WO2005072970A1

WO2005072970A1 - Recording medium

Info

Publication number: WO2005072970A1
Application number: PCT/NL2005/000073
Authority: WO
Inventors: Jacko Hessing; Huibert Albertus Van Boxtel; Sebastianus Gerardus Johannes Maria Kluijtmans; Yoichiro Kamiyama
Original assignee: Fuji Photo Film B.V.
Priority date: 2004-02-02
Filing date: 2005-02-02
Publication date: 2005-08-11

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, in particular an improved lightfastness. According to the invention there is provided an inkjet recording medium comprising a support and an ink-receiving layer adhered to said support, wherein the ink-receiving layer is a multilayer comprising a top layer and two or more intermediate layers between said support and said top layer, wherein at least two of said intermediate layers comprise a mixture of at least one PVA-based polymer and at least one water soluble polymer. The invention further relates to processes for preparing these media, as well as to using these media.

Description

Title: Recording medium

Field of 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 an improved lightfastness, 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 Ughtfastness, υiz. the printed images must not fade over longer periods of time. In order to improve the lightfastness of inkjet media, several approaches have been suggested in the prior art. JP-A-4 201 594, for instance, suggests to include hyperfine powder of specific transitions metal oxides into one or more layers and GB-A-2 147 003, for instance, suggests to combine metal salts with cationic polymeric substances to improve lightfastness of the produced images. Furthermore, JP-A-2002/220 559 and EP-A-0 869 010 describe a specific copolymer, which is to be included in one or more of the layers of the inkjet media, to improve lightfastness. JP-A-2000/280 601 discloses inkjet recording media wherein the lightfastness is improved by incorporating a UN absorbent in a protective layer of the media. WO-A-03/054029 describes poly(vinyl alcohol)-co-poly(n-vinyl formamide) copolymers (PNA-ΝVF) for use in inkjet recording media. The inkjet recording media of this document are said to have improved image permanence against the harmful effects of light and/or atmospheric pollutants. Another important aspect of recording materials is their gloss. When the lightfastness is to some extend improved, it still remains a problem to maintain the gloss on an acceptable level, while at the same time good drying properties together with acceptable whiteness, good image printing quality, good curl and brittleness properties are maintained. Also at the same time the recording materials should have good behaviour on bleed, beading and matte appearance, in particular at the high density parts of the recording materials. Further the materials should be available at low cost. Thus there remains a need for ink-jet materials having good lightfastness and good gloss keeping at the same time good physical properties as mentioned above. It is towards fulfilling these needs that the present invention is directed. Summary of the invention The object of the present invention is to provide a recording medium having good overall properties, said recording medium more in particular being suited to produce images of photographic quality, wherein said medium has an improved lightfastness. It is a further object of this invention to provide a recording medium where the medium has an improved light fastness and a good gloss. At the same time it is desirable that the media of the present invention maintain other favourable properties with respect to good drying properties, acceptable whiteness, good image printing quality, good curl and brittleness, having at the same time good behaviour on bleed, beading and matte appearance at high density parts. It was 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 top layer and two or more intermediate layers between said support and said top layer, where at least two of said intermediate layers comprise a mixture of at least one poly vinyl alcohol (PVA)-based polymer and at least one water soluble polymer, wherein the ratio of said PVA-based polymer/water soluble polymer in the intermediate layer closer to said top layer is higher than the ratio of PVA-based polymer/water soluble polymer in the intermediate layer closer to said support.

Detailed description The invention is directed to a recording medium comprising a support and an ink-receiving layer adhered to said support, wherein the ink- receiving layer is a multilayer comprising a top layer and two or more intermediate layers between said support and said top layer, wherein at least two of said intermediate layers comprise a mixture of at least one poly vinyl alcohol (PVA)-based polymer and at least one water soluble polymer. Through the use of intermediate layers comprising a PVA-based polymer the permanence of the images upon storage is positively influenced. GB-A-2 380 695 describes the combination of a styrene -aery late copolymer, a gelatin and a vinyl alcohol polymer to achieve a fast drying inkjet sheet. According to the present invention the use of a PVA-based polymer in combination with a water soluble polymer is sufficient to create a printable sheet with outstanding properties. In general a large variety of PVA-based polymers can be used, such as fully hydrolysed or partially hydrolysed PVA, carboxylated PVA, acetoacetylated PVA, quaternary ammonium modified PVA, copolymers and terpolymers of PVA with other polymers, or combinations thereof, but the preferred PVA-based polymers are those which have been modified to give a good miscibility with water and water soluble polymers. These modifications are such, that in the PVA 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. A PVA- based polymer giving 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:

(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 c y is between about 3 and about 20 mole percent; Ri, and R₃ are independently H, 3-propionic acid or Ci-Cβ alkyl ester thereof, or is 2-methyl-3-propionic acid or Ci-Cβ alkyl ester thereof; and R2 and R are independently H or Ci-Cβ alkyl. The present inventors have found, that it is beneficial for especially light fastness to provide a medium with at least two intermediate layers comprising a PVA based polymer together with a water soluble polymer, wherein the PVA/water soluble polymer ratio of the intermediate layer closer to the support is lower than the PVA/water soluble polymer ratio of the intermediate layer further away from said support, or alternatively described as the condition that the ratio of said PVA-based polymer/water soluble polymer in the intermediate layer closer to the top layer is higher than the ratio of PVA-based polymer/water soluble polymer in the intermediate layer closer to the support. There is no specific limitation to this ratio as long as the PVA/water soluble polymer ratio of the intermediate layer closer to the top layer_, is higher than the PVA/water soluble polymer ratio of the intermediate layer closer to the support. Preferably the ratio of PVA-based polymer and water soluble polymer in said layer closer to the top layer is at least 1:1, more preferably at least 3:2, most preferably at least 2:1. The PVA- based polymer(s) are preferably applied to the substrate in a total amount preferably ranging from 0.5 until 15 g/m² and more preferably from 1.0 until 10 g/m². The water soluble polymer of the present invention can be selected from: hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, any gelatin (including lime- or acid-processed, recombinant or chemically modified gelatin, made from animal collagen, e.g. made from pig skin, pig bone, cow skin, cow bone or fish), polyethylene oxide, polyacrylamide, and combinations thereof. In case a modified gelatin is applied as water soluble polymer the modified gelatin can be selected from the group consisting of acetylated gelatin, hydrolysed 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. The composition of the intermediate layers comprising a PVA-based polymer and a water soluble polymer can be the same or different. The water soluble polymer of the intermediate layers can also be a PVA-based polymer as long as it is not the same compound as the other PVA-based polymer present in the same layer depending on the properties one likes to achieve. Depending on the properties to be achieved, intermediate layers may also be used in addition to the layers comprising PVA-based polymers that comprise water soluble polymers without the use of PVA-based polymers. Examples of polymers that may be comprised by these additional intermediate layers include: hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, any gelatin whether lime- acid-processed, recombinant or chemically modified, made from animal collagen, (e.g. made from pig skin, pig bone, cow skin, cow bone or fish), polyethylene oxide, poly aery lamide, and the like. The total amount of water soluble polymers is preferably from 1.0 to 30 g/m² and more preferably from 1.0 to 20 g/m². The number of intermediate layers comprised in the multilayer is not specifically limited and depends largely on the available technique for application of the layers and the required ink receiving properties of the ink receiving layer. The ink receiving multilayer may comprise 3 to 26 and more preferably 3 to 18 sub-layers. One or more of the intermediate layers may further comprise a UV stabiliser. Any UV stabiliser known in the art can be added. Suitable UV agents are selected from the group consisting of purine compounds, pyrimidine compounds, benzimidazole compounds, imidazolidine compounds, urazole compounds, pyrazole compounds, triazole compounds, benzotriazole compounds, tetrazole compounds, pyrazine compounds, cinnamate compounds, aminobutadiene compounds and mixtures thereof. Examples of UV agent are those described in Research Disclosure RD24239, RD290119, RD30326, EP-A 0 673 783, GB-A 2088 777, EP-A 0955180, EP-A-0 738 718, US-A-4926190 and in Ullmann's Encyclopedia of Industrial Chemistry, 5^th completely revised edition 1992, volume 20, page 468-471. Other suitable UV agents are compounds containing a triazine skeleton. These compounds are described, for example, in JP-A-46-3335, JP-A- 55-152776, JP-A-5-197074, JP-A-5-232630, JP-A-5-307232, JP-A-6-211813, JP- A-8-53427, JP-A-8-234364, JP-A-8-239368, JP-A-9-31067, JP-A-10JP-A-10- 147577, JP-10-182621, JP-T-8-501291 ("JP-T" means published searched patent publication). EP-A-0711804 and DE-A- 19739797 are preferable. Preferred UV agents are benzotriazole compounds, such as 2-(2- hydroxy-5'methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t- butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzot riazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t- butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-sec-butyl-5'-t- butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-sec-butyl-5'-t-butylphenyι)-5- chlorobenzotriazole, 2-(2'-hydroxy-4'-n-hexyloxyphenyl)benzotriazole, 2-(2'- hydroxy-5'-isoocytlphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t- amy lp he nyl)benzo triazole, 2-(2'-hydroxy-5'-isooctylphenyl)-5'-methyl- benzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl) benzotriazole, 2-(2'-hydroxy- 3'-t-butyl-5'mehtylphenyl)benzotriazole, 2-(2'-hydroxy-3'-sec-dodecyl- 5'mehtylphenyl) benzotriazole, as well as the benzotriazole compounds described in EP-A-0 738 718, the benzotriazole compounds described in US-A- 4926190, and mixtures thereof. The UV agent can be added in a suitable solvent or as a component of an oil in water emulsion. Also UV agents linked to gelatin can be used. The UV agent may be added in the amount from 0.03 g/m² to 10 g/m², preferable between 0.03 g/m² and 5 g/m². The ink receiving layer may further comprise an optical brightener. Suitable optical brighteners are disclosed in e.g. RD11125, RD9310, RD8727, RD8407, RD36544 or Ullmann's Encyclopedia of industrial chemistry (Vol. A18 p 153- 167), and comprise thiophenes, stilbenes, triazines, imidazolones, pyrazolines, triazoles, bis(benzoxazoles), coumarins and acetylenes. The optical brightener can be added in a suitable solvent or as a component of an oil in water emulsion. Also optical brighteners linked to gelatin can be used. The optical brightener may be present in the ink receiving layer in an amount of 0.01 to 5.0 gram/m², preferably of 0.02 to 1.0 gram/m². One or more of the intermediate layers may further comprise 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 cation aluminum oxide or its hydrate and pseudo-boehmite), a surface-processed cation 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 fiuoro 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- fluoroethylamine hydrochloride, 2-fluoro-l-methyl pyridinium-toluene sulfonate, 4-fluorophenethylamine hydrochloride, fluorophenylhydrazine hydrochloride, l-(2-fluorophenyl) piperazine monohydrochloride, 1 -fiuoro pyridinium trifluoromethane sulfonate. - one of more light stabilising agents. Useful agents are: sterically hindered phenols, sterically hindered amines, and compounds as disclosed in

GB2088777, RD 30805, RD 30362 and RD 31980. Especially suitable are water-soluble substituted piperidinium compounds as disclosed in WO02055618. - one ore more 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 adjusting agents; • anti-mildew agents, anti-fungal agents • viscosity modifiers; • dispersing agents; • anti-oxidants; • radical scavengers; • 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, stabilising agents, conventional additives) may be added in a range of 0 to 30% by weight of total additive, based on the solid content of the water soluble polymers and PVA-based polymers in the ink receiving layer. 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. Although the lightfastness of the images on the recording medium is much improved by the use of a PVA-based polymer, the gloss of the recording medium, if a PVA-based polymer is also applied together with a water soluble polymer in the top layer viz. the layer farthest from the base, is not very high. It was surprisingly found that using a top layer comprising a modified gelatin on top of the layers comprising the PVA-based polymer improves the gloss of the recording medium considerably. When a very high gloss is desired the use of a modified gelatin in the top layer is preferred. Preferred are modified gelatins in which at least part of the NΗ₂ groups is chemically modified. A variety of modified gelatins can be used like phtalated and acetylated gelatins and the like. 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 20 C atoms. This aliphatic chain can be modified still to adjust the properties such as the water solubility and ink receptivity. Specially 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 20 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. Other suitable methods for obtaining the modified gelatin are described in EP-A-0 576 911, 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 vol.: 200, 1998, 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. The modified gelatin is preferably used in an amount of 0.1 to 5.0 g/m², more preferably from 0.2 to 4.0 g/m². The top layer furthermore determines other surface properties like beading, slip behaviour and the like. To obtain excellent surface properties it may be desirable to add in the top layer an anti-blocking agent to prevent image transfer when several printed inkjet media are stacked. 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 preferably from 0.01 to 1 g/m², more preferably from 0.01 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 alky l(meth) aery late, an alkoxyalkyl(meth)acrylate, 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, organic matting agents can be used 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, 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. A further improvement can be obtained by including in the top layer a fluorosurfactant. 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 term "fluorosurfactant" as used herein, refers to surfactants

(viz. molecules having a hydrophilic and a hydrophobic part) based on hydrocarbons, which hydrocarbons are substituted with at least one F atom. Suitable fluorosurfactants may be anionic, non-ionic or cationic. Examples of suitable fluorosurfactants are: fiuoro C2-C1O alkylcarboxylic acids and salts thereof, disodium N-perfluorooctanesulfonyl glutamate, sodium 3-(fluoro-C6- C11 alkylaxy)-l-C3-C₄ alkyl sulfonates, sodium 3-(omega -fluoro-CG-Cβ alkanoyl- N-ethylamino) - 1 -prop ane sulfonate s, N- [3- (perfluorooctanesulfonamide) - propyl]-N,N-dimethyl-N-carboxymethylene ammonium betaine, fluoro-C₁₁-C2o alkyl carboxylic acids and salts thereof, perfluoro alkyl carboxylic acids (e.g. perfluoro C7-Ci3 alkyl carboxylic acids) and salts thereof, perfluorooctane sulfonic acid diethanolamide, Li, K and Na perfluoro C₄-Ci2 alkyl sulfonates, Li, K and Na N-perfluoro C -Cι₃ alkane sulfonyl-N- alkyl glycine, Zonyl™type of fiuoro surfactants as supplied by Dupont, 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 Cβ-Cio alkylsulfonamide propyl sulfonyl glycinates, bis-(N-perfluorooctylsulfonyl-N- ethanolaminoethyl)phosphonate, mono-perfluoro Cβ-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-Ci3 alkane sulfonyl -N- alkyl glycine, Zonyl™ surfactants and 1,4-bis (fiuoro alkyl) - 2-[2-N,N,N-trialkylammonium alkyl amino] butanedioate. The toplayer may optionally include thickener agents, biocides, crosslinking agents and further various conventional additives such as colorants, coloured pigments, pigment dispersants, mold lubricants, permeating agents, fixing agents for ink dyes, anti-oxidants, dispersing agents/non-fluorosurfactants, 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. Optionally the top layer can further comprise one or more water soluble polymers and/or other additives to optimise the surface properties. The above-mentioned various additives can be added ordinarily in a range of 0 to 10 weight % based on the solid content of the ink receiving layer composition. In case a modified gelatin is applied the amount of modified gelatin in the top layer preferably ranges from 0.1 to 2 g/m² and more preferably from 0.2 to 1.0 g/m². If desired, the water soluble polymer(s) and/or the PVA based polymer(s) of the ink receiving layer can be cross-linked 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 chloropentanedione, 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-based polymers, for example, it is preferable to choose a cross-linking agent selected from borax, glyoxal, dicarboxylic acids and the like.

A process for providing the inkjet media of the present invention comprises the steps of providing a substrate and applying the formulations of top layer and intermediate layers thereto, preferably in the form of an aqueous solution, to which other optional ingredients may be added. These formulations are at least a first solution for the toplayer of said medium, a second solution comprising a water soluble polymer and a PVA based polymer and a third solution comprising a water soluble polymer and a PVA based polymer which both can be the same or different from the water soluble polymer or the PVA based polymer as used in the second solution, wherein the ratio of said PVA- based polymer/water soluble polymer in the second solution is higher than the ratio of PVA-based polymer/water soluble polymer in the third solution. The formulations for the toplayer and the intermediate layers can be coated consecutively or simultaneously to a support by any method known in the art resulting in a medium having one toplayer and at least two layers located in between said toplayer and said support comprising the water soluble polymer(s) and the PVA based polymer(s) from the second and third solution. The coating methods are for example, a curtain coating, an extrusion coating, a slide coating and the like. Generally it will be necessary to coat one or more layers on the backside of the support, i.e. the side of the support opposite to the side coated with the ink receiving layer, for instance to optimise the curling behaviour of the medium, which curling especially occurs at low humidity conditions due to contraction of the polymers during drying. The backside coating typically 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, even more preferably from 5 to 13.5 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. The preferred polymer for the backside coating is gelatin. In a special embodiment also on the backside an ink receiving layer is coated creating a medium which is printable on both sides. As stated above, the use of a modified gelatin improves the gloss of the recording medium significantly. Surprisingly it has been found that the gloss of the medium can be improved further by selecting the appropriate surface roughness of the used substrate. 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. The Ra is measured according to DIN 4776 by a UBM laserprofilometer, 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. 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, BaS0 , and the like can be used. 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 polymer 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, Tiθ2, BaS0₄, 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 g/m². This pigmented coating can be applied as a pigment slurry in water together with a suitable binder 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 below 1.0 μm, more preferably below 0.8 μm. The ink receiving multilayer of the present invention can be directly apphed 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. Ti0₂ (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 colours 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. Other supports used in this invention may suitably be selected from, a synthetic paper or a plastic film in which the top and back coatings are balanced in order to minimise the curl behaviour. 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 have a gelatin subbing layer to improve coatabihty 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 ink-receiving layer preferably has a dry thickness from 1 to 50 micrometers, more preferably from 5 to 30 and even more preferably between 8 and 25 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 recording medium of the invention can be used for forming a permanent, precise inkjet image by bringing ink into contact with the medium in the pattern of a desired image. The recording medium of this invention can be used in any printing apphcation, where a photographic quality print 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, xerography, and the like. The media of the present invention 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 gloss. 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 modified gelatin solution-A A solution containing 100 weight parts of modified gelatin (dodecenyl-succinic modified acid treated gelatin from Stoess GmbH, Germany, modification grade 40%) having an IEP of 5.4, 1 weight part of Zonyl^® surfactant (a fluoro-carbon type of surfactant, DuPont, U.S.A.), and 899 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 a lime bone gelatin solution B A solution containing 100 weight parts of lime bone gelatin of PB Tessenderlo with an IEP of 5.0 and 900 weight parts of water was prepared at 40°C. The pH of the solution was adjusted to 8.5 by adding NaOH.

C. Preparation of the PVA solution-C

A solution containing 100 weight parts of polyvinyl alcohol (Mowiol® 8-88, Kuraray Specialties Europe) and 900 weight parts of water was prepared at 85°C. The pH of the solution was adjusted to 9.0 by adding NaOH.

D. Preparation of the modified PVA solution-D A solution containing 100 weight parts of PVA-NVF co polymer (CGPS-910, melting range 210-230 °C, Ciba Specialty Chemicals, Swiss) and 900 weight parts of water was prepared at 85°C. The pH of the solution was adjusted to 9 by adding NaOH.

Schematic drawing and definition of the layer structure The ink receiving layer consists of at least three intermediate layer and one top layer as shown in the scheme below.

Example 1 (comparative) For the toplayer 1 weight part of Zonyl^® FSA surfactant (a fluoro- carbon type of surfactant, Ciba Specialty Chemicals, Swiss) was added to 1000 weight parts of Solution-B to provide a good wettability. For the intermediate layers 1-3 the solution-B was used as it was. The compositions were fed into a slide coating machine, commonly known in the photographic industry, and coated on a photographic grade paper having pigments coated on one side and polyethylene laminated at both sides (laminated substrate). The flow was adjusted such that, after drying, the total solid content of the toplayer was 1.0 g/m², that of the intermediate layer 1 was 3.0 g/m², that of the intermediate layer 2 was 3.0 g/m², and that of the intermediate layer 3 was 8.0 g/m². After coating, the coated material was chilled at a temperature of ca. 12°C to set the gelatin containing solution and then dried with dry air at a maximum temperature of 40°C. Example 2 (comparative) The ink receiving layers were produced in the same manner as in Example 1, except that for the toplayer solution-A and for the intermediate layer 1 the mixture of the solution-B and the solution D having the weight ratio of 1:2 was used.

Example 3 (comparative) The ink receiving layers were produced in the same manner as in Example 2, except that for the intermediate layers 1 and 3 solution-B and for the intermediate layer 2 the mixture of the solution-B and the solution C having the weight ratio of 1:1 was used. Example 4 (inventive) For the toplayer 1 weight part of Zonyl^® FSA surfactant (a fluoro- carbon type of surfactant, Ciba Specialty Chemicals, Swiss) was added to 1000 weight parts of Solution-A to provide a good wettability. For the intermediate layer 1 the mixture of the solution-B and the solution D having the weight ratio of 1:2 was used. For the intermediate layer 2 the mixture of the solution-B and the solution D having the weight ratio of 1:1 was used. For the intermediate layer 3 the solution-B was used as it was. The coating and the drying process was done in the same manner as in Example 1. Example 5 (inventive) The ink receiving layers were produced in the same manner as in Inventive Example 4, except that for the intermediate layer 1 the mixture of the solution-A and the solution D having the weight ratio of 1:2 was used. Example 6 (inventive) The ink receiving layers were produced in the same manner as in Inventive Example 4, except that for the intermediate layer 1 the mixture of the solution-B and the solution D having the weight ratio of 1:3 was used.

Example 7 (comparative) The ink receiving layers were produced in the same manner as in Inventive Example 4, except that for the intermediate layer 1 the mixture of the solution-A and the solution D having the weight ratio of 1:1 was used and for the intermediate layer 2 the mixture of the solution-B and the solution D having the weight ratio of 1:2.

Evaluation 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 ^® 5650 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 was analysed visually by analysing the light and ozone fastness behaviour, the glossiness of especially the black area, the dryness of especially the black area, and on haze in black.

Raw gloss Raw gloss is a glossiness of coated composition without print. The glossiness was measured by a REFLEKTOMETER, REFO 3-D gloss meter (Dr. Lange) and evaluated according to the following criteria.

O: glossiness of 20° >= 70% Δ: glossiness of 20° is between 40% and 70% X: glossiness of 20° < 40%

Haze in black Haze in black is a hazy appearance in 'black' printed parts (or dark coloured high density parts) after drying. It depends on the printer's ink composition and especially on the amount of ink used. The haze in black can be observed independent from the way how the black is obtained, whether by mixing cyan, magenta, and yellow inks, or directly printing black ink. 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: Slightly hazy after drying, but acceptable. X: Matte appearance after printing, or severely hazy after drying.

Light fastness Light fastness is a measure for the dye stability during the display or storage at (ambient) hght conditions. In order to evaluate this behaviour a sample was dried for one week after printing at ambient temperature and humidity and subsequently exposed for 504 hrs using a xenon light (85 000 lx) in an Atlas Wether-O-Meter C I 35A, (manufactured by Atlas (Illinois, U.S.A.)), using a cycle of 228 min. light on with a temperature of 40 °C and a relative humidity (RH) of 24% and a period of 60 min. light off at a temperature of 27 °C and a RH of 40%. The image density of the colour 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 overall performance of the light fading properties is judged based on the loss of image density of the cyan, magenta and yellow colours and on the neutrality of the grey tone. The following classification has been defined: O: good Δ: acceptable X: not acceptable

Ozone fastness Ozone fastness is a measure for the dye stability during the display at (ambient) atmosphere exposed conditions. In order to evaluate this behaviour a sample was exposed for 96 hrs under 2.5 ppm of ozone concentration in an ozone chamber OTC-1 (manufactured by In U.S.A.). The image density of the colour 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: 95% or more residual percentage Δ: 85-95 residual density X: less than 85% of residual density Drying speed Directly after printing the standard pattern, a white plain paper was overlaid on the printed sheet and a stainless steel roller with a weight of 10 kg was rolled over the white paper slowly. The drying speed of the ink -jet sheet was determined by analysing visually the colour density of the print which was transferred to the white paper. A lower density at the white paper means a better drying speed of the ink -jet solvent. Definition: O = Good Δ = Not totally dry but still acceptable X = Bad (not acceptable)

All results are summarized in Table- 1. Table- 1

Example 2 shows that only one intermediate layer containing modified PVA in a ratio of 2:1 with gelatin is not sufficient to achieve a good light fastness although it is present in the layer closest to the toplayer. To obtain good results at least two layers should contain a PVA based polymer. Comparing examples 4, 5 and 6 shows that the best results are obtained when the layer closest to the toplayer has the highest PVA/gelatin ratio.

Claims

1. Recording medium comprising a support and an ink-receiving layer adhered to said support, wherein the ink-receiving layer is a multilayer comprising a top layer and two or more intermediate layers between said support and said top layer, wherein at least two of said intermediate layers comprise a mixture of at least one poly vinyl alcohol (PVA) -based polymer and at least one water soluble polymer, wherein the ratio of said PVA-based polymer/water soluble polymer in the intermediate layer closer to said top layer is higher than the ratio of PVA-based polymer/water soluble polymer in the intermediate layer closer to said support. 2. Medium according to claim 1 comprising the same or different PVA- based polymers in said at least two intermediate layers and/or the same or different water soluble polymers in said at least two intermediate layers.

3. Medium according to any of the previous claims, wherein said PVA- based polymer is selected from the group consisting of fully hydrolysed or partially hydrolysed PVA, carboxylated PVA, acetoacetylated PVA, quaternary ammonium modified PVA, copolymers and terpolymers of PVA with other polymers, and combinations thereof.

4. Medium according to any of the previous claims wherein the total amount of the PVA-based polymer is from 0.5 to 15 g/m², preferably from

1.0 to 10 g/m².

5. Medium according to any of the previous claims, wherein said water soluble polymer is selected from the group consisting of: hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, gelatin, modified gelatin, recombinant gelatin, polyethylene oxide, poly aery lamide, and combinations thereof. 27

Claims

1. Recording medium comprising a support and an ink-receiving layer adhered to said support, wherein the ink-receiving layer is a multilayer comprising a top layer and two or more intermediate layers between said support and said top layer, wherein at least two of said intermediate layers comprise a mixture of at least one poly vinyl alcohol (PVA) -based polymer and at least one water soluble polymer, wherein the ratio of said PVA-based polymer/water soluble polymer in the intermediate layer closer to said top layer is higher than the ratio of PVA-based polymer/water soluble polymer in the intermediate layer closer to said support.

2. Medium according to claim 1 comprising the same or different PVA- based polymers in said at least two intermediate layers and/or the same or different water soluble polymers in said at least two intermediate layers.

1.0 to 10 g/m².

5. Medium according to any of the previous claims, wherein said water soluble polymer is selected from the group consisting of: hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, gelatin, modified gelatin, recombinant gelatin, polyethylene oxide, polyacrylamide, and combinations thereof. 28

6. Medium according to any of the previous claims wherein at least one of said water soluble polymers is a gelatin selected from lime treated or acid treated bone or hide gelatin of pig, cattle or fish, modified gelatin, recombinant gelatin, and combinations thereof.

7. Medium according to any of the previous claims wherein the ink receiving layer comprises a 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.

8. Medium according to any of the previous claims wherein at least one of the PVA-based polymers is a PVA-NVF polymer according to formula I:

(I) wherein n is between 0 and 20 mole percent; m is between about 50 and 97 mole percent; x is between 0 and 20 mole percent; y is between 0 and 20 mole percent; z is between 0 and 2 mole percent and x -y is between about 3 and 20 mole percent; Ri, and R3 are independently H, 3-propionic acid or Ci-Cβ alkyl ester thereof, or is 2-methyl-3-propionic acid or Ci-Cβ alkyl ester thereof; and R2 and R₄ are independently H or Ci-Cβ alkyl.

9. Medium according to claim 1 wherein the ink receiving layer in addition to the intermediate layers comprising a PVA-based polymer 29

further comprises one or more layers comprising a water soluble polymer selected from the group of hydroxyethyl cellulose, methyl cellulose, hydroxypropyl cellulose, polyvinylpyrolidone, any gelatin whether lime or acid treated bone or hide gelatin of pig or cattle or fish, modified gelatin, recombinant gelatin, polyethylene oxide, polyacrylamide, and combinations thereof.

10. Medium according to any of the previous claims, wherein the total amount of water soluble polymers is from 1.0 to 30 g/m², preferably from 1.0 to 20 g/m².

11. Medium according to any of the previous claims, in which the number of layers of said multilayer is from 3 to 26, preferably from 3 to 18.

12. Medium according to any of the previous claims wherein the multilayer further comprises a UV absorbing agent, an anti-oxidant, an optical brightener, a light stabilizer, a radical scavenger, a surfactant, a fiuoro surfactant or combinations thereof.

13. Medium according to any 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 substrate.

14. Medium according to any of the previous claims wherein the support has a surface roughness Ra, as determined according to DIN 4776, smaller than 1.0, preferably smaller than 0.8.

15. Process for preparing a recording medium, comprising the steps of providing at least a first, a second and a third solution, - the first solution for the toplayer of said medium; the second solution comprising a water soluble polymer and a PVA based polymer, the third solution comprising a water soluble polymer and a PVA based polymer which both can be the same or different from the water soluble polymer or the PVA based polymer as used in the second solution; 30 wherein the ratio of said PVA-based polymer/water soluble polymer in the second solution is higher than the ratio of PVA-based polymer/water soluble polymer in the third solution; followed by a step wherein said solutions are applied to a support to provide a medium having at least one toplayer and at least two layers located in between said toplayer and said support comprising the water soluble polymer(s) and the PVA based polymer(s) from the second and third solution.

16. A method of forming a permanent, precise ink -jet image comprising the steps of: providing a recording medium as defined in any of the claims

1- 14; and bringing ink-jet ink into contact with the medium in the pattern of a desired image.