Hot Melt Adhesives

Thermoplastic Polymers

Hot melt adhesives are formulated from a variety of thermoplastic polymers. Each polymer has its own properties and benefits. Thermoplastic polymers are solid at room temperature and become liquid when heated. Most of the thermoplastic polymers used to make hot melt adhesives become molten at relatively low temperatures (above 80˚C). This helps to protect heat sensitive substrates.

Henkel pioneered a line of low application temperature adhesives known as TECHNOMELT^® COOL. Initially designed to work with heat sensitive applications, low temperature hot melt adhesives offer the added benefit of improving worker safety with reduced burn risks to employees on production lines. The lower operating temperatures also reduce energy consumption and offer sustainability benefits at manufacturing sites. Many manufacturers adopted TECHNOMELT^® COOL as a preferred general-purpose hot melt adhesive solution for applications requiring standard heat resistance. 

As factory footprints shrink in size and line speeds increase to keep up with growth and equipment advancements, hot melt adhesives continue to adapt. Henkel meets these new requirements with TECHNOMELT^® SUPRA, a range of high-performance adhesives. When metallocene catalyzed polymers were introduced, Henkel further enhanced the TECHNOMELT^® SUPRA line with adhesives that increase stability, achieve longer pot lives, deliver less downtime and char, and result in less machine maintenance. TECHNOMELT^® SUPRA products are more robust than previous technologies and can withstand greater temperature extremes resulting in fewer pop opens. Additionally, they support faster set speeds and longer open times, making them more suitable for more complex operations with faster equipment.

Henkel’s TECHNOMELT SUPRA PRO^® offers different thermoplastic polymers specially tailored for food packaging applications. Within this product line, there are several high-performance hot melt adhesives available for different food packaging substrates all while supporting increased production efficiency.

Polyamide-Based Holt Melt Adhesives

Polyamide-based hot melt adhesives offer excellent resistance to heat, oil, grease, plasticizers, and solvents. They are also very strong and flexible. These qualities make them a good choice for difficult to bond, low energy substrates.  Polyamide-based hot melt adhesives are generally used in electronics, filtration, automotive, and aerospace applications due to their high heat and chemical resistance properties.

TECHNOMELT^® PA hot melt adhesives offer beneficial characteristic properties necessary to excel in demanding performance environments. They have higher thermal stability and good chemical resistance to common solvents, plasticizers, and oils. TECHNOMELT^® PA adhesives have higher creep resistance under load and better heat resistance with thermally stability up to 160°C.

TECHNOMELT^® PA provides protection for modern electronic components, printed circuit boards (PCBs), and lighting applications. The product family delivers electrical insulation, as well as temperature, vibration and solvent resistance for many applications. These products protect electronics from the harshest environmental conditions, including high humidity, long-term UV exposure and extreme thermal cycling. TECHNOMELT^® PA also supports low pressure molding, which is a faster and more efficient process than conventional potting. The products range includes one-part material – no mixing or curing – and reduces material consumption through streamlined, multi-level, contour-exact encapsulation. This is a sustainable option with its green chemistry and reusable formulation.

Polyamide-based hot melt adhesives have high cohesive strength with strong inter-chain hydrogen bonds, which is the reason for their relative high strength and chemical resistance properties. TECHNOMELT^® PA formulations offer a flexible open time from a few seconds up to about a minute and provide excellent adhesion to a wide variety of substrates including metal, paper, wood, and many plastics such as PVC and surface-treated polypropylene and polyethylene. Polyamide hot melt adhesives are also used for bonding textile fabrics because they have good resistance to dry cleaning fluids. Other important applications include furniture assembly, shoe making, automotive assembly, and gas/oil filter bonding.

Polyurethane-Based Hot Melt Adhesives

Polyurethane-based hot melt adhesives are one of the oldest hot melt technologies around. They provide excellent thermal stability and work especially well for case, carton, and tray sealing applications. Henkel’s PUR hot melt adhesives are flexible and withstand a range of thermal settings. They are particularly suitable for automotive, building materials, and bookbinding due to their strong adhesive bonding capabilities.

TECHNOMELT^® PUR adhesives have greater bond strength. PUR adhesives polymerize when in contact with the moisture in the air enabling the formation of stronger bonds after the curing process is complete. Additionally, PUR hot melt adhesives have a low volatile organic compound (VOC) content compared to traditional hot melt materials. Lower VOCs also reduce environmental impacts.

Some PUR hot melt adhesives have faster set times and a lower need for having drying and ventilation equipment. Most PUR adhesives also require 24 hours to completely cure. The adhesive strength continues to increase from reactions with the moisture in the air.

Bio-based Hot Melt Adhesives

Henkel is at the forefront of developing bio-based hot melt adhesive technology specifically suited for sustainability and circular economy uses. This is in response to increasing industry interest in these types of formulations to help reduce dependency on petroleum-based raw materials while the reducing carbon footprint of manufacturing operations. As a leading developer of these bio-based hot melt adhesive chemistries, Henkel is looking improve the way companies better their sustainable packaging initiatives.

Learn about the hot melt adhesive products we offer and ask industry specific questions about this type of adhesive by contacting a member of our team or using the contact form below.

Hot Melt Pellets and Pastilles

Pellets and pastilles are common forms of hot melt adhesives. They are best suited for applications where rapid melting is necessary to keep the manufacturing process running at a high pace. These small pebble-like adhesives are packaged in various forms and can be used with auto-feeding systems to improve efficiency on production lines. Hot melt pellets and pastilles are melted and applied using nozzles, which can place a bead, line, or spray the adhesive on the substrate.

Hot Melt Adhesive EASYMELT^® Chubs

Similar to hot melt blocks, another common product form is a hot melt chub. This product was developed to integrate faster into molten form in a hot melt tank. Henkel invented a chub form – EASYMELT^® – which is a 1 Kilo (2.2-pound) solid chub with an integral film wrapper. The wrapper, which melts in with the adhesive, makes the product convenient to handle and substantially reduces packaging waste.

EASYFLOW^® Hot Melt Adhesive System

EASYFLOW^® is a patented, adhesive in small, non-sticky mini chub form. This unique form enables auto feeding of TECHNOMELT^® DM adhesives into hot melt tanks, improving production line efficiency while manufacturing disposable hygiene products and minimizing downtime and material handling. Mini in size, EASYFLOW^® is highly effective when it comes to performance and efficiency. EASYFLOW^® brings three main benefits for consumer goods manufacturers to keep productions lines moving while reducing downtime:

• Auto-feeding
• Closed system
• Melt on demand

Produced with a protective coating, the adhesive is delivered in small, light, non-sticky, and easy to handle mini chubs. The protective coating does not affect the application or end-performance of the adhesive. The coating is 100% compatible with the adhesive and it will not separate in the hot melt tanks. This unique product form helps establish a robust production line to support improved efficiency, resolve application issues, and make it easier for line operators.

Hot Melt Drums

Hot melt drums are the largest product form for hot melt adhesives. Intended to handle high volume production of hot melt PSA and PUR adhesives, these adhesives are often found in 200-liter (55-gallon) containers. This product form is designed to work with drum unloader equipment on manufacturing lines.

Hot Melt Blocks

Hot melt blocks are commonly used for bonding and coating polyethylene terephthalate, polyethylene, and other polyolefins. The blocks are commonly placed in hot melt tanks to become molten and applied with specialized dispensing nozzles to the substrate.

Hot Melt Spray Application

Hot melt adhesive spray application is fast, efficient, and effective. Hot melt spray adhesives are dispensed by manipulating a continuous bead of adhesive into a pattern with compressed air. To maximize machine uptime, it is necessary to monitor application and avoid common process challenges, including:

• Poor coverage – Adhesive gaps/voids exist rather than uniform coating of the substrate
• Bleed-through – Adhesive seeps through the substrate and contacts the underlying surface
• Poor intermittent performance – Adhesive trails form between the spray patterns

Using a hot melt spray system nozzle, the adhesives begin to cool and set. The method is ideal for large surface areas.

Hot Melt Slot Coating Application

In hot melt slot coating, a layer of hot melt adhesive is applied to the substrate before being cooled and solidified. Hot melt slot coating is often used when working with pressure-sensitive adhesives on thin substrates.

Hot Melt Bead and Line Application

For hot melt bead or line applications, the nozzle fires a specific amount of adhesive and then is cut off before firing again. This method is often used when an adhesive is needed in a specific spot and can be compressed quickly. Similar to spray applications, as soon as the adhesive is dispensed, it begins to cool. In utilizing this application, it is important to understand the set speed for the application to avoid bonding issues.