Fastening tape (Velcro / Hook and Loop) is widely used in products we all use on a daily basis such as clothing, shoes, house wares, furniture, stationary, vehicles, construction, etc. While fastening tape can be sewn easily on most fabrics – adhesive is required to bond onto substrates which cannot be sewn, such as metal, glass, concrete, wood, ceramic, rigid plastics, etc.
Solvent borne, water borne, and hot melt pressure sensitive adhesives are all used for fastening tapes. However, HMPSA (hot melt pressure sensitive adhesive) is the most favorable adhesive because it offers the following advantages:
- Environmental friendly – No solvent evaporation and waste water generated from entire hot melt coating system.
- High coating weight – Typical coating thickness for a fastening tape is 200-250 microns. It is very difficult to obtain such high coating weight from solvent and water borne adhesives at one shot. The maximum coating weight for HMPSA on fastening tapes can easily reach 500 microns.
- Fast coating speed – HMPSA does not require a drying oven during process. It cools and sets right after coating by a series of cooling fans. A release paper is laminated on the sticky adhesive surface immediately after coating. The coating speed for a typical 1 inch wide tape is about 100 ft/minute.
- Controlled coating width – To avoid edge-ooze of the thick and sticky surface, a slot coating die with a precise width is generally used. No adhesive is coated at both edges of the fastening tape for about 0.5-1 mm.
There is no universal HMPSA for all fastening tapes. Depending upon specific application areas, to introduce HMPSAs imparting different adhesion performances are normally required. For those applications requiring high temperature resistant, such as automotive, curable solvent or water borne adhesives are needed.