STAMPING PRINTING PROCESS BY IMAGE TRANSFER WITH SPECIALLY COATED PAPER AND SUBLIMATION INK

Abstract

The present invention is a press-printing method for image transfer with a specially coated paper and sublimation ink, in which a pattern or image is printed on a paper coated with the special coating for subsequent transfer to the object to be printed. When used in an ink jet printing, screen printing, gravure printing or flexographic printing process, the coating prevents the printed ink from permeating the paper due to paper porosity. The image transfer from the coated paper to the object to be printed is performed by pressure and heat at a temperature between 200 C. and 230 C., wherein the coating is activated by the heat, so that the coating becomes soft and adjusts to the printing surface and is easily adhered to it. This allows a direct transfer of the sublimation ink to the contact area of the surface to be printed, which makes the coating superior to other coatings on the market.

Claims

1. A coated paper for use in image transfer in a press printing process, wherein the coated paper has a paper layer and a coating with a composition of 93 wt. % to 98 wt. % corn dextrin, 0.2 wt. % to 0.5 wt. % soda, 1 wt. % to 3 wt. % borax and 1 wt. % to 2 wt. % sodium chloride, wherein the coating composition has a viscosity between 3000 and 6000 CP and is arranged in a layer with a surface weight of 8 g/m.sup.2 to 12 g/m.sup.2 on the paper layer, wherein the paper layer has a surface weight of 50 g/m.sup.2 to 80 g/m.sup.2 and residual moisture of the coating is in a range of 5 wt. % to 7 wt. %.

2. The coated paper according to claim 1, wherein the composition is 95.5 wt. % to 96.5 wt. % corn dextrin, 0.35 wt. % to 0.45 wt. % soda, 1.9 wt. % to 2.1 wt. % borax and 1.5 wt. % to 1.7 wt. %, sodium chloride.

3. The coated paper according to claim 1, wherein the corn dextrin is modified corn dextrin.

4. A press printing process for image transmission with the coated paper according to claim 1 and sublimation ink, wherein an image is applied on the coated paper through a printing process and the image is transferred from the coated paper to the object to be printed by the action of pressure and heat at a temperature of 200 C. to 230 C.

5. The press printing process according to claim 4, wherein the residual moisture in the coated paper and coating, when the image is printed on an object, is caused by the heat to evaporate in fractions of a second, so that the coating is activated in such a way that it becomes soft and adjusts to the structure of the object to be printed, thereby covering a surface of the object to be printed, which is in contact with the coating, wherein the coating is subsequently dried by the heat, so that it is easily attached to the surface of the object to be printed.

6. The press printing process according to claim 5, wherein the object to be printed has a fabric structure on the surface to be printed, so that, when the coating is activated and softens, it adjusts to the fabric structure, so that the top of each fabric fiber that is in contact with the coating is covered and the coating is fixed to the fabric so as to easily adjoin.

7. The press printing process according to claim 4, wherein any image or pattern with sublimation ink is applied to the coated paper using inkjet, silkscreen, gravure or flexographic printing, and stably fixed on the coating surface.

8. The press printing process according to claim 4, wherein due to the application of the coated paper in the press printing process, no preshrinking process of the object to be printed is carried out in the run-up to the image transfer.

9. The press printing process according to claim 6, wherein in the fabric structure, each fiber is at least partially enveloped with the coating during image transfer from the coated paper, so that the sublimation ink is in direct contact with the fibers, such that the printed fabric structure of the object to be printed presents defined edges, contours, color gradients and color contrasts.

10. The coated paper according to claim 1, wherein the composition is 96 wt. % corn dextrin, 0.4 wt. % soda, 2 wt. % borax and 1.6 wt. % sodium chloride.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 shows the situation of the image transfer from a coated paper to the object to be printed with a coating according to prior art;

[0020] FIG. 2 shows the situation of the image transfer from a coated paper to the object to be printed with a coating according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0021] In order that the invention may be better understood and evaluated, it is described in detail below. It should be noted, however, that the described embodiment of the invention can be altered or modified by a man skilled in the art without leaving the scope of protection of the present invention.

[0022] According to the present invention, a special paper coating is created to solve the above mentioned problems and to provide an improvement of the resolution of the image fixed to the substrate (especially for fabrics). The coating may have the following composition: [0023] 1. 93 to 98 wt. % modified corn dextrin, preferably about 96 wt. %, [0024] 2. 0.2 to 0.5 wt. % soda, preferably about 0.4 wt. %, [0025] 3. 1 to 3wt. % borax, preferably about 2 wt. %, [0026] 4. 1 to 2 wt. % sodium chloride, preferably about 1.6 wt. %.

[0027] The modified corn dextrin is a corn dextrin modified by starch, in particular pre-gelled starch. Especially, the modified corn dextrin may be a mixture of Vegecol 10A (trade name, Supplier: PolyamidesBrazil) and Penetrose 80 (trade name, Supplier: Ingredion Incorporated, Brazil), whereby the Vegecol 10A may be present in a quantity of 80 to 95 wt. % and the Penetrose 80 in a quantity of 5 to 20 wt. %.

[0028] The above-mentioned coating composition, with a viscosity between 3000 and 6000 CPs (Centipoise, where 1 CP=1 MPa s), is applied with a surface weight of 8 g/m.sup.2 to 12 g/m.sup.2 on a paper layer with a surface weight of 50 g/m.sup.2 to 80 g/m.sup.2. The residual moisture of the coating is in a range between 5 wt. % and 7 wt. %.

[0029] The coating of the paper can be done by applying the following procedures: painting, spraying, in particular with an air knife, gravure rollers or similar.

[0030] In the case of a continuous coating in a coating machine, the metering rate can be between 80 m/min and 100 m/min and the drying in an oven may be performed at a temperature between 100 C. and 120 C. Maintaining the residual moisture is of fundamental importance in this production process, since the residual moisture of the composition activates the coating when heated so that the coating 1 contour-faithfully covers the fibers 2 of the fabric (FIG. 2) and adheres to them so that the sublimation can take place direct contact and not only at the points of contact (FIG. 1), as currently with commercial coatings 3.

[0031] By applying this new coating to a paper, any image with sublimation ink can be printed on the coated paper through the aforementioned processes (ink jet printer, screen printing, flexographic printing and gravure printing process) and the sublimation ink applied on the coating 1 is fixed predominantly on the surface of the coating 1.

[0032] As advantages of the invention, the following aspects should be emphasized: [0033] 1Elimination of the preshrinking step of the fabric to be printed

[0034] The unique properties of the coating make it possible, when printing on a fabric, to utilize the heat in sublimation printing to vaporize the residual moisture in the paper and coating composition within fractions of a second. As a result, the coating 1 is activated so that it softens and adapts to the fabric structure 2 (FIG. 2) and surrounds the upper side of each fabric fiber 2 that is in contact with the coating 1. Then, the coating 1 is dried by the heat, so that it is easily adhered to the fabric. This adhesion is sufficient to stably hold an image or pattern on the fabric during the time that the sublimation and fixation of the ink on the fabric fibers 2 takes place. After pressing, the coated paper easily peels off the fabric without residue and can be removed.

[0035] This unique feature simplifies the production process to just one step and eliminates the need to preshrink the fabric. This allows great savings in production time and eliminates the full cycle of preshrinking, doubling production efficiency, reducing power consumption and cutting by almost half the wear on machinery. [0036] 2Increased printed image resolution

[0037] The unique characteristic of the coating, which ensures that each fiber 2 of the fabric in its middle contact area is surrounded with the coating 1, while in contrast to commercial coatings 3, the contact with the fabric fibers 1 is only tangential (FIG. 1), provides a significant improvement in image resolution, because the coating on the fabric fibers allows the positioning of the image in relation to the fabric to be maintained, so that the sublimation ink at each image point is transmitted in the same place of the fabric during the entire process duration. [0038] 3Increase of the fixation rate of the ink on the fabric fibers

[0039] The unique characteristic of the coating, which ensures that every face of the fabric in its middle contact area is surrounded with the coating, allows the ink to remain in direct contact with the fiber during the sublimation printing process. This increases the contact surface of the ink to the fabric fibers, which can increase the fixing speed of the sublimated ink on the fabric by 20%, without the ink being lost as steam due to the higher surface area of the coating with respect to the fabric threads. This means that the fabric printed with the coated paper shows more defined edges, contours and color gradients, higher color contrasts, a higher color depth and liveliness. Therefore, this new coating can be used to achieve a significant improvement in all visual aspects. [0040] 4Increased resistance to fading of the image or pattern by ultraviolet light (UV) or washing

[0041] Due to all the characteristics that the coating provides for the printed fabric, in particular by the larger ink fixing surface for the fabric fiber, a wider adhesion on the surface of the fabric fibers, a higher color throughout the fabric, a higher contrast, a higher liveliness and intensity of the colors and a higher image resolution, the light resistance of the pattern with respect to the effect of UV light is increased by at least 20%, as well as resistance to fading during washing.

[0042] Due to the special properties of the inventive coating for a printing paper, a fabric printed with this coat can provide a quality superior to the prior technique, both in terms of the visual perception of the pattern itself, as well as durability, print quality and wear resistance by the exposure to UV light, washing and its resistance to factors such as perspiration, friction, etc.