Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D209/00—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
  • C07D209/02—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/494—Silver salt compositions other than silver halide emulsions; Photothermographic systems ; Thermographic systems using noble metal compounds
  • G03C1/498—Photothermographic systems, e.g. dry silver
  • G03C1/4989—Photothermographic systems, e.g. dry silver characterised by a thermal imaging step, with or without exposure to light, e.g. with a thermal head, using a laser
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/913—Material designed to be responsive to temperature, light, moisture
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S430/00—Radiation imagery chemistry: process, composition, or product thereof
  • Y10S430/165—Thermal imaging composition
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
  • Y10T428/273—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.] of coating
  • Y10T428/277—Cellulosic substrate

Definitions

• This invention relates to heat-sensitive compositions and elements embodying them that are useful in thermographic recording and copying systems. More particularly, it relates to such compositions and elements which upon exposure to heat darken in color and undergo the further transformation whereby the water-soluble components become water-insoluble. Still more particularly, this invention relates to heat-sensitive flexible sheets bearing coatings containing such compositions.
• Heat-sensitive paper for use in a thermographic apparatus giving copies of certain graphic originals quickly and easily by a completely dry process is commercially available.
• the primary shortcomings of this paper (which has enjoyed considerable commercial use) are (1) its limited resolving power due to the granular structure of the heat-sensitive components, and (2) the narrow exposure latitude. Other disadvantages are the unattractive appearance of the finished copy caused by the uppleasant combinations of image and background color, the thermal instability of the paper after it is used for making copies and the undesirably high flexibility of the material.
• An object of this invention is to provide a heat-sensitive element which is capable of forming rapidly, by a dry thermographic process, an image having high resolving power.
• a further object is to provide such a product which provides wide exposure latitude.
• compositions of this invention comprise an intimate mixture of (1) A S-hydroxy-3-pyrrolin-2-one, having a negative substituent in the 3-position, of the general formula:
• R is a member selected
• a small amount of a metal salt taken from the group consisting of cupric, ferrous, mercuric and silver salts of a monoor dibasic organic carboxylic acid, and if desired,
• the metal salt is a cupric salt of an organic carboxylic acid of not more than4 carbon atoms which is either unsubstituted or may be substituted by halogen, e.g., fluorine, chlorine and bromine, hydroxyl, amino or alkylamino of 1-4 carbon atoms.
• halogen e.g., fluorine, chlorine and bromine
• hydroxyl, amino or alkylamino of 1-4 carbon atoms can be made by merely admixing the compounds and, if desired, a solvent or diluent and a polymeric binding agent, e.g., a natural or synthetic water-permeable colloid having protective colloid properties, e.g., gelatin and polyvinyl alcohol.
• the novel heat-sensitive copy of recording elements of the invention comprise a suitable support having an outer surface coated or impregnated with the aforesaid compositions.
• the supports can be rigid, e.g., glass, plastic plates, or cardboard, or they can be flexible, e.g., paper or a polymeric film. Flexible supports are preferred.
• the support for the thermally sensitive, permanent imagerecording elements of the invention can vary widely in constitution but should not be a good conductor of heat because the image is produced thermally and a heat-conductive support, e.g., a metal foil or a self-supporting film or layer containing an appreciable quantity of powdered metal, would precent the formation of a sharp image.
• the flexible support can be composed of an organic polymeric material having a softening point above the temperature at which the thermographic image is formed, e.g., above l20200 C.
• Suitable such polymen'c materials include paper, thin cardboard, self-supporting films composed of cellulose and regenerated cellulose; cellulose others, eg., methyl cellulose, ethyl cellulose of low substitution; cellulose esters, e.g., cellulose triacetate; synthetic macro-molecular polymers, including polyvinyl acetals, e.g., polyvinyl formal; polyvinyl esters, e.g., polyvinyl acetate of low acetate content, and proteins, e.g., gelatin.
• the foregoing synthetic polymers can be layers on paper or another support.
• the supports can be used in the form of films and in the form of felted sheets made from fibers of the cellulosic or other polymeric materials referred to above.
• heat-sensitive layer containing 5-hydroxy-3-pyrro1in-2-one and Cu, Fe, Hg or Ag salt of monoor dibasic organic carboxylic acid Support, e.g., paper or polymeric film
• the flexible sheet support should be infrared-transparent to permit the formation of the color image in depth and in, for instance, reflex copying to permit the satisfactory development of the image on the reverse surface or within the sheet.
• the flexible sheet support can be infrared opaque.
• the flexible sheet support can be transparent or opaque to visible light.
• the optimum ratio of the hydroxypyrrolinone and metal salt will dependupon the type of product desired but, in general, the preferred range is considered to be 0.1 to 0.5 mols of the metal salt per mol of the substituted hydroxypyrrolinone compound with a useful range extending from 0.01 to 1.0 mols of metal salt per mol of the substituted hydroxypyrrolinone.
• Increasing the relative concentration of metal salt increases the speed of the thermochemical reaction but this may be at the expense of higher background density or stain depending on the particular metal ion employed. This background is, of course, no problem when the print can be washed.
• Thermographic speed also is increased by increasing total coating weight of the heat-sensitive materials.
• Useful hydroxypyrrolinone coating weights are in the range 20-5 mg./dm. depending on intended application, while the preferred coating weight range is 50-200 mg./dm.
• an aqueous solution of 3-cyano-4,5dimethyl- 5-hydroxy-3-pyrrolin-2-one and cupric acetate are coated on paper or other suitable base material and exposed as described in C. S. Miller U.S. Patent 2,740,896 of April 3, 1956, in a commercial Thermo-Fax (made by Minnesota Mining and Manufacturing Co.) thermographic copying machine, whereby there is produced a copy of a graphic original, said copy having an intense dark-colored, grainless, high resolution image against a light-colored badground.
• EXAMPLE 1 3-cyano-4,5-dirnethyl-5-hydroxy-3-pyrrolin-2-one 104 mg.) and 34.2 mg. of Cu(CH COO) -H O were dissolved in 4 ml. of water at room temperature and, after standing for 1 hour, the solution was brush-coated onto a 4" x 4" piece of onionskin paper (Eagle-A Trojan). The coating, after being air-dried at room temperature, was exposed at the No. 1 setting of a Premier Model 19 Thermo-Fax (Minnesota Mining and Manufacturing Co.) thermographic copying machine to produce a copy of a paper sheet on which letter characters were printed in carbon black ink, said copy having a coal black image against a light colored background.
• a Premier Model 19 Thermo-Fax Minnesota Mining and Manufacturing Co.
• Example III in Example II were mixed, the resulting solution allowed to stand for 1 hour at room temperature, spread out over the surface of a 2" x 2" area of the treated film base. and then air dried at room temperature to yield a smooth, transparent coating. The coating was exposed as described in Example I to yield a copy having a coal black image against a light colored background.
• Another portion of the coating was dipped for 30 seconds in water, drained, and then dipped for 10 seconds in 0.1 M HCl solution, followed by a 30-second water wash. It was then air dried. The background was a pure white, while the image remained a coal black. Heating at 180 C. up to 1 minute had no efiect on the copy so treated.
• EXAMELE VI A solution of 0.25 g. of 3-cyano-4,S-dimethyl-S-hydroxy-3-pyrrolin-2-one in 3 ml. of water was mixed with 0.15 ml. of 0.3 M Cu(CH COO) solution to give a Cu +/hydroxypyrrolinone mol ratio of 0.027.
• the miX- ture was coated fresh on a 5 x 8 /2 inch piece of onionskin paper and air dried. Its sensitivity was tested by heating a small disk of the coating on a Fisher melting point apparatus, the temperature of the metal block being read by a thermometer whose bulb was inserted inside the block. The coating darkened somewhat after holding 20 seconds at 150 C. and was a dark gray-black after 20 seconds at 180 C.
• thermographic sensitivity is shown in tabular form below.
• Example II After drying in air at room temperature, the four coated papers were exposed as in Example I to yield copies having coal black images against light-colored backgrounds. The four coatings were roughly equivalent in thermographic sensitivity.
• EXAMPLE V-IH One gram of a solution of polyvinyl alcohol as described in Example 11 was coated on a 2" x 3" piece of tracing paper (Albanene) and air-dried at room temperature. A mixture of 0.25 ml. of an aqueous l M solution of 3-cyano-4,S-dimethyl-S-hydroxy-3-pyrrolin-2- one and 0.60 ml. of an aqueous 0.1 M solution of mercuric acetate was allowed to stand overnight and then flowed over the surface of the polyvinyl alcohol treated tracing paper. After air drying at room temperature, the coating was exposed as in Example I to yield a copy having a dark purple image against :a light pink background.
• Example VIII A mixture of 0.80 ml. of the 0.0725 M AgOCOCH solution and 0.25 ml. of an aqueous l M Solution of 3-cyano-4,5-dimethyl-5-hydroxy-3-pyrrolin-2-one was coated on a polyvinyl alcohol treated tracing paper support described in Example VIII. With drying and exposure as described in Example I, there was formed a copy having a dark brown image against a lighter brown background.
• thermographic exposure A similar coating upon appreciable exposure to room light showed indications of photolysis so that with such a coating it is desirable to provide for protection against excessive exposure to light prior to the thermographic exposure.
• the fixing step following thermographic exposure is particularly recommended for a coating containing silver.
• EXAMPLE XI which was added an amount of the solution or suspension containing 0.1 millimol of the respective copper salt. These mixtures were coated on 3" x 4" pieces of onionskin paper and air dried at room temperature. Each of the respective coated papers showed some color changev when heated for 15-30 sec. at C. and turned black upon heating for the same length of time at 180 C.
• EXAMPLE m1 Approximately 41.5 mg. (0.25 millimol) of 3-cyano-(4,5-methyl, ethyl)-5-hydroxy-3-pyrrolin-2-one was dissolved in 2 ml. ethanol. To this solution was added 0.15 ml. of 0.3 M Cu(CH COO) solution and the mixture coated fresh on a 2 X 3" piece of onionskin paper. After air-drying the coating was exposed to a printed paper sheet in the Thermo-Fax machine described in Example I. Three exposure passes at setting No. 1 produced a faint black image on a light blue-green background.
• Procedure B To make copper propionate, one-half of the Cu(OH) precipitate from Procedure A was mixed with 1.80 ml. of propionic acid and the mixture diluted to 50 ml. with water to make a 0.5 M suspension. Additional propionic acid was required to dissolve all the Cu(QH) forming a clear green solution.
• Procedure C To make copper chloroacetate, one-half of the Cu(OH) precipitate from Procedure A was mixed with a solution of 2.30 grams chloroacetic acid in 25 ml. H O. The mixture, also a suspension, was diluted to 50 ml. with water. Additional chloroacetic acid was required to dissolve all the Cu(OH) Procedure D.To make copper glycinate, 0.02 mole of Cu(OH) was prepared as described in Procedure A to which was added a solution of 1.50 g. glycine dissolved in 25 ml. H O. The slurry was diluted to 100ml. with P1 0. A few drops of cone. HCl was added to help dissolve the suspension.
• Procedure F -Copper trifiuoroacetate was prepared by mixing 0.02 mole of Cu(OH) with 1.49 ml. triiluoroacetic acid followed by dilution to 100' ml. with H O. No attempt was made to dissolve the small portion of Cu(OH) that did not dissolve.
• thermographic image in the new elements of the present invention can be achieved in any way whereby the element comprising the flexible sheet support and in operative association therewith the hydroxypyrrolinone and metal salt is selectively exposed to the required color-developing temperatures to form the desired pattern.
• the thermographic element can be pressed with a heated stylus operated manually or mechanically as the recording or copy arm of a sensing system driven by a photoelectric scanning beam.
• thermographic element In a similar fashion, heated type characters, slugs, or cornplete composed plates may be pressed directly in contact with the thermographic element.
• the therinog'raph'ic images can be prepared by suitable selective infrared absorption.
• a master to be reproduced will generally have a dark text on a white background. Accordingly, on exposure to infrared radiation or to normal light, the black areas are selectively warmer than the white areas by virtue of the selective absorption of the infrared radiation in the dark areas.
• the original With light of suflicient intensity directed on such an original held in contact with one of the thermographic elements of the present invention, the original is heated in the dark areas to temperature ranges wherein the thermographic reaction occurs in the therrnographic element, thereby producing a colored direct positive duplicate of the original.
• thermographic elements The temperatures to which these thermographic elements must be brought in order to develop the thermographic image will vary with the specific substituted hydroxypyrroiinone, the nature of the support, the relative concentration of the hydroxypyrrolinone, the specific metal ion and the amount of such ion. Generally satisfactory colored images are obtained when the thermographic element is brought to temperatures between about 120 C. and about 200 C. A generally satisfactory average temperature would thus be in the neighborhood of about 140170 C.
• the times at which these thermographic elements must be selectively held at such temperatures in order to develop satisfactory image quality likewise vary with the nature of the substituents on the hydroxypyrrolinone, themetal salt and in part with the nature of the support in the sense of the optical contrast qualities thereof.
• An approximate shortest color development time at these temperatures is in the neighborhood of about 0.1-2.0 seconds; whereas, with some of the less reactive mixtures of lower heat sensitivity, reaction times of up to 1015 seconds or even a minute are needed.
• an average color development time at the average development temperature of about 175 C. will be about 1.0 to 2.0 seconds.
• thermographic copying paper for example as a general copying paper.
• the elements are also useful as a thermogr'aphic microfilm, for making copies via enlargement or reduction projection and for use in recording information in recording instruments, e.g., spectrograms.
• This invention has the advantage that it provides thermally-sensitive recording elements of high potential resolving power since it is a grainless system as contrasted with the non-grainless commercially available systems described in US. 2,663,654 through 2,663,657. Exposure latitude of the element is unusually broad. This invention makes possible the production of a copy which is pleasing to the eye, giving an intense black image against a white of light-colored background.
• Another advantage of the present invention is that it provides the art with a new class of thermally sensitive image recording elements which are economical to make and easy to use in making positive images directly.
• the novel elements do not require skilled operators or technicians when used to make positive images. A large number of reproductions can be made rapidly from any printed or other material'to be copied.
• Another advantage is that the novel elements can be readily fixed to remove discoloration and obtain a white background bywashing in wateror dilute mineral. acid (e.g., hydro"- chloric solutions). Still other advantages will be apparent to those skilled in the art of image formation or reproduction.
• the novel thermally-sensitive recording elements of this invention have advantages over prior art elements when used in charts to be marked with a stylus.
• the latter generally employ a dark-colored paper with a white, opaque coating that becomes clear on application of heat, thereby producing a dark area on a white background.
• Typical coatings of this type are based on opaque, waxy, or crystalline materials, blushed resin coatings (see U.S. Patent 2,519,660) or plastic films coritaining microscopic voids (see US. Patent 2,739,909). Waxy coatings stick to adjacent layers and because of their softness are easily damaged. The blushed resin coatings must be applied under carefully controlled conditions to avoid variations in opacity of the coatings.
• the third type of film-that containing the microscopic Voids is widely used, but careful balancing of ingredients is required to produce a film which can be marked at available temperatures but at the same time is not unduly sensitive to pressure. All of these prior types ofcoatings must be applied to a colored base, which is generally paper carrying a dark pigmented coating. In addition, volatile organic solvents are necessarily employed in the production of all three types.
• thermo-sensitive, image-recording copy element comprising a support of low heat conductivity having an outerrstratum containing as the essential heat-sensitive components (1) a 5-hydroxy-3-pyrrolin-2-one having a negative substituent in the 3-position and the general formula:
• R is a member selected from the group consisting of hydrogen, monovalent hydrocarbon radicals of not more than 10 carbon atoms, amino and dialkylamino of 1-2 carbon atoms, the radicals R when separate are each selected from the group consisting of hydrogen, alkyl of 1-10 carbons, cycloalkyl of 4-6 carbons, aryl of 6-10 carbons and aralkyl of 7-10 carbons and when linked together constitute a single divalent hydrocarbon radical which forms with the 4- and 5-carbon atoms of the pyrrolinone ring a carbocyclic radical of 5-7 ring atoms, said substituted pyrrolinones being further characterized in that when substituted with the members recited, not more than one of the 4- and S-carbons have an aromatic substituent and (2) from 0.01 to 1.0 mole per mole of
• metal salt is a cupric salt of an organic carboxylic acid of not more than 4- carbon atoms.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• General Physics & Mathematics (AREA)
• Heat Sensitive Colour Forming Recording (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Color Printing (AREA)

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Citations (5)

• 0
  • NL NL249149D patent/NL249149A/xx unknown
  • BE BE588328D patent/BE588328A/xx unknown
• 1959
  • 1959-04-21 US US807761A patent/US3063863A/en not_active Expired - Lifetime
• 1960
  • 1960-02-15 GB GB5318/60A patent/GB905699A/en not_active Expired
• 1962
  • 1962-02-26 DE DEP24511A patent/DE1194878B/de active Pending

Patent Citations (5)

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