SolutionsWhat Are Pressure-Sensitive Adhesives?

Pressure-Sensitive Adhesives (PSA) are a non-reactive type of adhesive that is tacky at room temperature. They only require the application of light pressure to secure the adhesive to the desired surface, so there is no need to activate them with water, solvent, or heat. PSAs can be removable, semi-permanent, or permanent. Substrates like paper, plastic, glass, wood, cement, and metal are all appropriate for pressure-sensitive tape or pressure-sensitive glue.

How Do Pressure-Sensitive Adhesives Work?

Typically made up of rubber and acrylics (synthetic resins), pressure-sensitive adhesives work by achieving the correct balance between flow and resistance to flow. A bond forms 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 subjected to 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, also play a role.

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.

Pressure-sensitive adhesives can be used for:

• Rigid packaging, adhering to the most difficult stock​
• Non-woven or disposable hygiene products​
• Labeling on bottles and cans ​
• Graphic arts and bookbinding for joint and side glue​
• Tape and film manufacturing​
• Fugitive adhesives that create a temporary bond and allow materials to be easily separated
• Laminating and roll coating

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; the most conformable, extendable option and can be made in 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 is 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 setup 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

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, food and beverage manufacturing, pet food packaging, appliance manufacturing, mattress manufacturing, and more. Reevaluating 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.