GB2400335A

GB2400335A - Recording materials

Info

Publication number: GB2400335A
Application number: GB0308036A
Authority: GB
Inventors: Jonathan James Osborn; Amanda Mary Upton; Michael Alan Wraith
Original assignee: Ilford Imaging UK Ltd
Current assignee: Ilford Imaging UK Ltd
Priority date: 2003-04-08
Filing date: 2003-04-08
Publication date: 2004-10-13
Also published as: GB0308036D0

Abstract

An inkjet recording material comprises a substrate and an ink receiving coating applied thereto, consisting of silica particles in a binder of gelatin and a cationic polyvinyl alcohol derivative. The ratio of silica particles to binder is typically between 5:1 and 1.3:1 and is preferably between 1.5:1 and 1.3:1. The silica particles may be between 1 and 25 microns in size. The polyvinyl alcohol derivative may be a vinylalcohol / vinylamine copolymer with a molecular weight range of 10000 to 170000 and comprising ca. 20% vinylamine. The said copolymer may be prepared by the copolymerisation of a vinyl acetate and an N-vinyl amide followed by hydrolysis.

Description

Recording Materials

Field of the Invention

The present invention relates to a recording material for recording using the ink jet printing process.

Background of the Invention

Ink jet recording is a non-impact printing method wherein droplets of a recording fluid, the ink, are formed by forcing the fluid through a tiny nozzle (or a series of nozzles) under computer control and deposited on a recording material such as paper or transparent film.

There are several classes of ink jet printer, for instance thermal dropon-demand printers, piezo drop-on-demand printers, and continuous ink jet printers. Ink jet recording has been intensively developed in recent years, and has found broad application as output for personal computers in the office and the home because of its low noise characteristic, capability of high speed printing, and facility of multi-colour printing. Ink jet printing techniques have undergone rapid development both in respect of reliability and the image quality that the printing apparatus can achieve, and in respect of the cost price of the printing apparatus. Consequently, increasingly severe requirements are being set for the recording materials.

Ink jet printers, particularly those aimed at use in the office or home, generally employ mainly aqueous inks, and various water soluble anionic dyes have been employed as colorants for these inks. Recording materials suitable for use with such dyed inks are well known, and typically comprise at least one water receptive polymeric binder, often in combination with a cationic fixing agent for the anionic dye. For instance United States Patent 4,801,497 discloses a recording medium comprising an ink receiving layer provided on a substrate, wherein said ink receiving layer contains a cationically modified product of polyvinyl alcohol and a water soluble polymer having no active hydrogen. Similarly United States Patent 5,662,997 describes an ink jet recording film comprising cation-modified polyvinyl alcohol and a recording method using the same.

Also, European Patent Application 0 869 010 A describes a recording sheet for ink jet printing comprising a support having coated onto said support one or more layers receptive for aqueous inks, said recording sheet being characterized in that the coating comprises at least one polyvinyl alcohol/ polyvinylamine copolymer; this material provides prints of good water fastness and light stability when printed with dye based aqueous inks.

Further, it is also known to provide recording materials for ink jet printing comprising an absorptive inorganic pigment in addition to the binder and cationic fixing agent. For instance United States Patent 5,213, 873 describes a combination of silica particles with polyvinyl alcohol and cationic water soluble acrylic polymers and United States Patent 6,129,785 discloses a coating composition for an ink jet recording medium comprising an aqueous suspension of absorptive silica pigment, a polyvinyl alcohol binder, and a cationic fixing agent. Similarly United States Patent 6,174,056 discloses an image forming method by applying a colour ink to a glossy recording medium having a porous structure including a pigment, a binder, and a cationic material and United States Patent 6,485,609 discloses an ink jet printing paper containing an amine functional poly (vinyl alcohol) . Such recording materials provide prints and images of good quality when printed with dye based inks, and are suitable for their intended purposes. However it has become more common recently to use pigments as the colorants for ink jet inks instead of, or sometimes in addition to, dyes. By the term pigment is meant a colorant which is essentially insoluble in use. Consequently there is increasing interest in providing recording materials which are suitable for use with pigmented inks, and particularly in recording materials which are suitable for use with both dyed and pigmented inks.

IIowever use with pigmented inks introduces requirements on the recording materials which are not well met by many of those known in the art. For instance, it is difficult to achieve bright saturated colours from pigmented inks because pigments generally have duller hues than many of the dyes hitherto commonly used in inks. Thus it is important when designing a material for use with pigmented inks to attain the maximum possible colour gamut from the inks in use. We have developed such a material.

SummarY of the Invention

According to this invention there is provided a recording material suitable for ink jet recording comprising a sheet like substrate and arranged on at least one side of the substrate at least one ink-receptive recording layer comprising: À silica; and À a water receptive polymeric binder comprising gelatin and at least one cationic polyvinyl alcohol derivative; wherein the ratio of the dry coating weight of the silica to the total dry coating weight of the binder is between 5:1 and 1 3:1.

Detailed Description of the Invention

The supporting substrate for the recording materials of the invention may be any of those known for use in printing and imaging media. Suitable substrates include, for example paper, high wet-strength paper, tracing paper, heavyweight paper, fine art paper, card, board, coated paper such as resin coated, polyethylene coated, and barrier layer coated paper, synthetic papers, canvas, cloth, fabric, metals such as aluminium, and polymeric substrates such as filled plastics, opaque plastics, or transparent materials, for example cellulose acetates, poly(ethylene), poly(propylene), poly (vinyl chloride), poly (ethylene terephthalate) and poly (ethylene naphthalate), polycarbonate, polysulphone, polyether sulphone, poly (arylene sulphone), poly(arylene ether ketone sulphone), cellophane, polyvinyl fluoride, polyimide, and the like. Such substrates are well known. Preferably the supporting substrate is a porous substrate and most preferably the substrate is a fine art paper or canvas, particularly a paper with a basis weight ranging from 40 to 500 gm2, preferably from 100 to 250 gm-2.

Any conventional paper prepared by sheet-making in the range as specified above can be used as substrate, for example, paper produced by various apparatus such as a Fourdrinier paper machine, a cylinder paper machine or a twin wire paper machine from a wood pulp including, for example, a chemical pulp, a mechanical pulp, or a waste paper pulp. The paper may be manufactured from a pulp comprising in addition optionally at least one of various conventional additives as are known in the art, for example including a filler or pigment, a binder, a sizing agent, a fixing agent, a yield-improving agent, a cationic agent and a paper strength- increasing agent. The filler content in the paper is preferably not more than 25% by weight, based on dry matter. Suitable fillers include, for example, starch or an inorganic pigment such as clay, talc, calcium carbonate, magnesium silicate, and the like.

The paper may optionally have internal and/or surface sizing with known sizes. Other additives known to those skilled in the art may be present such as a wet strength agent, dry strength agent, a foam suppressant, a deforming agent, or a biocide.

The silica for the ink receptive layer may be any particulate silica as is known for use in imaging layers, for instance natural silica, amorphous silica, synthetic silica such as precipitated or fumed silica, and chemically modified silica compounds. Porous amorphous synthetic fine particulate silica is particularly preferable. The average particle size of the silica may be up to 50 m, preferably from approximately 1 lam to 25,um. Synthetic silica in this size range suitable for use in ink jet receiving layers is commercially available.

Further, the silica may be subjected to a surface treatment with one or a mixture of two or more metal oxides, hydroxides, or salts, such as treatment with aluminium oxide or hydroxide, titanium oxide, or zirconium oxide.

The gelatin for the ink-receptive layer of the recording materials of the invention may be any gelatin known for use in imaging materials, for example skin or bone gelatin, such as acid pigskin or limed bone gelatin; treated gelatin such as deionised gelatin; modified gelatin such as phthalated, acetylated, or carbamoylated gelatin; acid or base hydrolysed gelatin; or a cationically modified gelatin. A particularly suitable gelatin is a deionised ossein gelatin.

The cationic polyvinyl alcohol derivative for the ink receptive layer is not particularly restricted, and any cationic polyvinyl alcohol derivative may be used. By cationic polyvinyl alcohol derivative is meant a polyvinyl alcohol which carries positive charge, for instance by carrying quaternary ammonium groups, or which is capable of carrying positive charge, for instance by carrying basic amino groups or substituted amino groups which may become protonated at the pH of the coating layer. Such cationic polyvinyl alcohol derivatives are known in the art and may be prepared by modification of a polyvinyl alcohol or by copolymerisation of a polyvinyl alcohol precursor such as vinyl acetate with suitable nitrogen containing comonomers.

A particularly preferred cationic polyvinyl alcohol derivative is a polyvinyl alcohol/ polyvinylamine copolymer, hereinafter referred to as PVAA. PVAA copolymers are known and may be prepared, for example, by polymerization of a combination of vinyl acetate with an N-vinyl amide such as N-vinyl formamide or N-vinyl acetamide and subsequent hydrolysis of the acetate and amide groups on the polymer. The PVAA copolymer may be a random copolymer or a block copolymer, but is preferably a random copolymer. Specific synthetic methods fopr PVAA copolymers are described in United States Patent 4,774,285 and in European Patent Applications 0 339 371 A and 0 869 010 A. The weight average molecular weight of the PVAA may be in the approximate range of 10,000 to 170,000, preferably from approximately 8,000 to approximately 110,000. The proportion of vinylamine in the copolymer may be up to 30 mole %, preferably between 10 and 20 mole %. The degree of hydrolysis of the acetate and amide groups may be at least 80%, preferably 90% or greater, and most preferably 98 - 99%.

The ratio of the dry coating weight of the cationic polyvinyl alcohol derivative and the gelatin is not particularly limited and may vary in the approximate range of 5:1 to 1:5, preferably in the range of 3: I to 1:3.

The ratio of the dry coating weight of the silica to the dry coating weight of the binder of the ink-receiving layer may be between 5:1 and 1 3:1. For the preferred porous substrates the ratio is preferably between 1 5:1 and 1 3:1. If insufficient binder is present the coated layer becomes fragile and powdery. On the other hand, if too much binder is present colour gamut is poor if pigmented inks are used and image quality is unacceptable.

The total coated amount of the ink-receptive layer may be determined according to the printing apparatus, the quantity of ink to be printed, the substrate, and the components used. A suitable total dry coating weight of the ink-receptive layer is up to about 50 gm-2, preferably in the approximate range of 5 am-2 to 20 gm-2, most preferably from 10 am-2 to gm-2. If the coating weight is insufficient the ink absorptivity of the recording layer is lowered, leading to image problems such as feathering and blurring.

There may also be present cross linking agents for the matrix forming binders. Crosslinking allows for the modification of the physical properties of the layers, in particular in robustness and resistance against physical damage.

Suitable cross linking agents include for example boric acid, aldehydes (such as formaldehyde, glyoxal or glutaraldehyde), N-methylol compounds (such as dimethylol urea or methylol-dimethylhydantoin), dioxane derivatives (such as 2,3-dihydroxy dioxane), active vinyl compounds (such as bis-(vinylsulphonyl) methyl ether or 1,3,5-trisacrylolyl hexahydro-s-triazine), active halogen compounds (such as 2,4-di-chloro-6hydroxy-s- triazine), epoxides, aziridines, carbamoyl pyridinium compounds or mixtures of two or more of the above mentioned crosslinking agents.

The ink receiving layers according to this invention are in general coated from aqueous formulations. It is in many cases necessary to add surfactants to those coating formulations to allow for smooth coating and evenness of the layers.

The surfactant used is not particularly limited. Examples of suitable surfactants include nonionic surface active agents such as alkylene oxide derivatives, for example polyethylene glycol alkyl or alkylaryl ethers, polyethylene glycol esters, or polyethylene glycol / polypropylene glycol condensates; glycidol derivatives such as alkenyl succinic acid polyglycerides or alkylphenol polyglycerides; aliphatic esters of polyhydric alcohols or sucrose; anionic surfactants comprising a sulphuric acid ester group or a phosphoric acid ester group, such as alkyl sulphuric acid esters, alkyl phosphoric acid esters and sulphated or phosphated polyethylene glycol alkyl or alkylaryl ethers; alkylsulphonates, alkylbenzenesulphonates, alkylnaphthalenesulphonates, Nacyl-N-alkyltaurines, dialkyl sulphosuccinates; and cationic surface active agents such as alkylamine salts, or aliphatic or aromatic quaternary ammonium salts (such as pyridinium or imidazolium salts). Further, fluorinated or pertluorinated derivatives of the above mentioned compounds or silicone surfactants are also suitable. Such surfactants are well known in the art.

In addition to the components already mentioned, it is to be understood that the ink-receptive layer or layers may advantageously also comprise further conventional additives as are known in the art for use in such layers, for example plasticisers, dispersants, antifoams, ultraviolet absorbers, stabilizers, biocides, thickeners, lubricants, latexes, antistatic agents, and water-resisting agents. Further, pH buffers may be present or the pH may be adjusted by addition of acids or bases as appropriate. The pH of the coating formulation may be between 3 and 10, and preferably the pH is in the range 5 to 7.

Also, in general the whiteness of the material should be as high as possible, and it may therefore be advantageous to include in the substrate and/or in the ink-receptive recording layer components such as optical brightening agents, dyes, or pigments to improve the brightness and whiteness of the paper. However the invention may also be used with coloured or tinted papers In addition, the ink receptive layers of the invention may also contain water soluble metal salts, for instance salts of Ca, Mg, or one of the rare earth metal series.

There may also be present in the ink-receptive layer or layers additional water receptive binders compatible with the gelatin and cationic polyvinyl alcohol derivative. Suitable binders may include poly vinyl alcohol; carbohydrates such as tragacanth gum, sodium alginate, or water- soluble starch derivatives; water-accepting cellulose derivatives such as hydroxyethyl cellulose, methyl hydroxypropyl cellulose, carboxymethyl cellulose, or carboxymethylhydroxyethyl cellulose; polyalkylene oxides such as polyethylene oxide and derivatives thereof; water-accepting acrylate, methacrylate, or maleate polymers and copolymers and derivatives thereof; poly (vinyl pyrrolidone) and copolymers and derivatives thereof; casein; and mixtures of such binders.

Optionally there may also be present additional layers in the recording material.

Specifically, the recording material of the invention may comprise two or more ink-receptive recording layers, any or all of which may comprise the inventive combination of gelatin, silica, and cationic polyvinyl alcohol derivative as hereinbefore described.

However one of the advantages of the present invention is that only a single coated I recording layer is required to provide recording materials of excellent properties.

Further, the back surface of the material may be left uncoated or may have a coating for lay-flat or for write on properties. Additionally, lubricants to promote paper transport in the printing apparatus may be added to the back layer. Alternatively, the ink-receptive layer or layers may be provided on both sides of the substrate.

If desired, the surface of the substrate may be treated prior to applying the coating layer in order to improve the adhesion of the recording layer to the substrate, but this is not generally necessary with the preferred porous substrates. Such treatment may include buffing, corona discharge, or the application of an undercoating or subbing layer to the surface of the support. Such subbing layers are known in the art.

Another advantage of the invention is that the ink-receptive layer or layers may l O conveniently be produced as an aqueous formulation and coated on to the substrate by any suitable coating means, such as immersion or dip coating, roll coating, air knife coating, extrusion coating, doctor blade coating, cascade coating, slide bead coaler, curtain coaler, rod coating, gravure coating, or spraying. An ink receiving system can be built up by several layers. These layers can be coated one after the other or simultaneously The recording materials disclosed herein are useful as receiving materials for ink jet printers. Therefore according to another aspect of the invention there is provided an ink jet recording method comprising the steps of ejecting droplets of an ink composition comprising at least a colorant and a carrier liquid onto the recording material of the invention to deposit the ink droplets onto the material in an imagewise pattern, thereby generating images on the material. Preferably the ink is an aqueous ink, that is to say an ink in which the carrier liquid is predominantly water, but may also comprise one or more water soluble organic cosolvent such as a polyhydric alcohol. Frequently the ink also comprises one or more surfactants. The materials of the invention are suitable for use with inks comprising dyes or pigments as colorants. Such inks are well known in the art. The materials of the invention are suitable for use with any type of ink jet printer, for instance a thermal drop-on-demand printer, a piezo drop-on-demand printer, or a continuous ink jet printer. The printer may be a desk top ink jet printer or a wide format ink jet printer. In a particularly preferred embodiment, the printing apparatus is a desk top drop-on-demand ink jet printer.

Although the recording materials disclosed herein have been referred to primarily as being useful for aqueous ink jet printers, they may also be used in any other printing or imaging process, such as printing with pen plotters, handwriting with ink pens, and with conventional printing processes such as flexographic printing and the like, provided that the ink employed to form the image is compatible with the ink-receptive layer of the recording sheet.

Brief Description of the Drawine

Figure I shows a colour gamut plot for the coloured test patches of the printed coatings A and C of examples I and 2. The gamut calculation in these examples provides a measure of the areas enclosed by the polygons of this figure: the greater area enclosed by the plot for coating C shows the greater gamut attained using the preferred PVAA copolymer.

The following examples will serve to illustrate the invention.

Example I I

An inventive recording material was prepared using a coating formulation comprising the components given in Table 1.

Table 1

Component % by weight Deionised water 27 7 Deionised ossein gelatin 3 3 I Surfactant 2 0 Glycerol 1 1 10% cationic PVOH 22 1 Silica 43 2 4% sodium hydroxide solution 0 6 Total 100 The surfactant was a 50% solution in water of nonylphenoxypolyglycidol commercially I available from Olin Chemicals as Olin 10G. The cationic PVOH was Gohsefimer K210 commercially available from Nippon Gohsei, the 10% solution also contained 0 005% p-chloro-m-cresol as biocide. The silica was Sylojet P412 commercially available from Grace Davidson having an average particle size of 12 rim. Glycerol was present as a plasticiser. The sodium hydroxide solution adjusts the pH to approximately 7. This formulation was coated on 240 am-2 fine art paper substrate to provide coating A having a dry coating weight of 13 1 gm-2. The dry coating weight ratio of gelatin to the cationic PVOH is 1 5: 1 and the ratio of silica to total binder is 1 4: 1.

A comparison coating was prepared using the components given in Table 2.

Table 2

Component % by weight Deionised water 12 3 Deionised ossein gelatin 1 38 Surfactant 2 0 Glycerol 1 08 10% cationic PVOH 43 85 Silica 38 62 4% sodium hydroxide solution 0 77 Total 100 The surfactant, silica, and PVOH were the same as in coating A. The sodium hydroxide solution adjusts the pH to approximately 7. In this formulation the dry coating weight ratio of gelatin to the cationic PVOH is 1:3 2 and the ratio of silica to total binder is 1 2:1. This formulation was coated on the art paper substrate at the same dry coating weight as coating A to produce comparative coating B. The coated samples were printed with a test pattern including 100% density yellow, magenta, cyan, black, blue, green, and red test patches using pigmented inks and an Epson C80 ink jet printer set at 1440dpi with plain paper media photo quality setting and no colour adjustment. The density and CTELAB L* a* b* calorimetry values for the 100% density patches of the prints were measured using a Gretag Specrolino reflectance calorimeter using D65 illuminant and 2 Standard Observer. Under the L* a* b* calorimetry system the a* value is a measure of the colour along the green/red axis, with a negative value being greener, and the b* value is a measure of the colour along the blue/yellow axis, with a negative value being bluer. The results for the inventive material are shown in table 3 and for the comparison material in table 4; the white measurement is of a section of unprinted material.

Table 3

Coating A CIELAB colorimetry values Invention L a b* Cyan 47 63 -9 39 -48 91 Magenta 49 83 65 20 -9 79 Yellow 92 76 -11 48 99 79 Black 24 11 0 74 2 12 Red 5188 53 07 32 71 Green 45 25 -47 98 14 92 Blue 33 21 13 62 -37 87 White 97 09 -0 26 3 78

Table 4

Coating B CIELAB colorimetry values Comparison L* a* b* Cyan 50 42 -9 79 48 15 Magenta 52 21 62 89 -12 73 Yellow 92 74 -11 50 97 87 Black 22 42 0 71 2 13 Red 53 79 50 13 32 37 Green 47 33 -45 90 16 00 Blue 37 44 11 53 38 08 White 97 46 0 70 - 1 16 The colour gamut for each print was calculated as follows: segment lengths were calculated from the a* and b* figures for yellow (y), magenta (m), cyan (c), red (r), green (g), and blue (b) patches using the formulae: segment cm = [(a*(c) - a*(m))2 + (b*(c) - b*(m))2]'' segment cy = [(a*(c) - a*(y))2 + (b*(c) - b*(y))2]'' segment my = [(a*(m) - a*(y))2 + (b*(m) - b*(y))2]'' segment cg = [(a*(c) - a*(g))2 + (b*(c) - b*(g))2] segment cb = [(a*(c) - a*(b))2 + (b*(c) b*(b))2]A segment mr = [(a*(m) - a*(r))2 + (b*(m) - b*(r))2] ; segment mb = [(a*(m) - a*(b))2 + (b*(m) - b*(b))2]' segment yr = [(a*(y) - a*(r))2 + (b*(y) - b*(r))2] segment yg = [(a*(y) - a*(g))2 + (b*(y) - b*(g))2]' triangles from these segments were calculated using the formulae: triangle cmy = '/2(cm + cy + my); triangle rmy = '/2(my + mr + yr) triangle gcy = i/2(cy + cg + yg); triangle bcm = '/2(cm + cb + mb) And gamut = [cmy(cmy-cm)(cmy-cy)(cmy-my)]l'2 + [rmy(rmy- my)(rmy-mr)(rmy-yr)] + [gcy(gcy-cy)(gcy-cg)(gcy-yg)]I'+ [bcm(bcm-cm)(bcm-cb)(bcm-mb)] This calculation gives a measure of the available colour space; the larger the resultant number the greater the accessible colour gamut. It is desirable that the gamut should be as great as possible, but under these circumstances a figure of at least 9000 is necessary for acceptable performance in use; for the inventive material it is 9392 and for the comparison 8902 which is unacceptably low.

Example 2

An inventive recording material was prepared from a coating formulation comprising the components given in Table 5. This formulation differs from the formulation for coating A by replacement of the cationic PVOH by the preferred PVAA polyvinylamine/ polyvinyl alcohol copolymer having a vinylamine/ vinyl alcohol ratio of 15:85 and a cation content 3 4 meq/g. The surfactant and silica were the same as in coating A. Phenol was present as a biocide. The sulphuric acid was added to adjust the pH to approximately 7.

Table 5

Component % by weight Deionised water 24 3 Phenol 20% solution 0 3 Delimed ossein gelatin 3 3 Surfactant 2 0 Glycerol 1 1 PVAA copolymer 10% solution 22- 1 Silica 18% dispersion 43 2 Sulphuric Acid 3 7 Total 100 This formulation was coated on the art paper substrate to provide a dry coating weight of 13 25 gm-2. This is coating C; the dry coating weight ratio of gelatin to PVAA is 1 5:1 and the ratio of silica to total binder is 1 4:1. The coating was printed with a test pattern and the colour measured as in example 1. The results are given in table 6.

Table 6

Coating C CIELA B colorimetr: r values l Invention L* a* b* Cyan 46 24 -7 95 -51 31 Magenta 49 71 67 03 -10 63 Yellow 92 97 -12 30 98 91 Black 24 75 0 58 0 66 Red 51 25 54 77 34 33 Green 43 68 -50 05 14 39 Blue 30 57 17 36 -40 75 White 97 00 -0 22 3 79 The gamut was calculated as in example 1, it is 9963. The a* and b* values for the coloured test patches of the printed coatings A and C are plotted in figure 1: the greater area enclosed by the plot for coating C shows the greater gamut attained using the preferred PVAA copolymer.

The inventive coated samples A and C were also printed with dye based inks using an Epson 870 printer. Again a test pattern including 100% density yellow, magenta, cyan, black, blue, green, and red test patches was used and the printer was set at 1440dpi with plain paper media photo quality setting and no colour adjustment. The density of the 100% patches of the prints was measured. The prints were then exposed in an Atlas weatherometer to artificial daylight for a total of 240 hours. The density of the patches was measured after 120 hours and again after 240 hours, and the fading of the dyes determined by calculating the percentage density loss on exposure. The results are shown in table 7.

] 5 Table 7

Density loss 120 hours Density loss 240 hours Coating A Coating C Coating A Coating C Cyan 6 4 6 2 11 4 11 1 Magenta 5 4 6 8 12 6 16 0 Yellow 62 54 109 96 Black 86 74 166 167 Red 7 8 10 4 17 8 21 0 Green 8 7 5 6 13 1 9 3 Blue 10-0 3 19-0 18 1 It is seen that there is no major difference between the rates of dye fading on the two inventive media, both these results are acceptable in practice for light stability of images printed with dyed inks.

Example 3

Inventive coatings D, E, and F were prepared using the coating formulation given in table coated on the art paper substrate except that different PVAA copolymer samples as shown in Table 8 were used and the pH of the formulation was adjusted to 6 1 with acid before coating. The coatings were printed with pigmented inks as in example 1 and the colour gamut of the prints determined as in example 1. The calculated gamut value is also

given in table 8.

Table

PVAA copolymer Reference Amine content Cation content MW Gamut D 13 4 mol% 3 18 meq/g 1 12 x 105 10638 E 22 1 mol% 5 24 meq/g 1 24 x 105 10630 F 20 3 mol% 4 81 meq/g 1 29 x 105 10826 ] O It is seen that these inventive samples all achieve excellent colour gamut.

Claims

Claims 1. A recording material suitable for ink jet recording comprising

a sheet like substrate and arranged on at least one side of the substrate at least one ink-receptive recording layer comprising: À silica; and À a water receptive polymeric binder comprising gelatin and at least one cationic polyvinyl alcohol derivative; wherein the ratio of the dry coating weight of the silica to the total dry coating weight of the binder is between 5:1 and 1 3:1.
2. A recording material according to claim I wherein the substrate is a fine art paper or canvas.
3. A recording material according to claim 2 wherein the ratio of the dry coating weight of the silica to the total dry coating weight of the binder is between 1 5:1 and 1 3:1.
4. A recording material according to any of claims I - 3 wherein the silica is an amorphous synthetic fine particulate silica of average particle size between I lam and 25,um.
5. A recording material according to any of claims I - 4 wherein the cationic polyvinyl alcohol derivative is a polyvinyl alcohol/ polyvinylamine copolymer.
6. A recording material according to claim 5 wherein the polyvinyl alcohol/ polyvinylamine copolymer is characterised by an average molecular weight in the range of 10,000 to 170,000; and the proportion of vinylamine in the copolymer is between 10 and 20 mole %.
7. A recording material according to either of claims 5 or 6 wherein the polyvinyl alcohol/ polyvinylamine copolymer is prepared by polymerization of a combination of vinyl acetate with an N-vinyl amide and subsequent hydrolysis of the acetate and amide groups on the polymer.
8. A recording material according to any of claims 1 - 7 which also comprises a suri:actant.
9. A recording material according to any of the preceding claims wherein the total dry coating weight of the ink-receptive layer is in the range of 5 am-2 to SO gm-2.
10. An ink jet recording method comprising the steps of ejecting droplets of an aqueous ink composition comprising at least a colorant and a carrier liquid onto a recording material according to any of claims I - 9 to deposit the ink droplets onto the recording material in an imagewise pattern, thereby generating images on the recording material.