Desmodur-HDI based curing agent

Covestro Desmodur BL 3175 SN heat activated HDI based curing agent for one-component polyurethane coatings

type	Blocked polyisocyanates based on hexamethylene diisocyanate
form of supply	75% 100# solvent naphtha solution
use	Use with Desmophen® products to prepare lightfast one-pack polyurethane stoving coatings; as an additive in traditional stoving systems to improve film flexibility and adhesion

Product Specifications

characteristic	Numerical value	Units of measurement	method
Non-volatile component content (0.2g/60min/80°C)	75±2	%	DIN EN ISO 3251
Viscosity, 23°C	3,300±400	mPa·s	DIN EN ISO 3219/A.3
Color value (Hazen)	≤60		DIN EN 1557
Free NCO content (revised version))	<0.2	%	DIN EN ISO 11 909

Other data*

characteristic	Numerical value	Units of measurement	method
Blocked NCO content	about 11.1	%
Viscosity, 25°C	about 2800	mPa·s	DIN EN ISO 3219/A.3
equivalent	about 378
Density, 20°C	about 1.06	g/ml	DIN EN ISO 2811
Flash point	about 45	°C	DIN 53 213/1

*The above values are general information and are not part of the product specification.

Solubility / Dilution
Desmodur® BL 3175 SN generally has good miscibility with the following solvents, but the storage stability of the resulting solutions must be tested. Desmodur® BL 3175 SN can be diluted to a 40% solids solution by weight with ketone, ester, etherester and aromatic solvents. Dilute it to a 60% solids solution (by weight) with a high-boiling aromatic solvent, such as a mixture of 100# and 150# solvent naphtha.
Aliphatic hydrocarbon solvents should not be used.

compatibility
Desmodur® BL 3175 SN is generally compatible with Desmophen® 651, 670, 680, 690, RD 181, A 160, A 265, A 365, A 450 and A 565 when given an equivalent ratio (NCO/OH=1.0). and Desmophen T 1665 miscible. It can also be used with various plasticizers, such as phosphoric acid, sulfonic acid, adipic acid and phthalate. However, the resulting mixture must be tested for miscibility.

Features/Applications
Desmodur® BL 3175 SN can be used as a curing agent in color-retaining and weather-resistant one-component polyurethane coatings. The addition of a catalyst, such as dibutyltin dilaurate (DBTL), can significantly reduce the bake temperature without affecting the storage stability. This product can be used for high-quality industrial decorative paints (electrical appliances, small components, can coatings, coil coatings, etc.) as well as primer finishers and topcoats for automotive decorative paints. Desmodur® BL 3175 can also be used as an adjuvant in conventional bake-type systems to improve film flexibility and adhesion. When Desmodur® BL 3175 is mixed with Desmophen® 651, the possible bake cycles are:
No catalyst 160℃ 60 minutes
180℃ for 15 minutes
200℃ for 7 minutes
Use catalyst 130℃ for 60 minutes
150℃ for 15 minutes
175℃ for 7 minutes
Depending on the co-reactant used and the baking time, the paint film may turn yellow when the temperature is above 160°C. When Desmodur® BL 3175 is used in coil coating systems, it is sufficient to crosslink without the addition of the catalyst DBTL at maximum plate temperatures of about 241°C and above. If adding 1% DBTL (calculated by resin solid content), the same effect can be obtained at the maximum board temperature of about 224 ℃.

Safety: Hazard Identification
Flammable, may be irritating to the skin and mucous membranes, and can easily cause allergies, so special care must be taken when using it. Harmful to aquatic life, may cause long-term adverse effects in the aquatic environment.
Its vapors may cause drowsiness and dizziness.
The Safety Data Sheet (028952) must be strictly followed. It includes information on labelling, transportation and storage, as well as information on product use, product safety and ecology.