EP1279169A1

EP1279169A1 - Utilization of beam crosslinkable polymer compositions as data recording medium

Info

Publication number: EP1279169A1
Application number: EP01936325A
Authority: EP
Inventors: Wolfgang Schrof; Harald RÖCKEL; Rüdiger FÜSSL; Karl-Heinz Schumacher; Ralf Fink
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2000-05-04
Filing date: 2001-05-04
Publication date: 2003-01-29
Also published as: JP2003531760A; US6964837B2; WO2001084544A1; US20030175506A1

Abstract

The invention relates to the utilization of at least one beam crosslinkable, preferably UV-crosslinkable, polymer composition as data recording medium, especially as so-called smart coatings based on said polymer compositions, which in another embodiment contain at least one fluorescence chromophore. The invention also relates to a composite containing at least one carrier and one layer containing a beam crosslinkable polymer composition containing at least one fluorescence chromophore and also, preferably, an additional UV-absorbing layer.

Description

Use of radiation-crosslinkable polymer compositions as a data recording medium

The present invention relates to the use of at least one radiation-crosslinkable, preferably UN-crosslinkable, polymer composition as a data recording medium, in particular as so-called smart coatings based on such polymer compositions.

In addition, the present invention also relates to the use of at least one radiation-crosslinkable polymer composition containing at least one fluorescence chromophore as the data recording medium, and also a composite. The. Composite has a support and a layer containing at least one radiation-crosslinkable polymer composition with at least one fluorescence chromophore. The composite preferably has an additional UV-absorbing layer.

Polymers crosslinkable by UV light and their use, for example, as an adhesive, e.g. as a hot melt adhesive or as a coating agent such as e.g. as lacquer, are known. For this purpose, we refer, for example, to DE-A 24 11 169, EP-A 0 246 848, DE-A 40 37 079 or DE-A 3 844 444 and DE-A 199 35 624, DE-A 100 08 295 and DE-A 199 46 898 (adhesives) and DE-A 198 36 788, EP-A 0 947 565, EP-A 0 921 168 and DE 198 26 716 (coating compositions, lacquers) and the prior art cited therein.

Such coatings have not previously been used to store data or as a data recording medium. Accordingly, the present The present invention makes use of a further property of such compositions, namely that it is possible to impart information to this by locally irradiating such UV-crosslinkable polymer compositions, which information can subsequently be read out again using suitable reading devices.

A potential application of the polymer compositions according to the present invention are the so-called smart coatings. This means coatings made from the polymer composition used according to the invention which, in addition to their typical, e.g. have readable information (data) to promote adhesion or surface protection properties. This information can be digital information (e.g. point or bar codes) or holographic in nature.

Smart labels based on Tesafilm, a polymer film based on polypropylene, are a well-known application in this technical field of information storage in polymers. In this application of tesafilm, referred to as “Tesa-ROM”, to write on the tesafilm, it is heated at individual points / points by a laser and the stretched polypropylene film is relaxed locally. The optical properties of the tesafilm thus begin to change from a certain temperature The information remains transparent, but reflects less light than before. When reading the information stored in this way, the heat, ie the energy density of the laser light, is no longer used, but the brightness of the emitted light. Since the "described" scotch tape reflects less light than the "unwritten" one, the laser light reflected on the scotch tape can be read and evaluated by means of a light-sensitive cell. Such a scotch tape can then be glued to a substrate and thus used as a "smart label" analogous to a bar Codes that refer to the respective substrate contain the necessary information, e.g. to which customers the item with the smart label should be sent. Also suitable According to its manufacturers, "Tesa-ROM" is also generally a data storage medium analogous to a CD.

Smart coatings or data recording media based on the free-radically or ionically polymerized, radiation-crosslinkable polymer compositions in question are not yet known.

In addition, the "Tesa-ROM" concept based on Tesafilm has the disadvantage that these films are not thermally stable and the stored information is lost, in particular at higher ambient temperatures.

Accordingly, the object of the present invention was to provide new data recording media which should be universally applicable and should be easy to handle or process and which preferably ensure easy readability of the stored information.

The present invention thus relates to the use of at least one radiation-crosslinkable polymer composition as a data recording medium.

In principle, all radiation-crosslinkable, preferably UV-crosslinkable, free-radically or ionically polymerized polymers can be used as polymer compositions. In particular, the polymer composition used according to the invention is an adhesive or lacquer composition, in each case in the form of a melt, as a solution or as an aqueous dispersion. In this regard, we refer to the prior art cited at the beginning with regard to adhesives and coating compositions or lacquers, the contents of which, with respect to the polymer compositions described there, are included in full in the context of the present application by reference. The polymer composition preferably further comprises at least one radiation-activatable compound. This compound is preferably an ethylenically unsaturated radiation-activatable compound, in particular a compound from the group of photoinitiators. By irradiation with high-energy light, in particular UV light, the radiation-activatable compound brings about crosslinking of the polymer, preferably by means of a chemical graft reaction of the photoinitiator with a spatially adjacent polymer chain. In particular, the crosslinking can be carried out by inserting a carbonyl group of the photoinitiator into an adjacent CH bond to form a -CC-OH group.

The polymer composition preferably contains 0.0001 to 1 mol, particularly preferably 0.0002 to 0.5 mol, very particularly preferably 0.0003 to 0.05 mol of the radiation-activatable compound or the radiation-activatable molecule group, per 100 g Polymer.

The radiation-activatable connection is e.g. Acetophenone, benzophenone, benzoin ether, benzyl dialkyl ketols or their derivatives.

The radiation-activatable compound or the radiation-activatable molecule group is preferably bound to the polymer.

It is particularly preferably a radiation-activatable group of molecules which is incorporated into the polymer chain by radical copolymerization. This is preferably an acrylic or methacrylic group.

Suitable copolymerizable compounds which can be activated by radiation are photoinitiators such as, for example, acetophenone, benzophenone, and also acetophenone or benzophenone derivatives which contain at least one, preferably one ethylenically unsaturated, group. The ethylenically unsaturated group is preferably an acrylic or methacrylic group. Accordingly, the invention also relates to the use of at least one radiation-crosslinkable polymer composition as a data recording medium, acetophenone, benzophenone, a derivative of acetophenone or bezophenone or a mixture of two or more thereof being used as the radiation-activatable compound and preferably being copolymer-bound.

The ethylenically unsaturated group can be bonded directly to the phenyl ring of the acetophenone or benzophenone derivative. Generally there is a spacer group between the phenyl ring and the ethylenically unsaturated group.

The spacer group can e.g. contain up to 100 carbon atoms.

Suitable acetophenone or benzophenone derivatives are e.g. in EP-A 346 734, EP-A 377 199 (1st claim), DE-A 4 037 079 (1st address) and DE-A 3 844 444 (1st claim) and are also referred to by this reference in the present application disclosed. Preferred acetophenone and benzophenone derivatives are those of the formula

wherein R ^{1 stands} for an organic radical with up to 30 C atoms, R ² for a H atom or a methyl group and R ³ for an optionally substituted phenyl group or a C ₁ -C ₄ alkyl group. R ¹ particularly preferably represents an alkylene group, in particular a C ₂ - Cg alkylene group.

R ³ particularly preferably represents a methyl group or a phenyl group.

In a further embodiment of the present invention, so-called “dual cure” systems can be used, ie combinations of polymer and radiation-activatable compounds that comprise more than one radiation-activatable compound. For example, a combination of a thermally crosslinkable and a UV-crosslinkable compound is conceivable or a combination of a compound that can be crosslinked in the visible range of light and a UV-crosslinkable compound. Thus, with one of the two compounds the polymer can be crosslinked in a "classic" manner and with the other compound it can be crosslinked in a spatially resolved manner and thus the polymer composition with a To provide information.

The polymer is preferably composed of free-radically or ionically polymerizable compounds (monomers), preferably those with at least one ethylenically unsaturated group.

In a further embodiment, the invention thus relates to the use of at least one radiation-crosslinkable polymer composition as a data recording medium, the polymer composition comprising at least one radically or ionically polymerized, radiation-crosslinkable polymer which was formed from monomers having at least one ethylenically unsaturated group.

The polymer preferably consists of at least 40% by weight, particularly preferably at least 50% by weight, very particularly preferably at least 80% by weight, of so-called main monomers, which are preferably monomers with at least one ethylenically unsaturated group. The invention therefore also relates to the use of at least one radiation-crosslinkable polymer composition as a data recording medium, the free-radically or ionically polymerized, radiation-crosslinkable polymer comprising at least 50% by weight of units which, starting from at least one monomer with at least one ethylenically unsaturated group were formed.

The main monomers are selected from the group of α, β-monoethylenically unsaturated C ₃ -C ₆ carboxylic acids, C ₂₀ -C alk 5d (meth) acrylates, butadiene, vinyl esters and allyl esters of C ₁ -C ₄ -alkyl carboxylic acids, vinyl aromatics with up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 carbon atoms, aliphatic hydrocarbons with 2 to 8 carbon atoms and 1 or 2 double bonds or mixtures of these monomers.

Examples include (Meth) acrylate with a Cι-Cιo-alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.

Mixtures of the (meth) acrylic acid alkyl esters are also particularly suitable.

Vinyl esters of carboxylic acids with 1 to 20 C atoms are e.g. Vinyl laurate, vinyl acetate, vinyl propionate, vinyl versatic acid and vinyl acetate.

Suitable vinyl aromatic compounds are vinyl toluene, alpha- and p-methylstyrene, alpha-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene. Examples of nitriles are acrylonitrile and methacrymitrile.

The vinyl halides are chlorine, fluorine or bromine-substituted ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride. Examples of vinyl ethers are vinyl methyl ether or vinyl isobutyl ether. Vinyl ethers or alcohols containing 1 to 4 carbon atoms are preferred.

Butadiene, isoprene and chloroprene may be mentioned as hydrocarbons with 2 to 8 carbon atoms and two olefinic double bonds.

Preferred main monomers are the C 1 to C ₁₀ alkyl acrylates and methacrylates, in particular C 1 -C ₈ alkyl acrylates and methacrylates, the acrylates being particularly preferred in each case.

Methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, n-hexyl (meth) acrylate, octyl (meth) acrylate and 2-ethylhexyl (meth) acrylate and mixtures of these monomers are very particularly preferred.

In addition to the main monomers, the polymer may contain other monomers, e.g. Monomers with carboxylic acid, sulfonic acid or phosphonic acid groups. Carboxylic acid groups are preferred. For example, Acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid.

Other monomers are e.g. also monomers containing hydroxyl groups, in particular C 1 -C hyroxyalkyl (meth) acrylates, (meth) acrylamide.

Other monomers include its phenyloxyethyl glycol mono- (meth) acrylate, glydidyl acrylate, glycidyl methacrylate, amino (meth) acrylates such as 2-aminoethyl (meth) acrylate.

Monomers which carry other functional groups in addition to the double bond, for example isocyanate, amino, hydroxyl, amide or glycidyl, can, for example, improve the adhesion to substrates. In particular, a polymer is used in the polymer composition which consists of 50 to 99.95% by weight of monomers with at least one ethylenically unsaturated group and 0.05 to 50% by weight of a radiation-activatable compound, preferably 50 to 99.95% by weight .-% -C ₂ o-alkyl (meth) acrylate and 0.05 to 50 wt .-% of a benzophenone or acetophenone derivative is formed.

Accordingly, in a further embodiment, the invention relates to the use of at least one polymer composition as a data recording medium, the polymer comprising 50 to 99.95% by weight of monomers with at least one ethylenically unsaturated group and 0.05 to 50% by weight. -% of a radiation-activatable compound, preferably copolymer-bound, was formed.

In a further embodiment, the invention relates to the use of at least one polymer composition containing at least one fluorescence chromophore as the data recording medium.

According to the invention, the polymer composition can contain 0.05 to 5% by weight fluorescent chromophore, based on the total polymer composition, preferably 0.1 to 3% by weight, in particular 0.1 to 1% by weight.

The fluorescent chromophore is e.g. to coumarin, (bis) stilbene, perylene, phenanthridine, fluorene, a derivative of coumarin, (bis) stilbene, perylene, phenanthridine or fluorene. Mixtures of two or more fluorescent chromophores can also be used within the scope of the present invention.

In a preferred embodiment of the present invention, the fluorescence chromophore is bound to the polymer. In the context of the present invention, the incorporation into the polymer can take place, for example, by reaction of a reactive group of the fluorescence chromophore, for example an ethylenically unsaturated group. The ethylenically unsaturated group can be bonded directly to the fluorescent part of the molecule or can be part of the fluorescent part of the molecule. However, it is also possible for a spacer group (spacer) to be located between the fluorescent part of the molecule and the ethylenically unsaturated group. The spacer group can contain up to 100 carbon atoms, for example, the spacer group is preferably an alkyl group.

By using a mixed or polymerized fluorescence chromophore, it participates in the radiation-induced, in particular UV-induced, crosslinking reaction. This effectively suppresses fluorescence at the exposed areas. In the context of the present invention, a synergistic effect preferably occurs, that is to say a targeted exposure of the photoinitiator, and thus the absorption of the radiation by the photoinitiator, leads to an efficient quenching of the fluorescence chromophore. A macroscopically different degree of cross-linking and thus different levels of fluorescence in such a polymer layer can be generated, for example, by means of mask technology.

In particular, a polymer is used in the polymer composition which consists of 50 to 99.90% by weight of monomers with at least one ethylenically unsaturated group, 0.05 to 45% by weight of a radiation-activatable compound, preferably copolymer-bound, and 0 , 05 to 5 wt .-% of a fluorescent chromophore, preferably copolymer-bound, preferably 50 to 99.90 wt .-% C ₁ -C ₂ o-alkyl (meth) acrylate, 0.05 to 45 wt .-% of a benzophenone - Or aceto-phenone derivative and 0.05 to 5 wt .-% of a bisstilbene derivative is formed, the total amount of monomer, radiation-activatable compound and fluorescent chromophore is 100%.

The polymer composition preferably has a K value of> 10, preferably 30 to 100 and in particular 30 to 80, in each case measured in tetrahydrofuran (1% solution, 21 ° C.). The Fikentscher K value is a measure of the molecular weight and viscosity of the polymer.

The glass transition temperature of the polymer is generally below 200 ° C, preferably from -60 ° C to <200 ° C, more preferably from -50 to +150 ° C, particularly preferably from -45 to +120 ° C and very particularly preferably at -40 to +100 ° C.

The glass transition temperature of the polymer can be determined by conventional methods such as differential thermal analysis or differential scanning calorimetry (see e.g. ASTM 3418/82, so-called "midpoint temperature").

The polymers used according to the invention can be prepared by copolymerization of the monomeric components using the customary polymerization initiators and, if appropriate, regulators, polymerization being carried out at the usual temperatures in bulk, in emulsion, for example in water or liquid hydrocarbons, or in solution. The copolymers are preferably obtained by polymerizing the monomers in solvents, in particular in solvents having a boiling range from 50 to 150 ° C., preferably from 60 to 120 ° C., using the customary amounts of polymerization simiators, which are generally from 0.01 to 10, in particular 0.1 to 4 wt .-%, based on the total weight of the monomers. Particularly suitable solvents are alcohols, such as methanol, ethanol, n- and iso-propanol, n- and iso-butanol, preferably isopropanol and / or isobutanol, and hydrocarbons such as toluene and in particular gasolines with a boiling range from 60 to 120 ° C. Furthermore, ketones, such as acetone, methyl ketone, methyl isobutyl ketone and esters, for example ethyl acetate, and mixtures containing isopropanol and or isobutanol in amounts of 5 to 95, in particular 10 to 80, preferably 25 to 60% by weight, based on the mixed solution used, are preferred. Possible polymerization initiators in solution polymerization are, for example, azo compounds, ketone peroxides and alkyl peroxides.

After the polymerization in solution, the solvents can, if appropriate, be removed under reduced pressure, operating at elevated temperatures, for example in the range from 100 to 150 ° C. The polymers can then be in a solvent-free state, i.e. used as melts. In some cases, it is also advantageous to process the new UV-crosslinkable polymers by bulk polymerization, i.e. to produce without the use of a solvent, with batch or continuously, z. B. according to the information of US 4 042768, can work.

The polymers used in the composition used according to the invention are preferably solvent-free. A residual solvent content, e.g. organic solvents and / or water, but can be less than 10 parts by weight, in particular less than 5 parts by weight, particularly preferably less than 2 parts by weight, very particularly preferably less than 1 part by weight of solvent, based on 100 parts by weight. Parts polymer.

With regard to further details for the polymerization of the polymers in question, reference is made to DE 19935624.6 (emulsion polymerization) and DE 10008295.5 and DE 19946898.2, the respective prior art cited therein and general textbooks for radical polymerizations, the contents of which are fully in the context the present application is incorporated by reference.

With regard to the ionic polymerization that can also be used depending on the monomers, reference is also made to the relevant textbooks. The polymer composition can be present as a melt, as a solution in an organic solvent or as an aqueous dispersion and can be used in this form.

Preferably the polymer compositions are melted, i.e. essentially solvent-free (solvent content preferably less than 2% by weight, based on the polymer).

The polymer composition can be, preferably from the melt, by conventional methods, e.g. Brushing, rolling, pouring, knife coating and extrusion can be applied to carriers. In the case of solution or aqueous dispersion, the solvent or water is removed, generally by drying.

To increase the flowability of the polymer composition, the temperature thereof when applied as a melt may be 10 to 150 ° C., preferably 50 to 150, particularly preferably 100 to 150 ° C.

Preferred layer thicknesses are e.g. 2 to 200 μm, particularly preferably 5 to 150 μm, very particularly preferably 10 to 100 μm.

Possible carriers are e.g. Paper or plastic labels, e.g. Polyester, polyolefins or PVC, as well as adhesive tapes or foils made of the above plastics.

To be mentioned in particular: polymer films, in particular made of polyethylene, oriented polypropylene, polyamide, polyethylene terephthalate, cellulose acetate, cellophane, with metal, for example aluminum, coated (vapor-coated) polymer film or also paper, cardboard or metal foils, in particular those made of aluminum. The films mentioned can also be printed with drack colors, for example. In addition, metallic surfaces, in particular aluminum, iron, steel or chrome, can also be coated. The polymer compositions are then irradiated with high-energy radiation, preferably UV light.

In general, the coated carriers are placed on a conveyor belt and the conveyor belt is placed on a directed, high-energy radiation source, e.g. a laser, passed by. If necessary, the polymer composition is first crosslinked thermally or by means of high-energy, non-site-specific radiated energy. In order to provide information, local networking is then carried out using a directed radiation source, e.g. a UV laser. With this procedure, either the “dual cure” systems already described above with various types of radiation-activatable compounds can advantageously be used. The procedure can be as follows: firstly, irradiation is carried out in the visible wavelength range (non-directional) and then directing with UV Irradiated with light, or vice versa;

First, it is crosslinked thermally (non-directional) and then irradiated with UV light.

A further variant using a type of radiation-activatable compounds is first to use a radiation dose that is too low to activate all potential groups that cause crosslinking, to crosslink non-directionally (pre-crosslinking) and then to irradiate again in order to introduce information ,

The degree of crosslinking or the information input into the polymer composition depends on the duration and intensity (dose) of the irradiation.

The radiation energy (UV dose) is preferably a total of 100 to 2000 mJ / cm ^{2 of} irradiated area. Of course, the polymer composition can also be located as an adhesion-promoting layer between two supports, preferably between two supports of the type mentioned above, and then subjected to irradiation with UV light, in particular laser light, in order to introduce information. The polymer compositions in question can generally be activated in a wavelength range from 200 to 2000 nm, preferably 200 to 500 nm and in particular 230 to 400 nm. The depth of inscription can be chosen freely in a wide range and is typically 5 to 100 micrometers. The resolution of such radiation is generally better than 10 micrometers.

By means of laser radiation, for example by means of two interfering UV lasers, a permanent, spatially resolved “crosslinking pattern” is written into the layered polymer composition and can then be read out by appropriate devices. This is preferably done spectroscopically, more preferably by means of IR (absorption spectrum) ) or Raman spectroscopy (reflection spectrum), preferably confocal Raman spectroscopy or by determining the difference in refractive index between areas with and without information, ie read out across the surface, across the depth profile or across surface and depth profile In addition, exposed and unexposed areas differ with regard to their luminescence. In contrast to crosslinked areas, exposed areas preferably show a pronounced luminescence. A luminescence in the range of 400-600 nm with excitation wavelengths is particularly preferred from 200 to 500 nm and very particularly preferably in the range from 300 to 400 nm. This makes it possible to read out the information by excitation with a light source with a preferred emission range of 200-500 nm, very particularly preferably from 300-400 nm. All light sources with a suitable emission spectrum are therefore suitable, particularly preferably UV mercury lamps and lasers. It is also possible, for example, by means of 2-photon fluorescence spectroscopy, for example in the multi-layer various coatings in the different layers of the coating, which in turn are intended for different recipients.

In a further embodiment, the invention thus relates to the use of at least one polymer composition as a data recording medium, the polymer composition being applied to a carrier, in particular to labels, adhesive tapes, foils (smart labels), lacquered or metallic surfaces (smart coatings) a crosslinking pattern is then introduced into the coating in a spatially resolved manner by irradiation with high-energy radiation, in particular UV light, and finally this crosslinking pattern is read out.

In particular, the polymer is applied from the melt, as a solution or aqueous dispersion to the support; in the case of the solution or aqueous dispersion, the solvent or water is removed, the polymer is then irradiated with high-energy radiation, in particular UV light, and thus irradiated with space information is introduced into the polymer in a spatially resolved manner and this information is then read out.

In the context of the present invention, it is also possible that exposed and unexposed areas differ in terms of the fluorescence intensity. In this case, the information is preferably read out on the basis of the local change in the fluorescence intensity.

The invention thus also relates to the use of at least one polymer composition as a data recording medium, the reading being carried out by analyzing the local change in refractive index or the change in the local infrared absorption or Raman reflection spectra or else the local change in fluorescence becomes. There are no special requirements for the irradiation or readout devices to be used, except that the device for irradiation must supply sufficient energy in a wavelength of the incident light, that on the photoinitiator used for the polymer composition (for irradiation and Readout) or fluorescence chromophore (only for reading out the information), ie is able to activate it. The laser used, for example, does not have to be tunable. It is sufficient if it supplies light of the "correct" wavelength, that is to say the one which is matched to the photoinitiator (for irradiation and reading) or fluorescence chromophore (only for reading out the information) in the required amount. The same also applies to the readout device, ie this must also be able to evaluate the corresponding delivered signals depending on the polymer or photo initiator or fluorescence chromophore used.

In order to ensure the long-term stability of the data recording medium, the layer which contains the polymer composition with radiation-active compounds must be protected. In the context of the present invention, this can be done, for example, by an additional UV-absorbing layer.

In the context of the present invention, a UV-absorbing layer is understood to be a layer which absorbs light with a wavelength <500 nm, in particular <450 nm, particularly preferably <400 nm.

In a preferred embodiment, in particular when using fluorescence chromophores, the invention accordingly relates to the use of a polymer composition as a data recording medium, the polymer composition being applied to a support, then by irradiation with high-energy radiation, in particular UV light, a crosslinking pattern is introduced into the coating in a spatially resolved manner, then an additional UV-absorbing layer is applied and finally the crosslinking pattern is read out.

In particular, the UV-absorbing layer contains a UV stabilizer, that is to say a substance that absorbs light of the corresponding wavelength.

Suitable UV stabilizers are, for example, compounds of the following classes of substances: benzophenones, benzotriazoles and HALS compounds. In particular, mention should be made of: Lowilite ^® 20, Lowilite ^® 20-S, Lowilite ^® 22, Lowilite ^® 24, Lowilite ^® 26, Lowilite ^® 27, Lowilite ^® 55, Lowilite ^® 76, Lowilite ^® 77, Lowilite ^® 63, Uvasil ^® 299 LM, Uvasil ^® 299 HM, Uvasil ^® 2000 LM, Uvasil ^® 2000 HM, Chimassorb ^® 81, Chimassorb ^® 119, Chimassorb ^® 944, Tinuvin ^® 123, Tinuvin ^® 144, Tinuvin ^® 213, Tinuvin ^® 234, Tinuvin ^® 312, Tmuvin ^® 320, Tinuvin ^® 326, Tinuvin ^® 327, Tinuvin ^® 328, Tinuvin ^® 329, Tinuvin ^® 350, Tinuvin ^® 360, Tinuvin ^® 571, Tmuvin ^® 622, Tinuvin ^® 765, Tinuvin ^® 770, Tinuvin ^® 1577, Tinuvin ^® P, Uvitex ^® OB, Uvitex ^® FP.

Mixtures of two or more UV stabilizers can also be used in the context of the present invention.

The use of acetophenone, benzophenone, derivatives of acetophenone or benzophenone or a mixture of two or more thereof in the UV-absorbing layer is particularly preferred.

The UV absorbers used absorb light with a wavelength <500 nm, in particular <450 nm, particularly preferably <400 nm. This leads to an effective shielding of the layer containing the polymer composition from UV light.

According to the invention, the UV-absorbing layer can be applied as a film, in particular as a plastic film, or as a wet coating formulation. Especially In the context of the present invention, preference is given to films, for example polyethylene terephthalate (PET) films, polycarbonate (PC) films and polyvinyl chloride (PVC) films.

The process cited above can thus be used in conventional coating compositions, e.g. UV-curable lacquers or adhesive layers of digital information, similar to a CD-ROM, are permanently stored. A possible application would then be a so-called "smart coating", in which, for example, a label up to product information can be invisibly written in by the customer, as is the case today with the generally known "bar codes" (but there for the customer / User recognizable as such) happens. In particular, car paints are conceivable, in particular the clear coats on the surface (clearcoats, topcoats) which have been provided with (one) information by the treatment outlined above. In addition, applications in the context of product security (fraud protection), counterfeit protection for credit cards and ID cards and in Kanban systems are conceivable.

Of course, several layers of the polymer composition used according to the invention can also be applied to any substrate of your choice, in which, for example, a first layer is cast and then UV irradiated and then further layers are first applied by casting and then irradiated accordingly. Such a procedure makes it possible to apply very different, in particular also at different locations or from different people, evaluable information, for example by only providing the corresponding people with the devices with the configuration that are required for the special, only for to actually provide those people with accessible information. This can be achieved in a simple manner by appropriately adapting the readout device with regard to the penetration depth that it can achieve. Furthermore, the present invention relates to a composite, at least comprising a carrier and a layer containing at least one radiation-crosslinkable polymer composition, preferably containing at least one fluorescent chromophore.

The carrier can consist, for example, of plastic, metal, glass or ceramic. In particular, plastic films, preferably UV-transparent films, such as polyester or polyamide films, polyethylene film and polypropylene films are used as supports. The use of the flexible carrier enables the composite to be used, in particular on curved surfaces.

In a preferred embodiment, the composite additionally has a UV-absorbing layer, the layer containing at least one radiation-crosslinkable polymer composition, preferably containing at least one fluorescent chromophore, between the support and the UV. absorbent layer.

In particular, the invention relates to a composite, the UV-absorbing layer containing acetophenone, benzophenone, a derivative of acetophenone or benzophenone or a mixture of two or more thereof.

In the context of the invention, a UV-transparent support, that is to say transparent at a wavelength of 200 to 400 nm, preferably from 250 ^" to 360, particularly preferably from 250 to 340, can be used so that the layer is irradiated at least one radiation-crosslinkable polymer composition, preferably containing at least one fluorescent chromophore for applying the information from the side of the support, and this side is then laminated, for example by gluing to a non-UV-transparent substrate. According to the invention, however, it is also possible that the layer containing at least one radiation-crosslinkable polymer composition, preferably containing at least one fluorescent chromophore, is applied to a non-UV-transparent support, is then irradiated and only after the information has been applied by the irradiation is the UV -absorbent layer is applied.

The invention is explained in more detail below with the aid of examples.

Examples

Polymer composition without fluorescent chromophore

A polymer layer (50 g / m) consisting of a copolymer of 60% by weight of methyl methacrylate and 40% by weight of acryloxybenzophenone (K value 50 (1% solution in THF, 21 ° C.) was removed from the melt by means of a doctor blade applied to a glass surface at a temperature of 160 ° C. and induced a spatially resolved cross-linking by means of two superimposed laser beams of a wavelength of 300 nm and read out by means of confocal Raman spectroscopy in the wavelength range from 1000 to 1700 cm ^"1. A spatial resolution of approx. + was achieved 2.5 micrometers, the spatially resolved carbonyl signal being used as a “probe” in the spectral spectrum of acryloxybenzophenone.

The networked areas also show a different refractive index depending on the degree of crosslinking.

Figure 1 shows the refractive index [n _D25 ] (plotted on the y-axis) as a function of the UV dose [mJ / cm ² ] (plotted on the x-axis). It can be seen that the sample has a different refractive index depending on the UV dose and thus on the degree of crosslinking. Polymer composition with fluorescent chromophore

A polymer layer (approx. 50 g / m) consisting of a copolymer of 50% MMA, 40% BA, 9.5% photoinitiator and 0.5% mixed in dicyanostilbene was coated on a thin glass slide and laminated with a UV-impermeable film. Using a mask and a UV source, a lettering was then written in from the slide.

A label was obtained, with the information written being able to be read out when excited with a light source by means of a locally different fluorescence intensity. The lettering was not recognizable in ordinary daylight. Only a UV light source, which is matched in terms of its emission wavelength to the absorption of the unexposed chromophore (approx. 400nm), made the lettering visible.

Claims

claims

1. Use of at least one radiation-crosslinkable polymer composition as a data recording medium.

2. Use according spoke 1, wherein the polymer composition is an adhesive or lacquer composition.

3. Use according to claim 1 or 2, wherein the polymer composition comprises at least one free-radically or ionically polymerized, radiation-crosslinkable polymer which has been formed from monomers having at least one ethylenically unsaturated group.

4. Use according to spoke 3, wherein the free-radically or ionically polymerized, radiation-crosslinkable polymer comprises at least 50% by weight of units which were formed from at least one monomer with at least one ethylenically unsaturated group.

5. Use according to one of claims 3 to 4, wherein the polymer of 50 to 99.95 wt .-% monomers with at least one ethylenically unsaturated group and 0.05 to 50 wt .-% of a radiation-activatable compound, preferably copolymer-bound, was formed.

6. Use according to spoke 5, wherein the radiation-activatable compound is acetophenone, benzophenone, a derivative of acetophenone or bezophenone or a mixture of two or more thereof and is preferably copolymer-bound.

7. Use of at least one radiation-crosslinkable polymer composition as a data recording medium according to one of the preceding claims, containing at least one fluorescent chromophore.

8. Use according to claim 7, wherein the fluorescent chromophore is coumarin, (bis) stilbene, perylene, phenanthridine, fluorene, a derivative of coumarin, (bis) stilbene, perylene, phenanthridine or fluorene or a mixture of two or more thereof, and preferably Is copolymer-bound.

9. Use according to one of the preceding claims, wherein the polymer composition is applied to a carrier, in particular on labels, adhesive tapes, foils (smart labels), painted or metallic surfaces (smart coatings), then by irradiation with high-energy radiation, in particular UV -Light, a cross-linking pattern is introduced into the coating in a spatially resolved manner and finally this cross-linking pattern is read out.

10. Use according to spoke 9, wherein a UV-absorbing layer is applied after irradiation of the coating.

11. Use according spoke 9 or 10, characterized in that the reading is carried out by analyzing the local refractive index change or the change in the local infrared absorption or Raman reflection spectra or the local change in fluorescence.

12. Composite, at least comprising a carrier and a layer containing at least one radiation-crosslinkable polymer composition containing at least one fluorescence chromophore according to one of the claims

7 or 8.

13. The composite of claim 12, wherein the carrier is a UV-transparent film.

14. Composite according to one of claims 12 or 13, wherein the composite additionally has at least one UV-absorbing layer.