Desmophen - Polyester

Covestro Desmophen® 670 BA Lightly branched hydroxyl polyester for flexible and weather-resistant formulations

type	Lightly branched hydroxyl polyester
form of supply	About 80% dissolved in butyl acetate solution
use	Mainly used as co-reactant of Desmodur® N75 and N3390 to prepare flexible coatings with good weather resistance

Specifications

characteristic	Numerical value	Units of measurement	method
Hazen color value	≤150		DIN EN 1557
Acid value	1.8±1	mgKOH/g	DIN EN ISO 2114
Viscosity, 23°C	3,000±400	mPa·s	DIN EN ISO 3219/A.3
Non-volatile component content (1g/1h/125℃, convection oven)	80±1	%	DIN EN ISO 3251
Hydroxyl content	3.5±0.3	%	DIN 53240/2
water content	≤0.1	%	DIN 51777/1

Other data*

characteristic	Numerical value	Units of measurement	method
equivalent	about 485
Density, 20°C	about 1.11	g/m	DIN EN ISO 2811-2
Flash point	about 32	°C	DIN EN ISO 2719

*This data is general information and is not part of the product specification.

Solubility/Dilution
Desmophen® 670BA is soluble in ethyl acetate, butyl acetate, 1-methoxypropyl acetate-2, methyl ethyl ketone, methyl isobutyl ketone, toluene and mixtures of these solvents. However, the storage stability of the prepared solution must still be tested. The xylene solution of this product will separate when the solid content is less than 40%. Use polyurethane grade solvent (water content <0.05%, no other reactive impurities).

compatibility
Desmophen® 670BA is miscible with many polyester Desmophen® based products and many ethylene copolymers. But the compatibility of the mixture must be tested. Desmophen® 670BA has limited compatibility with Desmophen® polyacrylates and cellulose acetate butyrate.

application
Coatings made of Desmophen® 670BA mixed with Desmodur® N75 or N3390 have excellent weathering stability and outstanding low temperature flexibility. This type of coating is mainly used for coating plastic articles and force drying at 80°C. Desmophen® 670BA can also be added to other two-component polyurethane systems to improve flexibility.

store
This product is stable for at least 6 months when stored in an airtight container below 30°C. Under certain conditions (below 15°C or long-term storage), the product may become cloudy, and when heated to about 40°C, the product will return to its original state. Adding a solvent during preparation can also make the solution clear, and the product quality is not affected.