Initially, Hot Melt Adhesives (HMAs) were primarily developed for industrial use. They have been, and are now, widely used in many application markets such as packaging, bookbinding, woodworking, electronics, lamination, shoemaking, craft gluing, hobby work, cabinet making, florist work, upholstery, product assembly, and many other applications. HMAs have also been promoted to home and shop use by providing hot melt glue sticks accompanied by simple and lightweight glue guns.
Several different types of hot glue sticks are available in the market. Here are answers to common hot melt stick questions:
1. What colors do hot glue sticks come in?
Water white to dark amber; clear to opaque glue sticks are all available. Normally, the raw material cost of light color and clear glue sticks are more expensive. Some of these look nice aesthetically but often offer insufficient adhesion performance when compared to dark adhesives due to their relatively low surface energy.
Any customer required colors are possible upon specific request. Color is sometimes needed for craft, hobby, and certain artworks. Coloring agents can be organic dyes and inorganic pigments.
2. What sizes do hot glue stick come in?
Various diameters and lengths are readily available in the glue stick market – such as: 1/4″ dia. (diameter) mini x 4″ long, 7/16″ dia. x 4″ long, 7/16” dia. x 10″ long, 5/8″ dia. x 2″ long, 5/8″ dia. x 10″ long, 1″ dia. x 3″ long, 1-3/4″ dia. x 1-3/4″ long plugs. Technically, glue stick manufacturers are able to provide any diameter and length according to the selected glue guns and specific market needs. Among the above diameters, 7/16” (about 11.2 mm) diameter. is the most commonly used size in this market. The consistency of the diameter plays the most important role for glue gun application. How to produce a consistent diameter of glue stick will be discussed in a separate article.
3. What are hot glue sticks made out of?
Three thermoplastic elastomers are commonly used for making glue sticks: EVA (Ethylene Vinyl Acetate), APAO (Amorphous Poly Alpha Olefin), and PA (Poly Amides). Various tackifiers are also incorporated in these hot melt glue sticks. They are basically categorized as natural resin- such as rosin and Terpene derivatives, and synthetic petroleum hydrocarbon resins- such as aliphatic, aromatic and di-cyclo-pentadiene. PA glue stick is a 100% synthetic polymer without modifying any tackifying resins.
4. Basic Properties of hot glue sticks
Ring and Ball Softening Point, and melt viscosity are two major physical properties shown on most technical data sheet (TDS).
5. How are hot glue sticks processed?
Open time, set time, and hot tack of HMAs are very important properties that will greatly affect the degree of bonding. Since these performances are greatly affected by the applicators, application conditions or environment, and substrates; most data reported on TDS are very subjective and are used for reference only.
6. How do hot glue sticks perform?
Adhesion performance to various substrates is also very subjective and is greatly dependent upon the cohesive strength and surface energy of bonded substrates. A real-world trial is always required before one can select an appropriate glue stick. Normally, the rosin derivative incorporated HMAs can offer better adhesion to low surface energy materials. However, the color of these HMAs is normally darker than their counterparts. Application at a higher temperature, e.g. 190C (374F), is also very helpful for bonding onto low surface energy plastic substrates. Because the elevated temperature can melt the surface of plastics and induce more contact surface.
For more information call or email Pierce Covert,
Glue Machinery Corporation