US3181206A - Composite matrix and method for making the same - Google Patents

Description

May 4, 1965 E. D. HAGNEY ET AL fsz COMPOSITE MATRIX AND METHOD FOR MAKING THE SAME Filed March 27, 1963 INVENTORS EDWARD D. HAGNEY BY MARVIN MEHLMAN United States Patent O 3,l8l,2l)6 CMPSHTE MATRIX AND METHOD FOR MAKING THE SAME Edward D. Hagney, Massapequa, and Marvin Mehlman, Bayside, NSY. (both National Electrotype C0., 227 IE. 45th St., New York, N.Y.)

Filed Mar. 27, 1963, Ser. No. M 9 Claims. (Cl. 22-5.5)

The present invention relates to a composite matrix to be used in forming printing elements and more particularly to a composite matrix composed of a plurality of individual matrices held together in such a way whereby the resulting structure may be used repeatedly in producing a large number of printing plates of substantially equal quality.

In stereotype plate casting machines, for example, the printing elements or plates are formed by pouring molten metal into a casting box in which a matrix having depressions on one side, corresponding to the particular letters or pattern desired to be reproduced on the plate, has been previously placed. The matrix is secured in the casting box by clamps and may be held against one of the interior walls of the casting box by suitable means such as vacuum so as to prevent the matrix from buckling and to provide a space for the molten metal from which the plates are to be cast. As the molten metal within the casting box is allowed to cool, it Will form a plate having a surface with the same letters or pattern as that on the matrix. The pattern on the plate will, however, be raised as contrasted to the relief of the matrix and, of course, will be the reverse of that on the matrix. The resulting plates after conventional trimming operations may be placed directly onto the printing presses.

Sometimes it is desirable to use a composite matrix made up of a basic or primary and one or more secondary matrices connected together for use as a Single unit. For example, in printing tabloids, a composite matrix may be used to cast a printing plate representing two separate pages of the newspaper and such matrix may be formed separately from two individual matrices attached together as a unit for casting the single plate. Also, either or both of the individual matrices representing a single page may be made from a plurality of matrices. The number of situations where it may be desirable to form composite matrices as compared to single, one-piece matrices are numerous. Generally, composite matrices may be advantageously employed Where corrections or changes are to be made in the particular pattern of previously formed matrices. Where this is the case, the portions of the basic or primary matrix that are to be deleted may be removed and replaced by separately formed, secondary matrices containing7 the proper patterns. Alternatively, composite matrices may be desired where advertisements are to be included in the nal matrix; and here, if it is known in advance that the original or primary matrix is to carry an advertisement, the primary matrix may be provided during the forming operation with a blank space at the location where the secondary matrix is to be inserted. This blank space will then be removed and the secondary matrix attached in the space provided.

The term primary matrix as used herein refers to the basic matrix which is formed from one piece and to which a second matrix is attached; and may be a basic matrix which has had a portion or portions removed to accommodate separate matrices or may be an unmodified basic matrix to which a second matrix is merely attached as with tabloids, for example. The term secondary matrix as used herein is, or" course, the matrix which is to be attached to the primary matrix.

In attaching the primary and one or more secondary Patented May d, 1965 ice matrices together, it is desirable to eliminate any spacing between the adjacent edges of the matrices. This may be done in various ways. For example, the edges may be brought into line contact with each other or the edges may be overlapped in which case they are usually feathered to provide a composite structure having relatively uniform thickness. Whichever method of joining is used, the important result desired is to have the respective edges in complete abutment whereby an effective seal between the matrices may be effected.

lt is the present practice in constructing composite matrices in any of the ways described above to secure the primary and one or more secondary matrices together by means of shrinkable, cloth or paper backed adhesive tapes and to place the composite structure in a scorching oven for removing moisture contained in the individual matrices preparatory to use in the casting machines. Removal of the moisture has the effect of pre-shrinking the composite structure so that upon subsequent use in the casting machine, substantially no further change in size will occur. Since these tapes are shrinkable they are usually placed on the composite matrix before the scorching operation so that the heat of the scorching oven will shrink the tapes at the same time the matrices are shrunk. Very seldom, however, is the rate of shrinking of the tapes and each individual matrix the same. Consequently, the composite matrix may have the adjacent edges of the individual matrices spaced from each other and this is possible either when the edges have originally been positioned in line contact, overlapped or feathered. Furthermore, the tape itself will not be securely attached in the locations where it has shrunk to an extent diterent than that of the matrices; and repeated use of these composite matrices in the plate casting machine, with the high temperatures of the molten metal, will cause these tapes to shrink further, and, in addition, will cause them to burn and decompose. This, in turn, will result in a further separation of the tapes from the composite structure and eventually molten metal will leak between the individual matrices. When this happens, the plates will show irregularities and not be suitable for printing purposes; and before any more acceptable plates may be cast, the composite matrix will have to be reprocessed or completely replaced.

in casting stereotype plates from molten lead mixed with other stereotype metals, the temperatures generated in the casting box of the casting machine may range from about 550 F. to 600 F. and with these temperatures conventionally constructed composite matrices become unusable after only two or three plates have been cast. This disadvantage is of particular importance to large circulation newspaper publishing companies Where it is often desirable to cast upwards to twenty plates.

Another disadvantage found with conventionally constructed composite matrices using conventional tapes resides in the effectiveness of the bond uniting the tapes tothe matrices. This bond is usually effected by applying a pressure sensitive adhesive coating to one side of the tapes, but after repeated use of a single composite matrix in casting successive plates, the high temperature of the molten metal destroys the adhesive qualities of the coating. And, although the cloth or paper base portion of the tapes is disposed between the molten metal and adhesive coating,.it acts only in a limited way in preventing the heat generated by the molten metal from reaching the adhesive coating. With the resulting breakdown of the adhesive, .the tapes tend to separate from the matrix and as with shrinking or burning of the tapes, molten metal will be permitted to leak between the tapes and matrix. This separation of the tapes from the matrix is further emphasized due to the fact that the tapes presently used possess relatively high coeicients of friction and therefore tend to stick to the cast plates themselves as the latter are removed from the casting box.

A further disadvantage of presently constructed composite matrices used in casting plates has to do with their positioning within the casting box. Conventionally, the casting box of a typical plate casting machine may be provided along one side with orifice through which a vacuum is applied to hold the matrix accurately in position against this side while the molten metal is being poured and while the cast plates are being stripped from the matrix and from the casting box. It is apparent that in order to effectively hold a composite matrix in position by vacuum, it is important that it be substantially impervious. As mentioned above, however, the tapes presently used in joining the composite matrix together, deteriorate and pull away from the matrix after repeated use. It may readily be seen that when this happens, the vaccum will be weakened and in many situations weakened to such an extent that proper stripping of the plates from the matrix is no longer possible. Furthermore, the molten metal leaking behind the matrix may damage the vacuum apparatus. Of course, before this happens, the matrix itself would probably have been removed and replaced by a new one since the plates being formed would show objectionable imperfections. Nevertheless, when all of the above disadvantages are considered together, important problems present with todays plate casting procedures are brought directly to ones attention.

According to the teachings of the present invention, a composite matrix is constructed in such a way that the disadvantages present with conventionally constructed matrices used in forming printing elements are substantially eliminated. More particularly, the composite matrix of `the present invention includes a sealing tape having a base member which possesses high thermal insulating qualities and which is substantially non-shrinking and not deteriorating at the temperatures generated in the plate casting machine. In addition to this, the base member is coated with a fluorinated synthetic resin having a low coefficient of friction whereby the tape is prevented from sticking to the printing elements as they are removed from the matrix. The uorinated synthetic resin coating being relatively inert and impervious also resists attack and thereby protects the underlying adhesive. Finally, the adhesive used in securing the tape to the composite matrix is a pressure sensitive, silicone adhesive adapted for use over a wide temperature range.

The present invention also teaches a specific method of forming the composite matrix whereby a complete and permanent sealing of the tapes to the composite matrix is effected and whereby complete abutting of the adjacent edges of the individual matrices is assured.

A fuller understanding of the present invention will be obtained by a reading of the following detailed description and examination of the accompanying drawings of which:

FIG. 1 is a plan view, partially broken away, of a composite matrix constructed in accordance with the teachings of the present invention;

FIG. 2 is a perspective view of the sealing tape with a portion of the adhesive coating separated therefrom; and

FIG. 3 is a side view of the tape with the parts partially separated for clarity.

As shown in FIG. 1 of the drawings, the composite matrix, generally designated as l, comprises a primary matrix 2 on which news items 3, for example, appear in relief and a secondary matrix 4 containing, for example, a particular advertisement 5 which is desired to be incorporated onto the printing element. As with the text 3 on the primary matrix, the advertisement 5 will be in relief so that the printing elements formed from the composite matrix will have the desired printing surface raised for use on the printing press.

In the particular composite matrix shown in FIG. 1, the lower left hand corner of the primary matrix has been cut away along the edges 6 and 7 and this portion has been replaced by a single secondary matrix having edges S and 9 abutting, respectively, the edges 6 and 7. As stated above, however, the primary matrix may be an unmodified one-piece matrix to which a secondary matrix is merely added or may have more than one portion cut away for the insertion of a plurality of secondary matrices.

To positively seal the two matrices together, a tape 11 shown in detail in FIGS. 2 and 3 is applied over the edges 6, 8 and 7, 9. The tape itself comprises a base member 12 of suitable thermal insulating material coated or impregnated with a fluorinated synthetic resin material 13 such as polytetrafluorethylene and provided on one side with a silicon adhesive 14.

A strong non-stretchable and non-shrinkable, woven glass fabric about 3A of a'n inch in width which is capable of withstanding temperatures in the neighborhood of 1000" F., such as ECC-11408 manufactured by Owens- Corning Fiberglas Corporation is used as the base member; however, other widths and materials such as nonwoven glass fabric, Woven or non-woven asbestos, or metal such as copper and aluminum may be used. The characteristics these materials have in common is their ability to resist shrinkage and deterioration and any burning that would tend to be caused in coating them with the iluorinated synthetic resin and in forming the printing elements. These materials also possess the ability to act as thermal insulating barriers during the plate casting operation to substantially reduce the heat that would normally pass through the tape from the molten metal to the adhesive coating.

The preferred resin material used in coating or impregnating the base member of the tape 11 is polytetrafluoroethylene although it is also within the scope of this invention to use other fluorinated synthetic resins, if found desirable. Fluorinated synthetic resins possess a number of characteristics that make them particularly suitable for use in the present invention. Among these are their imperviousness, relative inertness, stability at high temperatures, and low coefficients of friction that are relaively unchanging even as the resins are heated. When used as a coating on the tapes of the composite matrices in plate casting machines, neither the tapes nor the coating will adhere to the printing elements even when subjected to the high temperatures generated by the molten metal. Furthermore, the fluorinated synthetic resin being relatively inert and impervious, will prevent any moisture that might be present from attacking the adhesive during the treatments required when forming the printing elements.

The various procedures that may be employed in coating or impregnating a woven base member or in coating a solid base member are known in the art and accordingly a description thereof is not given in the present application except to state that after the base member has been impregnated or coated with the resin, it may be passed through suitable calendcring rolls spaced apart by a distance corresponding to the thickness of the tape desired. In the preferred form of the invention, the coated or impregnated tape is made to a thickness of 0.003 inch.

In order to prepare the polytetrailuoroethylene for the coating of adhesive, one side thereof is etched or activated by conventional means such as by passing the tape into contact with a roller partially submerged in a suitable etching solution.

A pressure sensitive, silicone adhesive 14 is then affixed to the etched side to the tape and this may be done by the same procedure outlined with respect to the etching. The adhesive used in accordance with the teachings of the present invention is a pressure sensitive, solvent containing, silicone based adhesive possessing substantially the same bonding properties at about 400 F. as possessed at room temperature. An example of a suitable adhesive is manufactured by the Dow Corning Corporation under tradename Dow Corning 280 Adhesive. Although in ments.

casting stereotype plates, lthe temperature of the molten lead may range from 550 to 600 F. and tends to lessen the bonding properties of the silicone adhesive, the base member 12 of the tape, as stated above, possesses high thermal insulating qualities and is capable of withstanding much higher temperatures, up to l000 F. with the ECC-11108 woven glass fabric, for example. The base member of the sealing tape therefore acts as an insulating barrier effectively preventing the temperature of the silicone adhesive coating from reaching the point where its bonding properties would be adversely affecte-d.

In the preferred form of the invention, the thickness of the adhesive coating is in the order of 0.003 inch and this results in a preferred tape having an overall thickness of 0.006 inch. Although this is the preferred thickness of the tape used in the present invention, it is of course possible to vary the thickness of the individual parts of the tape as long as the over-all thickness is not so great as to interfere with the patern to be formed on the printing ele- Tapes ranging in thickness from 0.004 to 0.008 inch, for example, are also suitable.

In forming the composite matrix for use in casting machines according to the teachings of the present invention, the primary and one or more secondary matrices are iirst placed in scorching ovens to preshrink each of them to a minimum, substantially fixed size. Next the individual matrices are positioned with the desired edges in abutment either by overlapping, feathering or line contact; or if the secondary matrix is to be inserted within the original border of the primary matrix, they are both cut to the appropriate size and positioned together as shown in FIG. 1. Only after these first two steps have been completed are the tapes 11 placed over the abutting edges of the individual matrices and pressed into sealing engagement therewith. And since the tapes 11, as stated above, are non-shrinkable, a complete bonding, unaected by subsequent heating, may be made between the tapes and the composite matrix. Furthermore, since the individual matrices are preshrunk before the tapes are applied, they may be cut accurately so that their adjacent edges will be in complete abutting relationship in the final composite matrix. With prior conventionally constructed matrices using shrinkable tapes where the tape is shrunk during the scorching operation, it Was not possible to have a final composite matrix wherein the adjacent edges of the individual matrices were in complete abutment with each other since the individual matrices had to be cut, assembled and taped together before the scorching operation and would inherently tend to separate from each other as they were shrunk.

After the tapes have been applied, the composite matrix is then heated to a temperature of about 400 F. for about five minutes or long enough to remove the solvent contained in the silicone adhesive coating. This heating does not cause any further shrinkage of the matrices but is for the purpose of assuring a complete bonding of the tapes to the matrices; and the base member of the tapes themselves being non-shrinkable and capable of withstanding much higher temperatures will not be otherwise affected by this heating. Although the tapes 11 are shown in the drawings as attached to both sides of the composite matrix which is the presently preferred construction, it is of course within the scope of the present invention to apply the tapes to only one side.

After the above operations have been performed, there results a composite matrix particularly suitable for use in forming printing elements. The tapes do not stick to the printing elements as the latter are removed from the matrix nor do they burn or deteriorate or shrink in casting machines to thereby expose the abutting edges of the matrices and allow molten metal to leak between the edges, interfere with the vacuum apparatus and produce unacceptable plates. Furthermore, the polytetrafluoroethylene coating is not affected by moisture and acts to prevent any such moisture from attacking the adhesive.

The sealing of the primary and secondary matrices is so effective that upwards to twenty printing elements of substantially equally high quality can be made from a single composite matrix.

The foregoing describes a preferred form of the composite matrix constructed in accordance with the teachings of the present invention but it is apparent that various changes may be made without departing from the scope of the invention as set forth in the following claims.

We claim:

l. A composite matrix for use in heat generating plate casting machines comprising: an unsupported primary matrix; at least one unsupported secondary matrix positioned adjacent said primary matrix with the adjacent edges of the matrices in abutting, non-interlocking relationship with each other; and a sealing tape, substantially non-shrinking and non-deteriorating at the temperatures generated in the plate catsing machine, covering said abutting edges on at least one side of said primary and secondary matrices in the non-printing area of said mat- Iices, said sealing tape comprising a thermal insulating base member, a fluorinated synthetic resin coating on said base member, and a pressure sensitive, silicone adhesive affixed to one side of the coated base member securely bonding said coated tape to said primary and secondary matrices.

2. A composite matrix according to claim 1 wherein the base member is a woven glass fabric.

3. A composite matrix according to claim 1 wherein the fluorinated synthetic resin is polytetrailuoroethylene.

4. A composite matrix according to claim l wherein the primary and secondary matrices are substantially moisture free.

5. A composite matrix for use in stereotype plate casting machines generating temperatures of between about 550 F. and 600 F. comprising: an unsupported primary martix; at least oneunsupported secondary matrix positioned adjacent said primary matrix with the adjacent edges of the matrices in abutting, non-interlocking relationship with each other, said primary and secondary matrices being substantially free of moisture; and a sealing tape, substantially non-shrinking and non-deteriorating at the temperatures generated in the plate casting machine, covering said abutting edges on at least one side of said primary and secondary matrices in the non-printing areas of said matrices, said sealing tape comprising a thermal insulating base member of woven glass fabric, a polytetrafluoroethylene coating on said base member, and a pressure sensitive silicone adhesive affixed to one side of the coated base member securely bonding said coated tape to said primary and secondary matrices, said adhesi-ve possessing substantially the same bonding properties at about 400 F. as possessed at 70 F.

6. A composite matrix according vto claim 5 wherein the width of said tape is about 0.75 inch, the thickness of said glass fabric coated with said polytetrafluoroethylene is about 0.003 inch and the total thickness of said tape is about 0.006 inch.

7. The method of forming a composite matrix having an unsupported primary and at least one unsupported secondary matrix attached together for use in heat generating plate casting machines comp-rising the steps of heating the primary and secondary matrices to temperatures sufficient to remove substantially all moisture therefrom; positioning the secondary matrix adjacent said primary matrix with the adjacent edges of the matrices in abutting, non-interlocking relationship with each other; placing over said abutting edges on at least one side of the primary and secondary matrices in the non-printing areas thereof, a sealing tape which is substantially nonshrinking and non-deteriorating at the temperatures generated in the plate casting machine and comprised of a base member of thermal insulating material, a fluorinated synthetic resin coating on said base member, and a silicone adhesive affixed to the coated side of said base member adjacent said matrices; and adhering said sealing tape to said primary and secondary matrices.

8. The method of forming a composite matrix having ,an unsupported primary and at least one unsupported secondary matrix attached together for use in heat generating plate casting machines comprising the steps of heating the primary and secondary matrices to temperatures suicient to remove substantially all moisture therefrom; positioning each secondary matrix adjacent said primary matrix with the adjacent edges of the matrices in abutting, non-interlocking relationship with each other; placing over said abutting edges on at least one side of the primary and secondary matrices in the non-printing areas thereof, a sealing tape which is substantially nonshiinking and non-deteriorating at the temperatures generated in the plate casting machine and comprised of a base member of woven glass fabric, a coating of polytetrauoroethylene on said base member, and a silicone adhesive aixed to the coated side of said base member adjacent said matrices; and adhering said sealing tape to said primary and secondary matrices.

9. The method of forming a composite matn'x having an unsupported primary and at least one unsupported secondary matrix attached together for use in stereotype plate casting machines generating temperatures of between about 550 F. and 600 F. comprising the steps of heating the primary and secondary matrices to temperatures suicient to remove substantially all moisture therefrom; positioning each secondary matrix adjacent said primary matrix with the adjacent edges of the matrices in abutting, non-interlocking relationship with each other; placing over said abutting edges on at least one side of the primary and secondary matrices in the non-printing areas thereof, a sealing tape which is substantially non-shrinking and non-deteriorating at said temperatures generated in said plate casting machine and comprised of a base member of Woven glass fabric, a coating of polytetrafluoroethylene en said base member, and a pressure sensitive, silicone adhesive possessing substantially the same bonding properties at 400 F. as possessed at 70 F. aixed to the side of said coated base member adjacent said matrices; and applying pressure tov said sealing tape to cause it to adhere to said primary and secondary matrices.

References Cited by the Examiner UNUSED STATES PATENTS Re. 10,385 9/83 Dement.

2,702,927 3/ 55 Travis 101-401.2 2,946,710 7 60 Fields. 3,067,078 12/ 62 Gluck. 3,075,261 1/ 63 White.

DAVID KLEIN, Primary Examiner.

WILLAM B. PENN, Examiner,

UNITED STATES PATENT oFFICE CERTIFICATE OF CORRECTION Patent No. 3,181,206 May 4, 1965 Edward D. Hagney et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 8, for "orifice" read orifices column 4, line 13, for "polytetrafluorethylene" read polytetrafluoroethylene line 14, for "silicon" read silicone line 41, for "relatively" read relatively column 5, line 2, for "tends" read tend line 19, for

"patern" read pattern column 6, line 18, for "catsing" read Casting Signed and sealed this 5th day of October 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims (1)

1. A COMPOSITE MATRIX FOR USE IN HEAT GENERATING PLATE CASTING MACHINES COMPRISING: AN UNSUPPORTED PRIMARY MATRIX; AT LEAST ONE UNSUPPORTED SECONDARY MATRIX POSITIONED ADJACENT SAID PRIMARY MATRIX WITH THE ADJACENT EDGES OF THE MATRICES IN ABUTTING, NON-INTERLOCKING RELATIONSHIP WITH EACH OTHER; AND A SEALING TAPE, SUBSTANTIALLY NON-SHRINKING AND NON-DETERIORATING AT THE TEMPERATURES GENERATED IN THE PLATE CASTING MACHINE, COVERING SAID ABUTTING EDGES ON AT LEAST ONE SIDE OF SAID PRIMARY AND SECONDARY MATRICES IN THE NON-PRINTING AREA OF SAID MAT-

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