CA1040424A - Heat-sensitive stencil sheet - Google Patents
Heat-sensitive stencil sheetInfo
- Publication number
- CA1040424A CA1040424A CA094,218A CA94218A CA1040424A CA 1040424 A CA1040424 A CA 1040424A CA 94218 A CA94218 A CA 94218A CA 1040424 A CA1040424 A CA 1040424A
- Authority
- CA
- Canada
- Prior art keywords
- film
- heat
- stencil sheet
- sensitive stencil
- range
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- B41N1/242—Backing sheets; Top sheets; Intercalated sheets, e.g. cushion sheets; Release layers or coatings; Means to obtain a contrasting image, e.g. with a carbon sheet or coating
Landscapes
- Printing Plates And Materials Therefor (AREA)
- Laminated Bodies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A heat-sensitive stencil sheet comprising a thin porous supporting sheet having bonded thereon a heat shrinkable thermoplastic film and a thin layer consisting substantially of a releasing agent selected from the group consisting of silicone resins, said layer being formed by coating said agent onto a surface of said film, whereby the stencil sheet is rendered releasable with respect to an original at the time of making a stencil.
A heat-sensitive stencil sheet comprising a thin porous supporting sheet having bonded thereon a heat shrinkable thermoplastic film and a thin layer consisting substantially of a releasing agent selected from the group consisting of silicone resins, said layer being formed by coating said agent onto a surface of said film, whereby the stencil sheet is rendered releasable with respect to an original at the time of making a stencil.
Description
104~)424 BACKGROUND OF THE INVENTION
a) Field of the Invention The present invention relates to a stencil sheet which comprises a thin porous supporting sheet having bonded thereon a heat shrinkable synthetic resin film and is further provided with releasable property or heat-fusion preventability.
b) Description of the Prior Art A stencil for use in mimeographic printing can be readily prepared by employing a heat-sensitive stencil sheet comprising a porous 10 thin paper weighing about 8~V15 gm. per square meter, i. e. a porous supporting sheet consisting mainly of natural fiber obtained from mitsumata, paper mulberry, manila hemp, etc. or synthetic fiber cansisting of rayon, vinylon, tetron, acrylic fiber or the like and provided with a heat shrinkable thermoplastic film bonded thereon, such as, for instance, a film compris-~g vinylidene chloride-vinyl chloride copolymer. On this occasion, said ~tencil for use in mimeographic printing i9 obtained through the following processes: an original i9 brought into close contact with the film-bonded ~, ~urface of the foregoing stencil sheet; the back of the stencil sheet, that i~, the side composed of the thin paper is exposed to electro-magnetic 20 radiation involving infrared rays to thereby effect perforation by fusion of said film in its area congruent with the image area of the original; subsequently, the original on the film-bonded surface of the stencil sheet is stripped away.
When printing paper is superposed on the perforated surface (i. e. film-bonded ~ide) of the thus obtained stencil and printing ink is applied by way of the side composed of the thin paper, the ink penetrates the thin paper, passes through the perforated area and comes to adhere onto said printing paper, thereby producing a mimeographic print carrying an image identical with the original.
As for the theory of the perforation taking place in the course of preparing said stencil sheet, the details thereof are yet to be clarified, 30 but it i8 presumably based on such mechanism as outlined in the following.
The radiation rich in infrared rays penetrates the thin paper, Bi ` -1-~.. ..
the layer of adhesi~e and the film layer in order, and, when it reaches the original, it is absorbed in the image area of the original, bringing about a sudden rise in temperature of said image area. Meanwhile, as to the non-image area of the original, the radiatiQn is scarcely absorbed therein, so that there is not much rise in temperature of said area. As a result, there is generated on the surface of the original a thermographic image showing light areas and shaded areas, that is, fluctuations in temperature quite identical with that of the image area of the original. This thermo-graphic image brings about a rise in temperature, and softening and simul-10 taneous heat shrinkage of the congruent area of a film neighboring or con-tacting therewith, until its central part is broken by fusion, whereby there i~ formed on the film a perforated image corresponding to the original ; image.
In the process of preparing the stencil described above, where tho amount of the radiation applied is appropriate, no noticeable trouble O
arioe~; but, generally speaking, inasmuch as the amount of the radiation i~ hard to control properly, it is apt to be applied excessively. As a result, .
thc fusion of the film in the course of preparing a stencil comes to be so exce~sive that the fuset film partially adheres onto the image area of the 20 original ant causes tamage to the image area of the original at the time of Jeparating the original from the stencil. The excessive radiation not only inflicts damage on the original but also causes the fused substance from the thus tamaget original to fill up the perforatet area of the stencil sheet, thereby obstructing the passage of copying ink at the time of mimeographic printing ant resulting in a remarkable tegeneration of the distinction of t'ne image on the print produced by means of a stencil obtained therefrom. This phenomenon of the film getting fuset is especially cons,>icuous in the case of an original image formet through offset printing ant the like. Ant, this is considered ascribable to the fact that the thermoplastic resin contained 30 in the offset E!rinting ink employed in forming the image tends to get fused due to the rise in temperature of the image area caused by said radiation and, when thus fused, it comes to adhere onto the film-bonded surface of the stencil ~heet.
104~424 SUMMARY OF THE INVENTION
The object of the present mvention is to provide a heat-sensitive stencil sheet absolutely free of the foregoing phenomenon of its film getting fused to cause adhesion.
The heat-sensitive stencil sheet according to the present invention comprises a porous thin paper having bonded thereon a heat-shrinkable thermo-plastic film consisting of any one of polypropylene, polyvinyl chloride, polyethylene, polystyrene, vinyl chloride-vinyl acetate copolymer, vinylidene chloride-vinyl chloride copolymer, etc. and further provided 10 with a thin layer consisting of a compound popular as the releasing agent formed onto the surface of said film. In other words, the stencil sheet according to the present invention employs a compound well known as a silicone resin for the purpose of rendering to the heat-sensitive stencil sheet releasable property or thermo-adhesion preventability and makes up for the shortcomings of conventional stencil sheets by virtue of a thin laycr formet onto the film-bonded surface of the stencil sheet and con-~i~ting ~ubstantially of said compound, ;; As a result of their extensive studies on how to provide a heat-:
en~itive stencil sheet with thermo-adhesion preventability necessary for prcparation of a stencil therefrom, the inventors of the present invention have come to the finding that any compound particularly effective in providing such property for said stencil sheet should be possessed of ~uch physical and chemical properties as set forth under 1)~6) in the following.
1) It scarcely absorbs the radiation in the range of 500----2, 000 m,~.
a) Field of the Invention The present invention relates to a stencil sheet which comprises a thin porous supporting sheet having bonded thereon a heat shrinkable synthetic resin film and is further provided with releasable property or heat-fusion preventability.
b) Description of the Prior Art A stencil for use in mimeographic printing can be readily prepared by employing a heat-sensitive stencil sheet comprising a porous 10 thin paper weighing about 8~V15 gm. per square meter, i. e. a porous supporting sheet consisting mainly of natural fiber obtained from mitsumata, paper mulberry, manila hemp, etc. or synthetic fiber cansisting of rayon, vinylon, tetron, acrylic fiber or the like and provided with a heat shrinkable thermoplastic film bonded thereon, such as, for instance, a film compris-~g vinylidene chloride-vinyl chloride copolymer. On this occasion, said ~tencil for use in mimeographic printing i9 obtained through the following processes: an original i9 brought into close contact with the film-bonded ~, ~urface of the foregoing stencil sheet; the back of the stencil sheet, that i~, the side composed of the thin paper is exposed to electro-magnetic 20 radiation involving infrared rays to thereby effect perforation by fusion of said film in its area congruent with the image area of the original; subsequently, the original on the film-bonded surface of the stencil sheet is stripped away.
When printing paper is superposed on the perforated surface (i. e. film-bonded ~ide) of the thus obtained stencil and printing ink is applied by way of the side composed of the thin paper, the ink penetrates the thin paper, passes through the perforated area and comes to adhere onto said printing paper, thereby producing a mimeographic print carrying an image identical with the original.
As for the theory of the perforation taking place in the course of preparing said stencil sheet, the details thereof are yet to be clarified, 30 but it i8 presumably based on such mechanism as outlined in the following.
The radiation rich in infrared rays penetrates the thin paper, Bi ` -1-~.. ..
the layer of adhesi~e and the film layer in order, and, when it reaches the original, it is absorbed in the image area of the original, bringing about a sudden rise in temperature of said image area. Meanwhile, as to the non-image area of the original, the radiatiQn is scarcely absorbed therein, so that there is not much rise in temperature of said area. As a result, there is generated on the surface of the original a thermographic image showing light areas and shaded areas, that is, fluctuations in temperature quite identical with that of the image area of the original. This thermo-graphic image brings about a rise in temperature, and softening and simul-10 taneous heat shrinkage of the congruent area of a film neighboring or con-tacting therewith, until its central part is broken by fusion, whereby there i~ formed on the film a perforated image corresponding to the original ; image.
In the process of preparing the stencil described above, where tho amount of the radiation applied is appropriate, no noticeable trouble O
arioe~; but, generally speaking, inasmuch as the amount of the radiation i~ hard to control properly, it is apt to be applied excessively. As a result, .
thc fusion of the film in the course of preparing a stencil comes to be so exce~sive that the fuset film partially adheres onto the image area of the 20 original ant causes tamage to the image area of the original at the time of Jeparating the original from the stencil. The excessive radiation not only inflicts damage on the original but also causes the fused substance from the thus tamaget original to fill up the perforatet area of the stencil sheet, thereby obstructing the passage of copying ink at the time of mimeographic printing ant resulting in a remarkable tegeneration of the distinction of t'ne image on the print produced by means of a stencil obtained therefrom. This phenomenon of the film getting fuset is especially cons,>icuous in the case of an original image formet through offset printing ant the like. Ant, this is considered ascribable to the fact that the thermoplastic resin contained 30 in the offset E!rinting ink employed in forming the image tends to get fused due to the rise in temperature of the image area caused by said radiation and, when thus fused, it comes to adhere onto the film-bonded surface of the stencil ~heet.
104~424 SUMMARY OF THE INVENTION
The object of the present mvention is to provide a heat-sensitive stencil sheet absolutely free of the foregoing phenomenon of its film getting fused to cause adhesion.
The heat-sensitive stencil sheet according to the present invention comprises a porous thin paper having bonded thereon a heat-shrinkable thermo-plastic film consisting of any one of polypropylene, polyvinyl chloride, polyethylene, polystyrene, vinyl chloride-vinyl acetate copolymer, vinylidene chloride-vinyl chloride copolymer, etc. and further provided 10 with a thin layer consisting of a compound popular as the releasing agent formed onto the surface of said film. In other words, the stencil sheet according to the present invention employs a compound well known as a silicone resin for the purpose of rendering to the heat-sensitive stencil sheet releasable property or thermo-adhesion preventability and makes up for the shortcomings of conventional stencil sheets by virtue of a thin laycr formet onto the film-bonded surface of the stencil sheet and con-~i~ting ~ubstantially of said compound, ;; As a result of their extensive studies on how to provide a heat-:
en~itive stencil sheet with thermo-adhesion preventability necessary for prcparation of a stencil therefrom, the inventors of the present invention have come to the finding that any compound particularly effective in providing such property for said stencil sheet should be possessed of ~uch physical and chemical properties as set forth under 1)~6) in the following.
1) It scarcely absorbs the radiation in the range of 500----2, 000 m,~.
2~ It is a pliable solid at room temperature.
3) It becomes softened or fused at a temperature of 60--~200C.
and the softening of fusion forms a sharp curve.
and the softening of fusion forms a sharp curve.
- 4) It has a low viscosity when fused.
5) Its fusion energy is little.
~ - 4 1~4~14Z4
~ - 4 1~4~14Z4
6) It has no harmful effect on the human body at a temperature ranging from room te~nperature to 200C.
And, the present invention is based on the knowledge they have obtained that, as the compounds h~ving said properties, the afore-mentioned silicone resins.
are available. Among the above itemized properties of these compounds or substances, the one under the item 3) is extremely important, that is, it is a 'must' that they be possessed of the property that they are fusible when subjected to radiation rich in infrared rays, namely at a temperature in the range of from 60 to 200 C. In other words, among those compounds known as silicone resins, 10 only such compounds as are fusible by heating at a temperature in the range of from 60C. to 200C. are applicable in the present invention. That is to say, the afore-mentioned thin layer formed onto the film-bonded surface of a stencil sheet should be possessed of such property.
The optimum silicone resin for use in the present inve~tion is a I x resin which has a siloxane bond expressed by the structural unit l -Si-O-l wherein any one o X and Y is hydrogen, an alkyl radical having 1 to 4 c on atoms, a phenyl radical or a hydroxyl radical, and at least one of the remaining bonds i9 combined with oxygen of another structural unit. That is, it has a structure such, for instance, as follows:
CH3 C1~3 f~3 1H3 : -O -Si-O -Si-O-Si-O- i-OH
CH3 ¦ CH3 CH3 ~ ~H3 - O - si - o - i - o - i - o - si - o -'CH3 1H3 1H ~H3 To give concrete examples of the silicone effective in preventing caid thermal adhesion, those substances popular as the silicic releasing agent or paper processing agent are all applicable in the present invention, ant they include, for instance, those manufactures of SHINETSU Chemical Ind. Co., Ltd. so~d under the trade names 'SHINETSU SILICONE RELEASING
AGENT-KS 707' (a varnish-type silicone releasing agent) and 'SH~ETSU
SILICONE; RELEASING AGENT KM 763' (an emulsion-type silicone releasi.lg J
A
1~)4~1424 agent), a manufacture of TORAY SILICONE; CO., LTD. sold under the trade name 'TORAY SILICONE SH 490' (an emulsion-type silicone releasing agent~, etc.
~s a typical silicone releasing agent, 'Union Carbide R-63 Silicone Resin' (the trade name of a manufacture of Union Carbide Corporation) can also be cited.
The thermo-a&esion preventing efficiency of a stencil sheet is influenced by the applied amount of the coating substance comprising silicone resin acting as above on the film-bonded surface of said stencil sheet, to wit, the more the amount applied, the more said efficiency is increased. However, in thecasewherethe applied amount is too much, there is a marked decrease in the distinction of the perforated image formed onto the processed stencil sheet.Such being the case, it is necessaryto seethat it be applied in an appropriate amount in order to attain a practically satisfactory efficiency for preventing the thermo-adhesion. Said appropriate amount t~ be applied depends on the kind~ of components of the coating substance and cannot be prescribed uniformly, but the suitable amount common to all coating substances is ~ the range of 0. 05~2. 0 gm. per square meter in terms of the weight upon perfect drying thereof, and preferably in the range of about 0.05--1.0 gm.
per ~quare meter.
Among those heat shrinkable films applicable in the present invention, a film comprising vinylidene chloride-vinyl chloride copolymer is , ~uitable, and especially the one mate up of (in terms of parts by weight) 80_95 (of vinylidene chloride): 20--5 (vinyl chloride) is suitable. Moreover, it i~ advisable to apply a film which has a thickness ranging from 5 to 10,~ anda heat shrinkage ranging from 2.6 to 15.0% in biaxial directions when ~ubjected to heating at 100C. for one minute. And, a film possesset of ~uch properties can be obtained by means of molding and stretching the afore-mentioned copolymer into the form of a film and subsequently subjecting it to heat treatment at 120C. for 3 to 30 seconds.
311~ Hereunder will be given the elucidation of the efficiency of the present invention in co:nparison with the conventional stencil sheet prepared by employing sodium stearate. 5 B' ~4~4Z4 The stencil sheet employing sodium stearate is inferior to the stencil sheet according to the present invention in the thermo-adhesion preventing efficiency because it fails to meet the above itemized requirements, and, in addition, is considerably inferior to the former in the distinction of the perforated area. This is indicated by the thermal movements of both agents.
That is, when their thermal properties are examined respectively by means of a differential scanning calorimeter, sodium stearate begins softening at about 50 C. and effects the maximum endothermic reaction at 150C., thus showing a very slow entothermic curve, and its energy of fusion being too large.
Besides, the minimum amount of coating of sodium stearate which is necessary to prevent thermo-adhesion is considerably greater than that of the release agent employed in the present invention. Further, from the viewpoint of property of matter, there is also a difference of property of matter based on the difference :
of the fundamental molecular structure between sodium stearate and silicones, and, particularly, the fact that the silicone is not miscible with organic compounds and has but a weak surface tension, in addition to the afore-mentioned 6 properties, constitute unique properties of matter which cannot be expected of conventional organic compounds such as sodium stearate.
Therefore, the minimum amount of coating to be effective in preventing ; ~0 . .
, ,B~
' ~ thermo-adhesion in the case of sodium stearate is considerably greater than that of the release agent required in the present invention. And, where a stencil prepared by employing the heat-sensitive stencil sheet according to the present invention is practically compared with its c counter-part prepared by employing the stencil sheet coated with sodium ~tearate, the former becomes perforated rapidly because of the required amount of said coated agent being small, while the latter becomes perforated slowly. Further, inasmuch as the afore-mentioned substances known as silicone releasing agents are possessed of excellent water-dispersibility, ~ 10 they are very convenient for preparing a stencil sheet: for instance, such ; a release agent in the form of an emulsion is usable as a highly concentrated aqueous dispersion, and, consequently, it can be coated at a higher speed, '~ br~ng~ng about the effect of enhancing the so-called working property.
Moreover, the fact that just a small amount of coating thereof sufices to obtain a satisfactory effect leads to a reduction in manufacturing cost.
In preparing a stencil sheet according to the present invention, it i~ desirable to follow the procedure whereby a film comprising, for instance I vinylidene chloride-vinyl chloride copolymer, is bonded onto the porous thin ; ~ paper and dried, ant thereafter the thermo-adhesion preventing agent is 20 applied; but it will also do to apply the thermo-adhesion preventing agent atthe time of forming the film or after forming the film and bond the thus treatedfilm onto the porous thin paper.
~PREFERRED EMBODIMENTS OF THE INVENTION
Example 1 A 7~ thick film comprising vinylidene chloride-vinyl chloride copolymer resin (component ratio 80:20) was subjected to heat treatment ' I at 100C. for 10 seconds. The thus treated film was bonded onto a 30,~
thick porous thin paper by means of vinyl acetate type adhesive ~a methanol solution) and dried, wherel>y a standard heat-sensitive stencil sheet was 30 pr epared.
i~ Subsequently, the film-bonded surface of said stencil sheet was coated with a 1. 0% n-hexane solution of 'SHINETSU SILICONE RELEASING
., ~ _7_ 1~404Z4 AGENT KS 707' as the thermo-adhesion preventing agent and dried at a temperature rangillg from 40 to 50C., whereby a thermo-adhesion preventive layer was formed thereon. The coated amount of said thermo-adhesion preventing agent in this case was about 0.05 gm. per square meter.
Example 2 The film-bonded surface of the standard heat-sensitive stencil sheet as prepared in Example 1 was coated with a 10% aqueous emulsion of ~SHINETSU SILICONE RELEASING AGENT KM763' as the thermo-adhesion ~, pre~renting agent and subjected to the same treatment subsequent thereto 10 as in the case of Example 1, whereby a thermo-adhesion preventive layer wa~l formed thereon. The coated amount of said thermo-adhesion prevent-ing agent in this case was about 0. 2 gm. per square meter.
Example 3 The film-bonded surface of the standard heat-sensitive stencil ~heet as prepared in Example l was coated with a 10% aqueous emulsion of 'TORAY SILICONE SH490' as the thermo-adhesion preventing agent and ~ubjected to the same treatment subsequent thereto as in the case of ! Example 1, whereby a thermo-adhesion preventive layer was formed thereon. The coated amount of said thermo-adhesion preventing agent in ; 20 this case was about 0.4 gm. per square meter.
Subsequently, for the purpose of comparing the efficiency of those 3 kinds of heat-sensitive stencil sheets prepared in Examples 1 and 2 and the present Example with that of a standard stencil sheet not provided with thermo-adhesion preventability, an original (namely, newspaper) each waC
made to closely contact with the thermo-adhesion preventive layer formed surface as for the stencil sheet under the present invcntion and the film-bonded surface as for the comparative standard stencil sheet, and the stencil sheets were then subjected to radiation rich in infrared rays applied from the side consisting of the thin paper, thereby effecting per-30 oration congruent with the original image, respectively. The resultant~tencil sheets for mimeographic printing were respectively separated from the original, and served for printing by a rotary mimeographic press.
The results were as follows.l~4~)424 In the case of the comparative standard stencil sheet, the areas of the original congruent with thick capital letters or solid printings having been fused to adhere onto the film-bonded surface, said areas of the original image were damaged at the time of separating ~he original sub-sequent to application of the radiation. And, when the thus obtained stencil was served for printing, those areas which had come to adhere by fusion hampered the passage of the copying ink, resulting in failure in forming a printet image which perfectly reproduces the original image, and 10 partially brought about blank spots in the printed image. Also in case of thin, small letters, there were observed slight adhesions by fusion and the edge areas of the image failed to form perfect lines, resulting in a lack of distinction or sharp definition of the printed image as well as inferior resolving power.
011 the other hand, in the case of the stencil 8heets prepared accordin~
to the present invention, the separation of the original therefrom subsequent to application of radiation rich in infrared rays was performed easily without encountering such troubles as in the former, and there was observed no thermal adhesion whatever onto the original or perforated area. And, 20 when the stencils were served for printing, they showed an extremely smooth flow of the copying ink, and, as a result, the stencils each could produce more than 2000 prints carrying an extremely distinct printed image nt faithfully reproducing the original image.
', ~ .
''~
~ .
B ~9-
And, the present invention is based on the knowledge they have obtained that, as the compounds h~ving said properties, the afore-mentioned silicone resins.
are available. Among the above itemized properties of these compounds or substances, the one under the item 3) is extremely important, that is, it is a 'must' that they be possessed of the property that they are fusible when subjected to radiation rich in infrared rays, namely at a temperature in the range of from 60 to 200 C. In other words, among those compounds known as silicone resins, 10 only such compounds as are fusible by heating at a temperature in the range of from 60C. to 200C. are applicable in the present invention. That is to say, the afore-mentioned thin layer formed onto the film-bonded surface of a stencil sheet should be possessed of such property.
The optimum silicone resin for use in the present inve~tion is a I x resin which has a siloxane bond expressed by the structural unit l -Si-O-l wherein any one o X and Y is hydrogen, an alkyl radical having 1 to 4 c on atoms, a phenyl radical or a hydroxyl radical, and at least one of the remaining bonds i9 combined with oxygen of another structural unit. That is, it has a structure such, for instance, as follows:
CH3 C1~3 f~3 1H3 : -O -Si-O -Si-O-Si-O- i-OH
CH3 ¦ CH3 CH3 ~ ~H3 - O - si - o - i - o - i - o - si - o -'CH3 1H3 1H ~H3 To give concrete examples of the silicone effective in preventing caid thermal adhesion, those substances popular as the silicic releasing agent or paper processing agent are all applicable in the present invention, ant they include, for instance, those manufactures of SHINETSU Chemical Ind. Co., Ltd. so~d under the trade names 'SHINETSU SILICONE RELEASING
AGENT-KS 707' (a varnish-type silicone releasing agent) and 'SH~ETSU
SILICONE; RELEASING AGENT KM 763' (an emulsion-type silicone releasi.lg J
A
1~)4~1424 agent), a manufacture of TORAY SILICONE; CO., LTD. sold under the trade name 'TORAY SILICONE SH 490' (an emulsion-type silicone releasing agent~, etc.
~s a typical silicone releasing agent, 'Union Carbide R-63 Silicone Resin' (the trade name of a manufacture of Union Carbide Corporation) can also be cited.
The thermo-a&esion preventing efficiency of a stencil sheet is influenced by the applied amount of the coating substance comprising silicone resin acting as above on the film-bonded surface of said stencil sheet, to wit, the more the amount applied, the more said efficiency is increased. However, in thecasewherethe applied amount is too much, there is a marked decrease in the distinction of the perforated image formed onto the processed stencil sheet.Such being the case, it is necessaryto seethat it be applied in an appropriate amount in order to attain a practically satisfactory efficiency for preventing the thermo-adhesion. Said appropriate amount t~ be applied depends on the kind~ of components of the coating substance and cannot be prescribed uniformly, but the suitable amount common to all coating substances is ~ the range of 0. 05~2. 0 gm. per square meter in terms of the weight upon perfect drying thereof, and preferably in the range of about 0.05--1.0 gm.
per ~quare meter.
Among those heat shrinkable films applicable in the present invention, a film comprising vinylidene chloride-vinyl chloride copolymer is , ~uitable, and especially the one mate up of (in terms of parts by weight) 80_95 (of vinylidene chloride): 20--5 (vinyl chloride) is suitable. Moreover, it i~ advisable to apply a film which has a thickness ranging from 5 to 10,~ anda heat shrinkage ranging from 2.6 to 15.0% in biaxial directions when ~ubjected to heating at 100C. for one minute. And, a film possesset of ~uch properties can be obtained by means of molding and stretching the afore-mentioned copolymer into the form of a film and subsequently subjecting it to heat treatment at 120C. for 3 to 30 seconds.
311~ Hereunder will be given the elucidation of the efficiency of the present invention in co:nparison with the conventional stencil sheet prepared by employing sodium stearate. 5 B' ~4~4Z4 The stencil sheet employing sodium stearate is inferior to the stencil sheet according to the present invention in the thermo-adhesion preventing efficiency because it fails to meet the above itemized requirements, and, in addition, is considerably inferior to the former in the distinction of the perforated area. This is indicated by the thermal movements of both agents.
That is, when their thermal properties are examined respectively by means of a differential scanning calorimeter, sodium stearate begins softening at about 50 C. and effects the maximum endothermic reaction at 150C., thus showing a very slow entothermic curve, and its energy of fusion being too large.
Besides, the minimum amount of coating of sodium stearate which is necessary to prevent thermo-adhesion is considerably greater than that of the release agent employed in the present invention. Further, from the viewpoint of property of matter, there is also a difference of property of matter based on the difference :
of the fundamental molecular structure between sodium stearate and silicones, and, particularly, the fact that the silicone is not miscible with organic compounds and has but a weak surface tension, in addition to the afore-mentioned 6 properties, constitute unique properties of matter which cannot be expected of conventional organic compounds such as sodium stearate.
Therefore, the minimum amount of coating to be effective in preventing ; ~0 . .
, ,B~
' ~ thermo-adhesion in the case of sodium stearate is considerably greater than that of the release agent required in the present invention. And, where a stencil prepared by employing the heat-sensitive stencil sheet according to the present invention is practically compared with its c counter-part prepared by employing the stencil sheet coated with sodium ~tearate, the former becomes perforated rapidly because of the required amount of said coated agent being small, while the latter becomes perforated slowly. Further, inasmuch as the afore-mentioned substances known as silicone releasing agents are possessed of excellent water-dispersibility, ~ 10 they are very convenient for preparing a stencil sheet: for instance, such ; a release agent in the form of an emulsion is usable as a highly concentrated aqueous dispersion, and, consequently, it can be coated at a higher speed, '~ br~ng~ng about the effect of enhancing the so-called working property.
Moreover, the fact that just a small amount of coating thereof sufices to obtain a satisfactory effect leads to a reduction in manufacturing cost.
In preparing a stencil sheet according to the present invention, it i~ desirable to follow the procedure whereby a film comprising, for instance I vinylidene chloride-vinyl chloride copolymer, is bonded onto the porous thin ; ~ paper and dried, ant thereafter the thermo-adhesion preventing agent is 20 applied; but it will also do to apply the thermo-adhesion preventing agent atthe time of forming the film or after forming the film and bond the thus treatedfilm onto the porous thin paper.
~PREFERRED EMBODIMENTS OF THE INVENTION
Example 1 A 7~ thick film comprising vinylidene chloride-vinyl chloride copolymer resin (component ratio 80:20) was subjected to heat treatment ' I at 100C. for 10 seconds. The thus treated film was bonded onto a 30,~
thick porous thin paper by means of vinyl acetate type adhesive ~a methanol solution) and dried, wherel>y a standard heat-sensitive stencil sheet was 30 pr epared.
i~ Subsequently, the film-bonded surface of said stencil sheet was coated with a 1. 0% n-hexane solution of 'SHINETSU SILICONE RELEASING
., ~ _7_ 1~404Z4 AGENT KS 707' as the thermo-adhesion preventing agent and dried at a temperature rangillg from 40 to 50C., whereby a thermo-adhesion preventive layer was formed thereon. The coated amount of said thermo-adhesion preventing agent in this case was about 0.05 gm. per square meter.
Example 2 The film-bonded surface of the standard heat-sensitive stencil sheet as prepared in Example 1 was coated with a 10% aqueous emulsion of ~SHINETSU SILICONE RELEASING AGENT KM763' as the thermo-adhesion ~, pre~renting agent and subjected to the same treatment subsequent thereto 10 as in the case of Example 1, whereby a thermo-adhesion preventive layer wa~l formed thereon. The coated amount of said thermo-adhesion prevent-ing agent in this case was about 0. 2 gm. per square meter.
Example 3 The film-bonded surface of the standard heat-sensitive stencil ~heet as prepared in Example l was coated with a 10% aqueous emulsion of 'TORAY SILICONE SH490' as the thermo-adhesion preventing agent and ~ubjected to the same treatment subsequent thereto as in the case of ! Example 1, whereby a thermo-adhesion preventive layer was formed thereon. The coated amount of said thermo-adhesion preventing agent in ; 20 this case was about 0.4 gm. per square meter.
Subsequently, for the purpose of comparing the efficiency of those 3 kinds of heat-sensitive stencil sheets prepared in Examples 1 and 2 and the present Example with that of a standard stencil sheet not provided with thermo-adhesion preventability, an original (namely, newspaper) each waC
made to closely contact with the thermo-adhesion preventive layer formed surface as for the stencil sheet under the present invcntion and the film-bonded surface as for the comparative standard stencil sheet, and the stencil sheets were then subjected to radiation rich in infrared rays applied from the side consisting of the thin paper, thereby effecting per-30 oration congruent with the original image, respectively. The resultant~tencil sheets for mimeographic printing were respectively separated from the original, and served for printing by a rotary mimeographic press.
The results were as follows.l~4~)424 In the case of the comparative standard stencil sheet, the areas of the original congruent with thick capital letters or solid printings having been fused to adhere onto the film-bonded surface, said areas of the original image were damaged at the time of separating ~he original sub-sequent to application of the radiation. And, when the thus obtained stencil was served for printing, those areas which had come to adhere by fusion hampered the passage of the copying ink, resulting in failure in forming a printet image which perfectly reproduces the original image, and 10 partially brought about blank spots in the printed image. Also in case of thin, small letters, there were observed slight adhesions by fusion and the edge areas of the image failed to form perfect lines, resulting in a lack of distinction or sharp definition of the printed image as well as inferior resolving power.
011 the other hand, in the case of the stencil 8heets prepared accordin~
to the present invention, the separation of the original therefrom subsequent to application of radiation rich in infrared rays was performed easily without encountering such troubles as in the former, and there was observed no thermal adhesion whatever onto the original or perforated area. And, 20 when the stencils were served for printing, they showed an extremely smooth flow of the copying ink, and, as a result, the stencils each could produce more than 2000 prints carrying an extremely distinct printed image nt faithfully reproducing the original image.
', ~ .
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Claims (6)
1. A heat-sensitive stencil sheet comprising a porous supporting sheet having bonded thereon a heat shrinkable thermoplastic film, the top surface of said film being coated with a thin layer containing release agents selected from the group consisting of silicone resin release agents having a siloxane bond expressed by the structural unit:
wherein any one of X ant Y is hydrogen, an alkyl radical having 1 to 4 carbon atoms, a phenyl radical or a hydroxyl radical, and at least one of the remaining bonds is combined with oxygen of another structural unit, the said release agents being flexible solids at room temperature, heat fusible at a temperature of from about 60°C. to 200°C. and substantially non-absorptive of radiation in the range of from 500 to 2000 millimicrons.
wherein any one of X ant Y is hydrogen, an alkyl radical having 1 to 4 carbon atoms, a phenyl radical or a hydroxyl radical, and at least one of the remaining bonds is combined with oxygen of another structural unit, the said release agents being flexible solids at room temperature, heat fusible at a temperature of from about 60°C. to 200°C. and substantially non-absorptive of radiation in the range of from 500 to 2000 millimicrons.
2. A heat-sensitive stencil sheet according to Claim l, wherein said thermoplastic film is a film consisting substantially of a polymer selected from the group consisting of polypropylene, polyvinyl-chloride, polyethylene, polystyrene, vinylchloride-vinylacetate copolymer and vinylidene chloride-vinylchloride copolymer.
3. A heat-sensitive stencil sheet according to Claim 2, wherein said film has a heat shrinkage at 100 C. for one minute in the range of from 2.6 to 15.0% in both biaxial directions.
4. A heat-sensitive stencil sheet according to Claim 1, wherein said thermoplastic film is a film consisting substantially of vinylidene chloride vinylchloride copolymer, and the copolymerization ratio of vinylidene chloride and vinyl chloride in said copolymer is in the range of from 30 to 95 parts by weight of the former per from 20 to 5 parts by weight of the latter.
5. A heat-sensitive stencil sheet according to Claim 1, wherein the thickness of said film is in the range of from 5 to 10µ and the weight per one square meter of said porous supporting sheet is in the range of from 8 to 15 grams.
6. A heat-sensitive stencil sheet according to Claim 1, wherein the amount of said releasing agent coated onto a surface of said film is in the range of from about 0.05 to 2.0g per one square meter of said film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA165,083A CA1040425A (en) | 1969-09-29 | 1973-03-02 | Heat-sensitive stencil sheet |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP44077994A JPS4830570B1 (en) | 1969-09-29 | 1969-09-29 | |
| JP7799369 | 1969-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1040424A true CA1040424A (en) | 1978-10-17 |
Family
ID=26419051
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA094,218A Expired CA1040424A (en) | 1969-09-29 | 1970-09-28 | Heat-sensitive stencil sheet |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1040424A (en) |
| DE (1) | DE2041730A1 (en) |
| DK (1) | DK129222B (en) |
| FR (1) | FR2062804A5 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3011958B2 (en) * | 1990-03-14 | 2000-02-21 | 株式会社興人 | Heat-sensitive stencil paper |
-
1970
- 1970-08-22 DE DE19702041730 patent/DE2041730A1/en active Pending
- 1970-09-14 DK DK472870A patent/DK129222B/en unknown
- 1970-09-28 CA CA094,218A patent/CA1040424A/en not_active Expired
- 1970-09-29 FR FR7035248A patent/FR2062804A5/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DK129222C (en) | 1975-02-03 |
| DE2041730A1 (en) | 1971-05-06 |
| DK129222B (en) | 1974-09-16 |
| FR2062804A5 (en) | 1971-06-25 |
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