GB2410705A - Inkjet recording material and method - Google Patents

Abstract

An inkjet recording material comprises a substrate coated with an ink receiving composition. The substrate may be non absorbent eg. cellulose acetate, polyethylene, polypropylene, PVC, polycarbonate, polyester or a resin coated or barrier coated paper. The ink receiving composition comprises silica (synthetic, ca. 50 micron), a water soluble acrylate (acrylic, methacrylic or maleic acid polymers or copolymers, especially styrene or acrylate ester copolymers) and a basic polymer (polyamine, polyimine and especially a vinyl imidazole / vinyl pyrrolidone copolymer). The composition may also include surfactants, antifoams, optical brighteners, UV stabilisers and other additives. The substrate may be treated eg. by corona discharge or by application of a primer layer, to improve adhesion of the coating. The primer layer may comprise an acrylic modified polyurethane, cross-linked with a polymeric aziridine. In use the recording material may be printed upon, left to dry and then laminated to a transparent protective film.

Description

24 1 0705 Recordine Material and Method

Field of the Invention

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

Backaround 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. There are several classes of ink jet printer, for instance thermal drop-on-demand printers, piezo drop-ondemand printers, and continuous ink jet printers. Ink jet recording has undergone intensive development in recent years, and has found broad application as output for personal computers in the office and the home because of its accessible price, low noise characteristic, capability of high speed printing, facility of multi-colour printing, reliability, ] 5 and achievable image quality.

Inks for ink jet printers generally comprise; a colorant, which may be a dye or a pigment; and a carrier liquid, which typically is made up mainly of water, together with at least one water miscible organic cosolvent such as a polyhydric alcohol. 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. Frequently the ink also comprises other addenda such as one or more surfactants.

Increasingly severe requirements are being set for recording materials for the ink jet process. The recording produced by means of an ink jet processes is required to have, for example, good water and smear resistance, high resolution, high colour density, sufficient ink gradation, and good light fastness. Furthermore the material must be robust and resistant to mechanical damage such as cracking. An additional feature of particular interest is compatibility of the recording material with both dyed and pigmented inks printed with a wide variety of printers.

It has become common to provide ink jet recording materials comprising at least one ink-receptive recording layer arranged on a suitable substrate. In general, two types of recording layer are in use in such systems: socalled swelling polymer types and so-called porous types. For many applications the porous types are preferred because prints on such materials are quickly dry to the touch after printing as the liquid phase of the ink absorbs very rapidly into the pores. Such materials also provide excellent image quality.

Typically, the image receiving layer of a porous type recording system comprises fine particles of one or more colourless absorbent filler or pigment in combination with a water-accepting polymeric binder, optionally also in combination with an additive such as a cationic compound in order to bind the dyes from the inks. For instance United States Patent 5,213,873 describes a combination of silica particles with polyvinyl alcohol and cationic water soluble acrylic polymers.

A problem which may arise when such materials are printed with pigmented inks is that the pigment from the ink remains on the surface of the image and the print may be susceptible to surface damage such as scratching and smudging when handled. On the other hand, when dyed aqueous inks are used the printed image may be sensitive to water, and the fastness towards light and atmospheric gases is insufficient for many applications involving outdoor exposure.

One way of overcoming these disadvantages is provided by our European Patent Applications l 078 775 A and 1 188 574 A which provide recording materials comprising an ink receiving layer and an upper sealing layer. After printing, the upper layer is sealed by the application of heat to provide a robust image-protecting layer.

Another way of improving the robustness of ink jet printed images, particularly those intended for outdoor display, is to laminate the printed image. By lamination is meant the combination of a printed ink jet receiving layer with a protective transparent overlay, this combination usually being accomplished with an adhesive activated by heat, pressure, or both. The overlay acts as a physical protection for the image, seals it from ingress of water and atmospheric pollutants, improves resistance against kinks and the like, and may also incorporate one or more light stabilisers such as a UV absorber.

Laminates do not always adhere well to printed ink jet images. In particular, with porous type recording materials cohesion of the layer may be insufficient to prevent a tendency for the adhesive of the laminate to pick off particles of the pigment or filler of the ink receiving layer rather than to adhere to the layer. This tendency may be reduced by increasing the proportion of binder to pigment in the layer. On the other hand, it is normally preferred to minimise the proportion of binder in the layer to increase the speed of absorption of the ink and the quantity of ink which may be absorbed.

Thus there is still a requirement for an improved image receiving material which is compatible with both dyed and pigmented inks, rapid to dry, provides good image quality, and which is robust to lamination. 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 on at least one side of the substrate at least one ink-receptive recording layer comprising in combination: 1) silica; 2) a water soluble polymeric acrylate binder; and 3) a basic polymer.

Detailed Description of the Invention

Suitable substrates for the recording materials of the invention include any substrate commonly used for printing and imaging media, especially non-absorbent substrates such as resin-coated or barrier-coated paper, cellulose acetates, polyethylene, polypropylene, polyvinyl chloride, polycarbonate, and polyesters including polyethylene terephthalate and polyethylene naphthalate. A particularly preferable substrate is rigid opaque polyvinyl chloride. Another particularly preferable substrate is biaxially oriented polypropylene.

Other preferred substrates are resin-coated paper such as polyethylene coated paper and barrier-coated paper.

The substrate thickness is not particularly restricted, but may be up to 500 m, especially between approximately 100 Em and approximately 400 1lm for many display applications.

By a barrier-coated paper is meant a porous paper whose surface has been coated with a coherent barrier layer designed to prevent penetration of a material into the paper. Such papers are commercially well known as supports for imaging materials but are also in widespread use elsewhere, particularly in the packaging and food industries. The chemical composition of the barrier layer is selected according to the type of material against which protection is sought, and typically may comprise a film-forming latex polymer such as a polyacrylate or a styrene/ butadiene latex, optionally in combination with one or more inorganic pigment or filler. There may also be present a primer layer comprising a white pigment or filler to improve the smoothness, whiteness, and opacity of the substrate.

l O The substrate may contain other additives as are known in the art. Additives suitable for the preferred polyvinyl chloride and polypropylene substrates include in particular opacifying white fillers or pigments and optical brightening agents.

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

By water soluble acrylate polymer binder is meant a water soluble matrix forming polymer comprising ethylenically unsaturated monomers such as acrylic, methacrylic, or maleic acids, together optionally with additional comonomers such as acrylate esters or styrene.

Many suitable acrylate polymers having various monomer ratios and molecular weights are commercially available. Such acrylate polymers may be supplied commercially in the form of concentrated solutions in aqueous base, or may be supplied as solids which are to be dissolved in water in the presence of a base. Suitable bases for neutralising such polymers include sodium or potassium hydroxide, ammonia, or an organic amine base. The acrylate polymer may be further characterized by a Tg of between 25 C and 100 C, preferably between approximately 40 C and approximately 50 C.

By basic polymer is meant a polymeric organic substance having basic properties, usually by comprising one or more nitrogen atoms in the molecular structure. When present in the material of the invention such a polymer may carry positive charge and may complex or mordant anionic components in an ink. Suitable basic polymers include polyethyleneimine and polymers and copolymers comprising monomers such as vinyl pyridine, vinyl imidazole, and amine containing acrylates or methacrylates. Such basic polymers are known. A particularly preferred basic polymer is a copolymer of vinyl imidazole and vinyl pyrrolidone.

It is in general necessary that one or more surfactants be present in the coating formulation to allow for smooth coating and evenness of the layer and to improve printing properties.

The surfactant used is not particularly limited as long as it is compatible with the other components of the assembly. 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 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; N-acyl-N-alkyltaurines, alkylnaphthalenesulphonates, alkylbenzenesulphonates, alkyl sulphonates, or dialkyl sulphosuccinates. Further, silicone surfactants such as polyether modified polydimethylsiloxane are also suitable. Mixtures of two or more of the above mentioned surfactants may also be used. Such surfactants are well known in the art.

It is preferred that one or more cross linking agents for the polymer binders also be present.

Crosslinking allows for the modification of the physical properties of the layers, in particular in robustness and in resistance against physical damage especially when wet.

Suitable cross linking agents may be any of those known in the art, including especially epoxy and aziridine cross linking agents and mixtures of two or more of such crosslinking agents.

The pH of the coating formulation may be between 3 and 10, and preferably the pH is in the range 7 to 9. The pH may be controlled by appropriate choice of the acrylate and basic polymer components and by the quantity of alkali used to dissolve the acrylate polymer.

Further, the pH may be adjusted if necessary by addition of acid or alkali. Additionally, pH buffers may be present. At the preferred somewhat alkaline pH values it is believed that the preferred vinyl imidazole/ vinyl pyrrolidone basic copolymer is partially protonated on the basic nitrogen atoms.

In addition to the components already mentioned, the ink-receptive layer or layers may advantageously also contain further auxiliary agents as are known in the art, for example plasticisers, lubricants, latexes, antistatic agents, fungicides, dispersants, antifoams, ultraviolet absorbers, and optical brighteners.

The coated amount of the recording layer may be determined mainly according to the quantity of ink laid down by the printing apparatus in use, but also according to the substrate and the components used. If the coating weight is too low the ink absorptivity of the recording layer is insufficient and the material is slow to dry, also leading to image problems such as puddling and blurring. A suitable total dry coating weight of the ink-receptive layer is from approximately 5 am-2 to approximately 50 gm-2, preferably from approximately to am-2 to approximately 25 gm-2, and most preferably from approximately am-2 to approximately 25 gm-2. If insufficient binder is present the coated layer becomes fragile and powdery. Therefore the minimum ratio of silica to the total polymer content of the layer is approximately 1:1 by weight, but a preferred ratio is approximately 3:4 lor applications involving overlamination. The ratio of the polymeric acrylate binder to the basic polymer may vary between approximately 1:1 and approximately 3:1, preferably approximately 2:1 by weight.

It may be advantageous to treat the front surface of the substrate to assist adhesion of the image receiving layer. This treatment may take the form of at least one of: a surface modification technique such as flame treatment, corona treatment, buffing, or the like; and the application of an adhesion-promoting chemical priming or subbing layer. Such adhesion promoting treatments are well known.

In one preferred embodiment of the invention, the substrate is polypropylene and the adhesion-promoting treatment consists of a corona discharge.

In another preferred embodiment of the invention, the adhesion-promoting treatment consists of a chemical priming layer comprising a combination of an acrylic modified polyurethane dispersion and an aziridine cross linker.

Therefore according to this preferred embodiment of the invention there is provided a recording material suitable for ink jet recording comprising in the following order: a sheet like substrate, at least one adhesion promoting layer comprising: 1) an acrylic modified polyurethane dispersion; and 2) a polymeric aziridine cross linker; and at least one ink-receptive layer comprising: 1) silica; 2) a water-soluble polymeric acrylate binder; and 3) a basic polymer; wherein the substrate, silica, polymeric acrylate binder, and basic polymer are as hereinbefore defined. It is especially preferred in this embodiment that the substrate is polyvinyl chloride.

The acrylic modified polyurethane dispersion and aziridine cross linker components of the adhesion-promoting layer are known in the art for this use and suitable components are commercially available. A suitable total dry coating weight for the adhesion promoting layer is up to approximately 5 gm-2, preferably from about 2 5 am-2 to about 5 gm-2.

One of the advantages of the recording materials of the present invention is that the ink-receptive layer and the adhesion promoting layer may conveniently be produced as aqueous formulations and coated on to the substrate by any suitable coating means, such as a slide bead coaler, a curtain coaler, a rod coaler, a gravure coaler, a doctor blade coaler, an air knife coaler, a dip coaler, a smooth roll coaler, a reverse roll coaler, or a bar coaler. The ink-receptive layer and adhesion promoting layer may be coated one after the other or simultaneously. Some of the above listed coating methods allow for simultaneous coatings of two or more layers, which is preferred from a manufacturing economic perspective.

It is in general necessary that one or more surfactants be present in the coating formulation of the adhesion promoting layer. Examples of suitable surfactants are as hereinbefore described, but silicone surfactants such as polyether modified polydimethylsiloxane are especially preferred.

The back surface of the substrate may be left uncoated or may be treated for antistatic properties or to promote transport in the printing apparatus.

The materials of the invention are suitable as ink jet receiving materials for use with a variety of ink jet printers, 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 ]O jet printer or a wide format ink jet printer. The materials are suitable for use with inks comprising dyes or pigments as colorants. 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 cosolvents such as a polyhydric alcohol. Frequently the ink also comprises one or more surfactant. Such inks are well known in the art.

The materials of the present invention are particularly suitable for applications wherein the printed image is to be protected by lamination. According to this aspect of the invention, there is provided an ink jet recording method comprising the steps of: 1) ejecting droplets of an ink composition comprising at least a colorant and a carrier liquid onto the recording medium of the present invention by means of an ink jet printer to deposit the ink droplets onto the recording medium in an imagewise pattern, thereby generating images on the material; 2) drying the printed image; and 3) laminating the printed image with a transparent protective covering film attached to the printed surface of the image receiving layer with an adhesive activated by heat, pressure, or both.

The ink jet printer may be any known 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.

The colorant of the ink composition may be any colorant as is known for use in ink jet ink compositions, such as a dye, a pigment, or a coloured resin particle. By the term dye is meant a colorant which is present as a solution in the ink. Any suitable dye may be used, but anionic dyes such as acid dyes and direct dyes are commonly used in aqueous inks. By the term pigment is meant a colorant which is provided in an insoluble particulate state.

Suitable pigments include so-called self dispersing pigments and conventional pigments which are stabilised by the presence of one or more dispersants. Suitable colorants for ink jet inks are well known. It is of course possible to use more than one colorant in the ink.

Typically, in most commercial ink jet printers a set of four inks is provided comprising the three subtractive primary colours cyan, magenta, and yellow, together with a black ink. It is also known to use ink sets comprising additional inks, for example additional dilute ("light") inks such as dilute cyan and magenta inks or inks of additional colours such red, blue, orange, violet, or green inks.

The carrier liquid may be any fluid vehicle as known in ink jet inks, but preferably the carrier liquid is an aqueous liquid, that is to say it comprises predominantly water, but may also comprise one or more water soluble organic cosolvents. Deionised water is commonly used. The carrier liquid may consist solely of water, but preferably the fluid vehicle is a mixture comprising water and at least one relatively involatile water miscible organic cosolvent such as a polyhydric alcohol. The water miscible organic cosolvent may be any organic solvent having sufficient solubility in water. Commonly a combination of two or more cosolvents is used. The total proportion of the organic cosolvent component(s) may be up to approximately 50% by weight of the ink, preferably up to approximately 25% by weight. The organic solvent component(s) generally serve as humectant to prevent drying out of the ink in the nozzles of the printer, but may also serve as cosolvent, viscosity regulating agent, ink penetration additive, wetting agent, levelling agent or drying agent.

The ink may also comprise other components that are advantageously added to aqueous ink jet inks, such as surfactants, viscosity modifiers, and biocides. In addition, sequestering agents such as EDTA may also be included to eliminate deleterious effects of heavy metal impurities. Such aqueous ink jet inks are well known in the art and are supplied for use with many commercially available ink jet printers.

A drying time of at least 30 minutes is necessary to allow sufficient carrier liquid of the ink to evaporate as described on page 187 of the proceedings of IS&T NIP17 International Conference on Digital Printing Technologies, 2001. Preferably the drying time is at least 8 hours, and more preferably overnight in ambient room atmosphere with some ventilation, optionally with air flow assisted by a fan. If the print is insufficiently dry before lamination image stability is impaired, particularly with dyed inks because of dye-diffusion and impaired light stability: also adhesion of the laminate may be poor giving visible marks and in the extreme, delamination of the covering film.

The transparent covering film may be any film as known for use in laminating applications, for example a film comprising polyvinyl chloride, polypropylene, polyester such as polyethylene terephthalate, polyurethane, polyacrylate, and the like. Polyvinyl chloride is preferred, and a combination of a polyvinyl chloride substrate for the printed layer and a polyvinyl chloride laminating film is especially preferred. The thickness of the laminating film may be up to approximately 500 Em, especially between approximately 100 lam and approximately 400 sum.

The transparent covering film may be adhered to the image surface of the recording material using any suitable adhesive such as a solvent type acrylic copolymer, an aqueous type acrylic copolymer, or a polyethylene copolymer. A pressure-sensitive cold laminating solvent type acrylic adhesive is preferred. Suitable laminating films comprising both the film and the adhesive are well known and commercially available. The laminate or adhesive may also incorporate one or more light stabilisers such as a UV absorber to improve stability of dyed images. It is possible to encapsulate the materials of the invention, that is to say to adhere a transparent covering film on both the front and back surfaces of the printed material, but this is not preferred.

Preferably, the printed image and covering film are combinedly adhered by passing through a laminator. By laminator is meant a device which is normally used for the lamination of printed images which comprises a means of pressing together the image and the covering film, commonly by passing them through a nip between a pair of rollers. Optionally, the rollers may be heated, but cold lamination is preferred in the practice of the invention.

Suitable laminators are known and in wide commercial use.

The materials and method of this aspect of the invention are particularly useful for so-called roll-up, pull-up, and pop-up displays and also for applications such as banners, pennants and the like. For pop-up displays, the final assembly, that is to say the combination of the substrate, the adhesion promoting layer if present, the ink- receptive layer, the adhesive, and the laminating film, should be sufficiently rigid to remain flat while on display, but sul'ficiently flexible to be rolled up for transport and storage. 'l'hus it is preferred that that the total combined thickness of the assembly is no more than 500 m.

Although the recording materials and method disclosed herein have been referred to primarily as being useful for ink jet printers, they may also be used as media for other recording devices such as pen plotter assemblies. The following examples will serve to illustrate the invention.

Example I

A material according to the invention was prepared as follows. A coating solution for an adhesion promoting layer was formulated using the following components: Component Quantity Acrylic modified polyurethane dispersion 900g Aziridine cross linker 4g Siloxane surfactant 2g Water 90g The polyurethane dispersion was from Zeneca as a 40% aqueous dispersion under the trade name Neorez R973 and the cross linker from Zeneca under the trade name CXIOO. The surfactant was a commercial polyether modified polydimethylsiloxane from BYK-Chemie under the trade name BYKRTM 348.

A coating solution for the image receptive layer was formulated comprising the following components: Component % by weight Synthetic silica 8 66 Polymeric acrylate binder 7 70 Basic polymer 3 84 Siloxane surfactant 0 10 Additional surfactant 0 50 Water remainder The synthetic silica was a micronised porous fine particulate silica of average particle size 12 Em and pore volume 2 ml/g available from GRACE Davison under the trade name SylojetRTM P412. The polymeric acrylate binder was an acrylate polymer having a Tg of 48 C available commercially as a 25% aqueous solution neutralised with an organic base S under the trade name Worleecryl 8025. The basic polymer is a 20% aqueous solution of a 50:50 vinyl imidazole/ vinyl pyrrolidone copolymer from BASF under the trade name Luvitec VPI55K72W. The siloxane surfactant was as used in the adhesion layer, and the additional surfactant was an octyl phenol ethoxylate surfactant available under the trade name TritonRTM X-100.

In the above formulation, the ratio of the polymeric acrylate binder to the basic polymer is 2:1 and the ratio of pigment to the total polymer content of the formulation is 0 75:1. The total solid concentration of the formulation was 20 8%. An addition of 0 5g of a 0 5% solution of an optical brightening agent was then added to the formulation.

The two formulations were coated sequentially on to a support comprising a rigid white opacified calendered polyvinyl chloride substrate of thickness 350,um to give a dry coating weight of 3 am-2 for the adhesion- promoting layer and of approximately 21 am-2 for the image receptive layer. It is believed that the aziridine crosslinker in the formulation of the adhesion-promoting layer also partially crosslinks the binder of the image receiving layer.

A test image was printed on the material using dyed aqueous inks in an HP 5500 ink jet printer. The material printed well to give a good quality image. The material also printed well with an Epson 9600 printer using Ultrachrome pigmented aqueous inks and with ILFORD Archiva Extreme pigmented aqueous inks on Encad Novajet 3, Pro-50, and 42E printers. This shows the compatibility of the inventive material for usc with a variety of printers and ink types.

The image printed with the HP 5500 printer was laminated with a 100 m thick commercially available transparent polyvinyl chloride cold laminating protective covering film with a pressure-sensitive solvent type acrylic adhesive using a laminator. The laminate adhered well and the resultant print was sufficiently rigid for use in pop-up displays and was robust to handling, scratch and scuff resistant, and resistant to delamination.

Example 2

A material according to the invention was prepared by coating the adhesion-promoting and image-receptive layers of example 1 on a 150 Em thick biaxially oriented polypropylene substrate which included white opacifying pigments and an optical brightening agent.

Test images were printed on the material with an HP 7350 ink jet printer using dyed aqueous inks, with an Epson 2100 printer using pigmented aqueous inks, with an Epson 870 printer using dyed aqueous inks, and with an HP 970 printer and dyed aqueous inks.

The material printed well to give good quality images. This shows the compatibility of the inventive material for use with a variety of printers and ink types.

Example 3

A material according to the invention was prepared by coating the adhesion-promoting and image-receptive layers as in example 1 on to a barrier-layer coated paper substrate of total thickness 145 Em and weight 170 am-2 comprising a conventional bond paper base, a hydrophobic barrierlayer, and a pigment filled primer layer.

Further, adhesion of the coating to the substrate was tested as follows: A sticky tab was adhered to the sample and then pulled off at an angle of 180 using a quick, smooth motion. Adhesion was assessed visually by looking at the area where the tab had been pulled off the print for any surface damage or loss of material. No change was seen in the coating after this test and thus adhesion of the coating to the base and cohesion of the coating were both assessed as excellent.

Test images were printed on the material with an Epson 2100 printer using pigmented aqueous inks, with an Epson 870 printer using dyed aqueous inks, and with an HP 970 printer and dyed aqueous inks. The material printed well to give good quality images. This shows the compatibility of the inventive material for use with a variety of printers and ink types.

Claims (11)

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

   a sheet like substrate and on at least one side of the substrate at least one ink- receptive recording layer comprising in combination: 1) silica; 2) a water-soluble polymeric acrylate binder; and 3) a basic polymer.
2. 2. A recording material according to claim I wherein the front surface of the substrate has been treated to assist adhesion of the image receiving layer by at least one of: 1) a surface modification technique selected from: flame treatment, corona treatment, and buffing; and 2) the application of an adhesion-promoting chemical priming layer.
3. 3. A recording material according to claim 2 wherein the adhesionpromoting chemical priming layer comprises: 1) an acrylic modified polyurethane dispersion; and 2) a polymeric aziridine cross linker.
4. 4. A recording material according to any of claims I - 3 wherein the silica is porous synthetic amorphous silica of average particle size in the range of I Em to 25 m.
5. 5. A recording material according to any of claims 1- 4 wherein the acrylate polymer binder is a water soluble matrix forming copolymer comprising at least one monomer selected from acrylic acid, methacrylic acid, and maleic acid.
6. 6. A recording material according to any of claims 1- 5 wherein the basic polymer comprises a copolymer of vinyl imidazole and vinyl pyrrolidone.
7. 7. A recording material according to claims 5 and 6 wherein the weight ratio of the polymeric acrylate binder to the basic polymer is in the range I: I to 3:1.
8. 8. A recording material according to any of claims 1 - 7 wherein the substrate is selected from rigid polyvinyl chloride, biaxially oriented polypropylene, barrier-coated paper, and polyethylene coated paper.
9. 9. An ink jet recording method comprising the steps of 1) ejecting droplets of an ink composition comprising at least a colorant and a carrier liquid onto a recording medium of any of the preceding claims to deposit the ink droplets onto the recording medium in an imagewise pattern, thereby generating images on the material; 2) drying the printed image, and 3) laminating the printed image with a transparent protective covering film attached to the printed surface of the image receiving layer with an adhesive activated by heat, pressure, or both.
10. 10. A recording method according to claim 9 wherein the protective laminating film comprises a polyvinyl chloride film.
11. 11. A recording method according to either claim 9 or 10 wherein the printed image and covering film are adhered by passing through a laminator.