Polyvion HDI-T 75 is an aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI) trimer chemistry, supplied as a high-solids solution in a methoxypropyl acetate/xylene blend for lightfast two-component polyurethane coatings. Formulated at approximately 75% non-volatile content with a low residual monomer level, it delivers excellent weathering resistance, good gloss retention, and strong chemical resistance. The product is widely used across automotive refinish, industrial, and general finishing applications where long-term outdoor durability is essential.
Polyvion HDI-T 75 Overview
Polyvion HDI-T 75 belongs to the family of HDI trimer (isocyanurate) polyisocyanates, produced by cyclotrimerizing hexamethylene diisocyanate monomer into a higher-functionality, ring-structured curing agent. Supplied at roughly 75% solids in a 1:1 methoxypropyl acetate/xylene solvent blend, the product balances a moderate application viscosity with a high level of reactive NCO content, making it a practical hardener for spray-applied two-component topcoats and clearcoats.
Because the isocyanate is aliphatic rather than aromatic, coatings formulated with Polyvion HDI-T 75 resist yellowing and chalking far better than aromatic isocyanate systems under prolonged UV and outdoor exposure. Its low monomeric HDI content, achieved through the trimerization process, also supports safer handling relative to unreacted HDI monomer.
Key Features
- High NCO content HDI trimer chemistry: Polyvion HDI-T 75 delivers a high level of reactive isocyanate groups, supporting fast, dense crosslinking in two-component coating systems.
- Low monomeric HDI content: The trimerization process substantially reduces free HDI monomer relative to the parent diisocyanate, supporting safer handling and application.
- Excellent weathering and gloss retention: As an aliphatic curing agent, the product delivers outstanding resistance to yellowing, chalking, and gloss loss under UV and outdoor exposure.
- Strong chemical and mechanical performance: Coatings cured with the product show good chemical and solvent resistance along with hardness and flexibility suited to demanding automotive and industrial substrates.
- Balanced solvent-based supply form: Supplied at approximately 75% solids in a methoxypropyl acetate/xylene blend, the product offers a workable viscosity for spray application while keeping solvent load moderate.
Typical Applications
Polyvion HDI-T 75 is primarily used as the hardener component in two-component polyurethane topcoats and clearcoats for automotive refinish and industrial finishing, where high gloss, color retention, and long-term weatherability are essential performance requirements. Its high reactive-group content also makes it well suited to fast-curing coating systems seeking strong mechanical and chemical resistance.
Beyond automotive refinish coatings, the product is also applied in general industrial and protective coating systems that demand durable, lightfast performance. For higher-solids HDI trimer options with lower solvent content, formulators often evaluate Polyvion HDI-T 33 alongside this grade to compare viscosity and VOC profile.
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: Aliphatic HDI trimer (isocyanurate)
- Base chemistry: HDI trimer
- Supply form: Approximately 75% solution in methoxypropyl acetate/xylene (1:1)
- NCO content: To be confirmed based on the final specification sheet.
- Viscosity: To be confirmed based on the final specification sheet.
- Monomeric HDI content: To be confirmed based on the final specification sheet.
- Equivalent weight: To be confirmed based on the final specification sheet.
- Function: Curing agent / hardener for lightfast two-component PU coatings
HDI Trimer Chemistry & High-Solids Solvent Blend
Like other HDI isocyanurate trimers, Polyvion HDI-T 75 is produced by catalytically cyclotrimerizing three HDI monomer units into a stable, six-membered isocyanurate ring bearing three reactive NCO groups. Supplying the product at approximately 75% solids in a methoxypropyl acetate/xylene blend gives formulators a workable spray viscosity while keeping the reactive-group content high relative to more heavily diluted hardener grades, which can shorten cure times and support faster line speeds.
The solvent blend used to letdown the product should be selected to remain compatible with the methoxypropyl acetate/xylene carrier already present, avoiding solvents with reactive hydroxyl or amino groups or high water content. As with all polyisocyanate hardeners, the product is moisture-sensitive and should be protected from humidity during storage and use, since reaction with water generates carbon dioxide and can compromise film quality.
Storage Recommendations
- Store in the original, tightly sealed container, protected from moisture, heat, and foreign material.
- Recommended storage temperature: 0-30°C.
- Storage at higher temperatures will increase color and viscosity over time.
- 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 and professional use only
Formulation Guidance
When formulating two-component coatings with this curing agent, the NCO:OH stoichiometric ratio, choice of polyacrylate or polyester polyol, and catalyst package all influence pot life, cure speed, and final film properties. Formulators are encouraged to run a small formulation matrix, adjusting stoichiometry and catalyst level, to identify the process window that delivers the target balance of hardness, flexibility, and gloss for the intended substrate. For lower-viscosity applications requiring reduced solvent content, formulators may also wish to compare against Polyvion ISO-M HT10.
The product is generally not compatible with branched polyester polyols or polyether polyols, so resin selection should be confirmed against the intended co-reactant before scale-up. As with all isocyanate hardeners, moisture exclusion during storage, mixing, and application is critical to achieving consistent film quality and avoiding surface defects such as pinholing.
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 HDI-T 75: Safety & Handling
Polyvion HDI-T 75 should be handled in accordance with standard industrial hygiene practices for aliphatic polyisocyanate hardeners. 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 isocyanate vapors and mist can present respiratory and skin sensitization 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 31.