WO2000068501A1

WO2000068501A1 - Printed and printable substrates

Info

Publication number: WO2000068501A1
Application number: PCT/CH2000/000232
Authority: WO
Inventors: Jakob Grob; Thomas Leu
Original assignee: Landqart
Priority date: 1999-05-05
Filing date: 2000-04-25
Publication date: 2000-11-16
Also published as: AU3653000A; ATE269440T1; EP1180173A1; CA2372770A1; DE50006826D1; EP1180173B1

Abstract

In a printable substrate, particularly a paper-based substrate, improved printing quality, good print protection from water and frictional wear is achieved in that a support layer (12) has one print fixing layer (11) on at least one side and a film-forming organic pigment and a filmable coating (10) containing a binding agent are placed on the print fixing layer (11). The structure makes it possible to especially use low melting point organic pigments and enables simpler filming while preserving the flatness of the substrate.

Description

DESCRIPTION

TITLE

Printed and printable substrates

TECHNICAL AREA

The present invention relates to printable and printed substrates, in particular special papers, processes for their production, and their uses.

STATE OF THE ART

The majority of modern printable papers, be it for classic printing processes or for inkjet printing, have a superficial coating or impregnation, which in different dimensions for optimal adhesion of the printing ink or ink on the paper carrier, the most precise, non-blurring Localization after application, as well as lightfastness and other properties. In particular in the field of inkjet printing, special papers are used, which are provided, for example, with a coating containing inorganic pigments, among other things, to increase the color brilliance. Despite such a coating, however, aqueous inkjet prints often have low wiping and / or water resistance. Their lightfastness also leaves something to be desired.

To protect inkjet prints, especially against moisture and smudging, and to a certain extent also to increase gloss, they are often laminated with a film, for which purpose special laminators are available. Such applications can also be found in the ID or security area, often in addition a photo, passport photo or the like is "welded" into the film. However, this clever welding is hardly an obstacle to counterfeiting.

WO 97/18090 (Kimberly-Clark) describes a printable special paper which has a filmable layer arranged on a carrier material and which is intended to be filmed over a large area after printing using heat and / or pressure. The print is then essentially irreversibly bound and protected behind the film.

A special paper based on the essentially same idea is also described in DE 196 28 342 (Sihl GmbH, Düren) and EP 0 826 823 by the applicant. The carrier material and the formulation of the filmable layer are chosen in the first font so that the filmed paper is particularly resistant to the influence of water.

The specialty papers described above have a number of disadvantages. For example, the special papers have to be kept at temperatures of 140 ° C to 180 ° C for a period of 20-60s for complete filming. Such conditions can only be set with very special heating presses or with laminators of the highest price range. Furthermore, there is the problem that, in particular in the case of a one-sided filmable coating (and this is often preferred for reasons of cost), the special papers are no longer planar after the filming, or a curvature of the papers occurs during filming in the laminator and the papers therefore occasionally die Have a tendency to get stuck in the laminator.

PRESENTATION OF THE INVENTION

The object of the invention is to specify how prints, in particular inkjet prints, more abrasion-resistant, smudge-proof, water-resistant, brilliant, light-resistant and finally also more resistant can be made in the sense of increased security against forgery. The substrate should also be inexpensive to manufacture and using conventional machines.

In view of this object, the subject of the invention is a printable substrate according to claim 1 and a method for producing such a substrate according to claim 7. The invention further relates to a printed substrate according to claim 10 and a method for producing such a substrate according to claim 12.

Claims 17-19 relate to special uses of the substrates according to the invention.

The essence of the present invention is therefore to apply e.g. first apply a pressure-fixing layer from paper on at least one side, and apply a filmable coating containing organic pigments (plastic pigments) and binders to this pressure-fixing layer. This filmable coating is intended to be filmed after printing by supplying at least heat, but preferably heat and pressure. The ink penetrates into the porous filmable coating during printing, penetrates it and is bound on or in the fixing layer when the pressure fixing layer arranged between the carrier material and the filmable layer is reached. In other words, before filming, part of the ink is in the filmable layer, and the other, usually larger part of the ink is in resp. bound on the pressure fixing layer. Other printing inks, such as those used in offset processes, and which cannot penetrate into the filmable coating due to their physicochemical properties, remain essentially on the surface of the filmable coating after the printing process.

Filming the filmable layer means that the print subsequently behind or in the filmed layer is more abrasion-resistant, smudge-proof, water-resistant, brilliant and light-resistant. The use of the pressure-fixing layer means that if there is residual porosity after filming or microscopic cracks in the filmed layer, the print is still water-resistant because the pressure-fixing layer binds the ink under the film. The applied printed image appears to the viewer with increased brilliance. It has also been shown that print images produced according to the invention are substantially more lightfast than conventional inkjet prints. Additional and expensive laminations, such as are sometimes made with inkjet papers, are superfluous. Other printing inks remaining essentially on the surface after the printing process are also partially welded in by the filming and are more strongly bound. A first preferred embodiment is characterized in that the filmable coating contains the following components:

20-90% by weight, particularly preferably 70-90% by weight, of organic pigments,

1-30% by weight, particularly preferably 2-10% by weight, of binder

- 0- 20% by weight, particularly preferably 7-15% by weight, film-forming aid

- 0- 5% by weight UV stabilizers

0 - 5% by weight of oxidation stabilizers, the organic pigments having a particle size preferably in the range from 0.1 to 10 μm, more preferably in the range from 0.5 to 10 μm, particularly preferably in the range from 0.5 to 2 μm, preferably styrenes, butadienes, acrylates and their copolymers or their copolymers Combinations thereof with glass transition temperatures in the range between 40 ° C and 90 ° C, but especially between 50 ° C-70 ° C, as film-forming aids styrenes, butadienes, acrylates and their copolymers or combinations thereof with glass transition temperatures below room temperature, but especially between (-50 ° C) - (+ 20 ° C), and the binder used is preferably starch, polyvinyl alcohol, polyvinylpyrrolidone or a plastic dispersion containing acrylate, styrene or PVAC.

Such a formulation of the filmable layer allows filming temperatures below or in the range of 100 ° C. These are conditions that can be easily set with cheap laminators. However, despite the low film-forming temperature, the formulation still allows a coating process for the substrate in which there is no premature filming of the coating when the application of the filmable layer dries, and moreover the substrate does not have to be stored under special conditions such as under cooling before printing. Furthermore, the low filming temperature also has the advantage that the carrier material does not dry out to the same degree during filming as is the case at temperatures above 100 ° C. In this way, the substrates remain flat after filming and the risk of jams in the laminator is reduced. It is shown that, in particular when using the above, deep-melting organic pigments, the use of the pressure fixing layer results in a precise and waterproof printed image.

Another embodiment is characterized in that the pressure-fixing layer is cationic and the ink is absorbent, particularly preferably water-resistant. In this way, the ink is actively removed from the layer sucked down and, since inks are usually anionic in character, precipitated and fixed by the cationic portions of the pressure-fixing layer. The printed image appears both with a high resolution, and there is also an increase in water resistance through the use of an already waterproof pressure-fixing layer.

Another embodiment of the invention is characterized in that the pressure-fixing layer particularly preferably contains the following components:

40-80% by weight, particularly preferably 60-70% by weight, of inorganic pigments,

5-40% by weight, particularly preferably 15-25% by weight, of cationic polymers, and 1-20% by weight of binder, silica or aluminum oxide hydrates preferably being the inorganic pigment, and a vinylamine polymer being the cationic polymer, N- Vinylamine-formamide polymer, a combination or copolymers thereof and a polyacrylate or polyvinyl alcohol is preferably used as the binder. The use of inorganic pigments leads to the desired suction power of the pressure-fixing layer, and the use of a cationic resin allows the permanent, water-resistant precipitation and local fixing of anionic inks in the layer.

Further embodiments of the invention and the methods and uses according to the invention are described in the dependent claims.

WAYS OF CARRYING OUT THE INVENTION

FIG. 1 shows a section through the layered structure of the proposed substrate 13. A carrier material 12, which as a rule can be paper, but possibly also a pretreated or partially synthetic paper or a film, is here preferably on the entire surface with a pressure-fixing layer 11 coated. There is a filmable coating 10 over the pressure-fixing layer 11 and covering the substrate on the surface. Depending on the area of application, the substrate 13 can also consist of a carrier material 12 coated on both sides with the layers 11 and 10. It can then be printed and filmed on both sides.

In addition to filming in laminating presses, the substrate 13 should in particular be filmable with conventional, if possible in particular inexpensive laminators. For now Inexpensive laminators for the continuous process which are available usually have at least one pair of counter-rotating rollers, between which the laminate is guided Laminating paper or the film heated before penetration between the rollers. In particular, the cheap laminators usually only allow the setting of a single predetermined temperature, normally in the range from 120 ° C. to 130 ° C., since cooling or special materials for rollers and Housing are necessary The pressure between the rollers can usually not be changed, and the transport speed, if at all, can often only be set between a few discrete values. Conventional filmable and printable substrates according to the prior art can be used in such lam Filming of the inators usually only unsatisfactorily, since higher filming temperatures and / or higher pressure are necessary, and furthermore the papers tend to bulge after filming

If, in order to avoid the above disadvantages, pigments which have lower glass transition temperatures are simply used in filmable papers according to the prior art, it is found that the printed images appear poorly resolved, the abrasion and water resistance decrease, and that a flowing of the printing ink already occurs during printing. Admixing inorganic pigments into the filmable layer 10 can increase the printing quality, but the water resistance remains unsatisfactorily poor

Excessive lowering of the glass transition temperature of the organic pigments also leads to problems in the coating process in the production of the papers If at least 30 ° C is chosen, a sensible compromise must be found when choosing the pigments

The three-layer laminate shown in FIG. 1 now solves this problem area in that the ink is bound by a pressure-fixing layer 11 after at least partial penetration into the porous filmable layer 10 just be eliminated. The inks, or corresponding colors, which due to their physicochemical properties are able to penetrate into the filmable layer 10, are sucked down and bound locally on the fixing layer 11. The water resistance remains so high that there is no blurring of the ink. Other printing inks, such as those used in offset processes and which cannot penetrate into the filmable coating due to their physicochemical properties, can also be applied, but remain essentially on the surface of the filmable coating after the printing process.

The possible use of deep-melting organic pigments makes it possible to significantly lower the locally occurring lamination temperature, in particular in the range of 100 ° C., which not only allows the use of cheap laminators, but also means that the carrier material 12 does not during the lamination process dries out so much and bulging of the papers therefore occurs less.

With regard to the type of carrier material 12 and its basis weight, there are no special requirements. Normal cellulose or cotton papers or combinations thereof with typical basis weights in the range between 80 g / m ² and 300 g / m ² are suitable. For prints of photographic representations it is preferred to use papers with a higher basis weight in the upper part of the specified range. The structure is the same for applications in the security area, but papers with additional security elements (such as watermarks, chemical security agents or paint applications containing iridescent pigments) in the weight range of 70-150 g / m ² are preferably used here.

The pressure fixing layer 11 is advantageously already applied in a step integrated in the paper production process, for example using a film press. The layer 11 should be absorbent so that the ink is actively absorbed by the layer 11 during the printing process from the filmable coating 10 onto the pressure fixing layer 11. In addition, the layer 11 should fix the ink and bind it waterproof. Conventional inks are mostly anionic in nature, and fixing is most easily achieved with cationic substances to which the ink components are locally bound in a precipitation. In order to achieve this, there must be inorganic, absorbent constituents (eg silicas), a cationic binder (eg cationic polyvinylamines) and preferably a binder around the dried layer to anchor the paper better. Additional components such as plasticizers or substances to maintain lightfastness and / or UV resistance can optionally be added.

The following composition of the pressure fixing layer 11, formulated for application as an aqueous dispersion, has e.g. proven suitable:

50 g Aerosil K315 (15% dispersion, weight of the dispersion)

70 g water

26.5g Catiofast ^* PR 8106 (22% dispersion, weight of the dispersion)

6 g Plextol E220 (60% dispersion, weight of the dispersion)

10 g Syloid 244 (powder weight)

Aerosil K315 (Degussa AG, DE) is a brilliant, white, absorbent, highly dispersed pyrogenic silicon dioxide. It is in the form of a 15% aqueous dispersion of the silica powder. Catiofast ^* PR 8106 (BASF, Ludwigshafen, DE) is actually an AOX-free wet strength agent for the production of wet-strength paper qualities in the neutral range. It is a light to dark yellow aqueous, 22% solution of a polymer based on vinylamine and N-vinyl-formamide and acts as a cationic, water-soluble, high-molecular resin for fixing anionic inks. It also acts as a binder. Plextol E220 (Polymer Latex GmbH & Co KG, Dormagen, DE) is a 60% dispersion of a self-adhesive acrylic polymer and acts as a binder. Syloid 244 (WR Grace & Co, USA) is a powdered matting agent made of silica, it also reduces the viscosity of the dispersion for the coating.

All ingredients except Catiofast are premixed and homogenized after adding Catiofast in a ball mill. The grain size can be set to <120μm or smaller if required. The dispersion has a pH in the range of 7.5. The layer should be in the range of 6-10 g / m ² , in the above-mentioned formulation 8-8.5 g / m ² are ideally applied.

The filmable coating 10 should have a minimum film-forming temperature which, on the one hand, enables filming at the lowest possible temperatures, but nevertheless permits an efficient drying process, ie meaningful drying temperatures for drying the filmable coating 10. The following composition of the filmable layer 10 formulated for application as an aqueous dispersion has proven to be suitable, for example:

60 g Baystal S21C (50% dispersion, weight of the dispersion)

15 g Gohsenol GL-03 (10% solution, weight of the solution)

5 g Mowiol 28-99 (10% solution, weight of the solution)

4 g Litex PS 5020 (50% dispersion, weight of the dispersion)

4 g Plextol E 220 (60% dispersion, weight of the dispersion)

0.5 g Tinuvin 213

30 g water

Baystal (Polymer Latex GmbH & Co KG, Dormagen, DE) is a 50% colloidal dispersion made from a copolymer of butadiene, styrene and acrylic acid and a low proportion of emulsifier. The styrene content is approximately 78%. Baystal forms the major part of filmable organic polymer with a glass transition temperature in the range of 50 ° C-60 ° C. These are pigment beads, such as those formed in emulsion polymerization, with a size in the range of 0.5 - 1 μm. Gohsenol (Nippon Gohsei, Osaka, JP) and Mowiol (Clariant, Muttenz, CH) are aqueous solutions of polyvinyl alcohol, serve as binders and have a water-absorbing effect. When using the substrate in offset printing, it is advisable to increase the proportion of binder if necessary by 50%. In order to avoid possible microscopic cracking in the filmable layer 10, particularly long-chain polyvinyl alcohols can advantageously be used. Litex (Polymer Latex GmbH & Co KG, Dormagen, DE) is an aqueous anionic 50% dispersion of a carboxylated styrene-butadiene copolymer (copolymer of butadiene, styrene and acrylic acid), which is used as a binder for coating colors in the paper industry. Litex has a glass transition temperature of approx. -6 ° C and serves here as a film-forming aid and to increase the gloss. Plextol (Polymer Latex GmbH & Co KG, Dormagen, DE) also serves with a glass transition temperature in the range of -47 ° C. Plextol is a 60% dispersion of a self-adhesive acrylic polymer. Tinuvin (Ciba SC, Basel, CH) is an optional UV stabilizer. It supports, among other things, the light fastness of the colors fixed in the underlying pressure fixing layer 11. Optionally, plasticizers, inorganic pigments or other additives can also be added. If the above constituents of the filmable layer 11 are mixed, particles of a size in the range of 20 μm are formed and the dispersion has a pH in the range of 8. The coating formulation can be applied offline or inline by means of a doctor blade application, a screen engraving roller, an air brush or in a casting process onto the substrate material 12 pre-coated with the pressure-fixing layer 11. The layer thickness should be chosen with the above formulation in the range of 9-12 g / m ² . If you choose thicker layers, a higher temperature must usually be selected for filming; with a thinner coating, the protective function of the layer is reduced.

The finished non-filmed substrate can be printed using a classic printing process, but is particularly suitable for printing using an inkjet process. There, the ink penetrates into or through the porous filmable layer 10 and is sucked in by the pressure-fixing layer 11 and fixed locally on it due to the cationic character of the layer 11. Those types of printing inks which cannot penetrate into the filmable coating remain, as already mentioned above, essentially on the surface of the filmable coating after the printing process. After printing, the paper can be passed through a laminator at a local laminating temperature in the range of 100 ° C without further processing. If the temperature of the laminator cannot be adjusted, the local laminating temperature can be adjusted by the transport speed through the laminator. As mentioned, pressure is preferably used at the same time for filming in addition to heat. A pressure in the range between 0.5-5 bar in a static press or a corresponding line pressure in a continuous laminator has proven to be sufficient and cheap. It is also conceivable to carry out the filming at a low temperature but with a very high pressure, but in most cases the time period during which the pressure is applied must then be increased significantly.

Water resistance and smudge resistance, but above all high brilliance are typical properties of paper prints of photographic images. With the invention, starting from electronically stored images, "paper prints" of practically the same quality can be produced by anyone with a standard inkjet color printer and a simple laminator. Compared to photo paper, the coated substrate according to the invention is usually cheaper. Even the surface condition of the images in the sense of "matt" or "glossy" can be controlled and determined in the simplest manner by choosing the surface which is in contact with the image surface under pressure during filming. For example, it is sufficient to run a matt or glossy film through a continuous laminator together with the image or print to be filmed. Films with a roughness between 0.01 - 5 μm are suitable for "matt" surfaces and those with a roughness less than 0.01 μm for "glossy" surfaces. After filming, the film must of course be easily removable from the filmed surface. Polyester or polyamide films (such as GRILON 6, 10, 12) are therefore suitable. Siliconized papers are also possible covers for the lamination process, and it turns out that especially not too thick papers with thick siliconization contribute to a good and even filming. For example, it is advantageous to design a so-called carrier in which the substrate to be filmed can be inserted and the inner surface of which has the desired surface structure. The substrate is placed in the carrier for the lamination process, and after the lamination, the carrier is removed again from the filmed paper. Such a carrier can ideally be used several times.

On the other hand, it is also possible to coat the rollers of the laminator directly in a suitable manner. Teflon or ceramic materials are likely to be suitable for rolls of continuous filming devices with a view to good releasability. In order to enable two different surface structures in a laminator without having to convert the laminator, it is advantageous to design the two rollers with different roughness depths so that the paper is sent through the laminator with the filmable layer up or down, depending on the desired surface.

By embedding the ink in the plastic film that forms, subsequent changes to the printed image are barely possible without this being recognizable. The invention is therefore particularly suitable for use in the security field, for example for the production of ID cards, passports, certificates or the like. The security paper can first be printed in the form of a classic printing process, such as an offset process, and then individualized by the end user with simple inkjet printing and then filmed in a laminator. The offset printing ink remains essentially on the surface, but is also partially welded in during filming and fixed. It is also conceivable to combine the substrate with the use of conventional film pockets, in which the paper is embedded and laminated, for outdoor applications or similar applications in which extremely pronounced protection of the printed image is necessary.

Claims

PATENT CLAIMS

1. Printable substrate, characterized in that a carrier layer (12) has a pressure-fixing layer (11) on at least one side, and that a filmable coating (10) containing film-forming organic pigments and binders is arranged on the pressure-fixing layer (11).

2. Substrate according to claim 1, characterized in that the filmable coating (10) contains the following components:

1-30% by weight, particularly preferably 2-10% by weight, of binder

0-20% by weight, particularly preferably 7-15% by weight, of film-forming aids

- 0 - 5 wt% UV stabilizers

- 0 - 5% by weight of oxidation stabilizers where:

- As organic pigments with a particle size preferably in the range 0.1-10 μm, particularly preferably in the range 0.5 to 2 μm, preferably styrenes, butadienes, acrylates and their copolymers or combinations thereof with glass transition temperatures in the range between 40 ° C. and 90 ° C., but especially between 50 ° C-70 ° C,

- As film-forming aids styrenes, butadienes, acrylates and their copolymers or combinations thereof with glass transition temperatures below room temperature, but in particular between (-50 ° C) - (+ 20 ° C), and

- Starch, polyvinyl alcohol, polyvinyl pyrrolidone or a plastic dispersion containing acrylate, styrene or PVAC are preferably used as binders.

3. Substrate according to one of claims 1 or 2, characterized in that the pressure-fixing layer (11) is cationic and absorbent, especially preferably water-resistant, and absorbent to a printing ink and / or ink.

4. Substrate according to one of claims 1 to 3, characterized in that the pressure-fixing layer (11) contains the following components:

5-40% by weight, particularly preferably 15-25% by weight, of cationic polymers, and

- 1-20 wt.%, Binder, where

- As inorganic pigment, preferably silicas or aluminum oxide hydrates,

- As a cationic polymer, preferably a vinylamine polymer, N-vinylamine-formamide polymer, a combination or copolymers thereof and

- A polyacrylate or polyvinyl alcohol is preferably used as the binder.

5. Substrate according to one of claims 1 to 4, characterized in that the filmable coating (10) with a basis weight of 9-12 g / m ² and the pressure-fixing layer (11) with a basis weight of 6-10 g / m ² , is particularly preferably applied of 8-9 g / m ² .

6. Substrate according to one of claims 1 to 5, characterized in that an optionally pretreated or partially synthetic paper or a film is used as the carrier layer (12).

7. A method for producing a substrate according to one of claims 1-6, characterized in that a paper substrate is pre-coated or impregnated on at least one side with a first mixture forming the pressure-fixing layer (11), and that the film-formable coating is applied via the pressure-fixing layer (11) (12) forming, filmable organic pigments and binder-containing second mixture is applied.

8. The method according to claim 7, characterized in that the first mixture and / or the second mixture are applied as aqueous dispersions.

9. The method according to any one of claims 7 or 8, characterized in that the first mixture is applied with a film press, preferably in a step integrated in the paper manufacturing process, that the second mixture with a doctor blade application, a screen engraving roller, an air brush or in one Casting method is applied, and that the subsequent drying of the filmable coating (10) is carried out at a surface temperature at which no filming of the filmable coating (10) occurs, particularly preferably at a maximum of 45 ° C.

10. Printed substrate, characterized in that it has at least one side a pressure fixing layer (11), in and / or on which ink is fixed, and that it has a filmed or sintered layer on the pressure fixing layer (11) which the pressure fixing layer ( 11) covers in a protective manner and in which, if appropriate, a further proportion of the printing ink and / or ink is embedded in filmed or sintered organic pigments and binders.

11. Printed substrate according to claim 10, characterized in that the pressure fixing layer (11) has the following composition apart from the printing ink and / or the ink and from paper fibers:

- 1-20 wt.%, Binder, where

- As inorganic pigment, preferably silicas or aluminum oxide hydrates,

- As a cationic polymer, preferably a vinylamine polymer, an N-vinylamine-formamide polymer, a combination or copolymers thereof and

a polyacrylate or polyvinyl alcohol is preferably used as the binder, and that the film-coated layer has the following composition apart from the printing ink and / or the ink and from paper fibers: 20-90% by weight, particularly preferably 70-90% by weight, of organic pigments,

1-30% by weight, particularly preferably 2-10% by weight, of binder

- 0- 20% by weight, particularly preferably 7-15% by weight, film-forming aid

- 0- 5% by weight UV stabilizers

- 0 - 5 wt .-% oxidation stabilizers where:

as organic pigments with a particle size preferably in the range from 0.1-10 μm, particularly preferably in the range from 0.5 to 2 μm, preferably styrenes, butadienes, acrylates and their copolymers or combinations thereof with glass transition temperatures in the range between 40 ° C. and 90 ° C., in particular however between 50 ° C-70 ° C,

12. A method for producing a printed substrate according to one of claims 10 or 11, characterized by the following steps:

Printing on a substrate according to one of claims 1 to 6,

- Filming the filmable coating (10) by application of heat, this at a temperature in the range between 70 ° C and 140 ° C, but in particular in the range of 80 ° C-100 ° C, optionally with simultaneous application of pressure, preferably between 0.5-5 bar.

13. The method according to claim 12, characterized in that the filming is carried out in a continuous process, particularly preferably in a laminator through heated rollers or through rollers combined with heating elements.

14. The method according to claim 13, characterized in that at least the roll facing the filmable coating has a coating Made of Teflon with a certain roughness depth which specifies the surface characteristics of the substrate surface in the filmed state.

15. The method according to any one of claims 12-14, characterized in that the filming is carried out immediately after the printing, in particular in an inkjet printer, still in the printer or in a filming unit connected to this.

16. Use of the method according to any one of claims 12-15 for producing a print with an abrasion-resistant and / or water-resistant surface.

17. Use of the method according to one of claims 12-16 for the production of an identification or security document, a certificate or the like.

18. Use of the method according to any one of claims 12-17 for the production of prints of photographs.