Your Complete Guide to Pressure-Sensitive Adhesives

History shows time and again that the best innovations are developed in the face of the most formidable obstacles. In addition to affecting nearly every aspect of consumers’ lives, research shows that the global COVID-19 pandemic has also significantly impacted product manufacturing across all industries. Although many product developers, executives, and marketers have been working from home during the pandemic, they have not neglected their commitment to their consumers. Instead, these teams have chosen to take this challenge as an opportunity to introduce new products such as pressure-sensitive adhesives and improve existing favorites, allowing them to emerge from this situation in a stronger position to satisfy their market base.

The pandemic has been particularly influential on the food and beverage industries. In fact, half of industry leaders are confident in the ability of food and beverage manufacturers to make an impressive leap forward during this “new normal” and return more capable than ever. At the same time, consumer necessity has driven sales growth for manufacturers, and it has also emphasized the importance of implementing high-quality packaging for their products. Because virtually every industry requires effective solutions for packing and sealing their products, the demand for adhesives and sealants in the global economy has surged.

Consider the information below to learn about PSAs, how they work, and the many advantages they offer your business. Then contact APPLIED Adhesives today to discover how we can upgrade your brand with a customized adhesive solution.

What Are PSAs?

Adhesives are divided into two primary categories: structural and pressure-sensitive. Structural adhesives harden to form permanent bonds, either by evaporation of a solvent, chemical reactions, reaction with UV radiation, or cooling processes. They become part of the structure of the materials assembled and can include acrylics, urethanes, thermoplastics, and epoxies, among others.

By contrast, pressure-sensitive adhesives are a non-reactive type of adhesive that only requires the application of light pressure to secure the adhesive to the desired surface. They do not need solvent, water, or heat to activate this bond and can be used for removable, semi-permanent, or permanent applications. The bond will form and securely hold to a variety of substrates, including plastic, glass, wood, paper, metal, and cement. Pressure-sensitive adhesives can include natural rubber, synthetic rubber, acrylic, and silicone PSAs.

How Do PSAs Work?

Typically made up of rubber and acrylics (synthetic resins), pressure-sensitive adhesives work by achieving the correct balance between flow and the resistance to flow. Forming a bond occurs because the adhesive is viscous and elastic. As a result, it may flow (or wet) the substrate surface on contact rather than transforming into a solid material. The strength of this bond depends on the adhesive’s resistance to flow when met with stress and the amount of pressure used when applying the adhesive to the substrate surface. Surface factors, including smoothness, surface energy, and the presence or absence of contaminants, play a role as well.

Pressure-sensitive adhesives can be designed for removable or permanent application, depending on the needs of the manufacturer and the uses of the product. Removable adhesives form temporary bonds, can be designed to stick and unstick repeatedly, and do not leave behind a residue after removal. Permanent adhesives begin with a temporary bond and change their properties over several hours or days to form a permanent bond, either by becoming less viscous or by increasing the strength of the bond.

PSA Constructions

Pressure-sensitive adhesives are available in four different product constructions, and choosing the best one depends on the specific application and its bonding requirements.

  1. Adhesive tape – does not feature a liner and winds around itself, like duct tape, masking tape, and electrician’s tape.
  2. One-side coated or single-faced product – adhesive is applied to one side of the product’s carrier membrane and protected by a liner that is removed before application; used for labels, graphics, overlaminates, or any other application requiring the adhesive to be printable, decorative, or utilized in protecting a surface.
  3. Two-side coated or double-faced product – adhesive is applied to both sides of the product’s carrier membrane and protected by a liner; different forms of adhesive can be applied on either side of the product.
  4. Transfer tape or free film – consists of a strip of adhesive that allows bonding between two substrates without requiring a carrier membrane for reinforcement; most conformable, extendable option and can be made of varying thicknesses.

Pressure-Sensitive Adhesive Manufacturing

When it comes to manufacturing the above PSA products for use in packaging and labeling, there are four major chemistries involved:

  1. Hot-melts. Usually formed from a mixture of thermoplastic rubber, resins, and plasticizers, hot-melts come in solid form at room temperature and are heated until proper flow is achieved. Then, they can either be extruded or formed into a web and rolled without the need to dry.
  2. Solvent-based. Either rubber or acrylic are dissolved into a solvent before coating onto a web. The solvent is evaporated before winding into a roll.
  3. Emulsion (Water-based). These liquid PSAs form when rubbers or acrylics are dispersed into water before forming a web. The water is then evaporated before rolling the final product.
  4. UV-cured. Unlike the other forms of PSA products, UV curable PSAs require no mixing or drying. Instead, brief exposure to UV light allows curing within seconds without the use of heated air.

Advantages of Pressure-Sensitive Adhesives

Pressure-sensitive adhesives offer multiple advantages over other sealants and adhesives, including:

  • Easily automated application that does not need elaborate equipment
  • Does not require lengthy set-up or curing times like liquid adhesives
  • Immediate adhesion allows the manufacturing process to continue without interruption
  • Significantly saves time and labor costs
  • Eliminates the need for mechanical fasteners, such as screws or clips, which prevents the development of cracks and corrosion
  • Improves the appearance and integrity of the final product
  • Creates an insulating seal, a necessity for food and beverage industries
  • Offers sound and vibration control

Are PSAs Right for Your Packaging Needs?

APPLIED Adhesives has created customized solutions for the unique needs of companies within all types of industries, offering low-risk opportunities for improvement without sacrificing production time. A recent case study involves a national manufacturer that wanted to update its paper labeling on glass jars to clear poly labels while ensuring the adhesive was not visible through the new labels. Our Technical Services team completed an in-depth analysis of the current adhesive to identify performance issues, then reviewed the technical data provided by our product lines to discover the ideal solution for their unique needs.

Customized testing procedures were set up to imitate the actual production conditions of the manufacturer, placing labels in specialized equipment that simulates tensile forces. In addition to examining the primary concern of visibility, these tests also assessed lap bond strength and pickup bond strength. Hot-melt PSAs were the perfect choice, both for the current paper labels and the proposed poly labels. Using a single product for both labeling options allowed the manufacturer to decrease inventory requirements and eliminate the need for separate tanks, improving productivity without increasing overall cost.

Contact Us Today

APPLIED Adhesives understands the importance of packaging considerations in ensuring your manufacturing operations run as smoothly and efficiently as possible. We offer an extensive selection of pressure-sensitive adhesives for industries of all kinds, including bookbinding, paper products, beverage and food manufacturers, pet food packaging, appliance, mattress manufacturers, and more. Revisiting your adhesive choices can help you improve your shelf appeal, line performance, field performance, temperature resistance, and cost.

Contact APPLIED Adhesives today to learn more about our product offerings and discuss how we can create the perfect solution for your business needs.