When you need cushioning, you choose foam. The compressible yet resilient bubbles trapped in elastic material absorb shocks and vibration, giving it thousands of uses from packaging to upholstery. Foam comes in a wide range of materials and ranges from firm and heavy to soft and light. There's a foam to suit every application, but it does have limitations: it can be difficult to fit or install, and it may not have the desired final appearance or surface properties.
The way around these problems is to specify a pressure sensitive adhesive (PSA) lamination for your foam fabrication.
Overview of PSA foam lamination:
"Lamination" refers to adding one or more layers to a sheet or roll of foam. There are two reasons you might do this:
- To create a composite of two or more materials, combining the properties of foam with a second material.
- To make it easier to attach foam to a surface or to other foam pieces.
In both cases the start point is to add an adhesive layer to the surface of the foam. This is harder than it sounds, thanks to foam's cellular structure.
Foam is produced by forming bubbles in a rubber-like material while it's still liquid. The details vary depending on type of material and manufacturer, but in essence it involves creating a gas during the chemical foaming reaction. By incorporating various additives, and with precise control of the process, manufacturers are able to control both the size and size distribution of these bubbles, and so the density of the foam. This creates a cellular structure that's the key to foam's flexibility and versatility.
These cells may be either open to one another, in which case the foam is porous, or completely closed. A closed cell foam resists water and tends to be firmer than an open-cell material, but takes longer to spring back after compression.
The material has a part to play too. Many different ones are used, but all need elastomeric properties. In other words, they must have some elasticity. Polyurethane, polyethylene, EDPM and silicone are just a few of the materials that make excellent foams. In each case they combine the properties of the base material with the characteristics of the foam.
However, this same cellular structure can make foam difficult to use. Inherently porous, if a liquid adhesive is applied it tends to run in to the structure rather than resting on the surface. Naturally, this makes it difficult to bond anything to the surface of the foam.
What is a PSA?
Adhesives take many forms, some of which rely on a chemical reaction to create a bond. A PSA is formulated from polymers that naturally create bonds to other materials. These bonds are strengthened by applying pressure, which encourages more "wetting" of the substrate, and so greater adhesion, (hence the "pressure" part.)
Adhesive producers are able to control the tack, peel and shear properties to suit the application. Together these determine if an adhesive will lift away easily, (like a "Post-It" note,) grab and bond tightly immediately, or build strength over time. Two other properties of concern in many applications are the ability to resist water and UV light (as in sunlight.)
At Merryweather we typically have 40 different adhesives in-stock to suit a wide range of application needs. If necessary we can obtain other PSA's at short notice, including those which are UL approved.
At Merryweather foam is laminated with PSA in a continuous process. Starting with a roll of foam, the material is drawn between two rollers. Separately, PSA, also in roll form, is fed into a bonding roller. This presses it against the foam, using heat and pressure to create a bond.
PSA is usually supplied with some form of release coating on one side. This stops it from sticking to itself. The coating can either be left in place or removed. The reason for removal is to allow a second material to be bonded to the foam. This might be a woven or nonwoven textile, a thermoplastic film, or foam of a different material and/or density.
For some applications foam receives a layer of PSA on both sides. An example would be to create foam-backed textile pieces that can be fixed to walls or other surfaces, perhaps for display materials or as sound deadening.
Merryweather can supply PSA laminated foam in slit-to-width roll form, in individual sheets or as die-cut finished shapes. When die-cutting it's possible to perform a "kiss-cut" that doesn't go completely through. This simplifies transportation and storage by keeping the pieces together until they can be separated at the point of use.
Benefits and Applications
PSA lamination makes foam easier to use. It simplifies the assembly of any complex flexible foam fabrication, it makes it easier to mount foam shapes on almost any surface, and it enables the creation of composites that combine the characteristics of different materials.
For packaging materials, PSA lamination enables foam pieces to be joined to create complex shapes needed for effective cushioning of delicate or high-value items. For upholstery cushioning, bonding a textile to the foam can simplify assembly. Double-sided lamination can make it easier to mount foam-based material to a substrate, which may be desirable for sound deadening and display materials.
Discussing PSA Lamination with Merryweather
Foam is versatile but may not have the appearance or functionality that you need. Laminating allows a second material to be bonded to the surface, overcoming this weakness. Alternatively, laminate with just a PSA for improved ease of installation. It's possible you've never considered how PSA laminated foam can simplify your use of foam fabrications. If this is the case, a conversation with our specialists could lead to ideas that save you money and improve your products.