EP3302991A2 - Transfer material for sublimation printing - Google Patents

Abstract

The invention relates to a transfer material for the dye-sublimation transfer method of an ink jet printing image, comprising a support and an ink receiving layer on the front side of the transfer material, wherein the ink-receiving layer is porous and the transfer material contains a barrier layer which is disposed either on the rear side of the transfer material or between the support and the porous ink-receiving layer.

Description

 Transfer material for sublimation printing

TECHNICAL FIELD OF THE INVENTION

The invention relates to a sheet-like transfer material for the dye sublimation transfer process of an inkjet print image with a support and a color receiving layer on the front side. Consequently, it relates in particular to a transfer paper which is provided for printing with sublimable dyes by the inkjet printing process and from which, after printing, the dyes are transferred under heat to a receiving material by sublimation. The invention also relates to the transfer method using the transfer material.

TECHNICAL BACKGROUND OF THE INVENTION For printing on materials such as textiles or rigid bodies, which are difficult to print by direct printing methods for mechanical reasons, transfer printing methods are suitable in which a flexible sheet-like transfer material is first printed and the printed image is printed on the latter

is transferred to the printing object. A particular embodiment of such a transfer printing process is the dye sublimation process, which is described in U.S. Pat

Example in B. Thompson: Printing Materials - Science and Technology (1998) on page 468 is described. In this method, the image to be printed on the

Transfer material applied using printing inks, which are evaporated after the drying of the pressure under the action of heat and imagewise on the gas phase on the final material to be printed again. The sublimation inks can be advantageously applied to the transfer material by digital printing, in particular the inkjet printing process, which allows individual and personalized prints, for example on textiles. Drucktit Inkjet printing processes with dyes which can be transferred to the final print substrate by sublimation are described, for example, in DE 102 46 209 A1. The transfer material on which the first printing step takes place by means of inkjet printing technology is preferably a paper transfer material. In EP 1 101 682 Al a coated paper is described which has a low air permeability on the side to be printed. This is to avoid that in the

Sublimation transfer step, a portion of the sublimable dyes penetrate into the porous paper interior and thus lost for transfer to the final print material. However, such papers with a low porosity on the page to be printed take up the inkjet ink liquid only very slowly and lead to a slow drying and bleeding of the ink on the surface and thus to an unsatisfactory printing sharpness, especially at high printing speeds.

EP 2743091 A1 describes a transfer material and proposes to coat a less air-permeable substrate with a hydrophilic polymer or a salt of a hydrophilic polymer. The coating may also contain an inorganic oxide filler as filler in amounts of up to 10% by weight. Such

 Coating solutions always form a polymer film which may have voids at low application rates and rough substrates. Fast absorption and drying of ink applied by inkjet printing with sublimable dyes is not achieved.

It was therefore in the US 2008/229962 AI a coating for a

Transfer paper is proposed, which contains silica and a relatively small amount of binder and thus has a considerable air permeability. Thus, a recording of the ink liquid is achieved, but it is not a loss of sublimable dye in the paper inside during transfer to the final material to be printed prevented. SUMMARY OF THE INVENTION

The invention has for its object to provide a transfer paper for the inkjet printing of sublimable dyes that a fast

 Drying and high pressure sharpness in the use of aqueous printing inks and at the same time a substantially complete transfer of

ensures sublimable dyes on the final material to be printed and has little or no penetration of the sublimable dyes on the back of the transfer paper.

This object is achieved by a transfer material for the dye sublimation transfer method of an inkjet print image with a carrier and a

Ink receiving layer on the front side of the transfer material, wherein the

Ink receiving layer is porous and the transfer material includes a barrier layer, which is disposed either on the back of the transfer material or between the support and the porous ink-receiving layer.

The barrier layer can be arranged either between the porous ink-receiving layer and the paper carrier or on the surface of the paper carrier opposite the ink-receiving layer.

The invention further relates to a method for transferring an image to a surface by printing an inventive transfer material with an image by the ink-jet printing process and transfers the image by sublimation on the surface.

DETAILED DESCRIPTION OF THE INVENTION

The transfer papers according to the invention comprise a paper support having a porous ink-receiving layer applied on the pressure side and a barrier layer, which is disposed between the ink receiving layer and the paper support and / or preferably on the opposite side of the ink receiving layer surface of the paper support. The backing paper is preferably an uncoated or surface sized paper. The backing paper can be next to pulp fibers, sizing agents such as

Alkylkene dimers, fatty acids and / or fatty acid salts, epoxidized fatty acid amides, alkenyl or alkyl succinic anhydride, starch, tree resins, wet strength agents such as polyamine-polyamide-epichlorohydrin, dry strength agents such as anionic, cationic or amphoteric polyamides, optical brighteners, pigments, dyes, defoamers and others in the paper industry may contain known chemical additives. The base paper can be surface-sized. For this purpose, suitable sizing agents are

for example, polyvinyl alcohol or oxidized starch. The base paper can be produced on a Fourdrinier or a Yankee paper machine (cylinder paper machine). The basis weight of the base paper may be 30 to 200 g / m ² , in particular 40 to 120 g / m ² . The raw paper can be used in uncompacted or compacted form (smoothed). Particularly well suited

Base papers with a density of 0.6 to 1.05 g / cm ³ , in particular 0.70 to 0.9 g / cm ³ . The smoothing can be done in the usual way with a calendering.

For papermaking it is possible to use all pulps customary for this purpose. The pulp for papermaking is preferably a eucalyptus pulp with a pulp content of less than 200 μm after grinding of 10 to 35% by weight and an average fiber length of 0.5 to 0.75 mm. It has been shown that the use of a pulp with a limited proportion of fibers less than 200 μιτι reduces the stiffness loss occurring when using filler.

Hardwood pulps (NBHK - Northern Bleached Hardwood Kraft Pulp) and softwood pulps may also be used. In addition to pulp fibers, it is also possible to use fractions of other natural or synthetic fibers for the production of

Carrier papers are used. Preferably, the proportion of other fibers on the total fiber mass below 40 wt .-%, particularly preferred are proportions of other fibers below 20 wt .-%.

As fillers for sheet production, for example, kaolins, calcium carbonate in its natural form such as limestone, marble or dolomite stone, precipitated calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, silica,

Alumina and mixtures thereof are used in the base paper. Particularly suitable is calcium carbonate with a particle size distribution in which at least 60% of the particles are smaller than 2 μιτι and at most 40% are smaller than 1 μηι. In a particular embodiment of the invention calcite is used with a numerical particle size distribution, in which about 25% of the particles a

Particle sizes of less than 1 μηι and about 85% of the particles have a particle size of less than 2 μιη. According to another embodiment of the

Invention, a calcium carbonate can be used with a numerical particle size distribution, wherein at least 70%, preferably at least 80% of the

Particles are smaller than 2 μιη and at most 70% of the particles are smaller than 1 μιη.

One or more further layers may be arranged between the carrier paper and the ink receptive layer and / or barrier layer. Preferably, this involves a hydrophilic binder-containing layers.

The dye-receiving layer, which is arranged on the side to be printed on the carrier paper, according to the invention is porous. It preferably contains inorganic pigment and binder. Particular preference is given to inorganic pigments having an anionic, neutral or only weakly cationic surface, such as silica,

Calcium carbonate, kaolin, talc, bentonite or aluminum oxides or

Aluminiumoxdidhydrate. However, it may also contain finely divided polymeric compounds, with high-melting thermoplastic or thermosetting polymers are preferred. In a further embodiment of the invention, the ink receptive layer may also be a mixture of two or more pigments contain. The pigments preferably have an average particle size of 100 nm to 30 μηι, more preferably from 200 nm to 10 μηι.

The dye-receiving layer preferably additionally contains a polymeric binder, preferably a hydrophilic polymeric binder. The binder may be a water-soluble or water-dispersed binder. preferred

Binders are styrene copolymers, polyvinyl alcohol, starch, modified starch, polyvinyl acetate, acrylates or polyurethane dispersoids. The mass ratio of pigment to binder is 100: 1 to 100: 50, preferably 100: 40 to 100: 2.

The dye-receiving layer is preferably prepared by application of an aqueous

Spreading applied to the paper carrier, whereby all customary in the paper industry application method can be used. Particularly preferred is an application by means of blade, doctor blade, film press or curtain casting.

The coating composition may contain other conventional additives such as wetting agents, thickeners, rheology aids, dyes and optical brighteners. The

Coating weight of the dye-receiving layer is preferably 1 g / m ² to 50 g / m ² , more preferably 3 g / m ² to 30 g / m ² . The air permeability of the

Color receiving layer, measured according to Bendtsen, is greater than 100 ml / min, preferably 200 ml / min to 700 ml / min. The dye-receiving layer has pores which may have an average pore diameter of 10 nm to 5 μν, preferably from 100 nm to 1.5 μηι and particularly preferably from 500 nm to 1 μηι. Of the

Pore diameters of porous dye-receiving layers can be determined by mercury porosimetry. The method of mercury porosimetry for

Determination of pore diameters is described, for example, in M.J. Mouraa, P.J. Ferreirab, M.M. Figueiredob: Mercury intrusion porosimetry in pulp and paper technology, Powder Technology, 160 (2), p 61-66 (2005). For the purposes of

In the present invention, the mercury porosimetry for determining the pore size of the dye-receiving layer was carried out with the porosimeter PASCAL 440 from Porotec / Thermo Fisher Scientific. Between the ink receiving layer and the paper carrier and / or on the back of the paper carrier, a barrier layer is arranged according to the invention. The

Barrier layer is characterized by a low permeability to air and gases as well as water vapor. The air permeability of the barrier layer, measured according to Bendtsen, is less than 100 ml / min, preferably less than 10 ml / min. The barrier layer preferably contains one or more polymeric compounds. In one embodiment of the invention, the barrier layer contains one or more thermoplastic polymers, wherein high-melting thermoplastic polymers such as polyester or polymethylpentene are particularly preferred. In this

 Embodiment, the barrier layer can be applied by the melt extrusion coating method.

In a particularly preferred embodiment of the invention, the

Barrier layer formed by applying an aqueous solution or an aqueous dispersion of one or more water-soluble or water-dispersed polymers. Preferred polymers are styrene copolymers, polyvinyl alcohols or polyvinyl acetate. In a further preferred embodiment of the invention, the barrier layer contains polymers based on renewable raw materials, such as starch, modified starch and / or cellulose derivatives, for example

Carboxymethylcellulose (CMC).

The coating weight of the barrier layer is preferably 1 g / m ² to 40 g / m ² , more preferably 2 g / m ² to 20 g / m ² .

The transfer material according to the invention is particularly suitable for transferring a printed image onto a surface selected from polyester fabric, polyester nonwoven fabric, a surface coated with a polyester layer or a polyester surface.

The following examples serve to further illustrate the invention. EXAMPLES

1. Preparation of a Carrier Paper A eucalyptus pulp was used to produce the carrier paper. to

Grinding the pulp was ground as about 5% aqueous suspension (thick stock) with the aid of a refiner to a freeness of 26 ° SR. The concentration of

Pulp fibers in the thin was 1 wt .-%, based on the mass of

Pulp suspension. The thinner added further additives such as a neutral sizing agent alkyl ketene dimer (AKD) in an amount of 0.23 wt .-%,

Wet strength agents polyamine-polyamide-epichlorohydrin resin (Kymene ^®) in an amount of 0.60 wt .-%, starch (C-Bond HR 35845] in an amount of 1.0 wt .-%, and a natural ground CaC0 ₃ in an amount of 15% by weight. The amounts given refer to the pulp mass.

The thinstock, whose pH was adjusted to about 7.5, was transferred from the head box to the wire of the paper machine, followed by sheet formation by dewatering the web in the wire section of the paper machine. In the press section, the further dewatering of the paper web to a water content of 60 wt .-%, based on the web weight. Further drying took place in the dryer section of the

Paper machine with heated drying cylinders. The result was a base paper with a basis weight of 90 g / m ² , a filler content of 10 wt .-% and a humidity of about 5.5%. The base paper is surface-sized on both sides in a size press containing 3% by weight C-Film 05731 starch from Cargill and water. The amount of starch applied on both sides is about 1.5 g / m ² . After this

Thickness, the vehicle paper is again dried and smoothed. The carrier paper thus obtained has an air permeability, measured according to the Bendtsen method according to DIN 53120-1, of 700 ml / min. 2. Preparation of a coating composition for the dye-receiving layer

To 208 g of a diluted dispersion of precipitated calcium carbonate (Precarb ^® 724 of Schaefer Kalk) having a solids content of 45 wt .-% slowly 13 g of a precipitated silica (manufactured by Grace CP510) and 134 g of an aqueous 10 are wt .-% Solution of a fully saponified polyvinyl alcohol (Mowiol ^® 28-99 Kuraray) was added and the mixture is mixed with a dissolver stirrer. Thereafter, 1.5 g of wetting agent Surfynol® 440 Air Products is admixed. The coating slip obtained has a solids content of 34% by weight and a pH of 7 to 8. The average pore diameter of one of this coating slip

produced layer, measured by mercury porosimetry, is 750 ± 50 nm.

3. Preparation of a coating composition for the barrier layer To 1,000 g of an aqueous solution of 10 wt .-% fully hydrolyzed polyvinyl alcohol (Mowiol ^® 28-99) are 4g surfactant Surfynol ^® 440 from Air Products were added.

4. Comparison material VI

The reference material used is a commercially available transfer material with a release and barrier layer (Transjet Classic 831-100 g / m ² ). This comparative material has no porous coating on the pressure side.

5. Production of a transfer paper without barrier layer (comparison V2)

It is applied to the carrier paper prepared according to Example 1, the coating composition of Example 2 with a knife and dried. The dry application is 15 g / m ² .

6. Preparation of a transfer paper with a barrier layer between

Ink receiving layer and backing paper (Invention El) On the carrier paper of Example 1, the coating composition for the barrier layer of Example 3 is applied with a doctor blade and dried. The dry application was 5 g / m ² . Subsequently, the coating composition from Example 2 is applied to the barrier layer thus obtained using a doctor blade and dried. The dry application of this layer is 20 g / m ² .

7. Preparation of a transfer paper with ink receiving layer on the front side and a barrier layer B2 on the back side of the backing paper (invention E2). The coating paper is applied to the backing paper prepared in example 1

Example 2 applied with a doctor and dried. The dry application is 15 g / m ² . On the thus obtained barrier layer opposite side of the

Carrier paper, the coating composition for the barrier layer of Example 3 was applied with a doctor blade and dried. The dry application was 5 g / m ² .

test methods

The resulting transfer materials were printed with a color image using the inkjet printer EPSON WP4015 with Sublijet IQ sublimation inks from Sawgrass.

Drying after inkjet printing was evaluated by two test methods: a) smearfastness: After a defined time (fresh, 30sec, 1min, 3min, 5min), the finger is used to print over 4 full-color printing fields in the colors cyan, magenta, Yellow and black painted and the smearing of the colors rated.

Abklatschtest: The printed full color areas CMYK are brought into direct contact immediately after printing with the back of a second sheet of the transfer material and pressed with a 5kg roller (Cobb roller). It is then visually assessed how much color has been transferred to the back of the second sheet.

Transfer of the printed image to a textile fabric by sublimation:

In a transfer press Rotex Autoswing X from Sefa, the image side of the printed transfer material is brought into contact with a Berger-Backlight satin FR + w polyester fabric, on the back side of the transfer material is additionally a sheet of office paper with a basis weight of 80 g / m ² for evaluation the color breakdown inserted. At a temperature of 200 ° C, a level 30 contact pressure is applied for 30 seconds according to the height indicator scale of the press. Thereafter, the tissue and the copy paper of the

 Transfer material separated.

The print definition is visually and with a microscope both on the

 Transfer material evaluated before the image transfer as well as after the sublimation transfer on the fabric. The color density is measured for the full color fields CMYK with a spectrophotometer SpectroEye from X-rite.

The color bleed is visually evaluated on the basis of the color transferred in the sublimation transfer operation on the backside inserted copy paper. Table - Test results for VI. V2. El and E2

and copy)

 Print-

Line Sharpness + / + +++ / +++ ₊₊ / ₊ +++ / +++

Before and after

 sublimation

Transfer to the

 tissue

 Transferred +++ ++ +++ ++

color density

 Color breakdown +++ - ++ +++

The test results of the table show that the inventive

Transfer materials have a very good drying behavior after inkjet printing, show a high line sharpness even in the image transferred to the tissue, transfer the sublimation dye in the Sublimationsübertagungsvorgang highly to the tissue and give very little dye through the back.

The pore size was determined using a porosimeter PASCAL 440 from Porotec / Thermo Fisher Scientific. Mercury was used as the pressure medium. The sample weight was 1.0 g, the maximum pressure was 400 MPa and the temperature was 22.7 ° C.

Claims

Patent claims A transfer material for the dye sublimation transfer method of an inkjet print image having a support and a dye receiving layer on the front surface of the transfer material, characterized in that the  Ink receiving layer is porous and the transfer material includes a barrier layer, which is disposed either on the back of the transfer material or between the support and the porous ink-receiving layer. 2. Transfer material according to claim 1, characterized in that the carrier is a paper carrier. 3. Transfer material according to claim 1 or 2, characterized in that the porous ink-receiving layer has an air permeability according to Bendtsen of greater than 100 ml / min. 4. Transfer material according to one of claims 1 to 3, characterized in that the porous ink receiving layer has an average pore diameter of 10 nm to 5 μιτι. 5. Transfer material according to one of claims 1 to 4, characterized in that the barrier layer is arranged on the side facing away from the ink receiving layer of the paper carrier. 6. Transfer material according to one of claims 1 to 5, characterized in that the barrier layer has a Bendtsen air permeability of less 100 ml / min, in particular less than 50 or 20 ml / min. Transfer material according to one of claims 1 to 6, characterized in that the surface of the ink receiving layer is anionically charged or neutral. Transfer material according to one of claims 1 to 7, characterized in that the ink receiving layer has a pH at the surface of at least 7.0. The transfer material according to any one of claims 1 to 8, characterized in that the ink receiving layer contains a pigment selected from calcium carbonate, kaolin or silica. Transfer material according to one of claims 1 to 9, characterized in that the barrier layer contains a water-soluble polymer. Transfer material according to claim 10, characterized in that the water-soluble polymer is a polyvinyl alcohol, starch, modified starch or a cellulose derivative. Transfer material according to one of claims 1 to 11, characterized in that the barrier layer has a basis weight of 2 g / m ² to 20 g / m ² . Transfer material according to one of claims 1 to 12, characterized in that the basis weight of the ink receiving layer is 3 g / m ² to 30 g / m ² . Method of transferring an image to a surface, thereby characterized in that a transfer material according to any one of claims 1 to 13 is printed with an image by the ink-jet printing process and transmits the image by sublimation on the surface. A method according to claim 14, characterized in that the surface is selected from polyester fabric, polyester nonwoven, one with a Polyester layer coated surface or polyester surface.