DE1200846B - Thermographic copier material and method for making heat-resistant copies hereby - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

B 41m

German class: 15 k-7/05

Number: 1200 846

File number: M 51374 VTb / 15k

Filing date: January 2, 1962

Opening day: September 16, 1965

The invention relates to heat-sensitive copy sheets and methods for their production and their Use.

According to the invention, novel copy sheet structures are proposed which, when heated locally, in the thermographic copying process described below produces a visibly different image form by implementing implementation participants; the implementation participants can participate in a single Layer or in separate layers on a single support or in separate layers on separate, associated carriers exist; These implementation participants include (1) a Salt of a normally solid organic acid and a noble metal and (2) a «-naphthol its aromatic ring substituted by a hydroxyl group predominantly electron donor groups directly bonded are the alkyl, aryl, alkoxy, aryloxy, hydroxy or amino groups can be, or (1) nickel stearate and (2) N, N'-bisfurfuryldithiooxamide, this structure also is distinguished by the fact that an image-generating conversion cannot take place if the conversion participants (2) containing layer moderately exposed to rays in the near ultraviolet region has been.

The invention also relates to methods of making a heat-resistant copy by means of the above described implementable components, in which a copy sheet structure for the purpose of producing a visible image heated sufficiently by converting the components in the image areas and in which the Sub-surface areas of the layer containing the reactant (2) by exposing the sub-surface areas with strong radiation in the near ultraviolet region either before or after imaging Desensitized at the heating stage.

A well known and important method of copying typed letters and from other graphic originals that have different radiation-absorbing image and background surfaces have is known as a thermographic reproduction method. In this procedure the original that is in heat-conductive contact with a heat-sensitive copy sheet with briefly irradiated with a very strong radiation. Due to the preferential absorption of the radiation in the absorbing Image areas a local heating of the copy sheet is caused, with a visible On-the-fly copy of the original is obtained. With this method, however, the subsurface areas of the Copy sheet is sensitive to heat.

Thermographic copier material and
Method of making heat-resistant
Copies herewith

Applicant:

Minnesota Mining and Manufacturing

Company, St. Paul, Minn. (V. St. A.)

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:

Edwin Allen Grant Jr., Maplewood, Minn .;

John Lowell Reitter, St. Paul, Minn. (V. St. A.)

Claimed priority:
V. St. v. America January 3, 1961
(79 990, 79 991)

It has been found that durable thermosensitive copy sheets have a thermosensitive character Layer comprising a salt of a normally solid organic acid with a noble metal and a cyclic organic reducing agent in a physically separate, chemically reactive Arrangement contains, are useful in the above-described thermographic copying process. Silver salts such as silver behenate and reducing agents such as methyl gallate, dihydroxybenzoic acid or 4-methoxy-1-hydroxydihydronaphthalene, in particular appropriate copy sheets. The coated sheet materials are practically colorless. if as in the thermographic copying process or by brief contact with a heated metal rod are briefly locally heated to a transition temperature between about 90 and 150 ° C, they are darkened so that they are permanently visible, with the generated darkened surfaces absorbing radiation differently are. However, the surface areas remain visibly sensitive to heat.

According to the invention is the production of permanent copies with sharply delimited, colored image areas on a visibly heat-insensitive, practically colorless surface on heat-sensitive

509 687/149

Lichen copy sheets allows that a silver salt and an organic reducing agent as image-generating Contain ingredients.

According to the invention it has been found that heat-sensitive copy sheets containing silver behenate or an equivalent noble metal salt and certain substituted a-naphthols as reactive Components of the visible heat-sensitive layer have been made opposite the thermographic imaging conversion by moderate exposure to rays im near ultraviolet area can be made insensitive.

Another known copying method is a previous exposure of a photosensitive Actinic radiation sheet material is required in a pattern that is reproduced by the original is determined with its radiation-permeable base surfaces. The irradiated areas are not made implementable. The unexposed image areas can in some cases can be visualized by heating, however, in order to generate images with a effective color density with another reactant or an activating agent in be treated in liquid or vapor form. In known devices, the composite Forms of copy sheet and transparency passed over a rotating glass cylinder, the contains a mercury vapor lamp. Usually a 600 watt mercury tube lamp is on one Side of the axis of a glass cylinder with a circumference of 30 cm placed, the composite Formation in contact with the outer surface of the rotating cylinder via an arcuate one Exposed away from about 15 cm at a slowest speed of about 2.5 cm in 5 seconds will.

There have also been proposed heat-sensitive copy sheets in which the local, Short-term heating, visible change caused by a reaction between a metal salt and an organic chelating agent. The implementation produces a strongly colored permanent image. However, these copy sheets also remain visibly heat-sensitive after they have been irradiated with actinic light in the above-mentioned copier.

According to the present invention, a heat-sensitive copy sheet having a visibly changing heat-sensitive layer proposed in physically separate and chemically reactive Arrangement contains a metal salt and an organic chelating agent, the thermographic Copying process or when the sheet is briefly heated to a transition temperature between about 90 and 150 ° C with formation of a visibly differing reaction product react with one another, but they upon exposure to actinic light, such as exposing the sheet to a 600 watt mercury vapor tube lamp from a distance of about 13 cm for a period of 30 seconds, can be prevented from such a reaction.

It is known that dithiooxamide in heat-sensitive copier sheets with metal salts such as Nickel stearate, is reactive; however, these implementation participants remain with the exposure Near ultraviolet rays are sensitive to heat. Surprisingly, it is found been that substituted dithiooxamides, such as Ν, Ν'-bis-furfuryldithiooxamide, in copy sheet masses effectively reacted in the same way with nickel stearate at the transition temperatures, wherein but at the same time a complete desensitization of the copy sheet against such a reaction is made possible by a single sending through the ίο above-mentioned device.

The substituted dithiooxamide and the metal salt can be in a thin film of a resinous or polymeric, film-forming binders are intimately dispersed, which then either in the form of a self-supporting film or as a coating on a paper, film or other paper-like type Backing can be used, with a uniform heat-sensitive copy sheet in a single Coating and drying operations can be obtained. The two implementation participants can also be dissolved or dispersed separately in suitable binders and then in the form of separate Coatings are applied to a paper-like base with drying in between or they can be applied to separate pads. At the last one specified Embodiment, a reaction is made possible at the transition temperature at the interface, when the two sheets are brought into contact with their surfaces. The relative Amounts of the two reaction participants are not essential, especially in the case of those the image-generating conversion takes place at an interface, whereby care must be taken, however, that each conversion constituent is present in an amount that is easily visible during the conversion Change leads. As small an amount as possible of the substituted dithiooxamide is expedient used and this material is arranged in such a way that it has the greatest effect of actinic Exposure to radiation.

Various additives are used to make copy sheets with improved appearance Handling properties or other properties useful. Pigments, fillers, Plasticizers, dyes, waxes, resins and other additives can therefore be incorporated.

If one of the reactants in the copy sheet structure is a salt of a normally solid organic acid and a reducible metal, then the organic reducing agents, which are useful in this embodiment of the invention are predominantly naphthols Electron donor groups directly attached to the aromatic substituted by a hydroxyl group Ring are bound. Alkyl, aryl, alkoxy, aryloxy, hydroxy and amino groups are particularly effective. Examples of these compounds include: 4-methoxy-1-naphthol, 4-ethoxy-1-naphthol, 3-hydroxy-l-naphthol, 4-amino-l-naphthol, 2-methyl-4-methoxy-l-naphthol, 4,4'-dimethoxy-1,1'-dihydroxy-2,2'-binaphthyl, 1,1'-dihydroxy-2,2'-binaphthyl and the bis-dihydroxynaphthalene-dimethylmethane condensation product from 1,5-dihydroxynaphthalene and acetone. The condensation product of 2 moles of 1,5-dihydroxynaphthalene and 1 mole Adipoyl chloride is also useful. The compound 2-phenyl-4-methoxy-l-naphthol can also be used as a re-

5 6

reducing agents are used, and that with this typical resin-like or polymeric, film compound and silver behenate as binding agents that generate the reaction part include polystyrene, copier sheets produced by polystyrene are also resistant to n-butyl methacrylate, polyvinyl acetate, ethyl cellulose, visible change when heated, insensitive to polyisobutylene and copolymers made from styrene and when it is with rays in the near ultraviolet 5 isobutylene. The implementation participants are moderately irradiated in the area. preferably together with small amounts of the binder used as an organic reducing agent as a coating on a paper-like carrier, other groups can also be applied, but they can also be contained in a fiber, although the electron donor-like sheet structures are more practical Absence of a group must predominate. In the compounds io binder or in the form of a thin, self-2-acetyl-4-methoxy-l-naphthol and 2-behenoyl-bearing binder film in the absence of a 4-methoxy-l-naphthol ζ. B. has the alkoxy substrate-like carrier used,
do the greater effect; Therefore, if these compounds are used in the same manner as above in fertilizing, the dithiooxyamide-containing copy sheets are obtained, which, however, have been named 15, for the purpose of improving the substantially higher conversion temperatures and appearance, handling properties and of a much longer exposure time with rays with different properties can be used. The use of near ultraviolet to produce the incorporation of various toning agents is required to produce desirable results. . especially in compositions containing silver soaps. Of the compounds given above, 30 provide moderate, because this improves the color and density of the er-4-methoxy-l-naphthol and compounds such as retained image.
2-methyl-4-methoxy-l-naphthol, which contain further elec- The composite structure from copier sheet electron donating, substituting groups, and original is first after known thermo-heat sensitive copier sheets, which are the most effective graphic copying process with a strong, at combination of conversion ability easy to- 25 infrared-rich radiation briefly irradiated. The conversion temperatures customary in this case and the image-bearing copy sheet obtained will then have the greatest sensitivity to the action of moderate rays of a wavelength in the near ultraviolet-ultraviolet rays; these compounds area, such as with rays from a mercury vapor lamp, are therefore irradiated in the proposed copy sheets. At this time, the heat sensitive is preferably used. The reducible metal ions are preferentially any visible change in the appearance of the wise in the form of silver behenate or of silver background or the image areas is caused by stearate, but other salts can also be obtained by another method Copies of a normally solid organic acid and can be made by first using the copy sheet of noble metal. The water 35 through a transparency, z. B. by a tape-insoluble salts of higher fatty acids or a carbon copy of a typewriter written because of its insensitivity to moisture enclosed document on a thin, semi-preferably used. visible paper exposed to near ultraviolet. B. on a heated roller-like or polymeric film-forming binder or plate or in an oven, is heated,
are intimately dispersed, which is then either in the form of the following examples serve to further create a self-supporting film or as a coating to clarify the invention. The proportions are, paper, film or other paper-like, unless otherwise specified, parts by weight.
Pad can be used, with a unit- 45

Lich heat-sensitive copy sheet in one example 1

A number of coating and drying operations are obtained from mixture A

can be. The two implementation participants nickel stearate 6 6

Silica powder can also be used separately in suitable binders 23

dissolves or disperses and then in the form of 50 polyvinyl acetate resin ...'.'........ 4.6

separated coatings on a paper-like base acetone 86 5

be applied, with drying in between

or you can also use mixture B on separate documents

be applied. In the case of the last-mentioned N, N'-bis-furfuryldithiooxamide .. 0.1

Embodiment is 5.0 at the conversion temperature ethyl cellulose

temperature at the interface enables a reaction, acetone 94.9

when doing the two sheets with their surfaces

be brought into contact. The Relative Amounts Mixture A will deteriorate over a long period of time Both implementation participants are produced especially when grinding in a ball mill, then in one not essential to the structures in which the image-thin, even layer is created on tracing paper Implementation takes place at an interface, wear and dry. The mixture B is through however, care must be taken to ensure that any mixing of the constituents until dissolution is achieved is present in a crowd. The solution is then in the form of a thin, which in the implementation becomes an easily visible even coating on the first produced change leads. A coating that is as small as possible is expediently applied, whereupon the sheet is again slightly Amount of α-naphthol is used and is being dried. It becomes a heat sensitive this material arranged so that it will get the largest copy sheet with a neutral color. At the Exposure to actinic radiation. local heating, such as by brief exposure

7 8

stirring the leaf with a small amount of phthalazinone heated to 150 ° C (more precisely than Test rod, a strong darkening (2 H) -phthalazinone is to be designated) saturated causes. has been. The mixture turns to a white

A portion of the copy sheet is placed under a paper support with an overcoat blade in the case of an open graphic Original, which has been applied by writing on a width of 0.005 cm and then produced on thin paper, placed and dried at temperature. The sheet obtained has on the structure after a thermographic a white color, which on brief contact with a Copying process is irradiated. A metal rod heated to 120 ° C is converted into a deep blue sharpness and clear reproduction of the written black.

Sign received. The copy is then made from an io The sheet is then combined with a printed original Distance of about 13 cm brought into contact with a strong jet, whereupon the structure with the treatment in the near ultraviolet region for 30 seconds with rays from a conventional filament lamp irradiated with a mercury vapor lamp. The dark thermographic copying process is strong for a short time Image areas remain unchanged. The underground is irradiated. The image areas that the printed areas are no longer darkened if they correspond to 15 areas of the original, are thereby briefly colored blue-black in contact with the heated test rod; the underground areas remain to be brought. white and are still sensitive to heat.

Another part of the copy sheet is under The copy is then subjected to a long-term irradiation

a printed see-through image exposed by exposure to an 8-watt ultraviolet lamp, write a thin, semi-transparent paper 20, finding that the ground surfaces has been produced, whereupon they are no longer visibly sensitive to heat and white The composite structures remain irradiated with near ultraviolet when tested with a heated metal. The structure that is brought into contact with the see-through rod or a thermal image aligned copy sheet is then subjected to graphic copying processes, as in a thermographic copying process 25 The previously darkened image areas remain unshortened irradiated. The copy obtained has sharply changed.

bordered, dark image areas on a neutral The dark image areas absorb infrared rays

Underground and is against further heating on lung, while the non-darkened underground -150 ° C resistant. surfaces both before and after the desensitivity

The image areas can also be easily developed without absorbing a substantial amount of infrared rays, in that the transparency before irradiation does not absorb; the stabilized copies, which have been replaced by a sheet of a radiation-absorbing black paper this and on the absorbing black paper in the following examples or by written heat-sensitive copy sheets herd the copy sheet with a heated metal plate or made, can therefore be made in the manufacture of a roller in contact or in an oven to 35 ment of further copies after thermographic 150 ° C is heated. Reproduction methods as graphic originals if Ν, Ν'-bis-furfuryldithiooxamide and nickel are used,
stearate used as reactive materials Example 3

a purple image area is obtained.

Nickel stearate gives with N-N'-bis-carboxyamyldithio- 40 silver behenate is beoxamid according to the example 2 a pale red picture. Other nickel salts, produced as described, but with Nickel behenate, give similar results. Cobalt equimolar amounts of silver nitrate and sodium and copper salts are also useful. Other behenat can also be used. 10 g of this salt will be obvious embodiments can be used by ball milling in a lozenge. 45 solution of 10 g of n-butyl methacrylate polymer in 90 g Example 2 Heptane dispersed, whereupon the dispersion is applied to tracing paper with an opening of 0.076 mm An equimolar mixture of silver behenate and will. A Behenic acid is applied by reacting 1 mol of silver solution made from 0.05 g of 4-methoxynitrate with 2 moles of sodium behenate, which has been prepared from commercial 50 1-naphthol, a trace of phthalazinone and 1 g of conventional behenic acid, in 9 g of aqueous resin (n-butyl methacrylate polymer) medium and under weakly acidic conditions acetone, whereupon the leaf again dried manufactured. The resulting water-insoluble net is. The sheet supplies at thermographic Deposition is filtered off, washed and getrock- reproduction method very good reproductions of net, whereby a fine powder is obtained. The powder 55 graphic originals. By exposing the so sintered at about 135 ° C and melts copy held at about 175 ° C with a high pressure mercury a liquid. Silver behenate and behenic acid, arc lamp from a distance of about 15 cm which are made from the same sodium behenate separately and for a period of about 2 minutes are the have been made, melt at around 220 and / or subsurface areas are insensitive to heat Made at 70 ° C. 60.

A dispersion of 1.35 g of the silver soap example 4

mixture in a solution of 0.9 g of polystyrene resin

with a viscosity of 15 to 25 cP in 6.75 g of thin paper is with a dispersion of

2-Butanone as a volatile, liquid carrier turns silver behenate into a solution of n-butyl meth Long-term grinding in a spherical 65 acrylate polymer coated in heptane, whereupon the mill made. Immediately before coating, coating is dried and then with a solution of 0.2 g of 4-methoxy-1-naphthol and a further 0.05 g of 4-methoxy-1-naphthol and 0.25 g of phthal-11.0 g of 2-butanone were added, which was previously coated with an azinone in 18 ecm of methanol. the

Solution is applied in a very small amount with the help of nip rollers, whereupon the sheet dried and a heat-sensitive copying sheet is obtained, which when heated to the transition temperature becomes black, but undergoes such a color change by heat by irradiating with near ultraviolet for one minute the conditions specified in Example 3 is made insensitive.

10

Example 5

Paper is made with a mixture of 10 g of silver behenate, 5 g of phthalazinone as a toning agent, 3 g of a copolymer of isobutylene and styrene and 82 g of heptane with a coating opening of 0.076 mm coated and then dried. Solutions of 0.01 g of the reducing agent in 6 ecm of a solution of 7 parts of ethyl cellulose binder in a mixture of 63 parts of methanol and 7 parts of water are then applied to separate portions of the coated paper having an opening of 0.076 mm. The dried leaves obtained are then through a mask or stencil with a High pressure mercury arc lamp from a distance of about 20 cm for about 3 minutes irradiated with ultraviolet light and then brought into contact with black paper and with light rich in infrared, e.g. B. obtained from a thermographic copier can be irradiated for a short time. The black paper absorbs the radiation and generates at the same time an even heating. The following compounds are considered effective, photosensitive, reducing compounds have been used, only those covered in the method described Areas can be effectively darkened.

4-methoxy-1-naphthol,

2-methyl-4-methoxy-1-naphthol,

4-ethoxy-l-naphthol, 4,4'-dimethoxy-l, l'-dihydroxy-2,2'-binaphthyl, 1,4-dihydroxynaphthalene,

1,3-dihydroxynaphthalene,

Condensation product of 1,5-dihydroxynaph-

thalin and acetone,
4-amino-1-naphthol.

Other coatings can optionally be applied, such as coloring or opacifying Coatings, surface protective coatings or coatings for other purposes. In one embodiment if the carrier sheet used is transparent, the heat-sensitive layer consists of a single coating that has all of the required actionable materials in one see-through Contains binder, and there is another coating of a strongly pigmented binder on the heat-sensitive coating, which serves as both a protective layer and an effective one Contrast with the dark areas of the image is provided by the heat-sensitive layer the reproduction process. In such an embodiment, of course, must Carrier sheet be transparent. In embodiments where the visibly heat sensitive Layer consists of two coatings, the use of a transparent base enables the application of the photosensitive reducing agent as

45 first coat, on which the silver salt and the other ingredients and optionally an opaque surface coating are applied; such a sheet is desensitized by irradiating it with ultraviolet light through the transparent carrier sheet.

Claims (8)

Patent claims: 1. Thermographic copying material on which when heated in a thermographic Copying process a visibly different image is generated by converting implementation participants in a single Layer or in separate layers on a single support or in separate layers separate, associated carriers are present, characterized in that the Reaction participants from (1) a salt of a normally solid organic acid with a noble metal and (2) an α-naphthol on which substituted by a hydroxyl group aromatic ring predominantly electron donor groups are directly bound, the alkyl, aryl, Can be alkoxy, aryloxy, hydroxy or amino groups, or from (1) nickel stearate and (2) Ν, Ν'-bis-furfuryldithiooxamide consist, and in that the structure is further characterized in that there is no imaging conversion more can take place if the layer containing the reactant (2) is exposed to rays is moderately irradiated in the near ultraviolet area. 2. Thermographic copying material according to claim 1, characterized in that it is in physically separated and chemically convertible arrangement nickel stearate and Ν, Ν'-bisfurfuryldithiooxamide contains. 3. Thermographic copying material according to claim 1, characterized in that it is in essentially from a paper-like base and a layer from one of the implementation participants (2) exists. 4. Thermographic copying material according to claim 1, characterized in that the Reactant (1) is a silver salt of a normally solid organic acid. 5. Thermographic copying material according to claim 1 or 4, characterized in that that the reactant (1) silver behenate and the reactant (2) 4-methoxy-1-naphthol is. 6. Method for producing a heat-resistant copy with a capping material according to one of the preceding claims, characterized in that the copy sheet structure in the Image areas for the purpose of generating a visible image by converting the implementation participants sufficiently heated and that then the subsurface surfaces of the layer, which the reactants (2) contains, by exposing the background surface with a strong radiation in the near Ultraviolet area desensitized either before or after the imaging heating step will. 7. The method according to claim 6, characterized in that for the purpose of generating the image a graphic original with infrared-absorbing image areas in thermally conductive contact with the copy sheet with rays rich in infrared 509 687/149 is briefly strongly irradiated and that then subsequently the sub-surface areas by exposure of the copy sheet can be desensitized with strong radiation in the near ultraviolet region. 8. The method according to claim 6, characterized in that the copy sheet structure that the Implementation participant (2) contains, through a graphic original, that for near ultraviolet is differently permeable, irradiated with a strong radiation in the near ultraviolet area being the areas on the copy sheet that are the more transparent areas of the graphic Originals are desensitized to the conversion of heat, and then that Copy sheet for the purpose of producing a visible image in the areas that are less transparent Areas of the graphic original correspond to the conversion triggered by heat is heated sufficiently between the reaction participants (1) and (2).