US3151548A - Duplicating stencils - Google Patents

Duplicating stencils Download PDF

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Publication number
US3151548A
US3151548A US360056A US36005664A US3151548A US 3151548 A US3151548 A US 3151548A US 360056 A US360056 A US 360056A US 36005664 A US36005664 A US 36005664A US 3151548 A US3151548 A US 3151548A
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United States
Prior art keywords
stencil
paper
sheet
conductive layer
backing sheet
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Expired - Lifetime
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US360056A
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English (en)
Inventor
Picking Henry John
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NRG Manufacturing Ltd
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NRG Manufacturing Ltd
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
    • B41N1/00—Printing plates or foils; Materials therefor
    • B41N1/24—Stencils; Stencil materials; Carriers therefor
    • B41N1/246—Stencils; Stencil materials; Carriers therefor characterised by the electroconductive means or additives

Definitions

  • One known type of stencil adapted to be cut electrically comprises a paper backing coated with a highly conductive carbon-containing layer and a stencil sheet of thin porous paper (the stencil tissue used in conventional typing stencils) impregnated with nitrocellulose loaded with carbon to give an electrically conductive layer of lower conductance than the aforesaid highly conductive layer, the stencil sheet being mounted on the same side of the backing as the highly conductive layer.
  • a further disadvantage of this type of stencil is the extent to which set oif (transfer of ink from one recently duplicated copy to the back of the next) occurs.
  • Another known type of electrica ly cut stencil comprises a paper backing having a double layer of a vinyl chloride polymer film strippably bonded thereto, both layers of polymer film being loaded with carbon to render them electrically conductive, that adjacent the backing having (as in the first type of stencil) the higher conductivity.
  • the double film is perforated electrically and then stripped from the backing.
  • This type of stencil requires expensive equipment to cast the very thin selfsupporting vinyl chloride polymer films needed.
  • the film is liable to tear on stripping and inevitably shrinks after the stripping operation.
  • a further disadvantage is that used stencils of this type have to be stored in such a way as to prevent loss of plasticiser if further shrinkage and tendering are to be avoided.
  • the present invention provides a novel type of electrically cut duplicating stencil free from the disadvantages inherent in the types of stencil mentioned above.
  • the duplicating stencil of the present invention comprises a backing sheet having attached thereto a stencil sheet made of paper less than 0.00125 inch thick (which can be wet strengthened) of porosity not greater than 250 (determined by the Gurley-Hill SPS method), and loaded with particles of an electrically conductive material, and coated on the side adjacent the backing sheet with a highly conductive layer capable of being cut electrically and having a conductivity of 4 l0 to 2 l0*' mhos, when determined by the method hereinafter described, and on the opposite side with a relatively less conductive layer also capable of being cut electrically.
  • the backing sheet can be of the kind ordinarily used on duplicating stencils and will normally be attached to the stencil sheet along one edge provided with perforatic-as or other means for attaching the stencil to the duplicating machine.
  • a scored line near this edge enables the backing sheet to be easily torn away from the stencil sheet when the latter is in position on the duplicating machine.
  • the backing sheet will ordinarily be white or pale-coloured.
  • a lithographic master sheet having a hydrophilic surface If this is done then, during the cutting of the stencil, material is transferred from the cut Patented Get.
  • the lithographic master sheet may be of paper or metal or of other conventional kind.
  • the paper used in the stencil sheet must be thin and of very low porosity. If it is too thick it cannot be satisfactorily cut electronically. A practical maximum thickness is 0.00125 in., and a thickness of about 0.001 inch is preferred. if it is too porous, there is liable to be some irregular interpenetration of the two conductive layers and the desirable properties of the new stencil will be marred or lost.
  • the maximum porosity is 250 as determined by the Gurley-Hill SPS method. This method is based on a determination of the time in seconds taken for cc. of air to penetrate the paper under standard conditions. It will be noted that a high figure corresponds to a low porosity and vice versa.
  • a paper having a maximum porosity of 250 has a porosity which numerically has a minimum value of 250.
  • the preferred porosity is about 1500.
  • the weight of the paper will ordinarily be governed by the need to satisfy the necessary conditions of thickness and porosity.
  • a paper weighing about 10-12 g./rn. gives good results.
  • the thin, non-porous paper is preferably wet-strengt ened so as to make the stencil capable of enduring long runs on the duplicator.
  • any synthetic resin useful for wetstrengthening paper e.g. ureaand melamine-formaldehyde resins, but resins such as polyamides, water insolubilisable polyacrylates and acrylate copolymers, polyacrylic esters (e.g. polymethyl methacrylate), polystyrene and its copolymers, and natural and synthetic elastomers are preferred because they ha a no deleterious effect on the electrical properties of the paper.
  • the resins are incorporated in the paper during its manufacture as aqueous dispersion, emulsions (latices) or solutions. If the resin is initially water-soluble, it must be rendered insoluble in situ in the paper.
  • the particularly preferred resin is a polyamide modified with an epihalohydrin, e.g. that sold under the trade name Kymene 660 by the Hercules Powder Company, which is the product obtained by condensing a polyamide with epichlorohydrin so that the secondary amino groups react with the formation of an azidine ring (see United States Patent No. 2,926,154).
  • the paper is loaded with electrically conductive particles by adding the latter as a paste to the paper-making pulp in the beater. From 5% up to about 30% by weight of the paper of the conductive particles may be added, about 10% being preferred. Particles of carbon black are preferably used but metal powders are also operable, the concentration of particles depending on their particular electrical conductivity.
  • the highly conductive layer capable of being cut electrically may be a layer of highly conductive particles, e.g. of carbon black, dispersed in a film-forming binder, which is, if necessary, plasticized.
  • a film-forming binder which is, if necessary, plasticized.
  • Polyvinyl chloride copolymer is preferred but cellulose nitrate, polyvinyl formal, polyvinyl acetate copolymers, polymethyl meth acrylate and its copolymers can, for example, all be used.
  • the layer of lower electrical conductivity is similar in composition to the highly conductive layer except that its conductivity is reduced by using either less of the conductive particles or particles of lower intrinsic conductivity, or both.
  • the conductivity of the highly conductive layer is 4X10 to 2 1O- mhos, preferably 4 10 to 1 10 mhos, as determined using two brass electrodesone cm. apart, each 1 cm. square and under a load of 2 kilograms.
  • the conductivities of the paper and the less conductive layer are not critical but are ordinarily much lower than that of the highly conductive layer.
  • the paper has a conductivity, measured in the same Way as that mentioned above but on paper having the highly conductive layer on the reverse side, which is usually 1.6 10* to 2 l0 mhos or even lower, preferably 1 10- to 6X10 mhos.
  • the layer of lower conductivity has a conductivity, measured in the same way on a complete stencil sheet, i.e.
  • both paper and highly conductive layer which is less than that of the paper and is ordinarily 1.4 10 to 2 10- mhos and is preferably 6x10- to 5 10 mhos. It should be borne in mind that it may sometimes be desirable to'vary the conductance of the upper layer (that of lower conductivity) so as to match the output of the electronic scanning device used to cut the stencil. The figures given however suit the type of machine most commonly in use.
  • the two conductive layers are conveniently coated on the base paper by dispersing the coating composition in a solvent for the binder, for example acetone when the binder is polyvinyl chloride, and applying the dispersion to the paper by a known coating method, egg. by roller coating or slot coating.
  • a solvent for the binder for example acetone when the binder is polyvinyl chloride
  • An advantage of the new type of stencil is that it can be made using the same coating and other machinery used formaking conventional, mechanically-cut stencils. Expensive equipment is not required as the coated layers do not have to be self-supporting.
  • the two conductive layers together should not be more than 0.0005 in. thick so that the total thickness of stencil should not exceed 0.00175 in. 1
  • the new stencils possess the advantage that their use involves little or no set ofi during duplication. This is due to the fact that the new stencils can be made very thin, and thinner, for example, than prior known stencils based on stencil tissue, and
  • the upper surface of the stencil may be provided with a white or grey top coat to render the characters on the cut stencil more visible.
  • a white or grey top coat may have acomposition similar to those of the conductive layers and be applied in a similar way, except that the carbon is replaced by a white or grey pigment, e.g. titanium dioxide. While these top coats have the advantage mentioned, they are liable to be a source of wastage in manufacture and the preferred stencils therefore do not include them.
  • the new stencils have a property which is sometimes advantageous,,narnely that they can be cut mechanically, e.g. with a wheel pen or with a file plate and stylus. This makes it possible to cut the new stencils partly electrically and partly mechanically, so that, for example, additions may be made to a sheet being copied.
  • Example The stencil sheet is tissue weighing 11 g./sq. rn., having (on evaporation of the acetone) a highly conductive layer.
  • a stencil according to claim 1 in which the stencil sheet is made of paper about 0.001 inch thick and having a porosity of about 1500 determined by the Gurley-Hill SPS method.
  • a stencil according to claim 1 in which the stencil sheet is made of paper loaded with 5 to 30% by weight of electrically conductive particles.
  • a stencil according to claim 1 in which the highly conductive layer and the relatively less conductive layer are layers of a film-forming binder having electrically con ductive particles dispersed therein.
  • a stencil according to claim 8 in which the said layers are layers of polyvinyl chloride having carbon black dismrsed therein.
  • a stencil according to claim 9 in which the combined thickness of the inch.
  • A'stencil according to claim 1 provided with a pale coloured top coat.
  • a stencil according to claim 1 provided with a.
  • lithographic master having a hydrophilic surface adjacent to the stencil sheet'on the side next to the backing sheet.
  • a duplicating stencil comprising a backing sheet, a
  • said layers is not more than 0.0005
  • a duplicating stencil comprising a backing sheet, a stencil attached to said backing sheet and made of paper about 0.001 inch thick, wet-strengthened with an epihalohydrin-modified polyamide, having a porosity of about 1500 determined by the Gurley-Hill SPS method, loaded with 5 to 30% by weight of carbon black particles and having a conductivity of 1 l0- to 6 10- mhos, a highly conductive layer of a polyvinyl chloride binder having carbon black particles dispersed therein and having a conductivity of 4X 10 to 1X10 mhos coated on said paper on the side adjacent said backing sheet, and a relatively less conductive layer of a polyvinyl chloride binder having carbon black particles dispersed therein and having a conductivity of 6 10-' to 5 10 mhos, coated on said paper on the opposite side to said backing sheet, the combined thickness of the said layers being less than 0.0005 inch thick.

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  • Printing Plates And Materials Therefor (AREA)
US360056A 1963-04-29 1964-04-15 Duplicating stencils Expired - Lifetime US3151548A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB16835/63A GB1003612A (en) 1963-04-29 1963-04-29 Improvements in or relating to duplicating stencil blanks

Publications (1)

Publication Number Publication Date
US3151548A true US3151548A (en) 1964-10-06

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ID=10084530

Family Applications (1)

Application Number Title Priority Date Filing Date
US360056A Expired - Lifetime US3151548A (en) 1963-04-29 1964-04-15 Duplicating stencils

Country Status (8)

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US (1) US3151548A (de)
AT (1) AT252963B (de)
BE (1) BE646919A (de)
CH (1) CH433406A (de)
DE (1) DE1251775B (de)
DK (1) DK112592B (de)
GB (1) GB1003612A (de)
NL (1) NL6404557A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3376162A (en) * 1964-11-23 1968-04-02 Gestetner Ltd Electrographic transfer sheet
US3376810A (en) * 1963-06-21 1968-04-09 Gestetner Ltd Duplicating stencils
US3891786A (en) * 1973-10-05 1975-06-24 Herculite Protective Fab Electrically conductive sheeting
US6138561A (en) * 1996-09-13 2000-10-31 Watanabe; Hideo Composition and method for perforating heat-sensitive stencil sheet
US6593001B1 (en) * 1995-10-05 2003-07-15 Riso Kagaku Corporation Method for perforating heat-sensitive stencil sheet and stencil sheet

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0664360A (ja) * 1992-08-19 1994-03-08 Riso Kagaku Corp 孔版印刷用原紙の製法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528005A (en) * 1948-05-14 1950-10-31 Western Union Telegraph Co Electrosensitive recording blank
DE1055558B (de) * 1956-07-06 1959-04-23 Zeuthen & Aagaard As Elektro-Rohmatrizen und Verfahren zu ihrer Herstellung
US3113511A (en) * 1961-02-27 1963-12-10 Harold R Dalton Composite stencil-offset printing blank

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528005A (en) * 1948-05-14 1950-10-31 Western Union Telegraph Co Electrosensitive recording blank
DE1055558B (de) * 1956-07-06 1959-04-23 Zeuthen & Aagaard As Elektro-Rohmatrizen und Verfahren zu ihrer Herstellung
US3113511A (en) * 1961-02-27 1963-12-10 Harold R Dalton Composite stencil-offset printing blank

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3376810A (en) * 1963-06-21 1968-04-09 Gestetner Ltd Duplicating stencils
US3376162A (en) * 1964-11-23 1968-04-02 Gestetner Ltd Electrographic transfer sheet
US3891786A (en) * 1973-10-05 1975-06-24 Herculite Protective Fab Electrically conductive sheeting
US6593001B1 (en) * 1995-10-05 2003-07-15 Riso Kagaku Corporation Method for perforating heat-sensitive stencil sheet and stencil sheet
US6138561A (en) * 1996-09-13 2000-10-31 Watanabe; Hideo Composition and method for perforating heat-sensitive stencil sheet

Also Published As

Publication number Publication date
NL6404557A (de) 1964-10-30
DK112592B (da) 1968-12-30
GB1003612A (en) 1965-09-08
BE646919A (de) 1964-10-22
DE1251775B (de)
AT252963B (de) 1967-03-10
CH433406A (de) 1967-04-15

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