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Polyurethane top coats for industrial coatings- for long lasting high quality surfaces

One- and two-component polyurethane coating systems are particularly suitable for top coats on high-quality industrial goods. They feature great physical and optical properties and have an excellent durability. Depending on their final application they can be classified in these categories:

The selection of the coating system depends among other considerations on the size and geometry of the parts to be coated. Generally, two-component polyurethane coatings are used when the parts are too big or too complex for one-component stoving coatings. Waterborne and high solids are the choice, when the primary goal is the reduction of solvents. Productions facilities and parts permitting, UV curing top coats can be an alternative. Since UV curing takes place very quickly, the parts can immediately be used for subsequent processing.

For highly efficient coating processes the polyaspartic acids (Polyaspartics) take a very important role. With polyaspartics films can be applied in high thickness, in one pass and bubble-free, replacing several coating layers compared to classical coating systems. Even 1-coat applications are possible with these products (direct-to-metal, DTM). Their high solid character and the rapid film building are additional advantages. Find out more in the section Corrosion protection - Polyaspartics and in the Technology section under High Solid Systems.

New developments in the field of waterborne two-component polyurethane dispersions enable the formulation of low-VOC systems that are well within the VOC limits set by current legislation and offer users maximum freedom in the choice and quantity of co-solvent used. With rapidly drying coating systems, production efficiency can be significantly increased, energy costs lowered as a result of lower oven temperatures compared to standard systems and the CO2 balance thereby improved, all without having adverse effects on pot life.

The property profile of these new waterborne products with respect to gloss, drying and resistance properties is at a comparable level to that of solventborne systems, in some cases even exceeding it.

Examples from a wide range of products suitable for industrial coatings

Polyurethanes for one- and two-component waterborne systems
Waterbased dispersions:

	Type	Solids in %	% OH on solids	Viscosity mPas at 23°C	Characteristics
Bayhydrol® A 145	Polyacrylate dispersion	45	3.3	950	Good pigment wetting, high shear resistance, for high-gloss topcoats with good adhesion and good resistance against solvents and water
Bayhydrol® UH 245	Polyester polyurethane dispersion	45	2.3	850	For air and force drying coatings with good corrosion protection properties
Bayhydrol® A 2470	Polyacrylate dispersion	45	3.9	2000	For clear- and top coats with good resistance properties
Bayhydrol® A XP 2770	Polyacrylate dispersion	44,5	3.9	2000	Low VOC variant of Bayhydrol A 2470 without flash point
Bayhydrol® UH XP 2592	Polyester polyurethan dispersion	45	2.1	300	For air and force-drying high gloss coatings with good corrosion protection
Bayhydrol® A 2601	Polyacrylate dispersion	45	3.9	2000	For clear- and top coats with good resistance properties and very fast drying
Bayhydrol® A XP 2801	Polyacrylate dispersion	44,5	3.9	2000	Low VOC variant of Bayhydrol A 2601 without flash point and with very rapid drying without adverse effect on pot life
Bayhydrol® A 2620	Polyacrylate dispersion	48.5	3.0	1600	For clear- and top coats with fast drying and low VOC
Bayhydrol® A XP 2695	Polyacrylate dispersion	42	5.0	2500	For clear- and top coats with very good resistance properties (anti-graffiti properties)
Bayhydrol® U XP 2750	Polyurethan dispersion	43	3.6	1000	Hydrophilic crosslinker in combination with HDI-based greades to enhance drying properties
Bayhydrol® U XP 2766	Polyurethane dispersion	44,5	3,9	2000	For clearcoats and topcoats with very high gloss and hardness, ideal for mixing with other dispersions to increase gloss, free of co-solvent

Polyisocyanate crosslinkers for waterbased :

	Type	Solids in %	% NCO on solids	Viscosity mPas at 23°C	Characteristics
Bayhydur® 3100	HDI polyisocyanate	100	17.4	2800	Hardener also as additive for high-quality waterborne coatings
Bayhydur® 304	HDI polyisocyanate	100	17.4	2800	Hardener also as additive for high-quality waterborne coatings
Bayhydur® XP 2655	HDI polyisocyanate	100	21.2	3500	As a hardener component for two-component polyurethane systems that can be very easily incorporated and as an additive for high-quality waterborne coating systems
Bayhydur® XP 2487/1	HDI polyisocyanate	100	20.6	5400	As a hardener component for two-component polyurethane systems that can be easily incorporated and as an additive for high-quality waterborne coating systems with good chemical
Bayhydur® XP 2759	IPDI polyisocyanate	70	15.7	6500	Hydrophilic crosslinking partner in combination with HDI grades for improving drying behaviorl
Desmodur® N 3600	HDI trimer	100	23.0	1200	For high solid coatings, high gloss, good chemical and weather resistance, lightfast, good mechanical resistance
Desmodur® N 3900	HDI trimer	100	23.5	730	Forhigh-solids coatings, high gloss, chemical and weather resistance, good lichtfastness and high mechanical stability
Desmodur® N 3800	HDI trimer	100	11.0	6000	Mixed with Bayhydur and Desmodur grades to flexibilize waterborne two-component polyurethane systems

Polyurethanes for one-component waterborne stoving systems

Polyurethanes for one-component solventbased systems

Polyurethanes for two-component solventbased systems

Polyaspartic acids (Polyaspartics) for high solid systems

Some starting formulations (examples)

RR 6083	Polyurethane stoving top coat (Desmophen® T 1665)

RR 6050	Waterborne one-component polyurethane stoving top coat (Bayhydrol® E 155)

RR 6052	Two-component polyurethane top coat (Desmodur® N 3390/ Desmophen® 670)

RR 6058	Waterborne two-component polyurethane top coat (Bayhydrol® A 145/ Bayhydur® 3100/ Desmodur® N 3600)