US3267847A

US3267847A - Method of preparing stencils for use in stencil duplicating

Info

Publication number: US3267847A
Application number: US387098A
Authority: US
Inventors: Hayama Noborn; Ishijima Kazuo
Original assignee: Riso Kagaku Corp
Current assignee: Riso Kagaku Corp
Priority date: 1963-08-03
Filing date: 1964-08-03
Publication date: 1966-08-23
Anticipated expiration: 1983-08-23
Also published as: DE1496168C3; GB1059553A; DE1496168B2; DE1496168A1

Description

1956 NOBORU. HAYAMA ETAL. 3,267,847

METHOD OF PREPARING STENCILS FOR USE IN STENCIL DUPLICATING Filed Aug. 5. 1964 FIG.'4

hm W INVE TOR:

BY W

United States Patent 3,267,847 METHOD OF PREPARING STENCILS FOR USE IN fiTENClL DUPLICATING Nohoru Hayama and Kazuo Ishijima, Tokyo, Japan, assignors to Riso Kagaku Corporation, Tokyo, Japan, a corporation of Japan Filed Aug. 3, 1964, Ser. No. 387,098 Ciairns priority, application Japan, Aug. 3, 1963, 38/ 41,499, 38/415410; Aug. 19, 1963, 38/ 43,395 4 Claims. (Cl. 101-1282) This invention relates to stencil duplicating techniques and more particularly to a novel method of preparing stencils wherein stencil sheets are perforated by utilizing radiant rays.

In the conventional stencil duplicating technique desired characters, figures and patterns are perforated by writing the contents of manuscripts with a burin upon Waxed stencil papers which are placed on flat files. Alternatively these contents of manuscripts are type written upon stencil papers having a plastic film thereon. Both of these prior art methodsrequire many times, labours and skilled operators. While there has been proposed another method of perforation which utilizes photosensitive stencil sheets, this method has many defects that it must be carried out in dark rooms, and can not be perforated unless developed by a process similar to that of ordinary photograph art which requires troublesome procedure of treating the stencil papers with a solvent. In addition, the resulted stencil sheet has poor storage ability. Still another approach of perforating stencil sheets is to use spark discharge but this method not only requires long working time but also necessitates to use expensive stencil papers and perforating apparatus of com plicated construction which, of course, is liable to get out of order.

It is an object of this invention to eliminate various defects mentioned above and to provide a novel method of perforating desired characters, figures, codes, patterns, photographs or the like through stencil sheets in a short time and with less effort at high efiicien-cy.

A further object of this invention is to provide a new and improved method of easily perforating stencil sheets without any skil but by using simple apparatus.

Still further object of this invention is to provide stencils capable of providing clear stencil duplications.

Another object of this invention is to provide a method of perforating a novel stencil sheet upon which characters, figures or patterns can be printed by stencil duplicating process.

Yet another object of this invention is to provide a novel method of easily perforating characters, figures or patterns which are identical with those contained in manuscripts.

A still further object of this invention is to provide a novel method wherein characters, figures or patterns are presented directly upon the surfaces of stencil sheets and then perforated by simple means.

Further objects and advantages of this invention, may best be understood by referring to the following description taken in connection with the drawing.

It is to be understood that the term stencil duplication used herein not only includes conventional method of printing by using rotary presses or hand presses wherein printing is effected by printing ink which penetrates through perforations of stencil sheets but also broadly covers various methods of printing (or sometimes called as method of duplicating) which utilize perforations through stencil sheets representing characters, figures, patterns or the like, such as a method wherein adhesive powders are deposited upon sheet materials to be printed such as papers after passing through perforations of stenoil sheets, a method wherein colored stencil sheets are utilized together with diazo photosensitive papers, blue print sensitive papers and the like methods.

In addition to common characters, figures, patterns and combinations thereof, it is also intended to cover codes, photographs, pictures and combinations thereof by the terms, characters, figures and patterns used herein.

Further it is to be understood that by the term stencil sheet used herein is meant to designate a material from which stencils are manufactured for carrying out said stencil duplicating process so that it should be interpreted in broader sense to include such materials which differ substantially from well known stencil paper for preparing stencils in contents, appearance, and material.

Briefly stated, this invention contemplates to provide a method of preparing stencils for use in stencil duplication characterized by irradiating radiations onto a heat sensitive stencil sheet which is superposed upon a manuscript containing requisite characters, figures or patterns or onto a heat sensitive stencil sheet upon which the characters and the like are directly represented, and causing said stencil sheet to respond to heat generated by said characters, figures or patterns by absorbing said radiations so as to provide perforations through said stencil sheet which are nearly identical with said characters, figures or patterns.

The following specific examples of this invention are given by referring to the accompanying drawings, in which FIG. 1 is a transversal sectional view of an apparatus suitable to be utilized in carrying out this method;

FIG. 2 is an enlarged perspective view of a portion of a stencil sheet utilized in this invention;

FIG. 3 is an enlarged perspective view of a portion of another stencil sheet utilized in this invention; and

FIG. 4 is an enlarged perspective view with one part broken away, of a portion of still another stencil sheet utilized in this invention.

Referring now to the accompanying drawing, there is shown in FIG. 1 a box like platform 11 to support a perforating apparatus (not shown) containing an elongated tubular infrared ray lamp 12 which is adjustable for horizontal movements by means provided outside of the platform 11. A glass plate 13 transparent to infrared rays is fit in the upper opening of the platform 11 to support a silk screen of about 50 to meshes.

A stencil sheet 15 as shown in FIGS. 2 to 4 inclusive is tinted with a color that exhibits poor absorption to infrared rays or transparent to such rays.

FIG. 2 shows the simplest form of the stencil sheet comprising a single layer of heat shrinkable film, having a thickness of about 15 microns, such as stretched polypropylene resin film and a film of copolymer of vinylidene chloride and vinyl chloride.

FIG. 3 shows a modified stencil sheet which was prepared by mixing heat shrinkable resinous fibers 21 such as nylon or polyethylene resin fibers and base fibers 22 which do not shrink at temperatures at which shrinkage of said resinous fiber 21 occurs, such as fibers used as a raw material for making Japanese papers, in the ratio of 40% of the former and 60% of the latter, by weight, and then shaping them into papers having a thickness of about 50 microns. As the heat shrinkable resinous fiber, polypropylene fibers, and fibers prepared from a copolymer of vinylidene chloride and vinyl chloride may be used in addition to polyethylene fibers mentioned above. Also in addition to the above mentioned fibers, long fibers of manila hemp, asbestos fibers, glass fibers and the like may be used as the base fibers. Further said base fibers may be embedded in heat shrinkable resinous material to form a sheet.

A modified stencil sheet illustrated in FIG. 4 comprises a film of said heat shrinkable resin 23 and a porous supporting sheet 24 cemented thereto which does not change its state at said shrinking temperatures. While the supporting sheet 24 may be bonded to the heat shrinkable resinous film 23 by means of heating or adhesive material, when using adhesive material it should be applied as a film having a thickness as small as possible. When a copolymer of vinylidene chloride and vinyl chloride sold under the trade name of Saran film is used as the heat shrinkable resinous film 23 and tengujo paper (Japanese coarse tissue paper) as the supporting sheet it is advantageous to make the thickness of the former to be about microns and that of the latter about microns. As the heat shrinkable resinous film, may be used polyethylene and polyester resin film while as the supporting sheet may be used pulp, woven fabric, non-woven fabric, fine meshed screen not sensitive to heat and the like.

In carrying out this invention, as shown in FIG. 1 a manuscript 16 is placed upon the stencil sheet 15 and then a disc 17 of elastic material formed with a reflective surface on its lower surface or a lower surface of a color having poor absorption property towards infrared rays is superposed upon the manuscript, a portion of the periphery of said disc 17 being clamped to the platform 11 to firmly hold the stencil sheet 15 against the manuscript. The stencil sheet shown in FIG. 1 is of the type that has been described in connection with FIG. 3. The manuscript employed is of the ordinary type that contains the matter to be reproduced such as black characters, figures or patterns which are written on a white paper. Any type of type written or hand written manuscript could be used so long as characters, figures or patterns are written or printed on a sheet of a color having 'poor absorption property towards infrared rays with an ink of a color having good absorption property towards infrared rays.

After assembling, the ultrared ray lamp 12 is lighted and is then moved horizontally from one side to the other of the platform 11 to irradiate both of the stencil sheet 15 and the manuscript 16 through the screen 14, In this case, care should be taken to move the infrared ray lamp 12 at a relatively high speed of about 3 to 6 cm./sec. to irradiate for a relatively short interval of time so that the temperature of the portions of the stencil 'sheet 15 corresponding to the characters, figures or patterns represented on the manuscript 16 can rise to about 170 C. Under such condition, as the light source is moved, the whole irradiated surface of the stencil sheet 15 will successively receive the infrared rays as well as radiant heat emanated from the infrared ray lamp to cause heat shrinkage of the first stage. Simultaneously therewith, the portions of the stencil sheet 15 corresponding to the characters, figures or patterns represented on the manuscript will be heated stronger than the remaining portions due to their high absorption of infrared rays. As a consequence portions that correspond to characters, figures or patterns on the manuscript 16 will fuse and decompose partially, this in conjunction with the said shrinkage of the whole irradiated surface of the manuscript will make perforations of substantially identical configurations as those of the characters, figures or patterns on the manuscript.

Perforations thus formed tovrepresent the characters, figures or patterns are in the form of an asembly of small perforations which are reinforced by a grid structure comprising portions of the stencil sheet remaining unfused due to the shielding action of the screen 14 against infrared rays. As a result, even when the areas of the characters, figures or the patterns are too large, breakage of the stencil paper could be prevented effectively. In addition, during printing operation, too much penetration of the printing ink can also be effectively precluded.

It is to be understood that it is not always necessary to use a screen in the perforating apparatus when a stencil paper shown in FIG. 3 or 4 is utilized. With such a stencil sheet the supporting fiber or the supporting sheet will remain in the portions which have been perforated to effectively prevent breakage of the stencil sheet and excessive penetration of the printing ink. Stencil sheets including such supporting member as supporting fibers or supporting sheet have large mechanical strength even after perforation so that they can be handled easily because such supporting member does not undergo thermal change. Where use is made of a stencil sheet comprising a heat shrinkable resinous film and a supporting sheet which are bonded together by means of a binder the thin film of the binder is also perforated simultaneously with the heat shrinkable resinous film.

Upon completion of perforation the stencil sheet is removed from the platform together with the manuscript and is then separated therefrom. Thereafter the completed stencil can be used in a hand or rotary printing press to print with a printing ink in the same way as the stencils that have been perforated by the well known method.

While in the preceding description the invention has been stated to use a manuscript, it should be understood that this invention is by no means limited to the use of manuscripts. Thus, instead of superposing a stencil sheet and a manuscript the matter to be reproduced such as, characters, figures or patterns may be directly typewritten or hand written on the surface of a stencil sheet with an ink or pencil or a color having high absorption towards infrared rays. Alternatively, powders which have high infrared ray absorption and can be easily converted by heat may be directly deposited on the surface of the stencil by the electronic photograph technique to represent characters and the like.

The heat shrinkable resinous film utilized in the stencil papers shown in FIGS. 2 and 4 is made of a film of a copolymer of vinylidene chloride and vinyl chloride which has been subjected to stretching treatment (generally termed as infiation process). However, if the heat shrinkability'of the film'is to large, the resolution thereof will become excessive so that the reproduced characters and the like would not be clear. Thus, it is advantageous to increase the resolution of the stencil after perforation by subjecting it to a slight heat shrinkage treatment whereby to suitably adjust its remaining heat shrinkability. It is desirable to adjust this remaining shrinkability such that the stencil paper will shrink by about 2 to 3 mm., both longitudinally and transversally, when a test piece of the stencil sheet, 20 cm. x 20 cm., is irradiated by an infrared ray lamp .at a rate of 3 to 4 cm./sec. in a perforating machine shown in FIG. 1 in a manner similar to perforation of a stencil sheet by utilizing a manuscript. This pretreatment can also be applied to the stencil paper shown in FIG. 3.

There are four pretreatment processes as follows:

(1) To move said film, under slight tension and under no pressure, to pass closely around the surfaces of several metallic heated rolls. The temperature of the rolls is varied from about 60 C. at the first roll to about 100 C. at the final roll, and the speed of the film is selected to be about 15 to 30 m./sec.

(2) To pass the film through a bath of hot water at a speed such that it will be dipped in the bath for about 17 seconds.

(3) To hold a rolled film in a constant temperature room, a vapor bath room or in a warm water, respectively maintained at 50 C. to C., for 5 to 10 hours.

(4) To move the film, under no pressure and under a slight tension, at a speed of about 5 to 25 cm./sec., through an infrared ray heating room which is preheated to about 80 C.

Usually the weight ratio between vinylidene chloride and vinyl chloride comprising a heat shrinkable film for stencil papers is about 80% :20%. However by changing this ratio to'81 to %:19 to 5%, or by increasing the percentage of vinylidene chloride content clear and sharp perforations can be produced. By increasing the content of vinylidene chloride beyond 84% results in the same excellent resolution as that of the pretreated stencil paper.

It is also contemplated to use other radiations such as high frequency electromagnetic waves, radiations emanated from radio isotopes and the like in addition to infrared ra s.

There are two methods of irradiation as follows:

In one case wherein a stencil paper with characters and the like are directly represented thereon is to be perforated, irradition may be given to either side of the stencil paper.

In the other case wherein a manuscript is used and the stencil sheet is to be perforated according to the contents of the manuscript, the surface of the manuscript and the heat sensitive surface of the stencil paper should be intimately contacted. Opposite surfaces of stencil sheets shown in FIGS. 2 and 3 are physically the same so that either one of these surfaces can be closely contacted with the manuscript. In this case, an assembly of the stencil sheet and the manuscript which are superposed in intimate contact relation is subjected to irradiation. If the manuscript is rather thick so that radiations tare difiicult to pass through it, the irradiation should be made from the side of the manuscript whereas if the manuscript is rather thin to permit radiations to pass easily therethrough, and if characters and the like are represented on only one side of the manuscript, then irradiation may be made either from the side of the manuscript or the side of the stencil paper.

Even if thin manuscripts are employed, as they usually contain characters and the like on both sides thereof, irradiations must be made from the side of the stencil paper in order to perforate it.

It should be understood that stencils which have been perforated in accordance with the method of this invention can be utilized not only in a method of printing which utilizes a printing ink, but also in various other methods of printing including a perforated stencil printing method wherein solid particles are transferred to and deposited on a printing paper through perforations in the stencil and a method wherein a stencil paper tinted with red color and hence is opaque to ultraviolet rays is utilized to print on a paper by means of diazo photosensitive system by permitting ultraviolet rays to pass only through perforations.

While in the above embodiments an infrared ray lamp was moved with respect to a fixed stencil paper but it will be clear to those skilled in the art that the stencil or a compact assembly of a stencil and a manuscript may be moved with respect to the source of radiation. It will also be understood that an infrared spot light source may be utilized as the source of irradiation. More particularly, in this case infrared ray irradiation can be made while'holding stationary both of the ligth source and a stencil paper with characters, figures or patterns directly represented thereon, and also a manuscript when it is used.

In order to provide intimate contact between a stencil sheet and a manuscript, air may be used or they may be urged against a support by tension, as has been the practice in the prior art.

While the invention has been explained by describing particular embodiments thereof, it will be apparent that improvements and modifications may be made without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. A method of preparing a stencil sheet for use in reproducing black master material comprising the steps of heat stretching a stencil sheet having thereon a heat shrinkable fihn of a copolymer of vinylidene chloride and vinyl chloride to the extent that said sheet will shrink between about two to three millimeters for a sheet of about twenty centimeters square, superposing said sheet upon the material to be reproduced, irradiating said stretched sheet with infrared rays from a lamp moving at between about three to six centimeters per second across the sheet so as to perforate the sheet, the shape of the perforations corresponding to the master material to be reproduced.

2. The method according to claim 1 wherein the Weight ratio between vinylidine chloride and vinyl chloride is about parts of vinylidine chloride and 20 parts of vinyl chloride.

3. The method according to claim 2 wherein ratio of vinylidine chloride to vinyl chloride is about parts to 5 parts.

4. The method according to claim 3 wherein a porous supporting medium, not affected by the action of the heat thereon is bonded to said sheet.

References Cited by the Examiner UNITED STATES PATENTS 1,456,794 5/1923 Gestetner 101--l28.3 2,699,113 l/1955 Hoover 10ll28.4 2,808,777 10/1957 Roshkind 101128.2

DAVID KLEIN, Primary Examiner.

Claims

1. A METHOD OF PREPARING A STENCIL SHEET FOR USE IN REPRODUCING BLACK MASTER MATERIAL COMPRISING THE STEPS OF HEAT STRETCHING A STENCIL SHEET HAVING THEREON A HEAT SHRINKABLE FILM OF A COPOLYMER OF VINYLIDENE CHLORIDE AND VINYL CHLORIDE TO THE EXTENT THAT SAID SHEET WILL SHRINK BETWEEN ABOUT TWO TO THREE MILLIMETERS FOR A SHEET OF ABOUT TWENTY CENTIMETERS SQUARE, SUPERPOSING SAID SHEET UPON THE MATERIAL TO BE REPRODUCED, IRRADIATING SAID STRETCHED SHEET WITH INFRARED RAYS FROM A LAMP MOVING AT BETWEEN ABOUT THREE TO SIX CENTIMETERS PER SECOND ACROSS THE SHEET SO AS TO PERFORATE THE SHEET, THE SHAPE OF THE PERFORATIONS CORRESPONDNG TO THE MASTER MATERIAL TO BE REPRODUCED.