Disadvantages of acrylic pressure sensitive adhesives

The advantages of acrylic pressure-sensitive adhesives are well-known in the prior art. Many examples of acrylic Pressure Sensitive Adhesives are described in Pressure Sensitive Adhesives Technology, 1st Ed., 1996, IstvanBenedek and LucJHeymans. However, ordinary acrylic pressure-sensitive adhesives (PSA) have two major disadvantages.

One disadvantage is the relatively poor adhesion to low surface energy substrates, although they have very good adhesion to many high surface energy substrates. This is because acrylic PSA generally has higher surface energy and higher polarity. Over the past few years, the use of low surface energy materials such as polyolefin and foam plastics has increased significantly, and many applications of PSA products require good adhesion to low surface energy substrates. Therefore, there exists an acrylic PSA with good adhesion not only to high surface energy substrates but also to low surface energy substrates in great demand.

The second disadvantage is the relatively low viscosity, especially of acrylic PSA with high shear resistance. Acrylic PSA is difficult to have high viscosity and high shear resistance at the same time because increased viscosity usually reduces shear resistance. However, many high-end applications require PSA to have both high shear resistance and high viscosity.

JP6-322355 discloses water-soluble or water-dispersed pressure-sensitive binders containing water-soluble polyether polyols and water-soluble base polymers such as polyacrylates carrying sulfonates. The role of polyols in JP6-322355 is simply used for plasticizing base polymers. This type of acrylic pressure-sensitive adhesive inherently has very poor water or moisture resistance and is therefore not suitable for most PSA applications. In addition, like other common acrylic pressure-sensitive adhesives, these adhesives have low viscosity and do not have good adhesion to low surface energy substrates.