Category Archive: Filtration & Ultrafiltration

Filters: A Key Tool in the Fight Against Covid-19

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.

A Helpful Guide to Processing High Viscosity Resins

The term “viscosity” refers to the thickness or flowability of a liquid. Viscosity numbers range from 1 (water) to millions of centipoise (cP) or pascal seconds (Pa.s), 1cP = 0.001 Pa.s. Refer to our viscosity comparison chart here.

Urethane and epoxy resins with viscosities ranging from <100cP to 1,000cP are ideal for most generic casting applications. They de-air very well on their own and flow easily into closed molds, whether mixed and poured by hand or dispensed using meter-mixing equipment. However, there are many specialty materials, such as, Hapco’s Steralloy™, Filterbond™ and Hapflex™ resins that are formulated for highly-engineered applications, and because of their unique chemistries, they have a thicker viscosity than other products, making them a bit trickier to process.

When mixing and pouring by hand, Hapco always recommends vacuum degassing the mixed resin prior to pouring. With viscous materials, it can be helpful to add a few drops of a surfactant, such as Hapco’s

Anti-Air™ product, which reduces surface tension and allows the resin to degas more easily. However, vacuum degassing alone does not always alleviate air bubbles due to cavitation of the material as it flows through the mold. It may also be necessary to cure your parts under pressure using a pressure-pot or molding chamber, like Hapco’s unique X-Series Molding Chambers.

When using meter-mix dispensing, Hapco recommends designing a mold that fills from the bottom up. A general rule in this case is to design the mold so that the output opening(s) equals 2-4 times that of the input. In simple terms, if you have a 0.50” diameter input, your out-put should equal 1”-2” in diameter. This enables a “pressure drop,” which minimizes any back-pressure build-up caused by shooting a viscous material into a closed mold.

When dealing with complex mold geometry, it may be beneficial to use a two-step degassing process. After initially degassing the resin mix, fill the molds and place them under vacuum again for an additional few minutes. This not only helps to release trapped air caused by material cavitation, but it will also “pull” the viscous material into the cavity to ensure a complete fill, especially if your mold has thin walls or complex geometry. While degassing the molds, the material inside will not swell up as it did during the initial degassing step, however, it may continue to “boil” somewhat. Therefore, it is advisable to fabricate a small “chimney” around the top of your mold to prevent material from spilling out. You can do this easily with wax, putty, or a simple strip of packaging/duct tape wrapped around the top of the mold. After secondary degassing you may find the need to top off the molds to ensure they are filled to proper height, in which case you should be able to do so without the need for further degassing

Other suggestions for thinning higher viscosity materials are as follows: Pre-heat the resin to 80° – 110°F. It is really only necessary to pre-heat the thicker component which is typically the Part A for most materials. As a general rule, for every 10° you heat the material above room temperature, the material viscosity is cut in half. Bear in mind though, that heat will also cause the material to gel faster, thereby reducing your overall work time. In lieu of pre-heating the resin, you can pre-heat the molds instead. This will maintain work time for mixing, and still thin the resin viscosity as it flows into the warm molds. Another suggestion would be to add a small amount of solvent, such as, isopropyl alcohol or acetone into the resin mix. Solvents will cut the viscosity without impacting curing or material properties in most cases, as they will flash off quickly once the material starts its exothermic reaction.

The bottom line is that you will need to incorporate the proper equipment and techniques into your process in order accommodate using viscous materials. Water-thin materials require very little in the way of specialized equipment and they certainly make things easier. However, limiting your material offerings can also limit your opportunities for getting more of those “high-dollar” projects. My advice for expanding your business opportunities is to think “outside of the mold-box,” and have enough flexibility in your process to take on those jobs that nobody else wants!

Using Polyurethanes in Medical Device Applications

Medical Device Manufacture encompasses a wide range of health care products that are used to diagnose, monitor, or treat a disease or condition that affects humans. Medical technology extends and improves life. It can help alleviate pain, injury, and handicap. The endless improvement of medical technology enhances the quality and effectiveness of care and is essential in the healthcare industry.

What are the advantages of using polyurethanes in this industry?

The high strength and ease of processing of polyurethane elastomers make them the material of choice for soft durometer applications, such as instrument grips, gaskets, seals, etc. Silicone, another common polymer used in low durometer applications, is difficult to extrude and does not bond easily to other device components made of non-silicone materials. Polyurethanes eliminate the problems associated with other materials such as PVC, where the dangers of leachable plasticizers become a concern. Liquid rubbers also retain their elastomeric characteristics even at low temperatures where PVC becomes brittle.

Rigid polyurethanes also have applications in injection molded devices as component parts or for potting and encapsulating electronics. They are also commonly used for short term implants.

What organization regulates medical device applications?

The United States Food and Drug Administration’s Center for Devices and Radiological Health or “FDA” regulates medical devices.

Are there any polyurethanes that are approved for medical device applications?

Raw materials and component parts are not individually approved by the FDA. The FDA will evaluate the safety and effectiveness of a device for its intended use, and approvals are granted to the final product based on these considerations. In reality, the majority of medical devices entering the market haven’t been FDA approved. In this case, the device manufacturer must file a PMA (Pre Market Approval) on the new device.

Who is ultimately responsible for ensuring Medical Device compliance?

It is always the responsibility of the manufacturer to determine the suitability of all the component parts and raw materials that are used in the finished product.

What influence does raw material supplier test data have on FDA acceptance?

If a polyurethane supplier already has relevant toxicology data about its formulation, it can make that data available for review by the device manufacturer. The importance or desirability of certain toxicological characteristics will vary based on the intended use of the device. For example, the use of a material to make an implant requires more toxicology data than if the same material was used for a device that doesn’t contact living tissue.

Toxics Use Reduction Act

Enacted in 1989 and amended most recently in 2006, The Toxics Use Reduction Act(TURA) requires Massachusetts companies that use large quantities of specific toxic chemicals to evaluate and plan for pollution prevention opportunities, implement them if practical, and annually measure and report the results. Learn more.

TURA Reporting & Fees

Each company considered a Large Quantity Toxics User is required to file an annual toxics use report for every listed chemical it manufactures, processes, or otherwise uses above applicable thresholds.

TURA Planning Requirements

A Toxics Use Reduction (TUR) Plan is a document that provides both economic and technical evaluations of the toxics use reduction opportunities available to a company, and identifies those methods if any, that the company intends to implement.

Hapco’s Status

Under the requirements of the Massachusetts Toxics Use Reduction Act (TURA), Hapco has been submitting annual chemical use reporting forms for di-isocyanates. As part of this TURA compliance program, Hapco expects to prepare a Toxics Use Reduction Plan update by July 1, 2014 aimed at reducing the use of our reportable chemicals. This TURA Plan must address the location and performance of our process equipment, and the plan must be approved by a certified Massachusetts Toxics Use Reduction Planner to assure that it demonstrates a good faith effort to identify toxic use reduction options and it meets the requirements of the Massachusetts Department of Environmental Protection.