CA1190987A - Process and compositions for printing in multiple layers - Google Patents
Process and compositions for printing in multiple layersInfo
- Publication number
- CA1190987A CA1190987A CA000454979A CA454979A CA1190987A CA 1190987 A CA1190987 A CA 1190987A CA 000454979 A CA000454979 A CA 000454979A CA 454979 A CA454979 A CA 454979A CA 1190987 A CA1190987 A CA 1190987A
- Authority
- CA
- Canada
- Prior art keywords
- varnish
- hiding
- ink
- coat
- formulation
- 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
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
- B41M3/005—Colour cards; Painting supports; Latent or hidden images, e.g. for games; Time delayed images
Landscapes
- Inks, Pencil-Leads, Or Crayons (AREA)
- Paints Or Removers (AREA)
Abstract
ABSTRACT
Printed materials such as tickets, lottery forms, cards and contest forms, bearing a hidden message which is revealable by scratching off a covering opaque layer, are prepared by printing, preferably lithographically, a message with a dark coloured pigmented varnish-ink, covering the printed message with another layer of differently coloured varnish-ink and then printing i.e. lithographically a hiding coat over the pigmented varnish-ink layer. The pigmented varnish ink formulation and the hiding coat layer are both based upon compatible, preferably the same, film-forming resin systems and are deposited from a common solvent.
Printed materials such as tickets, lottery forms, cards and contest forms, bearing a hidden message which is revealable by scratching off a covering opaque layer, are prepared by printing, preferably lithographically, a message with a dark coloured pigmented varnish-ink, covering the printed message with another layer of differently coloured varnish-ink and then printing i.e. lithographically a hiding coat over the pigmented varnish-ink layer. The pigmented varnish ink formulation and the hiding coat layer are both based upon compatible, preferably the same, film-forming resin systems and are deposited from a common solvent.
Description
This invention relates to printing methods and printing ink compositions. More particularly, it relates to methods and compositions for making sheets such as paper sheets or cards covered with superimposed layers of print, the lower of which comprises a "hidden" message which is masked from a reader unless an~ until an upper coating is removed, e.g. by abrasion, scratching and erasures.
Recently, the preparation and distribution of promotional game cards, premium cards, lottery tickets and the like, containing hidden messages or symbols has become popular and widespread, in fund raising and product promotion. The recipient of such a card must remove from the card a layer of hiding coating in order to reveal a message or symbol. Such items are, however, difficult to prepare and print in an economical fashion, because of the technical specifications they must fulfil.
Such a card bearing a hidden message normally has at least two coating layers overlying a hidden message.
Imme~iately over the message, a transparent or translucent protective layer is provided, through which the message can be read. Over the protective layer, an opaque second layer is applied in order to hide the message. The hiding layer can be subsequently stripped away e.g. by scratching etc., to reveal the message through the first coat.
It is necessary that there exists, as between the protective coat or layer and the hiding coat or layer an acceptable degree of adhesion or affinity, so that the hiding
Recently, the preparation and distribution of promotional game cards, premium cards, lottery tickets and the like, containing hidden messages or symbols has become popular and widespread, in fund raising and product promotion. The recipient of such a card must remove from the card a layer of hiding coating in order to reveal a message or symbol. Such items are, however, difficult to prepare and print in an economical fashion, because of the technical specifications they must fulfil.
Such a card bearing a hidden message normally has at least two coating layers overlying a hidden message.
Imme~iately over the message, a transparent or translucent protective layer is provided, through which the message can be read. Over the protective layer, an opaque second layer is applied in order to hide the message. The hiding layer can be subsequently stripped away e.g. by scratching etc., to reveal the message through the first coat.
It is necessary that there exists, as between the protective coat or layer and the hiding coat or layer an acceptable degree of adhesion or affinity, so that the hiding
- 2 - ~
coat remains in place and opaque to hide the message during storage, shippi~g, packaging, and transportation of the cards~
Nevertheless, the hiding coat ("scratch off coat") must be readily removable by abrasion by the user at the required time, to render the message visible, leaving the first coat substantially unaffected.
In the process according to the present invention, the compositions may be applied lithographically, by letterpress, web or dry offset or heat set techniques. The preferred process is lithography. Adaptations of the ink compositions discussed herein to suit the particular method of application will be apparent to the skilled artisan.
The present invention provides a process, and composition for use therein, whereby the hidden message and other printed material are applied to the stock on a pigmented, specifically formulated varnish-ink composition. The film-forming resin system of the varnish-ink composition and that of the hiding coat composition are substantially compatible with one another. They are preferably deposited from a commmon or at least mutually compatible solvent vehicle.
The present invention provides an improved process for preparing printed or coated cards or similar items bearing messages hidden under an opaque layer, by providing a formulation which contains both pigment usable in printing of a visible message on a substrate and varnish for the protection of the message from abrasion and for compatibility with the hiding layer whose base or vehicle is mutually compati~le with that of the fvrmulated varnish-ink composition.
In the preferred process of the present invention~ both the varnish-ink composition and the hiding coat may be applied to the card lithographically. To facilitate this, the pigmented varnish-ink coat formulation and the hiding coat formulation are deposited from compatible solvent systems and contain mutually compatible resin systems. Then the hiding coat, containing -~
opacifying pigments, can be applied as a thin layer, suitably formulated to be applied by lithography, and still exhibit the necessary hidiny power whilst being abrasively removable. ~n addition, if desired, further patterns can be applied over the hiding coat.
Previously proposed hiding coats have had to be deposited by silk-screen methods in order to adhere satisfactorily to the protective coat. This is inconvenient and expensive, since it requires the use of different printing machinery from that used to apply the other printing layers.
The pigmented varnish-ink formulation and the hiding coat formulation of the present invention have film-forming resin systems which are mutually compatible. Preferably they comprise generally the same resins or types of resins in both formulations.
Examples of suitable resins for use in both the pigmented varnish-ink and the hiding coat formulation are phenolic resins such as phenolic modified rosin esters, hydrocarbon resins, alkyd resins such as linseed-isophthalic alkyd and other unsaturated alkyds resins and the like, and mixtures thereof. Such resin systems are curable with heavy metal-organic salts such as manganese octoate and cobalt octoate, to yield light coloured or transparent films. They can be plasticised i~ desired, e.g. with waxes of the hydrocarbon type. The pigmented varnish-ink formulation may contain other ingredients in minor proportions to modify its surEace properties. For example, small amounts of Montan wax, Carnuaba -wax or another natural or synthetic wax of similar characteristics, can be added to give a harder surface finish.
Such a wax component may in fact migrate to the surface of the coating after curing ("bloom") and then contribute to the surface characteristics of the layer. The hiding coat formulation should include a drying oil such as refined linseed oil, and smaller amounts of curative, along with opacifying agents, to yield a film of suitable hiding qualities and compatibility with the pigmented varnish-ink film, yet readily abrasively removable therefrom.
As noted, both the pigmented varnish-ink formulation and the hiding coat formulation should be deposited from compatible solvent systems, preferably from the same solvent system. Hydrocarbon solvents (e.g. Magie oil, a mixture of aliphatic and aromatic oils) are preferred. The pigmented varnish-ink formulation will normally contain substantially large proportions of solvent, and hence be of substantially thinner consistency, than the hiding coat formulation. Both formulations are nevertheless of a suitable consistency for application preferably by lithography. The solvent used for the hiding coat shGuld not be capable of penetrating the cured ~L9~87 pigmented varnish-ink coat to any significant extent, despite the fact that the very same solvent may well have constituted the vehicle for deposition of the uncured pigmented varnish-ink. Accordingly, a fast drying varnish system is chosen, which cures to a hard ~inish to prevent solvent and pigment penetration thereof from the hiding coat, but which nevertheless "traps" the subsequently applied hiding coat to the necessary degree.
In order to be satisfactory for lithographic application, an ink formulation must be adjusted in relation to the printing machine speed, to adjust its rate of drying and curing. On a high speed machine, the amount of heat generated by the machine may cure the pigmented varnish-ink to such an extent that the applied layer will not transfer from the plate cylinder to the rubber blanket cylinder and on down the roller train. Accordingly, depending upon the speed and nature of the lithographic printing machine by means of which the pigmented varnish-ink is to be applied, it may be necessary to retard the drying or hardening rate of the pigmented varnish-ink as compared with normal varnishes. When a slower speed of machine is employed, such retardation may not be necessary.
With regard to the curing and the drying of the pigmented varnish-ink, it has additionally been found that the pigmented varnish-ink can be cured in a minimum amount of time.
Curing and drying of a pigmented varnish under an infra red energy source can be completed in as little as 30 minutes. This t7 provides additional time savings for operations of this type.
In the preferred process according to the present invention, the card or paper stock is initially printed, in a first colour, with the indicia to be subsequently covered with the "scratch-off" hiding coat (the "hidden message") at the appropriate location, lithographically. At the same tiDle and from the same plate, any other areas of the stock may be appropriately printed with the same colour, e.g. with text, picture, design, etc. Normally, the first colour will be the darkest colour to be applied, e.g. hlack or dark blue. The ink composition used for the first lithographic applica~ion step may be of the composition according to the invention, i.e. a varnish-ink, or a standard conventional lithographic ink suited to the base stock.
In the next step of the preferred process, the stock is overprinted lithographically with a second colour, of a varnish-ink according to the invention, at least in the area of the "hidden message" t as a solid block covering it. This second colour may be applied wet-on-wet over the first colour.
Preferably it is restricted to cover only the area of the "hidden message", but may if desired be used to apply additional text or colour to other are~s o~ the stock. Red is a suitable choice for the second colour. The "hidden message" is still readable through the applied second coat.
There then follow optional steps of lithographic application of additional colour, to complete the printing of the stock. If it is required to produce full-colour printing on the stock, e.g~ with full colour illustration, two more colours, e.g. green and yellow, are applied successively, wet-on-wet, over the second colour by lithographic means~ Thus a standard four-colour lithographic printing machine can be used. If any of the subsequently applied colours are to cover the "hidden message", t~en the composition of such colour must be a varnish-ink according to the present invention. It is however preferred to avoid further coating of the "hidden message" with the subsequently applied colours, so tnat they catl be formulated according to standard lithographic ink formulation, compatible with the stock and the previously ap~lied coats. It ls however to be emphasized that the third and fourth colour applications are optional and not essential to the successful practice of the process of the invention.
After the desired number of colour coats have been thus lithographically applied, the printed stock is allowed to dry, and then the scratch-off hiding coat is applied lithographically to the "hidden message" area. Drying of the colour coats normally takes from 6 to 24 hours, so that the hiding coat application is conveniently conducted the following day. The hiding coat, of formulation previously described, is lithographically applied over the "hidden message" area, in one, two or three wet-on-wet applications using a standard lithographic plate and printlng machine. Then the hiding coat is dried. It is found that the hidin~ coat successsfuly adheres to the coating over the "hidden message" so as to render it indecipherable, and is sufficiently adhesive and durable to withstand normal handling and transporation of the printed stock. Nevertheless it can be readily scratched off, to reveal the "hidden message" throuc~h the coating of the second colour.
The varnish which, along with any desired pigment, is used to formulate the pigmented varnish-ink of the present invention, is preferably as follows, the ingredients being expressed as percentaqes by weight:
Components % Ran~e Magie oil (solvent) 30-35 Phenolic modified rosin ester 16-20 Hydrocarbon resin (e.g. of the PICCOPALE* type) 13-17 Linseed-isophthalic alkyd 10-13 Hydrocarbon plasticizer (e.g. of the DUTREX* type) 7-10 Montan wax 3-6 Calcium perborate 1.5-3 Manganese octoate 1.5-2 Cobalt octoate 0.5-1 Gelling agent 0.5-0.7 Chinawood oil 0.3-0~5 *Trade mark In this formulation, cobalt octoate, manganese octoate and calcium perborate constitute the curing system. The calcium perborate helps to cure the chinawood oil~ by supplying oxygen thereto. Similar hydrocarbon flexibilizer may be used in place of DUTREX as the plasticizer. Also similar hydeocarbon rosins may be used in place of PICCOPALE. The chinawood oil (tung oil) is optionally added, to adjust the consistency and taclciness o~
the surface. The gelling agent also adjusts the consistency of the formulation. As gelling agent, there can be used any suitable product from the reaction of an unsaturated fat~ty acid, a solvent and calcium octoate. Alternatively, thickeners such as fumed silica may be used as or instead of a gelLing agent.
In order to formulate the pigmented varnish of the present invention for application by lithography 15-25% of the normal pigment (ink) vehicle usually employed in lithographic printing, is substituted by the varnish identified above. The varnish may be substituted in any colour of ink in order to formulate the pigmented varnish. In this way, a large number o~
colours may be used to print the message and any other pattern required on the card. A number of layers of differently coloured pigmented varnishes may be applied in succession, in order to print a multi-coloured pattern and/or message on the card. It is, of course, necessary that in such cases, the colour of the second layer and any additional layer be chosen so as to maintain visibility of the message printed by the first layer.
Formulation of the pigmented varnish of the present invention for use with other printing methods may require incorporation into the varnish identified above, of inks which are typically used in those printing methods.
In formulating the pigmented varnish, the extent of the varnish substitution for normal ink vehicle is dependent on the colour sequence used in the printing process. It is most desirable that the uppermost layer of piqmented varnish contains a higher percentage of the varnish than the lower layers so as to provide optimum communication between the pigmented varnish and the hiding layer.
The following is a preferred general formulation for the pigmented varnish-ink for lithographic use in the present invention. The amollnts of ingredients are expressèd as parts by weight:
Components % Range Magiè oil (paraffin based solvent) 20-28 Phenolic modified rosin ester 14-18 Hydrocarbon resin (e.g. of the PICCOPALE* type) 8-12 Linseed-isophthalic alkyd 6-10 Hydrocarbon plasticizer ~e.g. of the DUTREX* type) 6-8 Isophorone diamine 0.5-105 Texanol isobutyrate 2-5 Montan wax 2-5 Calcium perborate 1 5 Manganese octoate 1-2 Cobalt octoate 0.5-1 Gelling agent 0.3-0.6 Chinawood oil 0~3-0-5 Pigment 16-25 *Trade mark a8~
It should be noted that the pigmented varnish may also be prepared by mixing known inks of desired colour directly with the varnish. In this case, it will be evident that dilution of the pigment will result. Additional pigment may be added to retrieve the original intensity of the ink, if desired.
Preferably, the hiding coat contains pigments or opacifying agents which render the finished coat not only visibly opaque but also opaque to all other forms and wavelengths of radiation also, so that the "hidden message"
cannot be prematurely revealed e.g. by ~-rays, UV lic3ht etc.
For this purpose the hiding coat formulation should contain a powdered metal such as powdered aluminum, carbon ~lack, dyes etc.
A suitable such hiding coat for use by lithographic application is as follows, with the amounts of ingredients expressed as percentages by weight:
Components ~ Ran~e Titanium dioxide 28-35 Aluminum powder 15-~0 Phenolic modified resin ester 15-18 Linseed oil refined 9-11 ~lack pigment (carbon black) 7-8 Linseed-isophthalic alkyd 5-8 Magie solvent 5_7 Cobalt octoate 0.5-1 Chinawood oil 0.5-1 Hydrocarbon resin 0.5-1 Polyethylene wax 0.3-0.5 Fischer-Tropsch wax 0.2-0.5 Gelling agent 0.5-1 The hiding coat formulations for use in the present invention may be the same as described above or may contain an additional ingredient. It has been found that incorporation of one or more species of long chain fatty amides, of which may be mentioned erucamicle, erucyl stearamide and erucyl erucamide, will improve the scratch-off properties of the hidng coat without impairing its integrity durin~ the normal handling and storage. Incorporation of the long chain fatty amides with the above mentioned hiding coat formulation in a preferred range of about 10-20% by weight has been found to provide easier removal thereof by abrasion by the user and improved clarity oE the uncovered message.
It will be noted that the above hiding coat formulation has the same basic resin system and solvent as the pigmented varnish-ink formulation. It differs, however, in the amount of solvent and hence consistency, in the amount of curing system, and in the presence of opacifying agents of those mentioned in the specific formulations. Other suitable unsaturated oils may be used instead of linseed oil, and instead of chinawood oil.
The gelling agent is as described in connection with the pigmented varnish-ink coat. The presence of some such unsaturated oil is high~y advantageous in providing the best "scratch-off" properties. The linseed-isophthalic alkyd resin in both formulations is ~ 13 -8'7 represented in a large variety of available such materials, and substantially any other unsaturated alkyd could be used instead. IsophthaLics are preferred, however.
The pigmented varnish-ink coat is suitably applied to a printed card stock by sheet fed or web lithograph methods. The aforementioned formulations are most suitable for sheet fed -lithography. The consistency of the formulations needs adjustment to render them more suitable for web lithography.
The pigmented varnish-ink layees, suitably 2-4 in number, wherein each layer may be the same or a different colour, may be applied wet-on-wet, i.e. without waiting for the previously applied layer of pigmented varnish to dry and cure.
The total pigmented varnish coat must however, as mentioned, be dried and cured before the hiding coat is applied. Then the hiding coat is also suitably applied to the stock, over the pigmented varnish, in one or several wet-on-wet layers, and then allowed to dry and cure.
The resulting hiding coat is durable not only to withstand normal storage and handling, but also to receive further overprintings with additional hiding layers, patterns or printed information, should this be required. The scratch-off portion can be readily removed by the user's fingernails9 without abrasives, coins, files, erasers or the like, to show clearly the overprinted hidden messageO
The invention is further illustrated in the following specific examples.
Example 1:
The following specific pigmented varnish-ink formulatlon (a red ink) and hiding coat formulation were made up, with ingredients listed as weight percentages:
RED VARNISH-INK FORMULATION
Components ~_Ran~e Magie oil (paraffin based solvent) 25 Phenolic modified rosin ester 15 Hydrocarhon resin (e.g. of the PICCOP~LE* type) 14 Linseed-isophthalic alkyd 8 Hydrocarbon plasticizer (e.g. of the DUTREX* type) 6 Isophorone diamine Texanol isobutyrate 4 Montan wax 3 Calcium perborate 2.2 Manganese octoate 0.3 Cobalt octoate 0.5 Gelling agent 0,5 Chinawood oil 0.5 Pigment (Permanent Carmine FBB02 (CI, 12485) 20 *Trade mark '7 HIDING COAT FORMULATION
~ onents Titanium dioxide (TIOXIDE*~ 32 Aluminum powder 18 PhenoLic modified resin ester 16 I.inseed oil refined 10 Black pigment ~carbon black) L,.inseed-isophthalic alkyd 5 Magie solvent 6 Cobalt octoate 0.6 Chinawood oil 0.6 Hydrocarbon resin (PICCOPALE type) Polyethylene wax 0.3 Fischer-Tropsch wax 0~3 Gelling agent 0.6 * Trade Mark The red varnish-ink formulation was applied, by sheet fed lithographically using a standard printing machine, to a card stock bearing indicia previously printed with a standard black ink known for use in lithographic printing. The card contained an area with a printed message which was to be hidden. The carmine pigmented ink formulation was applied lithographically over the message area such that the entire , ~, message was covered by a solid rectangular block of the red varnish-ink~ The message was clearly visible and legible through the red varnish-ink coat. The applied red varnish-ink coat was allowed to dry and cure for one day.
Next, using the same sheet fed lithographic printing machine, the hiding coat was applied directly over the cured varnish-ink coat. Four layers were applied, wet on wet, and then the hiding coat was allowed to dry.
The hiding coat so formed completely obliterated the underlying message. It was durable enough to withstand normal handling and packaging. Nevertheless, it was removable by scratching with a fingernail, to reveal the varnish coat substantially unaffected, through which the printed message was clearly visible.
By replacing the carmine pigment component in the varnish-ink formulation o example 1, black pigmented, yellow pigmented, and blue pigmented varnish-ink were prepared. The carmine varnish-ink was also prepared as per example 1.
Using the black-pigmented varnish-ink, a first layer was printed on a black substrate by a sheet-fed lithographic press having four printing stations in serial arrangement. This first black layer marked characters on the blank substrate including the indicia which were to be hidden, i.e. the "message".
The indicia-bearing substrate was passed, while still "wet" to a second pressing station on the same lithographic press where the carmine pigmented varnish-ink was applied such that the entire area encompassing the message was covered or "masked by the carmine ink-varnish. Other areas were printed on the substrate at this same station and with the same carmine pigmented varnish ink in this printing step in order to add colour to the characters on the card outside the area containing the message. The masking provides a surface over the message which enables the hiding layer to be reversibly trapped within the area of the maskin~. The message was clearly vislble and legible through the carmine layer.
A third layer of yellow-pigmented varnish-ink was then applied at the next station on the same lithographic press to the substrate on areas outside of the message area. This additiona] layer served to add colur to the characters on the face of the card.
To provide an even more colourful card the substrate was passed from the yellow-pigmented printing station to the fourth and final printing station on the press where the blue-pigmented varnish-ink was appropriately layered on areas outside the message area.
Although it is within the scope of the invention to apply either or both of the yellow and blue-pigmented varnishes into the masked area at the subsequent printing stations it will be realized that, since the carmine layer i.e. the first masking layer will fulfill the aforementioned requirements of releasably trapping the hiding layer, savings on ink consumed in the printing process can be obtained by omitting the application of more than one b1ocking layer.
After the final fourth layer was printed, the substrate was removed and allowed to cure until the next day. Means for reducing the curing time can be used to accelerate the curing~ --process, if desired, such as an infra red energy source, etc.
The substrate with the cured varnish-ink layers was then introduced into a lithoc3raphic press having, agaill, four printing stations, each oE which contained a hiding coat formulation as e~emplified in example 1~ The hiding coat was applied directly over the carmine pigmented area blocking the message at each successive station.
The layers were applied wet-on-wet. After passing through the press the card was removed and allowed to dry.
The following day, it was found that the hiding coat layer was completely removeable to reveal the hidden message by scratching with a fingernail.
Whilst according to the invention, it is preferred to apply the varnish coat and the hiding coat lithographically, it is nevertheless possible to apply the varnish-ink coat by letterpress application or by other methods kno~n in the art and the hiding coat lithographically, thus providing the advantage, of avoiding silk screen application. In application by -letterpress, the hydrocarbon rosin component is omitted from the varnish-ink formulation.
coat remains in place and opaque to hide the message during storage, shippi~g, packaging, and transportation of the cards~
Nevertheless, the hiding coat ("scratch off coat") must be readily removable by abrasion by the user at the required time, to render the message visible, leaving the first coat substantially unaffected.
In the process according to the present invention, the compositions may be applied lithographically, by letterpress, web or dry offset or heat set techniques. The preferred process is lithography. Adaptations of the ink compositions discussed herein to suit the particular method of application will be apparent to the skilled artisan.
The present invention provides a process, and composition for use therein, whereby the hidden message and other printed material are applied to the stock on a pigmented, specifically formulated varnish-ink composition. The film-forming resin system of the varnish-ink composition and that of the hiding coat composition are substantially compatible with one another. They are preferably deposited from a commmon or at least mutually compatible solvent vehicle.
The present invention provides an improved process for preparing printed or coated cards or similar items bearing messages hidden under an opaque layer, by providing a formulation which contains both pigment usable in printing of a visible message on a substrate and varnish for the protection of the message from abrasion and for compatibility with the hiding layer whose base or vehicle is mutually compati~le with that of the fvrmulated varnish-ink composition.
In the preferred process of the present invention~ both the varnish-ink composition and the hiding coat may be applied to the card lithographically. To facilitate this, the pigmented varnish-ink coat formulation and the hiding coat formulation are deposited from compatible solvent systems and contain mutually compatible resin systems. Then the hiding coat, containing -~
opacifying pigments, can be applied as a thin layer, suitably formulated to be applied by lithography, and still exhibit the necessary hidiny power whilst being abrasively removable. ~n addition, if desired, further patterns can be applied over the hiding coat.
Previously proposed hiding coats have had to be deposited by silk-screen methods in order to adhere satisfactorily to the protective coat. This is inconvenient and expensive, since it requires the use of different printing machinery from that used to apply the other printing layers.
The pigmented varnish-ink formulation and the hiding coat formulation of the present invention have film-forming resin systems which are mutually compatible. Preferably they comprise generally the same resins or types of resins in both formulations.
Examples of suitable resins for use in both the pigmented varnish-ink and the hiding coat formulation are phenolic resins such as phenolic modified rosin esters, hydrocarbon resins, alkyd resins such as linseed-isophthalic alkyd and other unsaturated alkyds resins and the like, and mixtures thereof. Such resin systems are curable with heavy metal-organic salts such as manganese octoate and cobalt octoate, to yield light coloured or transparent films. They can be plasticised i~ desired, e.g. with waxes of the hydrocarbon type. The pigmented varnish-ink formulation may contain other ingredients in minor proportions to modify its surEace properties. For example, small amounts of Montan wax, Carnuaba -wax or another natural or synthetic wax of similar characteristics, can be added to give a harder surface finish.
Such a wax component may in fact migrate to the surface of the coating after curing ("bloom") and then contribute to the surface characteristics of the layer. The hiding coat formulation should include a drying oil such as refined linseed oil, and smaller amounts of curative, along with opacifying agents, to yield a film of suitable hiding qualities and compatibility with the pigmented varnish-ink film, yet readily abrasively removable therefrom.
As noted, both the pigmented varnish-ink formulation and the hiding coat formulation should be deposited from compatible solvent systems, preferably from the same solvent system. Hydrocarbon solvents (e.g. Magie oil, a mixture of aliphatic and aromatic oils) are preferred. The pigmented varnish-ink formulation will normally contain substantially large proportions of solvent, and hence be of substantially thinner consistency, than the hiding coat formulation. Both formulations are nevertheless of a suitable consistency for application preferably by lithography. The solvent used for the hiding coat shGuld not be capable of penetrating the cured ~L9~87 pigmented varnish-ink coat to any significant extent, despite the fact that the very same solvent may well have constituted the vehicle for deposition of the uncured pigmented varnish-ink. Accordingly, a fast drying varnish system is chosen, which cures to a hard ~inish to prevent solvent and pigment penetration thereof from the hiding coat, but which nevertheless "traps" the subsequently applied hiding coat to the necessary degree.
In order to be satisfactory for lithographic application, an ink formulation must be adjusted in relation to the printing machine speed, to adjust its rate of drying and curing. On a high speed machine, the amount of heat generated by the machine may cure the pigmented varnish-ink to such an extent that the applied layer will not transfer from the plate cylinder to the rubber blanket cylinder and on down the roller train. Accordingly, depending upon the speed and nature of the lithographic printing machine by means of which the pigmented varnish-ink is to be applied, it may be necessary to retard the drying or hardening rate of the pigmented varnish-ink as compared with normal varnishes. When a slower speed of machine is employed, such retardation may not be necessary.
With regard to the curing and the drying of the pigmented varnish-ink, it has additionally been found that the pigmented varnish-ink can be cured in a minimum amount of time.
Curing and drying of a pigmented varnish under an infra red energy source can be completed in as little as 30 minutes. This t7 provides additional time savings for operations of this type.
In the preferred process according to the present invention, the card or paper stock is initially printed, in a first colour, with the indicia to be subsequently covered with the "scratch-off" hiding coat (the "hidden message") at the appropriate location, lithographically. At the same tiDle and from the same plate, any other areas of the stock may be appropriately printed with the same colour, e.g. with text, picture, design, etc. Normally, the first colour will be the darkest colour to be applied, e.g. hlack or dark blue. The ink composition used for the first lithographic applica~ion step may be of the composition according to the invention, i.e. a varnish-ink, or a standard conventional lithographic ink suited to the base stock.
In the next step of the preferred process, the stock is overprinted lithographically with a second colour, of a varnish-ink according to the invention, at least in the area of the "hidden message" t as a solid block covering it. This second colour may be applied wet-on-wet over the first colour.
Preferably it is restricted to cover only the area of the "hidden message", but may if desired be used to apply additional text or colour to other are~s o~ the stock. Red is a suitable choice for the second colour. The "hidden message" is still readable through the applied second coat.
There then follow optional steps of lithographic application of additional colour, to complete the printing of the stock. If it is required to produce full-colour printing on the stock, e.g~ with full colour illustration, two more colours, e.g. green and yellow, are applied successively, wet-on-wet, over the second colour by lithographic means~ Thus a standard four-colour lithographic printing machine can be used. If any of the subsequently applied colours are to cover the "hidden message", t~en the composition of such colour must be a varnish-ink according to the present invention. It is however preferred to avoid further coating of the "hidden message" with the subsequently applied colours, so tnat they catl be formulated according to standard lithographic ink formulation, compatible with the stock and the previously ap~lied coats. It ls however to be emphasized that the third and fourth colour applications are optional and not essential to the successful practice of the process of the invention.
After the desired number of colour coats have been thus lithographically applied, the printed stock is allowed to dry, and then the scratch-off hiding coat is applied lithographically to the "hidden message" area. Drying of the colour coats normally takes from 6 to 24 hours, so that the hiding coat application is conveniently conducted the following day. The hiding coat, of formulation previously described, is lithographically applied over the "hidden message" area, in one, two or three wet-on-wet applications using a standard lithographic plate and printlng machine. Then the hiding coat is dried. It is found that the hidin~ coat successsfuly adheres to the coating over the "hidden message" so as to render it indecipherable, and is sufficiently adhesive and durable to withstand normal handling and transporation of the printed stock. Nevertheless it can be readily scratched off, to reveal the "hidden message" throuc~h the coating of the second colour.
The varnish which, along with any desired pigment, is used to formulate the pigmented varnish-ink of the present invention, is preferably as follows, the ingredients being expressed as percentaqes by weight:
Components % Ran~e Magie oil (solvent) 30-35 Phenolic modified rosin ester 16-20 Hydrocarbon resin (e.g. of the PICCOPALE* type) 13-17 Linseed-isophthalic alkyd 10-13 Hydrocarbon plasticizer (e.g. of the DUTREX* type) 7-10 Montan wax 3-6 Calcium perborate 1.5-3 Manganese octoate 1.5-2 Cobalt octoate 0.5-1 Gelling agent 0.5-0.7 Chinawood oil 0.3-0~5 *Trade mark In this formulation, cobalt octoate, manganese octoate and calcium perborate constitute the curing system. The calcium perborate helps to cure the chinawood oil~ by supplying oxygen thereto. Similar hydrocarbon flexibilizer may be used in place of DUTREX as the plasticizer. Also similar hydeocarbon rosins may be used in place of PICCOPALE. The chinawood oil (tung oil) is optionally added, to adjust the consistency and taclciness o~
the surface. The gelling agent also adjusts the consistency of the formulation. As gelling agent, there can be used any suitable product from the reaction of an unsaturated fat~ty acid, a solvent and calcium octoate. Alternatively, thickeners such as fumed silica may be used as or instead of a gelLing agent.
In order to formulate the pigmented varnish of the present invention for application by lithography 15-25% of the normal pigment (ink) vehicle usually employed in lithographic printing, is substituted by the varnish identified above. The varnish may be substituted in any colour of ink in order to formulate the pigmented varnish. In this way, a large number o~
colours may be used to print the message and any other pattern required on the card. A number of layers of differently coloured pigmented varnishes may be applied in succession, in order to print a multi-coloured pattern and/or message on the card. It is, of course, necessary that in such cases, the colour of the second layer and any additional layer be chosen so as to maintain visibility of the message printed by the first layer.
Formulation of the pigmented varnish of the present invention for use with other printing methods may require incorporation into the varnish identified above, of inks which are typically used in those printing methods.
In formulating the pigmented varnish, the extent of the varnish substitution for normal ink vehicle is dependent on the colour sequence used in the printing process. It is most desirable that the uppermost layer of piqmented varnish contains a higher percentage of the varnish than the lower layers so as to provide optimum communication between the pigmented varnish and the hiding layer.
The following is a preferred general formulation for the pigmented varnish-ink for lithographic use in the present invention. The amollnts of ingredients are expressèd as parts by weight:
Components % Range Magiè oil (paraffin based solvent) 20-28 Phenolic modified rosin ester 14-18 Hydrocarbon resin (e.g. of the PICCOPALE* type) 8-12 Linseed-isophthalic alkyd 6-10 Hydrocarbon plasticizer ~e.g. of the DUTREX* type) 6-8 Isophorone diamine 0.5-105 Texanol isobutyrate 2-5 Montan wax 2-5 Calcium perborate 1 5 Manganese octoate 1-2 Cobalt octoate 0.5-1 Gelling agent 0.3-0.6 Chinawood oil 0~3-0-5 Pigment 16-25 *Trade mark a8~
It should be noted that the pigmented varnish may also be prepared by mixing known inks of desired colour directly with the varnish. In this case, it will be evident that dilution of the pigment will result. Additional pigment may be added to retrieve the original intensity of the ink, if desired.
Preferably, the hiding coat contains pigments or opacifying agents which render the finished coat not only visibly opaque but also opaque to all other forms and wavelengths of radiation also, so that the "hidden message"
cannot be prematurely revealed e.g. by ~-rays, UV lic3ht etc.
For this purpose the hiding coat formulation should contain a powdered metal such as powdered aluminum, carbon ~lack, dyes etc.
A suitable such hiding coat for use by lithographic application is as follows, with the amounts of ingredients expressed as percentages by weight:
Components ~ Ran~e Titanium dioxide 28-35 Aluminum powder 15-~0 Phenolic modified resin ester 15-18 Linseed oil refined 9-11 ~lack pigment (carbon black) 7-8 Linseed-isophthalic alkyd 5-8 Magie solvent 5_7 Cobalt octoate 0.5-1 Chinawood oil 0.5-1 Hydrocarbon resin 0.5-1 Polyethylene wax 0.3-0.5 Fischer-Tropsch wax 0.2-0.5 Gelling agent 0.5-1 The hiding coat formulations for use in the present invention may be the same as described above or may contain an additional ingredient. It has been found that incorporation of one or more species of long chain fatty amides, of which may be mentioned erucamicle, erucyl stearamide and erucyl erucamide, will improve the scratch-off properties of the hidng coat without impairing its integrity durin~ the normal handling and storage. Incorporation of the long chain fatty amides with the above mentioned hiding coat formulation in a preferred range of about 10-20% by weight has been found to provide easier removal thereof by abrasion by the user and improved clarity oE the uncovered message.
It will be noted that the above hiding coat formulation has the same basic resin system and solvent as the pigmented varnish-ink formulation. It differs, however, in the amount of solvent and hence consistency, in the amount of curing system, and in the presence of opacifying agents of those mentioned in the specific formulations. Other suitable unsaturated oils may be used instead of linseed oil, and instead of chinawood oil.
The gelling agent is as described in connection with the pigmented varnish-ink coat. The presence of some such unsaturated oil is high~y advantageous in providing the best "scratch-off" properties. The linseed-isophthalic alkyd resin in both formulations is ~ 13 -8'7 represented in a large variety of available such materials, and substantially any other unsaturated alkyd could be used instead. IsophthaLics are preferred, however.
The pigmented varnish-ink coat is suitably applied to a printed card stock by sheet fed or web lithograph methods. The aforementioned formulations are most suitable for sheet fed -lithography. The consistency of the formulations needs adjustment to render them more suitable for web lithography.
The pigmented varnish-ink layees, suitably 2-4 in number, wherein each layer may be the same or a different colour, may be applied wet-on-wet, i.e. without waiting for the previously applied layer of pigmented varnish to dry and cure.
The total pigmented varnish coat must however, as mentioned, be dried and cured before the hiding coat is applied. Then the hiding coat is also suitably applied to the stock, over the pigmented varnish, in one or several wet-on-wet layers, and then allowed to dry and cure.
The resulting hiding coat is durable not only to withstand normal storage and handling, but also to receive further overprintings with additional hiding layers, patterns or printed information, should this be required. The scratch-off portion can be readily removed by the user's fingernails9 without abrasives, coins, files, erasers or the like, to show clearly the overprinted hidden messageO
The invention is further illustrated in the following specific examples.
Example 1:
The following specific pigmented varnish-ink formulatlon (a red ink) and hiding coat formulation were made up, with ingredients listed as weight percentages:
RED VARNISH-INK FORMULATION
Components ~_Ran~e Magie oil (paraffin based solvent) 25 Phenolic modified rosin ester 15 Hydrocarhon resin (e.g. of the PICCOP~LE* type) 14 Linseed-isophthalic alkyd 8 Hydrocarbon plasticizer (e.g. of the DUTREX* type) 6 Isophorone diamine Texanol isobutyrate 4 Montan wax 3 Calcium perborate 2.2 Manganese octoate 0.3 Cobalt octoate 0.5 Gelling agent 0,5 Chinawood oil 0.5 Pigment (Permanent Carmine FBB02 (CI, 12485) 20 *Trade mark '7 HIDING COAT FORMULATION
~ onents Titanium dioxide (TIOXIDE*~ 32 Aluminum powder 18 PhenoLic modified resin ester 16 I.inseed oil refined 10 Black pigment ~carbon black) L,.inseed-isophthalic alkyd 5 Magie solvent 6 Cobalt octoate 0.6 Chinawood oil 0.6 Hydrocarbon resin (PICCOPALE type) Polyethylene wax 0.3 Fischer-Tropsch wax 0~3 Gelling agent 0.6 * Trade Mark The red varnish-ink formulation was applied, by sheet fed lithographically using a standard printing machine, to a card stock bearing indicia previously printed with a standard black ink known for use in lithographic printing. The card contained an area with a printed message which was to be hidden. The carmine pigmented ink formulation was applied lithographically over the message area such that the entire , ~, message was covered by a solid rectangular block of the red varnish-ink~ The message was clearly visible and legible through the red varnish-ink coat. The applied red varnish-ink coat was allowed to dry and cure for one day.
Next, using the same sheet fed lithographic printing machine, the hiding coat was applied directly over the cured varnish-ink coat. Four layers were applied, wet on wet, and then the hiding coat was allowed to dry.
The hiding coat so formed completely obliterated the underlying message. It was durable enough to withstand normal handling and packaging. Nevertheless, it was removable by scratching with a fingernail, to reveal the varnish coat substantially unaffected, through which the printed message was clearly visible.
By replacing the carmine pigment component in the varnish-ink formulation o example 1, black pigmented, yellow pigmented, and blue pigmented varnish-ink were prepared. The carmine varnish-ink was also prepared as per example 1.
Using the black-pigmented varnish-ink, a first layer was printed on a black substrate by a sheet-fed lithographic press having four printing stations in serial arrangement. This first black layer marked characters on the blank substrate including the indicia which were to be hidden, i.e. the "message".
The indicia-bearing substrate was passed, while still "wet" to a second pressing station on the same lithographic press where the carmine pigmented varnish-ink was applied such that the entire area encompassing the message was covered or "masked by the carmine ink-varnish. Other areas were printed on the substrate at this same station and with the same carmine pigmented varnish ink in this printing step in order to add colour to the characters on the card outside the area containing the message. The masking provides a surface over the message which enables the hiding layer to be reversibly trapped within the area of the maskin~. The message was clearly vislble and legible through the carmine layer.
A third layer of yellow-pigmented varnish-ink was then applied at the next station on the same lithographic press to the substrate on areas outside of the message area. This additiona] layer served to add colur to the characters on the face of the card.
To provide an even more colourful card the substrate was passed from the yellow-pigmented printing station to the fourth and final printing station on the press where the blue-pigmented varnish-ink was appropriately layered on areas outside the message area.
Although it is within the scope of the invention to apply either or both of the yellow and blue-pigmented varnishes into the masked area at the subsequent printing stations it will be realized that, since the carmine layer i.e. the first masking layer will fulfill the aforementioned requirements of releasably trapping the hiding layer, savings on ink consumed in the printing process can be obtained by omitting the application of more than one b1ocking layer.
After the final fourth layer was printed, the substrate was removed and allowed to cure until the next day. Means for reducing the curing time can be used to accelerate the curing~ --process, if desired, such as an infra red energy source, etc.
The substrate with the cured varnish-ink layers was then introduced into a lithoc3raphic press having, agaill, four printing stations, each oE which contained a hiding coat formulation as e~emplified in example 1~ The hiding coat was applied directly over the carmine pigmented area blocking the message at each successive station.
The layers were applied wet-on-wet. After passing through the press the card was removed and allowed to dry.
The following day, it was found that the hiding coat layer was completely removeable to reveal the hidden message by scratching with a fingernail.
Whilst according to the invention, it is preferred to apply the varnish coat and the hiding coat lithographically, it is nevertheless possible to apply the varnish-ink coat by letterpress application or by other methods kno~n in the art and the hiding coat lithographically, thus providing the advantage, of avoiding silk screen application. In application by -letterpress, the hydrocarbon rosin component is omitted from the varnish-ink formulation.
Claims (15)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for removably masking indicia on a printable substrate, which comprises:
applying to the substrate and over the indicia, at least one layer of pigmented varnish-ink formulation whereby said at least one layer completely covers the area defined by said indicia, allowing said at least one layer to dry and cure to form a film overlying said indicia but through which said indicia are legible, applying at least one hiding layer over said area, allowing said at least one hiding layer to dry and cure to form an opaque, abrasion-removable mask over said area, the film-forming resin system of the pigmented varnish being substantially compatible with the film forming resin system of the hiding coat.
applying to the substrate and over the indicia, at least one layer of pigmented varnish-ink formulation whereby said at least one layer completely covers the area defined by said indicia, allowing said at least one layer to dry and cure to form a film overlying said indicia but through which said indicia are legible, applying at least one hiding layer over said area, allowing said at least one hiding layer to dry and cure to form an opaque, abrasion-removable mask over said area, the film-forming resin system of the pigmented varnish being substantially compatible with the film forming resin system of the hiding coat.
2. The process of claim 1 wherein said pigmented varnish-ink formulation is used to print said indicia on said substrate.
3. The process of claim 2 wherein the pigmented varnish-ink formulation and the hiding coat are both lithographically applied as liquid solutions or slurries in a common solvent.
4. The process of claim 3 wherein the pigmented varnish and the hiding coat include the same film forming resin system.
5. The process of claim 4 wherein the pigmented varnish and the hiding coat both include curatives for said resin system, the varnish including a larger amount of curative than the hiding coat.
6. The process of claim 5 wherein the resin system includes phenolic modified rosin ester.
7. The process of claim 4 wherein the varnish contains a wax.
8. The process of claim 7 wherein the hiding coat contains an unsaturated oil.
9. The process of claim 8 wherein the resin system also includes linseed-isophthalic alkyd resin.
The process of claim 9 wherein the hiding coat includes powdered aluminum.
11. The process of claim 10 wherein the hiding coat includes a long chain fatty amide.
12. The process of claim 11 wherein the long chain fatty amide is selected from the group consisting of erucamide, erucyl stearamide and erucyl erucamide.
13. A pigmented varnish formulation for use in lithography comprising an ink known for use in lithographic printing in admixture with a varnish of the formula:
COMPONENTS % RANGE
Ma g i e oil (solvent) 30-35 Phenolic modified rosin ester 16-20 Hydrocarbon resin 13-17 Linseed isophthalic alkyd 10-13 Hydrocarbon plasticizer 7-10 Montan Wax 3-6 Calcium perborate 1.5-3 Manganese octoate 1.5-2 Cobalt octoate 0.5-1 Gelling agent 0.5-0.7 Chinawood oil 0.3-0.5
COMPONENTS % RANGE
Ma g i e oil (solvent) 30-35 Phenolic modified rosin ester 16-20 Hydrocarbon resin 13-17 Linseed isophthalic alkyd 10-13 Hydrocarbon plasticizer 7-10 Montan Wax 3-6 Calcium perborate 1.5-3 Manganese octoate 1.5-2 Cobalt octoate 0.5-1 Gelling agent 0.5-0.7 Chinawood oil 0.3-0.5
14. The formulation of claim 13 wherein said varnish formulation is 15-25% by volume of the total volume of the pigmented varnish formulation.
15. The formulation of claim 13, or claim 14 wherein there is incorporated at least one species of long chain fatty amides selected from erucamide, erucyl stearamide and erucyl erucamide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000454979A CA1190987A (en) | 1984-05-23 | 1984-05-23 | Process and compositions for printing in multiple layers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000454979A CA1190987A (en) | 1984-05-23 | 1984-05-23 | Process and compositions for printing in multiple layers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190987A true CA1190987A (en) | 1985-07-23 |
Family
ID=4127920
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000454979A Expired CA1190987A (en) | 1984-05-23 | 1984-05-23 | Process and compositions for printing in multiple layers |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1190987A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5141562A (en) * | 1991-06-21 | 1992-08-25 | Mooney Chemicals, Inc. | Drier promoter compositions |
| US5156674A (en) * | 1991-06-21 | 1992-10-20 | Mooney Chemicals, Inc. | Drier promoter compositions |
| WO1997043126A1 (en) * | 1996-05-14 | 1997-11-20 | The British Printing Company Ltd. | Improved process for the production of scratch-off cards |
| EP1277803A1 (en) * | 2001-07-16 | 2003-01-22 | Shin-Etsu Chemical Co., Ltd. | Scratchable hiding layer-forming silicone composition |
| WO2003069549A1 (en) * | 2002-02-13 | 2003-08-21 | T.S.D. Llc | Debit card having applied personal identification number (pin) and scratch-off coating and method of forming same |
| US7682440B2 (en) | 2005-03-29 | 2010-03-23 | Genesis Ii Of Nc, Llc | Drying enhancement additive and method of using same |
| US7793590B2 (en) | 2008-05-15 | 2010-09-14 | T.S.D. Llc | System and method for forming debit card using improved print cylinder mechanism |
-
1984
- 1984-05-23 CA CA000454979A patent/CA1190987A/en not_active Expired
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5156674A (en) * | 1991-06-21 | 1992-10-20 | Mooney Chemicals, Inc. | Drier promoter compositions |
| EP0519194A2 (en) * | 1991-06-21 | 1992-12-23 | Mooney Chemicals, Inc. | Drier promoter compositions |
| EP0519194A3 (en) * | 1991-06-21 | 1993-03-03 | Mooney Chemicals, Inc. | Drier promoter compositions |
| US5141562A (en) * | 1991-06-21 | 1992-08-25 | Mooney Chemicals, Inc. | Drier promoter compositions |
| WO1997043126A1 (en) * | 1996-05-14 | 1997-11-20 | The British Printing Company Ltd. | Improved process for the production of scratch-off cards |
| US7029754B2 (en) | 2001-07-16 | 2006-04-18 | Shin-Etsu Chemical Co.,Ltd. | Scratchable hiding layer-forming silicone composition |
| EP1277803A1 (en) * | 2001-07-16 | 2003-01-22 | Shin-Etsu Chemical Co., Ltd. | Scratchable hiding layer-forming silicone composition |
| WO2003069549A1 (en) * | 2002-02-13 | 2003-08-21 | T.S.D. Llc | Debit card having applied personal identification number (pin) and scratch-off coating and method of forming same |
| US6729656B2 (en) | 2002-02-13 | 2004-05-04 | T.S.D. Llc | Debit card having applied personal identification number (PIN) and scratch-off coating and method of forming same |
| CN100354886C (en) * | 2002-02-13 | 2007-12-12 | T·S·D·有限公司 | Debit card having applied personal identification number (pin) and scratch-off coating and method of forming same |
| US7682440B2 (en) | 2005-03-29 | 2010-03-23 | Genesis Ii Of Nc, Llc | Drying enhancement additive and method of using same |
| US7793590B2 (en) | 2008-05-15 | 2010-09-14 | T.S.D. Llc | System and method for forming debit card using improved print cylinder mechanism |
| US8205552B2 (en) | 2008-05-15 | 2012-06-26 | T.S.D. Llc | System and method for forming debit card using improved print cylinder mechanism |
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