Manufacturing process

Sintered porous plastics are created using a combination of heat and pressure to bond the materials together. The objective is not to melt or change the main properties of the material, but to create a porous material suitable for the particular use.

Material options

Sintered porous plastics can be manufactured from a variety of materials. The selection of the material is based on the needs of the end product, and is a key part of the initial design and engineering process. Here are the four main materials and some of their traits:
Polyethylene (PE)
This is the most commonly used material with a large pore size range and used in higher end processing.  Sintered PE is a diverse application.

Polypropylene (PP)
For strong applications where rigid structure and a large pore size is important, check and see whether sintered PP serves the right purpose.

Polytetrafluoroethylene (PTFE)
For applications in need of high temperature tolerances or high chemical resistance, the moldable material of sintered PTFE is perfect.

Polyvinyllidene Flouride (PVDF)
For applications where your device is subject to oxidizing agents or solvents, sintered PVDF is perfect.

While these are the more common materials used to design sintered porous plastics, 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 sintered porous plastic component, it’s critical to understand three key physical properties desired as they impact the materials and functionality of the part:

Understanding typical material properties will guide you in selecting the right polymer for your device’s function and operating conditions.  The above characteristics can be highlighted or downplayed based on your specific product needs.  Below is a chart that shows the common materials with their physical properties; however, this is not an exhaustive list. 

• Pore size: Pore size defines the size of the voids in the porous media.  Depending on the material and the amount of processing, pore size can range from very small to handle gases – to larger pores that can manage liquid materials. The pore size impacts wicking speed, wicking distance, filtration efficiency, and flow resistance.
• Pore volume: Pore volume defines the percentage of air in the sintered plastic part compared with the total volume of the part. Flow state depends on how your liquid or gas can pass through your chosen materials. Sintered particle plastics can create large or small spaces that hold the perfect amount of liquid. The pore volume impacts the absorption volume and flow resistance of your part.
• Operating temperature: Operating temperature defines the temperature range at which the final sintered plastic part will be required to operate.

Chemical properties

Choosing the right polymer material is important to ensure lasting functionality for your end product or device.  One of the key questions to consider is with what – if any – chemicals the sintered plastic component will come into contact. There are many types of porous polymers available to suit almost any operating environment or condition. 

Below is a table that shows chemical compatibility of the common polymers:

Additive options

Additives and treatments open the door to many possibilities for your sintered plastic component. Below are some additives and treatments used with the common polymers listed above:   

Polyethylene (PE) and Polypropylene (PP) accept these options:

• Self-sealing, liquid barrier
• Hydrophilic treatments
• Colorants
• Color change
• Ion exchange
• Bactericidal / bacterial static
• Carbon, potable water, odor elimination

PTFE accepts these options:

• Oleophobic treatment
• Polypropylene scrim support

Geometric options

One of the key benefits of sintered porous plastics is their ability to be designed and manufactured to accommodate many geometric options – from sheets to complex 3D shapes. There are very few limitations in what size or shape the sintered porous plastics can take.  As you think about incorporating this material into your manufacturing process, consider these geometric options:

• Standard sheets or rolls
• Rods
• Tubes
• Nibs (for writing instruments)
• 2D plugs
• Simple and complex 3D shapes

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

Assembly & converting options

Customizable assembly and converting options are endless. Typical options for sintered plastics include:

• Thermal & ultrasonic welding
• Overmolding
• Die-cutting
• Press fit
• Pressure-sensitive adhesive (PSA)

It’s important to understand how the final product or device will be assembled when talking with our engineers, as sintered plastics can be used to decrease number of assembly steps by combining multiple parts into one custom-engineered part. 

How to use sintered porous plastics

• Filter – In the fields of healthcare, filtration properties are extremely important.  Cross-contamination issues are addressed through several types of filtration, absorption, and ventilation options.  Choosing a pore size that offers the most protection is key. One example is filters in nasal inhalers and spray pumps, where filters are designed to be hygienic and deliver the correct amount of medication. 
  
• Apply – For precise application, our pure reservoirs and beauty applicators are designed with perfection in mind. Our applicators and blenders create uniform flow, consistent feel, and a quality product that performs and feels flawless. 
  
• Vent – Sensitive electronics needs components that keep out dust and dirt.  Our materials can be used as EV and fuel cell vents, separators, and isolator electrolyte holding media.    
  
• Diffuse – Diffusion and distribution properties are prevalent in our media for 3D printers.  This newer technology requires precision in wicks, filters, vents, and absorption media to create a flawless end product.

• Wick – The home air freshener needs to be long lasting and consistent, delivering fragrance through porous sintered particle wicks that use capillary action customized for the formula that is being delivered.

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.