Pressure sensitive adhesives, or PSAs, are sticky substances that bond to surfaces with just a bit of pressure–no heat, water, or extra steps needed. They’re the reason labels, stickers, and tape stick so easily. From sealing packages to creating medical bandages, PSAs are used everywhere because they’re simple, quick, and effective.
Whether you’re taping a box, sticking a label on a jar, or mounting something on a wall, PSAs make the process fast and hassle-free. In this guide, we’ll explain more about what pressure sensitive adhesives are, how they’re made, and how to best use them.
What Are They?
Pressure sensitive adhesives form a bond when pressure is applied. Unlike other types of adhesives, PSAs don’t require heat, water, or solvents to activate the adhesive properties. This makes them very convenient for numerous applications.
PSAs are viscoelastic, which gives them both viscous and elastic properties. This makes them soft enough to flow into surface irregularities and strong enough to hold the bond under stress. Bonds form as soon as pressure is applied without additional curing time. Some PSAs are even designed to be removable and repositionable without leaving residue.
How Are They Made?
Pressure sensitive adhesives are made using different methods, depending on their type: solvent-based, water-based, hot-melt, or UV-curable. Each method creates adhesives with specific features. Here’s how they are made:
- Solvent-based PSAs: Solvent-based PSAs are made when sticky materials like rubber or acrylic are mixed with a solvent. This creates a smooth, liquid adhesive. The liquid is spread onto a backing, like tape or fabric, and heat is used to evaporate the solvent, leaving behind the adhesive layer. These types of PSAs stick really well to many surfaces and are often great for tough jobs in need of a strong bond.
- Water-based PSAs: This method uses water instead of chemicals to mix the ingredients, making it a more eco-friendly option. To make water-based PSAs, polymers and tackifiers are blended with water to form a creamy mixture. The liquid is spread onto the backing, and heat is used to dry out the water. Water-based pressure sensitive adhesives are generally safer for the environment, but don’t work as well in wet or extreme conditions.
- Hot-melt PSAS: Hot-melt PSAs start as solid adhesives that turn liquid when heated, and harden as they cool. They’re made by melting the base ingredients into a gooey adhesive. The hot adhesive is spread onto the backing or applied directly to the surfaces. As it cools, it hardens and forms a strong bond. Hot-melt pressure sensitive adhesives are quick and mess-free, but can’t handle very high temperatures.
- UV-curable PSAs: These adhesives are made to harden instantly when exposed to UV light. To make UV-curable PSAs, the tacky ingredients are mixed into a liquid adhesive, which is spread onto the backing or applied to a surface. The PSA is exposed to UV light, which makes it harden instantly.
Best Uses
Pressure sensitive adhesives are widely used in a number of industries, especially for labels and tapes. Here are some of the best uses of pressure sensitive adhesives:
- Shipping labels: Labels with PSAs are used for address labels, barcodes, and shipping instructions.
- Branding: Adhesive-backed labels are ideal for branding products like bottles, jars, and boxes.
- Safety labels: Labels with durable pressure sensitive adhesives can be used on machinery or equipment to provide warnings or instructions that will last through tough conditions.
- Promotional stickers: Stickers with PSAs can be used for temporary branding or special offers. Repositionable PSAs are especially valuable here.
- Asset tracking labels: Durable PSA labels with barcodes or QR codes help in managing inventory and tracking assets.
- Packing tape: Packing tapes with PSAs are widely used for sealing boxes and cartons in shipping and storage.
- Electrical tape: Electrical tapes with PSAs provide insulation and protection in electrical wiring.
- Medical tapes: PSA tapes like surgical and athletic tapes are used to secure bandages or provide support.
- Automotive: The automotive industry uses double-sided and foam tapes for bonding trims, emblems, and panels.
Different Types
There are a number of different types of PSA products made for specific uses. Here are the four main types of pressure sensitive adhesives;
- Adhesive tape: This is the most common type of PSA product, and it’s what most people think of when they hear “tape.” Adhesive tape is a strip of material, such as plastic or paper, with an adhesive on one side. It’s used to seal boxes, fix things temporarily, and wrap cables or protect surfaces. Examples include duct tape, masking tape, or packing tape.
- Single-faced product: Similar to adhesive tape, single-faced products have adhesive on one side. The other side usually has graphics or text. Examples include labels and stickers.
- Double-faced product: Double-faced products are a kind of tape that have adhesive on both sides, with a carrier membrane in between. They’re used to mount items on walls, craft or assemble products, or install carpet. Examples include double-sided tape or carpet tape.
- Transfer tape: Transfer tape is a special kind of tape where only the adhesive transfers to the surface–no actual backing material is left behind. This can be used to create permanent bonds in crafts and manufacturing without the added bulk of a carrier membrane. Examples include transfer adhesives used in signage or laminating.
What Materials Are They Made of?
Pressure sensitive adhesives are made from three main base polymers: rubber, acrylic, and silicone. Each has unique properties that affect the adhesive:
- Rubber/resin-based PSAs: These are made from a mix of rubber and resins and made using the hot-melt or solvent-based method. Rubber-based PSAs are known for their strong initial tack and bond strength, providing good adhesion on a variety of surfaces. They’re generally the most cost-effective types of PSAs.
- Acrylic PSAs: Acrylic PSAs are made from acrylic polymers. They offer excellent durability and weather resistance, making them best for outdoor applications and applications that require long-term use. Although they are durable, acrylic PSAs are usually not as strong as those made from rubber. They’re also more expensive than rubber PSAs.
- Silicone PSAs: Made with silicone polymers, silicone PSAs are highly resilient, especially under high temperatures and harsh environments. They’re best for electronics, medical devices, and automotive uses, and bond well to low-energy surfaces like PTFE plastics. Although they resist heat and chemicals well, silicone PSAs are usually expensive and have lower initial tack than rubber or acrylic PSAS.
Pressure Sensitive Adhesives Conclusion
Pressure sensitive adhesives come in a variety of forms, depending on your specific needs. Whether you need them for sealing, mounting, or creating clean bonds, PSAs are easy to apply and versatile.
At Coast Label, we understand how best to use the unique properties of PSAs. We can manufacture custom labels and tapes based on the unique needs of your company. Contact us today for a proposal!
