Strytech Group Inc. - Blog

Box Manufacturing: Choosing the Right Adhesive

Posted by Howard Neal on Dec 17, 2010 9:01:00 PM

corrugated boxes

Increasingly, paper mills are using more recycled paper in their paper making operation. This introduces contaminates such as coatings, adhesives, and inks that make bonding and water absorption more difficult for the paper rolls produced. 

 These paper rolls used in corrugated box manufacturing make the gluing process more difficult due to shorter paper fibers, the desire for greater board strength, and the need for a print surface that enhances print quality.  Based on these factors, the most common type of adhesive used in the box making operation today is a resin emulsion.

Resin emulsions or "white glues" are petroleum-based products that replaced dextrins in most glue lap operations because of the factors above and a faster speed of set.  Although resin emulsions are slower setting than hot melt adhesives, the polymer advances in technology have allowed a greater range of bonding at a lower cost per pound. In addition equipment cost is lower and maintenance is less troublesome and less costly than hot melt.

The most common resin emulsions used on kraft paperboard, chipboard, and mottel white surfaces are based on poly vinyl acetate polymers.  The poly vinyl acetate based adhesives exhibit good machining and easy cleanup.  These adhesives can range in viscosity (thickness) from thin for spray applications, heavier for extrusion, and heavier yet for roller or wheel applications

They can also be adjusted in solids level to provide a very quick speed of set in a straight line operation or slightly slower set speed for a right angle, shingle stack compression, or hand applications.  Specialty chemicals can be added for greater wet tack or enhanced penetration into tight board.

When special formulations are needed to bond more difficult surfaces, Adhesives formulated from vinyl acetate ethylene co-polymers are typically utilized. These adhesives bond well yet are more difficult to clean because they are more water resistant.

Once a bond is formed with a resin emulsion, it is stable over a very wide temperature range, going from sub-freezing to the destruction point of the paper.  This is another reason for their use over hot melt.

In order to make an excellent bond that yields full fiber tear, testing of an adhesive on the corrugated box in a test environment is recommended.  This is accomplished by applying a small amount of adhesive to one surface and compressing the two surfaces together for 30 to 60 seconds.  If a bond can be formed the starting point is confirmed for the resin emulsion adhesive needed.  Then it is a matter of determining the set speed and viscosity required for that particular operation.

The basic premise for the formation of a fiber tearing bond is the liquid adhesive comes in contact with both surfaces and is held together as the water is absorbed leaving the solids portion of the adhesive.  It should be noted, if the bond is made, then broken even though the adhesive has yet to dry, the bond is lost and typically cannot be regained.

The adhesive speed of set is controlled not only by its formulation, but also by the amount of adhesive applied and the compression setting.  The amount of pressure needed to make a proper bond is critical.  The two surfaces have to be snug, but not to the point that liquid adhesive is squeezed out of the glue joint.

The plant environment, its ambient temperature and humidity, will affect the paperboard, and in turn the absorption of the water into the paper, which will impact the speed of set of the adhesive.  The higher the solids portion of the adhesive means less water to absorb, resulting in a quicker speed of set.

If your plant is located in the states of Illinois, Michigan, Iowa, Minnesota, or Wisconsin, we would welcome the opportunity to analyze your operation and show the most cost effective selection of adhesive based on substrates, machinery, and environment.

We can be reached at 847-509-7566.

Tags: adhesion, box plants

Industrial Adhesive Basics

Posted by Howard Neal on Dec 2, 2010 5:37:00 PM


In meetings with plant and maintenance personnel, I am often asked about the different types of adhesives.  Here is an overview on industrial adhesives that could be helpful to those of you who may have questions regarding adhesives.


Dextrin adhesives are starch-based products, usually derived from industrial grade corn starch.  They are economical in price, and do well in bonding paper stock.  These adhesives typically machine cleanly, and are easy to clean up, normally with warm water.

The major drawback for their use in most packaging sealing operations is their slow set speed.  Generally over twenty seconds compression time is needed to form a good bond, which is not suited for high speed operations.

These adhesives are used typically used in paper converting operations, with point-of-purchase production being a common use.  We have a unique line of products for this purpose.


These adhesives, commonly called "white glues" are petroleum-based products that replaced dextrins where increased speeds in case and carton sealing operations were required. The most common resin emulsions are based on polyvinyl acetate polymers, which exhibit clean machining and clean up with warm water since they are water soluble.  They are commonly used for the glue joint in corrugated box production.

When special formulations are needed to bond less porous surfaces such as SBS/SUS carton stock or corrugated boxes with coatings, Vinyl Acetate Ethylene(VAE) polymers are used.  The result is an adhesive that bonds well, but is more difficult to clean.  Hot water is needed to clean these products off the equipment as these polymers are water resistant.

For non-porous surfaces, VAE polymers with certain adhesion promoters or Acrylic-based polymers are utilized to bond these surfaces.  

With any of the resin emulsions, once the bond is formed, these products are stable over a very wide temperature range.


HOT MELTShot melt adhesive

Hot melts are also petroleum-based products that are 100% solid at room temperature and become liquid when placed in hot melt applicators at raised temperatures for application to the substrate.  Depending on the product and use, the application temperature can range from 225-425 degrees F.

For a high speed packaging operation, hot melts are used for carton seal or case seal due to a speed of set of as little as 1-2 seconds to form a bond. There are hot melts specifically designed to be used for these applications where the packaged product will be a freezer-grade application.

The base polymer of hot melts can be Ethylene Vinyl Acetate(EVA), polyethylene, or metallocene, with the majority of products being EVA-based when it comes to packaging or paper converting applications.

A fourth polymer type, Polyamide-based hot melts, are used where special needs arise, such as very high temperature applications or high strength needs.  Polyamide hot melts also show better resistance to oils and solvents.

One other category is APAO-based polymer hot melts, which are used where long open time and good tack are needed.  A typical application for these hot melts would be in mattress production.

Pressure Sensitive Hot Melts

A special class of hot melts are the ones that remain tacky even after they are cooled to room temperature.  These hot melts are compounded from synthetic rubber-based polymers and can be strong with a permanent bond, or removable such as those used for name tags.

If your facility is in the states of Illnois, Michigan, Wisconsin, Minnesota, or Iowa, we would welcome the opportunity to discuss ways to optimize your adhesive usage or hold a seminar on Industrial Adhesives 101 for designated plant personnel.


Tags: packaging operation, 100% solid, industrial adhesive