WO2000041891A1

WO2000041891A1 - Printable laminate

Info

Publication number: WO2000041891A1
Application number: PCT/GB2000/000085
Authority: WO
Inventors: Colin J. Cook; Hazel A. Warden
Original assignee: Hunt Graphics Europe Ltd.
Priority date: 1999-01-15
Filing date: 2000-01-13
Publication date: 2000-07-20
Also published as: EP1144196A1; JP2003534144A; KR20010112242A; CN1340005A; AU1994500A; CN1139497C; TW524758B

Abstract

A printable laminate film having improved resistance to delamination or separation of the layers of the laminate. In one embodiment the invention concerns the use of new ink absorber materials and new adhesive materials in an ink recording layer on a carrier film. In another embodiment of the invention, the invention relates to an adhesive layer disposed between the heat recording layer and the carrier film substrate. The invention also concerns a method for selecting the combination of adhesive and ink absorber material in the ink recording layer to improve the resistance of the material to delamination or separation of layers.

Description

PRINTABLE LAMINATE

The present invention relates to the transfer of a printed image onto a target substrate, especially poster board, foam board, or rigid PVC.

A wide variety of techniques have been developed for digitally capturing an image in the form of a computer-readable file, editing the image with a computer, printing the edited image onto a recording medium, and then transferring the image from the recording medium to a target substrate. A target substrate can be one of any number of materials including fabrics , ceramic materials , posterboard, rigid PVC, or mounting board such as, foam board or expanded PVC board which are widely used in the graphic art industry.

The typical recording medium for receiving and transferring an image formed by an ink- jet printer has a carrier and at least two of the following layers : a release layer, a protective barrier layer, image transfer layer, and an adhesive layer. The International Application PCT/GB98/00481 filed February iβ, 1998 for "TRANSFER FILM" describes a carrier having a transfer film which has only one layer. This single layer is a mixture of heat-activatable adhesive particles and a binder that also is ink-absorbing, thereby defining a porous matrix. When used for commercial graphics applications, such a transfer film can be adhered to the target substrate without removing the carrier, whereby the carrier remains affixed to the layer holding the printed image, thereby providing physical protection for the image. U.S. Patent Application 09/107,302 filed June 20, 1998 for "PRINTABLE LAMINATE" (the disclosure of which is incorporated herein by reference), describes a printable laminate material for transferring an image produced by an ink jet printer to a target substrate. The printable laminate has a carrier film on one side of which is disposed an image recording layer comprising an ink absorber and a heat activatable adhesive. The ink absorber is a modified cellulose material, though a cellulose gum or a single cationically charged water- soluble polymer may alsc be used. The heat activatable adhesive is a polyurethan . In the "302 application the polyurethane of the image recording layer is in the form of small strand- like structures which are distributed throughout the i k absorber thereby forming an homogenous mixture with the ink absorber of the recording layer.

U.S. Patent: 5,501,902 describes a multi-layer printable transfer material which can be sealed at 177^GC using a smoothing iron. However, this temperature is far too high for use with mounting boards commonly found in the graphic arts industry. Furthermore, the ~902 Patent describes the use of a powdered polymer with a particle size of up tc 2 ^m. The large particle size tends to produce a printed image having a grainy appearance with a consequent loss of clarity, contrast and brilliance of the printed image.

International Patent Application WO 98/02314 describes a printable transfer material that releases from a temporary carrier, wherein the transferred image is waterproof . This material uses a porous matrix of large particles of a typical size of 20^m. The transfer material is subjected tc a high temperature (typically 190 "O to form a film of polymer which encapsulates the ink inside the film. The inventions disclosed in International Application PCT/GB98/00481 and U.S. Patent Application 09/107,302 have been further investigated, particularly regarding the ability of the printable laminate to resist the separation or delamination of the carrier film from the image recording layer. It was found that cutting or cropping of the printable laminate to obtain a proper size image for display or to obtain a mounted image having an irregular outline as found in some commercial advertising displays often causes the protective carrier layer :o separate from the recording layer .

Separation of the carrier film under these circumstances appears to be due to shear, tension and compression forces exerted by the cutting blade during the cutting process. The forces build as the blade is drawn across and through the printable laminate and when the forces imposed in cutting the material are sufficient to overcome the adhesive yield point of the image transfer layer, the adhesive bond between the image recording layer and the carrier layer fails.

Upon failure, the carrier film separates from the image recording layer and the protection offered by the carrier layer is lost. Moreover, separation cf the carrier layer can greatly detract from the quality of the printed image in that the separation may cause a "silvering" effect which may obscure the image or otherwise detract from the appearance cf the image.

The present invention may provide a printable laminate material with improved resistance to delamination cf the carrier film from the image recording layer through the use of new heat activated adhesives, new ink absorbers, and combinations thereof in the recording layer. The printable laminate material may have improved resistance tc delamination of the carrier film provided by a layer of polymeric material having desirable viscoeiastic properties in the structure cf the printable laminate.

According to the present invention in a first aspect there is provided a printable laminate comprising a carrier film which is substantially transparent, and an image recording layer which is disposed en the carrier film. The image recording layer comprises a heat activated adhesive and an ink absorber. The heat activatable adhesive is one or more adhesive materials such as poiyurethanes , vinyl ester copolymers, acrylics, and icnomers formed from various salts of oiefir.s and unsat rated acid copolymers. The adhesives are most preferable those which are available in the form of aqueous dispersions . The ink absorber is one cr more ink absorber materials such as blends of cationic polymers, blends of cationic polymers and cellulose either, and polyvinyl alcohol. The new adhesives and combinations of adhesives and ink absorbers produce an ink recording layer with a higher yield point, making the laminate less susceptible to delamination.

According to a variation of tne first aspect, the printable laminate comprises a substantially transparent carrier film having opposite first and second sides; a substantially uniform thermoplastic image recording layer having an inner surface directly supported by one side of the carrier film and an exposed outer surface for receiving printed ink; where a first, thermoplastic, heat activated adhesive material constitutes about 40 - 65 weight percent cf the recording layer, and at least 75 per cent cf the remaining weight of the recording layer is constituted by a different, ink absorbing, tnermooiastic , cationic polymer material. According to the invention in a second aspect, there is provided a patentable laminate comprising a carrier film which is substantially transparent, a layer of viscoeiastic material disposed on the carrier film, and an image recording layer disposed on the layer of viscoeiastic material. The viscoeiastic material is one or more thermoplastic polymers such as polyurethanes , acrylics, vinyls, butadiene-styrene copolymers, i s opren - s tyrene copolymers, polychloroprenes , and olefinic polymers having physical properties which contribute to the "damping" of shearing forces imposed by a blade cutting the laminate. The image recording layer includes an ink absorber which may be one or more blends of cationic polymers, blends of cationic polymers and cellulose ether, and polyvinyi alcohol, along with a heat activatable adhesive which may include one or more materials such as polyurethanes, vinyl ester copolymers, acrylic ester copolymers, and ionomers as previously described in reference to the heat activatable adhesives such as polyurethanes, phenoxy resins, acrylics, vinyls, butadiene-styrene copolymers, i soprene - styrene copolymers, polychloroprenes, and olefinic polymers, which may be the same or different than the viscoeiastic materials as described herein above. The ink absorber in the image recording layer is the same as described in reference to the ink absorber cf the first embodiment, namely one or more ink absorber materials such as blends of cationic polymers, blends of cationic polymers and cellulose either, and polyvinyi alcohol.

The invention accordingly comprises the several components and the relation cf one or more cf such components with respect to each cf the others, and the article possession of the features, properties, and relation cf elements exemplified in the following detailed disclosure . Brief Description of the Drawings

Figure 1 shows a cross-sectional representation of an embodiment of the printable laminate of the invention which includes a carrier film, and image recording layer.

a second embodiment cf the printable laminate of the invention which includes a carrier film, a layer of viscoeiastic material and image recording layer.

Figure 3 shows a partial cross-sectional representation of a printable laminate of the invention in the process of being laminated to a target substrate.

Detailed Description of the Invention

In the Figures and in the description which follows it will be appreciated that like figures, structures and features will be identified by the same reference numerals .

Figure 1 shows a printable laminate 10 made according to the first embodiment of the present invention. The printable laminate comprises a substantially transparent carrier film 12 having a first surface and a second surface, and an image recording layer 14 having an inner surface and an outer surface, the inner surface of the image recording layer being directly supported in full and intimate contact on one of the surfaces of the carrier film 12. The exposed outer surface cf the image recording layer is intended for receiving an ink image which typically is applied by means of an ink-jet printer (not shown) . The pattern of ink deposits 16 formed by the ink-jet printer diffuse through the thickness of the recording layer 14 without substantial deσradation. In Figure 2, a printable laminate 20 made according to the second embodiment of the present invention is shown. The printable laminate 20 comprises a carrier film 12 having a first surface and a second surface, a layer of viscoeiastic material 25 likewise having a first surface and a second surface, the viscoeiastic material being directly supported on one of its surfaces in full and intimate contact on one cf surface cf the carrier film, and an image recording layer 14 having an inner surface and an outer surface, the inner surface being directly supported in full and intimate contact with the other surface of the layer of viscoeiastic material. The exposed outer surface of the image recording layer is intended for receiving an image applied by an ink- jet printer (not shown) , wherein the image takes the form cf a pattern of ink deposits 16 as described above in reference to Figure 1.

In Figure 3, the printable laminate 1C made according to the first embodiment of the invention is shown in the process cf being laminated to a mounting board 30. The mounting board shown here is a substantially rigid, planar structure formed from a layer cf expanded polystyrene 32 on at least one side cf which is supported a layer cf paper 34. The paper provides a convenient surface onto which the printable laminate 10 is adhered. The image recording layer 14 of the printable laminate in Figure 3 was imprinted with an image by an ink jet printer prior to lamination, as evidenced by the present of ink deposits 16 in the image recording layer.

The image recording layer is heated by contact of the printable laminate with the heated laminating roller

36 tc a temperature at which the adhesive in the image recording layer is activated. It is envisioned that other means cf heating the image recording layer cf the laminate can be used, including the use of heating elements external to the rollers. The mounting board 30 and printable laminate are brought into intimate contact while the adhesive is active and the combination of heat from the laminating roller 36 and pressure from the pinch roller 38 are sufficient to securely adhere the printable laminate to the mounting board.

It will be understood that no melt transfer cf the image recording layer or release cf the image recording layer from the carrier film is intended m this invention. Rather, the carrier is intended to be retained in place over the image recording layer after the printable laminate has been adhered to the target surface .

The carrier film in the present invention is preferable a clear or substantially clear film having a polymeric composition. Such polymeric film materials suitable for the carrier layer of the invention include polyester, polyvinyi chloride, polyvinyi fluoride, or polypropylene films. In addition, multi-layer carrier films may also be used in this invention, especially when texture on the graphic is desired. One suitable multi-layer film for use m the invention is DEEP CRYSTAL, a laminate of 30um, textured polypropylene film and 50 m polyester film, available from Assi-Doman, Belgium. CRYSTAL MATT is a similar multi-layer carrier film available from the same supplier.

The surface of the selected film may optionally be treated with chemicals and/or by various processes to improve the adhesion of materials to the film. One such treatment is corona discharge treatment . The carrier film used in tne invention typically has a tnickness m the range of 36 tc 250 urn, with a thickness of approximately 50 urn. being preferred.

The recording layer of this embodiment cf the invention comprising a carrier film and an image recording layer comprises a heat activated adhesive and an mk-absorper . The heat activated adhesive fcr use m this em odiment of tne invention is one or more adhesives selected from the group consisting cf polyurethanes, vinyl ester copolymers, acrylic ester copolymers, and cnomeric copolymers. The ιn apsorpers for use m this emoodiment of the present invention include one or mere materials selected from the group consisting of plends cf cationic polymers, clends cf cationic polymers and cellulose etner, and polyvinyi alcohols .

The polyurethanes fcr use m this invention are exemplified by tne materials commercially available as LUPHEN-D available m the grades DS 3507, DS 3459, 200A from BASF Corp. , Cheadle, Cheshire, UK; WITCOBOND grades 233-22, 242-6", 280-42 and 755 all available from Baxenden, Droitwicn, Worcestershire, UK; and NEOREZ R- 563 from Zeneca Resins, orthwicn, Chesnire, UK.

Examples cf vinyl ester copolymers suitaoie for use m tne invention include materials wnich are commercially available under tne names CRODALAM 29-188 from Croda Adhesives, Newark Nottmghamsnire , UK, VINNAPAS available in tne grades EP1 , ΞP400, ΞN424, and EF424, and EF41, and VINNOL CE752, all available from Wacker-Chemie , Munich, Germany.

Examples cf suitable acrylic ester copolymers for use m tne present invention include GLASCCL grades LS2C, and C44, from Ciba Specialty Chemicals, Bradford West Yorkshire, UK; and ACRONAL 290D, from BASF.

The ionomeric copolymers suitable fcr use in the present invention are metal, ammonium or amine salts formed fro the copolymers cf olefins and unsaturated acids. The olefins are most typically C - C olefins. The unsaturated acids which are copoivmerized with the olefins to form the acidic copolymers are unsaturated acids including acrylic, methacrylic, crotonic, maleic, and many other suitable acids which are will known in the industry. The suitable materials combined with the copolymers to form a salt include metals, and or other neutralizers such as sodium, potassium, zinc, ammonia, and amines. Examples of the ionomeric copolymers are those materials commercially available under the name AQUASΞAL grades 1086 and 1127, from Paramelt, Heerhugowaard Netherlands; and ADCOTE 37 R220 from Morton International BV, Amersfoort, Netherland.

The cationic polymers for use as absorbers in this invention, in general, are polymers which contain trivalant nitrogen or quaternary nitrogen. The trivalent nitrogen can be present as part of a linear or cyclic structure, in functional groups such as primary secondary or tertiary amines or amino-compounds , polyamines, amides, iactams, pyrrolidones , amine oxides, and aromatic nitrogen rings (heterocyclics) . The quaternary nitrogen compounds are typically formed by reacting tertiary amines with an aikyl or alkylaryl haiide. In principle, any polymer which contains a tertiary nitrogen or ring nitrogen can be converted to a quaternary nitrogen compound. Specific cationic polymers for use in the invention may be selected from the group consisting of vinyl pyrrolidone homopolymer, vinyl pyrroiidone-vinyi ester copolymer, acrylic ester- vinyl pyrrciidone copolymer, acrylic ester-cationic- substituted acrylic monomer copolymer, polyoxazciine , and cationic-substituted acrylic ester-acryiamide copolymer-. The vinyl pyrrolidone homopolymers fcr use in this embodiment of the invention are exemplified by LUVISKOL, grades K30, and K6G, commercially available from BASF; PVP K-60 from International Specialty Products, Guildford, Surrey, UK; and GLASCOL DP6-7132 from Ciba Specialty Chemicals. The vinyl pyrroiidone - vinyl ester copolymer of the invention are exemplified by LUVISKOL VA64, from BASF; PVP/VA S-630, from International Specialty Products; and COLLACRAL VI, from BASF. The acrylic ester copoivmerized with a cationic- substituted acrylic monomer is available under the name GLASCOL grades DP6-2779, and DP6-2724, from Ciba Specialty Chemicals. The copolymer of cationic- substituted acrylic ester and acrylamide is exemplified by the materials commercially available under the name SEDIPUR grades CL 750, and CF 604, from BASF. The polyoxazolines are exemplified by poly (2-ethyl-2- oxazoline) from Sigma Aldrich Company Limited of

Gillingham, Dorset, UK.

Notwithstanding the variety of absorber materials identified above, thermoplastic ink absorbers are preferred. For example another type cf absorber material is modified cellulose material and more preferable a thermoplastic modified cellulose material. Suitable ink absorbers include hydroxypropyl cellulose and cellulose gum. One particularly favored thermoplastic modified cellulose is Klucel E modified cellulose powder, commercially available from Hercules, Wilmington, Delaware. Other suitable materials which are not thermoplastic include Blanose cellulose gum .sodium carbcxymethyiceiiulose) . These can generally be described as cellulose ether. GLASCOL DP6 , mentioned above, is also a suitable but not thermoplastic material . The polyvinyi alcohols for use of this embodiment of the invention are exemplified by the following:

MOWIOL 8-88, ALCOTEX 55-002H, and ALCOTEX SG from Harlow

Chemical Company, Harlow, Essex, UK; and POLYVIOL M05/140, from Wacker-Chemie .

The heat activatable adhesive and ink absorber together comprise 90 - 100% cf the total weight of the image recording layer. Preferabiey, the heat activated adhesive and ink absorber comprise from about 92 to 99% and most preferable, from 97 - 99% of the total weight of the recording layer. The heat activatable adhesive comprises about 33 - 77% pph (parts per hundred weight; and most preferably, about 40 - 65 pph of the total weight of the image recording layer, with at least 75% of the remaining weight of the recording layer constituted by a different, ink absorbing, preferable thermoplastic, cationic polymer material. The ink absorber preferable comprises about 20 - 66 pph, and preferable about 30 - 50 pph of the total weight of the image recording layer. The balance of the image recording layer optionally comprises surfactant and thickener fcr improving handling and application of the image recording layer in making the printable laminate. The image recording layer formed on the carrier film has a thickness which ranges about 10 - 45 .•.m with a preferred thickness of about 26um,

The recording layer in this embodiment cf the invention is applied to the carrier film in the form of an emulsion, preferably a water-based emulsion, and allowed to dry at a temperature below the film forming temperature of the adhesive. Application cf the image recording layer may be carried out by any suitable means, including spreading the image recording material with a doctor blade or other spreading device, drop coating the material, and possibly spraying tne material to form a suitable layer. The structure of the dried film is that cf particles cf adnesive distriouted througnout an essentially continuous layer of the water- soluble ιnκ apsorper. The size of the adhesive particles is m the range of 0.08 - 3.0 urn , with a size of approximately 0.1 urn being preferred. In addition, the adhesive particles have a strand-like conformation.

In an alternate emoodiment of the invention improved resistance to delamination of tne carrier film is provided througn the inclusion of a layer of an extensible viscoeiastic polymeric material incorporated m the structure of the printable laminate. The term "extensible", as used herein, refers to the property of a material to oe stretched or otnerwise distorted by a given force and resist PreaKage . In this emoodiment of the invention therefore comprises a carrier film, a layer of a viscoeiastic material disposed on tne carrier film, and an image recording layer disposed on the layer of viscoeiastic material. The carrier film for use m this embodiment of the invention is the same as described above.

The viscoeiastic material is a thermoplastic polymer witn viscoeiastic physical properties wmch exmpits good adhesion tc tne carrier film and also to the ink aosorbing layer. Desirable properties of the viscoeiastic material include a T iglass transition temperature; of less than room temperature and typically Between -55"C and *10°C. A modulus (storage modulus, or G') of between 5 x 10 and 2 x 10 dyne /cm is desirable. A viscosity (loss modulus) of between 2.2 x 10 and 4 x 10 Poise is preferable. As a general description of tne physical properties cf the viscoeiastic material of the invention, the material is extensible m that it resists breaKage wnen suo^ected to tne force or forces applied m cutting or cropping tne prmtaole laminate. Practitioners skilled in the art will recognize the viscoeiastic material layer of the invention can be used in combination with the printable laminate as described in U.S. Patent Application 09/107/302 and other printable laminates, particularly those in which the carrier layer is retained by the laminate.

The viscoeiastic material may comprise one or more polymers selected from the group consisting of polyurethanes, acrylics, vinyls, butadiene-styrene copolymers, i soprene - s tyrene copolymers, polychloroprenes, and olefinic polymers. In the category of vinyls, ethyiene-vinyl acetate copolymers are found to be especially suitable fcr use in the invention .

Specific examples cf acrylics useful in this embodiment of the invention include those acrylic polymers commercially available under the name DUROTAK from National Starch and Chemical Company, Slough, Berkshire, UK; ACRONAL grades from BASF.

The vinyls suitable for use in the adhesive layer of this invention include: VINNAPAS EP1, available from Wacker Chemie of Munich, Germany.

Butadiene-styrene copolymers suitable for use in the invention are exemplified by REVINEX 80R10 from Doverstrand Ltd., Harlow, Essex, United Kingdom.

Isoprene- styrene copolymers are exemplified by the materials available from Shell Chemicals UK Limited, Chester, UK, under the name KRATON D and KRATON G.

Polychioroprene is commercially available from 3ayer A.G., Dormagen, Germany, under the names DISPΞRCOLL C and BAYPREN . Suitable olefinic polymers include poiyisobutyiene commercially available from BASF, under the name OPPANOL. Other olefinic polymers include polybutadiene and poiyisoprene .

The layer of viscoeiastic material may contain minor amounts of various materials to improve the performance of the printable laminate. These materials include plasticizers to further improve the desired viscoeiastic and extensible properties of the material. In addition, light absorbers may be added tc the viscoeiastic materials tc aid in the filtering cf various segments of the light spectrum which are transmitted through the carrier layer and eventually reach the image in the image recording layer. In particular, ultra-violet light absorber materials can be added to the adhesive layer to remove that part cf the UV spectrum that would tend to degrade the image held in the ink absorbing layer through the actinating effect of sunlight and artificial light.

Suitable plasticizers, such as phthalate esters, are commercially available from Alcohols Ltd., Bishop's Stortford, Hertfordshire, UK; phosphate esters are available from Ciba, Manchester, UK; and chlorinated paraffin is available from IC Chlor- Chemicals , ncorn, Cheshire, UK. Suitable light absorbers are known widely and include such materials sold under the trademark TINUVIN, from Ciba Chemicals, Manchester, UK.

Some of the thermoplastic polymers for use m this embodiment in the invention may be particularly tacky when used at room temperature. Therefore it is envisioned that the carrier film may be treated with a release-coating material on the surface fcr the film opposite the adhesive layer so that the film can be easiiv unwound from a soocl or roll and unwound as needed for use m printing or mounting of tne printable laminate. Sucn release coatings are commonly Known ιr. tne adhesives industry and include such materials as ESCOAT P ' polyvinyi octadecyl caroamate > , commercially available from Emerald Chemicals Ltd, Windsor, Berkshire, UK.

The image recording layer cf tnis empodiment of the invention comprises a heat activatable adnesive and an ink absorper The heat activataple adhesive is one or more materials selected from the group consisting of polyuretnanes , vinyl ester copolymers, acrylic ester copolymers, and ionomeric copolymers, (all as previously ctescriPed m reference to the neat activatable adnesive found m tne image recording layer cf the first empodiment cf tne invention) , polyuretnanes, acrylics, vinyls, putadiene- styrene copolymers, isoprene- styrene copolymers, polychloroprenes, and olefinic polymers (all as previously described m reference to tne viscoeiastic material as described above in reference to tne present embodiment of the invention) and phenoxy resins. The ink absorbers for use m the present empodiment are selected from tne group consisting of blends of cationic polymers, blends of cationic polymers and cellulose ether, ana pc-yvinyl alconol, all as previously αescrioed m reference to the ιnκ aosorper of tne first embodiment cf tne present invention) .

The phenoxy resin suitable for use as a heat activatable adnesive m the recording layer cf the invention s exemplified by the resin commercially available under the name PKHW-35, from Phenoxy Associates, ROCK: Hill, South Carolina. When a phenoxy resin is used m the image recording layer it may be necessary tc use an amphoteric surfactant m comomation witn the pnenoxy resin to act as a cr.arge reverser Normally, the pnenoxy resin us suppiieα _n tne form cr an anionic dispersion m water and anionic dispersions are not normally ccmpatioie with cationic polymers ' such as ink aPsorpers wnicn may be used m tne image recording layer, Therefore, the practitioner will appreciate tne need fcr reαucmg tne negative cnarge of tne pnenoxy resin tnrougn the use of an ampnoteπc surfactant. The ampnoteric surfactant acts as a "briαge" oetween tne anionic phenoxy resin and the cationic polymers m tne image recording layer. It will be appreciated tnat tne utility of ampnoteric surfactants extends oeyond the use m systems using phenoxy resins. In fact, any anionic adhesive used in connection with this invention may have its compatibility witn cationic ink apsorPers improved tnougn tne use of ampnoteric surfactants. An example of a suitable ampnoteric surfactant s CRODATERIC CYNA, from Croαa Surfactants Ltd., Snaitn, Humbersiαe, UK.

The viscoeiastic material may be deposited directly onto the carrier film m the form of an aqueous dispersion, a solution formed with an organic solvent, or -_n tne form of a hot melt. Typically, the viscoeiastic material layer comprises 60 - 80% by weight of tne viscoeiastic material layer and tne image recording layer ccmpined. Preferaoly, tne viscoeiastic material comprises 62.5 - 80.0% and most preferaoly, 70. C - 75.0% of tne comDined amount of tne viscoeiastic material layer and tne image recording layer.

Within tne viscoeiastic material layer, the viscoeiastic material may comprise up to 100% by weight of tne layer A plasticizer, if present, may comprise up to 30% py weignt cf the total weignt of tne viscoeiastic material layer. Similarly, tne UV lignt aosoroer, if present, comprises about 2.0 - 5.0% py weignt cf tne tota-_ weignt cf tne viscoeiastic material laver The viscoeiastic material layer s typically within tne range cf 20 - 50 urn thick, w th 25 - 40 ^m oemg preferable, and 30 - 35 urn being most preferable

The recording layer m this embodiment cf the invention is applied to the carrier film m the form of an emulsion, preferable a water-based emulsion, and allowed to dry. The structure of tne dried film is that cf adhesive particles distributed throughout an essentially continuous layer of tne water-soluble ink abscroer . The size of the adhesive particles is typically m the range of 0.08 - 3.0 ^m, with a O . lum particle size being preferred. The adhesive particles have a strand- like conformation.

The ink aosorbmg layer may oe deposited over tne adhesive layer m the form cf an aqueous solution containing the dispersed adhesive and the layer is dried below the minimum film for forming temperature of the adhesive dispersion.

The heat activatable adhesive and ink absorber together constitute 93 - 98% of the total weight cf the image recording layer. Preferable, the heat activated adhesive and ink aosorber comprise from 94 - 98% and most preferapie, from 97 - 98% cf tne total weight of the recording layer. The heat activatable adhesive comprises about 48 - 64 pph of tne total weight of the image recording layer. Preferably, the heat activatable adhesive comprises 50 - 60 ph and most preferably, 57.8 - 59.8 pph cf the total weight cf the image recording layer, while the ink absorber comprises 34 - 50 pph, preferably 39 - 49 pph, or most preferaply, 39.2 - 41.2 ppn cf the total weight cf the image recording layer. The balance of the image recording layer comprises optionally comprises surfactant and/cr a thickener. The image recording layer may be deposited directly on to the layer of viscoeiastic material and subjected tc conditions for promoting drying. However, better results may be obtained by deposition the ink recording material on a release sheet, subjecting the material to conditions for promoting drying the image recording layer. When dry, the image recording layer is placed directly on the layer of viscoeiastic material. The release sheet may be removed either prior tc or subsequent to placing the image recording layer en the layer of viscoeiastic material .

Having generally described the invention, the following examples are included fcr the purposes cf illustration sc that the invention may be more readily understood and is in no way intended tc limit the scope of the invention unless otherwise specifically indicated.

Examples of the Invention

A group of samples of the printable laminate having a carrier film and ink absorbing layer were prepared according to Examples 1-6. Examples 1-4 use ink absorbers cf which at least one in each formula is thermoplastic, whereas Example 5 and 6 use ink aoscrbers which are not notably thermoplastic .

EXAMPLE 1

A piece cf carrier film was prepared fcr coating with an ink absorber layer. The carrier film used was an oriented polypropylene film commercially available under the name ΞTICOURT ETM, from Hoechst Trespaphan, of Swindon, Wiltshire, UK. The carrier film was found to have a thickness cf approximately 57 μm.

is A mixture cf image recording _ayer material was prepared from the following ingredients in the amounts as indicated:

The mixture was applied to the carrier film and dried at approximately 50 "C. A sufficient amount cf the mixture was used so that upon drying the amount cf material comprising the ink absorbing layer is approximately 25 grams per square meter.

A test print was made with the laminate by printing an image on the laminate with a CHROMA 24 ink jet printer, commonly available from Encad Inc., San Diego, CA, USA. Two samples of the printed laminate cf this example were prepared in this manner. A first sample was laminated to a piece cf foam board of 3mm thickness and a second sample was laminated tc a piece of expanded PVC Board cf 3mm thickness using a roller iaminator set tc 100°C at a pressure of 80 psi with a feed rate speed of 2 feet per minute . Subsequent tc laminating, the printable laminate and mounting board were permitted to cool to room temperature. Adhesion of the laminate to the target board of each sample was tested using a sample pull test. In the test, a pulling force was applied to the laminate until separation cf the printable laminate from the mounting ooarα occurreα. If tne laminate carries awav part paper or ne moun: nr coarc quality cf adhesion is considered good. If the printable laminate peels away from the mounting board without carrying away a pcrtion of the surface paper, the adhesion is considered poor. In the case of non paper-coated board, if the laminate separates with difficulty from the board or the carrier delaminates from the image containing layer, the adhesion is considered good. The printable laminate of this Example was found to provide good adhesion to the mounting board.

EXAMPLE 2

Using the same carrier film as in Example 1 a printable laminate was prepared by applying a coating cf an ink absorber layer 25g dry weight! per square meter of the laminate. The ink absorber layer was prepared from:

The image recording layer was dried and printed with an image as in Example 1 above. A first sample of the printable laminate cf Example 2 was laminated to a foam board of 3mm thickness and a second sample was laminated to an expanded PVC board cf 3mm thickness using a roller laminator set to 100 C and a pressure of 80 psi, and a feed rate cf 2 feet per minute. Adhesion tc both the expanded PVC board and foam board was found to be very good.

EXAMPLE 3A

A printable laminate film was prepared using a ccrona discharge treated polyester fiim by depositing the image recording layer material in an amount cf 35g per square meter (dry weight) on the carrier film. The ink absorbing layer was dried at a temperature below 58 "C . The formula of the ink absorbing layer is as fellows :

After the ink absorbing layer had dried it was printed as an Example 1 with GS Ink Set of a CHROMA 24 Ink Jet Printer. The printed image was allowed to dry and a first sample of the printed image was laminated to a 3mm foam board and a second sample of the printed image laminated to a 3mm expanded PVC board using a roller laminator set at 100°C, a pressure of 80" psi, and a feed rate of 2 feet per minute. On peel testing adhesion of the laminate tc both the foam board and the expanded PVC board was found to be very high.

zz EXAMPLE 3B

Example 3Ξ is quite similar to Example 3A except that the ink absorber cf Example 3A (a blend of cationic polymers) is further blended with a relatively small amount of cellulose ether. The preferred dry weight coat of the image layer according to Example 3B is between 28 and 30 grams per square meter, preferably on the DEEP CRYSTAL or CRYSTAL MATT carrier film previously described. This gives luster and matt products respectively. A simple gloss effect can be obtained by coating polyester film of 50 microns tnickness. In this embodiment, the dry weight percent cf the polyurethane can be in the range of 40 50^: range of tne cationic polymer blend can be 45 - 50%; and the range of the cellulose ether can be about 3 - 10%. The effective dry weight range can be between about 25 - 35 , preferably 28 - 30, grams per square meter. EXAMPLE 4

A corona discharge treated polyester film was used as the carrier fiim to which was applied a mixture cf the ink absorbing layer material in an amount cf Ξ5g per square meter αry weignt The formula cf the image recording layer material as follows :

The ink absorbing layer material was applied to the film and dried at temperature below 58°C. The printable laminate was then printed and laminated tc a 3mm foam board and 3mm expanded PVC board as described in the previous examples. Peel testing showed that adhesion to both the foam board and the expanded PVC board was very high.

Examples 1 - 4 support a preference that at least one of the absorber materials have thermoplastic adhesive properties (e.g., the vinyl pyrrolidone - vinyl ester copolymers LUVISKOL VA64, PVP/VA S-630 and Coilacoi VL; Klucel Ξ; and poiyoxazoiine . EXAMPLE 5

As in the examples above a printable laminate was prepared by forming an image recording layer on a corona discharge treated polyester fiim. The image recording layer had a dry weight of 35g per square meter and was dried at a temperature below 58^CC. The formula of the image recording layer material is as follows :

As in the previous examples the printable laminate was printed with an image, allowed to dry, and a sample laminated to a 3mm foam board and a second sample laminated to a 3mm expanded PVC board. On peel testing, adhesion to both the foam board and the expanded PVC board was found to be very high.

EXAMPLE 6

A mixture of ingredients for forming an ink absorbing layer was deposited en to a corona discharge treated polyester fiim. The dry weight cf the ink absorbing layer was about 35g per square meter. After application of the material, the ink absorbing layer was dried at a temperature below about 58 °C. The formula of the ink absorbing mixture was prepared from the following components :

As in previous examples the printable laminate was printed with an ink jet printer. A first sample of the laminate was affixed to the 3mm foam board and a second sample affixed to a 3mm expanded PVC board. Peel testing revealed that adhesion to both the foam board and the expanded PVC board was very high.

Additional samples cf a printable laminate having a layer cf a viscoeiastic material according to the present invention were prepared according tc Examples 7, 8 and 9. EXAMPLE 7

The printable laminate comprising a carrier fiim, a layer of a viscoeiastic polymer and an image recording layer was prepared as follows : A polyester film having a thickness of 23 um was coated with a acrylic copolymer tc form the layer of viscoeiastic material . The acrylic polymer used is commercially available under the designation 180-1846_. from National Starch and Chemical Limited, United Kingdom. The viscoeiastic material was applied in an amount equivalent to 30g per square meter, dry weight .

The image recording _^aver was :ormeα rrom composition as fellows:

Ingredients Description weight Amt. Dry Weight Amt. KLUCEL E (modified cellulose) 7.6 wt . % 38.9 wt . %

WBV 110 (vinyl resin) 22.8 wt. % 57.1 wt . % deiomzed water (diluent) 68.1 wt . %

LUMITEN AFK (surfactant) C .7 wt . % 2.1 wt .

PLURONIC PE6100 (surfactant) 0.4 wt . % 1.9 wt . Ammonia ΞG=0.88 (neutraliser) 0.4 wt . %

The image recording layer was first deposited directly on a release liner, such as POLY-SLIK 110-80, available from Rexam Release, Apeldoorn, Holland, at a dry coat weight cf 24 - 28 grams per square meter. The ink recording layer was then laminated to the extensible polymeric layer and the release liner removed. Thereafter, the ink recording layer was printed with an image of a GS Ink Set by a Chroma 24 ink jet printer. The image was permitted to dry and then the printable laminate was attached to a foam board target substrate using a roller laminator set at 100°C, a pressure of 80 PSI, and a feed rate of 2 feet per minute. It was found that an acceptable level cf adhesion was obtained between the surface cf the ink recording layer and the foam board.

EXAMPLE 8

In this example a 50 um thick polyester fiim was coated with a dispersion cf a polyurethane (WITCOBOND 233-22) as the extensible polymer in an amount equivalent tc 20g per square meter of fiim, dry weight.

The image recording layer was prepared according to the formula as follows:

Inσredients Description Weiσht Amt. Dry Weiσht Amt.

LUVISKOL K90 (vinyl pyrrolidone; 15.0 v: . % 97.4 wt. % deionized water (diluent) 84.2 wt. %

LUMITEN IRA (surfactant) 0.8 wt . % .6 wt . %

The image recording layer was formed on the release liner at a dry coat weight in the range cf 14 - 18 grams per square meter, then transferred to the viscoeiastic material layer which was previously formed en the carrier film. An image was printed on the outer surface of the recording layer as described in Example ~ above, and a sample laminated tc foam board as previously described.

On peel testing it was found that an acceptable level of adhesion was obtained between the image surface and the board. When the same composition cf ink recording was coated on to a polyester film with a less viscoeiastic primer, it was noted that a negligible level of adhesion was obtained between the film and the image coating. This indicates that the structure and materials of the present invention have greater resistance to delamination than other materials which are known m the art. EXAMPLE 9

In this example, the carrier fiim was coated with viscoeiastic polymer (National 180 - 1846 as in Example 7) at a ccat weight in the range cf 28 - 32 grams per square meter, which was allowed to dry.

The image recording layer was prepared using a phenoxy resin m the formula as follows:

Inσredient Description Weiσht Amt. Dry Weiσht Amt . PKHW-35 phenoxy resin 69.6 wt. % 77.0 wt. % ammonia alkali and 0.8 wt. % neutranzer

CRODATERIC ampnoteric wt .5 wt . CYNA surfactant

NATIONAL PVA , aqueous 1 .9 wt . 9.7 w . 072-0202 solution;

GLASCOL cationic 11.6 wt . 10.8 wt . DP6-7132 Dolvmer deionized water (diluent; 2.4 w .

The image recording layer was deposited on a release liner and allowed to dry. The image recording layer was then transferred tc the viscoeiastic material layer previously formed or. the carrier film. An image was printed en the recordinα layer and then laminated to

acceptable level cf adhesion was obtained between the imaged layer and the foamboard.

As will be apparent to persons skilled in the art, various modifications and adaptations cf the structure and materials described above will become readily apparent without departure from the spirit and scope of the invention.

Claims

C L A I M S :

1. A printable laminate comprising : a substantially transparent film carrier naving opposite first and second sides; a tnermoplastic image recording layer naving an inner surface directly supported by one of said sides of the carrier and an exposed outer surface for receiving

wherein said image recording layer comprises a heat activated adhesive and an nk aosorber which together constitute at least 90% cf the total weight of tne recording layer; wnerem said heat activated adnesive s one or more adnesives selected from the group consisting of polyuretnanes, vinyl ester copolymers, acrylic copolymers and ionomeric copolymers,- and said ιnκ absorber is one or more ink aosoroer materials selected from tne group consisting of blends of cationic polymers, blends of cationic polymers and cellulose ether, and polyvinyi alcohol.

2. The printable laminate of claim 1, wherein the neat activateα adnesive comprises in tne range cf 33 - ^""^{^} ppn parts per nundred weight of tne total weignt cf tne recording layer.

3. The printable laminate of claim 2, wherein the neat activated adhesive comprises at least 48.3 pph of tne total weight of the recording layer.

4. The printable laminate of claim 1, wnerem tne ink aosoroer material comprises at least 20 pph of the total weignt of the recording layer.

5. The printable laminate of claim 4 , wnerem tne ιnκ apsoroer comprises at least aoout 22 ppn cf tne total weignt of the recording layer.

6. The printable laminate cf claim 1, wherein tne recording layer is substantially ciear or becomes clear on the application of heat and pressure during sealing.

7. The printable laminate of claim 1, wherein the carrier is selected from the group consisting of polyester, polypropylene, polyvinyi, chloride, and polyvinyi fluoride film.

8. The printable laminate of claim 1, wherein tne recording layer is a dry film naving a structure n the form of particles of heat activated adhesive the range of 0.08 - 3.0 um distributed througnout a supstantially continuous layer of ink absorber.

9. The printable laminate of claim 8, wnerem the heat activated adhesive has a strand- like conformation.

10. The printable laminate of claim 1, wherein the adhesive is an acrylic ester copolymer.

11. The printable laminate cf claim 1, wnerem tne adhesive is an lonomer formed from the salts of olefins and unsaturated acid copolymers .

12. The printable laminate of claim 1, wnerem tne heat activated adnesive is polyuretnane and the ιnκ absorber is a blend cf cationic polymers and cellulose ether.

13. The printable laminate of claim 1, wnerem the neat activated adnesive is vinyl ester copolymer and tne ink apsoroer is a blend of cationic polymers .

14. The printable laminate of claim 1, wherein the heat activated adhesive is an ionomeric copolymer and the ink absorber is a blend of cationic polymers.

15. The printable laminate of claim 1, wherein the heat activated adhesive is an acrylic ester copolymer and the ink absorber is a blend of cationic polymers .

16. The printable laminate of claim 1, wherein the heat activated adhesive is polyurethane and the ink absorber is a blend cf cationic polymers.

17. The printable laminate of claim 1, wherein the heat activated adhesive is a polyurethane and the ink absorber is a polyvinyi alcohol.

18. The printable laminate of claim 12, wherein the adhesive constitutes in the range of about 40 - 50 pph of the total weight of the image layer.

19. The printed laminate of claim 18, wherein the cationic polymer constitutes in the range of 40 - 50 pph and the cellulose ether constitutes in the range of about 3 - 10 pph cf the total weight cf the image layer.

20. The printable laminate of claim 19, wherein the image recording layer has a dry coat weight in the range of 25 - 35 gram per square meter.

21. The printable laminate of claim 19, wherein the thickness of the image layer is about 26 micron.

22. A printable laminate comprising : a substantially transparent carrier fiim having opposite first and second sides; a substantially uniform thermoplastic image recording layer having an inner surface directly supported by one side of the carrier film and an exposed outer surface for receiving printing ink; the recording layer comprising:

(i) 40 - 65 weight per cent of a first, material which is a thermoplastic, heat activated adhesive; and

(ii) at least 75 per cent of the balance being a second material which is an ink absorbing, thermoplastic, cationic polymer material.

23. The printable laminate of claim 22, wherein the first material is a polyacryiate resin and the second material is a vinyl pyrroiidone-vinyi ester copoiymer.

24. The printable laminate of claim 22, wherein the first material is an ionomeric copoiymer and the second material is a vinyl pyrroiidone-vinyl ester copoiymer.

25. The printable laminate of claim 22, wherein the first material is polyurethane, the second material is a vinyl pyrrolidone-vinyl ester copolymer, and at least 5 per cent of said remaining weight is a vinyl pyrrolidone homopolymer.

26. The printable laminate of claim 22, wherein the first material is polyurethane, the other material is a vinyl pyrroiidone-vinyi ester copoiymer, and at least 5 per cent of said remaining weight is a modified cellulose .

27. The printable laminate of claim 22, wherein the cationic polymer contains trivalent nitrogen or quaternary nitrogen.

28. A printable laminate comprising: a substantially transparent film carrier having opposite first and second sides; a viscoeiastic layer naving an inner surface and an outer surface, said inner surface directly supported by one of said sides of tne carrier; and a thermoplastic recording layer having an inner surface directly supported on tne outer surface of said viscoeiastic layer and en exposed surface fcr receiving printing ink; wnerem said viscoeiastic layer comprises one or more extensible, viscoeiastic polymers selected from the group consisting of polyuretnanes, acrylics, vmyis, outadiene-styrene copolymers; and said recording layer comprises an ιnκ aosoroer selected from the group consisting of blends of cationic polymers, blends of cationic polymers and cellulose ether, and polyvinyi alcohol; and a neat activatable adnesive selected from among the group consisting of polyuretnanes, acrylics, v yis, vinyl ester copolymers, acrylic ester copolymers, ionomeric copolymers, butadiene-styrene copolymers, lsoprene-styrene copolymers, polychloroprenes, olefinic polymers, and phenoxy resins.

29. The printable laminate as claimed claim 28, wherein : said image recorα g layer tne combmeα weignt of the ιr. aosoroer and heat activatable adhesive comprise at least 93% by weignt of the recording layer, and in the viscoeiastic polymer comprises at least 60% by weight of the viscoeiastic layer.

30. The printable laminate as claimed in claim 29, wherein said a plasticizer comprises up to 30% Py weight of the viscoeiastic layer.

31. The printable laminate as claimed claim 28, wherein tne recording layer is a dry film naving a structure tne form of particles cf neat activatao e adhesive cf approximately of from 0.08 to 3 u in diameter, distributed within a substantially continuous layer of ink absorber.

32. The printable laminate as claimed in claim 28, wherein the recording layer is substantially ciear of becomes ciear on application cf heat and pressure during sealing .

33. The printable laminate as claimed in claim 32, wherein the carrier is selected from the group consisting of ciear polyester, .polypropylene, polyvinyi chloride, and polyvinyi fluoride film.

34. A printable laminate comprising: a carrier film; a viscoeiastic layer; and an image recording layer; wherein said viscoeiastic layer comprises one or more extensible viscoeiastic polymers.

AMENDED CLAIMS

[received by the International Bureau on 15 May 2000 (15.05.00) original claim 28 amended; remaining claims unchanged (2 pages)] a viscoeiastic layer having an inner surface and an outer surface, said inner surface directly supported by one of said sides of the carrier and a thermoplastic recording layer having an inner surface directly supported on the outer surface cf said viscoeiastic layer and en exposed surface for receiving printing ink; wherein said viscoeiastic layer comprises one or more extensible, viscoeiastic polymers selected from the group consisting cf polyurethanes, acrylics, vinyls, butadiene-styrene copolymers, isoprene- styrene copolymers, polychloroprenes and olefinic polymers; and said recording layer comprises an ink absorber selected from the group consisting of blends of cationic polymers, blends of cationic polymers and cellulose ether, and polyvinyi alcohol; and a heat activatable adhesive selected from among the group consisting of polyurethanes, acrylics, vinyls, vinyl ester copolymers, acrylic ester copolymers, ionomeric copolymers, butadiene-styrene copolymers, isoprene-styrene copolymers, polychloroprenes, olefinic polymers, and phenoxy resins .

29. The printable laminate as claimed in claim 28, wherein: in said image recording layer the combined weight of the ink absorber and heat activatable adhesive comprise at least 93% by weight of the recording layer; and in the viscoeiastic polymer comprises at least 60% by weight of the viscoeiastic layer.

30. The printable laminate as claimed in claim 29, wherein said a plasticizer comprises up to 30% by weight of the viscoeiastic layer.

31. The printable laminate as claimed in claim 28, wherein the recording layer is a dry film having a structure in the form cf particles of heat activatable adhesive cf approximately of from 0.08 to 3 μm in diameter, distributed within a substantially continuous layer of ink absorber.

32. ^' The printable laminate as claimed in claim 28, wherein the recording layer is substantially clear of becomes clear on application of heat and pressure during sealing.

33. The printable laminate as claimed in claim 32, wherein the carrier is selected from the group consisting of clear polyester, .polypropylene, polyvinyi chloride, and polyvinyi fluoride film.

STATEMENT UNDER ARTICLE 19(1)

Claim 28 has been replaced by an amended claim bearing the same number. The amended list of viscoeiastic polymers now includes isoprene-styrene copolymers, polychloroprenes and olefinic polymers. Support for the amendment is found on page 5 lines 9 and 10 of the specification.