WO2005032833A1

WO2005032833A1 - Recording medium

Info

Publication number: WO2005032833A1
Application number: PCT/NL2004/000690
Authority: WO
Inventors: Sebastianus Gerardus Johannes Maria Kluijtmans; Yoichiro Kamiyama
Original assignee: Fuji Photo Film B.V.
Priority date: 2003-10-03
Filing date: 2004-10-04
Publication date: 2005-04-14

Abstract

The present invention relates to a recording medium, in particular an ink-jet recording medium of photographic quality that has excellent color stability while keeping good ink absorption speed, good drying characteristics and a good image printing quality. According to the present invention an ink-jet recording medium is provided, comprising a support and an ink-receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising a water-soluble polypeptide to which dye stabilizing functional groups are covalently linked. The present invention is further directed to methods for obtaining and using such a medium.

Description

Title: Recording medium

Field of the invention The present invention relates generally to a recording medium, in particular an ink -jet recording medium of photographic quality that has excellent ink absorption speed, good drying characteristics and a good image printing quality, in particular a good lightfastness and whiteness, as well as to methods for preparing and using such media.

Background of the invention In a typical ink-jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye, and a relatively large amount of solvent in order to prevent clogging of the nozzle. The solvent, or carrier liquid, typically is made up of water, and organic material such as monohydric alcohols and the like. An image recorded as liquid droplets requires a receptor on which the recording liquid dries quickly without running or spreading. High quality image reproduction using ink -jet printing techniques requires receptor substrates, typically sheets of paper or opaque or transparent film, that readily absorb ink droplets while preventing droplet diffusion or migration. Good absorption of ink encourages image drying while minimizing dye migration by which good sharpness of the recorded image is obtained. A further important property of inkjet media is that they should provide for a good lightfastness, viz. the printed images must not fade over a longer period of time. DE-A-223 48 23 and US-A-4 379 804 disclose methods in which gelatin is used in ink-receiving layers of ink-jet receiving sheets. From these documents, it has become clear that gelatin has an advantageous function, e.g. for the absorption of ink solvents but is still lacking in providing sufficient dye stability especially when exposed to light. GB-B-2 088 777 describes the addition of dye image fading preventing agents, like phenol- or bisphenol — derivatives that are alkyl substituted in at least one ortho position relative to the hydroxy group, in combination with UN absorbing compounds, but these agents and compounds require the application of an oil-in-water emulsion. Also, for example, EP-A-0 280 650 and EP-A-0 738 718 describe specific hydroxyphenylbenzo- triazoles as UN-stabilisers, but these also require an oil in water emulsion. WO-A-02/55617 attempts to improve dye stability by adding a solubilized hydroquinone but is silent with respect to disadvantages of using water soluble stabilizers, like unwanted diffusion and crystallisation. The use of optical brighteners to improve whiteness of recording materials is common in the art. US-B-4 620 197 describes the application of a water soluble optical brightener directly on a base paper, but has no further ink receiving layers. US-B-4 680 235 and US-B-4 686 118 mention that an ink receiving layer may contain, amongst others, an optical brightener or fluorescent dye but do not teach how these are used and are silent with respect to any problems related to the use of these substances. EP-A-0 280 650 and EP-A-0 856 414 mention that additives, for example fluorescent brighteners, can be added in ink receiving layers containing UN-absorbers but are silent with respect to drawbacks of the combined use of these. Although the abovementioned prior art documents may contribute to improved lightfastness, in general the suggested measures give rise to a paper having less whiteness, especially after aging. Thus there remains a need for ink-jet materials having good lightfastness combined with acceptable whiteness. At the same time this material should provide for good image printing quality, good drying properties, good curl and brittleness, having at the same time good behaviour on bleed, beading and matte appearance at high density parts and also be available at low cost. It is towards fulfilling these needs that the present invention is directed.

Summary of the invention The object of the present invention is thus to provide a recording medium having good overall properties, said material more in particular being suited to produce images of photographic quality, wherein said medium has an improved lightfastness and whiteness. At the same time it is desirable that the media of the present invention maintain other favourable properties with respect to brittleness at low humidities, curling behaviour, beading, matt appearance at high densities and has good bleeding properties. It has been found that these objectives can be met by providing a recording medium comprising a support and an ink -receiving layer adhered to said support, where the ink receiving layer is a multilayer,.comprising a water- soluble polypeptide, which has been chemically modified by coupling specific functional groups thereto. Thus a functionalized polypeptide is obtained.

Detailed description The invention is directed to a recording medium comprising a support and an ink-receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising a water-soluble polypeptide to which specific functional groups are covalently linked. These functional groups can be for example dye-stabilizing groups, like UN-absorbing compounds or anti- oxidants, or optical brighteners. This invention is also related to the manufacturing of such a recording medium and the use of this medium. Both the overlayer and the underlayer of this invention may be a multilayer of sublayers. The total number of sublayers is not particularly limited and depends largely on the available technique for application of layers and the required ink receiving properties of the ink receiving layer. The total number of sublayers may be from 2 to 25, more preferably from 3 to 17. In the conventional media for ink jet application comprising at least one ink receiving layer based on a water soluble polymer, such as gelatin, polyvinyl alcohol (PNA), PEO, hydroxyethylcellulose and the like and mixtures of these polymers, it is possible to obtain good drying characteristics but it is difficult to obtain an image with photographic quality due to the color instability of the printed image. We have now surprisingly found that the color stability can be improved significantly by using a medium on which the ink receiving layer is a multilayer, at least comprising an underlayer and an overlayer, wherein at least one layer comprises a polypeptide to which dye stabilizing functional groups, such as UN absorbing groups, anti-oxidant groups and optical brightening groups, are covalently linked. Linking of groups such as UV-absorbing groups, anti-oxidant groups or optical brightening groups to a polypeptide such as e.g. gelatin prevents - migration of these groups. Migration of UN-absorbers to the toplayer, as can occur with solubilized UN-absorbers, has been found to cause problems, since the solubilized UN-absorber may crystallize on or near the surface. On the other hand, migration of water soluble anti-oxidants away from the layer containing the printed dye reduces the effectiveness of the anti-oxidant. Optical brighteners are compounds that absorb UN light between 300 and 400 nm and have a strong fluorescence in the blue region of the spectrum. Optical brighteners are preferably located further away from the substrate on which the ink receiving layer is coated than the UN absorber. In this manner brightening is more effective and the optical brightener also serves as a UN absorber. When using water soluble agents localization of these agents in a specific layer is not possible. By this the efficiency of these water soluble agents is negatively influenced. One possibility is to use oil-in-water emulsions comprising oil-soluble UN absorbers and optical brighteners. Even in this case crystallization can occur especially at high temperature and high humidities, while it is more difficult to prevent phase separation of the polymers used in the ink receiving layer, like for example gelatin and polyethyleneoxide. The polypeptides of the invention are particularly suited for the purpose of restricting functional groups to a specific layer within the ink- receiving multilayer. Suitable polypeptides for covalent linking of functional groups are water-soluble polypeptides selected from the group consisting of casein, sericin, soluble collagen and gelatin or derivatives thereof. It is also possible to link functional groups to other water-soluble polymers like polyvinyl pyrrolidone, polyacrylamide, polyvinylimidazole, polyvinylpyrazole, cellulose derivatives and saccharide derivatives. Covalent linking of functional groups to amine groups of gelatin for photographic purposes is described in EP-A-1 172 399, incorporated herein by reference in its entirety. In general, the functional groups are coupled to the amine groups of the water-soluble polypeptide by providing a mixture of the polypeptide, typically an aqueous mixture, and adding a compound, which bears the functional group linked to a suitable coupling group, which coupling group can be used to form a covalent bond between the polypeptide and the functional group. The chemical linking between activated carboxylic acid groups of a functional groups with the free amine groups of the water-soluble polypeptide (like the pendant amine groups (lysine and hydroxy-lysine) of gelatin) is a well known synthesis route for the production of an amide, as is shown in disclosure EP-A-0 576 911. The activation of the carboxylic acid groups of the functional molecules can be carried out by various methods. For example, the method of N-hydroxysuccinimide (NHS) / di-cyclohexyl carbodiimide (DCC) in an organic solvent, such as acetonitril, tetrahydrofuran, 1,3-dioxane or 1,4- dioxane, preferably tetrahydrofuran, can be used for activation. Another way to produce an amide is by linking the (activated) carboxylic acid end groups of gelatin amino acids (glutamine and asparagine) to the amine -moieties of the functional groups. Although many functional groups can be coupled to gelatin, the present invention is particularly directed to the coupling of functional groups that improve dye stability in inkjet applications like UN-absorbing groups, anti-oxidants and optical brighteners. The amount of functional groups linked to gelatin is preferably between 10 and 120 mmol per gram gelatin, more preferably the amount of linked groups is higher than 20 mmol per gram, even more preferably higher than 40 mmol per gram and still more preferably between 50 and 100 mmol per gram gelatin or other type of water-soluble polypeptide. Suitable UN-absorbing groups are disclosed e.g. in research disclosures: RD24239, RD290119, RD30326 and comprise the families of cinnamates, hydroxybenzophenones, benzotriazoles and aminobutadienes or a combination thereof. Preferred UN-absorbers are benzotriazoles, more preferably hydroxyphenylbenzotriazoles. Preferably the UN absorbing groups absorb at a wavelength of less than 400 nm. Less preferred are UN absorbing groups of which the absorption extends somewhat beyond 400 nm, since these can have a yellowish color. The UN-absorber is preferably present in the ink receiving layer in an amount of 0.1 to 5.0 gram/m², preferably of 0.2 to 1.0 gram/m², based on the weight of the UN-absorbing moieties that have been linked to the gelatin or other type of water-soluble polypeptide. Suitable anti-oxidants that can also be covalently linked to gelatin or other type of water-soluble polypeptide are disclosed in e.g. RD31980, RD31429, RD30326 and comprise substituted phenolic and blocked phenolic compounds, phenolic thiane derivatives, substituted bisphenols, sterically hindered amines, hydrochinon and agents having molecular structures which are based upon a cresol type of molecule, a pyrogallol type, a cathechol type, or a 2,4-disulphonamidophenol type. Preferably 1,4-dihydroxybenzenes are covalently linked to gelatin. The anti-oxidant is suitably present in the ink receiving layer in an amount of 0.05 to 2.5 gram/m², preferably of 0.1 to 1.0 gram/m², based on the weight of the anti-oxidant moieties that have been linked to the gelatin or other type of water-soluble polypeptide. Suitable optical brighteners that can be covalently linked to gelatin are disclosed in e.g. RD11125, RD9310, RD8727, RD8407, RD36544 and comprise thiophenes, stilbenes, triazines, imidazolones, pyrazolines, triazoles and acetylenes. The optical brightener is suitably present in the ink receiving layer in an amount of 0.01 to 5.0 gram/m², preferably of 0.1 to 1.0 gram/m², based on the weight of the optical brightener moieties that have been linked to the gelatin or other type of water-soluble polypeptide. Modified gelatins in which the amount of free amine groups has been increased can be used to increase tl e load of functional groups like UN- absorbers or anti-oxidants on the gelatin. EP-A-0 487 686 describes a method to convert carboxyl groups into amines. Spacers can be used to increase the amount of free reactive groups on gelatin. A spacer is a molecule which can be covalently linked to reactive groups of gelatin, like carboxyl groups or amine groups, said spacer molecule containing at least two reactive groups like amine groups, thus increasing the amount of available active groups. Spacer molecules are exemplified by amino acids like lysine, glutamic acid or aspartic acid, but are not limited to such structures. In one embodiment gelatins or other type of water-soluble polypeptide to which UN-absorbing groups are linked and gelatins to which anti-oxidants are linked are combined in the ink receiving layer. It also possible to link both UN-absorber groups and anti-oxidant groups to a gelatin. In an other embodiment the gelatin or other type of water-soluble polypeptide is linked with UN-absorber groups and/or anti-oxidant groups and/or an additional functional group like an optical brightener The gelatin or other type of water-soluble polypeptide to which functional groups have been linked can be added in any of the layers comprised in the ink-receiving layer, but preferably it is added in the layer(s) where the dye is fixed upon use of the medium. In a preferred embodiment the ink-receiving layer comprises at least one underlayer, at least one dye- stabilizing layer on top (when referring to relative locations of the layers in the present description and claims, it is assumed that the medium is oriented such that the support is its downside) of the underlayer(s) and an overlayer on top of the stabilizing layer. The dye-stabilizing layer(s) comprise the gelatin or other type of water-soluble polypeptide linked with UN-absorbing groups and/or anti-oxidant groups and can further comprise any component that is also used in an underlayer. The compositions of and modifications to the underlayer(s) as discussed herein, also apply to the dye-stabilizing layers in other words the dye-stabilizing layer can be regarded as (one of) the underlaye (s). Although in most cases an overlayer will be present on top of the dye-stabilizing layer in a specific embodiment the overlayer comprises a water-soluble polypeptide to which dye -stabilizing functional groups are covalently linked. So in this embodiment the overlayer is a dye-stabilizing layer. In another embodiment the ink-receiving layer comprises at least one underlayer, a dye stabilizing layer on top of the underlayer(s), at least one optical brightener layer on top of the dye stabilizing layer(s) and an overlayer on top of the optical brightener layer (s). The optical brightening layer(s) comprise the gelatin or other type of water-soluble polypeptide linked with optical brightener groups and can further comprise any component that is also used in an underlayer or overlayer. When discussing further embodiments of the underlayer(s) or overlayer(s) these also include optical brightening layers. It was found that in case the underlayer is a multilayer it is beneficial to apply different concentrations of gelatin and water soluble polymer in the sublayers of the underlayer. A lower concentration of gelatin and water soluble polymer in the sublayer closest to the support enables a lower viscosity of the mixture which improves the coatability and allows higher coating speeds. In a specific embodiment an adhesion promoting layer is applied between the support and the underlayer to enhance the adhesion of the coated layers onto the support. This adhesion promoting layer may be coated in a separate step or simultaneously with the receiving layers. In the ink receiving layer, the underlayer can comprise any combination of polymers with gelatin known in the art as described for example in EP-A-0 594 896. There is a variety of gelatins, both non-modified as well as modified gelatins which can be used in the underlayer. Examples of non-modified gelatins are alkali-treated gelatin (cattle bone or hide gelatin), acid-treated gelatin (pigskin, cattle/pig bone gelatin), or hydrolyzed gelatin. Examples of modified gelatins are acetylated gelatin, phthalated gelatin, quaternary ammonium modified gelatin, et cetera. These gelatins can be used singly or in combination for forming the underlayer. Acid and alkali treated gelatins are preferred. Also recombinant gelatins, like for example described in WO-A- 02/052342, can be applied. Water soluble polymers suitable to be mixed with the (modified) gelatin include polyvinyl alcohol- (PNA-)based polymers, such as fully hydrolysed or partially hydrolysed polyvinyl alcohol (PVA), carboxylated polyvinyl alcohol, copolymers and terpolymers of PNA with other polymers, water soluble cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, carboxy methyl cellulose, casein, gum arabic, polyacrylic acid and its copolymers or terpolymers, and any other polymers, which contain monomers of carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and crotonic acid, polyvinylpyrolidone (PNP), polyethylene oxide, polyacrylamide, 2-pyrrolidone and its derivatives such as Ν (2- hydroxyethyl)-2-pyrrolidone and Ν-cyclohexyl-2-pyrrolidone, urea and its derivatives such as imidazolidinyl urea, diazolidinyl urea, 2-hydroxy- ethylethylene urea, and ethylene urea. There are water soluble polymers that have very limited compatibility with gelatin. These polymers include fully hydrolyzed or partially hydrolyzed polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyethylene oxide, polyacrylamide, and the like. When a solution of gelatin in water is mixed with a solution in water of one of the above described polymers, micro or macro phase separation occurs in solution which persists in the dried coating. The dried coating exhibits high haze, low transparency, and low gloss. The system of a mixture of gelatin and a water soluble polymer is very well illustrated by means of a gelatin/PEO mixture as example. A homogeneous gelatin PEO mixture, i.e. a mixture where no phase separation occurs, may be obtained by adjusting the pH of the mixture. However there is no unique rule to determine the pH at which there is no phase separation. The best way is to follow the practical approach by making the required mixture of gelatin and water soluble polymer in water and adding alkali or acid until a homogeneous solution is obtained. The suitable pH range mainly depends on the gelatin type used and type of the water soluble polymer. It was found that modified acid treated gelatins having an iso-electric-point (IEP) of between 6 and 11 give a homogeneous solution with polyethylene oxide (PEO) at a pH below 5. At pH between 5 and 10, the mixture remains turbid, which indicate that the mixture is not homogeneous. At a pH higher than 11, a homogeneous solution can be obtained. For a lime treated gelatin, that may have an IEP value of between 4 and 6, a homogeneous mixture between gelatin and PEO can be obtained at a broader pH ranges, i.e. at a pH value lower than 4.5 or at a pH value higher than 6. In addition to the above mentioned pH adjustment, we have found, that it is not only important to have a homogeneous solution, but it is also beneficial to have a molecular weight of PEO of at least 100 000. A lower MW might also give satisfactory results, but in general most of the important properties, like curling, drying speed and brittleness improve when using a high MW PEO. In addition to this, it appeared to be beneficial to use an underlayer comprising various layers, in which the various layers have a different gelatin/PEO ratio. We have found that a low gelatin/PEO ratio in the layer adjacent to the overlayer and a higher gelatin/PEO ratio at the layers nearer to the support have a beneficial effect on properties like bleeding and beading. More specifically gelatin/PEO ratio's (wt./wt.) in the layer nearest to the overlayer preferably vary between 1/1 to 8/1 and the gelatin/PEO ratios (wt./wt.) in the layers nearest to the support should vary between 1/1 and 12/1 with the condition, that the gelatin/PEO ratio of the layer adjacent to the overlayer is always lower, than the ratio of the other gelatin-PEO layers. When using more gelatin-PEO layers in the underlayer it is further beneficial to use a gradient for the gelatin/PEO ratio, meaning, that the gelatin/PEO ratio is lowest in the layer adjacent to the overlayer and said ratio is highest for the layer most near to the substrate. The homogeneous gelatin-PEO solution of the underlayer, which is supplied to the substrate preferably has a gelatin concentration between 5 and 20 wt.%. Embodiments are described using PEO. Similar embodiments can be made using mixtures of gelatin and other water soluble polymers having a limited compatibility with each other. One may substitute the PEO with other water soluble polymers mentioned above such as PVP or PNA or a mixture between two or more water soluble polymers such as PEO and PNP. The ratio between the gelatin and said water soluble polymer(s) is preferably in the same ranges as described above for gelatin/PEO system. Good results are obtained with PNA-based polymers. In general a large variety of PNA-based polymers can be used, but the preferred PNA-based polymers are those which have been modified to give a good miscibility with aqueous gelatin solutions. These modifications are such, that in the PNA-based polymer back bone groups are introduced which provide a hydrogen bonding site, an ionic bonding site, carboxylic groups, sulphonyl groups, amide groups and the like, thus providing a modified PNA-based polymer. A modified PNA- based polymer giving very good results is a poly(vinyl alcohol)-co-poly(n-vinyl formamide) copolymer (PNA-ΝNF). Nery suitable PNA-ΝNF copolymers for use with the present invention are the copolymers described in WO-A-03/054029, which have the general formula I:

wherein n is between 0 and about 20 mole percent; m is between about 50 and about 97 mole percent; x is between 0 and about 20 mole percent; y is between 0 and about 20 mole percent; z is between 0 and about 2 mole percent and x+y is between about 3 and about 20 mole percent; Ri, and R₃ are independently H, 3-propionic acid or Ci-Ce alkyl ester thereof, or is 2-methyl-3-propionic acid or Ci-Ce alkyl ester thereof; and R₂ and R₄ are independently H or Ci-Cβ alkyl. The water soluble polymer is preferably applied for the underlayer in an amount ranging from 0.5 to 15 g/m², more preferably from 1.0 to 8.0 g/m². The overlayer or toplayer is important for surface properties like beading and gloss. The overlayer preferably comprises a modified gelatin, and may further comprise water insoluble particles inter alia to regulate the slip behaviour and optionally one or more water soluble polymers, surfactants and other additives to optimise the surface properties. A variety of modified gelatins can be used in the overlayer. Good results are obtained, when at least 30% of the NH₂ groups of the gelatin is modified by a condensation reaction with a compound having at least one carboxylic group as described among others in DE-A-19721238. The compound having at least one carboxylic group can have an other functional group like a second carboxylic group and a long aliphatic tail, which in principle is not modified. Long tail in this context means from at least 5 to as much as 25 C atoms. This aliphatic chain can be modified still to adjust the properties like water solubility and ink receptivity. Preferred modified gelatins comprise an alkyl group (more preferably a Cδ-C25-alkyl group), a fatty acid group (more preferably C5-C₂5-fatty acid group), or both. Even more preferably the gelatins comprise a C₇-Ci8-alkyl group, a Cγ-Cis-fatty acid group, or both. Especially preferred gelatins of this type are succmic acid modified gelatins in which the succinic acid moiety contains an aliphatic chain from at least 5 to 25 carbon- atoms, where the chain can still be modified to a certain extend to adjust the water soluble properties or ink receptive properties. Most preferred is the use of docecenylsuccinic acid modified gelatin, in which at least 30% of the NH₂ groups of the gelatin have been modified with said dodecenylsuccinic acid. Other suitable methods for obtaining the modified gelatin, which may be functionalized according to the present invention, are described in EP-A- 0 56 911, by V.N. Izmailova, et al. (Colloid Journal, vol. 64, No. 5, 2002, page 640-642), and by O. Toledano, et al. (Journal of Colloid and Interface Science 200, page 235-240). Other suitable modified gelatins giving good results are gelatins modified to have quaternary ammonium groups. An example of such a gelatin is the "Croquat™" gelatin produced by Croda Colloids Ltd. Still another modified gelatin known in the common gelatin technology, such as phtalated gelatin and acetylated gelatins are also suitable to be used in the overlayer. The functionalized gelatin can be used alone or in combination with another water soluble polymer. Examples of these polymers include: fully hydrolysed or partially hydrolysed polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, any gelatin whether lime -processed or acid processed made from animal collagen, preferably gelatin made from pig skin, cow skin or cow bone, polyethylene oxide, polyacrylamide, and the like. The modified gelatin is suitably applied in the overlayer preferably in an amount ranging from 0.3 to 5 g/m², most preferably from 0.5 to 3 g/m². Suitable amounts of the water soluble polymer in the mixture vary between 0 and 75 wt% of the amount of the modified gelatin. In case said water soluble polymer amount is higher than 75 wt%, the advantages of the modified gelatin may become less pronounced. The mere application of the modified gelatin or mix of modified gelatin and water soluble polymers improves the characteristics with respect to drying and finger smearing properties. A further improvement of above mentioned properties can be obtained by including in the overlayer a fluoro surfactant in the amount between 2.5 mg/m² and 250 mg/m². This kind of surfactants improves amongst others the gloss and beading. Beading is defined as the phenomenon that large ink dots become visible on the printed image. The mechanism of "beading" is not clear yet. One hypothesis is that several small ink drops coalesce with each other on the surface of the ink jet media and form large ink droplets. The term "fluorosurfactant" as used herein, refers to surfactants (viz. molecules having a hydrophilic and a hydrophobic part) that contain fluorocarbon or a combination between fluorocarbon and hydrocarbon as the hydrophobic part. Suitable fluorosurfactants may be anionic, non-ionic or cationic. Examples of suitable fluorosurfactants are: fluoro C2-C20 alky lcarboxy lie acids and salts thereof, disodium N-perfluorooctanesulfonyl glutamate, sodium 3-(fluoro-C6-Cn alkyloxy)-l-C3-C₄ alkyl sulfonates, sodium 3-(omega -fluoro-Ce-Cs alkanoyl-N-ethylamino)-l-propane sulfonates, N-[3- (perfluorooctanesulfonamide)-propyl]-N,N-dimethyl-N-carboxymethylene ammonium betaine, perfluoro alkyl carboxylic acids (e.g. perfluoro C7-C13 alkyl carboxylic acids) and salts thereof, perfluorooctane sulfonic acid diethanolamide, Li, K and Na perfluoro C4-C12 alkyl sulfonates, Li, K and Na N-perfluoro C4-C13 alkane sulfonyl -N- alkyl glycine, fluorosurfactants commercially available under the name Zonyl^® (produced by E.I. Du Pont) that have the chemical structure of RfCH2CH2SCH2CH2C0₂Li or RfCH₂CH2θ(CH2CH2θ) H wherein R_f = F(CF₂CF₂)3-8 and x = 0 to 25, N- propyl-N-(2-hydroxyethyl)perfluorooctane sulfonamide, 2-sulfo-l,4- bis(fluoroalkyl)butanedioate, 1,4-bis (fiuoroalkyl)-2-[2-N,N,N- trialkylammonium) alkyl amino] butanedioate, perfluoro Ce-Cio alkylsulfonamide propyl sulfonyl glycinates, bis-(N-perfluorooctylsulfonyl-N- ethanolaminoethyl)phosphonate, mono-perfluoro Ce-Ciβ alkyl-ethyl phosphonates, and perfluoroalkylbetaine. Also useful are the fluorocarbon surfactants described e.g. in US-A-4 781 985 and in US-A-5 084 340. Preferably the fluorosurfactant is chosen from Li, K and Na N-perfluoro C4-C13 alkane sulfonyl — N- alkyl glycine, 2-sulfo-l,4-bis(fluoroalkyl)butanedioate, 1,4-bis (fluoroalkyl)-2-[2-(N,N,N- trialkylammonium alkyl amino] butanedioate, perfluoroalkyl subsitituted carboxylic acids commercially available under the name Lodyne^® (produced by Ciba Specialty Chemicals Corp.) and fluorosurfactants commercially available under the name Zonyl^® (produced by E.I. Du Pont) that have the chemical structure of R_fCH2CH2SCH2CH2C0₂Li or R CH2CH2θ(CH₂CH2θ) H wherein R_f = F(CF₂CF₂)3-8 and x = 0 to 25. Beside the modified gelatin or modified gelatin/water soluble polymer mixture and fluorosurfactant it may be desirable to add in the overlayer an anti-blocking agent to prevent image transfer when several printed inkjet mediums are piled up. Very suitable anti-blocking agents (also known as matting agents) have a particle size from 1 to 20 μm, preferably between 2 and 10 μm. The amount of matting agent is from 0.01 to 1 g/m², preferably from 0.02 to 0.5 g/m². The matting agent can be defined as particles of inorganic or organic materials capable of being dispersed in a hydrophilic organic colloid. The inorganic matting agents include oxides such as silicon oxide, titanium oxide, magnesium oxide and aluminium oxide, alkali earth metal salts such as barium sulphate, calcium carbonate, and magnesium sulphate, and glass particles. Besides these substances one may select inorganic matting agents which are disclosed in West German Patent No. 2,529,321, British Patent Nos. 760,775 and 1,260,772, U.S. Pat. Nos. 1,201,905, 2,192,241, 3,053,662, 3,062,649, 3,257,296, 3,322,555, 3,353,958, 3,370,951, 3,411,907, 3,437,484, 3,.523,022, 3,615,554, 3,635,714, 3,769,020, 4,021,245 and 4,029,504. The organic matting agents include starch, cellulose esters such as cellulose acetate propionate, cellulose ethers such as ethyl cellulose, and synthetic resins. The synthetic resins are water insoluble or sparingly soluble polymers which include a polymer of an alkyl(meth)acrylate, an alkoxyalkyl(meth) aery late, a glycidyl(meth)acrylate, a (meth)acrylamide, a vinyl ester such as vinyl acetate, acrylonitrile, an olefin such as ethylene, or styrene and a copolymer of the above described monomer with other monomers such as acrylic acid, methacrylic acid, alpha, beta -unsaturated dicarboxylic acid, hydroxyalkyl(meth)acrylate, sulfoalkyl(meth)acrylate and styrene sulfonic acid. Further, a benzoguanamin-formaldehyde resin, an epoxy resin, nylon, polycarbonates, phenol resins, polyvinyl carbazol or polyvinylidene chloride can be used. Besides the above are used organic matting agents which are disclosed in British Patent No. 1,055,713, U.S. Pat. Nos. 1,939,213, 2,221,873, 2,268,662, 2,322,037, 2,376,005, 2,391,181, 2,701,245, 2,992,101, 3,079,257, 3,262,782, 3,443,946, 3, 516,832, 3,539,344,554, 3,591,379, 3,754,924 and 3,767,448, Japanese Patent O.P.L Publication Nos. 49- 106821/1974 and 57-14835/1982. These matting agents may be used alone or in combination. The overlayer may optionally include thickener agents, biocides crosslinking agents and further various conventional additives such as colorants, colored pigments, pigment dispersants, mold lubricants, permeating agents, fixing agents for ink dyes, dispersing agents, anti-foaming agents, leveling agents, fluidity improving agents, antiseptic agents, brightening agents, viscosity stabilizing and/or enhancing agents, pH adjusting agents, anti-mildew agents, anti-fungal agents, agents for moisture -proofing, agents for increasing the stiffness of wet paper, agents for increasing the stiffness of dry paper and anti-static agents. The above-mentioned various additives can be added ordinarily in a range of 0 to 10 weight % expressed as total additive based on the solid content of the ink receiving layer composition. In another embodiment the modified gelatin and the fluorosurfactant can be added in separate overlayer coatings, meaning, that also the overlayer is a multilayer. In this case it is preferable to have the fluorosurfactant in a coating layer farthest away from the substrate and the modified gelatin applied under this coating. The ink receiving layer may further contain the following ingredients in order to improve its properties with respect to ink receptivity and strength: - One or more plasticizers, such as ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, glycerol monomethylether, glycerol monochlorohydrin, ethylene carbonate, propylene carbonate, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, urea phosphate, triphenylphosphate, glycerolmonostearate, propylene glycol monostearate, tetramethylene sulfone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, and polymer lattices with low Tg-value such as polyethylacrylate, polymethylacrylate and the like. - One or more fillers; both organic and inorganic particles can be used as fillers. Useful filler examples are represented by silica (colloidal silica), alumina or alumina hydrate (aluminazol, colloidal alumina, a cat ion aluminum oxide or its hydrate and pseudo-boehmite), a surface-processed cat ion colloidal silica, aluminum silicate, magnesium silicate, magnesium carbonate, titanium dioxide, zinc oxide, calcium carbonate, kaolin, talc, clay, zinc carbonate, satin white, diatomaceous earth, synthetic amorphous silica, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide and synthetic mica. Useful examples of organic fillers are represented by polystyrene, poly me thacry late, polymethyl-methacrylate, elastomers, ethylene-vinyl acetate copolymers, polyesters, pol ester-copolymers, polyacrylates, polyvinylethers, polyamides, polyolefins, polysilicones, guanamine resins, polytetrafluoroethylene, elastomeric styrene-butadiene rubber (SBR), urea resins, urea-formalin resins. Such organic and inorganic fillers may be used alone or in combination. - One or more mordants. Mordants may be incorporated in the ink- receptive layer of the present invention. Such mordants are represented by cationic compounds, monomeric or polymeric, capable of complexing with the dyes used in the ink compositions. Useful examples of such mordants include quaternary ammonium block copolymers. Other suitable mordants comprise diamino alkanes, ammonium quaternary salts and quaternary acrylic copolymer latexes. Other suitable mordants are fluoro compounds, such as tetra ammonium fluoride hydrate, 2,2,2-trifluoroethylamine hydrochloride, 1- (alpha, alpha, alpha -trifluoro-m-tolyl) piperazine hydrochloride, 4-bromo- alpha, alpha, alpha -trifluoro-o-toluidine hydrochloride, difluorophenylhydrazine hydrochloride, 4-fluorobenzylamine hydrochloride, 4- fluoro- alpha, alpha -dimeth lphenethylamine hydrochloride, 2- fluoroethylaminehydrochloride, 2-fluoro- 1-methyl pyridinium-toluene sulfonate, 4-fluorophenethylamine hydrochloride, fluorophenylhydrazine hydrochloride, l-(2-fluorophenyl) piperazine monohydrochloride, 1 -fluoro pyridinium trifiuoromethane sulfonate. - One or more conventional additives, such as: • pigments: white pigments such as titanium oxide, zinc oxide, talc, calcium carbonate and the like; blue pigments or dyes such as cobalt blue, ultramarine or phthalocyanine blue; magenta pigments or dyes such as cobalt violet, fast violet or manganese violet; • biocides; • pH controllers; • preservatives; • viscosity modifiers; • dispersing agents; • light stabilising agents • antistatic agents; and/or • anionic, cationic, non-ionic, and/or amphoteric surfactants, typically used in amounts ranging from 0.1 to 1000 mg/m², preferably from 0.5 to 100 mg/m². These additives may be selected from known compounds and materials in accordance with the objects to be achieved. The above-mentioned additives (plasticizers, fillers/pigments, mordants, conventional additives) may be added in a range of 0 to 30% by weight, based on the solid content of the water soluble polymers and / or gelatin in the underlayer. The particle sizes of the non water-soluble particulate additives should not be too high, since otherwise a negative influence on the resulting surface will be obtained. The used particle size should therefore preferably be less than 10 μm, more preferably 7 μm or less. The particle size is preferably above 0.1 μm, more preferably about 1 μm or more for handling purposes. The gelatin is preferably used in a total amount of from 1 to 30 g/m², and more preferably from 2 to 20 g/m². The amount of hydrophilic polymer used in a certain formulation can be easily calculated from the indicated amount of gelatin and is typically in the range from 100 mg/m² to 30 g/m² and more preferably between 200 mg/m² and 20 g/m². When preparing the ink -jet- receiving sheet by coating a plurality of layers, each layer comprises an amount of gelatin ranging from 0.5 to 10 g/m². If desired, the gelatin can be cross-linked in the image-recording elements of the present invention in order to impart mechanical strength to the layer. This can be done by any cross-linking agent known in the art. For gelatin, there is a large number of known cross-linking agents- also known as hardening agents. Examples of the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedion, bis (2-chloroethylurea), 2-hydroxy-4, 6- dichloro-l,3,5-triazine, reactive halogen-containing compounds disclosed in US-A-3 288 775, carbamoyl pyridinium compounds in which the pyridine ring carries a sulphate or an alkyl sulphate group disclosed in US-A-4 063 952 and US-A-5 529 892, divinylsulfones, and the like. These hardeners can be used singly or in combination. The amount of hardener used, preferably ranges from 0.1 to 10 g, and more preferably from 0.1 to 7 g based on 100 g of gelatin contained in the ink-receiving layer. For PNA, for example, it is preferable to choose a cross-linking agent selected from borax, glyoxal, dicarboxylic acids and the like. The process for preparing an ink -jet recording medium according to the invention comprises the steps of: providing a mixture of a water-soluble polypeptide, preferably an aqueous mixture, and providing one or more compounds having a dye- stabilization functional group, which is linked to a coupling group and subsequently adding said compound(s) to said mixture and reacting said coupling group with at least a portion of the amino groups in said polypeptide as to form a covalent bond between said polypeptide and said functional group, by which a solution of a dye-stabilization functionalized polypeptide is obtained, preparing at least one aqueous mixture for the overlayer, preparing at least one aqueous mixture for the underlaye (s), adding said solution of a functionalized polypeptide to one or more of the mixtures for the overlayer or the underlayer (s) by which mixture (s) for a dye- stabilizing layer is formed. The resulting formulations for the overlayer(s), dye-stabilizing layer(s) and underlayer(s) can be coated consecutively or simultaneously to a support by any method known in the art. The coating methods are for example, a curtain coating, an extrusion coating, an air-knife coating, a slide coating, a roll coating method, reverse roll coating, dip coating processes and a rod bar coating. The support used in this invention may suitably be selected from a paper, a photographic base paper, a paper coated on both sides with a polymer layer, pigment coated paper, a synthetic paper or a plastic film in which the top and back coatings are balanced in order to minimise the curl behaviour. The backside coating comprises gelatin or a water soluble polymer in an amount ranging preferably from 1 to 20 g/m², more preferably from 4 to 15 g/m². The optimum amount of the backside coating depends on the type of gelatin, the type of water soluble polymer and on the composition of the layers at the ink receiving side of the medium and is determined experimentally. The preferred polymer for the backside coating is gelatin. An important characteristic of the inkjet recording medium is the gloss. It has been found that the gloss of the medium can be improved by selecting the appropriate surface roughness of the used support. It was found, that providing a support having a surface roughness characterised by the value Ra being less than 1.0 μm, preferably below 0.8 μm a very glossy medium can be obtained. A low value of the Ra indicates a smooth surface. The Ra is measured according to DIN 4776; software package version 1.62 with the following settings:

(1) Point density 500 P/mm (2) Area 5.6 x 4.0 mm² (3) Cut-off wavelength 0.80 mm (4) Speed 0.5 mm/sec, using a UBM equipment. The base paper to be used as the support for the present invention is selected from materials conventionally used in high quality printing paper. Generally it is based on natural wood pulp and if desired, a filler such as talc, calcium carbonate, Tiθ2, BaSθ4, and the like can be added. Generally the paper also contains internal sizing agents, such as alkyl ketene dimer, higher fatty acids, paraffin wax, alkenylsuccinic acid, epichlorhydrin fatty acid amid and the like. Further the paper may contain wet and dry strength agents such as a polyamine, a poly-amide, polyacrylamide, poly-epichlorhydrin or starch and the like. Further additives in the paper can be fixing agents, such as aluminium sulphate, starch, cationic polymers and the like. The Ra value for a normal grade base paper is well above 1.0 μm typically above 1.3 μm. In order to obtain a base paper with a Ra value below 1.0 μm such a normal grade base paper can be coated with a pigment. Any pigment can be used. Examples of pigments are calcium-carbonate, T1O2, BaSθ4, clay, such as kaolin, styrene- acr lic copolymer, Mg-Al-silicate, and the like or combinations thereof. The amount being between 0.5 and 35.0 g/m² more preferably between 0.5 and 20.0 g/m². This pigmented coating can be applied as a pigment slurry in water together with a suitable binders like styrene-butadiene latex, methyl methacrylate-butadiene latex, polyvinyl alcohol, modified starch, polyacrylate latex or combinations thereof, by any technique known in the art, like dip coating, roll coating, blade coating or bar coating. The pigment coated base paper may optionally be calendered. The surface roughness can be influenced by the kind of pigment used and by a combination of pigment and calendering. The base pigment coated paper substrate has preferably a surface roughness between 0.4 and 0.8 μm. If the surface roughness is further reduced by super calendaring to values below 0.4 μm the thickness and stiffness values will generally become below an acceptable level. The ink receiving multilayer of the present invention can be directly applied to the pigment coated base paper. In another embodiment, the pigment coated base paper having a pigmented top side and a back-side is provided on both sides with a polymer resin through high temperature co-extrusion giving a laminated pigment coated base paper. Typically temperatures in this (co-)extrusion are above 280 °C but below 350 °C. The preferred polymers used are poly olefins, particularly polyethylene. In a preferred embodiment the polymer resin of the top side comprises compounds such as an opacifying white pigment e.g. T1O2 (anatase or rutile), ZnO or ZnS, dyes, coloured pigments, including blueing agents, like e.g. ultramarine or cobalt blue, adhesion promoters, optical brighteners, antioxidant and the like to improve the whiteness of the laminated pigment coated base paper. By using other than white pigments a variety of colors of the laminated pigment coated base paper can be obtained. The total weight of the laminated pigment coated base paper is preferably between 80 and 350 g/m². The laminated pigment coated base paper shows a very good smoothness, which after applying the ink receiving layer of the present invention results in a recording medium with excellent gloss. Examples of the material of the plastic film are polyolefins such as polyethylene and polypropylene, vinyl copolymers such as polyvinyl acetate, polyvinyl chloride and polystyrene, polyamide such as 6,6-nylon and 6-nylon, polyesters such as polyethylene terephthalate, polyethylene-2 and 6- naphthalate and polycarbonate, and cellulose acetates such as cellulose triacetate and cellulose diacetate. The support may have a gelatin subbing layer to improve coatability of the support. The support may be subjected to a corona treatment in order to improve the adhesion between the support and the ink receiving layer. Also other techniques, like plasma treatment can be used to improve the adhesion. The swellable ink-receiving layer has a dry thickness from 1 to 50 micrometers, preferably from 5 to 25 and more preferably between 8 and 20 micrometers. If the thickness of said ink receiving layer is less than 1 micrometer, adequate absorption of the solvent will not be obtained. If, on the other hand, the thickness of said ink receiving layer exceeds 50 micrometers, no further increase in solvent absorptivity will be gained. The media of the present invention can be used in any printing application where photographic quality is required. Although the invention is described herein with particular reference to inkjet printing, it will be apparent to the skilled person that the high quality recording media of the present invention are not limited to inkjet recording media (viz. media suitable to be printed on using inkjet printers), but that it is within the scope of the present invention to provide recording media that are suitable for creating high quality images by using other techniques as well, such as Giclee printing, colour copying, screen printing, gravure, dye -sublimation, flexography, and the like. The media display an excellent light fastness, or dye stability, after exposure to (ambient) light. Light fastness may be assessed by the protocol set out in the examples herein below. Typically, the media of the present invention have more than 80% remaining density. Furthermore, the media of the present invention may have an excellent coloration behavior, the coloration of the media upon storage at typical storage conditions being minimal. The coloration (viz. the "yellowing" of the white parts of the media of the present invention upon aging) may be assessed using a protocol in which L, a*, b* values are measured by a spectrophotometer (e.g. a MINOLTA CM-1000R). The media of the present invention may have a ΔE (whiteness difference, expressed as b* values measured on a spectrophotometer, before and after aging) value after two weeks of storage at 50°C and 40% relative humidity of less than 5, preferably 2 or less. The present invention will be illustrated in detail by the following non-limiting examples. Unless stated otherwise, all ratios given are based on weight. Examples

A. Preparation of gelatin with covalent linked functional groups A-l: Synthesis of gelatin AO-I loaded with the anti-oxidant (AO) p-dihydroxybenzene 13.7 gram (119 mmol) N-hydroxysuccinimide (NHS) and 24.6 gram (119 mmol) dicyclohexyl-carbodiimide (DCC) were added to a stirred solution of 17.8 gram (115 mmol) 2,5-dihydroxybenzoic acid (DHBA) in 200 ml DMSO to obtain the NHS-DHBA ester. After filtration of the solution 17.5 g (60 mmol) lysine was added and the reaction mixture was heated to 50°C for 3 hours. Hereafter the solution was cooled to room temperature and 12.3 g (60 mmol) of DCC was added. After 12 hrs the solution was added over 5 minutes to a solution of 50 gram lime-bone gelatin in 500 ml DMSO at 55°C. After 3 hours the solution was precipitated in acetone, filtrated, washed 3 times on the filter with acetone and subsequently oven dried (at 30°C). The resulting modified gelatin AO-I had a degree of coupling of 61 mmol of the anti-oxidant per 100 gram gelatin (about 70 % of the amine group was modified).

A-2: Synthesis of gelatin UV-I with a UV absorber First the N-hydroxysuccinimide (NHS) ester of UN-5 (the chemical formulae of compounds UN-1 to UN-6 are given hereinbelow) was prepared by mixing of 4.07 g UN-5 in 120 ml DMSO with 1.38 g ΝHS and 2.45 g dicyclohexyl carbodiimide (DCC). After 12 hrs the solution was filtered and 1.75 g of lysine was added. After 3 hours at 50°C the solution was cooled to room temperature and 1.23 g of DCU was added. The complete solution was added to a solution of 5 g gelatin in 50 ml DMSO and stirred for 3 hours at 55°C. The resulting UN-gelatin was precipitated in 500 ml ethyl acetate, filtered and washed on the filter 3 times with acetone. The modified gelatin was oven dried at 30°C. The final gelatin had a load of 60 mmol UN-absorber /100 g gelatin as determined with UN-spectroscopy. A-3: Synthesis of gelatin OB-I with an optical brightener 65.9 grams of optical brightener OB-1 (the chemical formulae of compounds OB-1 and OB-2 are given hereinbelow) was dissolved into 1000 cc of a 10% gelatin solution of 55°C. After dissolving, the pH was adjusted to 5.2. Next, a solution containing 28 millimol carbamoylpyridinium salt was added. The mix was allowed to react for 3 hours at 55°C. The excess OB-1, and contaminants were removed by ultrafiltration. The resulting gelatin OB-I had a load of 24 mmol OB-1 per 100 mg gelatin, as determined by UV/NIS spectrometry. It is also possible to start from an optical brightener substituted with a carboxyl group. In that case the amine group on the triazine ring of optical brightener OB-1 is replaced by a carboxyl group. Such structures are described in for example EP-A-1 300 514. A skilled person is then able to perform a coupling along the lines of the methods described for coupling of the anti-oxidants and UN-absorbers described here above. The advantage of the described coupling to a free amine on the optical brightener molecule, is that this results in a secondary amine group in that position. The presence of such secondary amine groups increases the fluorescence intensity of the optical brightener. Substituting a carboxy group instead of the amine group will decrease fluorescence intensity.

B. Preparation of underlayer solution 'B' of the ink receiving layer. A 20 wt.% solution of a lime processed gelatin was prepared at pH 9. An aqueous solution of 10 wt % polyethylene oxide (PEO) having molecular weight of approximately 100 000 (from Sigma Aldrich chemicals, the Netherlands), was also prepared at pH 9. A homogeneous mixture (viz. without phase separation occurring), of gelatin and PEO having a weight ratio of 6:1 was made by adding 143 weight parts of said PEO solution and 429 weight parts of water into 428 weight parts of said gelatin solution at a temperature of 40°C. This mixture was agitated gently for about 30 minutes.

C. Preparation of underlayer solution 'C of the ink receiving layer. Underlayer solution 'C ' was prepared in the same way as underlayer-B, except that PEO was replaced by polyvinyl pyrollidone (PVP) having a molecular weight of 30 000 Daltons (ICN Biochemicals).

D. Preparation of the overlayer solution T)' of the ink receiving layer. A solution containing 50 weight parts of Gelita^® Imagel MA (dodecenyl-succinic modified acid treated gelatin from Stoess GmbH, Germany with a modification degree of 40%), 1 weight part of Zonyl^® FSN surfactant (a non-ionic fluoro-carbon type of surfactant) and 949 weight parts of water was prepared at 40°C. The pH of the solution was adjusted to 8.5 by adding NaOH.

E. Preparation of a UN-agent oil in water emulsion-'E' 120 Gram of UN absorbing agents (a mixture of UN-l/UN-2/ UN- 3/UN-4 = 2/1/1/1), 40 gram dibuthyl phtalate, and 20 gram of a 20% sorbitane monolaurate methanol solution were mixed in 100 ml of ethyl acetate at 65°C. The solution was dispersed in 500 ml of an aqueous solution containing 20% lime bone gelatin by weight using a homogeniser. After emulsification the solution was diluted to 1000 g by water. The size of dispersed droplets was determined by the disc centrifuge particle size measurement, and the mean diameter was 130 nm.

The underlayer(s) and overlayer solutions mentioned above were fed into a slide coating machine, commonly known in the photographic industry, and coated on a photographic grade paper having polyethylene laminated at both sides. The flow of the under- and overlayers were selected such that, after drying, a total solid content of the underlayer(s) (= gelatin + other water soluble polymer) between 8 to 25 g/m² was obtained and a total solid content of the overlayer between 0.5 and 5 g/m². After coating, the coated material was chilled at a temperature of ca. 12°C to set the gelatin and then dried with dry air at a maximum temperature of 40° C. These examples describe one way of applying the invention. An overview of the layer structures of these examples is given in table 1, below.

Example 1 — comparative example In the order recited, the following layers were coated on a laminated substrate: Underlayer 1: 50 cc/m2 of underlayer solution 'B' Underlayer 2: 100 cc/m² of a 1:1 mixture of underlayer solutions 'B' and 'C. Overlayer 1: 40 cc/m2 of overlayer solution 'D' This gave an inkjet recording material with good printing properties but having poor whiteness and dye stability with prolonged exposure to light.

Example 2 - comparative: The sample was prepared in the same way as example 1, except for underlayer 2: 40 weight parts of UN-agent oil in water emulsion Ε' was mixed with 480 weight parts of underlayer solution 'B' and 480 weight parts of underlayer solution 'C, in which 2.97 gram anti-oxidant 1,4-dihydroxybenzene was dissolved. Of the resulting mixture 100 cc/m² was coated. This material has better dye stability because of the presence of UN-absorbers and anti- oxidant.

Example 3 — comparative: The sample was prepared as in example 1, except for underlayer 2: In 1000 grams of a 1:1 mixture of underlayer solutions 'B' and 'C, 4.31 grams of UV-absorber UN-6 and 2.97 grams of the anti-oxidant 1,4- dihydroxy benzene was dissolved. Of the resulting mixture 100 cc/m2 was coated. This material had a somewhat better dye stability, probably because of the more effective dispersion of UN- absorber.

Example 4 - inventive: The sample was prepared as in example 1, except that underlayer 2 was split into 3 separate layers designated T, 'm' and 'u.'. Of the first separate layer 1', 19 cc/ m² is coated onto underlayer 1. The composition of this first separate layer T was the same as underlayer 2 in example 1. Of the second separate layer 'm', 28 cc/m² is coated onto layer T. The composition of this second separate layer 'm' is the same as underlayer 2 in example 1, except that the gelatin in underlayer solutions 'B' and 'C were replaced by gelatin A2, with covalent linked UN-absorber. Onto this second separate layer 'm' 53 cc/m² of a third separate layer 'u' was coated. The composition of this third separate layer 'u' was the same as underlayer 2 in example 1, except that the gelatin in underlayer solutions 'B' and 'C was replaced by gelatin Al, with covalent linked anti oxidant. This material showed a significant improvement in dye stability. The dye-stabilizers did not diffuse away and remained at its location and of the printed dyes.

Example 5 - inventive The sample was prepared as in example 4, except that in 1000 gram of underlayer 1, 13 gram of OB-2 was dissolved before coating. The sample showed a somewhat better whiteness.

Example 6 - inventive The sample was prepared as in example 1, except that underlayer 2 was split into 2 separate layers designated T and 'u'. Of the first separate layer T, 28 cc/m² was coated onto underlayer 1. The composition of this first separate layer T was the same as underlayer 2 in example 1 except that the gelatin in underlayer solutions 'B' and 'C were replaced by gelatin A2, with covalent linked UN-absorber. Onto this first separate layer T 87.5 cc/m² of a second separate layer 'u' is coated. The composition of this second separate layer 'u' was the same as underlayer 2 in example 1, except that the gelatin in underlayer solutions 'B' and 'C was replaced by gelatin Al, with covalent linked anti oxidant, and gelatin A3, with covalent linked optical brightener, in a ratio A1:A3 = 11:6. This sample had a better whiteness than any of the preceding experiments.

Table 1.

E. Evaluation of the printed image on the media The ink jet media prepared by the above mentioned formulation and said coating process, were printed with a standard image comprising black, cyan, magenta and yellow bars. The image contained also two pictures; including a portrait picture and a composition picture. The image was printed at a room conditions (23°C and 48% Relative Humidity (RH)) and the printed materials were kept at this condition for at least 1 hour to dry. A HP Deskjet ^® 995c was used to print the images by using the following settings: • Print quality : best • Selected Paper type: HP premium plus photo paper, glossy • Other parameters were according to the factory setting.

Definitions of the image evaluation 1. Light fastness Light fastness, or dye stability, was measured after exposing the printed samples to xenon light (85 000 lx) for 144 hours (Atlas Weather-O- Meter C I 35A, manufactured by Atlas (Illinois, U.S.A.)). The image density of the colors on the printed area is measured before and after the xenon irradiation by a reflection densitometer (X-Rite 310TR) and expressed as the remaining color-density percentage. The following classification has been defined: O: more than 80% remaining density Δ: 80-60% remaining density X: less than 60% remaining

Table 2.

As it can be seen from Table 2, the UN agent that is covalently coupled with gelatine is more effective for preventing dye fading than the UN agent which is not coupled with the gelatine, i.e. added as an oil-in-water emulsion or those dissolved in water. The whiteness of the ink jet media is also significantly improved by positioning the optical brightener which is coupled with the gelatine in a layer above the UN agent layer.

UV-1: UV-2:

UV-3: UV-4:

UV-5:

OB-1:

OB-2:

Claims

1. Recording medium comprising a support and an ink -receiving layer adhered to said support, where the ink receiving layer is a multilayer comprising a water-soluble polypeptide to which dye stabilizing functional groups are covalently linked.

2. Medium according to claim 1, wherein said polypeptide is a lime gelatin or acid gelatin or a modified gelatin or a recombinant gelatin.

3. Medium according claim 1, wherein said dye stabilizing functional groups are UV absorbing groups, an anti-oxidants, optical brighteners or combinations thereof.

4. Ink-jet recording medium according to any of the previous claims, wherein said dye stabilizing functional group is a UN absorbing group having an absorption of less than 400 nm.

5. Medium according to any of the previous claims wherein said dye stabilizing functional group is a UN absorbing group selected from the families of cinnamates, hydroxybenzophenones, benzotriazoles and aminobutadienes or a combination thereof.

6. Medium according to any of the previous claims in which the dye stabilizing functional group is a UN absorbing group and is applied in an amount of 0.1 to 5.0 g/m², more preferably from 0.2 to 1.0 g/m².

7. Medium according to any of the previous claims, in which said dye stabilizing functional group is an anti-oxidant group selected from the group of substituted phenolic and blocked phenolic compounds, phenolic thiane derivatives, substituted bisphenols, sterically hindred amines, hydrochinon and agents having molecular structures which are based upon a cresol type of molecule, a pyrogallol type, a cathechol type, or a 2,4-disulphonamidophenol type.

8. Medium according to any of the previous claims, in which said dye stabilizing functional group is an anti-oxidant group and is used in an amount of 0.05 to 2.5 g/m², more preferably from 0.1 to 1.0 g/m².

9. Medium according to any of the previous claims in which said dye stabilizing functional group is an optical brightener selected from the group comprising thiophenes, stilbenes, triazines, imidazolones, pyrazolines, triazoles and acetylenes.

10. Medium according to any of the previous claims wherein said dye stabilizing functional group is an optical brightener and is used in an amount of 0.01 to 5.0 g/m², more preferably from 0.02 to 1.0 g/m².

11. Medium according to any of the previous claims in which the ink receiving layer comprises at least one underlayer and a dye stabilizing layer coated on said underlayer(s) and an overlayer coated on said dye stabilizing layer wherein the dye stabilizing layer comprises dye stabilizing compounds covalently linked to a gelatin.

12. Medium according any of the previous claims where the ink receiving layer is a multilayer comprising at least one underlayer and at least one overlayer in which at least one overlayer comprises at least one type of modified gelatin selected from the group consisting of acetylated gelatin, phthalated gelatin, alkyl quaternary ammonium modified gelatin, succinated gelatin, alkylsuccinated gelatin, gelatin chemically modified with N- hydroxysuccinimide ester of fatty acid, and combinations thereof.

13. Medium according claim 12 wherein said modified gelatin comprises a C5-C2S alkyl group, a C5-C25 fatty acid group, or both; more preferably a C -Cιs alkyl group, a C₇-Cιs fatty acid group, or both.

14. Ink-jet recording medium according any of the previous claims in which the modified gelatin is used in an amount of 0.3 to 5.0 g/m², more preferably from 0.5 to 3.0 g/m².

15. Medium according to any one of the previous claims, wherein the support is selected from a paper, a base paper, a pigment coated base paper, a laminated pigment coated base paper, a laminated paper, a synthetic paper or a film support.

16. Medium according to any one of the previous claims, wherein the support has a surface roughness Ra smaller than 1.0 μm, preferably smaller than 0.8 μm.

17. Process for preparing an ink -jet recording medium comprising the steps of: providing a mixture of a water-soluble polypeptide, preferably an aqueous mixture, and providing one or more compounds having a dye- stabilization functional group, which is linked to a coupling group and subsequently adding said compound(s) to said mixture and reacting said coupling group with at least a portion of the amino groups in said polypeptide as to form a covalent bond between said polypeptide and said functional group, by which a solution of a dye-stabilization functionalized polypeptide is obtained, preparing at least one aqueous mixture for the overlayer, preparing at least one aqueous mixture for the underlayer(s), adding said solution of a functionalized polypeptide to one or more of the mixtures for the overlayer or the undeι ayer(s), - applying said mixtures consecutively or simultaneously to a substrate followed by drying upon which said ink -jet recording medium is obtained.

18. A method of forming a permanent, precise ink -jet image comprising the steps of: providing an ink -jet recording medium as defined in any of the claims 1- 16; and bringing ink -jet ink into contact with the medium in the pattern of a desired image.