If you have ever made crafts or fixed broken items around the house, you know a hot glue gun is a helpful tool for quickly and easily bonding pieces together. Some of the most familiar, advanced and highest performing products you use every day, including disposable hygiene products, are also made using a similar hot glue method.
In manufacturing, the hot glue is called hot melt adhesive. The scientific term to describe hot melt adhesive is thermoplastic. This literally means “softer when heated,” and it is exactly what occurs. Hot melt adhesives melt into the surface of the layers or pieces they are applied to and form a grip as they cool down. They then harden and become solid again at room temperature.
Hot melt adhesives are able to repeat the heating and cooling process. This means you can separate two items that were bonded with a hot melt adhesive by reheating the hot melt to the temperature you used to apply it.
The equipment used for hot melts throughout the industry (and for disposable hygiene products in particular) is usually hotter and more complex than your at-home glue gun. This allows the hot melt adhesive to keep up with the speed of the production line. Unlike with a hot glue gun, hot melt adhesive is not simply applied as a thick bead. Instead, the equipment applies the hot melt adhesive in specific patterns in very precise parts of the diaper or pad. This creates a strong bond and helps with product performance.
An inside look at hot melt adhesives
Manufacturers use hot melt adhesives in diapers and feminine care products for many reasons. A key incentive is the fast action time that allows for high-speed production lines. Other benefits: they can adhere to a wide variety of materials, they hold up well against wetness and all the movement that a busy day brings, and they support product softness and flexibility.
Every hot melt has its own unique recipe for success, but the main components in this type of adhesive include:
- Polymers as a “backbone” for internal strength to hold things together and for good flexibility
- Resins to grip the layers it is holding together (adhesion)
- Plasticizers for flexibility and comfort
- Additives that give a longer shelf life but also provide special features such as color or UV resistance if and when needed
Where are hot melt adhesives used in disposable hygiene products?
Just like any recipe, the order and steps used to create the final adhesive are as important as the ingredients. Teams of scientists work together until each adhesive is just right and performs at its best for the role it plays:
- The basic construction of the diaper: it bonds the various layers together more efficiently
- Ensuring good core integrity: it helps with absorption, prevents the core from shifting and ensures that it does not fall apart when wet
- Elastic attachment: it holds elastics in place under stress from movement and weight
- Attaching the front and side tape: it will keep the diaper from falling off
- Positioning the feminine care product: it will make sure that the product holds to the underwear but is not too difficult to remove
- Wetness indicator: turns blue when it is time to change the product
As someone who finds using a hot glue gun helpful for at-home projects, you can now see why hot melt adhesives are very important in diapers and other disposable hygiene products.
Want to learn more? Read Things You Should Know About Baby Diapers and Adhesives.
Discover More about Substances of Interest