Hot Melt Adhesive
Polyurethane Reactive

Hot Melt Adhesive

Hot melt adhesive is a 100% thermoplastic base that requires heated temperature to melt flow the glue into a molten state for bonding and sealing before turning to a solid-state when cooled. Hot melt adhesives have long shelf life and usually can be disposed of without special precautions.

In most industrial applications, hot melt adhesives (HMA) provide merits over the solvent glues as the level Volatile Organic Compounds emitted from it is high. With hot melt usage, the setting time and worklife is significantly reduced without the use of any force drying and in a way speed up the production process and ease of application. 

Some of the common base materials that are used to produce hot melts include

  • Ethylene-vinyl acetate (EVA) copolymers, low-performance, low-cost, and most common material for the glue sticks. They provide sufficient strength between 30 and 50 °C but are limited to use below 60–80 °C .
  • Polyolefins (PO), low-performance, for difficult-to-bond plastics. Very good adhesion to polypropylene, good moisture barrier, chemical resistance against polar solvents and solutions of acids, bases, and alcohols. Longer open time in comparison with EVA and polyamides.
  • Amorphous polyolefin (APO/APAO) hot melts have good fuel and acid resistance, moderate heat resistance, are tacky, soft and flexible, have good adhesion and longer open times than normal polyolefins. APOs tend to have lower melt viscosity, better adhesion, longer open times and slow set times than comparable EVAs
  • Polyamides (PA), high-performance, for severe environments; high-temperature glues; typically applied at over 200 °C, but can degrade and char during processing. PA based hot melt has high service temperatures sometimes up to 150°C if there is no load to it. It is being applied widely for capacitors rigidizaiton. 

Typical Applications of Hot Melt Adhesives:

  • HEPA filters assembly.
  • Air & vacuum cleaners filter assembly.
  • Electronic components rigidisation.
  • Corrugated carton & packaging bonding
  • Furniture assembly
  • Art & craft

Part No

Base

Colour

Viscosity, cps

Softening Point 0C

Melt Point 0C

Open Time, seconds

Set Time, seconds

AE 121 EVA White 15'000 86 150 45 15-20
HMA 705 EVA White 4'500 80 160 30 15
HMA 8001 APAO White 5'500 - 7'000 110 170 80 3 - 4
HMA 8002 Polyester White 18'000 - 30'000 145 170 300 8
HMA 8003 APAO White 2'000 - 3'000 140 170 15 5
HMA 8003-PS    Amber Transparent 7'000 - 10'000 94 160 60 NA
HMA 8004 Metallocene Polyolefin White Transparent 700 -1'100 105  170 60 2
HMA 8005 APAO Slight Amber 2'500 140 170 70 20
HMA 8016 APAO White 3'500 - 5'000 115  170 10 - 20 3 -6
Pleated Paper Bonding

Polyurethane Reactive Adhesive

Polyurethane Reactive (PUR) hot melt has a combination of different positive attributes found in various, unique adhesives. PUR hot melt is not found in the normal form of a glue stick or bulk pellet, instead, it is melted from a solid prior to application and commonly dispensed from a 10oz tube similar to caulking adhesive or from a standard airtight 20 Kg drum.

PUR hot melt solidifies through moisture in the air to form a super strong bond that will not re-melt. There are both high and low-temperature PUR adhesives so the correct PUR applicator must be used. The reaction time is mostly between 24 to 72 hours. The reaction time must not be confused with the fast setting time with hot melts, in general, are known for. A PUR hot melt still can have a fast setting time from several seconds to minutes but it takes a longer time to set.

Because polyurethane is so strong and durable, it is ideal for a wide variety of applications. PUR is often used in woodworking and many other applications that would require a super stronghold with a very fast set time. PUR sets within five seconds, and will not re-melt which makes it great for the following applications.

Finish Carpentry, trim/crown molding, broken glassware, wooden frames, drawer assembly, shoe repair, carpet tack strips, laminate countertops, ceramic lawn ornaments, peeling wallpaper, chair/table repair, paneling, wainscoting, ceramic ceiling tiles, upholstery repair, flooring thresholds, arts & crafts, displays and signs, sports equipment, construction/remodeling, and plastic patio furniture repair.

Typical Applications of Polyurethane Adhesives:

  • Plastic parts bonding.
  • Filtration assembly.
  • Furniture edge bonding.
  • Electronic components bonding.
  • RFID tags bonding.

Part No

Base

Colour

Viscosity, cps

Softening Point 0C

Melt Point 0C

Open Time, minutes

Full Cure, Hours

PUR 3062 Polyurethane/Polyisocyantes White 3'000 72 140 4 - 7 4

Frequently Asked Questions

  1. Open Time is the timing required for the molten hot melt in liquid starts to solidify. Generally, it will take anything between 3 - 40 seconds and it is largely depending on the formulation of the hot melt adhesive.

  2. Setting Time is the timing required for the molten hot melt to set and hold the 2 mating parts together the moment it is contacted. 

  • Stick form
  • Granule shape
  • Pallet shape
  • Mini pillow shape
  • Block form

Yes. It is 100% thermoplastic and will not set and polymerise like thermoset type of adhesives. 

It ranges between 600C to 1400C depending on the base of the hot melt being selected. For EVA based hot melt, the highest temperature it can withstand is up to 700C whereas for Polyamide hot melt, it can heat up to 1400C.

Hot melt is made of thermoplastic and with the higher melting temperature, the viscosity will decrease drastically. The opposite will happen if the melting temperature is lower than recommended. 

Polyurethane hot melt usually does provide a stronger bond than a traditional hot melt. This is because the PUR hot melt forms a strong initial bond and then continues to strengthen as the adhesive reacts with moisture in the air. This is a chemical process known as cross-linking where the PUR hot melt attaches to the object being glued and itself to form a strong, permanent bond.

The answer is the air and the object being glued. There is plenty of moisture in the air to continue curing PUR hot melt; however, drier conditions may extend open times.

If unopened, the adhesive should be stored in a foil pouch in a cool, dry location. Do not expose the PUR tube to rain or moisture. Before shutting down for the day, extrude a one-inch bead of adhesive to ensure that air has been extracted from the tube. CAUTION: Do not touch the applicator heat cylinder or cartridge when at maximum temperature. Always wear gloves.

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