Porous Foam

Biocompatible, hydrophilic and hypoallergenic open-cell foam that can be customized with color, antimicrobial, and other additive options

Porous foam innovation expert

Porous foam is created using proprietary or customized blends of raw materials through a clean polyurethane process without the use of catalysts. Different formulations offer wide-ranging densities, porosities, and levels of softness to meet specific customer requirements. Open-cell foam types include both medical-grade (ISO 10993-certified) and cosmetic foams, with pore sizes ranging from 90 microns to over 350 microns. Porex has the ability to incorporate customer-exclusive additives including antimicrobials, nanomaterials, pharmaceuticals, botanicals, cosmetic ingredients, and colorants into the foam. Converting, roll stock, and laminations are also available.

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Redefining the Capabilities of Foam with Open-Cell Technology

Manufacturing Process

Open-cell foam can be manufactured using two different processes – a conventional “one-shot” process and a two-step prepolymer process. While foam made with the “one-shot” process is used in furniture and car seat cushions, foam made with the two-step prepolymer process is used in unique applications such as advanced wound care, patient positioning, and cosmetics.  Porex manufactures open-cell foam using a unique two-step process that results in an intricate network of omni-directional pores created by CO2 gas that is released during the reaction. 

Porous Foam

Material options

Porous foam uses a mix of materials that are thoroughly evaluated based on product needs. Here are the most common materials and their traits:

Toluene diisocyanates (TDI)
The most commonly used isocyanate which is highly volatile with an aromatic structure.  Used when a tighter environmental, safety and health regulations are required

Methylene diphenyl diisocyanates (MDI)
Used when a more environmentally friendly solution is wanted as it is less volatile and has an aromatic structure.

Hexamethylene diisocyanate (HDI)
While more expensive than the other materials, it produces a desirable non-yellowing foam with an aliphatic structure

While these are the most common materials used to design porous foam components, there are many more that are possible and can be used based on your end product’s needs.  Work closely with your application engineer to define your specifications, and they can help select the best material(s). 

Physical properties

When designing a porous foam component, it’s critical to understand what physical properties you may need as they impact the materials and functionality of the part:

  • Pore size: Pore size defines the size of the pores in the porous media.  Depending on the material, pore size can be large or small.  Pore size directly relates to the absorption rate, absorbent / retention capacity, dimensional expansion when wet, and the air flow of the porous foam.

  • Absorption: Average mass of the test solution that is retained per 100 cm2 or per gram of sample.

  • Fluid retention: Amount of test solution retained in the sample when a 40mmHg compression load is applied over the entire sample area.

Understanding typical material properties will guide you in selecting the right porous foam for your device’s function and operating conditions.  Below is a chart that shows the physical properties to consider when designing your end product, along with the range of options most commonly requested. However, if you don’t see an option listed below, please still contact us to discuss your specific needs, as we can assist you in choosing the right porous foam.  

Physical PropertiesRange
Absorption14 – 18 g/g (70 – 90 g/100cm2)
Fluid Retention8 – 11 g/g (40 -60 g/100cm2)
Aesthetic OptionsVarious softness levels, tacky / non tacky, different options for each side
Carrier paperYes or No
Dimensions1.25 mm – 6.35mm (poured to thickness)
2mm – 30 mm (skived to thickness)
38cm – 55 cm width
Customization optionsWidth, thicknesses, pressure-sensitive adhesives, MVTR film lamination, die cutting, addition of customer supplied active ingredients

Additive options

Porous foam can be manufactured with a variety of additives and treatments that open the door to many design possibilities for use in your end product. Below are some additives and treatments that can be used with the two-step prepolymer process described above:   

  • Hydrophobic Treatments
  • Hydrophilic treatments
  • Colorants
  • Color change
  • Bactericidal / bacterial static
  • Carbon, potable water, odor elimination

Geometric options

Porous foam can be manufactured into a variety of shapes and sizes. As you think about incorporating this material into your manufacturing process, consider these options:

  • Sheets
  • Rolls
  • 2D plugs
  • 3D simple and complex shapes

Our engineers can also look at your manufacturing process and determine which size, shape and dimensions you need.

Assembly & converting options

Many customizable assembly and converting options are possible. Porous foam can be manipulated into many shapes and sizes via:

  • Die cutting
  • Skiving
  • Splitting
  • Lamination (thermal & PSA)

Whether you need bulk or individual packaging, our engineers can help design a porous foam product perfect for your ideas. 

How to use porous foam

  • AbsorbAbsorption of moisture and shock, softness, and added antimicrobial properties make foam perfect for patient positioning and surgical support applications.

  • AbsorbHeat and moisture exchangers take advantage of the absorption properties. Because it is biocompatible and hypoallergenic makes it a good candidate for skin contact applications such as PPE face masks.

  • Apply – Application ease allows delivery of the precise amount of liquid in topical skin adhesives. There is no worry about skin contact for medical and cosmetic purposes.

  • ApplyCosmetic applicators can be customized into hard or soft materials. The hypoallergic properties allow for use with liquid, cream, and powder-based foundations.  Wedges and blenders are precise and can be created in a variety of shapes and sizes.

  • Filter – Filtration properties allow for therapeutic techniques such as using a suction dressing to remove excess exudation while treating acute or chronic wounds and highly sensitive second- and third-degree burns.  Foam allows the wound edges to be drawn together, reducing the chance of edema and infections. Adding a carbon additive helps with odor. 

This list of application examples are just a small selection of what is possible. Check out our market pages to see more examples of our porous polymers in action.