WO2005032834A1

WO2005032834A1 - Recording medium

Info

Publication number: WO2005032834A1
Application number: PCT/NL2004/000691
Authority: WO
Inventors: Jacko Hessing; Akira Kase
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 ink absorption speed, good drying characteristics and a good image printing quality and good light fastness. According to the present invention an ink-jet recording medium is provided, comprising a support to which at least an underlayer and an overlayer is supplied in which the overlayer contains at least one type of modified gelatin and one of the layers comprises a hydrophobic reducing agent. 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 a good image printing quality, excellent storage stability, good light fastness 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. There are in general two approaches for producing ink -jet recording media with photographic quality and good drying properties. One known approach is to provide a substrate with a porous layer, which can act as the ink-receiving layer. However, this known technique may give problems as to the gloss of the paper. In a specific embodiment of the known technique of substrates provided with a porous layer, there is provided on top of the porous layer a gloss-enhancing layer. In this microporous type, the microporous film has as the primary function to absorb the ink solvent. The typical microporous film suitable for this purpose is described inter alia in - US-A-4 833 172, US-A-4 861 644, and US-A-5 326 391. Another approach for producing ink -jet recording media with, photographic quality and good drying properties is the so called "non- microporous film type", also known as "swellable type", as proposed in several patent publications such as EP-A-806 299 and JP-A-22 76 670. For this type of ink -jet recording medium, at least one ink receptive layer is coated on a support such as a paper or a transparent film. The ink receptive layer "typically contains various proportions of water-soluble polymers and fillers. The proportions of these components affect the properties of the coatings, in particular ink absorption properties and the gloss quality appearance of the ink -jet media. One of the important properties of an ink -jet receptive coating formulation is the liquid absorptivity. The majority, if not all, of the ink solvent has to be absorbed by the coating layer itself. Only when paper or cloth or cellulose is used as a support, some part of the solvent may be absorbed by the support. It is thus clear that both the water-soluble polymer and th.e filler should have a significant ability to absorb the ink solvent. As a water-soluble polymer, polyvinyl alcohol is disclosed in for example US-A-2002/142141 and in EP-A-875 393. 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 for the absorption of ink solvents. The gelatin is said to improve smudge resistance, increase the definition quality, and give high gloss, fast water absorbing properties, easy to achieve high water resistance and good dye fading resistance. Although the use of gelatin in ink -jet media provides certain advantages, problems like curl and brittleness of the coating and problems like beading, bleed and matte appearance at high densities may still occur. Various countermeasures have been suggested to overcome these - problems., In WO-A-00/53406 the use of at least one plasticiser selected from the group comprising 2-pyrrolidone and its derivatives, or urea and its derivatives is described to overcome the curl and brittleness. US-A-6 183 844 describes the use of highly filled multilayers to improve bleed and wet smear resistance. EP-A-0 742 109 describes the use of a combination of anionic and cationic fluorine containing surfactants in order to improve dot reproduction especially for graphic art applications. EP-A-1 080 936 describes the use of a non-ionic surfactant giving a lower surface tension in the layer of an ink receptive multilayer farthest from the support and a second non-ionic surfactant giving a higher surface tension in the layer nearer to the support material. Improved gloss and bleed is claimed. Apart from the above-mentioned problems, a major further concern for ink-jet prints is the light stability and coloration upon aging. GB-A-2 088 777 describes the use of anti-oxidants to increase the light stability. WO-A-02/55617 describes the use of special hydrophilic light stabilizers for ink -jet application. Although some improvements can be obtained by the described methods, there remains a need for low cost ink -jet material with good image printing quality, good drying properties, improved curl and brittleness, having at the same time good behavior on bleed, beading and matte appearance at high density parts, while at the same time the image has good light fastness, and coloration properties viz. after printing the formed image will not fade under the various storage conditions. 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 drying properties, said recording medium more in particular being suited to produce images of photographic quality. It is another object of the present invention to provide a recording medium with reduced brittleness at low humidities and excellent curl behaviour. It is a further object of this invention, to provide a recording medium, which gives no beading and has no matte appearance at high densities and has good bleeding properties. It is still a further object of this invention to provide a recording medium in which the image formed after printing shows no fading and no coloration, viz. a medium having a good lightfastness. It has been found that these objectives can be met by providing a recording medium comprising a multilayer structure, wherein a hydrophobic reducing agent is present in at least one of the layers of said multilayer structure. 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 an underlayer and an overlayer which underlayer and overlayer both comprise one or more (sub-)layers in which the overlayer comprises at least one type of modified gelatin and in which at least one of the layers comprises a hydrophobic reducing agent. This invention is also related to the manufacturing of such a recording medium and the use of this medium. Reducing agents are employed in ink -jet recording media to protect the ink-jet inks from fading. Without wishing to be bound by theory, it is assumed that the improvements obtained according to the present invention may be due to the fact that on the one hand coloration is improved because the hydrophobic reducing substance is protected better towards oxidation by its hydrophobic nature. In particular the influence of moisture from the environment is much less, so the media of the present invention can be stored for a longer time without adverse effects on their quality. On the other hand the effectiveness of the reducing agent for aging under light conditions is believed to be improved because hydrophobic reducing agents can be localized in or close to the layers which are to receive the dyes which should be protected for aging. In addition hydrophobic reducing agents were found to suffer much less from diffusion to other layers when compared with hydrophilic reducing agents. In the conventional media for in -jet application comprising at least one ink-receiving layer based on a water soluble polymer, such as gelatin, PVA, 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 problems like bleed, beading, finger print smearing and matte appearance at high densities. Another problem encountered is that the dyes used in the ink tend to fade over time when applied on the ink -jet-printing medium. We have now found surprisingly that these negative properties can be improved very much by using a medium on which the ink-receiving layer is a multilayer, at least comprising one underlayer and one overlayer. In this type of ink-receiving layer, the underlayer especially determines the physical and ink-receiving properties, while the overlayer determines the surface properties like beading and gloss. The overlayer of this invention comprises a modified gelatin, and may further comprise water insoluble particles inter alia to regulate the slip behavior and optionally one or more water-soluble polymers, surfactants and other additives to optimize the surface properties. The stability of the dyes of the image formed after ink -jet printing is determined by the kind of dye and the properties of both the overlayers and the underla ers. Especially the presence - of hydrophobic reducing agents in one of the layers is effective in the stabilization of the dye as has been found in this invention. 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 2 to 17. The term "modified gelatin" as used herein, refers to gelatin compounds in which at least part of the NH₂ groups is chemically modified. 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 another 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 C5-C25- lkyl group), a fatty acid group (more preferably Cs- C₂5-fatty acid group), or both. Even more preferably the gelatins comprise a C₇- Ci8-alkyl group, a C7-Cτ.8-fatty acid group, or both. Especially preferred gelatins of this type are succinic 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 dodecenylsuccinic acid modified gelatin, in which at least 30% of the NH₂ groups of the gelatin have been modified with said dodecenylsuccinic acid. Another method for obtaining modified gelatin is described in EP-A-0 576 911, where said gelatin is formed from gelatin containing pendant amine groups and pendant carboxylic groups wherein at least one amine group - of said gelatin is modified to form an amide of the formula -NHCOR. The process typically involves reaction of an amine group with an activated carboxyl, i.e. a reaction product of a carboxyl activating agent and carboxylic acid, i.e., RCOOH wherein R represents substituted or unsubstituted alkyl of 1-10 carbons, substituted or unsubstituted aryl of 6-14 carbons, or substituted or unsubstituted aryl alkyl of 7-20 carbons. Other suitable methods are described 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) wherein hydrophobic groups are attached to gelatin molecules by reacting gelatin with respectively N-Hydroxysuccinimide ester of caprylic acid and N- Hydroxysuccinimide ester of various fatty acids (C4-C16). Other 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 phthalated gelatin and acetylated gelatins are also suitable to be used in this invention. The modified gelatin can be used alone or in combination with another water-soluble polymer. Examples of these polymers include: polyvinyl alcohol- (PVA-)based polymers, such as fully hydrolysed or partially hydrolysed polyvinyl alcohol, carboxylated polyvinyl alcohol, copolymers and terpolymers of PVA with other polymers, watersoluble cellulose derivatives such as 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, pig bone or cow bone, polyethylene oxide, poly aery lamide, and the like. The modified gelatin is applied in the overlayer preferably in an amount ranging from 0.3 to 5 g/m² and 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 fluorosurfactant in the amount between 2.5 mg/m² and 250 mg/m². It was found that 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 of fluorocarbon and hydrocarbon as the hydrophobic part. Suitable fluorosurfactants may be anionic, non- ionic or cationic. Examples of suitable fluorosurfactants are: fluoro C2-G20 alkylcarboxylic acids and salts thereof, disodium N-perfluorooctanesulfonyl glutamate, sodium 3-(fluoro-C6-Cii alkyloxy)-l-C3-C4 alkyl sulfonates, sodium 3-(omega -fluoro-CG-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, perfiuorooctane sulfonic acid diethanolamide, Li, K and Na perfluoro C -C].2 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 fCH2CH2SCH2CH2CO Li or R_fCH2CH2θ(CH2CH₂O) H wherein Rf = 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 (fluoroalkyl)-2-[2-N,N,N- ^' trialkylammonium) alkyl amino] butanedioate, perfluoro CG-CIO alkylsulfonamide propyl sulfonyl glycinates, bis-(N-perfluorooctylsulfonyl-N- ethanolaminoethyl)phosphonate, mono-perfluoro Cβ-CiG 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 RfCH₂CH SCH2CH₂CO2Li or _fCH2CH₂O(CH2CH2θ)χ 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 ink -jet media 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)acrylate, a glycidyl(meth)acrylate, a (rneth)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.I. Publication Nos. 49- 106821/1974 and 57-14835/1982. These matting agents may be used alone or in combination. In another embodiment of this invention the beneficial effects of the modified gelatin and the fluorosurfactant is generated by applying these compounds in a separate overlayer coating, 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 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, UV absorbers, anti-oxidants, light- stabilizing agents, dispersing agents, anti-foaming agents, levelling 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 % based on the solid content of the overlayer. The underlayer is preferably a multi layer preferably comprising gelatin and one or more hydrophilic polymers and optionally additives to adjust the physical properties. This swellable underlayer determines mainly the physical properties like water uptake, drying speed, brittleness, curl and image stability. 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 between the support and the underlayer an adhesion promoting layer is applied 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. 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), recombinant 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. Water soluble polymers suitable to be mixed with the (modified) ^" gelatin include polyvinyl alcohol- (PVA-)based polymers, such as fully hydrolysed or partially hydrolysed polyvinyl alcohol (PVA), carboxylated polyvinyl alcohol, copolymers and terpolymers of PVA with other polymers, watersoluble cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, casein, gum arabic, polyacrylic acid and its copolymers or terpolymers, polymethylacrylic 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 (PVP), polyethylene oxide, poly aery lamide, 2-pyrrolidone and its derivatives such as N (2-hydroxyethyI)- 2-pyrrolidone and N-cyclohexyl-2-pyrrolidone, urea and its derivatives such as imidazolidinyl urea, diazolidinyl urea, 2hydroxyethylethylene urea, and ethylene urea. Water soluble (co) polymers can have a limited compatibility with gelatin. Such polymers include fully hydrolyzed or partially hydrolyzed polyvinyl alcohol, hydroxyl-ethyl-cellulose, methylcellulose, hydroxyl-propyl 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. By applying the overcoating of the invention on such an underlayer, it will improve the appearance significantly. It is however better to use the inventive overcoating on an underlayer in which no phase separation between the gelatin and the water-soluble polymer occurs. 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. PEO (polyethylene oxide) is one of the water-soluble polymers showing a bad compatibility with gelatin. 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 acid treated gelatins having an iso-electric-point (IEP) of between 6.0 and 11 give a homogeneous solution with 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 has IEP value of between 4 and 6.0, 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 6.0. In addition to the above mentioned pH adjustment, we have now found, that it is not only important to have a homogeneous solution, but it is also beneficial to have a molecular weight (MW) 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 . The various underlayers may have compositions, which can be different for each layer. So each layer of the underlayer may comprise different kinds of gelatins and different kinds of water-soluble polymers or combinations of water-soluble polymers. So in one embodiment it is beneficial to use PEO in the underlayer nearest to the overlayer, while in the underlayers nearer to the support material no PEO is present. In another embodiment PEO is present in all the layers, but the gelatin/PEO ratio increases when going from the top underlayer (nearest to the overlayer) in which the ratio varies from 1/1 to 8/1 to the underlayer nearest to the support in which the ratio varies from to 1/1 to 12/1. The gelatin-water soluble polymer solutions of the underlayer, which ^" are supplied to the substrate have a gelatin concentration of in general between 5 and 20 wt.%. Embodiments using PEO are described; similar embodiments can be described for mixtures of gelatin and other water soluble polymers having a limited compatibility with each other. It has been found by the present inventors that one may substitute the PEO with other water soluble polymers mentioned above such as PVP or PVA or a mixture between two or more water soluble polymers such as PEO and PVP. 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 PVA-based polymers. In general a large variety of PVA-based polymers can be used, but the preferred PVA-based polymers are those which have been modified to give a good miscibility with aqueous gelatin solutions. These modifications are such, that in the PVA-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 PVA-based polymer. A modified PVA- based polymer giving very good results is a poly(vinyl alcohol)-co-poly(n-vinyl formamide) copolymer (PVA-NVF). Very suitable PVA-NVF 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 3 are independently H, 3-propionic acid or CI-C_G alkyl ester thereof, or is 2-methyl-3-propionic acid or CI-CG alkyl ester thereof; and R2 and R4 are independently H or CI-CG 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. In order to stabilize the image formed after applying the ink-jet ink onto the ink -jet recording medium the ink-receiving layers of said medium comprising one or more overlayers and one or more underlayers should comprise at least in one of said layers one or more hydrophobic reducing agents. In the prior art (WO-A-02/055617) reducing agents are described, which are hydrophilic rather than hydrophobic. However these agents tend to diffuse after coating over the various applied layers reducing the effectiveness and giving rise to a bad surface appearance. Another problem is, that these hydrophilic reducing agents will decompose upon storage in humid conditions, giving a yellow coloration of the recording medium. Although these hydrophilic reducing agents can be used in the present invention it is better to use hydrophobic reducing agents, as these show the negative effects of the hydrophilic reducing agents to a much lesser extent. There are various ways in which the hydrophobic reducing agents can be added. In one embodiment the hydrophobic reducing agent is dispersed in a hydrophilic solvent by adding the compounds as solutions in low boiling organic solvents like for example ethylacetate, butylacetate or n-butanol under vigorous stirring. In another embodiment the hydrophobic reducing agent is added as - such to a solution of a hydrophilic polymer in water to give a dispersion. The hydrophilic polymer is selected from the group of gelatin, polyvinyl alcohol (PVA), polyvinylpyrollidone (PVP), carboxymethylcellulose (CMC), hydroxyethylcellulose (HEC) and the like. One of the most suitable hydrophilic polymers is gelatin. The gelatin can be any of modified or non-modified gelatins. 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. After the hydrophobic reducing agent is added to the solution of the hydrophilic polymer in water, a dispersion is made using one of the techniques known to those in the art. These methods include methods using a high speed rotating disk, rotor stator methods, methods using any conventional colloid mill, a method using a homogeniser and the like. It is normal practice to add one or more surfactants or stabilisers before or after the dispersion process. Surfactants suitable for the practice of this invention are for example: alkyl aryl sulfonates, potassium salts of alkyl naphthalene sulfonic acids, sodium dialkyl naphthalene sulfonate, sodium alkyl naphthalene sulfonate, sodium dodecylsulfate, sodium dodecylbenzenesulphonate, tetrasodium N- (l,2-dicarboxyethyl)-N- octyldecylsulfosuccinamate and the like. The quantity of surfactant used most general equal to about 5% of the hydrophobic reducing agent amount. In another embodiment the hydrophobic reducing agent is added as an oil-in-water emulsion. The oil-in-water emulsion is made by mixing an aqueous solution of hydrophilic polymer material in the hydrophilic phase with a hydrophobic phase comprising the hydrophobic reducing agent and a high boiling organic solvent. Mixing can be executed by stirring, by high-pressure homogenisation, by treatment with ultrasonic frequencies, or the like. The high-boiling organic solvents of this invention have a boiling point of not lower than 175°C at normal pressure. For example, trialkyl phosphates and triaryl ^' phosphates such as trihexyl, trioctyl, tridecyl, tris (butoxyethyl), tris (haloalkyl), trixylenyl and tricresyl phosphate, can be used for preparing photographic emulsions. Also phthalate esters, citric esters, benzoic esters, fatty acid esters and fatty acid amides, as well as hydrocarbons such as n- decane or n-dodecane can be used. Organic solvents having a boiling point of not lower than about 30°C, preferably not lower than about 50°C, but not higher than about 160°C can be used as co-solvents. Examples of the co- solvents include ethyl acetate, butyl acetate, ethyl propionate, methyl ethylketone, cyclohexanone, 2-ethoxyethyl acetate, dimethylformamide and the like. The hydrophilic polymer can be selected from the group of gelatin, Polyvin lalcohol (PVA), PMA (polymethylacrylate), PVP (polyvinylpyrollidone), carboxymethylcellulose (CMC), Hydroxyethylcellulose (HEC) and the like. The most suitable hydrophilic polymer is gelatin. The gelatin can be any of modified or non-modified gelatins. 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. Surfactants, such as sodium dodecylbenzenesulphonate, can be added as emulsification aid and as emulsion stabilisation agent. The average particle size of the oil droplets of the oil-in- water emulsion is preferably below 500 nm and more preferably below 300 nm in order to avoid light scattering. The under limit of the particle size is mainly determined by the used recipe and the mechanical forces used to make the oil- in-water emulsion. The average particle size is mostly over 50 nm and more in general over 100 nm. The hydrophobic reducing agents of this invention are preferably selected from substituted phenol and blocked phenol compounds, phenol thiane derivatives, substituted bisphenols, alkylated hydroquinone compounds 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. Such stabilizing addenda can be used alone or in combination. The best results are obtained with those reducing agents or anti-oxidants, which have poor water solubility. The solubility of particularly advantageous hydrophobic reducing compounds in water at 20°C and standard pressure should be lower than 1 g/1 and most preferably below 0.1 g/1. The hydrophobic reducing agent can be added in any of the layers of the ink-receiving layer, but most preferably it is added in the underlayer and more preferably in that layer of the underlayer which is nearest to the overlayer in case the underlayer is a multilayer. The amount of hydrophobic reducing agent generally is between 0.01 g/m² until 3 g/m² and preferably between 0.05 g/m² and 1.0 g/m². The underlayer may further contain the following ingredients in order to improve the ink-receiving layer properties with respect to ink receptivity and strength: - One or more plasticizers, such as ethylene glycol, diethylene glycol, prop lene 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, polymethacrylate, polymethyl-methacrylate, elastomers, ethylene -vinyl acetate copolymers, polyesters, polyester -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 -dimethylphenethylamine hydrochloride, 2- fluoroethylaminehydrochloride, 2-fluoro- 1-methyl pyridinium-toluene sulfonate, 4-fluorophenethylamine hydrochloride, fluorophenylhydrazine hydrochloride, l-(2-fluorophenyl) piperazine monohydrochloride, 1 -fluoro pyridinium trifluoromethane sulfonate. - One ore 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; • UV absorbing agents; • Light stabilizing agents • Brightening 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 or mixture of hydrophilic polymers used in a certain formulation 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- invention also known as hardening agents. Examples of the hardener include aldehyde compounds such as formaldehyde and glutar aldehyde, 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 PVA, for example, it is preferable to choose a cross-linking agent selected from borax, glyoxal, dicarbox lic acids and the like. The process for producing a recording medium can be described by the following the steps. preparation of a dispersion or an oil in water emulsion comprising a hydrophobic reducing agent; - preparation of at least one aqueous mixture comprising at least a modified gelatin for the overlayer; - preparation of one or more aqueous mixtures for one or more underlayers; mixing said dispersion or said oil in water emulsion comprising a hydrophobic reducing agent with at least one of the mixtures for the overlayer(s) or the underlayer(s). The resulting formulation for the overlayer(s) and underlayer or underlayers 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, BaSO4, 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, poly aery lamide, 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, TiO₂, BaSO₄, clay, such as kaolin, styrene- acrylic 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. Tiθ2 (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 polyolefin's 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 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 medium 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 of the present invention may have an excellent lightfastness, viz. dye stability during the display or storage in the presence of (ambient) light. Lightfastness may be quantified using known techniques, for example by using an Atlas Wether-O-Meter C I 35A, (manufactured by Atlas (Illinois, U.S.A.) and exposing the image during 144 h using a xenon light at 85,000 lx. The image density of the color on the printed area can be measured before and after the xenon exposure e.g. by a reflection densitometer (X-Rite 310TR). It can be expressed as the residual dye percentage. The media of the present invention may have a residual percentage (measured using a Wether- O-Meter C I 35A and the X-Rite 310TR under the conditions set out above) as high as 80% or more. 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 the overlayer solution-A 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 (modification grade 40%)), 1 weight part of Zonyl^® FSN surfactant (a non-ionic fluoro-carbon type 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. B. Preparation of the gelatin hydrophilic polymer solution-B 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. no phase separation occurred), 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 the gelatin hydrophilic polymer solution-C Polymer solution-C was prepared in the same way as polymer solution-B. A mixture of gelatin and polyvinyl pyrollidone (PVP) was prepared in the weight ratio of 6 to 1 wherein PVP has a molecular weight of about 30,000 Daltons (ICN Biochemicals).

D. Preparation of an oil in water emulsion-D comprising a hydrophobic reducing agent 45 g of hydrophobic reducing agent (compound- 1; the chemical formulae of compounds 1 to 6 are given below), 75 g of compound- 2, 120 g of compound-3, and 18 g of compound-4 were mixed in 50 ml ethyl acetate at 65°C. The solution was dispersed in 500 ml of an aqueous solution containing 20% lime bone gelatin by weight by a homogeniser. After emulsification the solution was diluted up to 1000 g by water. The size of dispersed droplets was examined by the disc centrifuge particle size measurement, and the mean diameter was 180 nm.

E. Preparation of an oil in water emulsion-E comprising a hydrophobic reducing agent 45 g of the hydrophobic reducing agent (compound- 1), 50 g of compound-5, and 18 g of compound-4 were mixed in 80 ml of ethyl acetate at 65°C. The solution was dispersed in 500 ml of an aqueous solution containing 20% lime processed gelatin by weight by a homogeniser. After emulsification the solution was diluted up to 1000 g by water. The size of dispersed droplets was examined by the disc centrifuge particle size measurement, and the mean diameter was 200 nm.

F. Preparation of the aqueous solution F of a hydrophilic reducing agent- 50 g of hydroquinone (compound-6) was dissolved at room temperature in 950 g of water containing 10 % lime processed gelatin.

G. Schematic drawing and definition of the layer structure: The ink receiving layer structure consisted of two underlayers and one overlayer as shown in the scheme below.

Overlayer Underlayer 2 Underlayer 1 Laminated Substrate Examples

The main body of the overlayer consists of overlayer solution-A. The main body of underlayer 2 was prepared by mixing same weight parts of polymer solution-B and polymer solution-C. The main body of underlayer 1 consists of polymer solution-C. The 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 typical flow of the layers were 40 cc/m² for the overlayer, 100 cc/m² for underlayer 2, and 50 cc/m² for underlayer 1. After coating, the solution 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. Inventive example #1 20 weight parts of oil in water emulsion-D was mixed with 400 weight parts of overlayer solution-A and coated at flow of 40 cc/m². Under layers were coated as described above.

Inventive example #2 20 weight parts of oil in water emulsion-D was mixed with 500 weight parts of solution-B and 500 weight parts of solution-C. The mixture was coated at flow of 100 cc/m². The other layers were coated as described above. Inventive example #3 ,20 weight parts of oil in water emulsion-D was mixed with 1000 weight parts of solution-C and coated at flow of 100 cc/m². The other layers were coated as described above.

Inventive example #4 20 weight parts of oil in water emulsion-E was mixed with 500 weight parts of solution-B and 500 weight parts of solution-C. The mixture was coated at flow of 100 cc/m². The other layers were coated as described above.

Comparative example #5 Only the main bodies of each layer were coated and the flow of the layers were the same as described above. Comparative example #6 6 weight parts of hydroquinone solution-F was mixed with 400 weight parts of overlayer solution-A and coated at flow of 40 cc/m². Underlayers were coated as described above. Comparative example #7 6 weight parts of hydroquinone solution-F was mixed with 500 weight parts of solution-B and 500 weight parts of solution-C. The mixture was coated at flow of 100 cc/m². The other layers were coated as described above. Comparative example #8 6 weight parts of hydroquinone solution-F was mixed with 1000 weight parts of solution-C and coated at flow of 100 cc/m². The other layers were coated as described above. I. 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)). 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. The quality of the printed images were then analysed visually by analysing the beading behaviour, the glossiness of especially the black area, the dryness of especially the black area, and the bleeding behaviour after some period of time.

J. Definitions of the image evaluation 1. Light fastness Light fastness is a dye stability during the display or storage at light condition. In order to evaluate this behaviour a sample was exposed for 144 hrs using a xenon light (85,000 lx) in an Atlas Wether-O-Meter C I 35A, (manufactured by Atlas (Illinois, U.S.A.)). The image density of the color on the printed area is measured before and after the xenon exposure and was measured by a reflection densitometer (X-Rite 310TR) and evaluated as the dye residual percentage. The following classification has been defined: O: 80% or more residual percentage Δ: 80-60% residual density X: less than 60% of residual density 2. Beading behaviour As set out hereinabove, beading is defined as the phenomenon that large ink dots that become visible on the printed image. The following classification has been defined: O: no beading is observed

Δ: some small spots which is not very visible and/or beading that can be solved by selecting another printer settings. X: Clearly visible 3. Glossiness after printing. The glossiness of the image directly after printing and after two days were analysed by observing the reflection of light on the high density area of the print (e.g. black colour). The more reflection was observed, the glossier the printed image. The following classification was defined for judging the Glossiness:

O: Still glossy after 2 days without any defects

Δ: Gloss after printing, but after 2 days some 'matte" spots was observed.

X: Matte appearance after printing, or a lot of "matte" spots after 2 days. 4. Whiteness Whiteness was judged after aging the samples for two weeks at a condition of 50°C and 40%RH. For determining the whiteness difference the parameter ΔE was measured, expressed as b* values, before and after aging.

The following classification was defined for judging the whiteness: O: ΔE<2

Δ: 2<ΔE<5

X: ΔE>5.

Results

Compound-1: Compound-2:

Compound-3: Compound-4:

Compound-5 Compound- 6

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 an underlayer and an overlayer which underlayer and overlayer both comprise one or more (sub-)layers in which said overlayer comprises at least one type of modified gelatin, i.e. a gelatin compound in which at least part of the NH2 groups is chemically modified, and in which at least one of the layers comprises a hydrophobic reducing agent.

2. Medium according claim 1, wherein the hydrophobic reducing agent is selected from the group of substituted phenolic and blocked phenolic compounds, phenolic thiane derivatives, substituted bisphenols, alkylated hydrochinon compounds 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.

3. Medium according to any of the previous claims, wherein the hydrophobic reducing agent is used in an amount between 0.01 and 3.0 g/m².

4. Medium according to any of the previous claims, wherein the hydrophobic reducing compound is added as a dispersion in a hydrophilic solution.

5. Medium according to any of the previous claims, wherein the hydrophobic reducing agent is added as an oil in water emulsion.

6. Medium according to claim 5 in which the oil in water emulsions comprises oil droplets having an average size of from 50 to 500 nm and more preferably from 50 to 300 nm.

7. Medium according to any of the previous claims in which said oil in water emulsion or said dispersion is present in at least one of the underlayers.

8. Medium according to claim 7 in which said oil in water emulsion or ^'said dispersion is present in the layer o if the underlayers that is nearest to the overlayer.

9. Medium according to any of the previous claims, wherein said modified gelatin is selected from the group consisting of acetylated gelatin, phthalated gelatin, alkyl quaternary ammonium nxodified gelatin, succinated gelatin, alkylsuccinated gelatin, gelatin chemically modified with N- hydroxysuccinimide ester of fatty acid, and combinations thereof.

10. Medium according to claim 9, wherein said modified gelatin comprises a C5-C25 alkyl group, a C5-C25 fatty acid group, or both; more preferably a C7- Ci₈ alkyl group, a C7-C18 fatty acid group, or both.

11. Medium according to any of the previous claims, wherein 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.

12. Medium according to any of the previous claims, in which the overlayer comprises further at least one fluoro -surfactant, preferably a fluoro-surfactant selected from the group of Li, K and Na- N-perfluoro C4-C13 alkane sulfonyl — N- alkyl glycine, 1,4-bis (fluoroalkyl)-2- [2 -N,N,N- trialkylammonium) alkyl amino] butanedioate, and fluorosurfactants having the chemical structure of R_fCH2CH₂SCH2CH₂C02Li or RfCH2CH2θ(CH₂CH₂O)χ H wherein R_f =

13. Medium according to claim 12, wherein the amount of fluoro-surfactant is from 2.5 to 25,0 mg/m². 14. Medium according to any of the previous claims in which the underlayer(s) further comprise gelatin, a modified gelatin or mixtures of modified and non-modified gelatin and a hydrophilic polymer or a mixture of hydrophilic polymers. 15. Medium according to any one off 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. Mediu 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 producing a recording medium, comprising the steps of: preparation of a dispersion or an oil in water emulsion comprising a hydrophobic reducing agent. - preparation of at least one aqueous mixture comprising at least a modified gelatin for the overlayer; - preparation of one or more aqueous mixtures for one or more underlayers; - mixing said dispersion or said oil in water emulsion with at least one of said mixtures; and - coating said mixtures consecutively or simultaneously on a support, followed by drying the coated support. 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 to 16; and - bringing ink-jet ink into contact with the medium in the pattern of a desired image.