If you have been assigned the task of purchasing an industrial hot melt glue for the first time Hot Melt or if you are experiencing difficulties in application, it is critical to understand how these adhesives work in order to avoid the most common problems and get the maximum performance from the adhesive.
In this article, we will examine in detail what Hot Melt glues are, how they operate, how to apply them, and provide valuable tips for maintenance and application.
Definition of Industrial Hot Melt Glue
Industrial hot melt glue, also known as “Hot Melt,” is a completely solid thermoplastic material that is applied in a molten state and, upon cooling, creates a solid bond. Most hot-melt adhesives lose their tack once they solidify; those that retain their tack are commonly referred to as pressure-sensitive adhesives.
Hot Melt glues are generally formulated using polymers to impart strength and flexibility, resins to provide initial adhesion, and plasticizers to adjust viscosity and ease of application. These formulations may also include waxes for diluting the adhesive and antioxidants to preserve the adhesive in high temperature conditions during the storage period.
Operation of Hot Glue
As previously mentioned, Hot Melt glue is applied in a liquid (molten) state after being heated to the specific application temperature of the adhesive. Making sure the glue is hot enough is essential to ensure proper “wetting” of the first substrate, allowing the glue to fill the small cracks on its surface. During the “open time” period of the adhesive, when the glue is still hot enough to ensure adequate wetting, it is critical that the second substrate be brought into contact with the first. At this stage, compression is crucial, as it helps ensure a firm bond between the two surfaces.
Hot Melt Glue Application Procedure
The initial stage of the application process involves loading the adhesive into a dedicated hot glue tank. Next, the molten adhesive is transported via a hose to the applicator, from which it can be sprayed, extruded, laminated, or coated onto the substrate, depending on the specific needs of the application.
Spraying
This method is useful for covering larger areas, for high-speed production lines, and for heat-sensitive substrates.
Extrusion
The use of nozzles that distribute adhesive in the form of beads or lines is ideal for closure systems where a precise application position is required.
Roller coating
This is a quick, efficient and uniform way to apply adhesive to flat surfaces of substrates such as paper, wood, metal or plastic.
Die-cut coating
This method offers a high degree of uniformity in adhesive distribution, with the adhesive extruded from a slot in the die head directly onto the substrate.
Maintenance of Hotmelt Glue
The application of hotmelt glue Hotmelt with the appropriate temperature, pressure, amount, and level of compression is essential to ensure effective adhesive bonding. The following are guidelines that can help solve the most common problems encountered when using hot glue.
Hot Glue Tank
Be sure to apply the adhesive at the correct temperature to avoid oxidation and over-burning if the temperature is too high, or strung adhesive and ineffective application if the temperature is too low.
Applicator
The correct application temperature is crucial to prevent over-application of adhesive, which can occur if the glue is too hot, or poor and uneven application if the temperature is too low.
Pressure
Adequate pump pressure is essential to avoid restricted adhesive flow or the risk of clogging the applicator nozzles. Excessively high pressure can cause splashing, over-burning, and excessive adhesive consumption, compromising the efficiency of the process and posing a hazard.
Substrate Materials
Substrate temperatures between 15°C (60°F) and 35°C (95°F) generally produce the best results. When a hot glue comes into contact with a cold surface, its temperature drops rapidly, leading to poor adhesion and wetting problems that can cause faulty adhesion.
Hot Melt Glue Application Tips.
Here are some tips that come from decades of experience in Hot Melt solutions.
Compression
The correct amount of compression is essential to prevent defective adhesion or long-term compromise of integrity. Too little compression can result in spontaneous failure of adhesion, while too much compression can deform substrates, compromising adhesion.
Wetting
Adequate compression at a sufficiently high temperature should allow proper wetting of difficult surfaces, such as coated packaging materials with low surface energy.
Opening Time
The opening time of hot melt glues should be aligned with the application time. Too short an opening time may prevent proper wetting of surfaces, while too long an opening time may cause problems during compression.
Amount of Adhesive
It is important to apply the optimal amount of hot glue to ensure proper adhesion. Excessive adhesive can lead to problems with open time, excessive consumption, stringing, and spillage during compression, resulting in the need for cleaning and contamination of machinery. Conversely, an insufficient amount of adhesive will reduce open time and setting speed, adversely affecting gap-filling properties and adhesion formation.
By carefully following these guidelines and considering the key aspects of hot melt glue application and maintenance, you will be able to achieve optimal results and maximize the effectiveness of this important thermoplastic adhesive.
