Acrylic Printing

Printing of Acrylic by Direct Style

Principle

           

Acrylic fabric can be printed with cationic dye as per the dyeing procedure.

ð  Printing of Acrylic is differs from dyeing as below:-

·         Dyes of various (Cationic/Basic) classes can be used in combination with each other.

·         No blocking effect occurs.

·         Colour build up is better.

Ingredients

(1)   Dyes:-

·         Cationic, disperse and vat dyes are suitable for printing acrylic fibres.

·         Cationic dyes are the most important and most widely used class of dyes for printing of acrylic fabric.

·         Prints produced with cationic dyes have excellent wet and rubbing fastness.

·         Disperse dyes give dull shades when printed on acrylic fabric.

·         Sharp outline with black colour is produced using disperse dyes only.

(2)   Thickeners:-

·         Thickeners having high solid content are best suitable for this printing.

·         Modified gaur gum, tragacanth, British gum etc. are suitable thickeners for printing of acrylic

·         Since the fabric is hydrophobic in nature thickener selection is important factor.

·         Modified guar gum is alkaline in nature and hence has to be neutralised with acid.

·         British gum – gum tragcanth mixtures perform well.

(3)   Swelling agent:-

·         To increase the diffusion of dyes in the fibre and colour value, fibre swelling agents are added in the paste.

·         Excessive use of swelling agents may result in increased bleeding of dyes.

·         Eg. Resorcinol, Phenol

(4)   Wetting agent or Solvent:-

·         Thiodiethylene glycol is a solvent for the cationic dyes, some of which may be sparingly soluble in water, especially at low temperature.

·         Addition of swelling and oxidising agent decreases the solubility of the dye, hence addition of solvent is desirable.

(5)   Acid:-

·         Paste contains acetic acid as well as tartaric acid to improve the solubility of the dyes and to adjust the pH of paste.

·         Since acetic acid is lost by evaporation during drying of the prints, non-volatile acid (tartaric acid) supplies the necessary acidity during steaming.

(6)   Oxidising agent:-

·         Sodium chlorate is used to protect the brightness of the dye against any possible reduction of the dye under the prolonged steaming conditions.

Procedure

·         The printing paste is prepared as follows:-

      50  parts    Cationic (Basic) dye

                              20 parts     Acetic acid (50 %)

                      20 – 30 parts     Thidiethylene glycol

                      20 – 30 parts     Tartaric acid

                            165 parts    Water

                                5  parts    Sodium chlorate

                            680  parts    Thickener

                              20 parts    Resorcinol/Phenol

                          1000  parts

·         After printing, fabric is dried and steamed in star ager at 103ºC for 40 minutes.

·         A temperature of 105ºC is the maximum allowable steaming temperature.

·         If it exceeds 105ºC undesirable effects like alteration of hand, bleeding, increased fabric shrinkage etc. result.

·         The steamed fabric is after treated with a bath containing 1 to 2 gpl anionic detergent at 60ºC for 30 minutes.

·         Finally, the cloth is rinsed, washed and dried.