Pressure Sensitive Adhesive

Defined as a product that bonds two surfaces when pressure is applied to bond those surfaces together.
The adhesive is normally tacky at room temperature.  Plastic tape for sealing boxes is a good example of a pressure sensitive adhesive.  Apply the tape and press the adhesive side down onto a surface and you have an immediate bond.

For the purposes of this discussion we will present a pressure sensitive adhesive (psa) as a water based or hot melt adhesive.

1. Water Based
   Normally an acrylic product with water making up 35% or more of the adhesive by weight, the water based psa will be tacky when wet but it will also remain tacky when the water has evaporated.  Gluefast offers water based psa’s with varying strengths and tack.  Our GF 779 has long been used to label untreated polyethylene & polypropylene.
   1. The water in the adhesive will penetrate the surface pulling the acrylic with it, drying as it is absorbed and leaving the dried acrylic film behind.  The psa remaining on the surface will air dry.
   2. If the surface is impervious to water, such as a plastic film, the only way to for the water to evaporate is by air drying.  Therefore, if the same amount of adhesive is applied separately onto paper as one substrate and plastic film as the other and allowed to dry, given the same humidity, temperature and air flow it will take much longer for the adhesive to dry on the plastic film.
      
      
2. Hot Melt Adhesive
   A hot melt psa is more complex and is rubber based.  Hot melt adhesives are 100% solid and thermoplastic, being liquid at elevated temperatures and solid at ambient room temperature.  Typical application temperatures are 275-325 degrees F.  By adding mineral oil or other items to reduce the tack, you can alter the adhesive strength.
   While non-psa adhesives are available in glue stick form, psa’s are generally limited to bulk applicators.
   1. High volume users will apply the hot melt onto a substrate using automatic applicators.  One example for this use is the beverage industry which uses low tack psa for palletizing of beverage cases, reducing the need for stretch wrap.
   2. Lower volume users may opt for Glue Dots®­, small dots or lines of hot melt psa applied onto a silicone release liner.  You may see this on some of the many mailings you get with a plastic membership card applied onto a paper carrier.  If the adhesive dots are perfectly round the product is likely to be a Glue Dot.

Gluefast offers both water-based adhesives and hot melt adhesives, including a full line of Glue Dots®.  If we don’t exactly have the adhesive you need we may be able to formulate a product just for your needs.  We are currently working on a project where a glass bottle will be in placed into a thermoformed tray.   The end user does not want the bottle to rotate in the packaging, and wants to avoid the use of hot melt or Glue Dots®.  We have custom formulated a water based psa that will work well without transferring the adhesive onto the bottle.

Have a special glue project?  Let Gluefast help provide a solution!