EP0921441A1 - A transfer foil for use in electrostatographic printing - Google Patents
A transfer foil for use in electrostatographic printing Download PDFInfo
- Publication number
- EP0921441A1 EP0921441A1 EP97203814A EP97203814A EP0921441A1 EP 0921441 A1 EP0921441 A1 EP 0921441A1 EP 97203814 A EP97203814 A EP 97203814A EP 97203814 A EP97203814 A EP 97203814A EP 0921441 A1 EP0921441 A1 EP 0921441A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- image
- layer
- transfer foil
- support
- toner
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
- G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
- G03G7/002—Organic components thereof
- G03G7/0026—Organic components thereof being macromolecular
- G03G7/004—Organic components thereof being macromolecular obtained by reactions only involving carbon-to-carbon unsaturated bonds
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
- G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
- G03G7/002—Organic components thereof
- G03G7/0026—Organic components thereof being macromolecular
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
- G03G7/0006—Cover layers for image-receiving members; Strippable coversheets
- G03G7/002—Organic components thereof
- G03G7/0026—Organic components thereof being macromolecular
- G03G7/0033—Natural products or derivatives thereof, e.g. cellulose, proteins
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G7/00—Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
- G03G7/0053—Intermediate layers for image-receiving members
Definitions
- This invention relates to a transfer foil used for the production of images that can be transferred to other substrates. It relates especially to a transfer foil useful in electro(stato)graphic printing methods for the production of images that can be transferred.
- Decoration of objects by hot-stamping or in mould decoration proceeds by applying, under pressure and/or heat, a foil carrying a coloured layer that is transferable by heat and pressure.
- the foil carries a uniform coloured layer.
- the object is decorated by pressing the foil against the object with an image bearing stamper. This latter kind of process creates a lot of wasted colour since only a small part of the coloured layer is transferred.
- electro(stato)graphic means Printing colour images on transfer foils by electro(stato)graphic means is well known in the art.
- the advantage of electro(stato)graphic methods, for making such images, over traditional printing techniques (offset, screen-printing, etc.) is the simplicity of the electro(stato)graphic system, the price and, when using dry electrostatic printing, the fact that the preparation of such transfer foils can be used with very little impact on the environment.
- the electro(stato)graphic methods make it possible to make transfer images in small edition and even to personalise the images.
- electro(stato)graphic imaging methods are often digital printing methods present an advantage over the printing methods that are traditionally used for making images transferable by hot stamping or in-mould decoration.
- DE-A-27 27 223 a method for transferring images onto cotton T-shirts by first producing an electrostatic latent image in a known manner on an intermediate substrate, coating the latent image with thermoplastic toner, reversing the polarity of charge to transfer the toner image to a second intermediate substrate coated on both sides with a layer (preferably of polyethylene) and a thermoplastic clear lacquer layer adjacent the toner image.
- the toner image fixed on the substrate is transferred to the T-shirt by application of heat and pressure.
- US-A-4 064 285 a printing process in which an image is formed in toner powder by a xerographic method and transferred to a subbing layer on a release material carried by a substrate in sheet form. The image is then heated in contact with a fabric, wood or polymeric material and the substrate coated with release material is removed.
- the subbing layer is a low-melting polymer selected from vinyl or vinylidene chloride, vinyl acetate, methyl-, ethyl- or butylmethacrylate or their mixtures or copolymers.
- the release material is a silicon or fluorinated polymer and the substrate is preferably paper.
- the process of this disclosure is used to print individual pictures, letters, words, etc. on fabrics, garments, household articles, furniture etc. Materials can be decorated with personalised images in full colour at low cost by a simple process using known xerographic methods and equipment. The images of this disclosure are said to be permanent, adhere well and flexible.
- JP-A-63 296982 an electro(stato)graphic method for producing coloured transfer images for transfer onto any material, e.g., thick paper, ultra thin paper, film, acrylic plate, metal plate, etc.
- the system is said to be less costly than conventional transfer lettering.
- the method uses two foils, a first one whereon an electro(stato)graphic transfer image is printed, the transfer image is then transferred to a second (thin) foil and this foil is used to decorate the object.
- a xerographic process comprises first depositing an electrostatic image, xerographically, onto a master dry transfer carrier sheet which is adhesive with respect to the developed image.
- the electrostatic image is developed with a dry toner composition containing a thermoplastic agent, to give an image which is pressure-transferable to a receptor surface.
- the top surface of the developed image is then contacted with the receptor surface and pressure is applied to the non-image-bearing side of the carrier sheet to transfer the image to the receptor surface.
- Transfer sheets bearing the required symbols can be made as and when required, and transferred to a wide variety of substrates in the usual way by pressure on the back of the transfer sheet.
- an image carrier sheet for use in image transfer processes has a flexible web base carrying in order (1) a surface layer of polymeric material, and (2) a thermoplastic coating which is receptive to toner.
- a toner image is formed xerographically on the thermoplastic coating.
- the sheet carrying the image is then assembled with a receiving substrate of textile material and subjected to heat and pressure.
- the thermoplastic coating separates from the polymeric surface layer so that the toner image transfers to the textile substrate, wetting the substrate and flowing into intimate contact with the fibres.
- the disclosure is interested especially in a transfer method for printing T-shirts.
- the image on the transfer sheet may be semi-permanent enabling the sheet to be handled without damaging the image.
- a method of pattern transfer has the pattern reproduced from an original by an electrostatic or preferably a digital laser photocopier onto a transfer sheet is then juxtaposed to an adhesive, moulding or lacquer layer covering the foil.
- the transfer sheet is peeled off and the dry toner particles are pressed onto the outside or inside of a display window or similar image carrier, which is not necessarily plane.
- the method is said to be useful for the production of simple textiles, plastics, and ceramics similar artefacts, producing fast and sharp decoration on highly curved surfaces without recourse to harmful solvents.
- a method of pattern transfer having the pattern reproduced from an original by an electrostatic or preferably a digital laser photocopier onto a transfer sheet.
- the pattern is then juxtaposed to an adhesive, moulding or lacquer layer covering the foil.
- the transfer sheet is peeled off and the dry toner particles are pressed onto the outside or inside of a display window or similar image carrier, which is not necessarily plane.
- the method is said to be very suitable for decoration of simple textiles, plastics, and ceramics similar artefacts.
- the method is said to produce fast and sharp decoration on highly curved surfaces without recourse to harmful solvents.
- a transfer foil to be imaged by an electro(stato)graphic process comprises a support, a release layer, and a transferable adhesive layer secured on the release layer.
- the toner particles adhere on the adhesive layer and during transfer, the image is adhered to the object to be decorated by the adhesive layer which together with the image and the release layer is transferred as a whole to the image.
- the release layer and the adhesive layer form a kind of protective layer over the image, but this can have a detrimental effect since on the areas of the substrate to be decorated where no image is expected toner receiving layer is deposited that can impair the hue, the surface relief, etc. of the substrate that can be decorated.
- the objects of the invention are further realised by providing a transfer foil comprising in consecutive order a support with a thickness equal to or lower than 75 ⁇ m, a release layer, adhering to said support with a force F PET , and an image receiving layer with a polymeric binder and having thickness d, a cohesive force F coh and adhering to said release layer with a force F rela characterised in that F PET > F rela > F coh .
- a transfer foil that can only be used with toner particles that are melting at fairly low temperature has only a restricted usefulness.
- both the toner image and the toner receiving layer, whereon the toner image has been fixed are transferred to the object to be decorated.
- the toner image is strengthened by the toner receiving layer wherein the particles are fixed, but a transfer foil wherein both toner image and toner receiving layer are transferred, has the problem that the receiving layer is also transferred from the areas of the transfer foil, that do not bear a toner image to the substrate to be decorated. This can give a detrimental effect since on the areas of the substrate to be decorated where no image is expected toner receiving layer is deposited that can impair the hue, the surface relief, etc. of the substrate that can be decorated.
- a transfer foil with a toner receiving layer whereon a toner image can be fixed and from which the image can be transferred together with the toner receiving layer but where the toner receiving layer is only transferred with the image and not from the non-imaged parts of the foil, could solve both problems referred to above. It would give a decorated substrate with a toner image that is physically strong and with non impairing of the surface of the substrate in the parts that do not bear an image.
- the cohesive force (F coh ) of the toner receiving layer determines the kind of break in the receiving layer : when this force is rather low, then the layer breaks cohesively, i.e. part of the layer stay on the support and some parts (in the case of the toner receiving layer in an transfer foil of this invention, the parts carrying the toner particles) are transferred to the substrate to be decorated and the layer breaks at the boundary between the toner bearing parts and the non-toner bearing parts.
- the toner receiving layer, in a transfer foil according to this invention, comprise a polymeric binder and the cohesive force of this layer can be adjusted by adding a "promoter for cohesive break" to the layer.
- the "promoter for cohesive break” is preferable selected from the group consisting of spacing particles with an average volume diameter d v50 ⁇ 0.9d, waxes, polymers, different from said polymeric binder and cross-linking agents for said polymeric binder.
- particulate materials useful for adding to the image receiving layer to reduce cohesivity include inorganic particles (e.g. calciumcarbonate, silica, talc, titan dioxide, aluminium oxide) and organic particles, like particles of poly(tetra-fluoroethylene, polymethylsilylsesquioxane (TOSPEARL, trade name, available from Toshiba Silicone) and TEFLON MP (trade name for particles with fluoro-additives available from du Pont).
- the spacing particles for use as promoter for cohesive break are in this invention are preferably polymeric spacing particles having F-atom and/or Si-atoms at the surface and have preferably an average volume diameter (d v50 ) that is at least 90 % of the thickness, d, of the layer.
- spacing particles are used as "promotor for cohesive break", it is preferred to use polymeric particles of poly(methylsilylsesquioxane).
- polymeric particles sold under trade name TOSPEARL, by Toshiba, Japan.
- spacing particles are used as "promotor for cohesive break"
- the spacing particles can be present in an amount between 1 and 50 % by weight (wt/wt) with respect to the total weight of the toner receiving layer, the spacing particles are preferably present in an amount between 5 and 25 % by weight (wt/wt) with respect to the total weight of the toner receiving layer.
- Waxes useful as promoter for cohesive break in a layer of this invention can be natural as well as synthetic waxes.
- Wax is a technological collective word for materials that have "waxy” behaviour. Compounds with "waxy” behaviour can best be described by the physical properties of the compounds. In general the greater number of waxes are characterised by the following criteria : ⁇ they have a melting point of at least 40°C (this distinguishes waxes from oils and fats), a relatively low melt-viscosity and when molten they do not form strings like threads (this distinguishes waxes from resins and plastics). "Waxy” compounds do not show chemical transformation at elevated temperatures (this last property is often cited as borderline between waxes and natural resins).
- Waxes and wax-like materials, useful as cohesive break promoter in an image receiving layer, of this invention can be selected from mineral waxes, natural waxes and synthetic waxes.
- useful mineral waxes include petroleum waxes such as paraffin wax, microcrystalline waxes, ester wax, oxidised wax, montan wax, ozokerite and ceresine.
- useful natural waxes include plant waxes such as carnauba wax and Japan wax, and animal waxes such as bee wax, insect wax, shellac wax, spermaceti wax and whale wax.
- Very useful synthetic waxes are generally a higher aliphatic compounds such as higher aliphatic alcohols with formula CH 3 (CH 2 ) n CH 2 OH, wherein n ranges from 6 to 28 or higher aliphatic acids with formula CH 3 (CH 2 ) n CH 2 COOH, wherein n ranges from 6 to 28.
- unsaturated higher aliphatic alcohols or acids are useful as waxes in this invention.
- esters of the above fatty acids e.g., ethyl stearate, lauryl stearate and ethyl behenate, amides of the above fatty acids : e.g. stearic acid amide.
- dimethylglycolphthalate can be used.
- the above mentioned waxes or wax like materials can be employed in the form of a solution or dispersion (emulsion). Most preferably the wax will be used as a waterborne or solvent based dispersion (emulsion).
- polymeric waxes are very useful as promotor for cohesive break in a toner receiving layer on a foil according to this invention.
- Very useful polymeric waxes for use as "promoter for cohesive" break in this invention are compounds selected from the group consisting of high density polyethylene waxes, polypropylene waxes, polyvinylstearate, polyethylene sebacate, sucrose polyesters, higher aliphatic alcohols with formula CH 3 (CH 2 ) n CH 2 OH, wherein n ranges from 20 to 300 or higher aliphatic acids with formula CH 3 (CH 2 ) n CH 2 COOH, wherein n ranges from 20 to 300 and polyalkylene oxides.
- a very useful wax can be chosen from the polypropylene waxes, sold under trade name CERIDUST by Hoechst, Germany.
- Other waxes very useful as wax in a toner receiving layer in a transfer foil of this invention are sold under trade name UNILIN 450, UNILIN 700,( trade names of PETROLITE, 6910 East 14th street, TULSA, Oklahoma 74112, USA for polyolefinic alcohols with average molecular weight of 425, 700), UNITHOX 720, a trade name for a hydroxyterminated, polyolefinic polyoxyethylenic macromolecule, with average molecular weight of 875 of the same PETROLITE company. and a monofunctional carboxyl terminated polyolefine as UNICID 700, a trade name of PETROLITE for a polyolefinic monocarboxylic acid with average molecular weight of 700.
- Polymeric compounds useful as promoters for cohesive break can be hydrophilic colloid materials, such as polyvinylalcohol, gelatine, hydroxyalkylcellulose, polyvinylpyrrolidon, carboxymethylcellulose, methylcellulose, polyethylene oxide and gum Arabic.
- suitable polymers as promotor for cohesive break comprise polydimethyl siloxane, methylphenylsilicone resin, tetrafluoroethylene telomer (e.g. VYDAX -trade name of du Pont, Wilmington, USA), organosilicon copolymer (e.g.
- polystyrene and vinyl chloride copolymers polyvinylidene chloride and vinylidene chloride copolymers, polyethylene and polypropylene, ethylene copolymers, polystyrene, styrene copolymers.
- poly(meth)acrylates and (meth)acrylate copolymers polyamide resins such as alcohol-soluble POLYAMIDE CM-8000 (trade name of Toray Co.,Ltd.), synthetic rubber, chlorinated rubber, vinylacetate copolymers, polyvinyl acetal resins, polyhydroxystyreen (e.g. RESIN M ; trade name of Maruzen Co.,Ltd. Japan), can be used as promoter for cohesive break.
- the image receiving layer in a transfer sheet according to this invention comprises preferably a polymer that has good film-forming properties and that is transparent.
- a binder for the image receiving layer is further chosen on the basis of the adherence of toner particles to it, the ease with which such a layer is separated from the support and/or from an intermediate release layer on said support. In that case it is preferred that said release layer stays, after transfer on the support and is in its totality peeled away together with said support.
- a binder for the image receiving layer of a transfer sheet of this invention that so that the cohesive properties of the that that layer can easily be tuned so that after image-wise transfer of the image, the receiving layer is image-wise transferred together with the toner image and thus giving good physical properties (scratch resistance, optical clarity, solvent-resistant, gloss,...) to the transferred image.
- image receiving polymers chosen with regard to the demands outlined above, include nitro-cellulose, polyvinylidene chloride and vinylidene chloride copolymers, poly(meth)acrylates and (meth)acrylate copolymers, (e.g.
- UCAR VAGD trade names of Union Carbide
- polyvinyl acetate e.g. SCRIPTSET 540 trade name of Monsanto, USA
- polyvinylacrylates e.g., polyvinyl chloride and vinyl chloride copolymers
- polyvinyl acetate/polyvinyl chloride copolymers such as HOSTAFLEX CM131 trade name of Hoechst Celanese Corp, USA.
- the binder resin of a toner receiving layer in a transfer foil of this invention comprises a polymer selected from the group of homo-polymers of methylmethacrylate, copolymers including methylacrylate moieties, co-polymers including methylmethacrylate moieties, nitrocellulose being nitrated for at most 12.5 mol %, polyvinylacetate and polyvinylbutyral.
- Nitrocellulose being nitrated for at most 12.5 mol % is available from Wolff Walsrode AG, Walsrode, Germany under trade names Nitrocellulose TYPE A, 10.9 to 11.3 % nitration, TYPE AM, 11.4 to 11.7 % nitration and TYPE E, 11.8 to 12.2 % nitration.
- the image receiving layer in a transfer sheet according to this invention may have a thickness of about 0,5 ⁇ m to about 10 ⁇ m. More preferable the thickness is situated between 1 and 5 ⁇ m.
- the toner receiving layer in a transfer foil according to this invention can be a single layer, with a thickness as given above, or a double or multiple layer if so desired, e.g., for enhancing the coating quality (smoothness, avoiding of pin-holes, etc.). When double or multiple layers are coated, the composition of the respective layers can be equal or different.
- the layer or layers of the transfer foil whereon the toner particles are deposited and fixed and that are transferred together with the toner image when using the imaged transfer foil for decoration of objects is the toner receiving layer.
- the image receiving layer in a transfer sheet of this invention can, for enhancing the cohesive break, be partially or wholly cross-linked.
- This cross-linking can be obtained by chemical curing or by radiation curing.
- Polymers containing a chemical reactive group such as a free hydroxyl group like vinyl acetal resins (e.g., polyvinyl butyral or polyvinyl formal), present a point of chemical reactivity through which the resins may be made insoluble. Any chemical reagent or resinous material which reacts with secondary alcohols will react with this kind of polymers to inhibit solubility and to promote hardness.
- Possible cross-linking agents are e.g. phenolics, epoxides, dialdehydes, di-or-poly-isocyanates and melamines. Coating properties vary greatly with the type and amount of cross-linking agent used.
- Polymers like modified hydroxy (meth)acrylates e.g.
- JAGOTEX F 253, F 218 and F219 trade names of Ernst Jäger GMBH, Germany
- nitro-cellulose also result in good cross-linking properties when hardened with aliphatic di-or-poly-isocyanates.
- the curing process can be enhanced by the presence of a catalyst.
- a variety of catalysts can be employed to accelerate the speed of the reaction. Possible catalysts are e.g. stannous octoate, zirconium octoate, bismuthstearate and lead stearate.
- UV-curable compositions containing (meth)acrylic monomers or oligomers are also effective to improve the cohesive break of the image receiving layer.
- UV-curable coating can broadly classified into two categories: free radical polymerised and cationic polymerised. The interest in cationically cured compositions has grown the last years. Polymers formed by free radical polymerisation are generally based upon acrylic or methacrylic monomers or oligomers, which are converted to high molecular weight polymers with varying degrees of cross-link density upon exposure to ultraviolet radiation.
- cross-linking when cross-linking is used as means for controlling the cohesive break of the imaging layer, it is preferred to use chemical cross-linking.
- the transfer foil comprises a plastic (synthetic polymer) support, e.g. polyester (polyethyleneterephthalate, polyethylenenaphthalate, etc.), syndiotactic polystyrene, polypropylene, etc.
- a plastic support it is preferred to use a thermoset polymeric foil, since during the fusing of the toner image to the transfer foil, a quite high temperature can be reached. This high temperature entails the risk of wrinkling or wrapping up of the foil when the foil is not thermoset.
- a transfer foil comprising a thermoset support has also the advantage that it does not undergo large dimensional changes during the fusing step.
- the support in a transfer foil according to this invention is preferably less than 75 ⁇ m thick, more preferably the thickness is equal to or lower than 50 ⁇ m.
- the use of a thin support is preferred because with a thin support the transfer foil can, after being imaged, be used for decorating objects that are not flat, because a thin support follows quite easily the contours of the object to be decorated. Further, since the support of the transfer foil is stripped away and has either to be recuperated or discarded, the less material that is present, the better.
- the imaging layer in a transfer sheet according to this invention can be applied to directly to a support and the releasability of said image receiving layer is secured by the fact that the surface of the support, whereon the image receiving layer is applied, is inherently releasable.
- a transfer foil according to this invention comprises in the order given a support with a thickness equal to or lower than 75 ⁇ m, a release layer, adhering to said support with a force F PET' and an image receiving layer with a polymeric binder and having thickness d, a cohesive force F coh and adhering to said release layer with a force F rela characterised in that F PET > F rela > F coh .
- force (F rela ) was in turn lower than the force with which the toner particles adhered, after fixing, to the toner receiving layer (F ton ).
- the release layer may comprise hydrophilic colloid materials, such as polyvinyl alcohol, gelatine, hydroxyalkyl cellulose, polyvinylpyrrolidon, carboxymethylcellulose, methylcellulose, polyethylene oxide, gum Arabic.
- hydrophilic colloid materials such as polyvinyl alcohol, gelatine, hydroxyalkyl cellulose, polyvinylpyrrolidon, carboxymethylcellulose, methylcellulose, polyethylene oxide, gum Arabic.
- Other suitable release layers comprise polydimethyl siloxane, methylphenylsilicone resin, tetrafluoroethylene telomer (e.g. VYDAX trade name of du Pont), organosilicon copolymer (e.g.
- the release layer may have a thickness of about 0,01 ⁇ m to about 10 ⁇ m.
- the release layer comprises a binder selected from the group consisting of polyvinylpyrrolidon, polyvinylalcohol, co-poly(vinylacetate-crotonic acid),polyvinyl chloride, organo-silicon release polymers, waxes or wax-like materials and polymethylmethacrylate.
- an apparatus for producing a master image according to this invention, several means for image-wise or non-image-wise applying of toner particles can be present and said means for depositing toner particles can be direct electrostatic printing means, wherein charged toner particles are attracted to the substrate by an electrical field and the toner flow modulated by a printhead structure comprising printing apertures and control electrodes.
- Said means for depositing toner particles can also be toner depositing means wherein first a latent image is formed.
- said means for depositing toner particles comprise :
- Said latent image may be a magnetic latent image that is developed by magnetic toner particles (in magnetography) or, preferably, an electrostatic latent image .
- an electrostatic latent image is preferably an electrophotographic latent image and the means for producing a latent image are in this invention preferably light emitting means, e.g., light emitting diodes or lasers and said latent image bearing member comprises preferably a photoconductor.
- An apparatus for forming a master images on a transfer foil can be any apparatus for electrostatographic, magnetographic imaging, whatever the toner depositing means, both appartus adapted for monochromatic printing and apparatus adapted for full-colour printing.
- typical examples of very useful apparatus are a commercial CHROMAPRESS (a trade name of Agfa-Gevaert NV, Mortsel, Belgium), used in simplex mode and wherein five toner depositing station are present on one side of the image receiving member (i.e. in this invention the temporary support whereon the master image is formed), or an AGFA XC305 colour copier.
- An apparatus for producing a toner image on a transfer foil according to the present invention can comprise any fusing means known in the art.
- the fusing means can combine heat and pressure, radiant heat e.g. hot air, or infra-red radiation, etc.
- heated pressure rollers can be used and silicone oil is used to impart release properties to the rollers.
- transfer sheets a clear polyethyleneterephthalate support was used. The thickness was between either 12 or 23 ⁇ m.
- this support was used as such without any treatment and the image receiving layer was coated directly on that support.
- the support was provided with a subbing layer as known from the art of photography and a release layer was applied to the support prior to applying the image receiving layer.
- the transfer sheets of all examples were single sided imaged in a CHROMAPRESS (trade name) of Agfa Gevaert NV, Mortsel Belgium, on the side carrying the image receiving layer.
- the developer used was the commercially available developer containing magnetic carrier particles coated with a silicone resin and toner particles comprising a polyester as toner resin and a cyan pigment.
- ABS acrylonitrile-butadiene-styrene polymer
- the four properties were evaluated on a scale from 0 to 4, wherein 0 is very good, 1 is good, 2 is acceptable, 3 is barely acceptable, and 4 is unacceptable.
- Example 1 was repeated, except for the fact that the support was 12 ⁇ m thick.
- PLEXIGUM M345 trade name of Röhm & Haas Germany
- the transfer sheet was imaged and the image transferred as described above .
- a solution of 15 % polyvinylpyrrolidone in ethanol as solvent was coated on a polyethyleneterephthalate support of 12 ⁇ m thick with a subbing layer so has to form a release layer of 1 ⁇ m thick.
- a solution of 15 % polyvinylpyrrolidone in ethanol as solvent was coated on a polyethyleneterephthalate support of 12 ⁇ m thick with a subbing layer so has to form a release layer of 1 ⁇ m thick.
- a solution of 15% polyvinylpyrrolidone and 3 % of amorphous silica particles with particle size d v50 4 ⁇ m in ethanol as solvent was coated on a polyethyleneterephthalate support of 23 ⁇ m thick with a subbing layer so has to form a release layer of 1 ⁇ m thick.
- Example # Thickness support in ⁇ m Relaese layer Image receiving layer E1 23 NO 0 0 1 1-2 E2 12 NO 0 0 3 1-2 E3 12 NO / 2-3 4 4 E4 23 NO 0 0 3 1-2 E5 23 NO / 3 2 1 1-2 E6 23 NO / 0 0 0 1-2 E7 12 YES / 0 0 0 1-2 E8 23 YES 0 0 3 0-1 E9 12 YES A/ 0 0 0 0-1 E10 12 YES 0 0 0 0-1 E11 23 YES PVB/ 0 0 0 0-1
Abstract
A transfer foil comprising a support with a thickness equal to
or lower than 75 µm and, directly adjacent to the support, an image
receiving layer with a polymeric binder and having thickness d, a
cohesive force Fcoh and adhering to the support with a force Frel
characterised in that Frel > Fcoh. Preferably between the support
and the image receving layer a release layer is present.
The cohesive force of the image receiving layer is controlled
by adding a "promotor for cohesive break" to the layer. Such a
promotor is selected from the group consisting of spacing particles
with an average volume diameter dv50 ≥ 0.9d, waxes, polymers,
different from the polymeric binder and cross-linking agents for
the polymeric binder.
Description
This invention relates to a transfer foil used for the
production of images that can be transferred to other substrates.
It relates especially to a transfer foil useful in
electro(stato)graphic printing methods for the production of images
that can be transferred.
Decoration of objects by hot-stamping or in mould decoration
proceeds by applying, under pressure and/or heat, a foil carrying a
coloured layer that is transferable by heat and pressure. In many
applications the foil carries a uniform coloured layer. The object
is decorated by pressing the foil against the object with an image
bearing stamper. This latter kind of process creates a lot of
wasted colour since only a small part of the coloured layer is
transferred.
Printing colour images on transfer foils by
electro(stato)graphic means is well known in the art. The
advantage of electro(stato)graphic methods, for making such images,
over traditional printing techniques (offset, screen-printing,
etc.) is the simplicity of the electro(stato)graphic system, the
price and, when using dry electrostatic printing, the fact that the
preparation of such transfer foils can be used with very little
impact on the environment. Moreover the electro(stato)graphic
methods make it possible to make transfer images in small edition
and even to personalise the images. Also the fact that
electro(stato)graphic imaging methods are often digital printing
methods present an advantage over the printing methods that are
traditionally used for making images transferable by hot stamping
or in-mould decoration.
In DE-A-27 27 223 a method for transferring images onto cotton
T-shirts by first producing an electrostatic latent image in a
known manner on an intermediate substrate, coating the latent image
with thermoplastic toner, reversing the polarity of charge to
transfer the toner image to a second intermediate substrate coated
on both sides with a layer (preferably of polyethylene) and a
thermoplastic clear lacquer layer adjacent the toner image. The
toner image fixed on the substrate is transferred to the T-shirt by
application of heat and pressure.
In US-A-4 066 802 xerographic means to produce transfer images,
mainly for transfer on fabrics are disclosed. Although the main
interest of this disclosure is the decoration of fabrics, it is
disclosed that the pictures may be transferred to other substrates
e.g. glass, metal, synthetic and natural materials.
In US-A-4 064 285 a printing process in which an image is
formed in toner powder by a xerographic method and transferred to a
subbing layer on a release material carried by a substrate in sheet
form. The image is then heated in contact with a fabric, wood or
polymeric material and the substrate coated with release material
is removed. The subbing layer is a low-melting polymer selected
from vinyl or vinylidene chloride, vinyl acetate, methyl-, ethyl- or
butylmethacrylate or their mixtures or copolymers. The release
material is a silicon or fluorinated polymer and the substrate is
preferably paper. The process of this disclosure is used to print
individual pictures, letters, words, etc. on fabrics, garments,
household articles, furniture etc. Materials can be decorated with
personalised images in full colour at low cost by a simple process
using known xerographic methods and equipment. The images of this
disclosure are said to be permanent, adhere well and flexible.
In JP-A-63 296982 an electro(stato)graphic method for producing
coloured transfer images for transfer onto any material, e.g.,
thick paper, ultra thin paper, film, acrylic plate, metal plate,
etc. The system is said to be less costly than conventional
transfer lettering. However the method uses two foils, a first one
whereon an electro(stato)graphic transfer image is printed, the
transfer image is then transferred to a second (thin) foil and this
foil is used to decorate the object.
In US-A-4 216 283 a xerographic process comprises first
depositing an electrostatic image, xerographically, onto a master
dry transfer carrier sheet which is adhesive with respect to the
developed image. The electrostatic image is developed with a dry
toner composition containing a thermoplastic agent, to give an
image which is pressure-transferable to a receptor surface. The top
surface of the developed image is then contacted with the receptor
surface and pressure is applied to the non-image-bearing side of
the carrier sheet to transfer the image to the receptor surface.
Transfer sheets bearing the required symbols can be made as and
when required, and transferred to a wide variety of substrates in
the usual way by pressure on the back of the transfer sheet.
In EP-A-466 503, an image carrier sheet for use in image
transfer processes is disclosed. The sheet has a flexible web base
carrying in order (1) a surface layer of polymeric material, and
(2) a thermoplastic coating which is receptive to toner. A toner
image is formed xerographically on the thermoplastic coating. The
sheet carrying the image is then assembled with a receiving
substrate of textile material and subjected to heat and pressure.
The thermoplastic coating separates from the polymeric surface
layer so that the toner image transfers to the textile substrate,
wetting the substrate and flowing into intimate contact with the
fibres. The disclosure is interested especially in a transfer
method for printing T-shirts. The image on the transfer sheet may
be semi-permanent enabling the sheet to be handled without damaging
the image.
In WO-A-90 13063 a method of pattern transfer has the pattern
reproduced from an original by an electrostatic or preferably a
digital laser photocopier onto a transfer sheet is then juxtaposed
to an adhesive, moulding or lacquer layer covering the foil. The
transfer sheet is peeled off and the dry toner particles are
pressed onto the outside or inside of a display window or similar
image carrier, which is not necessarily plane. The method is said
to be useful for the production of simple textiles, plastics, and
ceramics similar artefacts, producing fast and sharp decoration on
highly curved surfaces without recourse to harmful solvents.
In DE-C-39 43 556 a method of pattern transfer is disclosed
having the pattern reproduced from an original by an electrostatic
or preferably a digital laser photocopier onto a transfer sheet.
The pattern is then juxtaposed to an adhesive, moulding or lacquer
layer covering the foil. The transfer sheet is peeled off and the
dry toner particles are pressed onto the outside or inside of a
display window or similar image carrier, which is not necessarily
plane. The method is said to be very suitable for decoration of
simple textiles, plastics, and ceramics similar artefacts. The
method is said to produce fast and sharp decoration on highly
curved surfaces without recourse to harmful solvents.
Using the electro(stato)graphic methods above do give the
possibility to produce personalised printing using hot-stamping
foils, but the toner image that is transferred can be damaged when
the toner particles forming the image did, during the fixing of the
image, not melt into each other so that no continuous film of toner
particles is transferred.
In EP-A-453 256 a transfer foil to be imaged by an
electro(stato)graphic process is disclosed. The transfer foil
comprises a support, a release layer, and a transferable adhesive
layer secured on the release layer. The toner particles adhere on
the adhesive layer and during transfer, the image is adhered to the
object to be decorated by the adhesive layer which together with
the image and the release layer is transferred as a whole to the
image. In this case the release layer and the adhesive layer form
a kind of protective layer over the image, but this can have a
detrimental effect since on the areas of the substrate to be
decorated where no image is expected toner receiving layer is
deposited that can impair the hue, the surface relief, etc. of the
substrate that can be decorated.
Therefore further transfer foils useful in the production of
transfer images by deposition of electrostatic toner particles on
the foil and methods for using the same are still desirable.
It is an object of this invention to provide a transfer foil to
be imaged with electrostatic toner particles, that gives good image
quality and that has an image that, after being transferred, can
better withstand physical strain.
It is an other object of this invention to provide a toner
image on a transfer foil that can be transferred to a substrate to
be decorated and that after transfer gives a physically strong
image.
It is a further object of the invention to provide a toner
image on a transfer foil that can be transferred to a substrate to
be decorated and that, after transfer, produces an image on the
substrate that carries an image-wise applied protective layer.
Further objects and advantages of the invention will become
apparent from the detailed description of the invention
hereinafter.
The objects of this invention are realised by providing a
transfer foil comprising a support with a thickness equal to or
lower than 75 µm and, directly adjacent to said support, an image
receiving layer with a polymeric binder and having thickness d, a
cohesive force Fcoh and adhering to said support with a force Frel
characterised in that Frel > Fcoh.
The objects of the invention are further realised by providing
a transfer foil comprising in consecutive order a support with a
thickness equal to or lower than 75 µm, a release layer, adhering
to said support with a force FPET , and an image receiving layer
with a polymeric binder and having thickness d, a cohesive force
Fcoh and adhering to said release layer with a force Frela
characterised in that FPET > Frela > Fcoh.
When printing a toner image on a transfer foil of the prior art
and transferring it to a substrate to be decorated, two problems
can arise. In a first case only the toner image is transferred and
the toner receiving layer, whereon the toner image has been fixed,
remains on the foil. When in this case, the toner particles
forming the image do, during the fixing of the image, not melt into
each other, the transferred image is not a continuous film of toner
particles, but a only an accumulation of loosely bounded toner
particles, that can easily be damaged. This problem can be avoided
by using the foil with toner particles that are melting at fairly
low temperature and have a high fluidity at the fixing temperature.
However, a transfer foil that can only be used with toner
particles that are melting at fairly low temperature has only a
restricted usefulness. In a second case both the toner image and
the toner receiving layer, whereon the toner image has been fixed,
are transferred to the object to be decorated. In such a
transferred image, the toner image is strengthened by the toner
receiving layer wherein the particles are fixed, but a transfer
foil wherein both toner image and toner receiving layer are
transferred, has the problem that the receiving layer is also
transferred from the areas of the transfer foil, that do not bear a
toner image to the substrate to be decorated. This can give a
detrimental effect since on the areas of the substrate to be
decorated where no image is expected toner receiving layer is
deposited that can impair the hue, the surface relief, etc. of the
substrate that can be decorated.
Therefore a transfer foil with a toner receiving layer whereon
a toner image can be fixed and from which the image can be
transferred together with the toner receiving layer but where the
toner receiving layer is only transferred with the image and not
from the non-imaged parts of the foil, could solve both problems
referred to above. It would give a decorated substrate with a
toner image that is physically strong and with non impairing of the
surface of the substrate in the parts that do not bear an image.
It was found that such a toner receiving layer could be
produced when the receiving layer had a cohesive force (Fcoh) lower
than the force with which it adhered to the support (Frel) and when
this force (Frel) was in turn lower than the force with which the
toner particles adhered, after fixing, to the toner receiving layer
(Fton). When Fton < Frel, then in use of the transfer foil, the
toner particles will transfer alone, without taking the receiving
layer with them.
The cohesive force (Fcoh) of the toner receiving layer
determines the kind of break in the receiving layer : when this
force is rather low, then the layer breaks cohesively, i.e. part of
the layer stay on the support and some parts (in the case of the
toner receiving layer in an transfer foil of this invention, the
parts carrying the toner particles) are transferred to the
substrate to be decorated and the layer breaks at the boundary
between the toner bearing parts and the non-toner bearing parts.
The toner receiving layer, in a transfer foil according to this
invention, comprise a polymeric binder and the cohesive force of
this layer can be adjusted by adding a "promoter for cohesive
break" to the layer. The "promoter for cohesive break" is
preferable selected from the group consisting of spacing particles
with an average volume diameter dv50 ≥ 0.9d, waxes, polymers,
different from said polymeric binder and cross-linking agents for
said polymeric binder.
It is highly preferred to use a compound selected from the
group consisting of spacing particles with an average volume
diameter dv50 ≥ 0.9d and waxes as "promoter for cohesive break".
Examples of particulate materials useful for adding to the
image receiving layer to reduce cohesivity include inorganic
particles (e.g. calciumcarbonate, silica, talc, titan dioxide,
aluminium oxide) and organic particles, like particles of
poly(tetra-fluoroethylene, polymethylsilylsesquioxane (TOSPEARL,
trade name, available from Toshiba Silicone) and TEFLON MP (trade
name for particles with fluoro-additives available from du Pont).
The spacing particles for use as promoter for cohesive break are in
this invention are preferably polymeric spacing particles having F-atom
and/or Si-atoms at the surface and have preferably an average
volume diameter (dv50) that is at least 90 % of the thickness, d,
of the layer. More preferably, d ≤ dv50 ≤ 2.5d. When in a foil
according to this invention, spacing particles are used as
"promotor for cohesive break", it is preferred to use polymeric
particles of poly(methylsilylsesquioxane). E.g. polymeric
particles sold under trade name TOSPEARL, by Toshiba, Japan.
When in a foil according to this invention, spacing particles
are used as "promotor for cohesive break", the spacing particles
can be present in an amount between 1 and 50 % by weight (wt/wt)
with respect to the total weight of the toner receiving layer, the
spacing particles are preferably present in an amount between 5 and
25 % by weight (wt/wt) with respect to the total weight of the
toner receiving layer.
Waxes useful as promoter for cohesive break in a layer of this
invention, can be natural as well as synthetic waxes. Wax is a
technological collective word for materials that have "waxy"
behaviour. Compounds with "waxy" behaviour can best be described
by the physical properties of the compounds. In general the
greater number of waxes are characterised by the following criteria
:· they have a melting point of at least 40°C (this distinguishes
waxes from oils and fats), a relatively low melt-viscosity and when
molten they do not form strings like threads (this distinguishes
waxes from resins and plastics). "Waxy" compounds do not show
chemical transformation at elevated temperatures (this last
property is often cited as borderline between waxes and natural
resins). Waxes and wax-like materials, useful as cohesive break
promoter in an image receiving layer, of this invention, can be
selected from mineral waxes, natural waxes and synthetic waxes.
Examples of useful mineral waxes include petroleum waxes such as
paraffin wax, microcrystalline waxes, ester wax, oxidised wax,
montan wax, ozokerite and ceresine. Examples of useful natural
waxes include plant waxes such as carnauba wax and Japan wax, and
animal waxes such as bee wax, insect wax, shellac wax, spermaceti
wax and whale wax. Very useful synthetic waxes are generally a
higher aliphatic compounds such as higher aliphatic alcohols with
formula CH3(CH2)nCH2OH, wherein n ranges from 6 to 28 or higher
aliphatic acids with formula CH3(CH2)nCH2COOH, wherein n ranges
from 6 to 28. Also unsaturated higher aliphatic alcohols or acids
are useful as waxes in this invention. Further useful are, esters
of the above fatty acids, e.g., ethyl stearate, lauryl stearate and
ethyl behenate, amides of the above fatty acids : e.g. stearic acid
amide. Also dimethylglycolphthalate can be used. The above
mentioned waxes or wax like materials can be employed in the form
of a solution or dispersion (emulsion). Most preferably the wax
will be used as a waterborne or solvent based dispersion
(emulsion).
Also polymeric waxes are very useful as promotor for cohesive
break in a toner receiving layer on a foil according to this
invention. Very useful polymeric waxes for use as "promoter for
cohesive" break in this invention are compounds selected from the
group consisting of high density polyethylene waxes, polypropylene
waxes, polyvinylstearate, polyethylene sebacate, sucrose
polyesters, higher aliphatic alcohols with formula CH3(CH2)nCH2OH,
wherein n ranges from 20 to 300 or higher aliphatic acids with
formula CH3(CH2)nCH2COOH, wherein n ranges from 20 to 300 and
polyalkylene oxides. A very useful wax can be chosen from the
polypropylene waxes, sold under trade name CERIDUST by Hoechst,
Germany. Other waxes very useful as wax in a toner receiving layer
in a transfer foil of this invention are sold under trade name
UNILIN 450, UNILIN 700,( trade names of PETROLITE, 6910 East 14th
street, TULSA, Oklahoma 74112, USA for polyolefinic alcohols with
average molecular weight of 425, 700), UNITHOX 720, a trade name
for a hydroxyterminated, polyolefinic polyoxyethylenic
macromolecule, with average molecular weight of 875 of the same
PETROLITE company. and a monofunctional carboxyl terminated
polyolefine as UNICID 700, a trade name of PETROLITE for a
polyolefinic monocarboxylic acid with average molecular weight of
700.
Polymeric compounds useful as promoters for cohesive break can
be hydrophilic colloid materials, such as polyvinylalcohol,
gelatine, hydroxyalkylcellulose, polyvinylpyrrolidon, carboxymethylcellulose,
methylcellulose, polyethylene oxide and gum
Arabic. Other suitable polymers as promotor for cohesive break
comprise polydimethyl siloxane, methylphenylsilicone resin,
tetrafluoroethylene telomer (e.g. VYDAX -trade name of du Pont,
Wilmington, USA), organosilicon copolymer (e.g. SILWET L-7001 trade
name of Union Carbide), polyvinyl chloride and vinyl chloride
copolymers, polyvinylidene chloride and vinylidene chloride
copolymers, polyethylene and polypropylene, ethylene copolymers,
polystyrene, styrene copolymers. Also poly(meth)acrylates and
(meth)acrylate copolymers, polyamide resins such as alcohol-soluble
POLYAMIDE CM-8000 (trade name of Toray Co.,Ltd.), synthetic rubber,
chlorinated rubber, vinylacetate copolymers, polyvinyl acetal
resins, polyhydroxystyreen (e.g. RESIN M ; trade name of Maruzen
Co.,Ltd. Japan), can be used as promoter for cohesive break.
The image receiving layer in a transfer sheet according to this
invention, comprises preferably a polymer that has good film-forming
properties and that is transparent. A binder for the image
receiving layer is further chosen on the basis of the adherence of
toner particles to it, the ease with which such a layer is
separated from the support and/or from an intermediate release
layer on said support. In that case it is preferred that said
release layer stays, after transfer on the support and is in its
totality peeled away together with said support. It is preferred
to use a binder for the image receiving layer of a transfer sheet
of this invention that so that the cohesive properties of the that
that layer can easily be tuned so that after image-wise transfer of
the image, the receiving layer is image-wise transferred together
with the toner image and thus giving good physical properties
(scratch resistance, optical clarity, solvent-resistant, gloss,...)
to the transferred image. Examples of possible image receiving
polymers, chosen with regard to the demands outlined above, include
nitro-cellulose, polyvinylidene chloride and vinylidene chloride
copolymers, poly(meth)acrylates and (meth)acrylate copolymers,
(e.g. ELVACITE 2044, ELVACITE 2008 trade names of du Pont,
Wimington USA, PLEXIGUM M345 , trade name of Röhm and Haas,
Germany) modified hydroxy(meth)acrylates [e.g. JAGOTEX F 253, F 218
and F219, trade names of Ernst Jäger GMBH, Germany), polystyrene
and styrene copolymers, vinylacetate copolymers, polyvinyl acetal
resins (polyvinyl butyral or polyvinyl formal), polyester resins
(e.g. ALMACRYL EB56 trade name of Mitsui, Ltd, Japan). vinyl
choride/vinylacetate/vinyl alcohol-copolymer (e.g. UCAR VAGD trade
names of Union Carbide),polyvinyl acetate, styrene/maleicanhydride
copolymers (e.g. SCRIPTSET 540 trade name of Monsanto, USA),
polyvinylacrylates, polyvinyl chloride and vinyl chloride
copolymers, e.g., polyvinyl acetate/polyvinyl chloride copolymers
such as HOSTAFLEX CM131 trade name of Hoechst Celanese Corp, USA.
In a preferred embodiment the binder resin of a toner receiving
layer in a transfer foil of this invention comprises a polymer
selected from the group of homo-polymers of methylmethacrylate, copolymers
including methylacrylate moieties, co-polymers including
methylmethacrylate moieties, nitrocellulose being nitrated for at
most 12.5 mol %, polyvinylacetate and polyvinylbutyral.
Nitrocellulose being nitrated for at most 12.5 mol % is available
from Wolff Walsrode AG, Walsrode, Germany under trade names
Nitrocellulose TYPE A, 10.9 to 11.3 % nitration, TYPE AM, 11.4 to
11.7 % nitration and TYPE E, 11.8 to 12.2 % nitration.
The image receiving layer in a transfer sheet according to this
invention, may have a thickness of about 0,5 µm to about 10 µm.
More preferable the thickness is situated between 1 and 5 µm. The
toner receiving layer in a transfer foil according to this
invention can be a single layer, with a thickness as given above,
or a double or multiple layer if so desired, e.g., for enhancing
the coating quality (smoothness, avoiding of pin-holes, etc.).
When double or multiple layers are coated, the composition of the
respective layers can be equal or different. In this document the
layer or layers of the transfer foil whereon the toner particles
are deposited and fixed and that are transferred together with the
toner image when using the imaged transfer foil for decoration of
objects, is the toner receiving layer.
As already said above the image receiving layer in a transfer
sheet of this invention can, for enhancing the cohesive break, be
partially or wholly cross-linked. This cross-linking can be
obtained by chemical curing or by radiation curing.
Polymers containing a chemical reactive group such as a free
hydroxyl group, like vinyl acetal resins (e.g., polyvinyl butyral
or polyvinyl formal), present a point of chemical reactivity
through which the resins may be made insoluble. Any chemical
reagent or resinous material which reacts with secondary alcohols
will react with this kind of polymers to inhibit solubility and to
promote hardness. Possible cross-linking agents are e.g.
phenolics, epoxides, dialdehydes, di-or-poly-isocyanates and
melamines. Coating properties vary greatly with the type and amount
of cross-linking agent used. Polymers like modified hydroxy
(meth)acrylates (e.g. JAGOTEX F 253, F 218 and F219, trade names of
Ernst Jäger GMBH, Germany) or nitro-cellulose also result in good
cross-linking properties when hardened with aliphatic
di-or-poly-isocyanates. The curing process can be enhanced by the
presence of a catalyst. A variety of catalysts can be employed to
accelerate the speed of the reaction. Possible catalysts are e.g.
stannous octoate, zirconium octoate, bismuthstearate and lead
stearate.
Radiation (UV or EB) curable compositions containing
(meth)acrylic monomers or oligomers are also effective to improve
the cohesive break of the image receiving layer. UV-curable coating
can broadly classified into two categories: free radical
polymerised and cationic polymerised. The interest in cationically
cured compositions has grown the last years. Polymers formed by
free radical polymerisation are generally based upon acrylic or
methacrylic monomers or oligomers, which are converted to high
molecular weight polymers with varying degrees of cross-link
density upon exposure to ultraviolet radiation.
In a transfer foil according to this invention, when cross-linking
is used as means for controlling the cohesive break of the
imaging layer, it is preferred to use chemical cross-linking.
Preferably the transfer foil comprises a plastic (synthetic
polymer) support, e.g. polyester (polyethyleneterephthalate,
polyethylenenaphthalate, etc.), syndiotactic polystyrene,
polypropylene, etc. When a plastic support is used it is preferred
to use a thermoset polymeric foil, since during the fusing of the
toner image to the transfer foil, a quite high temperature can be
reached. This high temperature entails the risk of wrinkling or
wrapping up of the foil when the foil is not thermoset. A transfer
foil comprising a thermoset support has also the advantage that it
does not undergo large dimensional changes during the fusing step.
The support in a transfer foil according to this invention, is
preferably less than 75 µm thick, more preferably the thickness is
equal to or lower than 50 µm. The use of a thin support is
preferred because with a thin support the transfer foil can, after
being imaged, be used for decorating objects that are not flat,
because a thin support follows quite easily the contours of the
object to be decorated. Further, since the support of the transfer
foil is stripped away and has either to be recuperated or
discarded, the less material that is present, the better.
The imaging layer in a transfer sheet according to this
invention can be applied to directly to a support and the
releasability of said image receiving layer is secured by the fact
that the surface of the support, whereon the image receiving layer
is applied, is inherently releasable.
It is preferred in a transfer foil according to this invention
that the support is rendered releasable by a suitable treatment or
is provided with a release layer over the support surface. Such
release layers preferably stay integral with the support after the
image and the image-wise broken image receiving layer is
transferred. In this case, a transfer foil according to this
invention comprises in the order given a support with a thickness
equal to or lower than 75 µm, a release layer, adhering to said
support with a force FPET' and an image receiving layer with a
polymeric binder and having thickness d, a cohesive force Fcoh and
adhering to said release layer with a force Frela characterised in
that FPET > Frela > Fcoh. In this case, also, it is preferred that
force (Frela) was in turn lower than the force with which the toner
particles adhered, after fixing, to the toner receiving layer
(Fton). When Fton < Frela, then in use of the transfer foil, the
toner particles will transfer alone, without taking the receiving
layer with them.
The release layer may comprise hydrophilic colloid materials,
such as polyvinyl alcohol, gelatine, hydroxyalkyl cellulose,
polyvinylpyrrolidon, carboxymethylcellulose, methylcellulose,
polyethylene oxide, gum Arabic. Other suitable release layers
comprise polydimethyl siloxane, methylphenylsilicone resin,
tetrafluoroethylene telomer (e.g. VYDAX trade name of du Pont),
organosilicon copolymer (e.g. SILWET L-7001 -trade name of Union
Carbide), polyvinyl chloride and vinyl chloride copolymers,
polyvinylidene chloride and vinylidene chloride copolymers,
polyethylene and polypropylene, ethylene copolymers, polystyrene,
styrene copolymers, waxes and wax-like materials (see
above),poly(meth)acrylates and (meth)acrylate copolymers, polyamide
resins such as alcohol-soluble polyamide CM-8000 (trade name Toray
Co.,Ltd. Japan), synthetic rubber, chlorinated rubber, vinylacetate
copolymers, polyvinyl acetal resins, polyhydroxystyreen (e.g. RESIN
M ; trade name of Maruzen Co., Ltd.), chlorinated polyvinylchloride
(e.g., GENCLOR S, trade name of ICI LTD, UK).
The release layer may have a thickness of about 0,01 µm to
about 10 µm. Most preferably the release layer comprises a binder
selected from the group consisting of polyvinylpyrrolidon,
polyvinylalcohol, co-poly(vinylacetate-crotonic acid),polyvinyl
chloride, organo-silicon release polymers, waxes or wax-like
materials and polymethylmethacrylate.
Although in this document means for controlling the cohesive
break of a polymeric layer is described in relation to a toner
receiving layer in a transfer foil, it is clear that the means for
controlling cohesive break can successfully be incorporated in any
polymeric layer when cohesive break of that layer is desired.
Examples of materials comprising polymeric layers wherein cohesive
break is desired are, e.g., photodelamination materials based on
photopolymerisation, image recording material for image recording
by heat mode laser induced change in adhesion, etc..
Thus in an apparatus, for producing a master image according to
this invention, several means for image-wise or non-image-wise
applying of toner particles can be present and said means for
depositing toner particles can be direct electrostatic printing
means, wherein charged toner particles are attracted to the
substrate by an electrical field and the toner flow modulated by a
printhead structure comprising printing apertures and control
electrodes.
Said means for depositing toner particles can also be toner
depositing means wherein first a latent image is formed. In such
an apparatus, said means for depositing toner particles comprise :
- means for producing a latent image on a latent image bearing
member,
- means for developing said latent image by the deposition of said toner particles, forming a developed image and
- means for transferring said developed image on said substrate.
Said latent image may be a magnetic latent image that is
developed by magnetic toner particles (in magnetography) or,
preferably, an electrostatic latent image . Such an electrostatic
latent image is preferably an electrophotographic latent image and
the means for producing a latent image are in this invention
preferably light emitting means, e.g., light emitting diodes or
lasers and said latent image bearing member comprises preferably a
photoconductor.
An apparatus for forming a master images on a transfer foil
according to this invention, can be any apparatus for
electrostatographic, magnetographic imaging, whatever the toner
depositing means, both appartus adapted for monochromatic printing
and apparatus adapted for full-colour printing.
When full-colour toner images are to be printed on a transfer
according to this invention, typical examples of very useful
apparatus are a commercial CHROMAPRESS (a trade name of Agfa-Gevaert
NV, Mortsel, Belgium), used in simplex mode and wherein
five toner depositing station are present on one side of the image
receiving member (i.e. in this invention the temporary support
whereon the master image is formed), or an AGFA XC305 colour
copier. Also apparatus as disclosed in EP-A 742 496 or equivalent
co-pending US Serial Number 08/641,070 filed on April 29, 1996 and
in EP-A 742 497 or equivalent co-pending US Serial Number
08/636,829 filed on April 23, 1996, used in simplex mode are very
useful for producing a master image on a transfer sheet according
to this invention. When more toner layers are wished in the
master image than the number of toner depositing stations present
in the apparatus it is possible to print the master image in multi-pass.
An apparatus for producing a toner image on a transfer foil
according to the present invention, can comprise any fusing means
known in the art. The fusing means can combine heat and pressure,
radiant heat e.g. hot air, or infra-red radiation, etc. When using
fusing means combining heat and pressure, heated pressure rollers
can be used and silicone oil is used to impart release properties
to the rollers. When using such fusing means in an apparatus for
printing a toner image on a transfer foil according to this
invention, it is preferred to apply said silicone oil to said
rollers in such an amount that on top of the master image at most 1
g/m2 of silicone oil is present. Having more silicone oil can give
problems when transferring and adhering the master image to the
object to be decorated. It is preferred, in an apparatus for
printing a toner image on a transfer foil according to this
invention, to use fusing means using radiant heat, while in that
case no silicone oil at all is present on the master image.
For all examples of transfer sheets a clear
polyethyleneterephthalate support was used. The thickness was
between either 12 or 23 µm.
In part of the examples this support was used as such without
any treatment and the image receiving layer was coated directly on
that support. In further examples, the support was provided with a
subbing layer as known from the art of photography and a release
layer was applied to the support prior to applying the image
receiving layer.
The transfer sheets of all examples were single sided imaged in
a CHROMAPRESS (trade name) of Agfa Gevaert NV, Mortsel Belgium, on
the side carrying the image receiving layer. The developer used
was the commercially available developer containing magnetic
carrier particles coated with a silicone resin and toner particles
comprising a polyester as toner resin and a cyan pigment.
The ease and quality of transfer was tested by applying the
images on the transfer foil in contact with a surface of a sheet of
acrylonitrile-butadiene-styrene polymer (ABS) to be decorated.
An rectangular stamper with an even, siliconised rubber coated
surface with dimension 7 x 13 cm was used. The contact surface
between the stamper and the ABS surface was 70 cm2. The image and
the surface to be decorated were pressed together with a pressure
of 7.105 Pa for 2 seconds at 220 °C.
After cooling the support was peeled, away and the quality of
the decoration was judged on four properties :
- transfer of the image (TT)
- transfer of the image receiving layer (TIL)
- extent to which the image receiving layer was image-wise transferred together with the toner image (ITIL)
- the ease with which the support could be stripped away, i.e. the ease of release after transfer (RAT)
The four properties were evaluated on a scale from 0 to 4,
wherein 0 is very good, 1 is good, 2 is acceptable, 3 is barely
acceptable, and 4 is unacceptable.
All percents in the following examples are percents by weight
A solution of 25 g of polymethylmethacrylate (ELVACITE 2008
trade name of du Pont, Wimington USA) in 75 g methylethylketone
(MEK) as solvent was applied by gravure printing to an untreated
polyethyleneterephthalate support of 23 µm thick in such a way to
have a dry image receiving layer of 2 µm. The transfer sheet was
imaged and the image transferred as described above. The results
are tabulated in table 1.
Example 1 was repeated, except for the fact that the support
was 12 µm thick.
A solution of 9% polymethylmethacrylate (ELVACITE 2008 , trade
name of du Pont , Wilmington, USA) and 1% polypropylene wax
(CERIDUST F3910 , trade name of Hoechst, Germany) in MEK was coated
on a untreated polyethyleneterephthalate support of 12 µm thick
with a 20 µm coating knife. After drying the thickness of the dry
image receiving layer was 2 µm . The transfer sheet was imaged and
the image transferred as described above . The results are
tabulated in table 1 .
A solution of 10% polymethylmethacrylate (PLEXIGUM M345 , trade
name of Röhm & Haas Germany) in MEK was coated on a untreated
polyethyleneterephthalate support of 23 µm thick with a 20 µm
coating knife . After drying the thickness of the dry image
receiving layer was 2 µm . The transfer sheet was imaged and the
image transferred as described above .
The results are tabulated in table 1 .
A solution of 5 % polymethylmethacrylate (PLEXIGUM M345 , trade
name of Röhm & Haas, Germany) and 5% hydroxypropylcellulose (KLUCEL
LF , trade name of Hercules Inc., Wilmington, USA) in MEK/ethanol
(1/1) was coated on a untreated polyethyleneterephthalate support
of 23 µm thick with a 20 µm coating knife . After drying the
thickness of the dry image receiving layer is 2 µm . The transfer
sheet was imaged and the image transferred as described above .
The results are tabulated in tabel 1 .
A solution of 25 % of polymethylmethacrylate (ELVACITE 2008
trade name of du Pont, Wimington USA) and 2.5 % of particles with
silicone atoms at the surface (TOSPEARL 130 trade name of Toshiba
Corp, Japan for particles made of poly(methylsilylsesquioxane) in
methylethylketone (MEK) as solvent was applied by gravure printing
to an untreated polyethyleneterephthalate support of 23 µm thick in
such a way to have a dry image receiving layer of 2 µm.
The transfer sheet was imaged and the image transferred as
described above .
The results are tabulated in tabel 1 .
A solution of 15 % polyvinylpyrrolidone in ethanol as solvent
was coated on a polyethyleneterephthalate support of 12 µm thick
with a subbing layer so has to form a release layer of 1 µm thick.
On top of this release layer, a solution of 25 % of
polymethylmethacrylate (ELVACITE 2008 trade name of du Pont,
Wimington USA) and 2.5 % of particles with silicone atoms at the
surface (TOSPEARL 130 trade name of Toshiba Corp, Japan for
particles made of poly(methylsilylsesquioxane) with an average
particles diameter of 3 µm) in methylethylketone (MEK) as solvent
was applied by gravure printing in such a way to have a dry image
receiving layer of 2 µm.
The transfer sheet was imaged and the image transferred as
described above. The results are tabulated in table 1.
A solution of 15 % polyvinylpyrrolidone in ethanol as solvent
was coated on a polyethyleneterephthalate support of 12 µm thick
with a subbing layer so has to form a release layer of 1 µm thick.
On top of this release layer, a solution of 25 g of
polymethylmethacrylate (ELVACITE 2008 trade name of du Pont,
Wimington USA) in 75 g methylethylketone (MEK) as solvent was
applied by gravure printing in such a way to have a dry image
receiving layer of 2 µm. The transfer sheet was imaged and the
image transferred as described above. The results are tabulated in
table 1.
On top of a release a in example 8, a solution of 9%
polymethylmethacrylate (ELVACITE 2008 , trade name of du Pont ,
Wilmington, USA) and 1% polypropylene wax (CERIDUST F3910 , trade
name of Hoechst, Germany) in MEK was coated with a 20 µm coating
knife. After drying the thickness of the dry image receiving layer
was 2 µm . The transfer sheet was imaged and the image transferred
as described above . The results are tabulated in tabel 1 .
A solution of 15% polyvinylpyrrolidone and 3 % of amorphous
silica particles with particle size dv50 = 4 µm in ethanol as
solvent was coated on a polyethyleneterephthalate support of 23 µm
thick with a subbing layer so has to form a release layer of 1 µm
thick.
On top of said release layer a solution of 25 g of
polymethylmethacrylate (ELVACITE 2008 trade name of du Pont,
Wimington USA) in 75 g methylethylketone (MEK) as solvent was
applied by gravure printing in such a way to have a dry image
receiving layer of 2 µm. The transfer sheet was imaged and the
image transferred as described above. The results are tabulated in
table 1.
A solution of 1.44 g of polyamide (CM-8000,, trade name of
Toray Ltd. Japan) 0.36 g of polyhydroxystyrene (RESIN M trade name
of Maruzen Co., Japan) in 80 g of methanol and 20 g of
methylcellosolve, were coated on a subbed polyethyleneterephthalate
support with thickness 123 µm so as to from a release layer with
thickness 1 µm.
On top of this release layer a solution of 20 g
polyvinylbutyral (BUTVAR B79, trade name of Monsanto Company, USA),
6 g of
(DESMODUR N3300 trade name of Bayer AG, Leverkusen, Germany)
and 3 g of dibutyl-Sn-dilaurate in 157 g of methylethylketone was
coated so as to form a dry image receiving layer of 2 µm. The
material was dried for 2 hours at 100 °C so that the image
receiving layer was chemically cured. The transfer sheet was imaged
and the image transferred as described above. The results are
tabulated in table 1.
Example # | Thickness support in µm | Relaese layer | Image receiving layer | ||||
E1 | 23 | NO | 0 | 0 | 1 | 1-2 | |
E2 | 12 | NO | 0 | 0 | 3 | 1-2 | |
E3 | 12 | NO | / | 2-3 | 4 | 4 | |
E4 | 23 | NO | 0 | 0 | 3 | 1-2 | |
E5 | 23 | NO | / | 3 | 2 | 1 | 1-2 |
E6 | 23 | NO | / | 0 | 0 | 0 | 1-2 |
E7 | 12 | YES | / | 0 | 0 | 0 | 0-1 |
E8 | 23 | YES | 0 | 0 | 3 | 0-1 | |
E9 | 12 | YES | A/ | 0 | 0 | 0 | 0-1 |
E10 | 12 | YES | 0 | 0 | 0 | 0-1 | |
E11 | 23 | YES | PVB/ | 0 | 0 | 0 | 0-1 |
Claims (13)
- A transfer foil comprising a support with a thickness equal to or lower than 75 µm and, directly adjacent to said support, an image receiving layer with a polymeric binder and having thickness d, a cohesive force Fcoh and adhering to said support with a force Frel characterised in that Frel > Fcoh.
- A transfer foil comprising in consecutive order a support with a thickness equal to or lower than 75 µm, a release layer, adhering to said support with a force FPET , and an image receiving layer with a polymeric binder and having thickness d, a cohesive force Fcoh and adhering to said release layer with a force Frela characterised in that FPET > Frela > Fcoh.
- A transfer foil according to claim 1 or 2, wherein said image receiving layer comprises a promoter for cohesive break of said imaging layer selected from the group consisting of spacing particles with an average volume diameter dv50 ≥ 0.9d, waxes, polymers, different from said polymeric binder and cross-linking agents for said polymeric binder, and wherein said promoter for cohesive break of said imaging layer is present in said layer in an amount between 1 and 50 % by weight with respect to said polymeric binder.
- A transfer foil according to any of claims 1 to 3, wherein said polymeric binder in said image receiving layer comprises a polymer selected from the group of homo-polymers of methylacrylate, homo-polymers of methylmethacrylate, co-polymers including methylacrylate moieties, co-polymers including methylmethacrylate moieties, nitrocellulose being nitrated for at most 12.5 mol %, polyvinylacetate and polyvinylbutyral.
- A transfer foil according to any of claims 1 to 4, wherein said promotor for cohesive break are polymeric spacing particles selected from the group of polymeric particles having superficial F-atoms and polymeric particles having superficial Si-atoms.
- A transfer foil according to any of claims 2 to 5, whereinsaid release layer contains a polymer selected from the group consisting of polyvinylpyrrolidon, polyvinylalcohol, co-poly(vinylacetate-crotonic acid),polyvinyl chloride, organosilicon release polymers, waxes or wax-like materials and polymethylmethacrylate.
- A transfer foil according to any of claims 2 to 6, whereinbetween said support and said release layer a subbing layer containing a polymer selected from the group of vinylidenechloride polymers, polyesters and addition polymers with itaconic acid moieties, is present andsaid subbing layer adheres to said support with a force FPETa and said release layer adheres to said subbing layer with a force Fhech.
- A toner image having toner particles fixed on a transfer foil according to claim 1, wherein said toner particles adhere to said image receiving layer with a force Fton such that Fton > Frel > Fcoh.
- A toner image having toner particles fixed on a transfer foil according to claim 2 whereinsaid toner particles adhere to said image receiving layer with a force Fton such that Fton > Frela > Fcoh.
- A toner image having toner particles fixed on a transfer foil according to claim 7 whereinsaid toner particles adhere to said image receiving layer with a force Fton such that Fton > Frela > Fcoh, FPETA > Frela > Fcoh.and Fhech > Frela > Fcoh.
- A method for decorating a surface of an object comprising the steps ofimage-wise depositing toner particles on a transfer foil with a support and an image receiving layer according to any of claims 1 to 7,fixing said toner particles to said transfer foil, forming a toner image,contacting said toner image with said surface to be decorated and heating the transfer foil, and peeling said support away, whereinsaid image receiving layer is image-wise transferred to said substrate together with said toner image.
- A method according to claim 11, wherein said toner particles are image-wise deposited by a digital electrostatographic printing system by unwinding said transfer foil as a web from a roll.
- method according to claim 11, wherein said toner particles have a melt viscosity η such that 100 Pas ≤ η ≤ 2000 Pas and an elasticity (Tg δ-1) > 0.1.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97203814A EP0921441A1 (en) | 1997-12-04 | 1997-12-04 | A transfer foil for use in electrostatographic printing |
US09/188,299 US6156416A (en) | 1997-12-04 | 1998-11-10 | Transfer foil for use in electrostatographic printing |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97203814A EP0921441A1 (en) | 1997-12-04 | 1997-12-04 | A transfer foil for use in electrostatographic printing |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0921441A1 true EP0921441A1 (en) | 1999-06-09 |
Family
ID=8229017
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97203814A Withdrawn EP0921441A1 (en) | 1997-12-04 | 1997-12-04 | A transfer foil for use in electrostatographic printing |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0921441A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110229819A1 (en) * | 2010-03-19 | 2011-09-22 | Konica Minolta Business Technologies, Inc. | Method of foil transfer employing foil transferring face forming toner and image forming method |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0094845A2 (en) * | 1982-05-18 | 1983-11-23 | Esselte UK Limited | Transfer imaging systems |
JPS59174680A (en) * | 1983-03-24 | 1984-10-03 | Fuji Xerox Co Ltd | Adhesive paper |
-
1997
- 1997-12-04 EP EP97203814A patent/EP0921441A1/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0094845A2 (en) * | 1982-05-18 | 1983-11-23 | Esselte UK Limited | Transfer imaging systems |
JPS59174680A (en) * | 1983-03-24 | 1984-10-03 | Fuji Xerox Co Ltd | Adhesive paper |
Non-Patent Citations (1)
Title |
---|
DATABASE WPI Section Ch Week 8447, Derwent World Patents Index; Class A12, AN 84-284637, XP002062456 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110229819A1 (en) * | 2010-03-19 | 2011-09-22 | Konica Minolta Business Technologies, Inc. | Method of foil transfer employing foil transferring face forming toner and image forming method |
US9034553B2 (en) * | 2010-03-19 | 2015-05-19 | Konica Minolta Business Technologes, Inc. | Method of foil transfer employing foil transferring face forming toner and image forming method |
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