FR2694907A1 - Irreversible permanent information storage media process - uses microcapsules of colouring agent and active developer activated by piercing relevant capsules - Google Patents

Abstract

The process uses a medium (1) carrying a layer (2) consisting of at least one but possibly three colouring agents (3a,3b,3c) encapsulated in individual microcapsules distributed to form pixels on the surface of the medium. A second layer of microcapsules contains a developing re-agent (5) which fixes the colorant when they come into contact. Information such as an image is stored by piercing appropriate colorant capsules and reagent capsules in order to develop an appropriately coloured pixel. Alteration of the image is prevented by hardening the unused capsules by exposure to UV light or other radiation. USE/ADVANTAGE - For images on e.g. identity cards, bank cards. Permanent, irreversible storage of information.

Description

Support for recording information and recording method using such a support.

 The present invention relates to a medium for recording information.

 More specifically, it relates to media suitable for recording various information, for example images, texts or drawings, securely, without the possibility of subsequent falsification of the recorded information.

 It applies in particular to personalized memory cards containing not only the name of the card holder, but also a photograph of it.

 Since 1990, there has been a very significant development of memory cards in all sectors of economic and social life, for example for payment, security and information management. We have also tried to personalize these cards by incorporating a photograph of the user.

So, we know from the document
FR-A-2 626 392, a personalized chip card comprising an ABS support (acrylonitrile, butadiene and styrene copolymer) on which the chip was coUlated, and a housing for the placement of a photo of the card holder, the whole being covered with a layer of polyester about 26 μm thick. This solution which makes it possible to physically personalize the memory cards has given overall satisfaction, but it nevertheless has the disadvantage of not being able to prevent a possibility of falsification of the card in terms of photography, since the latter is not not printed directly in the card holder.

 Also, research has been carried out with a view to finding a technique for directly printing a photograph in the card holder.

 The object of the present invention is precisely a medium for recording information which enables a photograph to be recorded directly on the medium and to avoid any possibility of subsequent falsification of the recorded information.

According to the invention, the medium for recording information is characterized in that it comprises a substrate provided with a coating comprising
- at least one precolor agent distributed
on the substrate so as to form on
this one a network of separate areas
each containing a single precolo agent
rant, and
- a developer reagent capable of reacting
with the precolouring agent (s) for
develop a color, develop reagent
fear and / or the precolouring agent (s)
being included in microcapsules which can
be selectively open so
to release their content and allow
bringing the developer reagent into contact
with the precolouring agent (s) on
certain areas of the substrate.

The support of the invention is very interesting because it allows, on the one hand, to easily realize
The recording of information and, on the other hand, to avoid any subsequent falsification of the recorded information.

Indeed, thanks to the structure of the coating, one can easily carry out the recording of information by opening the microcapsules located at the places which correspond to the information to be recorded so as to put in contact the development reagent with the agent (s) precolorant (s) in the desired places and thus print on the support
The information to record.

The recording medium can then be neutralized by carrying out an appropriate treatment to prevent further opening of the microcaps.
Those who were not opened during the registration and thus avoid any possibility of subsequent modification of the recorded information.

 This treatment can consist of a hardening of the wall or the heart of the microcapsules which were not opened during the recording.

It can also consist of a general hardening of the structure by crosslinking of the coating; these crosslinks can be obtained, according to well known methods, using UV or ionizing radiation, or an electron beam etc.

 Generally, in the support of the invention, the coating comprises three different precolouring agents, capable of giving, for example, the three fundamental colors: green, red and blue.

 In this case, the precolouring agents are distributed in the coating so as to form a matrix comprising pixels each provided with three zones of different precolouring agents. Such a distribution corresponds, for example, to that of color display screens, in particular by liquid crystals.

 In the recording medium of the invention, the substrate can be made of various materials, for example paper, glass, or plastic such as copolymers of acrylonitrile, butadiene and styrene (ABS ), polyethylene, polyvinyl chloride and polyvinyl alcohol.

 In the coating, the precolouring agents used can be precolouring agents of the coupler type, for example azomethine type molecules, having a reactive methylene group capable of reacting with a chromogen to give rise to a color.

 In the case where three different precolouring agents are used, these can be constituted by Magenta, Cyan and Yellow couplers.

Magenta couplers can be chosen from cyano derivatives and pyrazolones. As examples of such couplers, mention may be made of 1-phenyl-3-methyl-5-pyrazolone, sulfonated phenylhydrazone, cyanacetythydrazones, indane-diones,
Benzoylamino pyrazolones, Phenylacetonitriles,
Oxindoles and Indazolones.

Cyan couplers can be chosen from phenolic compounds. As examples of such couplers, mention may be made of alpha and beta naphthols, hydroquinones, alpha-thionaphthol,
4-chlorophenylphenol and 1-hydroxy-2-naphthoyl-o-chloranilide.

 The yellow couplers can be chosen from Ketometylinic derivatives. As examples of such couplers, mention may be made of AcetylacetaniLides, 2,5-dichLoroaniLide acetylacetate, Benzoylacetanilides, Alpha and beta-benzoylacetami dobenzaldehydes, and M- and p-aminobenzoyLacetaniLides.

 The couplers used are chosen so that each coupler forms, by reaction with the developer reagent, a dye having a high transmission of the desired color, but the two colors generated by the other couplers must absorb weakly at this wavelength.

 The developer reagents capable of being used with these couplers can be a developer belonging to the classes of molecules commonly used in the photographic industry, for example a molecule derived from a paradiatkylaminoaniline.

This developer can be used either under
The form of diamine, either in the form of acid addition salts of this diamine, for example under
The form of hydrochloride or sesquisulfate.

As an example of such developers, mention may be made of N, N-diethyl-p-phenylenediamine,
The monochloride of N, N-di ethy Lp-phenyLe'nediamine, N, N (beta-hydroxyethyl) -ethyl-p-phenyLenediamine,
La N monohydrochloride, N-diethyL-2-methyLphenyLenediamine, sesqui su Lfate from 4-friend no-3-methyL-N, - N-ethyL- (2-hydroxyethyl) ani Line.

 According to the invention, it is also possible to use, as precoloring agents, leuco-dyes capable of being converted into coloring agents by reaction with an appropriate reagent such as an oxidizing agent.

 The Leucocolourants are also chosen so as to generate three colors, for example the three primary colors.

 In the carrier of the invention, the developing reagent and / or the precolouring agents are included in microcapsules which can be opened selectively so as to release their content.

This arrangement makes it possible to bring the reagent and the precolouring agents into contact at the time of
The opening of the capsules at the desired places to print an image on the support.

 According to a first embodiment of the support of the invention, microcapsules are used to include the developer reagent. In this case, the coating is advantageously formed of a first active layer comprising the precolouring agents and of a second layer of microcapsules filled with the developing reagent and placed in a binder.

The binder is advantageously a thermopLastic material having a glass transition temperature located in an alLant range of 50 to 600C, and having good adhesion properties with
The first active layer placed on the support.

 The binder must, moreover, be compatible with the wall of the mi crocapsu used.

 By way of example of a binder which can be used, mention may be made of synthetic latexes such as a styrene-butadiene emulsion, epoxy resins and derivatives of acrylic or methacrylic ester.

The binder can also comprise at least one additive chosen from - Wetting agents to facilitate dispersion
constituents, for example dioctyLsuLfosuccina
sodium, dodecybenzene sulfonate or
Sodium lauryLsuLfate, - Retaining agents or photosensitizers
absorbing Ultraviolet like Benzophenone and
Triazole, - Thickeners such as carboxymethyl
cellulose, gelatin, alginates, - defoamers such as diphosphate
lead, and - Coalescing agents to facilitate training
film at room temperature, for example
ethyl acetate gLycoL or hexylene glycol.

 Generally, the Binder represents 20 to 40% by weight of the first layer.

In this first embodiment of
The invention The microcapsules used can have diameters ranging from 10 to 20 μm; they are preferably thermolabile, waterproof, and optionally crosslinkable by ultraviolet radiation.

These microcapsules can be prepared by the chemical method known as "coacervation". The choice of the substance that constitutes the wall of the microcapsu
The is dictated by the physicochemical properties of the reagent to be encapsulated and by the mechanical properties that one wants to obtain.

As an example, the microcapsules can be made of natural or synthetic polymer, belonging to the category of the following water-soluble derivatives
- gelatin,
- gum arabic,
- Starch,
- polyvinyl alcohol and its derivatives, and
- Cellulosic derivatives such as carboxymethylcellulose, LlhydroxypropyLméthyL ceLlulose, Hydroxypropyl cellulose, hydroxyéthyL ceLLuLose and Cellulose acetates.

 Advantageously, when the opening of the microcapsules must be carried out by irradiation with mcyen of infrared radiation, there is also included in the wall of the microcapsules an infrared radiation absorber which will promote the opening of the microcapsules.

To sensitize the microcapsules with
The absorber can either be adsorbed on the wall, or included in the coacervate intended to form the wall, or produce mi c rocapsu Les with double walls by performing two successive encapsulation operations and arranging L absorber between the two walls.

The infrared absorber used is chosen so as to present a spectral absorption band at the emission wavelength of the infrared radiation source which will be used for
The opening of microcapsules. Otherwise,
The absorber must be compatible with the wall of the microcapsules, and its absorption in the visible must in no case harm the reproduction of the desired color, that is to say that the infrared absorber must present in the spectral zone. corresponding to the printed colors, a very low absorption coefficient.

 On the other hand, i L must have a high absorption coefficient at the wavelength of the infrared radiation used to open the microcapsules, for example a molecular absorption coefficient of at least 100 in the case of a source in Near infrared.

 The amount of infrared absorber used can range from 0 to 3% by weight relative to the total weight of the wall of a microcapsule.

 This infrared absorber can be an organic or inorganic compound.

Examples of inorganic compounds that may be mentioned include talc, anthracite, kaolinite,
Montmorillonite, Silicates such as zinc silicate, magnesium silicate and calcium silicate; Phosphates such as zinc phosphate, magnesium phosphate and calcium phosphate; Sulfates such as barium sulfate, calcium sulfate and strontium sulfate; and carbonates such as zinc carbonate, magnesium carbonate, calcium carbonate and
Barium carbonate.

By way of example of an organic absorber, mention may be made of triphenyl phosphates, furfuryl acetates, nickels dithienes functionalized or not such that
Bis- (4-NN-diethyLaminodithiobenzyl) -nickeL, bis (1-thio-2-phenolate) -nickel, naphthalocyanines such as alpha-magnesium phthalocyanine, cyanine halides such as 1,1-diethyL -6,6-dichLoro- 4,4-quinotricarbocyanine, and Le bis (1-thio-2-phenoLate) - nickeL-tetrabutylammonium.

In this first embodiment of
The invention, the first active layer can be constituted either by a matrix film of the precoloring agents, or by microcapsules filled with precoloring agent.

 When a matrix film is used, it can be produced with the precolouring agents of the coupler type or the leuco-coloring agents described above, by known printing techniques such as screen printing, in order to obtain a geometrically ordered and screened film comprising pixels. each with three zones of different colors.

 By way of example, the coupes Their can be incorporated into an optionally crosslinkable commercial ink, for example a glycerophtallic resin, collodion or an alkyd resin, or grafted onto a Latex or a simple or modified gelatin in correct proportions, then applied On the support by coating with an air knife, a scraper or any other method of deposition.

When the first active layer consists of microcapsules filled with precolouring agent,
The microcapsules can be prepared by coacervation, using the same techniques and the same substances as in the case of microcapsules filled with development reagent.

 They can also be single or double walled and include a red absorber.

 Usually. they are placed in a suitable binder by ordering them to form pixels, each comprising 3 microcapsules of different colorants.

 The binders used can be of the same type as those used for the second layer of development reagent microcapsules; they can also include additives such as those described above.

 In this first embodiment of the support of the invention, the first active layer is advantageously produced directly on the substrate and it is coated with the second active layer comprising the microcapsules.

 The selective opening of the microcapsules of the second layer and optionally the first layer can be obtained by sudden and localized heating of their wall, for example by the energy of an infrared beam, microwave or ultrasound.

This thermal effect results in the rupture of
The wall of the microcapsules concerned which release
The development agent in the binder of the second layer. The development agent migrates by diffusion into the first layer where it reacts with the precolouring agent from the underlying area to give a dye.

 The management of the colors formed is done by subtractive synthesis or CMYK system which fundamentally is based on the combination of the three dominant primary colors.

 The advantage of this mode of opening the microcapsules is that it makes it possible to select the neck pixel on the support, only by a thermal source which can be manipulated by a microcomputer and give a color with appreciable resolution.

 According to a second mode of reaction Li sati on of the support of the invention, the precoloring agents are included in microcapsules and the coating is formed by a first layer comprising the developing reagent and by a second layer of microcapsules each containing an agent Precolouring and arranged in a binder.

The microcapsules used in the second layer can also comprise an absorber of infrared radiation and they can be produced by the same technique as the microcapsules of the first embodiment of the support. The binder,
The substances and additives used to form
The microcapsules are chosen as above, according to the physicochemical properties of the precolourant to be encapsulated and the mechanical properties to be obtained. We can use the same substances, the same additives and the same binders as before.

 In this second embodiment of the support of the invention, the first layer comprising the developing reagent is preferably in contact with the substrate and coated with the second layer of microcapsules of precolourants. This first layer can consist of a homogeneous film of developer reagent.

 This homogeneous film constituting the first layer can be prepared as a printing ink by associating the developing reagent with substances adapted to limit the diffusion of the precolouring agent in the homogeneous reagent film when the microcapsules of the second are opened. layer.

According to a variant of this second embodiment, the first layer consists of microcapsules filled with developer reagent and arranged in a binder, and it is in contact with
The substrate.

 In this case, the same techniques and the same constituents as in the first embodiment can be used to prepare this layer of microcapsules.

 In the various embodiments of the invention, a crosslinking agent can be included in the coating to neutralize the system after recording the desired information.

This crosslinking agent can be in
The heart or the wall of the microcapsules or in the
Binder used with the microcapsules of the first layer and / or the second layer.

 The crosslinking agent used will be chosen according to the material to be crosslinked.

 According to an advantageous arrangement of the invention, the recording medium further comprises a protective film disposed above the coating comprising the precolours and the development reagent.

 This film can be made of polymer and have, for example, a thickness of 1 to 5 # m.

 The polymer used must have a very low absorption coefficient for the radiation used to open the microcapsules, as well as for the ultraviolet radiation possibly used to make the recorded information tamper-proof.

It must also have good transparency in the visible, good adhesion to the coating and good resistance to water, chemical agents and abrasion.

Other characteristics and advantages of the invention will appear better on reading
The following description of exemplary embodiments given of course by way of illustration and not limitation with reference to the appended drawing in which:
FIG. 1 schematically represents in vertical section a recording medium according to the first embodiment of the invention,
Figure 2 shows in vertical section
The support of Figure I after recording information, and
- Figure 3 shows in vertical section a recording medium according to the first embodiment of the invention using a matrix film of precolouring agents.

 In FIG. 1, it can be seen that the recording medium of the invention comprises a substrate (1) provided with a coating (2) comprising precolouring agents (3a, 3b, 3c) and a developer reagent (5).

According to the first embodiment of the invention, the coating (2) comprises a first active layer (4) comprising the precolouring agents (3a, 3b, 3c) and a second layer (6) of microcapsules
(51, 52 ... 5n) filled with the developer reagent.

The precolourants (3a, 3b, 3c) are organized in
the first layer (4) so as to form pixels p each comprising three zones of precolourants (3a, 3b and 3c) of different colors. In this embodiment, the precolourants are included in microcapsules. The microcolor capsules of precolorants (3a, 3b and 3c) and The microcapsules (51,52. 5n) of the developer reagent are placed in a binder
(7) which contains a suitable crosslinking agent.

In Figure 2, there is shown the recording medium of Figure 1 after it has been used for recording information. To make this recording, we selectively opened
The microcapsules of the support located in the places corresponding to the information to be recorded.

 Thus, it can be seen in FIG. 2 that the first developer reagent microcapsule (51) and the first precolorant microcapsule (3a) were opened by the action of a thermal or mechanical energy source S, constituted for example by a source of infrared radiation.

 In the case of a thermal source, the heating caused the rupture of the wall of the microcapsules and the release of their contents. As a result, the developer reagent of the microcapsule (51) has been released and has diffused in the first underlying active layer (4) where it has been able to react with the precolourant released from the microcapsule (3a) to form a pixel of color.

After the recording operation, the assembly is subjected to ultraviolet radiation to crosslink the two layers of binder and thus prevent the reagent microcapsules (52 to 5n) and the underlying precolorant microcapsules from being able to
release their content and modify the information previously recorded.

In FIG. 3, another recording medium has been represented in accordance with the first embodiment of the invention, and the same references have been used as in FIG. 1 to designate
The components of this recording medium.

This differs only from the support of FIG. 1, by the fact that the first active layer (4) is constituted by a matrix film comprising the three precolourants (3a, 3b, 3c) arranged on the substrate (1), without being encapsulated, in the form of a geometrically ordered and screened film to form pixels as in the case of FIG. 1. The second layer (6) comprising the developer reagent is identical to the second layer of
Figure 1.

 As in the case of FIG. 1, the recording is carried out by subjecting the desired microcapsules to the action of a heat source to deteriorate their walls and release their content so that it can react with the precolorant. (3a, 3b or 3c) located immediately below.

As before, the system can then be neutralized by irradiation using radiation (ultraviolet, ionizing, etc.) to crosslink
The microcapsules or the binder (7) and prevent
The subsequent opening of the microcapsules (5) which were not opened during the information recording operation.

The sources of thermal or mechanical energy capable of being used to damage the wall of the microcapsules, can be constituted by a microwave emitter, an ultrasonic generator or a laser, for example a gas laser of the type
C02 or CO which has several usable wavelengths, a YAG laser (1.0241ut) or a laser diode (solid state semiconductor of modulable in intensity).

 It is also possible to use any other source of non-coherent infrared light, with or without filter, which can give, with appropriate optics, a sufficiently convergent beam. In order to obtain an appropriate thermal activation, the useful wavelengths of the beam are in the near infrared and the infrared (750nm at 20pu).

 For the support neutralization operation, a light source may be used chosen so as to provide maximum emission in the ultraviolet. Xenon, mercury or xenon-mercury lamps or tubes, continuous or pulsed, can be used. A source of ionizing radiation or an electron beam can be used under certain conditions.

In the case of the source used for
When the microcapsules are opened, the beam can be controlled spatially by acousto-optical or electro-optical deflectors, or even by vibrating mirrors, to reach the designated pixel. These devices can optionally be combined with polygonal rotating mirrors. The beam is moreover modulated in amplitude by any suitable device so as to deliver the thermal power only at the desired time and at the desired location.

 The process of the invention is therefore very advantageous since the recording is carried out by a dry thermal process, and the wavelength of the energy sources used does not have to be adapted to the precolorants used.

 Furthermore, this process can be implemented with conventional devices, and known techniques, such as those used in electronics for making printed circuits, can be used for the manufacture of the recording medium.

 By way of example, an exemplary embodiment of the recording medium in FIG. 1 is given below.

 For this manufacture, microcapsules containing the developer reagent or the precolouring agents are first prepared.

 a) Preparation of the developer microcapsules.

 39 of diethylparaphenylenediamine are dissolved in toluene, the whole being emulsified with 1009 of an aqueous solution of cellulose ester containing 2 g of cellulose acetate and 0.89 of disodium hydrogen phosphate to hydrate the cellulose ester .

 The solution is dispersed and the temperature is raised to 600C for 20 min to reduce the viscosity of the mixture. 20 ml of an aqueous solution of sodium sulphate are then added dropwise to the solution, with stirring at 900 revolutions / min.

The temperature of the reaction mixture is then lowered to 50C to produce phase separation and
Particle formation in situ. We harden then
The microcapsules by adding a 2% acetic acid solution to reach a pH of 4.5.

 The microcapsules formed are then extracted by centrifugation, washed with a 1% aqueous sodium sulfate solution and filtered several times. The microcapsules are then dried in an oven at 300C for 24 hours, then they are sieved to retain only the microcapsules having a size of 10 to 15pu.

 The retained microcapsules are then subjected to a second coating to form double-walled capsules containing, between the two walls, nickel dithiene playing the role of infrared absorber.

 To carry out this second coating, 29 of the microcapsules obtained previously and 0.29 of nickel-dithiene are dispersed in an aqueous solution of cellulose ester at 2%, then the procedure is carried out in the same way as above to obtain microcapsules, but performs stirring at 500/700 revolutions / minute during the addition of the aqueous sodium sulfate solution.

Double-walled microcapsules are thus filled filled with a developer reagent consisting of diethylparaphenylenediamine and comprising between
The two walls an infrared radiation absorber consisting of nickel-dithiene.

 b) Preparation of microcapsutes of precolourants.

 For this preparation, the same procedure is followed as above except that the diethylparaphenylene diamine is replaced by a precolouring agent.

 These microcapsules are then used to form a coating on a substrate consisting of an ABS sheet having a thickness of 1 mm.

 c) Preparation of the coating.

 First of all, the first active layer is deposited on the substrate, using masks to successively deposit the microcapsules of Magenta precolorant, Cyan precolorant and yellow precolorant and obtain the organized network of precolourant zones.

 For this deposition, the microcapsules are incorporated into a coating composition composed of PS (polystyrene) / DVB (divinylbenzene) / benzophenone.

 After completion of the first active layer, the second layer is deposited on the first layer using the same coating composition with the microcapsules containing the developer agent which is applied to the support by coating with a scraper. The assembly is then protected by placing a polyester film on the second layer.

To carry out the recording of information on the support thus produced, one can use a source of infrared radiation emitted by a laser source (solid or gas), and one can then neutralize
The whole by irradiation by means of ultraviolet radiation emitted by a mercury vapor lamp.

 Such a medium can be used in particular as a memory card comprising a color photograph of the holder of the card.

Claims (17)

 1. Support for recording information, characterized in that it comprises a substrate (1) provided with a coating comprising - at least one precolouring agent (3a, 3b, 3c) distributed  on the substrate so as to form thereon  a network of distinct zones each containing  a single precolouring agent, and - a developer reagent (5) capable of reacting with  the precolouring agent (s) to develop a  color, the developer reagent and / or the precolouring agent (s) being included in microcapsules (51, 52 5n> which can be opened selectively so as to release their content and allow the reagent to be brought into contact developer with the precolouring agent (s) on certain areas of the substrate.  2. Support according to claim 1, characterized in that the coating comprises three different precoloring agents.  3. Support according to any one of claims 1 and 2, characterized in that the precolouring agents are couplers and in that the developer reagent is a developer capable of reacting with these couplers.  4. Support according to any one of claims 1 and 2, characterized in that the precoloring agents are leuco-dyes and in that the developer reagent capable of reacting with the precoloring agents is an oxidizing agent.  5. Support according to any one of claims 1 to 4, characterized in that the developer reagent is included in microcapsules and in that the coating is formed of a first active layer comprising the precolouring agents and of a second layer microcapsules filled with the developer reagent and placed in a binder.  6. Support according to claim 5, characterized in that the first active layer consists of a matrix film of precolouring agents.  7. Support according to claim 5, characterized in that the first active layer comprises microcapsules each containing a precolouring agent, arranged in a binder.  8. Support according to any one of Claims f to 4, characterized in that the precolouring agents are included in microcapsules and in that the coating is formed from a first layer comprising the developer reagent and from a second layer of microcapsules containing each a precolouring agent and arranged in a binder.  9. Support according to claim 8, characterized in that the precolouring agents are couplers.  10. Support according to any one of claims 8 and 9, characterized in that the first layer consists of a homogeneous film of developer reagent.  11. Support according to any one of claims 1 to 10, characterized in that the wall of the microcapsules comprises an absorber of infrared radiation.  12. Support according to any one of claims 5 and 7 to 9, characterized in that a crosslinking agent is introduced into the core or the wall of the microcapsules or into the binder.  13. Support according to any one of claims 1 to 11, characterized in that it comprises  moreover a protective polymer film placed at the  above the coating.  14. Method for recording information  on a support, characterized in that it consists  to submit a recording medium according to One  any of claims 1 to 13, to treatment  allowing to selectively open Micro-capsules  of the support located in the corresponding places  to the information to be recorded, so as to put  in contact with the areas of precolouring agent with the  developer responsive where needed and to train  thus on the support a corresponding colored image  to the information to be recorded.  15. The method of claim 14,  characterized in that the support is then submitted  provided with the colored image to a hardening treatment -to prevent further release of the contents  microcapsules which have not been opened during  of the formation of the Colorful image and avoid any  possibility of subsequent modification of information  recorded on the medium.  16. The method of claim 14,  characterized in that the opening treatment of  micro-capsules consists in submitting the micro-capsules  to the action of microwaves, ultrasonic waves or  of an infrared beam.  17. The method of claim 15,  characterized in that the hardening treatment  consists in irradiating the support by means of radiation  ultraviolet or ionizing, or a beam of electrons  to crosslink the coating.