Polyurethane Foam Adhesives

What is Polyurethane Foam?

Polyurethane foam, or PU foam, is a synthetic polymer made from a reaction between polyols and isocyanates. It is an open-cell foam that is known for being flexible and lightweight while also being durable. Because of its porous nature, polyurethane foam is also a good thermal and acoustic insulator. It is commonly used in insulation, furniture, automotive interiors, and packaging.

Bonding Polyurethane Foam

Polyurethane foam bonding can be challenging. Its porous and compressible structure makes some adhesives ineffective and can lead to weak adhesion or bond failure. Some adhesives can also deform, melt, or dissolve the foam surface. This damage may occur from the temperature of the adhesive being too high or from harsh chemicals in the adhesive's makeup.

Because of these challenges, choosing the right adhesive for polyurethane foam is critical to ensure a durable and lasting bond. The adhesive must provide a strong initial tack without damaging or compromising the material. In many cases, you need an adhesive for foam specifically and to follow recommended surface preparation techniques. If you are bonding polyurethane foam to another substrate material, such as wood or plastic, you also need to ensure that the adhesive is compatible with both materials.

Every application is unique, and these adhesives are just a few suggestions you can explore. If you need help determining exactly which adhesive to use, we can provide you with a personalized product recommendation.

Types of Glue for Polyurethane Foam

Selecting the right adhesive for polyurethane foam depends on the environmental conditions and intended application. Different adhesives offer different bonding capabilities and properties.

Some commonly used adhesives for polyurethane foam include:

• Spray Adhesives - Spray adhesives are one of the most common glues for polyurethane foam. They are easy to apply and can provide even coverage over large surfaces.

• Hot Melt Adhesives - Hot melt adhesives, including sprayable hot melts, provide strong initial tack and adjustable open times. They can be an excellent choice for production lines where speed and repeatability are critical.

• Solvent-Based Adhesives - Solvent-based options can create long-lasting bonds, but you need one that is designed for foam or it could damage the material. These adhesives also require proper ventilation and careful handling due to solvent fumes.

• Contact Adhesives - Contact adhesives provide instant adhesion once both surfaces are coated and pressed together. They are well-suited for applications that require immediate handling after bonding.

• Two-Part Structural Adhesives - For structural bonding applications with another type of material, an epoxy or other type of structural adhesive may be a good option. Be sure the adhesive is compatible with polyurethane foam, or you could damage the foam.

While types of adhesives have similar properties, bonding capabilities still vary between products. Always check the technical datasheet (TDS) for specifics on properties, curing time, and recommended substrates. You can also consult one of our experts.

How to Bond Polyurethane Foam

Bonding polyurethane foam can be challenging because of its porous structure and delicate surface that can be damaged by some adhesives. Consequently, not only is it imperative to use the right polyurethane foam glue but also to do the right surface preparation.

While surface preparation and application can change depending on the specific  product, the following steps are generally recommended:

1. Clean and dry the surface. Especially because open-cell foams can trap debris, it is important to clean the surface to remove dust, oil, and other contaminants that can interfere with adhesion. Do not use a harsh solvent that will damage the PU foam.

2. Abrade the surface. If you are bonding polyurethane foam to another substrate material, slightly abrading the surface and cleaning it to remove the loos debris is often recommended.

3. Apply the adhesive evenly. An even layer of adhesive can lead to better long-term results. Spray adhesives make even application easy.

4. Allow the adhesive to cure. Adhesives have different cure times. Follow the manufacturer's recommendations to allow enough time for the adhesive to fully set before stressing the bond. Rushing this step can result in weak adhesion or partial bonding.

Before committing an adhesive to a full run of products, you should test it first to verify it does not damage the polyurethane foam and is compatible with your application. Failure to do so could lead to wasted material and potential rework.

Let Us Help

Every project is unique, and even subtle differences in environmental conditions or bonding requirements can impact which polyurethane foam adhesive you should choose. Whether you are bonding polyurethane foam to polyurethane foam or another substrate material, we can help you determine the best product for your needs with a personalized product recommendation.