US 3873666 A
A process for preparing transparencies useful for further photoreproduction, e.g., in photogravure, lithographic, or offset techniques. These images are prepared by imparting impressions of the background portions of xerographic images on polyethylene film layers juxtaposed therewith. The transfer is effected by subjecting the juxtaposed layers to heat and/or pressure.
Description (OCR text may contain errors)
O United States Patent 1 1 1111 3,873,666 Lerman 1 1 Mar. 25, 1975 15 1 PROCESS FOR THE PREPARATION OF 3.311.692 3/1967 Baird 264/293 TRANSPARENCIES FOR USE IN PHOTOREPRODUCTION FOREIGN PATENTS OR APPLICATIONS 1,168,273 10/1969 United Kingdom 264/293  lnvemori Frank Lermantcmcllmatltohlo 419,620 1934 United Kingdom 264/293  Assignee: National Distillers and Chemical Corporationv New k Primary E.\'uminer-Robert F. White  Filed: 11 1972 Assistant lirumi/wrGene Auvillc Attorney, Agent, or Firm-Allen A. Meyer, Jr.  Appl. No: 314,059
Relatetl US. Application Data  ABSTRACT  Contmuation-m-part of Ser. Nos. 63,950. Aug. 14,
1970, abandoned, and Ser. No. 311,173, Dec. 1, A process for preparing transparencies useful for fur- 1972. Pz1t.No.3.796,571. ther photoreproduction, e.g., in photogravure, lithographic, or offset techniques. These images are pre-  US. Cl. 264/219, 264/293 pared b imparting impressions of the background  Int. Cl. 82% 1/02 po tions of xerographic images on olyethylene film Field of Search 264/293. 219 layers juxtaposed therewith. The transfer is effected by subjecting the juxtaposed layers to heat and/or  References Cited pressure,
UNITED STATES PATENTS 2442,4115 6/1948 Fornwalt 264/293 5 Clams Drawmgs PROCESS FOR THE PREPARATION OF TRANSPARENCIES FOR USE IN PHOTOREPRODUCTION REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 63,950, filed Aug. 14, 1970 and now abandoned entitled Process for the Preparation of Polyethylene Transparencies for Use in Photoreproduction, and recently filed copending application Ser. No. 311,173, filed Dec. 1, 1972 now U.S. Pat. No. 3,796,571 entitled Process for the Preparation of Polyethylene Transparencies for Use in Photoreproduction.
Application Ser. No. 63,950 discloses techniques for the preparation of transparencies on polyethylene film substrates which are suitable for use in photoreproduction and which are prepared by (l) the transfer to such substrates of fixed polyethylene images, (2) the transfer thereto of textured impressions of the non-imaged portions of an original, or (3) the transfer of a releasable layer having a suitable image formed therein. Each such technique is incorporated by reference herein. The aforesaid recently filed copending application more fully describes and claims the first such technique. This application more full describes and claims the second such technique.
BACKGROUND OF THE INVENTION This invention relates to a process for the preparation of transparencies from xerographic images, which transparencies may thereafter be utilized as masters in photogravure, lithographic or offset-printing opera tions.
As used herein, the term transparency is intended to refer to an image suitable for photoreproduction and incorporating image elements or areas of varying densities, on or in a light-transmissive (including translucent) substrate.
In many photoreproduction processes, a positive or negative transparency bearing the image to be reproduced is required. In conventional black and white photographic printing, prints are made from negative transparencies, the black areas on the print representing the substantially light-transmissive areas of the transparency, intermediate tones representing intermediate densities of the transparency, and the white areas on the print corresponding to high densities of the transparency through which virtually no light passes. Thermographic duplication processes may also employ transparencies as originals, and rely for differentiation of the image-defining areas on the relative proportions of heat radiation transmitted through the transparency. Photogravure, photolithographic, and photo-offset processes form printing plates for use in gravure, lithographic and offset-printing by exposing a photosensitive surface through a transparency, and then treating the surface so as to etch, dissolve or otherwise remove or chemically modify the surface in accordance with the light-induced changes created therein by the exposure. The varying relief or intaglio, or oleophilic and hydrophilic, areas of the plates thus produced are capable, upon printing, of duplicating the image on the original transparency.
All the preceding photoreproduction processes require an original transparency which may be produced photographically. In many cases, however, the material to be duplicated is in the form ofa print, design or decoration in or on an opaque substrate, such as paper, metal, fabric or plastic. Duplication of such an original photographically requires that a negative be taken by a camera, the image developed, and the film processed, all of which is time-consuming, and requires cumbersome equipment.
Duplication procedures are also available which are capable of preparing reproductions of prints, decorations, designs or other images on a substrate by electrostatic (xerographic) or thermostatic (thermographic) printing. These procedures, however, generally produce a copy on an opaque substrate, which is not suitable for use in reproduction processes requiring an original transparency.
Procedures have also been described in the patent literature for forming transparencies by transfer from originals produced xerographically. Such techniques are disclosed, for example, in Carlson U.S. Pat. No. 2,990,278 granted June 27, 1961, and Mayer U.S. Pat. No. 3,275,436 granted Sept. 27, 1966. The techniques described in the Mayer patent may be carried out employing polyethylene-coated transfer sheets such as described in Van Dorn U.S. Pat. No. 2,855,324 granted Oct. 7, 1958.
The Carlson, Mayer and Van Dorn patents disclose the xerographic formation of an electrostatic powder image, the subsequent transfer of such image to a transfer layer and, optionally, the application of an additional material to the non-image portions of the transfer layer. Carlson teaches that the transfer layer is preferably of such a composition that it does not mechanically bond to the electrostatic powder image but rather forms only an intermediate support for the image prior to transfer to a third, and final, substrate therefor. Mayer, on the other hand, discloses that the transfer layer many adhesively receive the electrostatic powder image and that an additional film material may thereafter be adhered to such layer in the non-image portions defined by the electrostatic powder image thereon. Van Dorn describes the use of, for example, a polyethylene-coated transfer layer and indicates that, alternatively, the electrostatic powder image transferred to such layer may be heat fixed thereon.
Each of the preceding techniques is directed to the application of an unfixed (impermanent) electrostatic powder image layer, which may be followed by further manipulation, e.g., by transfer to yet another receiving layer Carlson, or by the application of a coating to the non-imaged portions thereof Mayer, prior to fixing the final image. As acknowledged by Carlson, such manipulations may result in smudging and/0r offsetting of the electrostatic powder image during the transfer operation as well as in any subsequent manipulations thereof. The clarity of the final image desired for photoreproductive purposes may thus be substantially impaired.
In the aforesaid recently filed copending application, a process is described and claimed for effecting the formation of a transparency, suitable for use in further photoreproduction, by the transfer of a fixed polyethylene image formed, for example, xerographically. It is a principal object of the present invention to provide a further relatively simple and yet precise technique for effecting the formation of transparencies from xerographic originals which, like that described in the said recently filed copending application, is not subject to image smudging and/or offsetting during use, and provides clear and well-defined transparencies which are quite suitable for subsequent photoreproduction.
SUMMARY OF THE INVENTION In accordance with the present invention, a process is provided for the preparation of transparencies suitable for use in photoreproduction, which comprises providing a rough, highly textured substrate having a smooth non-olefinic xerographic toner, pigment or ink image formed thereon, contacting the substrate with a polyethylene film, and successively heating and cooling the juxtaposed layers to form and fix textured impressions of the non-imaged areas of the substrate in the film. Finally, the polyethylene film is stripped from the original substrate a fixed negative transparency (negative with respect to the image on the original substrate) suitable for use in photoreproduction thereby being formed on the film.
By producing the initial xerographic image on a rough highly textured substrate, and forming such image in conventional manner utilizing a non-olefinic xerographic toner, pigment or ink, an orginal is provided which may readily be utilized in accordance with the present invention to effect the formation of a polyethylene transparency representing solely the textured, non-imaged portions of the original. Thus, when the polyethylene film is placed in contact with the imaged substrate, and the juxtaposed layers are subjected to successive heating and cooling, an impression of the rough-textured background areas of the original is imparted to the film without, however, anytransfer of the smooth, non-olefinic imaged areas to the film. In this manner a reversal image is produced which accurately reproduces the textured background provided by the original substrate. Moreover, since no toner, pigment or ink is transferred in the operation, the transparency produced is not subject to smudging or offsetting and is, therefore, quite suitable for subsequent photoreproduction.
PREFERRED EMBODIMENTS OF THE INVENTION As indicated hereinabove, any suitable rough, highly textured substrate may be used in the practice of the present invention. Substrates so useful may comprise paper; wood; metal, such as stainless steel, aluminum, chromium'plated steel, nickel-plated steel or cadmiumplated steel; stone; fabrics, both woven and nonwoven, made of natural or synthetic fibrous material, or blends thereof; leather; ceramics and porcelain; glass; and opaque of translucent plastic materials such as nylon, Teflon (polytetrafluoroethylene), polycarbonates, polystyrene; synthetic rubbers or other elastomeric materials; or cellophane or regenerated cellulose. By appropriate choice of the textured substrate any desired esthetic effect may be obtained. For example, decorative woods, e.g., pine, birch or teak, having designs imprinted thereon may be utilized in the present process to provide transparencies exhibiting both the imprint and the texture of the original substrate.
The xerographic image applied to the substrate may be formed in any manner, and utilizing any materials, known to be useful for such purpose in the xerographic art. Apart from the electrostatic characteristics necessary for such materials, they must provide a smooth surface which does not adhere to the polyethylene film when juxtaposed therewith and successively heated and cooled in accordance with this process. Xerographic toners so useful include various types of nonpolyolefins, e.g., copolymers of styrene and acrylic acid esters, or polyacrylates per se. Other toners, or inks and pigments similarly used for the formation of xerographic images may, alternatively, be utilized, provided that they meet the additional requirement noted hereinabove.
The xerographic image thus formed is applied to the substrate and fixed in conventional manner. The resulting fixed, non-smudging image is smooth and nonadherent to polyethylene films and is, therefore, quite suitable for use in the present process.
The polyethylene film to which a reversed image of the xerographic original is imparted may be of any suitable grade or thickness. The use of films having gauges of from about 1 to 5 mils and prepared from resins having densities varying from about 0.913 to 0.96 is particularly suitable. Any polyethylene film materials may, however, be utilized so long as, upon juxtaposition with the original image and the application of heat and/or pressure thereto, the film material is softened and receives an impression of the textured background areas of the original therein.
In forming the impression it is desirable to press the initial image and the polyethylene impression or carrier film together at temperatures of from about to C. and with the application of pressures which may suitably vary from about 2 to 50 psig. Such heat and/or pressure may be applied in any suitable manner, e.g., manually, or by pressing the same between suitable platens or pressure rolls. When the image and film layers are thus juxtaposed they may be sandwiched between a pair of block-resistant film layers constituted, for example, of Mylar polyester film to facilitate the impression operation without blocking.
The juxatposed layers are thereafter cooled to temperatures of from about 90 to 25C., preferably within about 30 seconds of the initial application of heat and- /or pressure, to harden the film and thereby fix the impression of the textured background areas of the original therein. The two layers are thereafter stripped apart, leaving a textured reversal image permanently formed in the transparent polyethylene impression or carrier film and thereby providing the final transparency suitable for use in photoreproduction.
If desired, the contrast of the transparency thus produced may be increased by the addition of an opacifying agent, e.g., a suitable pigment or ink, which adheres preferentially to the textured portions of the transparencies formed as aforesaid.
The polyethylene film may, if desired, be laminated to a further transparent carrier film whereby to sandwich the textured image between the two films and thus protect it from damage during further use. The second carrier film may be bonded to the completed transparency in any desired manner.
The following example illustrates one preferred embodiment of the process of the present invention. It will be understood that the techniques described therein are illustrative only, and should not be construed in a limiting sense.
EXAMPLE A copy of a printed black and white magazine page was reproduced by an electrostatic copier, forming a fixed image of a copolymer of styrene-acrylic ester toner on a standard, uncoated bond paper having a highly matted texture. The image surface of the paper copy was placed in contact with a thin polyethylene film, the resulting sandwich was heated and then cooled, and the film was thereafter carefully stripped from the paper.
No transfer of the fused toner from the paper to the polyethylene film occurred. However, the texture of the paper was impressed on the film resulting in the formation of translucent areas in the film corresponding to the non-imaged portions of the original copy. The portions of the film corresponding to the black printing on the paper remained transparent, due to the smooth surface of the fused toner on the paper. Thus, a reversal image of the paper copy was formed in the polyethylene film, having transparent lettering formed on a translucent background and being quite suitable for use as a transparency for further photoreproduction. Use of the highly matted transparent paper as the substrate for the original copy was found important to facilitate imparting a relatively opaque texture to the polyethylene film contrasting with the transparent lettering corresponding to the printed matter in the original copy.
Various changes may be made in the preferred embodiment described hereinabove without departing from the scope of the present invention. Accordingly, the preceding description should be interpreted as illustrative only and not in a limiting sense.
1. A process for the preparation of transparencies for use in photoreproduction, which comprises:
a. providing a rough, highly textured substrate; applying to the substrate a smooth non-olefinic image constituted from one of the group consisting of fused xerographic toners, pigments and inks;
b. contacting the imaged side of said substrate with a polyethylene film;
c. heating the juxtaposed image and film layers to a temperature sufficient to soften the polyethylene film and thereby form textured impressions of the non-imaged areas of said substrate therein;
(1. cooling the juxtaposed layers to fix the textured impressions in said film; and
e. stripping the thus imaged polyethylene film from said substrate to form a fixed transparency suitable for further use in photoreproduction.
2. The process of claim 1, wherein the original image formed on said substrate is constituted on a copolymer of a styrene-acrylic ester or polyacrylate-type xerographic toner.
3. The process of claim 1, wherein said substrate is paper.
4. The process of claim 1, wherein said substrate and the polyethylene film layer are placed in contact by sandwiching the same between a pair of block-resistant film layers, and the resulting sandwich is subjected to heat and pressure to impress the textured surface of the substrate on the film without blocking.
5. The process of claim 4, wherein the block-resistant film layers are constituted of polyester sheets.
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