Canvas Bleached water proofing
Since we are considering heavy to very heavy fabrics for bleaching, a continuous processing may not yield expected quality results. The best suitable machineries are as below:
(1) Jumbo Jiggers, (2) Cylinder Drying Machine, (3) 3 bowl - Padding Mangle
Scouring and Bleaching in Jigger followed by cylinder drying, water proof emulsion padding and drying - are the main process route for this variety of fabric.
In general an anionic wetting/scouring agent would be employed in combination with caustic soda, hydrogen peroxide and stabilizer. The bleaching process timing and recipe are adjusted as per the requirement and would be carried out for a minimum period of 90 to 120 minutes. A thorough neutralization of alkali and washing off are essential steps for good water proofing finish.
In bleached water proof finishing, a cationic wax emulsion is employed along with necessary quantity of paraffin wax and French chalk filler powder. All these components would form a homogeneous thick padding solution. Guar gum or CMC is used as a thickening and binding agent for holding all the ingredients in a uniform suspension.
In general a pure only water proof material would not be manufactured. The customer would prefer multiple specialty finishes, such as fire-resistance, rot proofing, etc. Necessary chemicals would be included in the padding bath to impart the required qualities.
Water Proofing Recipe:
I padding Recipe:
Waxol PA (ICI) = 100 gpl
Paraffin wax = 20 gpl
CMC (Cellpro MVB) = 10 gpl
An emulsion is made using all the aove chemicals at a temperature of say 80°C and applied on the fabric through a 2 dip 2 nip padding mangle at 70% expression. The padded fabric is dried either in cylinder or hotflue at a temperature of 100 to 110°C. Then the dried fabric is again padded with a solution of Aluminium Formate 75 gpl in a 2 dip 2 nip padding mangle and washed throghly in washers or jiggers.