QPAC® Poly(alkylene Carbonate) and Glass Sealing Paste

In this interview, AZoM talks to Peter Ferraro, Director of Business Development at Empower about the benefits of QPAC® Poly(alkylene Carbonate) Copolymer Binders for Glass Sealing Paste Applications.

Empower Materials is at the forefront of the development of cleaner, more environmentally friendly binders. Can you tell us more about the QPAC^® range and the main benefits of CO2 based polymers for binding and sealing applications?

Empower Materials manufactures a family of Polyalkylene carbonates. Our main product is QPAC^® 40 Polypropylene Carbonate.  This material is manufactured with a range of molecular weights ranging from as low as 50,000 to 350,000 +. Our new catalyst technology developed over the last several years has allowed us to make higher molecular weight QPAC^® 40 which has opened up new binder opportunities.

We also make QPAC^® 25 Polyethylene Carbonate with a molecular weight range from 100,000 to 230,000+.  Again our new catalyst technology has allowed us to make this product with a higher molecular weight. We are also able for the first time to commercially offer both QPAC®100 Polypropylene/Polycyclohexene Carbonate and QPAC® 130 Polycyclohexene Carbonate.  

The main benefits of this family of polymers is the ability to completely decompose the binders at low temperatures, lower than most any other binder in the marketplace in not only air but in non-oxidizing environments. Additionally, after debind there is very little residual contaminants remaining after the binder is decomposed.  

These two qualities are highly important to our customers who are working with sensitive materials in high tech applications. At the same time, the adhesion and green strength of the polyalkylene carbonates are excellent. Therefore mechanical and sealing properties can be improved along with the benefits of an improved binder decomposition process.

What makes the QPAC Poly(Alkylene Carbonate) systems greener?

QPAC^® Polyalkylene Carbonates are synthesized from carbon dioxide and require approximately 50% less petrochemicals than traditional petroleum based polymers. They also exhibit some biodegradable properties. Both of these features make QPAC^® a green material,

QPAC^® Poly(Alkylene Carbonate) copolymer binding systems are used for a number of different applications. Can you tell us a little bit more about the vast range of industries that use the empower range?

Yes, QPAC^® Polyalkylene Carbonates binders / sacrificial materials are used in a wide range of industries. This includes binder applications in dielectric tapes and pressed parts in passive electronic components, conductive pastes for electronic, solar and other applications, brazing binder in flux pastes, and as sacrificial channel formers for MEMS and other electronic components.  One of the most promising areas of growth using the binder is in glass systems such as thick films, sealing pastes and glass preforms. Applications include glass packaging, displays, LEDs, OLEDs and hermetic glass gaskets.

Glass sealing pastes require some specific properties, how does the Empower QPAC Poly(Alkylene Carbonate) copolymer binding systems meet these requirements?

As in the name, glass sealing pastes need to create a good seal.  Therefore the paste should be dense with few voids and have good adhesion. Additionally, any contamination in the seal after the glass is sintered will negatively affect the seal and create the opportunity for leaks. The decomposition properties of QPAC® 40 Polypropylene Carbonate results in a higher density seal with few voids. The binder also has very high adhesion properties with glass frit.   

Glass sealing pastes also require unique rheology. QPAC® 40 Polypropylene Carbonate is shear thinning which is important feature for dispensing/ printing glass pastes. Additionally, the polymer can be modified to offer a range of viscosities.

In particular, the system offers complete decomposition at low temperatures, why is this so important?

Many glass sealing applications require a low temperature melt glass powder or frit. Advancements are continually being made to lower the melt temperature of the glass by the glass frit manufacturers. A lower binder decomposition temperature is required for these types of glass powders. The binder must be decomposed before the glass starts to melt. Otherwise the binder and its gases will get trapped within the glass structure. This will result in voids, and hence lower density.

QPAC®40 Polypropylene Carbonate can be fully decomposed before the glass melts. This has been proven in several glass sealing paste applications where other binders could not work because of their high decomposition temperature.

Image 1. Thermal decomposition of QPAC® 40 PPC, versus ethyl cellulose and acrylic binders used in glass pastes.  Decomposition is in air and ramping at 2 ^oC/minute

Leaving behind low residuals and ash content after decomposition are also benefits, how does the QPAC solution ensure minimal residuals?

PF. Trapped contaminants such as ash and carbon that are left behind after the binder decomposes also creates problems with sealing of the substrates. A compromised seal caused by contaminants will negatively affect the reliability of the final product. Since QPAC® does not leave behind carbon or other contaminants, this eliminates the problem of having particulates left behind to adversely affect the seal.

Other binders such as ethyl cellulose inherently contain higher amounts of ash and carbon. These levels of contaminants are further amplified because the glass melts before the binder can fully decompose.

Image 2. Appearance of thermal treated thick film pastes. This shows the higher density and visually cleaner part using QPAC® 40 as the binder with glass frit as compared to acrylic and ethyl cellulose binders.

QPAC system offers a more environmentally friendly manufacturing environment.Can you tell us a little bit more about how this can benefit your customers?

QPAC Polyalkylene Carbonates decompose to water and carbon dioxide. Therefore venting of toxic byproducts from the decomposition process is not needed. Other binders result in harmful fumes and soot that cause environmental and equipment issues. Since the byproducts are clean, the furnaces stay cleaner and require less downtime for maintenance. Additionally the work environment is improved.

What’s next for Empower Materials? What can we expect to see in the future?

Empower Materials continues to expand the range of different types of Polyalkylene Carbonates. This is mostly driven by the need placed on us by our customers. We are also working with our customers in different applications such as glass sealing pastes, to help optimize their formulations for maximum performance.  Interest in our products continues to grow as the need increases for cleaner binders that decompose at lower temperatures. QPAC® Polyalkylene Carbonates addresses these needs.

We are committed to supporting these needs with advancements to our products (i.e. binders that decompose at lower temperatures). We are happy to discuss this further.

We can be reached at [email protected]

About Peter Ferraro

Working for Empower Materials for 11 years as Director of Business Development. Responsible for commercializing QPAC® polyalkylene carbonates in technical markets worldwide. Earlier work experience involved focusing on new business development of emerging technologies in nanoparticles, energy and digital imaging.

Educational background includes undergraduate degree in Chemical Engineering Degree from Columbia University and masters degree in business from Lehigh University.