-free, uncrosslinked film. The coated plate is then charged and eX- posed to the image in the conventional manner. The developer is applied conventionally. After the application of the developer, the developed coating is heated for the temperature and time required to set the particular thermosetting resin binder. The resulting coated panel has the printed or developed matter firmly fixed. The rub resistance is excellent. The panel may be bent and otherwise worked without affecting the printing.
The zinc oxide particles are conventional photoconductive zinc oxide particles of the type described in the aforementioned Greig patents.
The binder resins must be thermosetting and electrically insulating. That is they must have high dielectric strengths of the same order as those of the thermoplastic resins described in said Greig patents. In addition, the thermosetting resin must be one which while air-drying to a tack-free film does not undergo any cross-linking unless heat is applied. Classes of this type of thermosetting resin are well known in the art. They include ureaformaldehyde resins, triazine-formaldehyde resins, phenolic resins, epoxy resins, methylolated acrylamide resins, styrenated alkyds and m'ethacrylated alkyds.
During the printing of metals which are to be used in cans and containers, the coated panels are often piled in stacks prior to printing. Accordingly, it is preferable that the coatings have good block resistance.
Block resistance is determined by placing the coated surfaces of two panels face to face and applying a given pressure per unit area at a given temperature. If the surfaces do not stick together, then the coating is said to have a block resistance greater than the appled pressure at the temperature. When the panels are to be stacked during the printing process, it is preferable that the coatings have a block resistance greater than 1.5 lbs./ sq. in. at 25 C.
The developers used in this invention are preferably liquid developers. Conventional liquid developers e.g., the
liquid developers of Patent No. 2,907,674 which are' charged particles dispersed in an insulating liquid of high volume resistivity e.g., toluene, cyclohexane, n-pentane and carbon tetrachloride may be used. Other suitable liquid developers are those described in Patent No. 3,078,231.
While the preferred embodiments of this invention have been described in terms of liquid developers, it should be clear that the conventional powder developers may be used in place of the liquid developers. When powders are used the exposure and printing procedures of US. Patent No. 3,052,539 as well as the powder developers described in said patent may be used.
The following examples will further illustrate the practice of this invention. Unless otherwise set forth, all proportions in this specification and claims are by weight.
3 EXAMPLE 1- The following mixtureis ball milled to a smooth consistency:
Parts by weight A 48% solution in 1:1 xylene: butanol solvent of butoxy-methylolated acrylamide copolymer consisting of the reaction product of a 30% solution of formaldehyde in butanol with a copolymer of 75% styrene, acrylamide, 7% ethyl acrylate and 3% methacrylic acid; the formaldehyde solution: copolymer ratio is 1:3 Zinc oxide (photoconductive) A 0.12% solution in methanol of methylene blue dye 2.0
Then, sulficient xylene is added to reduce the viscosity of the mixture to 25 sec. on a Ford No. 4 Cup. The mixture is then sprayed by conventional apparatus on to tinplate panel and permitted to air-dry at the ambient temperature for about 2 to 3 hours. The resulting white coating is tack-free and has block resistance of about two pounds per square inch at room temperature. In order to print on the panel electrostatically, the coating on the panel is charged negatively in accordance with the procedure of US. Patent No. 2,907,674 and exposed to a positive transparency of the image to be printed. Then, following the procedure of said patent, a liquid developer of the following composition is applied to the plate:
A dispersion of 1 g. of peacock blue pigment in 9 g. of mineral oil is in turn dispersed in 10,000 ml. Isopar G solvent containing 7 g. of manganese naphthenate (aliphatic hydrocarbon solvent having a boiling range of 315-350 F. and a K. B. Value of 27.4.)
The developed image appears as blue printing on the white background. The panel is then baked at 350 F. for /2 hour to cure the thermosetting coating and to fuse the deposited developer to the coating. The coating is hard, tough and well cured, and the developer which is incorporated into the cured coating displays excellent ad hesion and rub-resistance.
EXAMPLE 2 Example 1 is repeated using the same procedure conditions, ingredients and proportions except that in the coating, the following formulation is used:
Parts by weight Methylon 75108 (Phenolic resin consisting of a mixture of the alkyl ethers of mono-, diand trimethylol phenol, the tri-component predominating, prepared in accordance with US. Patent No. 2,579,330, par- A 1:1 mixture of toluene and ethyl acetate in an amount sufficient to reduce the viscosity of the composition to 25 seconds on a Ford No. 4 Cup.
The results are substantially the same as in Example 1.
EXAMPLE 3 Example 1 is repeated using the same procedure, conditions, ingredients and proportions except that in the coating, the following formulation is used:
Parts by weight Epon 1007 (Epoxy resin, formed by the reaction of epichlorohydrin and Bisphenol A, having an average molecular weight of 2625, an epoxide equivalent weight of l5502200, a hydroxyl equivalent weight of 200 and 1.3 to 1.7 epoxides per molecule Urea-formaldehyde 30 Zinc oxide (photoconductive) 50 0.12% solution in methanol of methylene blue dye 2.0
and, A 1:1 mixture of xylene and methyl isobutyl ketone in an amount sufiicient to reduce the viscosity of the composition to 25 seconds on a Ford No. 4 Cup.
The results are substantially the same as in Example 1.
EXAMPLE 4 Example 1 is repeated using the same procedure, conditions, ingredients and proportions except that in the coating, the following formulation is used:
Parts by weight Styrenated 60% oil length phthalic alkyd resin having a 1:1, styrenezmodified alkyd content, the oil modifying the alkyd being a 1:1, soya-dehydrated castor oil blend Zinc oxide (photoconductive) 50 0.12% solution in methanol of methylene blue dye 2.0 and, xylene, in an amount sufficient to reduce the viscosity of the composition to 25 seconds on a Ford No. 4 Cup.
The results are substantially the same as in Example 1.
EXAMPLE 5 Example 1 is repeated using the same procedure, conditions, ingredients and proportions, except that in the coating, the following formulation is used:
Parts by weight A methacrylated 30% oil length alkyd resin, the methyl methacrylate content of which is 35% and the modifying oil of which is dehydrated castor oil 100 Zinc oxide (photoconductive) 50 0.12% solution in methanol of Methylene Blue dye 2.0 and, Xylene in an amount sufficient to reduce the viscosity of the composition to 25 seconds on a Ford No. 4 Cup.
The results are substantially the same as in Example 1.
In addition to tin-plate as described in the examples, the process of this invention may be used on a wide variety of metal substrates such as aluminum, copper, brass and steel plates.
While there have been described what is at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.
We claim:
1. A process for forming a visible image on metal substrates consisting of the steps of (A) coating a surface of the metal substrate with a composition comprising a dispersion of photo-conductive zinc oxide in an electrically insulating filmforming thermosetting resin, selected from the group consisting of urea-formaldehyde resins, triazineformaldehyde resins, phenolic resins, epoxy resins, methylolated acrylamide resins, styrenated alkyds and methacrylated alkyds, which does not cross-link on air-drying in a volatile organic solvent,
(B) air-drying the applied coating to a tack-free uncross-linked film,
(C) forming a pattern of electrostatic charges corresponding to said image on the surface of said coating,
(D) developing said pattern by depositing a finelydivided developer substance on the surface bearing said pattern in a configuration conforming with said pattern, and
5 (E) then simultaneously fixing the deposited developer and setting said thermosetting resinous film by heating at 350 F. for 30 minutes.
2. The process of claim 1, wherein the developer is a dispersion of finely-divided charged pigment particles in an electrically insulating liquid.
3. The process of claim 1, wherein the thermosetting resin is one which gives uncross-linked films upon airdrying having a block resistance greater than 1.5 1bs./sq. in. at 25 C.
4. The process of claim '1, wherein the resin is a copolymer comprising the polymerization product of 75% styrene, 15% acrylamide, 7% ethyl acrylate and 3% methacrylic acid.
plate.
6 References Cited UNITED STATES PATENTS Van Dorn et al 961.8 Kucera 961.8 Semegen 117-76 Middleton et al 96-15 Metcalfe et a1 961 Wolff u 96-l.8 Sciambi 961.5 Gray 961.5 Fox 96--1.5
NORMAN G. TORCHIN, Primary Examiner. 5. The proces of claim 1, wherein said metal is tin- 15 C. E, VAN HORN, Assistant Examiner.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US414024A US3401037A (en) | 1964-11-25 | 1964-11-25 | Electrostatic printing on metal substrates |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US414024A US3401037A (en) | 1964-11-25 | 1964-11-25 | Electrostatic printing on metal substrates |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3401037A true US3401037A (en) | 1968-09-10 |
Family
ID=23639649
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US414024A Expired - Lifetime US3401037A (en) | 1964-11-25 | 1964-11-25 | Electrostatic printing on metal substrates |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3401037A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3519421A (en) * | 1967-09-26 | 1970-07-07 | Gaf Corp | Electrophotographic recording material |
| US3620729A (en) * | 1969-08-28 | 1971-11-16 | Nat Starch Chem Corp | Electrophotographic coating compositions employing styrene terpolymers as binders |
| US3671646A (en) * | 1968-07-27 | 1972-06-20 | Mitsubishi Paper Mills Ltd | Liquid developers for electrostatic photography |
| US4105448A (en) * | 1974-08-23 | 1978-08-08 | Fuji Photo Film Co., Ltd. | Electrophotographic photosensitive layer and marking method |
| US4748099A (en) * | 1978-02-07 | 1988-05-31 | Konishiroku Photo Industry Co., Ltd. | Process for forming printing plate using an electrophotographic material for obtaining toner image |
| US20130017405A1 (en) * | 2010-05-28 | 2013-01-17 | The Johns Hopkins University | Self-Healing Coatings |
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|---|---|---|---|---|
| US2937944A (en) * | 1957-11-20 | 1960-05-24 | Haloid Xerox Inc | Xerographic light-sensitive member and process therefor |
| US2959481A (en) * | 1958-12-18 | 1960-11-08 | Bruning Charles Co Inc | Electrophotographic recording member and process of producing same |
| US2973284A (en) * | 1957-04-30 | 1961-02-28 | Goodrich Co B F | Leather-like material |
| US3121006A (en) * | 1957-06-26 | 1964-02-11 | Xerox Corp | Photo-active member for xerography |
| US3174855A (en) * | 1961-02-23 | 1965-03-23 | Xerox Corp | Method for a production of a xerographic plate |
| US3197043A (en) * | 1962-03-15 | 1965-07-27 | Brewster Machine Co | Bale buncher attachment for hay balers |
| US3226227A (en) * | 1960-09-02 | 1965-12-28 | Rca Corp | Method of producing a solvent-resistant pattern using developed electrostatic image formation techniques |
| US3231374A (en) * | 1960-09-02 | 1966-01-25 | Rca Corp | Methods for preparing etch resists using an electrostatic image developer composition |
| US3240597A (en) * | 1961-08-21 | 1966-03-15 | Eastman Kodak Co | Photoconducting polymers for preparing electrophotographic materials |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2973284A (en) * | 1957-04-30 | 1961-02-28 | Goodrich Co B F | Leather-like material |
| US3121006A (en) * | 1957-06-26 | 1964-02-11 | Xerox Corp | Photo-active member for xerography |
| US2937944A (en) * | 1957-11-20 | 1960-05-24 | Haloid Xerox Inc | Xerographic light-sensitive member and process therefor |
| US2959481A (en) * | 1958-12-18 | 1960-11-08 | Bruning Charles Co Inc | Electrophotographic recording member and process of producing same |
| US3226227A (en) * | 1960-09-02 | 1965-12-28 | Rca Corp | Method of producing a solvent-resistant pattern using developed electrostatic image formation techniques |
| US3231374A (en) * | 1960-09-02 | 1966-01-25 | Rca Corp | Methods for preparing etch resists using an electrostatic image developer composition |
| US3174855A (en) * | 1961-02-23 | 1965-03-23 | Xerox Corp | Method for a production of a xerographic plate |
| US3240597A (en) * | 1961-08-21 | 1966-03-15 | Eastman Kodak Co | Photoconducting polymers for preparing electrophotographic materials |
| US3197043A (en) * | 1962-03-15 | 1965-07-27 | Brewster Machine Co | Bale buncher attachment for hay balers |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3519421A (en) * | 1967-09-26 | 1970-07-07 | Gaf Corp | Electrophotographic recording material |
| US3671646A (en) * | 1968-07-27 | 1972-06-20 | Mitsubishi Paper Mills Ltd | Liquid developers for electrostatic photography |
| US3620729A (en) * | 1969-08-28 | 1971-11-16 | Nat Starch Chem Corp | Electrophotographic coating compositions employing styrene terpolymers as binders |
| US4105448A (en) * | 1974-08-23 | 1978-08-08 | Fuji Photo Film Co., Ltd. | Electrophotographic photosensitive layer and marking method |
| US4748099A (en) * | 1978-02-07 | 1988-05-31 | Konishiroku Photo Industry Co., Ltd. | Process for forming printing plate using an electrophotographic material for obtaining toner image |
| US20130017405A1 (en) * | 2010-05-28 | 2013-01-17 | The Johns Hopkins University | Self-Healing Coatings |
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