US3523791A - Process of thermographic copying - Google Patents

Process of thermographic copying Download PDF

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Publication number
US3523791A
US3523791A US559522A US3523791DA US3523791A US 3523791 A US3523791 A US 3523791A US 559522 A US559522 A US 559522A US 3523791D A US3523791D A US 3523791DA US 3523791 A US3523791 A US 3523791A
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Prior art keywords
gelatin
layer
heat
recording
original
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US559522A
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English (en)
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Marcel Nicolas Vrancken
Alexander Riebel
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Agfa Gevaert NV
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Agfa Gevaert NV
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/025—Duplicating or marking methods; Sheet materials for use therein by transferring ink from the master sheet
    • B41M5/06—Duplicating or marking methods; Sheet materials for use therein by transferring ink from the master sheet using master sheets coated with jelly-like materials, e.g. gelatin

Definitions

  • the present invention relates to a method for recording and reproducing information by means of image-Wise reflected electromagnetic radiation.
  • a recording material which contains a recording layer mainly consisting of gelatin and containing in heat-conducting relationship therewith substances that absorb visible light and convert it into heat, is reflectographically exposed to an original as defined hereinafter, the exposure being of short duration and of such high intensity that an image or record is formed as an increase in the rate of swelling and dissolving of the gelatin in water.
  • the original is one containing image areas on an imagebackground that reflect(s) visible light or is a transparency or stencil that has electromagnetic radiation absorbing areas and that is held during the exposure with its backside in contact or in proximity of a material reflecting visible light.
  • Originals wherein both image areas and background reflect Visible light but to sufliciently different extents for obtaining a practically useful image differentiation are not excluded.
  • gelatin layer For reproduction purposes use is made of the imagewise differentiation in swelling degree of the layer mainly consisting of gelatin, called hereinafter the gelatin layer.
  • the gelatin layer which after exposure is moistened with water or an aqueous liquid composition, shows a gelatin relief image, which may be used for producing a printing master.
  • a gelatin stratum of the swollen areas corresponding with the heat pattern can be transferred to a receiving sheet. If the gelatin is hardened to a certain degree only moisture absorbed in the swollen portions is transferred.
  • the heat applied in the gelatin-containing recording layer may only result from the light converted into heat in said substances and that no heat absorbed by the image markings of the original may be transferred to the said layer in such an amount that a differentiation in solubility and swellability in water is obtained.
  • the gelatin-containing recording layer may stand in contact with the lightabsorbing markings of the original during that exposure.
  • the said markings are thus in some degree in heat-conducting relationship with the gelatin layer, they do not elfectively heat the gelatin. So, it is apparent that the recording method is not dependent in any way on the extent of contact between the original to be recorded and the gelatin-containing layer during exposure.
  • a poorly heat-conductive material e.g. a paper support or resin layer or support is arranged.
  • said layer or support of course has to be transparent for the copying light.
  • An increase in temperature of the gelatin of between 50 and 200 C. causes a substantial increase in the tendency of the gelatin to swell in water.
  • the gelatin exists in gel state whereas by heating the gelatin structure is changed in a structure similar to that of a sol-dried gelatin, i.e. a gelatin dried at a temperature higher than 35 -40 C.
  • the differential swelling tendency of the gelatin layer can be observed directly when moistening the layer with water.
  • the swelling tendency of the gelatin varies with the hardening degree. After the exposure a substantially unhardened gelatin layer will have regions which can be washed away completely by water at 25 C. and will provide transfer images of gelatin. After a similar exposure a layer of gelatin hardened in known way will show the increased swelling tendency only as a difference in the rate of swelling between the areas heated by the reflected light that is absorbed and those not, or negligibly, struck by reflected light. This may be illustrated by immersing the gelatin layer in an aqueous solution of a dye for only a few seconds, which results in a preferential absorption of the dye solution into the heated portions, thus producing a dye image.
  • hectographic printing masters can be formed by using a gelatin relief image produced as described above.
  • a heat-sensitive gelatin layer which contains a water-insoluble or water-insolubilized hectographic dye or a colour reactant for forming a hectographic dye. Therefore, after the 'reflectographic exposure, the gelatin portions which are heated by the heat resulting from the reflected light that is absorbed are completely washed away by water having a temperature of 20 to 30 C. thus leaving a laterally reversed gelatin reliefimage.
  • the material containing said image can be used as hectographic printing master.
  • the material containing a laterally reversed gelatin relief which is obtained after exposure and washing away the image-wise heated gelatin portions, is pressed with the gelatin relief against a hectographic carbon paper, e.g. as is used in the process according to the Canadian patent specification 666,600 and then after a few seconds peeled apart therefrom whereby a stratum of the dyestuff layer of the carbon paper is transferred to the laterally reversed gelatin relief image obtained.
  • the material containing the transferred stratum of said dyestufl layer can be used as hectographic master.
  • a hectographic master for producing negative prints can be formed by transfer of the swollen gelatin portions to a receiving sheet.
  • the said gelatin portions can be dyed before or after the transfer.
  • the said transfer can be carried out by contacting under pressure a receiving sheet with the gelatin relief image, preferably between two rollers-at least one of which is preferably heated to a temperature between 30 and 50 C., and peeling apart both materials after emerging from the rollers.
  • a gelatin stratum of swollen gelatin or a gelatin stratum that remains after washing out the swollen portions can lac-transferred to a hydrophobic or hydrophilic lithographic support.
  • hydrophilic support may be used for instance a grained zinc, or aluminum or a casein-coated paper. In case a hydrophilic support is used the transferred gelatin has to be made hydrophobic.
  • planographic printing master obtained can be used in conventional lithographic printing processes wherein use is made of a'lipophilicink and a damping system or aluminium sulphate, chrome alum, potash alum, formal- V 3 in the planographic printing process described in the Belgian patent specification 676,898 filed Feb. 23, 1966 by Gevaert-Agfa N.V. wherein use is made of a hydrophilic ink.
  • the swellable gelatin can be applied in or over the screen openings of a support suited for stencil preparation.
  • a support suited for stencil preparation.
  • Japan paper Yoshino paper
  • nylon fabrics with a size of mesh of 0.2 to 0.08 mm. and woven bronze wire are specially suitable.
  • the stencil can be prepared by washing out the image-wise heated gelatin portions. It is, however, also possible to prepare a stencil by image-wise transferring a stratum of moist and swollen gelatin to a screening material containing no coating; so image-wise filling up the screen-openings through which the stencil ink on printing may not penetrate.
  • the transfer'red gelatin may be hardened to improve the mechanical strength of the stencil.
  • Various types of gelatin can be used for preparing the heat-sensitive recording material; so it has been found that gelatins with low Bloom gel strength value as well as gelatins with Bloom gel strength value above 200 are suitable for obtaining a practically useful image-differentiation as will be illustrated further on in the examples.
  • Suitable gelating layers for application in the present invention are described in UK. patent specification 985,933 filed Apr. 14, 1961 by Kodak.
  • the gelatin that is useful in the recording and reproduction method as described above includes derivatives of gelatin such as those described in Belgian patent specification 484,324 filed Aug. 26, 1948 by Kodak, Belgian patent specification 606,122 filed July 14, 1961 by Gevaert Photo-Producten N.V. and in Belgian patent specification 609,566 filed Sept. 27, 1961 by Gevaert Photo-Producten N.V.
  • gelatin relief transfer image When from one matrix more than one gelatin relief transfer image has to be formed it is preferred to use a substantially unhardened gelatin and to carry out the transfer in the presence of a gelatin tanning agent e.'g.
  • dehyde, chromium chloride, glyoxal and tannic acid which hardening agents are generally incorporated in the aqueous moistening bath. This enables a large number of transfer copies to be obtained.
  • a gelatin layer is used that has been hardened with a metal salt e.g. aluminium sulphate which is removed afterwards whereby an runhardened gelatin is left.
  • the gelatin - is preferably unhardened by a treatment with a complexing agent for the meal ions of the hardener.
  • the complexing taining said" substances that absorb electromagnetic radiation and transform it into heat to a transparent support which practically does not conduct heat e.g. a cellulose triacet'ate support.
  • the optical density of the gelatin layer in respect of the used copying light is preferably between 0.3 and 0.8.. In otherwords, preferably at least 20% and at most 80% of the copying light is transmitted through the recording material and-impinges onto the image-wise reflecting original.
  • the gelatin layer is preferably mainly composed of gelatin” (it preferably consists of more than 80% by weigh't'of gelatin) but may contain to a certain degree substances in dissolved and/or dispersed state, with the proviso, however, that these substances do not or only slightly adversely aifect the desired swelling rate. So,
  • the gelatin layer may contain e.g. dyes, catalysts or reaction components for the formation of dyes, protective colloids for the applied dispersed substances, reducing agents, developing substances for silver halide, finely divided metal that can be etched, developing nuclei for complexed silver halide, light-sensitive substances, plasticizing agents, hygroscopic compounds e.g. glycerol, 1,5-hexanediol and magnesium chloride, and curing agents in latent form.
  • concentration of these ingredients in the thermo-sensitive layer or other layer or sheet forming part of the recording material may not be such that the heat-sensitive material becomes too opaque for refiectographic exposure.
  • substances which absorb visible light and infra-red light and convert it into heat of conduction are preferably used: finely divided carbon black, graphite, prussian blue, oxides, sulphides or carbonates of heavy metals, particularly of those heavy metals having an atomic weight between 45 and 210, such as manganese or lead sulphide or these heavy metals themselves in finely divided state such as silver, bismuth, lead, iron, cobalt and nickel.
  • the amount of pigment incorporated into in the recording layer is preferably such that an optical density of the layer of 0.20 to 0.80 is obtained.
  • the gelatin layer is, during the exposure, uniformly in heat-conductive relationship with coloured substances which absorb light of a determined part of the visible spectrum and convert it into heat.
  • a gelatin layer spectrally sensitized in this way can be used for recording coloured originals in terms of differences in solubility and in swelling tendency in water.
  • mixtures of said coloured substances can be used too, so that light of the whole visiblespectrum is absorbed. Further the said substances have not to absorb in the range of the visible spectrum alone, they may absorb in the infra-red region although for a good recording of red coloured image-markings the latter absorption is preferably as low as possible.
  • the coloured substances or mixture of said substances when used for optical sensitization of the gelatin layer preferably absorb light corresponding to at least one of the primary colours (red, green, blue) or subtractive solved state; when they are used in dispersed form they are preferably applied with a grain size lower than 0.1
  • the present invention when using optically sensitized gelatin layers, it is possbile to produce printing masters suitable for colour printing and forproducing multicolour copies of colour originals.
  • three materials are usedv that contain a heat-sensitive gelatin layer comprising a substance which is heated on absorbing red, green and blue light respectively, i.e. a gelatin layer containing a cyan dye, a magenta dye and a yellow dye respectively.
  • Said dyes may be dyes suitable for hectographic printing.
  • the heat produced in the heat-sensitive gelatin layer containing the magenta dye said layer is made more swellable and water-dissolvable in the areas corresponding to the green areas of the original to which it was exposed.
  • Multicolour prints can be produced by using the three exposed materials to prepare three separate masters which are used to print in register.
  • three separate gelatin layers can be used which are sensitized for blue, green and red respectively by a blue, green and red dye or pigment that is uniformly distributed therein. By washing away the selectively heated gelatin portions copies of the image markings in the primary colours are obtained.
  • the effectiveness of the recording with visible light substantially depends on the intensity of the radiant energy.
  • a gelatin recording layer that does not provide a sufiicient differentation in swelling tendency with a particular source of electromagnetic radiation energy may be fully effective if the energy level is substantially increased.
  • Lamp structures and exposure systems producing electromagnetic radiation at least 70% of which consists of visible light (in other words containing only small amounts of U.V. light and infra-red light) and which are capable of providing high-intensity radiation in a very small lapse of time are preferably used.
  • the heat-sensitive material may be reflectographically scanned with an image-wise modulated light-spot of high intensity, e.g. a laser beam, or may be progressively exposed through a slit wherein, e.g., copying light of a continuously emitting tube-like radiation source is focused.
  • the gelatin layer is in contact with light-absorbing markings of the original during the exposure. Although the said markings are thus in some degree in heat-conductive relationship with the gelatin layer they do not or do not effectively heat the gelatin.
  • a flash exposure is used, and during this exposure the only effective heating of the gelatin which occurs is due to the heating of the light-absorbing substance which is distributed in the gelatin layer. itself.
  • EXAMPLE 1 A poly(ethylene terephthalate) support of 0.1 mm. thickness provided with a subbing layer for gelatin is coated with the following composition pro rata of 50 g./sq. m.:
  • the recording material After exposure the recording material is dipped in water of 20 C. and gently rubbed. The areas corresponding to the white background of the original are washed away, whereas the areas corresponding to the absorbing letter marks 22 do not dissolve.
  • the gelatin relief obtained is pressed a'gainst the dyestutf layer of a hectographic carbon carrying no hydrophobic surface layer.
  • both layers are separated.
  • a stratum of the dyestutf layer is transferred to the gelatin relief image, so that a dyestulf containing laterally reversed relief image of the original is obtained.
  • This material can then be utilised as a spirit duplicating master.
  • EXAMPLE 2 A cellulose triacetate support of 0.12 mm. thickness provided with a subbing layer for gelatin is coated with the following composition pro rata of 30 g./sq.
  • EXAMPLE 3 A poly(ethylene terephthalate) support of 0.1 mm. thickness provided with a subbing layer for gelatin is coated with the following composition pro rata of 70 g. per sq. m.: G aqueous gelatin solution (the gelatin has a Bloom gel strength value of 140) 450 10% aqueous saponin solution 3% aqueous solution of the sodium salt of the condensation product of oleic acid and methyltaurine 15 Pigment griin B Pigmosol (C.I. 10.006) 10 Permanent Violett R.L. Colanyl Teig (C.I. 51.300)
  • EXAMPLE 4 A poly(ethylene terephthalate) support of 0.1 mm. thickness provided with a subbing layer for gelatin is coated with the following solution pro rata of g. per
  • both layers are separated.
  • a stratum of the dyestufl layer is transferred to the gelatin relief so that a dyestutf containing laterally reversed image of the original is obtained.
  • This material can then be utilised as a spirit duplicating master.
  • EXAMPLE A poly(ethylene terephthalate) support of 0.14 mm. thickness provided with a subbing layer for gelatin is coated with the following composition pro rata of 50 g./sq./m.:
  • G 10% aqueous solution of gelation having a Bloom gel strength value of 240 450 10% aqueous saponin solution 10% aqueous dispersion of colloidal silver 2 0
  • the layer is dried at C.
  • the heat-sensitive copying material 32 comprising a poly(ethylene terephthalate) support 35, a gelatin subbing layer 34 and a heat-sensitive layer 33 is reflectographically exposed with a flash-lamp 27 to an opaque original 36 as diagrammatically illustrated in the accompanying FIG. 3.
  • the material After exposure the material is slightly wetted with water and then with its heat-sensitive layer pressed against a receiving paper. Material and receiving paper are led between two pressure rollers at a travelling speed of about 10 cm./sec., and peeled apart. A thin stratum. of the heatsensitive layer is transferred image-wise to the receiving paper. A hectographic carbon with its dyestuif layer carrying no hydrophobic surface layer is pressed against the receiving paper. After a contact time of about 1 min. both layers are separated. A dyestuff-containing laterally reversed image of the original is obtained on the receiving paper which can be used as a spirit duplicating master.
  • a method of recording information comprising the steps of providing a recording material including a recording layer, which consists of at least about 80% by weight of gelatin and contains homogeneously distributed therein a finely divided material that absorbs visible light and converts absorbed light into heat, said material being present in such an amount that at least 20% and at most 80% of the visible light to which the original is exposed is transmitted; reflectographically exposing the recording layer while in direct contact with an original having visible light-absorbing markings on a visible light-reflecting background for a time not longer than 10 seconds, said exposure being of such an intensity as to heat portions of said recording layer corresponding to said background to the extent that the swelling rate and the rate of dissolution in water of the gelatin are increased but not of such intensity as to heat portions of said recording layer corresponding to said light-absorbing markings to the extent that the swelling rate and the rate of dissolution in water of the gelatin are increased, and developing the image formed on the recording layer by swelling or dissolving the heated portions of the gelatin.
  • I12 A method for recording information according to claim 1, wherein said substances absorb light of a determined part of the visible spectrum and transform it into heat.

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  • Thermal Transfer Or Thermal Recording In General (AREA)
US559522A 1965-06-22 1966-06-22 Process of thermographic copying Expired - Lifetime US3523791A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB50442/65A GB1154902A (en) 1965-06-22 1965-06-22 Improvements in or relating to a process of Thermographic Copying
GB2646765 1965-06-22
AU63726/65A AU406187B2 (en) 1965-06-22 1965-09-07 Smash-resistant offset printing blanket

Publications (1)

Publication Number Publication Date
US3523791A true US3523791A (en) 1970-08-11

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US559522A Expired - Lifetime US3523791A (en) 1965-06-22 1966-06-22 Process of thermographic copying

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US (1) US3523791A (de)
AT (1) AT276937B (de)
AU (1) AU406187B2 (de)
BE (1) BE682767A (de)
CH (1) CH470268A (de)
DE (1) DE1571818A1 (de)
GB (1) GB1154902A (de)
NL (1) NL6608504A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811773A (en) * 1965-11-26 1974-05-21 Agfa Gevaert Nv Thermographic copying
US4017312A (en) * 1974-12-23 1977-04-12 Mitsubishi Plastics Industries, Limited Method of manufacturing an article carrying a relief image receptor material comprising exposure and heating steps
US4113487A (en) * 1975-10-31 1978-09-12 Toppan Printing Co., Ltd. Method for manufacture of expanded articles having an embossed surface
US4268615A (en) * 1979-05-23 1981-05-19 Matsumoto Yushi-Seiyaku Co., Ltd. Method for producing relief
US5035977A (en) * 1989-06-16 1991-07-30 Eastman Kodak Company Infrared absorbing oxonol dyes for dye-donor element used in laser-induced thermal dye transfer

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3121162A (en) * 1960-04-16 1964-02-11 Eastman Kodak Co Thermographic colloid transfer process
US3298833A (en) * 1960-12-30 1967-01-17 Gen Electric Method for storing information

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3121162A (en) * 1960-04-16 1964-02-11 Eastman Kodak Co Thermographic colloid transfer process
US3298833A (en) * 1960-12-30 1967-01-17 Gen Electric Method for storing information

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3811773A (en) * 1965-11-26 1974-05-21 Agfa Gevaert Nv Thermographic copying
US4017312A (en) * 1974-12-23 1977-04-12 Mitsubishi Plastics Industries, Limited Method of manufacturing an article carrying a relief image receptor material comprising exposure and heating steps
US4113487A (en) * 1975-10-31 1978-09-12 Toppan Printing Co., Ltd. Method for manufacture of expanded articles having an embossed surface
US4268615A (en) * 1979-05-23 1981-05-19 Matsumoto Yushi-Seiyaku Co., Ltd. Method for producing relief
US5035977A (en) * 1989-06-16 1991-07-30 Eastman Kodak Company Infrared absorbing oxonol dyes for dye-donor element used in laser-induced thermal dye transfer

Also Published As

Publication number Publication date
CH470268A (de) 1969-03-31
AU6372665A (en) 1967-03-09
AU406187B2 (en) 1970-09-23
GB1154902A (en) 1969-06-11
AT276937B (de) 1969-12-10
DE1571818A1 (de) 1971-01-14
NL6608504A (de) 1966-11-25
BE682767A (de) 1966-12-20

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