FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to a heat press or calender for use with a textile printer which uses dye sublimation.

Digital printing has replaced traditional methods in different branches of the graphics industry. There are multiple reasons for this shift but the main drivers are the cost-efficiency, possibility to personalise prints and flexibility.

The textile printing business is part of the graphics industry and the same trends apply. Traditional screen-printing is being replaced by digital textile printing solutions using ink jet and sublimation printing for shorter production runs and prints that require multiple colours and photographic imagery. The digital alternatives are ideal for the personalisation of prints, which is extremely popular nowadays.

Sublimation printing is a technique that uses heat sensitive inks. These inks turn into gas under the influence of heat and combine with various textile media such as a 100% polyester medium. The ink may actually become part of the structure of the material so that the images on the fabric do not fade or crack even after multiple washing. The ink may be transferred to the textile using transfer paper or a blanket. US 20080229962 A1 to Shedd et al relates to an example of sublimation transfer paper.

Calendering is used as a finishing process on textiles, typically to smooth, coat or thin a material, and to cause sublimation to occur when sublimation inks are in use. The fabric is passed through rollers, or between rollers and a drum, at high temperature and pressure with the inks being applied. The elevated temperature causes rapid sublimation, leading to a cloud of ink vapor. The vapor can get back to the textile, blurring the image or can cause breathing problems for the operator.

The excess ink, that wasn't absorbed by the fabric, needs to be absorbed to avoid smudging the image. The textile is thus placed on a moving belt and paper (“protective/kraft paper”) is generally placed between the textile and the belt to absorb the ink. The paper mops up excess ink and is disposed of, and new paper is used for the next cycle. Thus the next cycle begins with a clean system. If the excess ink is somehow still present during the continuation, then ghosting of the new image may occur so it is important to do each image with fresh paper. In one implementation, in which a mirror image of the print to be made on the fabric is provided on transfer paper. The transfer paper is placed on the fabric and moved to the heat press or calender to carry out the sublimation process to transfer the image from the paper to the fabric. In such a case the transfer side of the fabric is in any event protected from the dye to be disposed on the calender as a new transfer is used. Hence there is no issue of ghosting on the new image or part of the fabric. The other side of the fabric, away from the transfer paper, however, does need to be protected from the effects of absorbed ink and this is achieved using another protective paper in order to prevent dye that penetrates the fabric from getting onto and contaminating the calender.

A second implementation, direct printing—in which the ink is printed directly onto the fabric requires protecting of the calender from both sides of the fabric with protective paper.

A belt calender is disclosed in U.S. Pat. No. 7,000,536 to Markus Laitila et al, filed May 3, 2001.

Thus in the current art, protective paper, or tissue paper, is used for excess dye absorption in a calender or heat press to protect the drum/platen and/or the blanket from the excess ink, and to protect the image from smudging. The paper, typically positioned between the fabric and the drum, absorbs excess dye that does not penetrate into the fabric.

The protective paper is a consumable and a waste product of the sublimation calender or heat press process. Suitable protective paper is often provided by the manufacturer of the calender.

The constant need to replace paper is wasteful. The paper does not do anything to control the cloud of particles due to sublimation.

SUMMARY OF THE INVENTION

The present embodiments may provide for an endless feed belt that can be cleaned directly, or for a drum that is cleaned directly. Hence the protective paper is not needed.

In the present embodiments the drum or platen may be protected by a moving belt, typically the feed belt, or there may be a feed belt and a pressure belt. The feed belt is an endless belt, and any of the belt, or both belts, or the belt and drum, may be cleaned as they turn. The feed belt, and for that matter the pressure belt, may perform the function of absorbing excess dye from the fabric and may be cleaned before being involved in forming the next image

According to an aspect of some embodiments of the present invention there is provided a calender for fixation/transfer of dye sublimation, comprising:

a textile inlet;

a textile outlet;

a heat press or heated drum;

an endless belt for driving the textile from the textile inlet to the textile outlet through the heat press, the heat press being held at a temperature sufficient to cause sublimation of the at least one dye; and

a cleaning station for cleaning the endless belt, the cleaning station being located downstream of the textile outlet and upstream of the textile outlet.

In an embodiment, the textile is in physical contact with the belt and the cleaning station is configured to clean dye residue from the belt.

In an embodiment, the cleaning station comprises a squeegee that cleans by wiping over a surface of the belt.

In an embodiment, the cleaning station comprises an applicator for applying a cleaning fluid to the belt.

In an embodiment, the belt comprises a smooth non-absorbing surface.

In an embodiment, the belt comprises an absorbing material.

An embodiment may comprise a heating unit at the cleaning station to cause sublimation of ink residue on the endless belt to aid with cleaning.

An embodiment may comprise a drum, a drum cleaning station for cleaning a surface of the drum, the cleaning unit being located downstream of the outlet point and upstream of the inlet point.

An embodiment may comprise a linear platen having a length, the platen being independently heatable at different locations to form a temperature profile along the length.

An embodiment may comprise a second endless belt and a second endless belt cleaning station, the second endless belt cleaning station being located downstream of the outlet point and upstream of the inlet point.

According to a second aspect of the present invention there is provided a calender for fixation/transfer of dye sublimation, comprising:

a textile inlet;

a textile outlet;

a heat press;

an endless belt for driving textile from the textile inlet to the textile outlet through the ink applicator and the heat press, the heat press configured to apply pressure to textile on the belt, the heat press further being heated to a temperature sufficient to cause sublimation of the dye,

a vacuum source to clear vapor resulting from the dye sublimation.

In an embodiment, the textile is in contact with the belt during application of the at least one dye and a cleaning station is located downstream of the textile inlet and upstream of the textile outlet to clean dye residue from the belt.

According to a third aspect of the present invention there is provided a method of using a calender and dye sublimation, comprising:

inserting a textile into contact with an endless belt;

using the belt to drive the textile against a heat press;

maintaining the heat press at a temperature sufficient to induce sublimation of at least one temperature sensitive dye on the textile;

removing the textile; and

cleaning the endless belt.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

