US2810661A

US2810661A - Transfer sheet

Info

Publication number: US2810661A
Application number: US431100A
Authority: US
Inventors: Douglas A Newman; Allan T Schlotzhauer
Original assignee: Columbia Ribbon and Carbon Manufacturing Co Inc
Current assignee: Columbia Ribbon and Carbon Manufacturing Co Inc
Priority date: 1954-05-20
Filing date: 1954-05-20
Publication date: 1957-10-22
Anticipated expiration: 1974-10-22

Description

pol e Thylene LO Oct. 22, 1957 D. A. NEWMAN ET AL 2,810,661

TRANSFER SHEET Filed May 20, 1954 FLEXIBLE PLASTICL FOUNDATION (2.9. celluiose accfare,

TRANSFER COATING i2 INCLUDING ETHYL cELLuLosE,o|L-

MODlFIED GLYCOL SEBACATE AND PIOMENT.

ferephfha \aTe) IN V EN TOR. .PoqyZas A. A ewman 6 kijZ L JQTTOENEYS TRANSFER SHEET Douglas A. Newman, Glen Cove, and Allan T. Schlotzhauer, Locust Valley, N. Y., assignors to Columbia Ribbon 85 Carbon Manufacturing Company, Inc, Cove, N. 1., a corporation of New York Application May 20, 1954, Serial No. 431,131

4 Claims. (Ci. 117 -36) This invention relates to transfer sheets or strips, the ink composition coating therefor, and to the method of making the same.

Transfer sheets generally have a suitable foundation carrying a pigmented coating and are used to transfer inscriptions or images made on or over the sheet to another sheet, as for instance, in the making of carbon copies. The image is usually applied by a printing instrumentality such as a typewriter on the foundation and the coating on the other surface thereof is transferred to the copy sheet.

In the event that the transfer sheet is to be used as a so-called mechanical negative for reproducing images in a photographic or photo-projection process it is desirable that all the coating be separable from the foundation in order that light may pass through the imaged areas. In addition the flexible foundation should be homogenous, smooth and transparent, as is cellulose acetate or cellophane, in order not to impede the free passage of the light.

Heretofore in endeavoring to meet the requirements of a transfer sheet which would be capable of both transferring an image and producing a negative, the coating on the face of a transparent foundation was composed of a soft wax-like pigment-carrying substance. But, a difliculty encountered with the use of such a coating was that it was very smudgeable when transferred in image form and, furthermore, would not sharply break away or stencil from the foundation with sufficient definition to produce a sharp clear image. In endeavoring to overcome these difliculties it has been found that a harder pigmented coating did not readily adhere with suflicient tenacity to the smooth, non-porous foundation to avoid flaking and cracking. In order to overcome these objections it had been suggested that a bonding coating be applied intermediate the foundation and the transferable coating, but such an intermediate coating involved added labor and cost and besides madeit more difficult for the light to be transmitted through the sheet when it was used as a negative.

Furthermore, when transfer sheets having a soft transferable coating of a wax-like substance are used to make a negative, the coating is liable to soften and run at the high temperatures to which it is subjected by the light rays.

These difficulties have been overcome by the present invention by providing a coating combining the colorbearing material and a cellulose heat-resistant base instead of the usual wax base, the cellulose base being modified by the addition of a plasticizer which will render the coating adherent to a smooth non-porous foundation and yet be more adherent to a copy sheet than to the foundation, so that when the coating is subjected to image-forming force, will separate from the face thereof in image form and adhere to the copy sheet. We have found that those film-forming celluloses which are normally highly cohesive and which tend to have more ice cohesion than surface adhesion for other materials when dry may be modified by some plasticizers to overcome the normally cohesive properties and therefore become more frangible, permitting the imaging portion to cleanly break-away from the adjacent portion of the coating. Such materials which may be used as a base are the usual cellulose binders such as lacquers and the like, and we have discovered that these cellulose materials can be altered to produce the above results by the addition of an oil-modified glycol sebacate which reduces the cohesive properties and gives a relative increase in the adhesive properties.

A feature of this invention accordingly is the provision of a transparent, smooth, flexible foundation with a coating consisting of a base comprising a lacquer base for the pigmented composition including an oil-modified glycol sebacate to impart to the base properties which will make it adherent to the foundation but capable of transference to a copy sheet When subjected to an imageforming force.

in carrying out this invention the lacquer and the glycol sebacate are suspended in solution by a common volatile solvent such as one of the aromatics. The solvent is volatile to the extent that it will retain the lacquer and glycol sebacate in suspension until ready to be cast and when cast can be driven off from the coating by evaporation. An example of a solvent which has been found very satisfactory and can be used to suspend the lacquer and glycol sebacate is toluol.

in our joint application, Serial No. 411,272, we have disclosed our discovery that if the lacquer base be modified to provide a discontinuous adhesive coating, it can e rendered sufficiently frangible to permit its transfer under force applied by an inscribing instrument to another member such as a copy sheet. To accomplish this it required, according to our prior disclosure, the use of two solvents such as alcohol and water, and as a result certain dyes and pigments which were not dissolved in the solvents did not give satisfactory results. We have since discovered, as disclosed herein, that other coating producing solvents produce comparable results with the addition that they accept other pigments which were not acceptable to water and alcohol solvents. For instance, we have found when toluol is used as one of the solvents, carbon black may be used as one of the pigments and this is of great practical advantage since black copies are preferable to colored copies. In addition, black produces a more efficient mechanical negative.

A feature of the present invention is, therefore, a provision of a cellulose coating on a flexible foundation containing carbon black or other pigments insoluble in water or alcohol which is rendered sharply frangible under the force of inscription elements and under the force of type elements and has greater adhesion for a suitable copy sheet than it has for its foundation.

The mixture of solvent base material of the present invention may also be colored by the admixture of suitable pigments and/ or dyes in proper proportions according tovthe purpose for which the transfer sheet is to be used. While a wide variety of pigments and dyes in addition to carbon black may be used, especially good results have also been obtained using pigments of a nonporous and non-absorptive character, e. g., metal powders known in the art as bronze powders.

In selecting a suitable foundation sheet which is trans parent and may be used as a negative when the pigmented coating in image form has been removed therefrom, we have discovered that a film made from polyethylene terephthalate, known under the trademark of Mylar (i. e. du Pont de Nemours and Co.), produces excellent results. The cellulose coating readily adheres to the sur-- face thereof and when the resulting transfer sheet is subjected to image-forming pressure, an image will more cleanly break away from the surface and the surrounding coating than When other transparent foundations are used, resetting in a superior image on the copy medium and an excellent negative.

A further feature is the provision of a coating made according to the invention on a strip of Mylar to prodl'ice' a transfer sheet.

Additional features and advantages will hereinafter appear.

In the drawings:

Figure 1 is a view of the transfer sheet of the present invention;

Fig. 2 is a view of the portion of the transfer sheet showing the negative left when the pigment coating is transferred therefrom to another medium.

Fig. 3 is a magnified sectional view of the transfer sheet'being displaced from a copy medium showing an image transferred from the transfer sheet to a copy medium.

The foundation of the transfer sheet of the present invention is molded or formed of a solidified resin, synthetic resin or other similar substitute material to be substantially homogehous, smooth-surfaced, non-porous, transparent, and which will in sheets of such thicknesses as are practically employed for the purposes herein intended be tough, strong, flexible and non-plastic at temp'eratures in which it may be intended to be used. By way of example, it may be mentioned that cellulose acetate sheets, cellophane and especially Mylar (du Pont de Nemours and Co.), have such properties and have been satisfactorily used in practicing this invention. Because the foundation is substantially smooth and nonporous, the coating which carries the color-bearing pigment must be sufficiently adherent to bond to the surface under normal handling conditions and when subjected to an image-forming force must be readily separable therefrom. The coating additionally must be sufliciently flexible so that when it is rolled or handled in conjunction with a typewriter or image-forming machine it does not readily flake or crack. In the event that flaking or cracking occurs, the sheet would lose its value as a negative because the flaked and cracked portions would appear when reproduction of the negative is made in a photographic process.

An example of a coating mixture made according to the present invention and one which is presently preferred is given by the following formula:

The proportions shown are intended to be illustrative only and not necessarily limiting. For example, under some circumstances the carbowax may be entirely eliminated inasmuch as the carbowax only acts as a plasticizer and does not affect the adherence or transfer properties of the coating under normal circumstances. Furthermore any suitable pigment and/or dye may be used in place of the Peerless Black, depending on the use for which the completed transfer sheet is intended.

The ethyl cellulose and carbowax (if used) are dis solved in the toluol and thereafter the oil modified glycol sebacate Paraplex AL 111 is added thereto and thoroughly intermixed until all the ingredients are in solution. The color-bearing pigment, in the instant example, Peerless Black, is mixed with'mineral oil into a paste and theerafter thoroughly admixed with the solvent ethyl cellulose and Paraplex AL 111.

The coating 12 is then applied cold to the foundation sheet, preferably Mylar, and the solvent allowed to evaporate therefrom. The residue of the solution forms an adherent layer on the flexible foundation but the layer may be separated from and transferred in image form to a copy sheet when subjected to an image-forming force.

The addition of the Paraplex AL 111 to the ethyl cellulose renders the coating more adhesive and creates a greater affinity for the copy sheet than for the foundation sheet. Furthermore, the Paraplex changes the molecular structure of the ethyl cellulose in such a manner that the ethyl cellulose becomes more frangible, and when subjected to image-forming force will sharply break away from its adjacent surface to give a more clear image than heretofore possible. Although it is not quite understood how the molecular structure is changed, it is believed, however, that the addition of the Paraplex is not completely miscible with the ethyl cellulose and thus inhibits the growth of the chain of molecules of the ethyl cellulose and only allows short chains to form, creating the ready frangibility of the layer when image-forming force is applied thereto.

When a transfer sheet formed as described above is placed in contact with a copy-receiving surface and printing er writing pressure is applied thereto, it is found that the coating transfers completely from the foundation sheet to the copy surface 13 making a sharp, clear, legible mark 14 thereon. The transferred image will adhere tenaciously to the surface and will resist smudging, and we have found this to occur with the same results on either fibrous or non-fibrous copy mediums. Transparent foundation sheets coated with compositions according to the present invention are thoroughly resistant to heatsoftening in all climates; they are also free of any tendency toward increased tackiness under pressure and hence will be noticeably cleaner handling than when wax base transfer films are used; The transfer sheets produced with the compositions of the present invention are free of rancidi'ty-producin'g substances and do not dry out over long periods of time and hence have excellent storage qualities.

In the event that the transfer sheet is to be used as a mechanical negative after an image has been transferred therefrom, the coating, when subjected to high temperatu'res 'as required in the making of a photographic print or the projection 'of a slide, will be immune to the high temperatures and as a result can be repeatedly used.

While the invention has been particularly described in connection with a coating for a transparent foundation sheet, it will be understood that the coating may be applied to such non-transparent foundations as are normally used iir'the manufacture of transfer sheets, and the advantages of the coating formed according to this invention when applied to such conventional foundation sheets will, accdrdi gly, enure thereto.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

We claim:

1'. As a new article of manufacture, a transfer sheet having a foundation sheet of the class consisting of cellulose acetate, cellophane and polyethylene terephthalate, and a releasably adhering transferable marking layer on one sur'face thereof consisting of an ink composition comprising a pigment dispersed in a cellulose base made up of ethyl cellulose and an oil-modified glycol sebacate in the ratio of 2:1 by weight, said glycol sebacate rendering saidnormally cohesive ethyl cellulose releasably adherent to said foundation and imparting to said coating a predeterminat'e frangibil'ity whereby when image or writing force is applied on said transfer sheet localized portions of the coating upon which said force is applied will separate completely from said surrounding coating and release from said foundation and bond on an underlying receiving medium.

2. The invention as defined in claim 1 wherein said 2,308,676 Cummins Jan. 19, 1943 pigment comprises carbon black. 2,508,725 Newman May 23, 1950 3. The invention as defined in claim 1 wherein said 2,589,657 Auer Mar. 18, 1952 pigment comprises bronze powder.

4-. The invention as defined in claim 1 wherein said 5 FOREIGN PATENTS foundation sheet is transparent whereby when the portion 424 495 Great Britain 15 1935 of the marking layer is removed therefrom the sheet forms a mechanical negative for photographic reproductions. OTHER REFERENCES Synthetic Resins for Coatings, Resinous Products and References Cited in the file of this patent 10 Chemical Co. 1947, PP. 47 and 49.

UNITED STATES PATENTS 345,220 Duval July 6, 1886

Claims

1. AS A NEW ARTICLE OF MANUFACTURE, A TRANSFER SHEET HAVING A FOUNDATION SHEET OF THE CLASS CONSISTING OF CELLULOSE ACETATE, CELLOPHANE AND POLYETHYLENE TEREPHTHALATE, AND A RELEASABLY ADHERING TRANSFERABLE MARKING LAYER ON ONE SURFACE THEREOF CONSISTING OF AN INK COMPOSITION COMPRISING A PIGMENT DISPERSED IN A CELLULOSE BASE MADE UP OF ETHYL CELLULOSE AND AN OIL-MODIFIED GLYCOL SEBACATE IN THE RATIO OF 2:1 BY WEIGHT, SAID GLYCOL SEBACATE RENDERING SAID NORMALLY COHESIVE ETHYL CELLULOSE RELEASABLY ADHERENT TO SAID FOUNDATION AND IMPARTING TO SAID COATING A PREDETERMINATE FRANGIBILITY WHEREBY WHEN IMAGE OR WRITING FORCE IS APPLIED ON SAID TRANSFER SHEET LOCALIZED PORTIONS OF THE COATING UPON WHICH SAID FORCE IS APPLIED WILL SEPARATE COMPLETELY FROM SAID SURROUNDING COATING AND RELEASE FROM SAID FOUNDATION AND BOND ON AN UNDERLYING RECEIVING MEDIUM.