Hot Melt Pressure Sensitive Adhesive backed fastening tape is used heavily in assembly applications worldwide for automotive, packaging, aerospace and other applications. This adhesive is applied to the smooth surface back of the fastening tape then a removable release liner is laminated to the adhesive and the product wound on a reel or die cut to the size and length required.
The major concerns regarding the coating of fastening tape with hot melt adhesive prior to production are as follow:
1. Poor adhesion (lamination) between adhesive and release paper can occur for the following reasons:
- Coating environment is too cold. For a high Tg HMPSA, adhesive loses its surface tack immediately after it is coated in a very cold working environment. This happens sometimes in the winter time. To avoid this problem, consistent room temperatures are required in the coating room.
- Those components of a less compatible SBC-tackifier blend tend to phase out and lose surface tack particularly in a low temperature working environment due to a super cooling process. The surface of adhesive is shinny exhibiting light blue color when this phenomenon appears.
- The release agent on release paper migrates to adhesive surface.
- The tension control of coated tape and release liner is not synchronized during lamination.
2. Poor Die-cutting.
- Adhesive is too tacky and tends to stick on the edge of cutting die.
- The release force of used release paper is too low to cause a separation of adhesive and release paper during die-cutting.
It is recommended that a thorough evaluation of the substrates, the coating system and environment, the adhesive and the release liner are made prior to production of hot melt pressure sensitive backed Velcro style , Hook and Loop fastening tape.