DE2041730A1 - Heat-sensitive stencil sheet - Google Patents

Description

Kabushiki Kaisha Ricoh 2 for Aug 1970

Tokyo, Japan

Heat-sensitive stencil sheet

The invention relates to a heat-sensitive stencil sheet and deals with its layer structure

It is well known that a transfer stencil can be easily used with the help of this of a heat-sensitive stencil sheet that in turn from a porous thin paper of about 8 to 15 g / weight made from Mltsumata, mulberry, Manila hemp or the like - Natural fiber or rayon, vinylon, tetron, acrylic or like - synthetic fiber on which a heat shrinkable thermoplastic film made of e.g. vinylidene chloride-vinyl chloride copolymer stuck on 1st. Such a stencil sheet is covered on the film side with the one to be reproduced in a close-fitting manner Original and then exposes it from the opposite side with electromagnetic, infrared radiation, whereby the film layer is melted and perforated in the places corresponding to the original image areas, and finally pulls the original from the film side. With the template obtained in this way one then produces transfers in such a way that printing paper is placed on their film side and on their paper side Applying printing ink that penetrates the thin paper, penetrates into the perforated film areas up to the printing paper and creates a true-to-original imprint on it.

How the process of film perforation in stencil production plays in detail is not yet fully clarified. But the following is likely to happen

, 09819/1697

The infrared-rich radiation successively penetrates the carrier paper, the adhesive intermediate layer and the film itself up to the original, where they are hardly in the non-image areas, but strong in the image-bearing areas is absorbed and consequently only the latter very quickly highly heated. A thermographic image is thus created on the surface of the original, which is differentiated in terms of temperature largely corresponds to the light and dark areas of the original, is transferred to the film layer »it accordingly heats up differently, only softens in the hottest areas and heats up until the Break open central parts of the melted areas. This ultimately creates a perforation image that corresponds to the original image in the film layer »

If the correct amount of radiation is used in such a stencil production process, there will be no noticeable interference · However, since, generally speaking, the amount of radiation can only be adjusted correctly with difficulty, excessive irradiation can result, which melts the film too much »Er then sticks to the original and causes damage when it is detached. In addition, the "dissolved original particles" also fill the perforated area of the stencil sheet. During the subsequent transfer printing process, however, this means that the printing ink cannot pass through these areas and the image sharpness of the prints made with such a stencil noticeably suffers. This process of sticking the film occurs in particular with originals obtained by offset printing and the like, because the heat energy radiated in during the production of the stencil also melts the original image areas due to the thermoplastic resin contained in the offset printing ink and allows the melted mass to adhere to the film.

The invention now aims to provide a thermosensitive Stencil sheet, in which the aforementioned problem of sticking the filin to the original has been completely eliminated.

The invention accordingly basically consists of a heat-sensitive Stencil sheet made from a thin, porous carrier paper together with glued-on, heat-shrinking, thermoplastic Film made of polypropylene, polyvinyl chloride, polyethylene, polystyrene, vinyl chloride-vinyl acetate copolymer, vinylidene chloride-vinyl chloride copolymer or the like, the characteristic feature of which is that it has a thin film side Layer of a release agent on the one hand and a surface-active substance of the known type on the other hand is covered. Different Expressed, the stencil sheet according to the invention has a compound known as a silicone resin and a compound known as an anionic surfactant to to give it detachability and to take away heat adhesiveness and thus the aforementioned imperfections of the usual Turn off stencil sheets.

In the extensive attempts to suppress heat sticking The following target properties resulted for such remedial substances:

1) they must hardly absorb radiation in the wavelength range from about 500 to about 2000 iiyu;

2) they must be a pliable substance at room temperature;

3) they must soften or between about 60 ° and about 200 ⁰ G with hot melt curve;

4) they must be of low viscosity when molten;

5) they must have low melting energy;

6) they must be harmless to the human body between room temperature and 200 ° G.

- 4 100018/1667

The invention is now based on the experimental experience that the aforementioned silicone resin and the anionic surface-active substance are suitable as compounds with these properties. Of the above-mentioned properties is that in accordance with point j5) of utmost importance that both types of connections must necessarily under the action of infrared radiation between about 60 ° and about 200 ⁰ C to melt, and only these representatives of them, upon heating to 60 ° to about 200 ^° C. melt are suitable for carrying out the invention, and the stencil sheet cover layer according to the invention must also have this property.

Of the anionic surfactants, the most suitable sulfonate and sulfate type compounds are as follows general formulas a) or b), namely

a) R ₁ SO ₃ M

in the R- one

Alkyl radical with 10 to 30 carbon atoms or Alkenyl radical with 10 to JO carbon atoms or phenyl radical of the formula

R ¹

with R 'equal to one

Alkyl radical with 8 to 25 carbon atoms or Alkenyl radical with 8 to 25 carbon atoms

or
Acylamino radical of the formula

R ",
R " ¹
with R _TT equal to one

1Ö9819 / 1697

Alkyl radical with 8 to 25 carbon atoms or alkenyl radical with 8 to 25 carbon atoms

with R "equals one

Hydrogen atom or alkyl radical with 1 to 6 carbon atoms and

with R ¹ "equal to one

Alkylene radical with 1 to 10 carbon atoms

and

M denotes a potassium, sodium or ammonium radical

or

b) R _TTT OSO, M ^f

Hi ρ

in the R _TTT one

Alkyl radical with 10 to 30 carbon atoms or Alkenyl radical with 10 to 30 carbon atoms or acylamino radical of the formula

^Rt in

> NC0R ' _TT

pit S II

^R III

where R ¹ J ₁₁ is an alkyl radical having 8 to 25 carbon atoms or an alkenyl radical having 8 to 25 carbon atoms and

with R ¹¹ TTT equal to one

Hydrogen atom or alkyl radical with 1 to 8 carbon atoms and

with R'tt equal to one

Alkenyl radical with 1 to 10 carbon atoms

and M ^{1 is} a potassium, sodium or ammonium residue

mean.

-

109019/1667

In the invention, at least one of these two formulas a) - or formula b) compounds, i.e. these sulfonates or sulfates, as agents preventing heat adhesion or separating agents used.

Suitable formula a) compounds include, for example

Sodium Dodecanesulfonate C ^ ₂ H ₂₁ - · S 0, Na

Sodium 4-dodecyl benzenesulfonate

Sodium triacontanesulfonate

Sodium 6-dodeeene sulfonate C ₁₂ H ₂₅ * SO ₅ Na Sodium 15-triacontene sulfonate C ^ ₀ Hp sodium 4-pentacosyl benzenesulfonate C

2- (N-methyl-oleyolamino) ethane sodium sulfonate

CON 'C ₂ H ^. SO ₅ Na CH ₅

10- (N-hexyl-oleyolamino) decane sodium sulfonate

- CMI- C ₁₀ H ₂₀ - SO ₃ Na

° 6 ^H 1?

2- (N-methyl-s tearoylamino) ethane sodium sulfonate

CON -CgH ^ · SO ₅ Na

- γ 10 9813/169?

2OA1730

10- (N-Hexyl-stearoylamino) deean sodium sulfonate

G ₁₇ H ₃₅ . CON -C ₁₀ H ₂₀ - SO ₅ Na

^C 6 ^H 1? and the like corresponding compounds.

Za, on the other hand, include suitable formula b) compounds, for example

Sodium Dodecyl Sulphate ^ 1 ^ 25 * Nafcrium Triacontyl Sulphate Sodium 6-dodecenyl Sulphate

Sodium 15-triacontenyl sulfate ^C 30 ^H 59

2- (N-methyl-oleyolaraino) ethyl sodium sulfate

CON -C ₂ H ₄ · OSO ₅ Na

1O- (N-Hexy1-oleyolamino) decy1-sodium sulfate

C ₁₇ H ₅₃ - COH. C ₁₀ H ₂₀ - OSO ₃ Na

^{Compounds corresponding to C} 6 ^H 13 and the like.

Instead of the above-mentioned sodium compounds, of course also the corresponding potassium or ammonium compounds be used for carrying out the invention.

1 OdÖ19 / 16Ö7

These aforementioned anionic surface-active substances not only have the six properties listed above, but are also advantageous in that they have high water solubility and are suitable for use in manufacturing Stencil production have the necessary value for money.

Suitable silicone resins include those resins in which there is a siloxane bond of the structural unit

-Si-O-

is contained in the X and Y each a hydrogen atom, one Mean alkyl radical with 1 to 4 carbon atoms, a phenyl radical or a hydroxyl radical and at least one of the remaining bonds with the oxygen atom of another structural unit · So these resins have, for example, the structure

- 0- Si
t 0 0 CH,
ι ?
-Si -
1 0 - CH ₃
Si -0 -Sl -
1 OH CH ₃ ? CH ₅ 0
I. - 0 - Si -
t -Si-
t 0 - Si - 0
t -Si-
t 0 CH, OH ₃ OH ptl
WH,

To reduce the thermal adhesion according to the invention, for example, those substances are suitable which are known as silicon-containing release agents or paper finishing agents, and among them, for example, the lacquer-like silicone release agent, as it is available from Shinetsu Ind. Co. under the protected trade name "SHINETSU SILICON RELEASING AGENT-KS7O7" , and the silicone emulsion release agent available from Toray Silicon Co. Ltd. is supplied under the protected trade name ¹¹ TORAY SILICON SH 490 ".

Of the commercially available anionic surface-active substances based on sodium dodecyl benzenesulfonate are as most common the "NEOPELEX ®-6" product from Kao Atlas Co. Ltd., Japan, the "NACCONOL ^ NR" product of National Aniline & Chem. Co., V.St.Am., the "IQEPEL ^ NA" product of IG Farben Industrie and the like called.

The "Union Carbide ^ R-6j3 Silicone Res in" product from Union Carbide Corporation may also be mentioned as a typical silicone release agent.

In and of itself is the thermal adhesion of a stencil sheet the lower, the more silicone resin or surfactant-containing substances Coating substance applied to its film side will. Too much of it, however, leads to a noticeable decrease in the sharpness of the perforation image created on it later, and therefore one must pay attention to the correct application amount, a practically sufficient reduction in thermal adhesion to achieve. The correct amount depends on the type of top layer components and therefore cannot generally applicable. For all coating substances, however, the suitable amount is between about 0.05 and

about 2.0 g / m 2 and the preferred amount between about 0.05 and about 1.0 g / m 2, each based on completely dried substance.

- 10 -

10ÖÖ19 / 16Ö7

A suitable heat-shrinkable film for carrying out the invention is one made from vinylidene chloride-vinyl chloride copolymer, in particular in the range between about 80:20 and about 95-5 percent by weight. One places such a film in a thickness of about 5 to 10 / U, and adds a heat shrinkage of 2.6 to 15.0% in biaxial direction for 1 minute-ending heating to 100 ⁰ C. It provides him for example by Strangverpressung and Heckung the above-mentioned copolymer to the film and subsequent, j} to 30 seconds long heat treatment at 120 ⁰ C forth.

The performance of the stencil sheet composed according to the invention is explained below in comparison with the conventional stencil sheet, in the production of which sodium stearate is used for the same purpose instead of the inventive, anionic surface-active substance. The latter is inferior with regard to the suppression of thermal adhesion because it does not meet the six requirements listed above, and on top of that it also provides less sharp perforation images. This inferiority is due to the different thermal movements of the two substances. Namely, when examined their thermal properties by differential scanning calorimeter, then begins Natrlumstearat at about 50 ⁰ C to soften and causes the maximum endothermic reaction at 150 ^o C, thus showing a very flat endothermic curve, whereas the present invention, the heat adhesion-suppressing agent, eg sodium dodecyl benzenesulfonate, has a very sharp endothermic curve ^{at about 120 ° C.} From these observations it can be concluded that the inability of sodium stearate to suppress heat adhesion is due to the flat melting curve and the excessive melting energy. In addition, the minimum amount required to achieve the suppression effect is significantly greater in the case of sodium stearate than in the case of the substances used according to the invention. This difference in quantity

- 11 -

1ÖÖ819 / 16Ö7

is also noticeable in practice by the fact that a sodium stearate-coated stencil sheet because of the required large amount of sodium stearate much slower than the one according to the invention, which carries only a little covering layer substance Stencil sheet is perforated. Since, in addition, according to the invention As already mentioned, the release agents used have a high water solubility which is far higher than that of sodium stearate have, they can be prepared as a highly concentrated solution and correspondingly faster if the same equipment is used can be applied, thus improving machine performance. Another cost saving results from that you can use water as a solvent and not, as before, need an organic liquid.

From the point of view of the material properties, it also results from the diverse molecular structure on the one hand from sodium stearate and on the other hand from silicone resin a difference in that the latter - apart from the Six critical properties mentioned above - is not miscible with organic compounds and only low Has surface tension. All these properties cannot be found in common organic compounds Expect sodium stearate. Because of these superior properties, these are also known as silicone release agents Substances with the aforementioned advantages are based on the fact that they are effective even in small amounts, i.e. cheap to use and allow quick perforation. They also have high water dispersibility and can therefore be used as highly concentrated emulsion can be applied with high machine performance.

During the production of the stencil sheet according to the invention it is advisable to proceed in such a way that the porous, thin backing paper first a film made of e.g. vinylidene chloride-vinyl chloride copolymer sticks and dries up and

- 12 -

100619/1 ^ 97

then the heat adhesion suppressing layer is applied. Instead, this separating layer can also be used with the film during or after its shaping and before it Unite glue on the backing paper.

The invention is explained in more detail below with reference to a few preferred exemplary embodiments, without being restricted to them to be.

example 1

A 7 ax thick film of So ^ O-vinylidene chloride-vinyl chloride copolymer was first heated to 100 ° C for 10 seconds and then glued to porous thin paper (from JCyU thickness) with the help of a vinyl acetate adhesive (in methanolic solution) and dried ,

Then was thus prepared, standard according, stencil sheet wärmeempfindliehe film side with a 1 #igen solution (in hexane) of the previously mentioned Handeisproduktes "SHINETSU SILICONE RELEASING AGENT KS 707" is applied as the heat adhesion-suppressing agent, and at about 4o ° to 50 ⁰ C to a 0.05 g / m 2 separating layer according to the invention dried on.

Example 2

Example 1 was repeated with the modification that a 10 # aqueous emulsion of the commercial product "SHINETSU SILICON RELEASING AGENT KM 763 "and applied at a rate of about 2.0 g / m heavy, inventive separating layer was dried.

101819/1611

Example 3

Example 1 was repeated with the modification that a 10 # aqueous emulsion of the commercial product "TCHAY SILICON SH 490" mentioned earlier was applied and dried to give a separating layer ^{according to the invention weighing about 0.4 g / m 2.}

In order to make a comparison between those described in Examples 1 to 3, stencil sheets according to the invention and a conventional stencil paper without preventing thermal adhesion To obtain a separating layer, all comparative samples on the separating layer or free film layer side were each with an original (in the form of newspaper) closely covered and then exposed from the paper side with infrared-rich radiation, whereby their film layer was perforated congruently with the original. The transfer stencils obtained in this way were replaced by the original, inserted into a rotary printer and used for transfer printing. This resulted in the following:

In the comparison standard stencil sheet, the original stuck to the film-bearing surface at the location of the bold capital letters or closed image areas and was damaged at these points when later detached from the stencil sheet. During the subsequent original printing process, the ink penetration was prevented at these glued areas, so that the print was not true to the original and was also spotty. But even with the fine lower case letters there was a slight melting j and the image edges were not line-sharp, so that all in all the print lacked image sharpness and resolution.

Qanz On the contrary, it was found in the case of the The original can easily be removed from the stencil sheets after exposure and without any sticking to the perforated areas.

-U-

1U9819 / 1697

^ XT " ^m

peel off len. During the Umdruokvorgang itself a exceptionally good ink penetration, and all three More than 2000 stencils were able to deliver exceptionally sharp and faithful prints.

Example 4

Example 1 was repeated with the modification that a 15% aqueous sodium dodecyl sulfate solution was applied to the film surface in the form of the commercial product of Wako Pure Chemicals Co., Ltd. Japan applied with the help of a 500 mm water column dynamic pressure working air knife spread out and at 4o ° bis 50 C to a 0.3 g / m heavy separating layer with a die Heat-sticking agent has been dried up.

Example 5

Example 4 was repeated with the minor modifications that a 10 # solution of sodium dodecyl sulfate was applied and dried to form a separating layer weighing only about 1.0 g / m 2 became.

Example 6

Example 4 was repeated with the modification that a 8 #lge aqueous solution of the ammonium salt of the lauryl alcohol sulfuric acid ester in the form of the commercial product "EMAL A" from Kao Atlas Co., Ltd. applied and at a 0.2 g / m heavy separating layer was dried up.

Example 7

Example 4 was repeated with the modification that a 5 % Ige aqueous solution of Oleoylaininoäthan-natriunisulfonat

- 15 -

10 3 819/1697

- 15 -

^ "" C ₁₇ H ,, 'CON (CH,) "CpH ^« SO, Na_7 in the form of the commercial product "DIAPONT ^ paste" from Nippon Oils and Fats Co., Ltd. on

wear and dried to form a separating layer weighing 0.4 g / m 2 became.

Example 8

Example 4 was repeated with the modification that the 10 # aqueous sodium dodecyl sulfate solution had the equivalent Amount of a 10 # aqueous dodecylbenzenesulfonate solution added and this mixture applied and to an approx 0.5 g / m 2 heavy separating layer was dried.

The five stencil sheets according to the invention according to Examples 4 to 8 were then made in the manner described in Example J. with a normal stencil paper without preventing thermal adhesion Separating layer compared and showed in terms of original removability and quality of the transfer prints made with them have the same superiority as in the comparison test according to Example j3.

- 16 -

109819/1697

Claims (8)

Claims Wärmeempfindliohes stencil sheet of a porous, thin backing paper, together with glued heat-shrinkable, thermoplastic film, characterized in that on the film side with a thin layer of one hand, a release agent in the form of a heat-fusible between 60 ° and 200 ⁰ C silicone resin and on the other hand a likewise between 60 ° and 200 ⁰ C heat-fusible, anionic surfactant is covered. 2. stencil sheet according to claim 1, characterized in that the anionic surface-active contained in the cover layer Substance of at least one compound in the form of a sulfonate compound of the general formula a) in the R ₁ one Alkyl radical with 10 to 30 carbon atoms or Alkenyl radical with 10 to 30 carbon atoms or Phenyl radical of the formula R ¹ - with R ¹ equal to one Alkyl radical with 8 to 25 carbon atoms or alkenyl radical with 8 to 25 carbon atoms or acylamino radical of the formula - 17 - 109819/1697 204173Ö H | with R ₁₁ equal to one Alkyl radical with 8 to 25 carbon atoms or alkenyl radical with 8 to 25 carbon atoms with R "equals one Hydrogen atom or Alkyl radical with 1 to 6 carbon atoms and with R " ¹ equal to one Alkylene radical with 1 to 10 carbon atoms and M denotes a potassium, sodium or ammonium radical or a sulfate compound of the general formula b) in the Rjtj one Alkyl radical with 10 to JO carbon atoms or Alkenyl radical with 10 to JO carbon atoms or acylamino radical of the formula III with R'txt equal to one / NCOR ¹ pH - IB - 10 ^ 819/189? - Io - Alkyl radical with 8 to 25 carbon atoms or Alkenyl radical with 8 to 25 carbon atoms and ^{with R} "iii equal to one Hydrogen atom or Alkyl radical with 1 to 8 carbon atoms and with R ¹ TT equal to one Alkenyl radical with 1 to 10 carbon atoms and M * a potassium, sodium or ammonium residue mean exists. 3. stencil sheet according to claim 1 or 2, characterized in that « that a main component of the silicone resin contained in the top layer consists of a polysiloxane with the Structural unit X
t -Si-O-i in which X and Y are each a hydrogen atom, an alkyl radical with 1 to 4 carbon atoms, a phenyl radical or a hydroxyl radical, consists. 4 »stencil sheet according to one of the preceding claims, characterized in that the thermoplastic film consists mainly of a polymer in the form of polypropylene, polyvinyl chloride, ■ polyethylene, polystyrene» vinyl chloride-vinyl acetate copolymer or vinylidene chloride-vinyl chloride copolymer. - 19 - 1098 IS / 1697 5. Stencil sheet according to one of the preceding claims, characterized in that the thermoplastic film has a heat shrinkage of 2.6 to 15.0 % in both biaxial directions when ^{heated to 100 ° C. for 1 minute} 6. stencil sheet according to any one of the preceding claims, characterized in that the thermoplastic film from a copolymer of vinylidene chloride and vinyl chloride in a weight mixing ratio between 80: 20 and 95 to 5 exists. 7. Stencil sheet according to one of the preceding claims, characterized in that the thermoplastic film is 5 to 10 / U thick and the carrier paper weight is ^{8 to 15 g / m 2.} 8. stencil sheet according to one of the preceding claims, characterized in that the applied to the film side Amount of release agent 0.05 to 2.0 g / m film area amounts to. 109819/1697