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PSAs Changing to Meet New Graphic Market Needs

Posted on 10/26/2021 11:00:06 AM By ASC
  

Choosing the right pressure-sensitive adhesive to adhere graphic products is becoming  more important as the range of PSAs grows along with increasing  changes and needs in the graphic market, which include the materials used, the film itself, and the size and type of applications as the market expands from in-store point-of-purchase promotions; advertising posters (in and outdoors; colorful  graphics; labeling on buses, vans, and other vehicles; to traffic and safety markings on the road to new sectors and applications with different needs. These include architecture, which is already using graphics for outdoor color facings, and is considered likely to move indoors with wall coverings and other interior decor soon.

PSA choice for particular graphic applications is dependent on how permanent the application will be;its expected life span; and environmental conditions, which in turn determines the needs in terms of initial tack; peel retention; optical clarity; shrink; as well as water and plasticizer migration resistance.  Making the situation more challenging is the change in materials used for graphic films, with new substrates and materials such as semi-flexible olefin added to the traditional plastics, polymers, paper and textiles used for films and sheets.

While other PSAs use rubber or silicone base chemistry, adhesives for graphic films are generally based on a blend of acrylic monomers and other compounds for better performance, and are grouped into four adhesion categories based on how removable they are.

Ultra-removable adhesives (usually used on paper-based applications) can be removed and reapplied many times without losing initial tack. The slightly larger particles in these PSAs (produced with advanced microsphere technology) provide clean removability from most substrates, and form a discontinuous adhesive film with a low glass transition temperature and low peel value.

Removable PSAs include differing adhesive levels to meet the needs of various  graphic films. Low-adhesion PSAs feature clean removability from different surfaces, are UV and moisture resistant  which reduces the water damage and yellowing which can affect clarity; and those that are plasticizer-resistant withstand softening effects which could compromise performance.

Permanent PSAs provide higher adhesion to substrates, withstand environmental conditions, and have high shrink resistance for high-quality graphic products. This makes them suitable for with long service life graphics like decorative films in offices and conference rooms,and architectural decals and signage. Two PSA formulations for use in long-life applications are crosslinked. One provides superior balance of peal and shear, has good bond strength and cohesion, and plasticizer resistance which has led to FDA approval for indirect food contact. The other one adds in strong water and blush resistance, and high-performance shear to the benefits of the first. It is also tackified specifically for low-surface-energy substrates and opaque films where clarity isn’t vital, and has not only been approved by the FDA for indirect food contact, but is also compliant for both direct skin, and direct skin and oral toxicity.

High-tack PSAs are the best solution for applications requiring maximum durability when substrates are low-energy and hard to bond. When environmental conditions are rugged, water-based high performance pressure sensitive adhesives are the right ones for the job. Important properties for choosing a high-tack PSA include strong thumb appeal or initial tack, and good balance of peel and shear values which include high bond strength and cohesion. These PSAs perform well on multiple substrates, and specially well on those with low surface energy, and can be BS5609 compliant for durable goods.