NMP-Free Aliphatic Polyurethane Dispersions for Medical & Dental Applications

SIWO US Inc. is a research-driven leader in waterborne polyurethane dispersions with a proven track record of innovation and sustainable solutions. Our aliphatic, NMP-free polyurethane dispersions (PUDs) are engineered specifically for the stringent requirements of the medical and dental industries. These high-performance coatings and adhesives combine biocompatibility and non-toxicity with exceptional flexibility and durability. In medical and dental applications, materials must be safe for skin or mucosal contact while remaining robust under stress. SIWO’s aliphatic PUDs meet these demands: they form tough, elastic films that resist yellowing or degradation, yet contain no toxic solvents like N-methylpyrrolidone (NMP). This means safer handling and compliance with global regulations that increasingly restrict NMP use. As a result, SIWO’s products support both patient safety and sustainable, employee-friendly manufacturing.

Technical Features

Waterborne & NMP-Free: SIWO’s PUDs are 100% aqueous formulations. By eliminating NMP and other hazardous solvents, these dispersions offer low odor and low VOC content. This makes them safer for operators and patients alike, and aligns with stringent environmental and workplace-safety standards. (NMP has been identified as a toxic reproductive hazard in California and by EU regulators, driving demand for NMP-free chemistries.)
Aliphatic Polyurethane Chemistry: Based on aliphatic polyurethane (often polycarbonate-based diols), our dispersions yield non-yellowing, UV-stable films with excellent chemical stability. The cured films are inherently biocompatible and resist degradation by body fluids, cleaning agents, or sterilization processes. In fact, medical-grade TPU (thermoplastic polyurethane) films are prized for strength, clarity, and biocompatibility; SIWO’s PUDs achieve similar performance in a waterborne system.
High Elasticity and Flexibility: These PUDs form elastomeric coatings with very high elongation (often several hundred percent) and low modulus. The films remain soft and flexible even at low temperatures, allowing comfortable, conformable use on skin or in tubing. This elasticity ensures gentle adherence and patient comfort (important for wearable devices and wound dressings), while still providing enough resilience to apply corrective forces in dental aligners. In fact, clear aligner materials based on polyurethane are chosen for their strong mechanical and elastomeric qualities and abrasion resistance.
Tough, Durable Films: Despite their softness, the cured coatings are tough. They exhibit excellent tensile strength and abrasion resistance, helping medical devices and wearables survive handling and repeated flexing. For example, one NMP-free, aliphatic PUD is described as forming “tough, flexible films with very good adhesion properties” along with outstanding UV and water resistance. These features translate to long-lasting coatings on tubing, sensors, or device housings.
Excellent Adhesion and Chemical Resistance: Our PUDs bond well to a variety of substrates (plastics, metals, rubber, textiles), which is critical in multi-material medical assemblies. They resist water, oils, and disinfectants, and maintain integrity in the moist environment of the human body or clinical settings. The low water permeability and hydrolysis resistance of these aliphatic formulations helps prevent bacterial intrusion and degradation over time.
Non-Toxic and Skin-Safe: Aliphatic PUDs are inherently low in extractables and leachables. When fully cured, they pass standard biocompatibility tests (ISO 10993) for skin contact, matching medical-grade PU films that meet FDA/ISO standards. The dispersions themselves have minimal skin irritation and very low cytotoxicity – key for products like wearable sensors or adhesive bandages that are in prolonged contact with skin.

Application Areas

SIWO’s aliphatic PUDs serve diverse medical and dental uses where flexibility and biocompatibility are essential:

Biocompatible coatings: These waterborne PUDs can be applied as thin, transparent films on medical devices, wearables, or wound-care substrates. For example, catheter or cannula surfaces, sensor housings, and implantable device coatings benefit from PU’s durability and softness. The PU film acts as a breathable, flexible barrier, in wound dressings, for instance, polyurethane films are often used as a protective layer because they offer flexibility, breathability, and transparency for wound monitoring. Likewise, skin-contact coatings on gels, fabrics, or foams can be engineered to be non-adhesive, antimicrobial, or lubricious as needed.
Wound dressings: Our dispersions are ideal for adhesives and films in advanced wound care. They provide gentle adhesion to skin without irritation, and can incorporate additives for moisture control. Polyurethane-based dressings often use a microporous PU film backing that retains a moist environment for healing while preventing external contamination. SIWO’s PUDs can form these breathable, waterproof membranes that conform to the wound site. In addition, they can be used in gel or foam wound dressings as the elastomeric matrix material, combining strength with patient comfort.
Dental aligner resins: In orthodontics, clear aligners require materials with high elasticity, good transparency, and low irritation. While many aligners today are thermoformed plastics, photo-curable or cast PU resins are an emerging alternative. SIWO’s PUDs can be formulated into flexible dental resins or adhesives for aligner attachments. Polyurethane is known for strong mechanical and elastomeric qualities, abrasion and chemical resistance, making it suitable for the moist, variable environment of the mouth. Our waterborne PUDs can help create aligner materials that maintain force over weeks of wear while ensuring any residual material is safe if contacted.

Other medical devices: Beyond these key areas, aliphatic PUD coatings and adhesives are used in tubing (IV lines, catheters), flexible membranes (inflatable cuffs, respiratory masks), wearable health monitors, surgical drapes, and more. Anywhere a polymer film or adhesive must be flexible, non-toxic, and durable, our medical-grade dispersions can be tailored to fit. For example, medical tubing often uses PU for its biocompatibility and comfort; a waterborne aliphatic PUD coating on extruded tubing can improve flexibility and bonding with sensors or fabrics without compromising safety.

Product Advantages

SIWO’s aliphatic PUD line offers multiple advantages to both engineers and procurement professionals in the medical/dental field:

Patient and Skin Safety: Formulations are non-toxic and hypoallergenic. Eliminating NMP and similar solvents means no residual irritants. The cured films are inert and pass rigorous cytotoxicity tests. This ensures regulatory compliance (ISO10993-5/10) and patient comfort.
High Performance: These dispersions can be optimized for required properties. For instance, varying molecular weight and crosslink density tunes elasticity, tensile strength, and hardness. Additives (antimicrobials, UV stabilizers) can be incorporated. SIWO’s R&D support means you get a solution with proven performance in specific use-cases.
Process Versatility: Waterborne PUDs can be applied by spray, dip, or coating processes, and can even be 2-component crosslinked on-the-job. They cure at low temperatures (room temp to 80°C) without harsh solvents. This reduces equipment costs and avoids coating defects like solvent entrapment.
Durability and Stability: The cured polymer resists abrasion, hydrolysis, and UV. For example, SIWO’s PUDs, like many aliphatic PUs, deliver excellent UV and water resistance. Devices using these coatings enjoy a long service life even in sterilization or outdoor sterilization conditions. The materials also have low creep, so, say, a dental aligner or compression garment retains its shape over time.
Proven Track Record: SIWO US’s decades of PUD expertise means reliability. Our dispersions have been applied successfully in sensitive markets worldwide. We support customers with datasheets, testing, and certification data. As a result, engineers get materials that work out-of-the-box, and purchasing teams can count on consistency from batch to batch.

Sustainability Benefits

Our aliphatic PUDs support green manufacturing and end-use sustainability:

Eco-Friendly Formulation: The waterborne nature means minimal VOC emissions and no flammable solvents. This reduces environmental impact and improves workplace air quality. By avoiding NMP (a targeted reproductive toxicant), we adhere to strict environmental and safety regulations globally.
Safe Production & Handling: Without hazardous solvents, coating lines are safer and simpler. Handling precautions and disposal costs are lower. Products meet REACH and RoHS standards for restricted substances. (For example, SIWO’s waterborne line is explicitly marketed as “low odor and NMP-free” with high tensile strength and abrasion resistance.)
Product Longevity: The durability of aliphatic PUD coatings means devices last longer, reducing waste. Because these polymers resist degradation, fewer replacements or rework are needed. In wound care, a breathable PU film dressing can often be left in place longer than a bandage without needing replacement, minimizing medical waste.
Resource Efficiency: Waterborne processing consumes less energy (no solvent recovery) and generates less volatile waste. SIWO’s manufacturing is research-driven to optimize solid content (often 30–60% solids) and minimize water use. This aligns with customer CSR goals and helps secure green certifications.

By combining expert polymer science with a focus on safety and sustainability, SIWO US’s aliphatic, NMP-free polyurethane dispersions enable advanced solutions in medical and dental care. From biocompatible coatings and breathable wound dressings to flexible dental aligner resins, our products deliver the performance and peace-of-mind that engineers, clinicians, and procurement professionals demand.

NMP-Free Aliphatic Polyurethane Dispersions for Medical & Dental Applications

Technical Features

Application Areas

Product Advantages

Sustainability Benefits

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