Customer

Polyurethane top coats for commercial vehicles – extremely resistant in every climate


Outstanding mechanical properties in extreme weather conditions have made two-component polyurethane systems the top coats of choice for commercial vehicles. They are resistant against harsh weather conditions, dust, dirt, aggressive chemicals and solvents. Their optical appearance remains as good as new even after years. Polyurethane systems show their performance in demanding applications like aircraft coating, where an extreme UV- and temperature resistance are essential.

For the production of high solid systems and waterborne coatings Bayer MaterialScience provides polyurethane raw materials like polyol dispersions, low-viscosity and hydrophilized polyisocyanates for waterborne systems, polyester polyols as well as polyisocyanate hardeners.


Some polyurethane raw materials for commercial vehicle top coats:

Waterborne two-component systems

Polyacrylate / Polyurethane 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 properties, high shear stability for high-gloss topcoats with good adhesion and resistance to solvents and water
Bayhydrol®
A 2470
Polyacrylate
dispersion
45
3.9
2000
For clear- and top coats with good resistance properties
Bayhydrol®
A 2601
Polyacrylate
dispersion
44.5
3.9
2000
For clearcoats and topcoats with good resistance properties and very rapid drying without adverse effect on pot life
Bayhydrol®
A 2695
Polyacrylate
dispersion
45
5.0
2500
For clear- and top coats with very good resistance properties (anti graffiti properties)
Bayhydrol®
A XP 2770
Polyacrylate
dispersion
45
3.9
2000
Low-VOC variant of Bayhydrol A 2470 without flash point
Bayhydrol®
A 2809 XP
Polyacrylate
dispersion
47
3.3
1300
low VOC, high gloss, good chemical resistance, good adhesion on different substrates
Bayhydrol®
UH XP 2592
Polyester
polyacrylate
dispersion
45
2.1
300
For waterborne air- and force-drying, high-gloss coatings offering a high degree of corrosion protection
Bayhydrol®
U XP 2750
Polyurethane
dispersion
43
3.6
1000
For clearcoats and topcoats with outstanding weathering resistance properties
Bayhydrol®
U XP 2766
Polyurethane
dispersion
40
4.0
3000
For clearcoats and topcoats with very high gloss and high hardness, ideal for mixing with other dispersions to increase gloss, free of co-solvent

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 component, also as an additive for high-grade waterborne coatings
Bayhydur®
304
HDI polyisocyanate
100
18.2
4000
Hardener component, also as an additive for high-grade 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 resistance
Bayhydur®
XP 2759
IPDI polyisocyanate
70
11.0
6500
Hydrophilic crosslinking partner in combination with HDI grades for improving drying behavior
Desmodur®
N 3600
HDI trimer
100
23.0
1200
For waterborne two-component and high-solids coatings gloss, chemical and weathering resistance, good lightfastness 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
Desmodur®
N 3900
HDI trimer
100
23.5
730
For waterborne two-component and high-solids coatings that can be easily incorporated, with high gloss, chemical and weathering resistance, good lightfastness and high mechanical stability

Some starting formulations:


STIT 2421/1

Waterborne 2K PUR topcoat, glossy (Bayhydrol® A 2695 / Bayhydrol® U XP 2766 /
Desmodur® N 3900)




STIT 2539

Waterborne 2K PUR clearcoat, selfhealing (Bayhydrol® U XP 2750 / Bayhydrol® A 2601 /
Bayhydur® XP 2655




STIT 2159/2

Waterborne 2K PUR topcoat, glossy (Bayhydrol® A 2470 / Desmodur® N 3900)




STIT 2283/2

Waterborne 2K PUR topcoat, white (Bayhydrol® A XP 2770 / Bayhydur® 304)




STIT 2405/1

Waterborne 2K PUR topcoat, glossy (Bayhydrol® A 2470 / Bayhydur® 304)




STIT 2422/1

Waterborne 2K PUR topcoat, glossy (Bayhydrol® A 2470 / Bayhydur® XP 2487/1)




STIT 2625/2

Waterborne 2K PUR topcoat, glossy (Bayhydrol® U XP 2766 / Bayhydur® 304 /
Bayhydur® XP 2759)


Solventborne two-component-systems

Type
Solids in %
% NCO or OH
on solids
Viscosity
mPas at 23°C
Characteristics
Desmophen®
650 MPA
Polyester polyol
65
8.2 OH
20 000
In combination with Desmodur® N 75 MPA for coatings with outstanding UV resistance, gloss, weather resistance, good chemical and abrasion resistance
Desmophen®
651 MPA
Polyester polyol
65
8.5 OH
14 500
In combination with Desmodur® N 75 MPA or N 3390 BA for coatings with outstanding UV resistance, gloss, weather resistance, good chemical and abrasion resistance
Desmophen®
670
Polyester polyol
100
4.3 OH
2200
In combination with Desmodur® N 75 MPA or N 3390 BA for highly weather resistant films, which remain elastic at low temperatures
Desmophen®
680 X
Polyester polyol
60
3.0 OH
2750
High gloss, good chemical and weather resistance, lightfast, good mechanical resistance
Desmodur®
N 3300
HDI-trimer
100
21.8 NCO
3000
For high solid coatings, high gloss, good chemical and weather resistance, lightfast, good mechanical resistance
Desmodur®
N 3400
HDI-trimer
100
21.8 NCO
150
For high solid coatings, high gloss, good chemical and weather resistance, lightfast, good mechanical resistance
Desmodur®
N 3600
HDI-trimer
100
23.0 NCO
1200
For high solid coatings, high gloss, good chemical and weather resistance, lightfast, good mechanical resistance
Desmodur®
N 3800
HDI-trimer
100
11.0 NCO
6000
Hardener component for weather resistant coating systems, for High Solids coatings
Desmodur®
N 3390 BA/SN
HDI-isocyanurate
90
21.8 NCO
550
High gloss, high chemical and weather resistance, lightfast, good mechanical resistance
Desmodur®
Z 4470 BA
IPDI-trimer
70
17.0 NCO
600
Hard, high gloss, chemical resistance and weather resistance, lightfast, good mechanical resistance, in combination with Desmodur® N grades
Desmodur®
N 75 MPA
HDI-biuret
75
22.0 NCO
250
Good chemical resistance and weather resistance, very high gloss and outstanding mechanical properties

Suitable combination partners are polyols like hydroxy polyacrylates.

Some starting formulations


RR 4572

Two-component polyurethane top coat (Desmodur® N 75 / Desmophen® 650/ Desmophen® 651)




RR 4505

Two-component polyurethane clear coat (Desmodur® N 75 / Desmophen® 650/ Desmophen® 651)



Solvent-reduced "Very High Solid" systems with polyaspartics

The lowest possible solvent content, or rather a maximum solid content can be achieved with a combination of reactive thinners and low-viscosity polyisocyanates (polyaspartates) plus a polyol. These "Very high solid" systems contain less than 250g/l of solvent.


Type (Solids)
Reactivity
Equivalent Weight
Viscosity
mPas at 23°C
Characteristics
Desmophen®
NH 1521
Polyaspartate (90%)
+
356
150
For top coats and clear coats, in combination with Desmophen NH 1420
Desmophen®
NH 1520
Polyaspartate (100%)
+
290
1600
(bei 25°)
For top coats and clear coats, in combination with Desmophen NH 1420
Desmophen®
NH 1420
Polyaspartate (100%)
++
279
1500
(bei 15°)
For clear coats and fillers, in combination with Desmophen NH 1521
Desmophen®
NH 1220
Polyaspartate (100%)
++++
230
< 100
(bei 25°)
For putties and elastomers, in combination with Desmophen NH 1420
+ low reactivity ++++ high reactivity

Starting formulations for Very High Solid Systeme are available on Polyaspartics or by request.

For more in-depth information have a look at these brochures:

Polyol Products
MS 00063643

.
2K WB Toolbox
MS00063580



.
.Bayhydrol A
MS00063642



.
Polyaspartics
MS00051641

Brochure: Polyaspartics

Presentation: "Metal substrates - Still a challenge for radiation-curing systems?"
    Presentation: "Polyaspartics for protective coatings"

    One-Pager: Bayhydrol A 2695

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