Ink-jet transfer system for dark textile substrates

Abstract

An ink-jet transfer system is disclosed, as well as a transfer printed product which is highly wash-resistant, color-fast and environment-friendly, and a process for producing the same and its use in a printing process by means of the disclosed ink-jet transfer system. The disclosed ink-jet transfer system has a substrate, a hot-melt layer applied on the substrate and at least one ink-absorbing layer which comprises a mixture of a highly porous pigment and a binder. The molecules of the pigment and if required of the binder and hot-melt layer can form chemical bonds with the dyeing molecules of the ink.

Claims

1. An article for imparting an image to a dark-colored receiving member, comprising: a carrier paper including a release enhancing coating; and one or more layers overlaying the release-enhancing coating, the one or more layers comprising an ink receptive layer, at least one polymer layer, and a white pigment; wherein the ink receptive layer is effective for receiving indicia; and wherein one of said polymer layers comprises a background layer including a polymer and a concentration and configuration of the white pigment sufficient to provide a substantially opaque background for the received indicia, the polymer being non-fusible at temperatures up to about 220 C.

2. The article of claim 1, wherein the at least one polymer layer further includes a hot-melt adhesive layer which is disposed between the release-enhancing coating and the ink receptive layer.

3. The article of claim 1, wherein the ink receptive layer includes polyamide.

4. The article of claim 2, wherein the hot melt adhesive layer comprises LDPE, EAA, or polyamide.

5. The article of claim 1, wherein the carrier paper is peelable away from the ink receptive layer and the at least one polymer layer along a portion of the release-enhancing coating.

6. An article for transferring an image to a fabric material, comprising: a removable carrier member; a substantially opaque white layer overlaying a portion of the carrier member, the opaque white layer having a melting range not within hand iron pressing temperatures and including a binder and a white pigment; and at least one ink-receptive layer overlaying the opaque white layer, the at least one ink-receptive layer including a binder and a polymeric material; wherein the at least one ink-receptive layer includes a first ink-receptive layer and a second ink-receptive layer.

7. The article of claim 6, wherein the at least one ink-receptive layer includes a melting temperature within a range of about 120 C. to about 180 C.

8. The article of claim 6, wherein the carrier member is coated with a release-enhancing coating.

9. The article of claim 8, wherein the release-enhancing coating comprises silicone.

10. An article for imparting an image to a receiving member, comprising: a carrier member; a substantially opaque first layer overlaying the carrier member, the opaque first layer including a white pigment and wherein the substantially opaque first layer is non-fusible up to about 220 C.; and a second layer overlaying the opaque first layer and configured to receive indicia, the second layer including a polymeric material.

11. The article of claim 10, wherein the substantially opaque first layer includes a concentration and configuration of the white pigment sufficient to provide a substantially white background to received indicia.

12. The article of claim 10, wherein the second layer is an ink-receptive layer.

13. The article of claim 11, wherein the received indicia is applied using an ink jet printer.

14. The article of claim 10, further comprising a hot-melt third layer disposed between the carrier material and the opaque first layer.

15. The article of claim 14, wherein the third layer comprises at least one of polyethylene, or ethylene acrylic acid.

16. The article of claim 10, wherein at least one of the opaque first layer or the second layer includes a binder.

17. The article of claim 10, wherein the opaque first layer includes a melt temperature not within hand iron pressing temperatures.

18. The article of claim 10, wherein the white pigment comprises at least one of zinc oxide, zinc sulfate, barium sulfate, or titanium oxide.

19. The article of claim 10, wherein the polymeric material of the second layer includes a polyamide.

Description

MODES FOR CARRYING OUT THE INVENTION

(1) In a preferred embodiment, the ink-receiving layer of the inventive ink-jet transfer system is composed of a highly porous pigment and a binder, whereby at least one of the two components, in particular the pigment being present in bigger amounts has available reactive amino groups that are capable of forming essentially covalent bonds to the dyestuff molecules of the liquid ink.

(2) In a particularly preferred embodiment of the present invention, the ink-receiving layer comprises a highly porous polyamide pigment and a binder composed of a soluble polyamide, whereby the terminal, free amino groups of the polyamide pigment and of the polyamide binder are capable of fixing reactive groups, for example sulfonate groups or carboxylate groups of the dyestuff molecules. Because of that, with the pigment component as well as the binder component, a chemical fixation of the dyestuff molecules can be achieved.

(3) Besides the inventive requirement of the capability of the formation of essentially covalent bonds between the dyestuff molecules of the ink and the molecules of the pigment as well as the binder, the ink-jet transfer system according to the present invention has to have a high absorption capacity or uptake, respectively, of ink in order to guarantee a clear print image. This requirement is achieved by providing a pigment, preferably a polyamide pigment with a high porosity.

(4) Preferred polyamide pigments which are used for the ink-jet transfer systems according to the present invention preferably display a spherical, for instance a globular geometry and an interior surface which is as high as possible. The granular sizes of the used polyamide pigments are in a range of about 2 m and about 45 m, whereby a range of 2 to 10 m is particularly preferred. The bigger the granular size of the polyamide pigments, the more the surface of said pigments is closed and thus the ink-receiving capacity is reduced or even rendered impossible, respectively. The interior surface of the highly porous pigment amounts to at least about 15 m.sup.2/g; preferably it is between about 20-30 m.sup.2/g.

(5) It turned out that in particular a polyamide pigment with the trade name Orgasol displays the required properties, in particular the high-grade porosity.

(6) A highly porous polyamide pigment with an interior surface of at least about 15 m.sup.2/g and a granular size of about 2 m and about 45 m is obtained by means of an anionic polyaddition and a subsequent controlled precipitation process. In contrast to the conventional production methods in which a polyamide condensation product, for example as a granulate, is prepared, which is then milled, the polyamide pigments are actually grown and the growth of the pigments is ceased upon reaching the desired granular size. 85-95% of the polyamide pigments thus obtained show the desired form and granular size, whereby only maximally 15% have a smaller or bigger granular size.

(7) For an ink-receiving layer with highly porous polyamides being used as pigments, the binder preferably is composed of a polyamide as well. The polyamide used as a binder is different concerning its properties from the polyamide pigment insofar as it is employed as a solution and thus does not have to comply with specific form requirements. The use of polyamide as a binder is therefore less critical. It has only to be soluble in a suitable solvent, for instance alcohol or a alcohol-water mixture, respectively, and preferably has available free terminal amino groups by means of which dyestuff molecules, for example sulfonate groups of azo-dyestuffs or ester groups can be fixed.

(8) The ratio of the highly porous pigment and the binder in the ink-receiving layer of the inventive ink-jet transfer system amounts to between about 5:1 and 1:1, preferably 3:1 and 2:1 and very much preferred 2.4:1.

(9) The hot-melt layer which is preferably used in the ink-jet transfer system according to the present invention as adhesive layer is found directly on the removable carrier material and serves to transfer the graphic presentation imprinted by the ink-jet printer on the textile substrate and to ensure an adhesion to the white background layer. Said transfer is, for instance, effected by a cold copy, i.e. by ironing on, cooling down and removing the carrier layer (baking paper). During the ironing on, the hot-melt layer and the ink-jet receiving layer, but not the white background layer are molten. This way, the image imprinted on the ink-receiving layer is transferred on the textile substrate without any fusing-associated distortions.

(10) The hot-melt preferably used as adhesive layer in contrast to the highly porous pigment, binder as well as the background layer, is essentially wax-like, i.e. it can be fused. Usually, hot-melts melt in a range of about 100-120 C. while the highly porous pigments preferably melt in a range of 120-180 C., preferably 140-160 C. A usual hot-melt is for instance an ethylene acrylic acid copolymer dispersion.

(11) Further additives can be contained in the ink-jet transfer system according to the present invention, however, upon the use of such additives, it has to be paid attention that their use does not impair the washproofness of the eventually obtained transfer print. Because of process-technology reasons, for instance, it is reasonable to use a dispersing additive for organic pigments in the preparation of the inventive ink-jet transfer system.

(12) As a support (cover layer) for the cold copy, nearly any separating paper can be used, preferably a heat-resisting paper, for example a silicone paper is used.

(13) Besides the ink-jet transfer system itself, an additional aspect of the present invention is a method for its preparation. The coating method comprises the following steps:

(14) a) application of an adhesive layer, preferably a hot-melt layer, which has dispersed spherical polyester particles of a granular size of less than 30 m onto a carrier material, for instance silicone paper, by means of a coating means for instance a coating machine, whereby a layer thickness of about 30 to 40 m is adjusted, thereafter drying the hot-melt layer, and

(15) b) application of a white background layer composed of elastic plastics which are non-fusible at ironing on temperatures (i.e. up to about 220 C.), and which are filled with white, preferably inorganic, pigments onto the hot-melt layer, preferably with a resulting layer thickness of about 20-35 m,

(16) c) application of at least one ink-receiving layer dispersion onto the white background layer, and

(17) d) drying the ink-jet transfer system.

(18) The double/multiple application of the ink-receiving layer according to step c) provides the advantage that a smooth and even surface as well as an ink-receiving layer with a balanced thickness is formed, whereby the printing process or the resulting print image, respectively, is influenced in a positive way.

(19) First, the graphic presentation to be applied onto the textile substrate is laterally correctly printed onto the ink-jet transfer system thus obtained by a usual printer, e.g. an ink-jet printer (ink-jet-plotter), cut out, removed from the support (e.g. silicone paper), covered with baking paper and afterwards ironed onto the desired textile substrate, for instance a T-shirt, at a temperature of between about 160 and 220 C., preferably of 170 C., during at least 10 seconds. The lowest layer is the carrier material which is removed and discarded before the application of the graphic presentation. As the preferred cover paper, a heat-resistant silicone paper (baking paper) is used. The printed graphic presentation obtained in such a way (cold copy) is smooth and faint.

(20) In the following, the present invention shall be illustrated by two examples whereby the examples are not to be construed as limiting the scope of protection.

Example 1

(21) Preparation of an Ink-Jet Transfer System

(22) In a first step, the hot-melt layer is applied onto a carrier material: Thereby, a silicone paper of a layer thickness of about 0.1 mm is coated with an ethylene acrylic acid copolymer containing dispersed spherical polyester particles of a granular size of between 5-25 m. The ratio of ethylene acrylic acid copolymer and spherical polyester particles is about 60:40 and the resulting layer thickness of the hot-melt layer is about 30 m.

(23) Subsequently, a white background layer (polyurethane foil) with a thickness of about 40 m containing about 15 weight-% TiO.sub.2 is applied onto the silicone paper coated with the hot-melt.

(24) On said elastic background layer of polyurethane/TiO.sub.2 a dispersion containing the ink-receiving layer is applied in two steps. In the first step, a layer thickness of 15 m is applied and in the second step, a layer thickness of 15 m is applied, whereby a total layer thickness of the ink-receiving layer of 30 m results.

(25) The ink-receiving layer was previously prepared as follows: an ethanol/water mixture in the ratio of 3:1 is placed in a vessel and a soluble polyamide binder is dissolved therein under heating to 45 C. Afterwards the highly porous polyamide pigment Orgasol 3501 EX D NAT1 with a granular size of 10 m as well as an interior surface of about 25 m.sup.2/g pigment is dispersed in the solution.

(26) In order to stabilize the dispersion, a dispersing additive for organic pigments commercialized by the Company Coatex with the product designation COADIS 123K is introduced and the dispersion is stirred during 10 minutes at room temperature.

(27) On the coating machine, the solvent is allowed to evaporate in order to obtain a solid ink-receiving layer on which the desired graphic presentation can be printed by means of an ink-jet printer.

(28) The desired foils can be cut arbitrarily according to the required needs.

Example 2

(29) Use of an Ink-Jet Transfer System for Printing

(30) The ink-jet transfer system prepared in example 1 is used in order to print a graphic presentation on a T-shirt. Thereby, in a first step, the desired electronically processible and stored graphic presentation is printed by a computer by means of an ink-jet printer in a laterally correct way onto the sheet which has been obtained as the ink-jet transfer system in example 1.

(31) Afterwards, the print is removed and put with the white side onto the desired side of the selected T-shirt and ironed on by means of a hot iron (baking paper+temperature of about 190 C.) during 10 seconds. Afterwards, the T-shirt thus processed is cooled down to about room temperature and the baking paper, i.e. the silicone paper is removed. The image thus obtained is shining and matt.

(32) While in the present invention, preferred embodiments of the invention are described, it has clearly to be pointed out that the invention is not limited thereto and may be otherwise practiced in the scope of the following claims.