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Solventborne polyurethane coatings – A proven solution for high quality furniture coatings

Clear furniture coatings based on aromatic polyisocyanates have a long tradition. Also for the coating layers below the topcoats polyurethanes provide a number of good properties like fast drying and good sanding behavior. Bayer MaterialScience offers a large number of coating raw materials for wood coatings that meet the most demanding requirements for this application.

Some products and starting formulations for furniture coatings and interior joinery:

	Type	Solids in %	Viscosity mPas at 23°C	% NCO or OH on solids	Characteristics
Desmodur® L 75	Aromatic polyisocyanate	51	1600	17.7 NCO	Standard binder for a large application range
Desmodur® IL 1351	Aromatic polyisocyanate	51	1600	15.6 NCO	Very fast drying, quick sandability
Desmodur® IL 1451	Aromatic polyisocyanate	51	250	14.5 NCO	Quick drying, early sandability, improved compatibility
Desmophen® 1300 X	Polyester polyol	75	3450	4.3 OH	Universal binder, medium elasticity
Desmophen® PL 817	Polyester polyol	75	10000	4.4 OH	For very hard coatings with good matting properties

Some suitable starting formulations:

RR 6608	Sprayable primer (Desmophen® 1300 X, Desmodur® IL / Desmodur® L 75)

RR 6616	Sprayable clearcoat with silky gloss (Desmophen® 1300 X, Desmodur® IL 1351 /Desmodur® L 75)

RR 6677	Sprayable primer with good balance between drying speed, surface properties and price (Desmophen® PL 817 / Desmodur® L 75 / IL 1351)

RR 6627	Sprayable high-gloss clearcoat (Desmophen® 1300 X / Desmophen® RD 181 / Desmodur® IL/L 75)

UV-stable two-component polyurethane raw materials for interior joinery and furniture coatings
For fast drying, non yellowing coatings hydroxy-functional polyacrylates (like Desmophen® A by Viverso) combined with Desmodur® N type polyisocyanates offer a high quality solution for primers as well as for topcoats. Non yellowing resins are mainly used when pigmented coatings are applied.

Some products and starting formulations for furniture and interior joinery:

	Type	Solids in %	Viscosity mPas at 23°C	% NCO on solids	Characteristics
Desmodur® N 75 MPA/X	HDI-biuret	75	250	22.0	For lightfast coatings with good chemical and weather resistance, very good gloss retention, extremly good mechanical properties
Desmodur® HL BA	TDI/HDI polyisocyanat	60	2200	17.5	Very fast drying, low yellowing

Two starting formulations for UV-stable polyurethane wood coatings

RR 6621	Sprayable clear-coating, semi-gloss primer or topcoat application (Desmodur® N 75)

RR 6652	Sprayable white semi-gloss topcoat for open pore effect (Desmodur® N 75)

UV-stable two-component polyurethane raw materials for exterior joinery coatings
If wood is used for exterior joinery, it needs to be protected from the elements to maintain its integrity and good appearance. This can best be achieved by pigmented coatings. Polyurethane based coatings have a property profile that suits this application in an ideal way.

Polyurethane raw materials for exterior joinery (examples)

	Type	Solids in %	Viscosity mPas at 23°C	% NCO or OH on solids	Characteristics
Desmophen® 651 MPA/X	Branched hydrroxy-containing Polyester	67	25000	8.2 OH	Very good gloss retention, good chemical and weather resistance and outstanding mechanical properties
Desmodur® N 75 BA	HDI-Biuret	75	160	22.0 NCO	For lightfast coatings with good chemical and weather resistance, very good gloss and outstanding mechanical properties

A suitable starting formutlation

RR 6665

Sprayable, weather resistant, white high-gloss topcoat
(Desmophen® 651 / Desmophen® RD 181 / Desmodur® N 75)

Highlight: Desmodur® E XP 2605 - One-component moisture curing – Fast as nitrocellulose but with polyurethane quality
Polyurethane and nitrocellulose coatings are the most popular systems used for wood coatings worldwide. Polyurethane coatings offer a very high performance, while nitrocellulose coatings are drying very fast. In order to offer the best out of both technologies, Bayer MaterialScience introduced Desmodur® E XP 2605. It brings together the fast curing properties of NC and the performance profile of polyurethanes. On top of this, Desmodur® E XP 2605 does not have the VOC issues commonly associated with NC. Being a moisture curing prepolymer, it can be applied as a 1K system, yet offers excellent chemical and mechanical resistance.

Get more information on this product in this presentation.

Starting formulations:

RR 6669	Primer (Desmodur® E XP 2605)

RR 6670	Glossy topcoat (Desmodur® E XP 2605)

RR 6671	Topcoat with silky gloss (Desmodur® E XP 2605)

RR 6672	Topcoat with silky gloss and primer (Desmodur® E XP 2605)