US3421894A - Recording process utilizing 6'-nitro-1,3,3 - trimethyl-benzoindolinospiropyran dispersed in heat-meltable wax - Google Patents

Description

Jan. 14, 1969 BAUM 3,421,894

RECORDING PROCESS UTILIZING e--NITRo-1.5.5,-TRINETHYI.-

BENZOINDOLINOSPIROPYRAN DI-SPERSED IN HEAT-MELTABLE WAX Filed Jan. 13, 1966 Sheet of 2 SOLID Low nsurmc POINT WAX COATING FIG wr'm DISPERSION or PARTICLES OF CRYSTALLIZED Puorocummc COMPOUND or n5. 4 sowsm IN ms fax WHEN mzurzo POLYMERIC FHM COATING WITH INCLUSIONS OF SOLID LOW MELTING POlNT WAX EACH 2 LNCUJSION HAVING DISPERSED THERElN PARTICLES 0F CRYSTALLINE PHOTOCHRDMLC DYE COMPOUND OF FIG. 4

PAPER-LIKE- F Q6 3 SENSITIZE comm swam 01- ncs. 1 on 2 mm HEAT SUFFICIENT T0 MELT wAx AND DISSOLVE THE ms 0 MAY BE 40 c. 80 c. comamzo m REGARD TO TIME mum: ms Is IN SOLUTION EXPOSE com- INC IO ULTRA-VIOLET usu'r 1N AREAS WHERE comm) IMAGE Is To BE MADE mum: nvs sum, Is IN soLu'r oN I I :xposz ANY cowxzo AREA 1': IS OPT'ONAL STEP DESIRED '10 ERASE TO GREEN-YELLOW LE J 51x SHEET BY HEATING AGAIN 1'0 WAX- MELTING TEMPERATURE AND ALww sass: TO 0001. m ROOM maPEmmRa INVENTOR HENRY H. BAUM HIS ATTORNEYS Jan. 14, 1969 H, BAUM 3,421,894

RECORDING PROCESS UTILIZING 6-NITRO-1,5.5.-TRIMETHYL- BENZOINDOLINOSPIROPYRAN DISPERSED IN HEAT-MELTABLE WAX Filed Jan. 13, 1966 Sheet 8 of 2 mvEmoR HENRY H. BAUM HIS ATTORNEYS United States Patent Ofifice 3,421,894 Patented Jan. 14, 1969 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for using a record sheet sensitized by a layer of heat-meltable wax having dispersed in it the compound 6-nitro-1,3,3,-trimethylbenzoindolinospiropyran, by first heating the layer to fuse it, then subjecting the heated layer to an ultraviolet light pattern, representing the record, to form a precursor image, which image finally is fixed by a further heating step to form a fixed copy of distinctive color in the layer. The application claims the method of using the sheet.

This invention relates to a printing and copying sheet, a system employing the sheet, and its use; and more particularly pertains to such a system employing as a chromogenic material the compound 6-nitro-1,3,3-trimethv benzoindolinospiropyran, which has the structure and which compound is used dispersed in a wax material taken from the group of waxes consisting of mineral wax, vegetable wax, synthetic fatty ester wax, and animal wax, such wax being characterized by having a solid state in the range of 20 degrees centigrade :20 degrees centigrade and a liquid state above 40 degrees centigrade, preferably in a layer, and is present there at various stages of its selective use either as a dispersed crystalline state (colorless), a heat-induced solute state (colorless), an ultravioletdight-induced activated state (magenta), a fixed state on heating (blue or colorless, according to whether or not it has experienced incident ultraviolet light while in heat-induced solute state), and a colorless state to which the activated state reverts on long standing (maximum a few hours) or to which it more immediately reverts upon exposure to green light or light of wave lengths longer than green.

The behavior of the system cannot be fully explained theoretically, but the utility of the system can be explained and such utility will be exemplified in many ways, as will be shown in a preferred and other embodiments specified with reference to the drawings, in which:

FIG. 1 represents a paper substrate coated with a layer of low-melting-point 40 degrees centigrade) wax solid at room temperature (10 degrees centigrade to 35 degrees centigrade) in which are originally dispersed fine crystalline particles of the specified chromogenic material, said crystals pervading the wax layer in amount and distribution so as to be individually detectable visually when colored.

FIG. 2 shows a substrate of paper coated with a polymeric material film in which are dispersed wax particles of the composition of the wax layer of FIG. 1, the wax particles, pervading the film, being supplied in large numbers and also being of small enough dimensions to escape individual attention of the eye except when colored, and the particles giving a continuous efiFect in the layer where adjacent particles are colored, so that printing of high visual resolution can be made thereon.

FIG. 3 is a flow diagram of the process steps in the preferred utilization of the sheet.

FIG. 4 is a structural representation of the dye.

TH'E SHE'ET OF FIG. 1

This sheet is made by coating onto a substrate, such as paper, a hot melt of a 2%, by weight, solution of the specified chromogenic material in wax of the selected eligible class identified by being solid at room temperature and melting beginning at approximately 40 degrees centigrade, which is above the maximum temperature of use in normal living environment. The cooled, dried, and solidified coating preferably should be about 1 to 3 mils in thickness, but the thickness can be somewhat more or less as desired.

The preferred wax is ethylene-glycol-monostearate, which melts at about 60 degrees centigrade.

THE SHEET OF FIG. 2

This sheet is made as follows:

(I) A solution is made of 50 parts, by weight, of ethylene-glycol-monostearate heated to 60 degree centigrade and 2 parts, by weight, of the specified chromogenic material.

(II) There are blended together in a high-speed mixer 2 parts, by weight, of methyl cellulose with sufficient propyl groups to make it hot-water-miscible, and 298 parts of water, at to degrees centigrade.

(III) The warm wax solution of I) is emulsified in the warm aqueous dispersion of (11) to form a wax-inwater emulsion of creamy consistency.

The system is kept by any suitable means from assuming an acid condition.

The emulsion resulting from step (Hil) is coated on a substrate, such as paper, cooled, and dried, enough being used to leave a solid coating of 1 to 3 mils in thickness.

As substitutes for the specified wax of sheets (I) and ('11) may be mentioned parafiin wax, micro-crystalline wax, carnauba wax, beeswax, spermaceti, and fatty acid esters.

USES OF THE NOVEL SHEET Either of the sheets described has the property of the layers becoming sensitized on being heated above 40 degrees centigrade so as to respond to ultraviolet light, said response condition being recognizable by the development of a strong magenta color in the layer area receiving the ultraviolet light. Strangely enough, the sensitization, while caused by heating the layer for a short time to 40 degrees centigrade (or higher), persists a matter of minutes or hours after the sheet has returned to room temperature20 degrees centigrade 1-10 degree centigrade. The solution of the dye into the molten wax and its subsequent recrystallization time are thought to be the reason for this. Once the magenta color is formed, the layer as a whole, with the substrate, is further heated, which causes the magenta-colored areas to become blue. The artificial heating is stopped as soon as the blue is well developed. The so-developed blue color is irreversible by green or longer-wave-length visible light at ambient temperature but if the heating is continued for more than several seconds, the blue color will be decreased in intensity.

In a preferred use of the invention as a whole and as to its various aspects, a print-making employing the sheet of BIG. 2 will be specified as Example I.

Example I In this example, a sheet of paper sensitized with the novel composition shown in 'FIG. 2 is heated for two seconds between the plates of a hot platen press, having a platen temperature of 70 degrees centigrade, and then is subjected through a negative photograph transparency to a linear gas are lamp discharge radiation rich in 3,500 to 4,000 Angstroms. This exposure to ultraviolet light turns the sheet to a magenta color in areas corresponding to the light areas of the negative, tapering off in continuous tone to where the dark areas of the negative leave the sheet unexposed and colorless. The sheet then is subjected to heating in the same hot platen press for five seconds, which turns the magenta areas to a blue of corresponding intensity. This print is a positive in blue on a white background.

Example II This is exactly the same process as in Example I but carried out with the sheet of FIG. 1.

Example III In this example, certain selected areas of the magenta image of the sheet of Example I are subjected to green light before the layer is fixed to erase a corresponding part thereof, and thereafter the sheet is fixed by heat, as explained.

Example IV This example is like Example III, except that the sheet of FIG. 1 is used.

Example V This is the same as any of the preceding examples, except that a two-tone negative is used.

Example VI The uncolored sheet of FIG. 1 is sensitized in the hot platen press and then converted all over to the magenta sensitized condition by being flooded with the specified ultraviolet light. This sheet may be selectively and differentially erased by green light controlled in any manner, the remaining magenta areas being fixed as in Example I by heating of the whole layer.

Example V-II A sheet, like the sheets of FIG. 1 and 2, that bears fixed images may be subjected to heat-sensitization to render the background colorless areas sensitized and then subjected to ultraviolet light patterns to exhibit the added data in magenta color, after which the sheet undergoes the five-second heat treatment to fix the image--in adda-frame manner; that is to say, the addition of data may be made at any time to any unused area.

Example VIII If the magenta data is present as a two-color image or as a tone variation, in either an exposed FIG. 1 or FIG. 2 sheet-i.e., a variation in intensityits erasure may be made partial as to areas by timing the exposure to green light, the intensely magenta areas persisting in the green light after the weak magenta areas have disappeared.

Example lIX The time of exposure of a magenta area through a continuous tone negative determines the part of the area to be sufficiently printed to show blue development on heating. This is one other method of controlling selectively what is to be printed from a light control mask.

Example X In this example, using either the sheet of FIG. 1 or that of FIG. 2, the printing with ultraviolet light into magenta-colored areas may be controlled in one area by a negative transparency and in another area by a positive transparency. Obvious combinations are the use of superimposed negative transparencies used in any combination.

Other obvious modes of use of the wax layer or compositon consist of variations in erasure and fixing exposure both areawise and by variation in temperature.

Example XI The sheet of either FIG. 1 or FIG. 2 may be controlled as to areas of sensitization by thermographic means in which a master sheet bearing data in terms of infrared-radiation-absorbing characters is placed in contact with the wax layer, to form a pair; then the pair is subjected to infrared radiation, which results in the appearance of corresponding magenta-colored sensitive areas in the waxy layer. When subjected to ultraviolet light and heat, the data is fixed in a blue color in the waxy layer.

The magenta areas of this example are subject to erasure in the before-specified manner, either selectively or totally, and are fixed with the same degree of selectivity by applied heat to bring the layer, or an area thereof, to the fixing temperature for the longer period of time.

The thermography heating to sensitize the sheet may be accomplished by the reflex technique, if desired, in which the infrared light is first passed through the docu ment to cause the printed data, which is printed in infrared-absorbent ink, to become hot and activate the waxy layer to become magenta in color.

The application of heat in the examples has been by hot plate or thermographic means, but optically-directed infrared light directed against an absorption converter may be traced in any pattern to produce a corresponding heat pattern against which the novel waxy layer may be positioned in contact to be colored magenta according to the pattern. In another form of heat application, a branding-iron type-i.e., heated type-may be used to apply heat conductively to the novel sheet.

The application of green light may be controllled optically by stationary or moving beam to erase a selected area of the magenta-colored area.

An additional novelty of the invention is carried out where the steps are performed simultaneously in the sense of employing certain operating steps at the same 'Jime. Ultraviolet light may be projected in a pattern onto a sheet at the same time it is being heated to sensitize it thereto, and the heating may continue on to fix the print made by the ultraviolet light.

It will be self-evident that there are numerous combinations in which the novel sheet may be used with light and heat controlled in various manners, but the examples given are deemed a sufficient disclosure to claim the novel sheet and its use in broad terms.

What is claimed is:

1. A process of forming record marks distinguished visually by coloration of various pattern areas in a layer of wax taken from the group of Waxes consisting of mineral wax, vegetable wax, synthetic fatty ester wax, and animal wax, such wax being characterized by having a solid state in the range of 20 degrees centigrade :20 degrees centigrade and a liquid state above 40 degrees centigrade having dispersed in it the compound 6-nitro-1,3,3-trimethylbenzoindolinospiropyran, including the steps of (a) heating the layer in the desired pattern areas to its melting point to sensitize it to ultraviolet light;

(b) While said areas are still sensitized, subjecting the layer to ultraviolet light of the desired pattern to form a magenta precursor image; and

(c) reheating the layer to a temperature whereat the image turns blue, thereby fixing it.

2. The process of claim 1 wherein the whole layer is heated in step (a).

3. The process of claim 2 wherein the ultraviolet light is applied by means of a light control device.

4. The process of claim 2 wherein the ultraviolet light is applied enough a control mask and before step (c) is performed desired portions of the magenta area are erased to a colorless state by application of green light.

5. The process of copying a document having data recorded thereon in terms of image-representing areas that are absorptive of infra-red radiation while the background area is substantially non-absorptive thereof, ineluding the steps of (a) forming a pair by placing the document in heatconducting contact with a copy sheet comprising a heat-meltable wax layer taken from the group of waxes consisting of mineral wax, vegetable wax, synthetic fatty ester Wax, and animal wax, such wax being characterized by having a solid state in the range of 20 degrees centigrade :20 degrees centigrade and a liquid state above 40 degrees centigrade in which 6'-nitro-1,3,3-trimethy1benzoindolinospiropyran is dispersed; (b) directing infra-red radiation against the pair in sufficient amount to heat the infra-red-absorptive matter of the document to sensitize the copy sheet to a point where the portion of the wax layer in contact with the infra-red absorptive matter will turn under subsequently-applied ultraviolet light to a magenta color; (0) flooding the layer with ultraviolet light; and (d) heating the wax layer until the magenta areas turn blue. 6. The process of copying a document bearing data as infra-red-absorptive characters, including the steps of (a) heating a copy sheet provided with a Wax layer taken from the group of Waxes consisting of mineral wax, vegetable wax, synthetic fatty ester Wax, and animal wax, such Wax being characterized by having a solid state in the range of 20 degrees centigrade :20 degrees centigrade and a liquid state above 40 degrees centigrade having 6-nitro-1,3,3-trimethylbenzoindolinospiropyran dispersed in it to a temperature at which the Wax is substantially melted;

(b) subjecting the layer to ultraviolet light to turn the whole area of the layer to a magenta color;

((1) placing the document against the layer in heatconducting contact to form a pair; and

(d) subjecting the pair to infra-red radiation to turn the magenta color to blue in areas in heat-conducting contact with the infra-red-absorptive data.

References Cited UNITED STATES PATENTS 2,949,381 8/1960 Steinhardt 106-272 3,016,308 1/1962 Macaulay 117-361 3,042,519 7/ 1962 Wainer 96-90 3,141,404 7/1964 Newman 250-651 3,242,122 3/1966 Cheng 260-32611 3,293,055 12/1966 Baum 250-651 3,293,060 12/1966 Harbort 117-369 3,328,167 6/1967 Owen 96-67 FOREIGN PATENTS 810,401 3/ 1959 Great Britain.

OTHER REFERENCES Day, I. H.: Thermochromism, Chem. Rev., vol. 63, 1963, pp. -70.

NORMAN G. TOROI-IIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner.

US. Cl. X. R.

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