Adhesives for Polypropylene Foam

What Is Polypropylene Foam?

Polypropylene foam, sometimes referred to as PP foam, is a type of closed-cell foam made from a polymerization process involving propylene monomers. It is well known for its low density and compression properties that give it a great strength-to-weight ratio. Polypropylene foam also has a high resistance to chemicals and moisture, so it is a versatile material.

Common applications for polypropylene foam include:

• Packaging
• Automotive interiors
• Building insulation
• Marine components
• Furniture
• Sporting goods

Bonding Polypropylene Foam

Although polypropylene foam is widely used across many industries, achieving a strong adhesive bond with it can be challenging. The material's structure and properties make it difficult for many adhesives to achieve reliable and lasting adhesion.

One of the biggest problems with gluing polypropylene foam is the material's low surface energy. Similar to its hard plastic form, the foam has a low surface energy that inhibits wetting and adhesion for many traditional adhesives. Consequently, the adhesive must be compatible with low surface energy substrates to form lasting bonds.

Another problem with gluing PP foam is its closed-cell structure. Compared to open-cell foams, closed-cell foams can limit the adhesive's penetration of the surface and mechanical interlocking. As a result, the adhesive struggles to reach its optimum bond strength.

Finally, foams can be sensitive substrates already, but polypropylene foam has a lower thermal resistance than many other foams. High-temperature adhesives may damage the foam by melting or collapsing it. Harsh solvents in the adhesive can also damage the surface of the foam.

Because of these hurdles, many adhesives are not compatible with polypropylene foam. Adhesive selection and proper surface preparation are critical to not only getting a strong bond, but also to avoiding substrate damage.

While these products are some reliable options for adhesives for PP foam, even the smallest change in the application can impact which adhesive is best for your needs. If you need help determining which polypropylene foam to use, you can get a personalized product recommendation from one of our experts.

Types of Glue for Polypropylene Foam Bonding

Different applications and bonding requirements call for different adhesive chemistries. Selecting the right adhesive improves bond strength and reliability. Some adhesives for polypropylene foam include:

• Hot Melt Adhesives- Hot melts are a good option because of their great strength and fast set times. They are also easy to automate.

• Spray Adhesives- A popular option for foams, spray adhesives are great for even coverage and sensitive substrates.

• Contact Adhesives- These adhesives provide fast tack and instant bonding when pressed together.

• Cyanoacrylate Adhesives- For repairs or small fixturing, cyanoacrylates are a fast-setting solution.

• Structural adhesives- If you are looking for a glue for PP foam and another material like wood, metal, or plastic, a structural adhesive may be a good choice. The adhesive needs to be compatible with both substrates and may require more surface preparation.

Each of these adhesives has its strengths and weaknesses, so it is important to choose the right one for your needs. Before selecting a PP foam adhesive, you should consider the bonding environment, production process, substrates, and more.

How to Bond Polypropylene Foam

Successful bonding isn't just about the right adhesive; it is also about the right surface preparation. Every adhesive is different, so follow the guidelines outlined by the manufacturer. In general, surface preparation will include the actions below.

• Clean and degrease the foam surface to remove any contaminants that could interfere with adhesion. Avoid harsh solvents that could damage the foam.

• If you are working with another material, you may need to abrade the surface or pretreat it (plasma, corona, or flame treatment). Make sure to clean the surface after abrasion to remove loose particles.

• Apply a primer or promoter if recommended.

• Apply the adhesive evenly for best results.

• Follow the manufacturer's guidelines to allow the adhesive to set before handling.

Because polypropylene foam is challenging to bond, always test the adhesive under your specific condition requirements before full-scale use.

Get a Product Recommendation

Polypropylene foam can be a challenge to glue, but the right adhesive and the right surface treatment can make all the difference. If you're unsure which adhesive fits your application the best, we want to help. Our team of application specialists can provide a personalized recommendation for an adhesive for polypropylene foam. Just reach out.