How to Formulate Water Based Folding Carton Inks

Folding cartons are used to pack a wide range of end products, from soft drink beverages to cigarettes and tobacco. They are typically printed by gravure andflexography and utilize multiple colors and overprint varnishes.

Inks for folding cartons need to be formulated with moderately high gloss and good surface rub resistance. Specific modifications to these ink formulations include:
 

• The modification to C.O.F. (slip) values,
• Product resistance (water, alcohol, detergent etc.), and
• Heat resistance

In general, increase in wax levels increases rub resistance and slip values (lowers C.O.F.). Waxes can also have an impact on other surface properties like water and soap resistance. 


 

Common Types of Folding Carton Material

Typical substrates for folding cartons include paperboard and small flute corrugate Solid Bleached Sulfate (SBS). Main types include:
 

• SBS is a bleached paperboard made from mostly virgin bleached wood pulp
• SBS Kaolin Coated Kaolin/2-sided Kaolin is a clay coated board
• CUK (CNK/SUS) chemically bleached with a Kraft back
• Polyethylene (PE) resin coated SBS board
• Uncoated Recycled Paperboard made from 100% recycled paper
• Coated Recycled Paperboard made from 100% recycled paper with a kaolin clay coating

Tobacco Packaging

Packaging for cigarettes and tobacco require strict monitoring of the resins and additives that go into the ink formulations, particularly because raw materials can leave residual odors which can penetrate through the packaging and into the product. With this in mind it is possible to select key raw materials which are formulated with low residual odor and "cleaner" content.

Now, let's see what are the main type of raw materials used to formulate inks for folding cartons & various factors which should be considered while selecting them.

 

These are the backbone of the formulation and are used for establishing the key properties of adhesion, heat resistance and gloss. 
 

• The industry standards are acrylics and styrene acrylic emulsions, which offer a range of properties based on the targeted applications
• Polyurethanes tend to be more expensive and have limited compatibility with acrylic resins

» Find All Suitable Resin Grades for Inks  

 

Formulations - Folding Carton Gravure Ink

Applicable segments: Beverage cartons, Cigarette cartons, food packaging 

 

Selecting Waxes for Water Based Folding Carton Inks

The main purpose for including waxes in these formulations is to improve rub resistance. The table below will familiarize you with the different performance characteristics of waxes used with water based folding carton inks.

 

Generally the larger the particle size - the greater the rub resistance, but also the greater the effect on gloss, so in general you want to formulate with the smallest particle size that gives an acceptable level of rub resistance. Paraffin waxes are used almost exclusively for imparting water resistance and shouldn't be used unless this is a requirement.


 

Selection Defoamers for Water Based Folding Carton Inks

Defoamers can be categorized into silicone based defoamers and non-silicone based defoamers (e.g. mineral oil based defoamers). In general, silicone based defoamers are the most effective for eliminating foam, but they are generally restricted to being used in the pigment grinding stages of ink manufacture because they require a lot of sheer to ensure that they are fully dispersed within the ink system. 

 

Select Pigments for Water Based Folding Carton Inks

Select Surfactants for Water Based Folding Carton Inks

Surfactants are used to improve substrate wetting and for pigment wetting during the pigment grinding stage. The type of chemistry to use is often dictated by local availability and price. One should also consider that the more surfactant you use, the more the ink tends to form foam. Many surfactants have the effect of stabilizing foam, so it's important to select the right surfactant for your system.