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Primers for large vehicles – polyurethane raw materials for durable coatings

Primers for commercial vehicles should provide optimum corrosions protection, smooth surfaces for the topcoat and good adhesion. They need to do this reliably even at high film thickness of the coating.

The advantages at a glance:

Outstanding corrosion protection
Very good adhesion to additional coating layers
Fast curing
Many possible combinations for the adjustment of specific properties

Curing time and sandability can be optimized by combining specific components. For primers and fillers Bayer MaterialScience provides a wide range of polyisocyanates, polyoles and reactive thinners, which can be combined to tailor the system to the desired properties. They are available as solventborne or waterbased two-component systems.

A selection of polyurethane raw materials for this application

For waterborne two-component polyurethane coatings:
Waterbased dispersions:

	Type	Solids in %	% OH on solids	Viscosity mPas at 23°C	Characteristics
Bayhydrol® A 145	PAC dispersion	45	3.3	950	For waterborne primer and top coats, good pigment wetting, high shear stability and good waterresistance
Bayhydrol® A XP 2695	PAC dispersion	41	5.0	2500	For waterborne primers and top coats, very good resistance
Bayhydrol® A 2227/1	PES-PAC Dispersion	42	3.8	1500	For waterborne primers and top coats, good pigment wetting, for stoving coatngs suitable as well

Polyisocyanate crosslinkers for waterbased dispersions:

	Type	Solids in %	% NCO on solids	Viscosity mPas at 23°C	Characteristics
Bayhydur® 3100	HDI polyisocyanate	100	17.4	2800	Hardener for two-component polyurethane coating systems and as additive for high-quality waterborne systems
Bayhydur® 304	HDI polyisocyanate	100	18.2	4000	Hardener for two-component polyurethane coating systems and as additive for high-quality waterborne coating systems
Desmodur® N 3900	HDI polyisocyanate	100	23.5	730	Low-viscosity hardener for weather-stable coating systems