Medical Hot Melt Pressure Sensitive Adhesive Standards
Medical Hot Melt Pressure Sensitive Adhesive (HMPSA) has specific requirements and standards for its application in medical tapes. Widely utilized in the production of medical supplies such as medical tapes, infusion patches, and wound dressings, HMPSA exhibits both hot melt and pressure-sensitive properties. It requires specialized equipment for heating and melting during the manufacturing process, demonstrating its hot melt characteristics. Once applied, medical adhesive products like tapes and wound dressings adhere upon finger pressure, showcasing their pressure-sensitive nature. In the medical tape market, HMPSA must meet certain criteria beyond just applicability and thermal stability. It should possess properties such as non-irritating, conformability, and breathability.
- Applicability: HMPSA can be applied using special nozzles or rollers onto various substrates. However, HMPSA used for medical tapes typically has high fluidity, which may lead to overflow when applied to porous substrates. Additionally, many medical tape substrates cannot withstand high heat and may stretch, deform, or even break during application. To address these challenges, manufacturers often apply HMPSA to release paper that can withstand high temperatures before transferring it to various substrates.
- Non-irritating: Solvent-based adhesives commonly used in medical tapes can cause skin allergies, necessitating the addition of zinc oxide powder to the adhesive. Zinc oxide serves two purposes: reducing the allergenicity of solvent-based adhesives and enhancing moisture absorption or sweat-wicking capabilities.
- Conformability: Natural tackifying resins such as rosin or esterified rosin are unsuitable for medical tapes. Therefore, achieving skin conformability relies on the inherent softness and wetting properties of HMPSA itself, known as tackiness. When designing HMPSA for medical tapes, emphasis should be placed on its flowability on human skin. Once applied, the tape should continuously wet and adhere to the skin surface. Ideally, the tape should not lift or peel off due to bending or movement of joints.
- Breathability: To minimize skin irritation, HMPSA for medical tapes typically excludes polar substances (hydrophilic polymers) as components since they do not absorb moisture or sweat. To achieve adequate breathability, pinholes can be punched in the tape substrate along with the adhesive after application, or special coating equipment can create non-full coverage, leaving breathable holes on the adhesive surface. Both methods allow medical tapes to attain a certain level of breathability.
