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GENERAL COMPOSITION OF PRINT PASTE

GENERAL COMPOSITION OF PRINT PASTE. DYESTUFF WATER THICKENER HYDROTROPIC AGENTS SUCH AS SOLVENTS(Diethylene glycol) HUMECTANT (Urea) MILD OXIDIZING AENT DEFOAMING AGENT. DYESTUFF, THICKENER. DYE CLASS DEPENDS ON THE CLASS OF FIBRE TO BE PRINTED THICKENER

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GENERAL COMPOSITION OF PRINT PASTE

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  1. GENERAL COMPOSITION OF PRINT PASTE • DYESTUFF • WATER • THICKENER • HYDROTROPIC AGENTS SUCH AS • SOLVENTS(Diethylene glycol) • HUMECTANT (Urea) • MILD OXIDIZING AENT • DEFOAMING AGENT

  2. DYESTUFF, THICKENER • DYE CLASS DEPENDS ON THE CLASS OF FIBRE TO BE PRINTED • THICKENER HIGH MOL. Wt. NATURAL (STARCH), MODIFIED NATURAL (CMC, GUAR GUM), SYNTHETIC (POLYACRYLATES) POLYMERS WHICH WHEN DISSOLVED OR SWOLLEN IN WATER GIVE HIGHLY VISCOUS SOLUTION OR GEL

  3. ESSENTIAL QUALITIES OF THICKENER • COMPATIBILITY WITH OTHER INGREDIENTS OF PRINT PASTE • PRINT PASTE ON PRINTING SHOULD SINK ON FABRIC AS QUICKLY AS POSSIBLE. THIS IS DESIRABLE FOR WET-ON-WET PRINTING • FREE FROM INSOLUBLE IMPURITIED TO AVOID SCREEN CHOCKING AND UNEVEN OUTLINE PRINITNG • MUST HAVE SATISFACTORY ADHESION TO FABRIC AFTER PRINTING AND DRYING. THE THICKENER FILM SHOULD NOT BE BRITTLE SO AS TO FLAKE OFF FROM THE FABRIC SURFACE • THE THICKENER PASTE SHOULD BE SHEAR THINNING AND THIXOTROPIC • NO AFFINITY TOWARDS DYE AND OTHER CHEMICALS IN PRINT PASTE • DURING FIXATION THE THICKENER FILM SHOULD EASILY LEAVE THE DYE AND ALLOW ITS PENETRATION INTO FIBRE • SHOULD BE EASILY REMOVED FROM THE FABRIC DURING WASHING

  4. HYDROTROPIC AGENTS • WATER SOLUBLE COMPOUNDS • IINCREASE WATER SOLUBILITY OF OTHER COMPOUNDS • UREA, DIETHYLENE GLYCOL, GLYCERINE ETC. • MULTIPLE FUNCTION • HYGROSCOPIC AGENTS • DYE DISSSOLVING ASSISTANTS SOLVENTS • IMPROVE DYE SOLUBILITY • PREVENT DYE AGGREGATION IN PRINT PASTE • FACILITATE DYE DIFFUSION • IMPROVE COLOUR YIELD • Deg, THIODIETHYLENE GLYCOL.

  5. HYGROSCOPIC AGENTS • FACILITATE STEAM CONDENSATION AT PRINTED PORTION DURING STEAM FIXATION • ESSENTIAL FOR DYE FIXATION • IF MORE THAN OPTIMUM, LOSS IN PRINT SHARPNESS DUE TO EXCESSIVE STEAM CONDENSATION

  6. pH CONTROLLING AGENTS • PROVIDE ACID OR ALKALINE pH for dye FIXATION • ACID pH ; NON-VOLATILE ORGANIC ACIDS CITRIC, TARTARIC ACID OR ACID LIBERATING AGENT (NH4)2SO4 • ALKALINE pH Na2CO3 OR NaHCO3

  7. REDUCTION PROTECTION • CERTAIN DYES PARTICULARLY THOSE CONTAINING AZO GROUP ARE SUSCEPTIBLE TO REDUCING INFLUENCE OF THICKENER AND OR FIBRE (CELLULOSE) DURING STEAMING • 5-10 g?kg NaClO3 IN CASE OF SYNTHETIC FIBRE PRINTING • 10 g/kg m-NITROBENZENE SULPHONIC ACID FOR REACTIVE DYES ON COTTON

  8. DEFOAMING AGNET • FOAM GENERATION • DURING HIGH SPEED PRINTING (ROTARY) • IN PRESENCE OF DYES AND CHEMICALS HAVING SURFACE ACTIVITY • SPECKY PRINTS • SILICONE DEFOAMER

  9. MECHANISM OF DYE FIXATION • STEAMING, MOST COMMON METHOD FOR DYE FIXATION SEQUENCE PRINT > DRY > STEAM > WASH > SOAP > WASH PRINT STAGE • DYE, OTHER CHEMICALS AND THICKENER IN SOLUTION FORM ON FABRIC DRYING STAGE • WATER EVAPORATION • DRY THICKENER FILM (CONTINUOUS) • INSOLUBLE DYE AND OTHER CHEMICALS EMBEDED IN DRY THICKENER FILM STEAMING STAGE • HIGHER WATER CONDENSATION AT THE PRINTIED PORTION • SWELLING OF THICKENER FILM • BREAKING OF FILM CONTINUITY

  10. DISSOLUTION OF DYES AND CHEMCALS IN SWOLLEN FILM • FIBRE SWELLING, DISSOLUTION OF DYE AND OTHER CHEMICALS. • FORMATION OF HIGH DYE CONCENTRATION WITHIN THICKENER FILM • DIFFUSION OF DYE AND OTHER CHEMCALS IN FIBRE • DYE-FIBRE INTERACTION • RETENTION OF DYE INTO FIBRE (DYE FIXATION) • WASHING OFF UNFIXED DYE, OTHER CHEMICALS AND THICKENER

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