Category Archive: High Performance Plastics
For over 4,000 years, the evolution of the filter has been directly linked to the improvement of human health and life expectancy. The first great civilizations, like the ancient Egyptians, used sand and gravel as filter media to improve the taste and appearance of water. Today, filters have become an essential component to our entire way of life. They are found in countless industries, manufacturing facilities, processes, and in many cases, the end products themselves. More importantly, filters are enabling the tools and devices that are essential to defeating this invisible enemy and returning the world to some semblance of normalcy.
Since the onset of this pandemic, our society has gained a new appreciation for respirators, ventilators, and vaccines, as well as the vital role they play in saving lives and preventing future outbreaks. Like everything else in our modern industrial society, these life-saving tools all rely on specialized filter media and advanced filtration technology to function. It is obvious how filters are utilized in equipment like respirators and ventilators, but when it comes to vaccines the use of filter technology is not immediately apparent.
How are filters used for making vaccines?
A successful vaccine is the result of complex scientific processes that include the concentration of proteins and enzymes, blood plasma purification, virus and bacteria concentration and removal, as well as cell harvesting, clarification and washing. These procedures are all enabled by specialized filters and equipment.
Some common methods used in bioprocessing include membrane filtration, tangential flow filtration, centrifugation, and depth filtration. Implementing the proper filtration technology can have a positive effect on yield, product consistency, and overall efficiency of the entire operation.
What types of filters are used?
Hollow fiber filters possess excellent filtration performance and are commonly used in dialysis, water purification, reverse osmosis, separation of components from biological fluids, and cell culture devices to name a few.
Tangential flow filtration (TFF) systems are used extensively in the production of vaccines and other pharmaceutical drugs. They can be used to remove virus particles from solutions, clarify cell lysates, harvest and retain cells, and they can concentrate and desalt sample solutions ranging in volume from a few milliliters up to thousands of liters.
A HEPA (High Efficiency Particulate Air) filter works by forcing air through a fine mesh that traps harmful particles such as dust mites, pollen, pet dander, smoke, and even airborne viruses. HEPA filters are used in applications where contamination control is required, such as the manufacturing of semiconductors, disk drives, medical devices, food and pharmaceutical products, as well as in homes, vehicles, and hospitals.
How is Hapco involved in the filtration and ultrafiltration industry?
Hapco has been custom formulating adhesives, sealants, and potting compounds for some of the world’s largest filter manufacturers for over 40 years. Our materials and processing equipment are a key component to manufacturing a wide variety of specialized filters. As a preferred supplier to corporations like MilliporeSigma, Pall Life Sciences, and Koch Membranes, we take pride in our ability to provide customers with the highest quality polymers and the most reliable processing equipment available.
As we look to a post-pandemic future, our chemists are developing new formulations and processing methods to meet the needs of filter manufacturers around the world. We are currently conducting in-house testing on Filter-bond™ R-3590: a new epoxy formulation for the filtration market that is both Bisphenol-A (BPA) and nonylphenol-free.
What other Hapco products are used to manufacture filters?
The Filter-bond™ series was first developed in the 1980’s for various filtration and ultrafiltration applications. It includes formulations that do not contain aromatic amines or carcinogenic or mutagenic materials, systems that can be used to pot moist membrane material in place without foaming, and systems that are easily trimmed when used for pre-potting filters. Filter-bond™ includes a line of flexible and rigid materials to meet a wide variety of filtration applications. All Filter-bond™ products are compatible with Hapco’s MiniFIL™ and RapidFIL™ dispensing machines, which are used for potting or encapsulating various filter media.
Final Thoughts
Filters are one of mankind’s greatest achievements and a major reason our life expectancy has increased dramatically over the past 200 years. They clean the air we breathe, the water we drink, the fuel that moves us forward, and the medicine that keeps us healthy. Without them, there is simply no way to manufacture the life-saving and preventative drugs that offer us a light at the end of this tunnel.
Fun Fact: Hippocrates (460-370BC) was the first major proponent of water filtration in recorded history. He advised people to first boil, then filter water through two sewn together pieces of cloth which eventually came to be known as a Hippocrates’ Sleeve.
Part 1 – Making the Mold
In this article, we show you step by step, how to duplicate a complex pattern using Hapco’s high performance materials and equipment.
After taking measurements of the pattern and creating a drawing to outline our plan, we constructed a mold box using medium density overlay.
Orient the pattern inside the mold frame in a manner that will maximize the flow of material and minimize the amount of air that could get trapped. The paper represents cutouts that will reduce waste and save on material costs.
Pieces of cardboard were cut and layered to follow the shape and contours of the unicorn. This creates a foundation for a layer of clay that will represent the parting line for the two mold halves.
The clay is carefully smoothed out up to the halfway point to raise the part from the board and create a parting line along the middle.
Hapsil™ 360 is mixed thoroughly and degassed in an X-Vac™ Chamberto remove any trapped air before pouring.
Hapsil™ 360 is slowly poured over the pattern until it reaches the top of the mold box.
The silicone is left to cure overnight at room temperature.
Once the silicone has cured, the cardboard and clay are removed. The cured silicone mold half is temporarily removed from the frame for easier cleaning.
The pattern is temporarily removed allowing the mold to be cleaned thoroughly with isopropyl alcohol.Grease-It™ 5 release agent is also sprayed on the mold.
Once the unicorn pattern and mold are placed back in the frame, a final coat of Grease-It™ 5 is evenly applied over the surface.
Step 5 is repeated and the Hapsil™ 360 is poured evenly over the part in a thin, steady stream. It is best to pour from one side to allow the air to escape as it’s filling.
The uncured silicone is allowed to cure at room temperature overnight.
The silicone is removed from the frame and separated. Once the pattern is demolded, the silicone is cleaned thoroughly with isopropyl alcohol.
It is important to understand how the mold will be oriented and to consider where air may get trapped. Vents are carved out of one mold half to give air bubbles a path to escape.
The two mold halves are separated and placed in an oven at 125°F for 8 hrs. It is important to separate the mold halves to allow any oils or
residue to flash off.
A hole is cut where the material will be poured into. This represents the top of the mold.
The silicone rubber is completely supported by the wooden box. The two side pieces are screwed into place and the mold is rotated so that the hole is on the top. It is now ready for casting.
To learn how we cast a clear part using Ultraclear™ 480N-40, view Part 2- Casting the Unicorn.
Polypropylene (Impact, heat and flex)
Polypropylene has a tensile strength of 4,500-6,000 psi, an elongation of 1-600% and an izod impact of 2.2-no break at all. For the best simulator of these properties, Hapco would recommend using Hapflex 666 or Hapflex 671. Both products come in slow and fast gel times and are available in a flame retardant version.
ABS (Impact resistance)
ABS has a tensile strength of 5,500-7,500 psi, an elongation of 5-25% with a flexural strength of 11,000 – 13,000 psi. Hapco’s Tuffalloy™ Series is a great candidate for simulation of ABS. You might also consider Ultralloy 109 or Hapflex 671, both of which have exceptional mechanical properties.
High-Temperature “Rubber” (heat resistance)
Hapflex™ 666 has a heat deflection temperature of 110°C and a service temperature of 135°C and Hapflex 671 has an HDT of 130°C and service temperature as high as 150°C (300°F). These would be our best recommendations for a semi-flexible product with high heat resistance.
Nylon 6-6 (Bearing and roller-type parts/gears)
Nylon comes in a variety of types, with each different type having a variety of grades. On average, it has a tensile strength of 7,500-11,000 psi, and an elongation of 30-100% with an izod impact of .6-2.2. Ultralloy 200 Series or Hapflex 671 would compare favorably to Nylon. By adding 20-25% milled glass to the products, you can make them very strong.
Polycarbonate (High impact with some flexibility)
Polycarbonate has a tensile strength of 9,000-10,500 psi with an elongation of 110-120% and a flexural strength of 12,500-13,500 psi. For simulating this product we would recommend using Hapco’s Ultralloy 200 Series, Ultralloy 900 Series or the Tuffalloy Series. Ultralloy 912 has exception impact strength, high HDT and is rate UL 94V0 @ .125” thick.
Polystyrene (Like polycarbonate but cheaper in production)
Polystyrene has a tensile strength of 5,200-7,500 psi, an elongation of 1.2-2.5% and flexural strength of 10,000 to 14,000 psi. For simulating this material we would recommend using Hapco’s Ultralloy 108 or 109.
Santoprene (rubber parts)
Santoprene is a thermoplastic rubber that comes in hardnesses ranging from 35 Shore A to 50 Shore D. IT exhibits good resistance to fatigue and has high tear strength. It also has good chemical resistance to many acids and aqueous solutions and performs well in thermo-cycling applications. For simulating these characteristics we would recommend the entire Hapflex™ Series which ranges from a 25A to 70D in hardness.
This video will teach you how to create a mold with a high performance surface material and a machinable, low cost backup, which in this case is Hapco’s Fill-Its/Haprez combo. The reason for creating a mold like this is to cut down on the thickness of the Hapflex 668, a high performance material, which can be expensive. This method also reduces the amount of shrinkage that would normally occur as a result of casting large quantities of liquid plastic around an odd shaped pattern.
If you would like to download a printable version of this tutorial, click here.
