DE1258427B - Thermal copying process - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

B 41m

German class: 15 k-7/05

Number: 1258 427

File number: C 33185 VI b / 15 k

Filing date: June 19, 1964

Open date: January 11, 1968

The invention relates to improvements in the thermographic method of labeling more flexibly Copy sheets and stencil sheets as well as the new transfer sheets used for this purpose.

With the known thermographic transfer methods for labeling copy sheets, Planographic printing forms and hectographic transfer originals directly absorbing infrared radiation Original image locations are the original image locations with a transfer sheet and a copy sheet ίο or a stencil sheet, and infrared radiation is directed onto the original image areas, which is absorbed by these image areas when they are heated. The image areas conduct a heat pattern onto the transfer sheet, which results in a softening of the coating composition of the transfer sheet which then adheres to the image areas on the copy sheet or the stencil sheets. After separating the The copy sheet or the template sheet and the transfer sheet carry the copy sheet or the template sheet visible corresponding to the image areas of the original sheet, if necessary for the generation of further ones Image areas suitable for copies.

Since the transfer sheet must be substantially free from infrared radiation absorbing materials, as and since the transmission mass located on it may only be so easily connected to the carrier that if they are almost completely detached from it during the thermographic process, they have become thin Plastic films as extremely suitable supports for transfer sheets to be used in thermography proven.

Although such transfer sheets with carrier films provide excellent transfers, arose due to the tendency of the plastic film to pucker and close in the heated areas shrink, new problems. The lack of the transfer sheet, copy or stencil sheets Adhering flatly and continuously to the heated areas has the creation of blotchy copies or of copies with blank lines or with continuous serpentine lines.

It is therefore an object of the invention to provide transfer sheets with carrier films for use in thermography, which do not pucker or shrink at the heated image areas and therefore enable the heat transfer of copied image areas that are sharp and uniform without free spaces or interruptions.

An advantage of the invention is that the new transfer sheets with carrier films and the units containing these transfer sheets are thermal copying processes

Applicant:

Columbia Ribbon and

Carbon Manufacturing Co., Inc.,

Glen Cove, Long Island, N.Y. (V. St. A.)

Representative:

Dipl.-Ing. E. Prince, Dr. G. Hauser

and Dipl.-Ing. G. Leiser, patent attorneys,

8000 Munich-Pasing, Ernsbergerstr. 19th

Named as inventor:

Douglas Alexander Newman,

Glen Cove, Long Island, N.Y. (V. St. A.)

Claimed priority:

V. St. v. America July 29, 1963 (298 402)

are easier to handle and treat than the previously known transfer sheets with carrier films.

The following description explains the invention in more detail.

It has now been found that the tendency of the carrier film of transfer sheets to adjust to the to pucker and shrink heated image areas, can be almost completely overcome can that you either before or after application of the transfer layer with a plastic film Coating with an antistatic agent that does not absorb appreciable amounts of infrared radiation Contains substances. The reason why or how such treatment this problem of the Preventing shrinkage or curling of the film at the heated areas is not known, as the The presence of static charge on the film itself has the advantage that the film adheres firmly to the copy sheets or stencil sheets in contact with it sticks. One possible explanation might be be that the strong attraction between the statically charged film and the copy sheet or the Die arches cause air inclusions and that this air forms tiny pockets that make up one hundred percent Contact between the transfer sheet

709 718/368

3 4

and the copy sheet or the stencil sheet. The coating solution is applied to the

prevent. ■ pulled side of the film wound, and the excess

The choice of the carrier for the invention is removed with a squeegee. The fleeting one Transfer sheets of each film used is solvent then first with an air non-solvent especially important, apart from the fact that the 5 blower removed, practically the entire Lö-FiIm Cores are allowed to absorb infrared radiation and thus evaporate the solvent. The coated film runs thin must be that he heats generated in it - then over a hot roller, on which the rest pattern does not scatter. Preferably, the film has one of the solvent driven off and the solid maxima Thickness of about 76.9 μ and a minimum of the composition melted together of about 7.7μ. Suitable films are for example io zen; the temperature of the hot roller is like this wise those made of polyethylene terephthalate polyester, sized so that the coating residue melts and Polyethylene, polypropylene, chlorinated rubber, poly to a coherent, but very thin, tetrafluoroethylene, polyvinyl chloride, cellulose acetate hard film bonds. and the like - · ■ - .._...... Although solid glycols with lower molecular

The antistatic treatment is preferably 15 weight, e.g. B. 900, are somewhat hygroscopic and would derive in the application of the antistatic agent and therefore any static electrical charge that a binder-containing coating might accumulate using a coating, are such agents of a solvent. The coating is relatively soft before coatings and melt preferably applied in such amounts that at fairly low temperatures. Therefore, a thin, 20-weight antistatic film is not suitable as coatings which form from about 0.0036 to about 0.036 g / m ² ; However, depending on the type of door that may have to withstand changes in thermographic processes, temperature changes are possible, especially if there are beam-specific components of the coating. treatment devices, such as. B. a thermal fax machine,

The following examples illustrate suitable anti- can be used. On the other hand, fixed GIy-

static coating solutions: 25 koles with a molecular weight in the range of

4,000 to 20,000 higher melting films with a

Example 1 Minimum melting temperature of about 49 ° C in the case

_. ,., from Carbowachs 400 and higher in the case of Carbowachs

17 * ", ·· ♦!., ·, 1, ™ ,,, ^{weight parts} 6000 and 20 000.

Solid ^ polyethylene glycol, molecular According to the invention it is necessary that the anti-

weight 6000 - »Carbowachs« .... 2.0 _static ^ _{at deQ bd dem Λβπη08ΠφΗ} _

Stearamidopropyldimethyl ^ -hydroxy- ■ - _Shem procedures used in this ·

Ethyl ammonium nitrate (temperatures not encountered on drying equipment

τ? WA ^- ^ r * ei λ ΟΊΥ ··· .. ···· 'melts. Such melting does one

Festetofe-Na-Sid *. of the sulfonic acid. Heat transfer from the coating to the

dioctylbernstemsaureesters - Aero- ³⁵ ^^ ^ f ^ bow or on the strap

Tir ^S ° c . ···········. · ■■ "· '..:; / 7 ·'""'or the rollers or the glass frame of the

Anhydrous, denatured ethyl alcohol _{device if the contact is made with it}

^boi _9b £ _ is coming.

100, Q. 40 According to the preferred embodiment of the

. . the antistatic coating melts itself

B e 1 s ρ 1 e 1 2 _the original image areas that generate heat.

Parts by weight of speaking places do not and do not go over; one

Solid polyethylene glycol, molecular composition of this type is illustrated in Example 3.

weight 20,000 - »Carbowachs« .. 2.0 45 Although the generated degree of heat is in these places

Stearamidopropyldimethyl-zS-hydroxyls can only be determined poorly, but over-

ethylammonium nitrate (on dry trains with a melting temperature of 93 ° C and

basis) - »Catanac SN« 1.0 higher have the required thermal stability in order to

Solids-NA salt of sulfonic acid- a melt and a transition in the heated dioctylsuccinic acid ester - To withstand aerodynamic areas of the image, should OT 0.1 Suitable heat-resistant, antistatic over water 5.0 draws are those based on film-forming binders, anhydrous, denatured ethyl agents with a melting temperature of around 121 ° C

alcohol 91.9 and above. Typical film-forming agents to be used

55 substances are ethyl cellulose, methyl cellulose, ethyl hydroxyethyl cellulose, Polyvinyl chloride and poly

Example 3 vinyl acetate and copolymers of the same, poly

. ., vinylbutyral, vinyldene chloride polymers and

_x . _{,, 1t} , uewicmsteiie -mischpolymerisate, polystyrene, Polyäthylenu. like

Ethyl cellulose 10.0 _6o although the antistatic coating in the

Stearamidopropyldimethyl- ^ hydroxy- _{erMtzteQ Büdstellen generated} temperatures before-

Ethylammonium nitrate (does not melt when dry, but is included in the invention

π ^b f _t ^ls ) "Τ / ^ ^{a anac} , ^{SN <<} " ■ · ■ ■ ·:. ···· ⁷ ' ⁶ also the use of coatings in these

^F ^ toff £ Na salt of the sulphonic _{acid- siteQ meltable} | _{nd however} § _{ei the at that}

dioctylbernstemsaureesters - Aero- _6g thermographic _C hen process occurring temperature

,, ^s ° yz, V ₁ "'''''οί,' ί doors do not melt. Such coatings can open

Metnyiatnynceton, ül, ö based on _the higher melting Carbowaxes or

100.0 on other hard waxes, e.g. B. carnauba wax or

Mixed breeds of wax with natural or synthetic resins. Such coatings are allowed at temperatures Do not melt below about 49 ° C and preferably melt at temperatures below about 66 ° C not yet.

It has been found that by adding antistatic substances immune to infrared radiation, e.g. stearamidopropyldimethyl-ß-hydroxyethylammonium nitrate, the hard carbowax coatings and the coatings based on film-forming binders can easily be made conductive for static charges without the coating noticeably softening, so that a non-greasy, dry feeling film is obtained. Though Catanac proves to be has proven to be an excellent antistatic agent, other common antistatic agents can also be used, z. B. succinic acid nitrile, magnesium nitrate and other similar ionic substances are used, provided that they are transparent to infrared radiation and do not absorb it to any appreciable extent.

The antistatic coating can be applied either before or after the transfer coating is applied on one or both sides of the carrier film. Preferably, however the antistatic coating is applied first, causing re-heating of the transfer coating is avoided during the drying of the antistatic coating. The anti-static coating will preferably applied to only one side of the carrier film, and the heat transferable layer is then applied to the other side of the carrier. If necessary, the transferable, image-generating Layer can also be incorporated into the antistatic compound.

The above examples illustrate the invention without, however, restricting it. Instead of Antistatic agents mentioned in the examples and the wax and resin binders can also be other commonly used, the main condition being that they do not contain appreciable amounts of infrared radiation absorb and that they at the temperatures generated in the thermographic process, d. H. Form non-melting, antistatic films at temperatures below about 49 ° C.

The heat transferable coatings on the transfer sheets of the present invention can be the conventional ones known for this purpose; however, they must melt below the melting temperature of the antistatic coating used and above the operating temperatures that occur. That is, both the antistatic coating and the imaging coating must melt above about 49 ° C; however, the antistatic coating must have at least a slightly higher melting temperature than the imaging coating. If the transfer layer is used to write on individual copy sheets, it can consist of a small amount of a dissolved dye or pigment contained in a wax binder. For the inscription of hectographic transfer printing originals, the transfer layer can consist of large amounts of an undissolved, finely divided hectographic dye which is contained in a wax binder or a resinous binder. Oleophilic transfer layers, preferably made of wax which is slightly colored for proofreading purposes, are used for writing on planographic printing plates made of paper or plastic films.

The heat transferable coatings or layers according to the invention are essentially free of infrared radiation absorbing substances and are applied to thin carrier films in the form of extremely thin layers, preferably with a thickness of only about 5 to about 15 μ.

The invention can be modified widely without departing from its scope will.

Claims (7)

Patent claims: 1. Thermal copying process in which a copy sheet absorbs infrared radiation Sheet carrying original image locations and an ink transfer sheet are folded so that the ink layer of the ink transfer sheet is in surface contact with the copy sheet and melts on infrared exposure at the locations corresponding to the original image locations and merges onto the copy sheet, characterized in that an ink transfer sheet with a plastic carrier film used, which is on one or both surfaces a thin, non-infrared absorbent material, antistatic, above 49 ° C melting coating. 2. The method according to claim 1, characterized in that a carrier film is used in which the thin antistatic coating is applied to the surface of the plastic carrier which is opposite the side bearing the heat transferable imaging layer. 3. The method according to claim 1 or 2, characterized in that an antistatic coating containing an antistatic agent dispersed in a film-forming binder is used. 4. The method according to any one of the preceding claims, characterized in that a thin, antistatic coating with a melting point not below 93 ° C is used. 5. The method according to claim 3, characterized in that an antistatic coating is used which contains ethyl cellulose as a film-forming binder. 6. The method according to any one of the preceding claims, characterized in that as flexible sheet a hectographic transfer printing original and as a heat transferable, image-generating one Layer a hectographic dye layer is used. 7. The method according to any one of the preceding claims, characterized in that as flexible sheet a planographic printing plate and for the heat transferable, imaging layer oleophilic, image-forming substance is used. 709 718/368 12.67 © Bundesdruckerei Berlin