US2704977A - E reilly - Google Patents

Description

March 29, 1955 F. E. REILLY MAKING READY sTEREoTYPE MATRIX 2 Shets-Sheet l Filed May 20. 1952 F. E. REILLY MAKING READY sTEREoTYPE MATRIX March 29, 1955 2 Sheets-Sheet Filed May 20, 1952 5 Y Y mL E m WR m www m M w United States Patent() MAKING READY STEREOTYPE MATRIX Frank E. Reilly, Chicago, Ill., assignor to Electrographic Corporation, New York, N. Y., a corporation of Delaware Application May 20, 1952, Serial No. 288,937

4 Claims. (Cl. IUI-401.3)

The present invention relates to a novel and improved process for the underlaying of stereotype matrices for preparing made-ready stereotypes.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the steps, process and compositions pointed out in the appended claims.

The invention consists in the novel steps, process, compositions and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one form of apparatus for carrying out the process of the invention, and tgether with the description, serve to explain the principles of the invention.

Of the drawings:

Figure l is a schematic fragmentary sectional view of a sheet of underlay material in an early stage of the process;

Figure 2 is a similar view of an underlay sheet readyV to be applied to the back of a stereotype matrix prior to the plate casting operation;

Figure 3 is a schematic sectional and fragmentary view showing the underlay as applied to the back of a stereotype matrix;

Figure 4 is a similar view showing the application of heat and pressure to the assembled underlay and matrix;

Figure 5 is a similar view showing the made-ready matrix with the underlay adherent thereon after removal of the backing sheet, following the operation with heat and pressure; and

Figure 6 is a schematic sectional and fragmentary view showing the stereotype matrix with its underlay positioned within a vacuum casting box and with the cast stereotype plate still in the matrix.

The present invention has for its object the provision of a novel and improved process for the production of made-ready stereotype printing plates, and especially the production of made-ready stereotype matrices especially adapted for use in vacuum casting boxes. Still another object is the provision of a process of making stereotype matrices which can produce made-ready plates and which have the make-ready permanently adherent on the back of the matrix so that its permanent register is assured. A further object is the provision of a novel and improved underlay material which is especially adapted to be used in the preparation of made-ready stereotype matrices.

According to the process of the present invention, there is provided a sheet of composite underlay material which forms a part of the invention of the present application and comprises a sheet of relatively heavy material on whichis adherently supported a relatively thin sheet of make-ready tissue, the tissue being temporarily secured to the backing sheet by means of a temporary adhesive which is preferably of the kind which will release on being heated, while the other face of the tissue is coated with a layer of adhesive material which may be rendered adhesive and is preferably activated when it is subjected to heat.

An impression of the plate from which the stereotype matrix was formed and which is to be made ready is printed on the adhesively coated face of the tissue material, using an ordinary proof ink of a contrasting color, such as black. The tissue sheet is then cut through by hand to leave areas or patches whichy correspond to the high-lights of the picture to be reproduced, after which the remainder of the tissue is stripped from the backing sheet, leaving adherent on the backing sheet only those areas which correspond to the high-lights.

The underlay sheet is preferably provided near its four corners with register holes, which may be preformed in the sheet, and serve to locate the sheet while it is being printed with the proof impression which forms the guide by which the cutting of the tissue is carried out, or the register holes may be formed individually after the proof impression has been printed. They are usually outside of the impression area, and in any event serve to register the underlay sheet with the embossed impression in the matrix when the matrix and underlay sheet are being assembled.

The matrix is then laid face down on a flat surface and the face of the underlay sheet is laid against the back of the matrix, being registered thereby by observation of the embossed back of the matrix through the register holes in the underlay sheet, the printing plate being provided with similar impression areas so that the matrix has indentations showing through onto the back of the matrix and in register with the holes in the underlay sheet.

In order to facilitate the bonding of the underlay portions of the underlay sheet to the back of the matrix under the influence of heat and pressure, the face of the matrix is laid on a relatively thick sheet of resilient wadding material, such as exploded cellulose fibre supported on a flat heated platen, and another sheet of the wadding is applied over the upper or back surface of the underlay sheet. In this relation, an upper heated platen is forced towards the lower platen to exert substantial pressure on the assembled wadding, underlay sheet and matrix, sufficient pressure being used to firmly press the underlay sheet and matrix into adhesive contact without permanently deforming the matrix sheet or damaging the molded impression in the face thereof.

When the assembly has been sufficiently heated, thel upper platen is lifted, the wadding removed and the backing sheet may be removed from the back of the matrix, leaving the tissue underlay securely attached to the back of the matrix and in proper register with the highlight portions of the matrix.

The matrix is then placed in the casting box, and when the molten stereotype metal fills the casting box the matrix is deformed from its original shape in accordance with the tissue underlay so that the resulting cast stereotype has its highlight portions depressed below the normal level of the printing surface of the stereotype, and the resulting stereotype need only be trimmed and bored or otherwise interiorly finished to render it ready to be used as a made-ready printing plate.

The matrices prepared in accordance with the present invention have a distinct advantage over conventional matrices when used in a vacuum casting box. The tissue underlay is irmly and permanently united to the back of the matrix, so that as the vacuum is applied to the back of the matrix there is no tendency of the tissue to separate from the matrix sheet, blocking the holes in the backing member of the casting box which might cause damaging irregularities in the surface of the plate cast therein.

It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory of the invention but are not restrictive thereof.

Referring now in detail to the present and preferred manner of carrying out the process of the present invention, and the preferred and illustrative material used in the process; Figure l shows a sheet of the underlay material after the proof impression has been printed on its face, and after the tissue face of the nnderlay sheet has been cut through.

As embodied, the underlay material comprises a base sheet 10 of relatively heavy hard paper, such as oiled, hard manila paper preferably about 0.010" thick, which is cut in sheets of convenient size, on one face of which is positioned a sheet of relatively thin paper or tissue 12, of substantially uniform thickness and preferably about 0.003" thick. The thin paper 12 is adhesively secured to the base layer 10 by means of an adhesive 14 such as wax or paraffin which can be easily released, as by the application of heat. The outer face of the thin paper sheet 12 is coated with a layer of material 16 which can be rendered adhesive, as by the application of heat. Shellac, cellulose acetate and synthetic rubber-based adhesives are exemplary of the materials which are suited to and preferred for this use.

The releasable layer 14 need be only thick enough to hold the thin paper 12 to the backing layer 10 while the proof impression is being taken and while the thin layer 12 is being cut, and is usually less than 0.001" in thickness, while the heat activated layer of adhesive 16 is usually thicker, preferably from about 0.001 to 0.002, so as to insure a good bond between the thin paper 12 and the back of the matrix.

The underlay material comprising the sheets and 12 and their adhesive layers 14 and 16 are then provided with an impression of the printing plate to be duplicated by stereotyping, and this impression is made on the adhesive layer 16 in black or other contrasting printing ink.

The proof impression on the layer 16 then serves as a guide to the operator who cuts through the thin paper layer 12 with a sharp knife so as to sever these areas from the remainder of the sheet 12, the enclosed areas 18 corresponding to the highlight areas of the plate, or to those areas which need to be lightened in tone in the printing operation.

The sheets 10 and 12 are then punched with register holes 20, one near each corner of the underlay assembly and in definite relation to the proof impression on the adhesive layer 16, the location of the holes being preferably determined by means of similar register marks formed as an integral part of the plate being duplicated. Thereafter, the unwanted portions of the sheet 12 are removed from the backing sheet 10 to leave the isolated make-ready areas or patches 18 still adherent on the backing sheet 10. The unwanted portions of the sheet 12 are easily removed due to the relatively light adhesion created by the temporary adhesive holding the sheet 12 to the backing sheet 10.

The backing sheet 10 with its remaining areas 18 of the thin sheet 12 is then applied to the back of a previously formed matrix 30, with the areas 18 against the back of the matrix,

The matrix may be any conventional matrix, as ordinarily used for the production of stereotypes and formed from a fiong which usually comprises a plurality of laminated sheets of paper or other fibrous material with a filler of clay or the like. Such a matrix 30 bears on its face the molded impression accurately reproducing the surface of the printing plate to be duplicated, and as illustratively shown (in exaggerated form) may cornprise indented areas corresponding to the blacks or solidprinting areas 32, and halftone areas 34 for printing the lighter tones of the pictures. To further increase the con trast of the resulting impression from the stereotype, parts of the halftone areas should be modified in their height so that they will press with less pressure against the paper during the printing operation and thereby improve the quality of the resulting impression.

To relieve these highlight areas, it is usual to paste small areas of thin paper to the back of the matrix prior to the casting operation, or to use a complete sheet applied to the back of the matrix, the complete sheet supporting the thin paper make-ready elements. Where the thin paper patches are pasted individually on the back of the matrix, a great deal of time is consumed in handling the individual paper patches and in securing them in proper registered position on the back of the matrix, while where a separate backing sheet is employed to support these patches, it is usually necessary to modify the casting box so that the resulting cast plate has the desired thickness, and if the casting is carried out in a vacuum casting box, the backing sheet interferes with the application of the vacuum directly to the back of the matrix so that unevenness of the cast plate is the usual result. All of these disadvantages are overcome and avoided by the process of the present invention.

The assembled backing sheet 10 with the adherent patches 18, which are still adherent thereon due to the adhesive layer 12, and with the register holes properly registered with the embossed portions 36 of the matrix fibrous material, such as loosely matted cellulose fibres or exploded wood pulp, forming a layer which is initially 0.020" to 0.100" and preferably about 0.030" thick. Such material is generally available in sheet form as wadding or packing material, and for use in the present process is cut into a sheet which is somewhat larger than the area of the matrix 30. The layer of wadding 38 is supported on the lower heated platen of a press, and a second sheet or layer of similar wadding 40 is applied over the backing sheet 10 which overlies the matrix 30. The upper heated platen of the press is then lowered into firm, even contact with the upper layer of wadding 40 so as to deform the wadding layers 38 and 40 and to press the patches 18 with their layer of adhesive 16 against those portions of the back of the matrix to which they are to be attached under the influence of heat and pressure.

The temperature of the platens of the press will vary with the adhesive used in the layer 16, but in general and where heat-responsive adhesives such as shellac, cellulose acetate or synthetic rubber adhesives are used the temperature will vary from about 200 to about 325 F. and this application of heat and pressure is continued until the adhesive 16 has been rendered adhesive to the extent needed to firmly secure the patches 18 to the back of the matrix 30, and at the same time to cause the adhesive layer 14 to release the patches 18 from their supporting sheet 10. Where paratin or wax is used as the adhesive layer 14, this adhesive is usually largely absorbed by the backing sheet 10 as the adhesive is melted.

When sufficiently heated, the upper platen of the press is raised, the layer of wadding 40 is removed and the backing sheet 10 is easily separated, leaving the patches firmly united to the back of the matrix 30 and in proper registered relation with the indented face of the matrix, so that the highlight areas of the matrix are properly relieved or pushed downwardly in accordance with the patches 18.

Figure 5 illustrates schematically the completed matrix which is ready for the casting operation, while Figure 6 illustrates the matrix after it has been properly positioned within the casting box, the face of the matrix being the concave face when a curved plate is to be cast. In the casting box, the matrix 30 is pressed outwardly with its back seated against the concave face of the drag or outer member 44 of the casting box. The drag is shown as provided with suction holes 46 by which reduced air pressure or vacuum is applied to the back of the matrix to hold it in firm contact witth the concave face of the drag. In this position, the normal space is provided between the face of the matrix 30 and the cope 48 so that the plate 50 resulting from the cast metal pumped into the casting box is of normal thickness except at those points where the thickness has been reduced due to the underlay patches 18.

When the plate 50 has cooled sutliciently after casting, the casting box is opened and the plate is removed and passed to the usual plate finishing operations so that the plate is trimmed and interiorly finished to render it fully ready to be plated on the printing press, without further make-ready operations.

The invention in its broader aspects is not limited to the specific steps, process and compositions shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacricing its chief advantages.

What is claimed is:

1. A process of making ready stereotypes which oomprises cutting a thin underlay sheet in accordance with the printing surface of a printing plate to be duplicated by stereotyping while said sheet is temporarily adhesively supported by means of a thermally released adhesive on a backing sheet and is coated on its other side with a heat activated adhesive, removing unwanted areas of said thin sheet from the backing sheet, registering the remainder of the underlay sheet and the backing sheet with the back of a matrix, pressing and heating the matrix, underlay sheet portions and backing sheet to unite the matrix with the remainder of the overlay sheet and to raise portions of the matrix corresponding to the remaining underlay sheet portions, removing the backing sheet to leave the underlay sheet portions secured to the back of the matrix.

30 is then laid on a relatively thick layer 38 of resilient 85 2. A process of making ready stereotypes which comprises providing an underlay member comprising a backing sheet, a thin underlay sheet secured thereto by a thermally released adhesive and covered with a thermally activated adhesive, removing unwanted portions of the underlay sheet, registering the remainder of the underlay member with the back of a matrix, heating the underlay member and matrix under pressure to secure portions of the underlay sheet to the back of the matrix, to release the backing sheet from the underlay sheet portions and to raise portions of the matrix corresponding to the remaining portions of the underlay sheet, and removing the backing sheet to prepare the matrix sheet and underlay sheet portions for casting a stereotype plate.

3. A make-ready process as claimed in claim 2 in which the thermally released adhesive is a wax and the backing member absorbs a substantial portion of the wax when heated.

4. A make-ready process as claimed in claim 2 in which the underlay is a thin sheet, the backing member is a relatively thick sheet and the two are pressed and heated together between thicker resilient sheets.

References Cited in the lile of this patent UNITED STATES PATENTS

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