Covestro HDI Blocked Curing Agent Desmodur BL 3575 MPA SN

Features Of Covestro HDI Blocked Curing Agent Desmodur BL 3575 MPA SN

1. Highly stable blocked isocyanate based on hexamethylene diisocyanate (HDI) with methyl propyl amine (MPA) blocking agent.

2. Excellent storage stability at ambient temperature with low volatility and minimal risk of premature deblocking.

3. Enables one-component (1K) polyurethane formulations with controlled thermal curing onset around 120–140 °C.

4. Delivers superior film hardness, flexibility, and chemical resistance in cured coatings.

5. Compatible with hydroxyl-functional acrylics, polyesters, and polyols for high-performance industrial coatings.

Typical Applications Of Covestro HDI Blocked Curing Agent Desmodur BL 3575 MPA SN

1. Automotive OEM and refinish clearcoats requiring high gloss and durability.

2. Industrial maintenance coatings for metal substrates including machinery and agricultural equipment.

3. Plastic coatings for automotive interior trim and consumer electronics housings.

4. Wood coatings for premium furniture and flooring requiring low-temperature cure capability.

5. Coil coatings where balanced crosslink density and processing safety are critical.

Specifications Of Covestro HDI Blocked Curing Agent Desmodur BL 3575 MPA SN

Covestro HDI Blocked Curing Agent Desmodur BL 3575 MPA SN – Frequently Asked Questions (FAQ)

Q1: What is the primary function of Desmodur BL 3575 MPA SN in coating and adhesive formulations?

A: Desmodur BL 3575 MPA SN is a thermally activated, blocked aliphatic polyisocyanate curing agent designed to provide excellent storage stability at ambient temperature while enabling efficient crosslinking upon heating. It is commonly used to impart enhanced hardness, chemical resistance, and weatherability to high-performance coatings and reactive adhesives.

Q2: At what temperature range does the blocking agent deprotect to initiate crosslinking?

A: The MPA (methyl propionate) blocking group undergoes thermal deblocking typically above 120 °C, with full reactivity generally achieved between 130 °C and 160 °C depending on formulation composition, film thickness, and heating profile. Lower cure temperatures may be possible with catalytic assistance.

Q3: How does Desmodur BL 3575 MPA SN compare to other blocked HDI derivatives in terms of volatility and handling safety?

A: As an MPA-blocked derivative, Desmodur BL 3575 MPA SN offers low volatility and reduced inhalation risk compared to some phenol- or oxime-blocked alternatives. Its physical form—typically a low-viscosity liquid—facilitates metering and homogeneous blending without requiring solvents or elevated temperatures during incorporation.

Q4: Is this product compatible with hydroxyl-functional acrylics and polyesters in two-component systems?

A: Yes, Desmodur BL 3575 MPA SN is formulated for compatibility with standard hydroxyl-terminated resins, including acrylics, polyesters, and alkyds. It delivers balanced pot life at room temperature and robust film formation after thermal activation, making it suitable for industrial coil, automotive refinish, and specialty plastic coating applications.