Polyvion ISO-M 31 is a blocked aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI) chemistry, supplied as a solvent-based solution for one-component polyurethane stoving systems. Formulated as a latent curing agent, it remains storage-stable at room temperature and only becomes reactive once the blocking group is thermally released, allowing formulators to premix a single-pack coating that cures cleanly under stoving conditions. The product is widely used in industrial finishing, coil, and can coating systems where lightfastness, flexibility, and reliable crosslinking are required.
Polyvion ISO-M 31 Overview
Polyvion ISO-M 31 belongs to the family of blocked aliphatic polyisocyanates in which reactive NCO groups on an HDI backbone are temporarily capped with a blocking agent, most commonly an oxime-type compound. This capping renders the product unreactive toward hydroxyl-functional resins at ambient temperature, which is what makes true one-component polyurethane stoving systems possible. During stoving, heat drives off the blocking agent, regenerating free isocyanate groups that crosslink with the resin to build the final film network.
Because the isocyanate is aliphatic rather than aromatic, coatings formulated with Polyvion ISO-M 31 retain good color and gloss stability under UV exposure, avoiding the yellowing typically associated with aromatic isocyanate chemistry. The product is supplied ready to use as a solvent-based solution, simplifying incorporation into finished one-component formulations.
Key Features
- Blocked aliphatic polyisocyanate (HDI-based): Polyvion ISO-M 31 is built on hexamethylene diisocyanate chemistry, giving it good weatherability and non-yellowing performance compared with aromatic curing agents.
- Designed for one-component PU stoving systems: The product is formulated for premixed, single-pack coatings that only crosslink once the blocking group is thermally released during stoving.
- Lightfast curing behavior: Films cured with the product show good gloss retention and resistance to yellowing on extended outdoor or UV exposure.
- Good storage stability prior to curing: Because the isocyanate groups are capped, one-pack formulations containing this curing agent can be stored for extended periods without premature gelation.
- Broad plasticizer and resin compatibility: The product is generally compatible with common coating plasticizers and hydroxyl-functional resin systems, supporting flexible formulation design.
Typical Applications
Polyvion ISO-M 31 is primarily used in one-component polyurethane stoving coatings for industrial finishing applications, where it supports reliable crosslinking after thermal cure without the pot-life limitations of two-component systems. Its blocked chemistry makes it well suited to coil and can coating lines, where coatings are applied, then cured rapidly in continuous stoving ovens.
Beyond coil and can coatings, Polyvion ISO-M 31 is also applied in primer surfacers and topcoats for automotive finishing, as well as in coatings for electrical appliances and small industrial components where lightfastness and flexibility are priorities. For projects requiring a two-component aliphatic system instead, formulators often evaluate Polyvion HDI-T 33 alongside blocked grades to compare cure speed and film performance.
Technical Specifications
The product is characterized by the following indicative technical parameters; confirmed values will be provided in the final product specification sheet.
- Chemical type: Blocked aliphatic hexamethylene diisocyanate (HDI) polyisocyanate
- Base chemistry: HDI
- Supply form: Solvent-based solution
- Blocking chemistry: Oxime-type (indicative)
- NCO content: To be confirmed based on the final specification sheet.
- Viscosity: To be confirmed based on the final specification sheet.
- Deblocking temperature: To be confirmed based on the final specification sheet.
- Function: Latent curing agent for PU stoving systems
Deblocking & Curing Behavior
Blocked isocyanates such as this one work by temporarily deactivating the highly reactive NCO group with a small-molecule blocking agent. At room temperature, the blocked product is essentially inert toward hydroxyl groups, allowing the isocyanate and resin to be combined into a single stable package. Once the coating is exposed to stoving temperatures, the blocking agent dissociates and evaporates or reacts away, freeing the isocyanate to crosslink with the resin and build the cured film.
Stoving temperature and cure schedule are formulation-dependent, and catalysts such as dibutyltin dilaurate are commonly used to lower the effective deblocking and cure temperature without compromising the storage stability of the one-component system. Formulators should confirm cure schedule, catalyst level, and deblocking behavior through bench trials before scaling to production lines.
Storage Recommendations
- Store in a dry, well-ventilated area away from moisture, heat sources, and direct sunlight.
- Keep containers tightly closed to prevent moisture ingress, which can react with free or regenerated isocyanate groups.
- Recommended storage temperature: To be confirmed based on the final specification sheet.
- Shelf life: To be confirmed based on the final specification sheet.
Documentation & Compliance
Each shipment of the product is supported by standard quality and compliance documentation to help customers manage incoming inspection, formulation approval, and downstream regulatory reporting.
- Certificate of Analysis (COA): Provided per batch
- Safety Data Sheet (SDS): Mandatory prior to handling
- Labels: Prepared in accordance with applicable regulations
- Industrial use only
Formulation Guidance
When formulating with this curing agent, the stoichiometric ratio between isocyanate and hydroxyl-functional resin, the choice of catalyst, and the stoving schedule all influence final film hardness, flexibility, and gloss retention. Formulators are encouraged to run a small formulation matrix, varying catalyst level and cure temperature, to identify the process window that delivers the target balance of hardness and flexibility for the intended substrate.
Because the product is aliphatic, it is generally well suited to exterior-durable coatings where color and gloss stability under UV exposure are important. As with all one-component stoving systems, moisture exclusion during storage and application is critical to maintaining pot stability and achieving consistent cure.
Packaging & Logistics
- Packaging: Approved industrial packaging
- MOQ: Subject to packaging configuration
- Lead time: Indicative lead time, to be confirmed upon order acceptance
- Incoterms: Quoted case by case
Polyvion ISO-M 31: Safety & Handling
Polyvion ISO-M 31 should be handled in accordance with standard industrial hygiene practices for blocked polyisocyanates. Users are advised to review the Safety Data Sheet prior to handling and to implement appropriate personal protective equipment and engineering controls as specified therein, since regenerated isocyanate groups during stoving can present respiratory hazards if ventilation is inadequate. As with all curing agents, small-scale compatibility and cure trials are recommended before full-batch formulation to confirm performance in the target system.
Safety Data Sheet and destination-compliant labeling information for the product are available upon request. For related curing agent options, see also Polyvion HDI-T 33 and Polyvion ISO-M HT10.