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. . .. . . SAKATA INXSAKATA INX Visual Communication Technology

LEARNING & SHARING Sept.’ 2014Topic:

Types of Gravure Inks, its properties & Application

Presenter : Harshad Patel


PRINTING INKS

Printing Inks are Colored Liquids or Paste are formulated to transfer and reproduce an image from a Printing Surface to substrate

They are mainly used to give decorative effect to the substrate.

Inks are formulated by using different ingredients like Pigments , Resin , Solvents & additive to meet the requirement of various substrate, machine, & end Application.


TYPES OF PRINTING INKS

Printing Inks can be classified into following categories depending upon the Printing process.

Lithographic and Letterpress Inks.

Gravure and Flexo Inks.

Screen Inks.


BASIC INGREDIENTS OF GRAVURE INKS

Gravure ink consist of Four basic Ingredients :

Colorants / Pigments / Dyes – To provide colour to ink.

Varnish / Resin - To disperse the pigment and provide the adhesion to substrate.

Solvents -- To be used for thinning purpose & to control the viscosity of ink.

Additives -- Used for special properties.



COLORANTSColorants in Printing inks include pigments and dyes. Pigments are colour particles which are not dissolve in the vehicle & solvents, while Dyes are dissolve in the vehicle & solvents.

Pigments are mechanically dispersed in a vehicle to provide colour strength.

Various properties like Light fastness , Alkali & soap resistance, Opacity , Transparency depends upon the Pigments.



COLORANTSThe physical and chemical nature of a pigment, the size and even the shape of its particle affect the appearance of colour.

The amount of pigment and the type of vehicle used can affect hue.

The choice of pigment and the degree to which they are dispersed through the vehicle are the most important factors in determining the transparency or opacity of a printing ink.



VEHICLE / VARNISH Varnish or Binder is a prepared by dissolving resin in the solvent. The binder is a “ Glue “ that holds the ink on the substrate.

Binder can be single resin or a complex combination of resin , Plasticizers, Solvent, and Additives.

Varnishes are used for Pigment dispersion , Adhesion on the substrate & for getting the end use properties.



SOLVENTS Solvents are liquids capable of dissolving another substance without undergoing a change in chemical state or physical properties.

Solvents are used for controlling the viscosity and drying rate od liquid ink.

Solvents serves a dual function : It dissolve the resin, and it evaporates from the printed surface leaving a continuous dry ink film.



ADDITIVES Additives are used in a small quantity ( 0.2 to 3 % ) to achieve a special properties.

Typical Additives are :

•Slip Additive

•Wetting / Dispersing Agents

•Optical Brightener

•Anti-foaming Agent

•Anti-blocking Agent, Anti-static Agent

•Hardner


TYPES OF GRAVURE INKS

There are four types of Gravure Printing Inks

Reverse Printing Inks

Surface Printing Inks

Common ink for both Surface & Reverse Printing.

Printing Inks for special Application


REVERSE PRINTING INKS

Reverse printing ink are applied on flexible transparent substrate like Polyester , BOPP , Nylon , PVC , PVDC coated film etc....

In Reverse printing, Ink is sandwiched between Printing & Laminating film.

Reverse printing inks are used in Food packaging such as Biscuits,Snacks,Butter,Wheat flour Pan Masala, Mouth freshener Detergent Powder,Soap,Shampoo Coffee & Tea Pouch


REVERSE PRINTING INKS

Gravure Reverse Printing inks are formulated mainly in following system.

NC-Acrylic based inks

Vinyl based inks

Polyurethane based inks


POLYURETHANE BASED INKS

PU based inks are applicable on Polyester , BOPP , Nylon , Cellophane & PVDC coated films.

PU based inks are suitable for solvent base / solvent less / PP extrusion Lamination.

PU based inks can be further classified in to three categories depending upon the solvent system used.

Toluene & MEK Based inks

Toluene Free Inks

Toluene & MEK Free Inks


PROPERTIES POLYURETHANE BASED INKS

PU Inks has Excellent Printability and Resolubility.

PU Inks has very good Adhesion on most of the substrate.

They are High speed Printing Inks.

PU Inks has very good Lamination Bond strength and extremely

low Solvent Retention.

Suitable for Boil and Retort Application.


VINYL BASED INKS

Vinyl based Inks are used on Polyester film only, but it can also be used on BOPP substrate after adding BOPP additive.

Vinyl Inks have very good Printability and Resolubility.

Vinyl Inks have very low Solvent Retention.

Vinyl Inks have lower Bond Strength compare to the PU Inks.


NC-ACRYLIC BASED INKS

These Inks are specially used for the printing of Shrinkable PVC and Shrinkable PET.

These Inks are used for printing of Labels for beer , Fruit juices, Mineral water , Detergents & Shampoos etc…

These Inks have excellent Shrinkable Properties.

These are Non – Laminating inks


INKS FOR PP EXTRUSION

These Inks are used for the Printing on BOPP followed by PP Extrusion with PP Woven Fabric.

These Inks are used for printing of Rice , Wheat and pats food bags where higher strength is required in the laminate structure.

These Inks normally used with white backing to have good bond strength. But now inks are also available which can give good bong strength even without white backing.


SURFACE PRINTING INK

Surface printing inks are applied on Natural poly ,White poly, Pearlised BOPP , Met Polyester , Met BOPP , Foils , Paper and Boards etc...

Surface printing inks are applied on top surface , so inks should have good Gloss , Rub & Scratch Resistance properties.

Surface printing inks are used in packaging of Milk , Butter , Oil , Ghee , Cold drinks & Detergent powder etc...


SURFACE PRINTING INK

Most commonly used Surface printing inks are

General purpose surface ink

Heat Resistance surface ink

Deep freeze surface ink

Oil & Fat Resistance ink

Two pack inks

Heat Resistance Foil & paper inks


GENERAL PURPOSE SURFACE INK

These are Polyamide based ink and used for the printing of treated PE, CPP, and BOPP or Met Polyester where Heat Resistance is not required.

These inks are mainly used for the printing of Carry Bags, Toffee and Gift wrappers. It has very good Gloss and adhesion to most of the treated films.


HEAT RESISTANCE / DEEPFREEZE INK

These are NC - Polyamide based ink having good Heat resistance properties.

These inks are mainly used for the printing of treated PP, BOPP, CPP, LDPE & Heat sealable BOPP etc...

These inks are used for Water, Milk packaging and cold drink bottle wrapper .It has a very good deepfreeze resistance.


OIL AND FAT RESISTANCE INK

These ink are used for Oil packaging. Normally a two pack OPV is required where higher oil & fat resistance is needed.

These inks are used for the printing of treated natural and opaque PE.

There are also common inks available for both water/milk and oil / fat packaging.


TWO PACK INK

Two pack inks are used for packaging of detergent and animal fat where higher chemical resistance is required.

In two pack inks hardner is added at the time of printing. Normally shelf life of two pack ink is 8 – 12 hrs after adding hardner.

HR INKS FOR FOIL AND PAPER PRINTING These inks are NC based inks

and used for the printing of Pharma foil and paper where higher Heat resistance and minimum solvent retention is desired.


COMMON INKS FOR BOTH SURFACE & REVERSE PRINTING

There are also common inks available which can be used for both reverse and surface printing.

These inks are Toluene and MEK free.

These are NC-PU based and for reverse printing. It is used directly for surface printing with addition with slip additive.

These ink can be used for the printing of corona treated pet & BOPP

It has very good Bond strength when used in Lamination and has very good Heat , Scuff and Crinkle resistance when used for Surface printing.


PRINTING INKS FOR SPECIAL APPLICATION

Tattoo Inks : For making Tattoo a release lacquer is applied on untreated BOPP followed by Vinyl or NC based Inks.

It is further laminated with release paper by applying water based or pressure sensitive adhesive.

Heat Transfer Inks :These inks are printed on Pet and then transferred on the Cable or PVC Pipes by applying Heat and Pressure.