Even if Styrene Block Copolymers (SBCs) are the most
common polymer base to formulate pressure sensitive hot-melts, Ethylene
Copolymers can also be a good choice, being able to match highly demanding
technical requirements both for some diapers applications or fem care
products.
In this type of adhesive, the flexibility provided by
a high content of Vinyl Acetate or Acrylate (more than 30%) is enhanced
by adding a plasticizer, which ensures the "sticky" effect at
an ambient temperature.
Ethylene copolymer based HMPSA can provide very high
adhesion on difficult substrates such as untreated polyolefins or various
plastics as well as high color stability in water white or white formulations.
For "positioning hot-melt" in fem-care products,
adhesion of ethylene copolymers based HMPSA can be adjusted to a precise
value while keeping high internal cohesion to avoid any adhesive transfer
onto the fabric. High coplymer content and high MFI copolymers are preffered as they present a lower glass transition temperature as well
as a lower cristallinity.
