The Making of Hot Melt Adhesives- DIY
A hot melt adhesive or “hot glue” has many advantages around the house for DIY projects or commercial or industrial uses. Hot melt adhesives can take you from building craft or hobby projects, like bird houses or model airplanes or boats; to outdoor projects where quick fixes may be needed; or complex assembly of electrical equipment. It’s a quick and portable tool that can be used all over the home or in work places.
A big advantage of hot melt adhesives is its low cost. For the same amount of money, you can purchase either one tube of cold adhesive or you can purchase a kit for using hot glue. More often than not, the hot glue will have more usage out of it for the same amount of money you would spend for a cold adhesive. And the refills for the hot melt adhesive will be very cheap for one refill compared to purchasing another bottle of cold adhesive. Also, you do not have to be concerned about it drying out. Cold adhesive must be kept tightly closed and may have to remain in a certain position to keep it from spilling out of the container. Having it not stored properly can lead to it drying out and it not being able to be used.
The making of hot melt adhesives is a delicate process. Using the proper materials from start to finish will insure the end product’s best use by the consumer. A glue manufacturer will start with base materials such as:
- Ethylene-vinyl acetates (EVA)- Used to absorb physical shock, used in shoes and other athletic materials; in this case, it can provide strength.
- Polyolefins- Used to insulate electrical wires, a common component to heat shrink film and is also used in wetsuit construction; in this case, it can be used to provide water resistance
- Polyamides- Known for their flexibility and strength, it can work with an EVA to provide added strength to a glue
- · Polyurethanes- Used in fabrics like Spandex®, they are mostly used in high performance adhesives
- Styrene block copolymeres- A thermoplastic elastomer; used is electronic devices like computers, cell phones, or televisions.
These compounds, when melted, have a smooth consistency without the temperate of the glue being too hot, which can melt an object it is being used on. This is one of the first things a company looks at when making a hot glue product. Another aspect to look at will be the crystallization, or hardening, rate of the glue. The composition is usually formulated to have glass transition temperature (onset of brittleness) below the lowest service temperature and a suitably high melt temperature--- the faster the glue hardens, the stronger the glue will be.
The second part of the mixture will be additives that can be blended with the base material. These normally include waxes, UV stablilizers, pigments and or dyes, tackifying resins, plasticizers, glitter, flame-retardants, antioxidants, biocides, and anti-static agents. Fillers are also added to the product to aid in the goals of reducing costs and improving the strength of cohesion. Some examples are calcium carbonate(aids with keeping glue from sticking to other objects after it has hardened), talc, carbon black (helps move heat from the glue), barium sulphate (a white pigment), and kaolin clay.
An advantage of hot melt adhesives is that they do not produce noxious fumes and are less harmful to the skin, if it comes into contact. Many people worry about how adhesives like Super Glue will affect their health. Cyanoacrylate, the active ingredient in Super Glue is very hazardous to people. After exposure, many people can get dizzy, or experience nausea or vomiting when exposed to the fumes from Cyanoacrylate.
From the above information, one can see that there are many different combinations a manufacturer can use in making a hot adhesive and its basic usage and benefits. Manufacturers will mix any of the above components, or others if they so choose, to make the perfect hot glue for the desired need of a consumer, like basic crafts or complex electronic assembly. If you are in need of a specific type of glue, contact the manufacturer to see if they have a product to fit your needs. Many independent makers can even make special order glues for your needs, whatever they may be.