TRANSFER PAPER FOR TRANSFERRING IMAGES TO SUBSTRATES

Description

[0001] The present invention relates to a system for transferring images to substrates (transfer printing), such as textile backings, in particular T-shirts. The invention also relates to a corresponding method for transferring images to solid materials.

[0002] During transfer printing, i.e. the transfer of images onto substrates such as textile backings using so-called transfer papers onto which the image to be transferred is applied in advance, under increased pressure and temperature conditions, undesirable background transfer often occurs, namely the transfer of parts of the coating of the transfer paper which are not part of the image.

[0003] To prevent this, additional work steps such as contour cutting on the transfer paper and subsequent weeding are necessary and / or different temperatures must be used when preparing the transfer paper and during the actual transfer process.

[0004] Particularly with dark substrates, such as dark-colored or black textiles, the color of the transferred image, in particular the strength and brilliance of the colors, is not satisfactory when using the single-sheet systems available on the market, which are generally produced for light-colored textiles.

[0005] Another criterion is the wash resistance of the transferred image on the substrate, which is often unsatisfactory.

[0006] The currently known solutions for transferring without a background onto "dark-colored and black" substrates and fabrics with a correspondingly good strength, brilliance of the colors and good wash resistance are currently limited exclusively to so-called two-sheet systems.

[0007] A two-sheet system for transferring images to substrates is known, comprising a printable carrier (component A) comprising the image in the form of an at least partial toner layer, and a component B comprising a carrier and a polymer layer arranged thereon and a further opaque layer (WO 2013 / 159922 A1). This system is a "self-weeding" system, with essentially only the printed areas being transferred to the substrate without the need for contour cutting and weeding. However, a disadvantage is that two different sheets must be handled, and the transfer process requires two steps under elevated temperature and pressure conditions, as well as an additional separation step for components A and B.

[0008] The image is advantageously applied to the carrier material / transfer paper by means of digital printing, laser printing, in particular by means of (color) copiers or (color) laser printers, inkjet printers, using commercially available inks or toners.

[0009] The present invention therefore has for its object to provide a simplified system and method for transferring images to substrates that overcomes the above-mentioned disadvantages.

[0010] The present invention therefore relates to a transfer paper for transferring images to substrates, comprising a support with one or more wax coatings; a layer (A) arranged thereon, containing a wax emulsion, a binder, an inorganic crystalline substance and a pigment; a layer (B) arranged on the layer (A) containing an organic polymer, in particular a polydiallyldimethylammonium chloride, a binder, a fixing agent, a copolymer and a pigment; a layer (C) arranged on the layer (B) containing an organic polymer, in particular a polydiallyldimethylammonium chloride, a wax emulsion, a copolymer, an inorganic crystalline substance and a pigment.

[0011] US 2003 / 021962 A1 describes an ink-jet printable transfer paper comprising a carrier with a silicone coating, a washing layer arranged thereon and an ink-receiving layer arranged thereon.

[0012] US 2003 / 0219575 A1 relates to a transfer paper comprising a carrier, a polymer release layer and an ink receiving layer.

[0013] US 2011 / 0162789 A1 relates to a transfer paper comprising a carrier, a wax layer, a first thickener layer on the wax layer and a second thickener layer on the first thickener layer.

[0014] The present invention represents a one-sheet solution for light-colored and especially dark-colored, as well as black substrates, in particular dark-colored and black textiles, fabrics and solids.

[0015] The invention provides a so-called self-weeding single-sheet system, wherein the transfer paper is printed with an image to be transferred, the printed transfer paper is placed with the printed side on a substrate, the substrate with the transfer paper arranged on it is exposed to the effects of pressure and temperature, e.g., using a thermal transfer press or an iron, and the transfer paper is peeled off the substrate in such a way that the unprinted areas remain on the paper carrier and the printed areas, i.e., the image, remain on the substrate. The carrier is peeled off in a warm or hot state (so-called "warm peel" or "hot peel"). Warm peeling means that peeling occurs after a waiting time following the transfer process. The waiting time is typically up to approximately 15 seconds. Hot peeling means that peeling occurs directly after the transfer process.The peeling / separation therefore takes place essentially in the range of the temperature of the pressing process or slightly lower, in particular above room temperature.

[0016] The present invention is particularly suitable for the transfer of images onto dark substrates, such as dark or black textiles.

[0017] The image is applied to the transfer paper using conventional printing methods, advantageously digital printing, laser printing, in particular using (color) copiers or (color) laser printers, inkjet printers, whereby commercially available inks or toners are advantageously used.

[0018] Suitable inks for the purposes of the present invention include water-soluble or solvent-based inks, sublimation inks, polymer inks, so-called flexographic inks, screen printing inks, offset inks, or the like. Sublimation inks are preferably used for applying the image to the transfer paper.

[0019] Toners consist of the corresponding color pigments in a plastic matrix, usually made of polyester with a melting range of approximately 80-120°C, for example, and possibly additional additives. The thickness of the toner layer is within the usual technical values and is typically 5-50, preferably 5-20 g / m² (based on basis weight).

[0020] Carriers for transfer papers are known per se and can be made from nonwovens, particularly those based on cellulose fibers, such as coated or uncoated paper or cardboard, or from plastic films. The carrier is, for example, a film, cardboard, or paper, in particular a paper with a basis weight of, for example, approximately 80-150, preferably approximately 90-100 g / m², such as a machine-smooth paper suitable for (color) copiers, (color) laser printers, or inkjet printers.

[0021] At least one surface of said carrier or paper is provided with a polymer coating (hereinafter also referred to as wax layer) made of polyolefins, polyolefin copolymers or polyurethanes with a layer thickness of approximately 20 - 60, preferably approximately 25-50 g / m 2<.

[0022] Polyolefins used include, for example, LDPE optionally with maleic anhydride, EVA with approx. 7-28%, preferably approx. 7-15% VA content, ethylene-acrylic acid copolymers or ethylene-methylacrylate copolymers with approx. 5-12% acrylic acid, ethylene-butyl-acrylate copolymers with approx. 5-20% acrylate, which preferably have a melt index according to ASTM-D-1238 (MFI) of approx. 3.5-22, preferably approx. 7-15 g / 10 min at 2.16 kg / 190°C.

[0023] The layer preferably contains wax. Suitable waxes include paraffins or paraffin waxes, or mixtures of paraffin waxes with LDPE. These waxes typically have melting points in the range of approximately 60-100°C. In particular, a wax layer can be additionally arranged between the carrier surface and the extrusion layer, typically having a layer thickness of approximately 10-20 g / m².

[0024] The wax layer can be single-layered or multi-layered. The wax layer is preferably multi-layered.

[0025] Methods for changing the surface structure of the carrier, e.g. by treating the surface with profile rollers or similar, are also familiar to the person skilled in the art.

[0026] To improve the wettability of the surface and the adhesion of the inks or toners, the surface of the carrier can optionally be subjected to a further surface treatment to increase the surface tension, in particular a plasma or corona treatment is carried out according to the invention.

[0027] A layer (A) is arranged on the wax coating of the carrier, which comprises the following ingredients (percentages refer to wt.% based on the total weight of the layer): a wax emulsion, in particular based on polyethylene wax. The proportion of the wax emulsion is typically approximately 15-40%, in particular approximately 20-30%; a polyurethane-based binder for elasticity. The proportion of the binder is typically approximately 40-70%, in particular approximately 40-60%; an inorganic crystalline substance, such as, in particular, silica, but also calcium carbonate or bentonite. The proportion of the inorganic crystalline substance is typically approximately 5-35%, in particular approximately 10-25%; a pigment, advantageously in an acrylate-based binder. The proportion of the pigment is typically approximately 15-40%, in particular approximately 20-35%.

[0028] The pigment is organic and / or inorganic and selected from white pigments, color pigments, glitter, metallic pigments, functional pigments, or mixtures thereof. For example, the pigment can be selected from several color pigments.

[0029] The white pigment composition preferably contains approximately 25-75% of a white pigment, for example, titanium dioxide, chalk, barium sulfate, zinc sulfide, zinc sulfate, or kaolin, preferably titanium dioxide, and approximately 25-75% of a plastic binder, which can be a polyolefin, polyolefin copolymer, or polyurethane, with reference to the above list of possible substances. Alternatively, a color pigment or functional pigment can also be used.

[0030] Functional pigments are pigments with reflective, phosphorescent, fluorescent, photoluminescent or similar optical properties.

[0031] The layer thickness of the A layer is approximately 2 - 15 g / m 2< , preferably approximately 4-10 g / m 2< , in particular approximately 2 - 6 g / m 2< , especially approximately 7 - 15 g / m 2< .

[0032] The A layer advantageously has glass transition or softening temperatures in the range of approximately 130 - 200°C.

[0033] Layer (A) essentially serves to provide the basic color. This is especially important when one or more color pigments are included. Especially in the case of monochrome images, layer (A) then serves to provide the basic color of the image.

[0034] On top of layer (A) there is a layer (B) which comprises the following ingredients (percentages refer to % by weight based on the total weight of the layer): an organic polymer, in particular based on diallylmethylammonium chloride (polydiallyldimethylammonium chloride), which serves in particular to bind the color pigments. The proportion of the organic polymer is typically approx. 5-30%, in particular approx. 10-25%; a binder, in particular based on polyurethane, for elasticity. The proportion of binder is typically approx. 5-30%, in particular approx. 10-25%; a fixative, in particular based on polyurethane, for improving wash resistance. The proportion of fixative is typically approx. 1-20%, in particular approx. 5-15%; a copolymer, in particular based on vinyl acetate and ethylene, for absorbing the ink and drying it. The proportion of copolymer is typically approx. 10-35%, in particular approx. 15-30%. a pigment, in particular in an acrylate-based binder. The proportion of organic or inorganic pigment is typically approx. 25-50%, in particular approx.30-45%.

[0035] Optionally, additives such as an inorganic crystalline substance, e.g., silica or cellulose ester, or other known processing aids can be added. Preferably in a proportion of approximately 5-35%, more preferably 10-30%.

[0036] Further components that may be included are: a plastic, particularly suitable are polyesters, polyurethanes, polyacrylates and other compounds, for example homo- or copolymers of vinyl acetate, vinyl alcohol, vinyl chloride, vinylidene chloride, methyl and / or ethyl acrylic acid or methacrylic acid, maleic acid compounds, styrene, etc.

[0037] Also suitable are cellulose esters and cellulose ethers such as ethyl cellulose, benzyl cellulose, cellulose propionates or acetates or butyrates or polyesters of terephthalic acid or polyamides such as nylon or Perlon.

[0038] The pigment is organic and / or inorganic and selected from white pigments, color pigments, glitter, metallic pigments, functional pigments, or mixtures thereof. For example, the pigment can be selected from several color pigments.

[0039] The layer thickness of the B layer is about 5 - 20 g / m 2< , preferably about 10-15 g / m 2< , in particular about 5 - 12 g / m 2< , especially about 13 - 20 g / m 2< .

[0040] The B layer advantageously has glass transition or softening temperatures in the range of approximately 130 - 200°C.

[0041] The layer (B) essentially serves functionally to absorb the ink, in particular the color particles after sublimation of the ink, and to improve the wash resistance and elasticity of the image on the substrate.

[0042] Another function of layer (B) is good adhesion to layer (A).

[0043] On top of layer (B) there is a layer (C) which comprises the following ingredients (percentages refer to wt.% based on the total weight of the layer): an organic polymer, in particular based on diallylmethylammonium chloride, which serves in particular to bind the color pigments. The proportion of the organic polymer is typically approximately 10-40%, in particular approximately 15-30%; a wax emulsion, in particular based on polyethylene wax. The proportion of the wax emulsion is typically approximately 15-40%, in particular approximately 20-35%; a copolymer, in particular based on vinyl acetate and ethylene, for absorbing the toner or ink and drying it. The proportion of copolymer is typically approximately 15-40%, in particular approximately 20-35%; an inorganic crystalline substance, such as in particular silica, but also calcium carbonate or bentonite. The proportion of the inorganic crystalline substance is typically approximately 5-30%, in particular approximately 10-25%; a pigment, in particular in an acrylate-based binder. The pigment content is typically approximately 10-35%, especially approximately 15-30%.

[0044] The pigment is organic and / or inorganic and selected from white pigments, color pigments, glitter, metallic pigments, functional pigments, or mixtures thereof. For example, the pigment can be selected from several color pigments. The pigment is advantageously a white pigment.

[0045] The layer thickness of the C layer is about 5 - 20 g / m 2< , preferably about 10-15 g / m 2< , in particular about 5 - 12 g / m 2< , especially about 13 - 20 g / m 2< .

[0046] The C layer advantageously has glass transition or softening temperatures in the range of approximately 130 - 200°C.

[0047] Layer (C) is the printable layer onto which the image is applied. Its functional purpose is essentially to absorb the ink, particularly the color particles after sublimation of the ink, and to adhere them to the substrate.

[0048] Further functions of layer (C) are good adhesion to layer (B) and covering of the substrate color.

[0049] In the case of monochrome images, the pigments in layer (A) are preferably selected from color pigments, thus determining the base color of the image. It is advantageous for the pigments in layers (A) and (B) to be selected from color pigments of the same color. By specifying the base color of the image, the color of the ink is of secondary importance in this case. A transparent ink or toner could even be used.

[0050] The pigment in layer (C) is preferably a white pigment. This serves to provide basic coverage of the substrate's color. Furthermore, a metallic pigment can also be added for better coverage of the substrate surface.

[0051] In the case of colored images, the pigments in layers (A), (B), and (C) are preferably white pigments. The ink, especially the color particles after sublimation of the ink, penetrate all layers (A) - (C) and produce a colored image on the substrate.

[0052] According to the invention, further optional layers can be present. For example, it is possible to have two layers (B) instead of one layer (B), or two layers (C) instead of one layer (C). Advantageously, in this case, the two layers (B) or (C) each individually have a smaller layer thickness than in the case of only one layer (B) or (C).

[0053] It is also possible to have an optional layer (D), e.g. a metal layer made of metallic pigments, which is arranged above layer (C) and thus represents the outermost layer of the transfer paper.

[0054] During production, the respective layers are preferably applied separately one after the other to the carrier, in particular with sufficient drying times.

[0055] Layers (A), (B) and (C), possibly further optional layers, can be formulated in such a way that they are activated by an alcoholic-aqueous fluid, such as the liquid phase of the ink, or by a melting toner under increased pressure and temperature, but the layer structures are essentially retained.

[0056] Without being bound to any theory, it is assumed that the self-weeding process of the printed transfer paper is caused by the outermost layer of the transfer paper, typically layer (C), becoming sticky due to interaction with the toner or ink under pressure and temperature. Under these conditions, a melting toner or the solvent-based medium of an ink will at least partially dissolve layer (C), thus causing it to stick to the substrate surface.

[0057] Layer (C) adheres to the substrate surface. The formulation of the layers causes a certain degree of brittleness in the printed area when exposed to heat, so that when the carrier (backing paper) is peeled off, a type of vertical break occurs in the layer sequence (i.e., from layer (C) towards layer (B), layer (A), and possibly the wax layer) along the printed area. Thus, layers (B) and (A), and possibly parts of the wax layer, are held to the substrate by layer (C), while no adhesion to the substrate occurs in the unprinted area.

[0058] The present invention also relates to the use of the transfer paper according to the invention.

[0059] Another object of the present invention is a method for transferring images to a substrate using the transfer paper according to the invention.

[0060] The method according to the invention for transferring images to substrates comprises providing a transfer paper according to the invention; applying the image to layer (C) by means of a printing process, advantageously by means of digital printing, whereby printed and non-printed areas are defined on layer (C); applying the transfer paper to a substrate with the printed side (layer (C)) facing the surface of the substrate; subsequent pressing of the arrangement of substrate and transfer paper at approximately 2 - 5 bar in the temperature range from a minimum of approximately 100 - 150°C to a maximum of approximately 200 - 250°C, for example from approximately 100 - 250°C, in particular from approximately 150°C to a maximum of approximately 200 - 250°C, in particular from approximately 150 - 220°C, in particular from approximately 150 - 200°C, also 180 - 220°C, typically for a minimum of approximately 15 - 20 seconds to a maximum of approximately 60 seconds, in particular approximately 15 - 45 seconds, preferably 15 - 30 seconds, whereby the image is transferred to the substrate; and separating the carrier of the transfer paper in the warm or hot state.

[0061] The process according to the invention can be carried out using conventional devices, so-called transfer presses.

[0062] According to one embodiment of the invention, after the image has been transferred to the substrate, the image is subjected to additional treatment. This is preferably a so-called finishing process, in particular by applying a finishing foil, such as hot stamping foil or flock sheet. The use of such foils in the field of transfer printing is familiar to those skilled in the art (https: / / www.forever-ots.de / produkt / hot-stamping-foils / ; https: / / www.plottermarie.de / folien / 825-veredelungsfolien-meterware.html; https: / / www.printequipment.de / heisspraege / ; https: / / lfp-partner.eu / datenblatt / forever / HSF-Anleitung-DE.pdf; https: / / www.forevertransferpaper.com / no-cut-flock-sheets).

[0063] The hot stamping foil is typically applied at temperatures in the range of approximately 150 to 200°C and medium to high pressures of approximately 3 to 6 bar, preferably high pressures of approximately 5 bar, for approximately 10 to 120 seconds, preferably approximately 25 to 45 seconds. The hot stamping foil is typically removed while cold.

[0064] Therefore, a combination of the transfer paper according to the invention with a finishing film is also possible. The combination can be provided in a spatially separate form or in a common packaging.

[0065] Unless otherwise stated or the context dictates otherwise, percentages refer to the weight, or in case of doubt to the total weight of the mixture.

[0066] The invention also relates to all combinations of preferred embodiments, provided they are not mutually exclusive. The invention is defined by the claims. The terms "about" or "approx." in conjunction with a numerical value mean that values that are at least 10% higher or lower, or 5% higher or lower, and in any case 1% higher or lower are included. Where an indefinite article such as "a," "an," or "an" is used above in reference to a term, this also includes the meaning "one or more" or "at least one."

Claims

1. Transfer paper for transferring images onto substrates, comprising a carrier, wherein at least one surface of said carrier being provided with a polymer coating, also referred to as a wax layer, of polyolefins, polyolefin copolymers or polyurethanes with a layer thickness of about 20 - 60 g / m2; (A) a layer arranged thereon with a layer thickness of about 2 - 15 g / m2, containing a wax emulsion, a binding agent, an inorganic crystalline substance, such as in particular silica but also calcium carbonate or bentonite, and a pigment; (B) a layer arranged on layer (A) with a layer thickness of about 5 - 20 g / m2, containing an organic polymer, in particular based on diallylmethylammonium chloride, a binding agent, a fixing agent, a copolymer and a pigment; (C) a layer arranged on layer (B) with a layer thickness of about 5 - 20 g / m2, containing an organic polymer, in particular based on diallylmethylammonium chloride, a binding agent, an inorganic crystalline substance, such as in particular silica but also calcium carbonate or bentonite, a wax emulsion, a copolymer and a pigment, wherein the pigment in layers (A) - (C) is organic and / or inorganic and is selected from white pigment, colour pigments, glitter, metal pigments, functional pigments or mixtures thereof.

2. Transfer paper according to claim 1, wherein the carrier is selected from paper, foil or cardboard.

3. Transfer paper according to claim 1 or 2, wherein the pigment is present in an acrylate-based binding agent.

4. Transfer paper according to claim 1, wherein the pigment in layer (A) is a white pigment or one or more colour pigments.

5. Transfer paper according to one of claims 1 to 4, wherein the organic polymer in layer (B) and / or (C) is a polydiallyldimethylammonium chloride.

6. Transfer paper according to one of claims 1 to 5, wherein layer (B) additionally contains an inorganic crystalline substance.

7. Transfer paper according to claim 1, wherein the surface of the carrier is subjected to a further surface treatment to increase the surface tension, in particular a plasma or corona treatment.

8. Transfer paper according to claim 1, wherein the polymer coating is wax-containing.

9. Method for transferring images onto substrates, comprising - providing a transfer paper according to one of claims 1 - 8; - applying an image onto the layer (C) by means of a printing process, wherein printed and non-printed areas are defined on the layer (C); - applying the transfer paper onto a substrate with the printed side (layer (C)) facing the surface of the substrate; - subsequently pressing the arrangement of substrate and transfer paper at about 2 - 5 bar in the temperature range from a minimum of about 100 - 150°C to a maximum of about 200 - 250°C, for example from about 100 - 250°C, in particular from about 150°C to a maximum of about 200 - 250°C, in particular from about 150 - 220°C, in particular from about 150 - 200°C, also 180 - 220°C, typically for a minimum of about 15-20 seconds to a maximum of about 60 seconds, in particular about 15 - 45 seconds, preferably 15 - 30 seconds, wherein the image is transferred onto the substrate; and - separating the carrier of the transfer paper in the warm or hot state.

10. Use of the transfer paper according to one of claims 1 to 8 for transferring images onto substrates, in particular dark-coloured or black textiles.