Adhesive Converting Blog

Your Guide to Heat Activated Adhesives

Posted by Sue Chambers Mar 26, 2020 9:30:00 AM

A heat activated adhesive is a type of adheive, usually applied to a tape backing, that will not bond at normal temperatures. Instead, it becomes sticky in certain temperatures, wherein the adhesive chemicals are activated and can form a bond.

These tapes are extremely versatile and can be used for bonding in a huge variety of projects. Join us, today, as we dive deep into heat activated adhesive, its uses, benefits, alternatives, and how it all works.

What Is Heat Activated Adhesive?

Let's start today's article off with a basic explanation of heat activated adhesives. As the name implies, this is a non-sticky adhesive that, usually, will not bond or adhere at normal temperatures. As part of its design, this adhesive only begins to bond when heated to a very specific temperature.

Heat activated adhesive films offer a lot of versatility in their design and application. They are industrial in scope and have actually grown extensively in popularity over the last few decades.

When activated from a heat source, your adhesive goes through two stages:

  • Phase one occurs takes place within seconds of the heat activation process. Bonding occurs between the two objects and the adhesive tape itself begins to cool after being heated. 

  • The second phase of the process is carried out over the next few minutes. Once the adhesive has had chance to cool down, the chemicals on the tape start crystallizing. This increases the strength of the material bond significantly.

One of the big draws to heat activated adhesives is that it is completely dry before being heated. There is no tackiness, and it will not stick to itself, making it incredibly easy to work into various cracks and crevices without major hassle. The tape itself feels like paper and only becomes sticky under heated conditions.

Adhesive films use thin layers of specifically designed bonding agents attached to some sort of backing material to get the job done. This gives you, the user, a product that is equal parts easy to use and extremely versatile. Backings can be coated with the adhesive on one or both sides. They may also be treated with different concentrations of the same adhesive. This makes them more or less appropriate for different tasks.

Moreover, these backings may actually be created from a range of materials. Depending on your needs and supplier, you might find any of the following as your heat activated adhesive backing:

  • cloth
  • foam
  • foil
  • paper
  • plastic

...as well as a host of others. The aim, with these, is to provide enough room to use heat adhesives in a range of environments. You'll find tapes cut and wound into rolls, for easy use and storage.

Heat-activated adhesives are available in configurations for any job you can imagine. Suitable for materials from plastic to metal and wood, there's very little you can't actually join with a good heat activated adhesive.

More Characteristics 

Heat activated film brings a range of useful traits to the table, including some of the following:

  • resistance to aging and weathering
  • improved shock resistance
  • extreme flexibility
  • available in a range of thicknesses and designs
  • incredibly high bonding strength
  • improved resistance to chemicals
  • extremely stable in high temperatures
  • elasticity under various conditions
  • the availability of electrically conductive variants

As a leading adhesive across various industries, heat activated films deserve their reputation. The adhesive itself is designed for temperatures from 40 to 140 degrees, C. Depending on where you go, adhesives are also made in a variety of grades. Looking for an improved flammability rating? Expecting more from your web grade? There's something out there for you.

Different Types Of Adhesive Tape

Of course, heat activated tape isn't the only variety out there. Let's take a closer look at the three main types of adhesive tape, in general, so we can compare their benefits:

Pressure Sensitive Adhesive Film

Otherwise known as "PSA", pressure-sensitive adhesives use chemicals that activate under pressure. This is what many of us think of when we think of traditional adhesive tape. A film that consists of pressure sensitive adhesive applied to some sort of substrate, typically on one side. The other side of the tape's backing usually features a release liner that makes manual pressure applications easier. 

You'll PSAs sticky at room temperature, making them quick to prepare and to apply. They can be used to bond various materials, from paper and plastic to metal and concrete in some cases. They work better in temperatures from 59 to 95ºF. At a lower temperature, you may run into wetting or adhesion issues with the actual substrate itself. Alternatively, if used in extremely high temperatures, the tape itself may stretch or warp, presenting problems during the final application.

In terms of bonding pressure, expect around 30 psi from this adhesive, depending on the specific application you are using it for.

Heat Activated Adhesive Film

With so many options of tape available, heated, pressure sensitive, and not, it should be noted that heat activated pressure sensitive adhesive exists. For the purposes of simplicity, however, we'll just be looking at heated options, today.

Heat activated films are a different animal to pressure sensitive tape. Unlike the latter, heat activated adhesive are completely dry until activated by the titular heat. That means they are not tacky, will not stick to the user or themselves, and can be applied in whatever configuration they need to be.

For proper adhesion, the film has to be kept at a high temperature, typically anywhere above 180º F, for a very specific period of time. This is useful because it is so specific, meaning there is zero change of accidentally activating the tape before you are ready to use it.

While the tape is cooling after being heated, the adhesive's microstructure begins to crystallize, boosting its overall bond strength significantly. This strength is important to the overall utility of these tapes. With thermally activated adhesives, they are particularly aggressive, and their adhesion allows for difficult surfaces to be joined with minimal issues. These can include notoriously tricky substrates, such as rubber and other polymer based materials.

As a last note, heat activated adhesives are also very customizable and can be combined with various backing materials to achieve different results.

Moisture Activated Adhesive Film

Where pressure sensitive tape requires the application of pressure, and heat is require for heat activated adhesive films, moisture is activated in wet conditions. Here, the adhesive compound becomes sticky when wet with water or any other approved liquid solution.

This is less of an industrial option than the other adhesives on this list, and is generally much less expensive. Users will find this adhesive film backed with kraft paper, and it is generally used for more lightweight projects.

What Are Some Of The Other Benefits Of Heat Activated Adhesive?

Heat activated adhesive tapes are mostly popular for their relatively high bonding strength. This is a strong bond with an even application and, as we've described, is often used for binding tricky substrates that other chemicals just don't work on.

Improved chemical resistance is another big factor. The crosslinking reaction that occurs while the thermoset adhesives are curing makes for a far more robust bonding structure that you just don't find elsewhere. Pressure sensitive and moisture films have their place, but they can't compete when it comes to bonding strength.

Not only is it stronger than alternative adhesives, but it also works on surfaces those films just aren't compatible with. Adhesion on these surfaces simply isn't an option, usually, but the added bonding strength and maneuverability of heat films give them a decisive edge. Look to heat activation for work with the following materials:

  • Aluminum foil
  • Polyurethane
  • PVC
  • Rubber

As a result of this compatibility, thermally activated adhesives are also used in a wider variety of industries. Laminating, forming and thermoplastic welding all have their uses for this tape, among many others. One industry that has seen a lot of play in this regard is the textile industry, where heat-activated adhesives combine extremely well with various fabrics. This, in turn, means it can be used to make various high-performance composites, giving designers the tools they need to build anything they want.

More practically, these same textile designers were able to incorporate this film into their waterproof garments. Sealing their garments quicker and more easily than ever before,  heat activated adhesive films found a place in this community early on. Add to that the fact that it is washing machine durable, and it's a no brainer why this would be popular in textile work.

Of course, the benefits of this kind of adhesive go much further than that. It starts with versatility, with the tape itself designed for rigid or flexible applications. This is why it's seen so much success in different industries, as the applications are far-ranging and varied.

It's also excellent for induction curing and sealing. This makes it appropriate in high-pressure applications, shoring up leaks and curing surfaces quickly and easily.

Applications For This Adhesive

Using a combination of specifically designed tapes and heat activated adhesives, it's possible to achieve a variety of great results. These tapes can be used to bond to weather strip seals, with their high durability and weatherproof design. This makes it a perfect addition to any home repair toolkit and one of a repairman's best friends.

While we're at it, throw gaskets and other elastomeric materials for automotive and industrial applications in there, as well. Worked into tight spacing, the maneuverability of heat tape also means it can be used in any of the unpredictable places where problems might develop. This is a big selling point, especially when compared to pressure sensitive tapes, which need to be pressed into place and may stick to themselves.

It's also a strong option for some of the following materials:

  • polypropylene
  • polyethylene
  • polyester
  • nylon
  • paper
  • ceramic
  • wood
  • fiber materials

This makes it a clear winner for industries where different materials are regularly brought into play. Across the adhesive industry, what matters most isn't always adhesive strength, but the ability to join a variety of materials. And heat activated pulls ahead every time.

With permanent solvent acrylic adhesive that prioritizes heating, we find that extremely low initial tack we've mentioned a few times in this article already. This means that, whatever substrates you're working with, you can reposition it properly before applying heat. That makes this feature a perfect choice for delicate printing, display mounting, and insulation.

With the right heat activated adhesive, what you're making is more an engineering solution than anything else. These coatings will actively adhere to hard-to-stick, making them surprisingly good for repair work, as well. Add to that their high temperature rating, and these adhesives stand up well in harsh environments as well.

Heat Activated Adhesive

Ultimately, heat activated adhesive is one of the most versatile, useful options for joining literally any substrates out there. For more minor work, arts and crafts and casual adhesion around the house, it may be like bringing a grenade to a fistfight. But, in terms of high-end, industrial joining, it's difficult to beat in literally any way.

Apply a piece of heat tape to a flat surface, and you're off to the races in a matter of minutes. More importantly, work that tape into a cramped space with awkward corners, and you can apply it to basically any area you want. 

And the versatility cannot be understated. Looking for a tight join that won't come apart under high pressure? This is a perfect option. Want something that allows for high heat, or allows you to wash the material multiple times? This tape is used extensively in industries that require exactly the same things. 

With so many possibilities available to you, heat activated adhesive films do a lot to let you use them in any and all situations. 

Looking for more great insights into this and other varieties of high-end adhesive tape? Get in touch with us, today, or check out some of our other expert blogs for everything you need and more!

Sue Chambers

Written by Sue Chambers

President and CEO of Strouse