Low temperature hot melt adhesive bonds and seals delicate materials
In the packaging industry in particular, delicate materials such as paper, wrap around cases, carton and cardboard require bonding in a fast paced environment. Ideally, these applications use hot melt adhesives, however, the application process tends to involve high temperatures possibly damaging the delicate materials and resulting in high energy consumption. Fortunately, it is possible to opt for a low temperature hot melt adhesive which helps overcome those issues.
Low temperature hot melt adhesive, also known as cool melt, is usually based on synthetic resins. The systems exist as for instance EVA (ethylene vinyl acetate) copolymers, polyolefins and other polymers.
Benefits of cool melt adhesives in packaging
Low temperature hot melt adhesive gets its name from the fact that it allows application in lower temperatures than regular hot melts. Whereas a regular hot melt commonly requires at least 150°C, cool melt applications are possible from 90°C on. The low application temperature of these adhesives bring along several benefits.
- Increased machinery service life: as extremely high temperatures are not involved in the cool melt application process, the machinery is likely to deteriorate more slowly. This also reduces the need for frequent maintenance.
- Better operator safety: even though 90°C is still a high temperature, applying low temperature hot melts involves a much smaller risk for operators to get injured by burns. The low temperature also ensures that less odor is released during the application.
- Higher performance of packaging lines: low temperature hot melt glue is generally easy to apply and cures fast. This combined with the minimized maintenance intervals results in improved overall performance of the packaging line.
- Bonding and sealing delicate materials: the packaging industry involves many different types of materials that need bonding and sealing; some of these are temperature sensitive. In those cases, a low temperature hot melt adhesive can be used to make sure no harm is done to the delicate materials.
- Lower energy consumption: since the adhesive application does not require as high a temperature as regular hot melts, the energy consumption can be significantly reduced. This results in greater sustainability and contributes to reducing carbon footprint.
The cool melt adhesives additionally have other benefits which are dependent on the formula of a specific system. Such benefits common for low temperature hot melt glues include:
- Excellent adhesion
- Good hot tack
- Resistance to temperature extremes
- Fast curing
- No charring
- Good pot life stability
- Adhesion to porous surfaces
Low temperature hot melt glue improves cost efficiency
Usually the main reason for choosing for low temperature hot melt adhesives is their cost efficiency. Using these adhesives reduces costs in three ways:
- Energy consumption: as lower temperatures are required, the energy consumption decreases, which results in a smaller electricity bill.
- Operational costs: the absence of extremely high temperatures reduce the wear and tear of the machinery, which calls for less frequent maintenance reducing operational costs.
- Material costs: low temperature hot melt adhesive systems are generally cheaper to purchase than traditional hot melts. However, this should not be taken for granted: there are always exceptions.
Specifications of low temperature hot melt glues
Low temperature hot melt adhesives exist as different types: EVA hot melts, polyolefin based systems and many more formulations. These all have their specific uses. Some are designed for delicate surfaces such as paper, foam and fabric whereas others work well on cardboard and carton. The most common applications of low temperature hot melt glue in the packaging industry include gluing cartons and folding boxes as well as sealing and bonding wraparound cases, cardboard boxes and trays. For each application and material, it is crucial to consider the specifications of the adhesive.
Some of the most important specifications to look at are:
- Application temperature window: generally low temperature hot melt adhesive can be applied at temperatures between 90° and 140°C. Temperatures above 160°C should be avoided.
- Recommended application temperature: each adhesive system also has a recommended application temperature which is a smaller range than the temperature window. Usually the recommended application temperature lies between 90° and 130°C, but it varies per product.
- Softening point: the point where the hot melt adhesive starts to soften is usually greater than 60°C.
- Application method: Many cool melt adhesives are applicable using a roller or nozzle. These can be part of manual, semi-automatic or automatic application equipment depending on the product.
FDA approved cool melt adhesive for food packaging
When choosing an adhesive for packaging, it is also important to look at certification and standards. As low temperature hot melt adhesives are crucial for many packaging lines, and food packaging covers a great share of the industry, FDA approval is one of the most important certificates. Fortunately, many of these adhesives are FDA approved, meaning that they are safe to use on food packaging. To avoid any inconvenience, always check with the manufacturer to what extent the adhesive is food safe.
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