Fabric Pretreatment: Unstable fabrics such as knits and light weight woven fabrics frequently need to be supported by a suitable stiffening binder, or temporary lamination to a support paper. One of the fabric precoat machine is shown in the fig, below.
Fabric Precoat Machine consists of :
FABRIC FEEDER
· Fabric unwinding device with fabric tension roller for fabric rolls of 250mm
· Fabric join bar with needle holder
COATING
Stainless steel coating unit
· This unit could handle all textiles of width up 1600mm.
· The speeds of coating/spraying and speed of fabric are adjustable according to used textile.
· All set-ups could be stored into internal memory and later called out for repeated procedure.
· Separate liquid tank including air mixer allow easy exchange of used coating formula.
DRYER
· The dryer is infrared; double walled and is fully insulated to minimize any heat loss.
· The heating and regulation are controlled via a digital temperature controller situated on the electrical cabinet
· Small exhaust fan is situated on top of dryer.
BATCHING
· Fabric re-winder can accommodate rolls up to 250 mm diameter and includes automatic speed control, which is regulated by a "dancing" bar.
· The unit consists of scroll roller and one side textile edge control.
All functions of the Precoat-X are controlled by PLC with programmable terminal in auto and manual mode. The control panel is located in easy to reach position.
All units are mounted on swivel wheels.
OPTIONAL FEATURES
Set of recommended spare parts
On-site installation and training
Fabric are pretreated with various surface active agents, gums and fine particulate coatings inorder to maximise the absorbency and reactivity of the textile substrate towards the inks, while minimizing their spreading to prevent loss of defintion and coor intensity. Many patented and propreitory formulations exists, ranging from simple formulations of soda ash, alginate and urea to more sophisticated combinations of cationic agents, softeners, polymers and inorganic particulates such as fumed silica. Many of these have been aimed at fashion fabrics such as cotton, silk, nylon and wool. 3PInkjet Textiles (Germany) is marketing pretreated fabrics ready for inkjet printing.
A partial alternative to pretreatment of fabrics is the development of inkjet head technologies capable of using much higher viscosity inks. However, the ongoing need for some special preparation and pretreatment of fabrics is probably unavaoidable. Eventually, this may become as widely accepted if it results in significantly improved color yield and reduced consumption of expensive inkjet inks. Novel preparative methods such as plasma treatment may also have much to offer in terms of primary adhesion and dyestuff fastness.
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