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SSP2390 medical silicone is a series of high-purity, platinum-catalyzed, translucent silicone elastomers that range from a very soft 10 durometer to a firm 80 durometer. These medical silicones are FDA CFR, etc. 177.2600, USP Class VI*, and RoHS compliant. Two materials in this series, SSP2390-10 and SSP2390-50, are certified by the United States Pharmacopeia (USP).
SSP2390 is a series of translucent platinum-cured silicone elastomers for medical devices and medical equipment. Platinum cured silicone has stronger physical properties and lower shrinkage values than peroxide cure compounds. SSP2390 does not produce significant offgassing or catalyst byproducts.
SSP2390 medical silicone is shipped platinum pre-catalyzed and ready for use. These healthcare elastomers can be supplied as moldable compounds, sheet stock, or in rolls from .005″ to .250″ thick.
Medical silicone from SSP is available in durometer-based grades (10 to 80 Shore A) and is normally translucent. However, SSP can also supply this medical device and medical equipment silicone in colors such as red, black, gray, and white.
The base material in SSP2390 series silicones meets USP Class VI requirements, but the pigments used in custom pantones need separate testing per color by the end user. It is the responsibility of the end user to determine materials suitability and compliance with regulatory requirements.
USP Class VI silicones are biocompatible elastomers that can be fabricated into seals, gaskets, tubing, O-rings, cable jacketing, and other components for medical devices and equipment. They have low levels of extractables, chemicals that can migrate from a material at elevated temperatures or with surface exposure. Items that are made from USP Class VI silicones cannot be implanted within the human body for longer than 29 days. Consequently, most applications involve contact with skin and living tissue.
The U.S. Pharmacopeia (USP), a non-profit organization, defines the requirements for USP Class VI silicones, including a systemic toxicity test, an intracutaneous test, and an implantation test. These tests are related to the material’s end-use and account for conditions such as patient contact time. Although the USP is not a regulatory agency, its standards inform decision-making at the FDA, which defines requirements for rubber articles for repeated use in FDA 21 CFR 177.2600.
For medical products that are sold in Europe, USP Class VI silicones are available that meet the European Union’s Restriction of Hazardous Substances (RoHS) Directive 2002/95/E. USP Class VI biocompatibility requirements aren’t as stringent as those found in ISO-10993, an international standard for the biological evaluation of medical devices. However, testing medical silicones to ISO-10993 is more time-consuming and costly than is necessary for most non-implantable applications.
By using USP Class VI silicones, medical manufacturers can find the right balance between cost savings and patient protection. Still, there are some key factors to consider during material selection. These involve ingredients and certifications, colors and curing systems, and material tolerances, sizes, and lead times. The durometer, or hardness, of a USP Class VI silicone is also important since it determines the elastomer’s compressibility, which supports sealing.
Today, selecting a USP Class VI silicone isn’t a shortcut to safety. Material shortages, discontinued inputs, cost pressures, and supplier consolidation may cause a material manufacturer to substitute ingredients. If the formula for the end product changes, the elastomer may no longer meet all USP Class VI test requirements. There are also instances of materials that were never validated by a third party and vendors who stopped using certified compounds without giving notice.
To mitigate these risks, medical manufacturers need to ask their suppliers for certificates, or certs. It’s also important to understand the difference between a Certificate of Analysis (COA) and a Certificate of Conformance (COA). COAs report the test results for a specific batch of materials. By contrast, COCs simply attest to a material’s compliance. If the formula for a USP Class VI silicone changes, a COC from a supplier’s Quality Department may contain out-of-date or inaccurate information.
Normally, USP Class VI silicones are translucent. However, a compounder can add custom colors to support distinctive medical product designs. What designers need to consider, however, is that the pigments that are used may require additional testing to demonstrate compliance. There could also be compliance-related differences based on the durometer of the material. USP Class VI silicones are available in durometers ranging from 10 to 80 (Shore A) and are tested after they are cured.
The curing system that is used is especially important. Platinum-cured silicones are cleaner than peroxide-cured silicones and produce less off-gassing, the release of fumes or gases that may contain volatile organic compounds (VOCs). Platinum curing also offers greater control over cure rates and cross-linking for silicones that are more consistent in terms of appearance. Platinum-cured silicones also have stronger physical properties and lower shrinkage values.
Finally, it’s important to consider the tolerances, sizes, and lead times of USP Class VI silicones. When sheets are compression molded, they come in standard sizes based on available tooling. Continuous roll technology can produce ten times as many sheets per hour, and with tight tolerances. Importantly, rolls can also be converted to custom sheet sizes. For applications where a medical manufacturer needs a ready-to-mold compound instead, compression molding can be used for parts production.
USP Class VI silicones provide the right balance between cost savings and patient protection, but medical manufacturers need to protect themselves against supplier cost-cutting that can invalidate compliance. It’s also important to evaluate all of a material’s attributes, such as color and durometer, and to choose USP Class VI silicones that have passed third-party testing. Whether it’s for sheets, rolls, or ready-to-mold compounds, it pays to partner with a supplier whose prod