Fabric pre-treatment with Pregen
Fabrics to be printed, whether using traditional or digital, must be carefully prepared by cleaning them of any impurities that might compromise printing. They also have to be hydrophilic, flat, straightened and stabilized in dimensions.
In addition to all these requirements, in order to be ready for digital printing, the fabric must be addictivated to:
Allow the fixation of the dye contained in the ink to the textile substrate
Optimise the intensity and brilliance of the prints
Control the spreading of the ink on the fabric, so improving the printing definition
Support the ink absorption on the fabric, so making drying easier
Support the penetration of the dye contained in the ink
In general, fabric preparation is essential for all the digital printing processes, except for pigment printing. It is optional for digital printing with pigment inks but it’s useful in order to obtain deep and brilliant shades.
It may be applied using various application systems, such as padding, all over printing or spraying. Padding is the most common method thanks to ease of use and optimum dimensional control of the fabric.
After the application of the Pregen preparation for digital printing, the fabric must be dried.
In case of preparation meant for printing on silk, wool, polyamide or other cellulose fibres, the drying temperature should not exceed 105°C and drying shall be made in such a way to have a residual humidity on the material of approx. 50% of the nominal rate of recovery.
Lower residual moisture values waste energy and may lead to thermal degradation of some preparation components and consequent loss of colour yield.
In the case of polyester fibers, there is no temperature restriction, but a too quick drying could negatively affect the printing definition.
Below table lists the main types of Pregen according to their characteristics.
The main types of PREGEN
ATRAFIX blanket adhesives
In order to assure optimum digital printing, it is necessary that the printer blanket must have the right degree of tack. The Monna Lisa printer blanket requires application of a permanent adhesive.
The ATRAFIX ML series was created specifically for this purpose. We are talking about solvent-based acrylic co-polymers that may be applied to the blanket using the supplied squeegee.
For example, the blanket may be prepared by spreading a bottom layer of ATRAFIX ML/T and applying a top layer of ATRAFIX ML/S or ATRAFIX ML/K. The first one creates a soft and high-tack film (more suitable for cellulose fibres) while the second one creates a harder and high-tack film (more suitable for silk and synthetic fibres).
The adhesives may be mixed in order to obtain an intermediate characteristic as needed by specific production requirements.
Periodical washing of the blanket is recommended using RESINA MC which allows to remove the dirt so refreshing the initial adhesiveness. Washing the blanket using only water, by turning on the rotating brushes placed in the lower side of the blanket, is not effective.
When the adhesive needs to be totally replaced, the surface layer has to be restored using additional ATRAFIX ML/S and ATRAFIX ML/K. We suggest periodically refreshing the blanket, removing the adhesive layers by using ADHESOLV (environmental friendly and not flammable solvent).
In order to obtain the desired hand-touch, all the commonly used finishing products may be applied on digital printed fabrics according to the specific fiber.
We suggest using quality products like:
softening silicon microemulsion
hydrophilic and cross-linking silicon micro-emulsion
non-yellowing concentrated cationic softener
very soft polyurethane resin
thermoplastic resin for full and hard hand effect
cross-linkable resin for full and hard hand effect
darkening silicon softener
polyethylene wax for full hand effect and improved sewability
anti-crease glyoxalic resin for full hand effect
OXAL XS / XH / R3N
FORPON SCR / TEXIPRINT B / TEXIPRINT GA
fixing agent for silk and wool
POLIFEN SB 40
fixing agent for polyamide
In addition to the traditional finishings, new “wellness” finishings are available.
They allow to apply substances onto the fabrics to enhance the interaction between the final user and the surrounding environment bringing particular benefits:
fragrance release (lavender, rose, lemon, sandal, etc)
thermoregulator at 25°C or 31°C
release of elagic acid (anti-inflammatory)
release of linoleic acid (moisturizing)
flame retardant for PES
fluorine-free water-repellent treatment