Customer

Topcoats and clear coats – now self-healing possible


Topcoats and clear coats - now self-healing possible. Solventborne OEM Polyurethane. Outstanding properties regarding gloss, flow characteristics as well as high mechanical and chemical resistance contribute to the growing success of one- and two-component polyurethane systems compared to conventional thermosetting-acrylic (TSA) coatings. Today, environmentally friendly waterborne polyurethane coatings are used for automotive finishing as well. Bayer MaterialScience has developed high solids und super high solids for environmentally friendly polyurethane coating systems which meet the highest standards of the automotive industry regarding scratch and weather resistance. Bayer MaterialScience offers Bayhydrol® / Bayhydur® combinations for two-component systems, as well as Bayhydur® BL- and Bayhytherm®-grades for one-component stoving systems. Our experts will gladly assist you if you are interested in this technology.

Polyurethane coatings offer a number of inherent advantages due to their unique chemistry:
    • High reactivity and complete crosslinking even if cured at low temperatures
    • Good chemical and weather resistance
    • Hardness, mechanical resistance and elasticity due to their urethane / urea structure
    • Hydrogen-bonds allow thermoplastic flow properties and release internal stresses. Therefore they promote the "self-healing" of superficial scratches
    • Good compatibility with primers
    • High solids content / low VOC content
    • Great optical properties – High gloss or wet look
Solventborne OEM Polyurethane clear coats
A polyurethane clear coat for OEM applications is the reaction product of an isocyante with an acrylate polyol. The subsequent stoving process at 130-140°C lasts about 30 minutes, even though lower temperatures would still allow a complete reaction, so the coating is not sensitive when it comes to the strict maintenance of the stoving conditions. Polyurethane clear coats can be applied to a large variety of primers and primer surfacers. They can be formulated as high solids and low VOC coatings.

Show details for ... more on the chemistry... more on the chemistry

Product examples: poly-isocyanates for automotive clear coats:

Type
Solids
in %
% NCO
on solids
Viscosity
mPas at 23°C
Characteristics
Desmodur®
N 3390
HDI trimer
90
21.8
500
High gloss, good chemical and weather resistance, lightfast, good mechanical resistance
Desmodur®
N 3600
HDI trimer
100
23.0
1200
For High Solid coatings, high gloss, good chemicals and weather resistance, lightfast, good mechanical resistance
Desmodur®
N 3900
HDI polyisocyanate
100
23.5
730
Hardener for weather resistant coating systems. For High solid coatings for automotive refinish, large vehicle finishing and plastic coatings
Desmodur®
XP 2679
HDI
polyisocyanate
80
19.3
500
For self-healing coatings, lightfast, weather resistant, scratch resistant
Desmodur®
Z 4470
IPDI trimer
70
17.0
600
Hard, high gloss, good chemical and weather resistance, lightfast, good mechanical resistance, for combination with
Desmodur® N
Desmodur®
BL 3575/1
HDI polyisocyanate
75
14.0
bl. NCO
on solids
3600
Good chemical and weather, lightfast, very thermo-stable
Desmodur®
PL 350
HDI polyisocyanate
75
14.0
bl.NCO
on solids
4300
In combination with polyol components, suitable for lightfast stoving coating systems

Feature: Polyurethane raw material for self-healing coatings
The latest developments at Bayer MaterialScience are raw materials for self-healing coatings. This is the underlying concept: Mechanical stresses like for instance brushes in a car-wash do not cause this type of poly-isocyanate to form micro cracks. Instead it shows plastic deformation. When the coating surface is exposed to higher temperatures it generates a so-called “reflow-effect”. ... more

Waterborne two-component polyurethane clearcoats for automotive OEM coatings

Waterborne two-component polyurethane clearcoats provide an alternative to solventborne two-component polyurethane systems. The strict demands made by the automotive industry are met in nearly all respects by hardeners based on aliphatic polyisocyanates in both hydrophobic and hydrophilic form.

Show details for ... more on chemistry and technology... more on chemistry and technology
Show details for ... top coats for OEM plastic coatings... top coats for OEM plastic coatings
    Product examples, waterborne dispersions

    Type
    (Festkörper)
    % OH
    on solids
    Solids in % appr.
    pH
    Characteristics
    Bayhydrol®
    A 2601
    Polyacrylate dispersion
    3.9
    45
    7,5
    For clear- and top coats with good resistance properties and very fast drying
    Bayhydrol®
    A XP 2770
    Polyacrylate dispersion
    3.9
    44.5
    8,0
    Low VOC variant of Bayhydrol A 2470 without flash point
    Bayhydrol®
    U XP 2750
    Polyacrylate dispersion
    3.6
    43
    8,0
    Hydrophilic crosslinker in combination with HDI-based greades to enhance drying properties
    Bayhydrol®
    U XP 2757
    Polyurethane dispersion
    1.8
    52
    7.5
    Solvent-free, for plastic coatings, incl. softfeel & effect coatings, good adhesion to different plastics, good resistance to hydrolysis
    Bayhydrol®
    A 2058
    Polyester polyacrylate Hybrid dispersion
    4.8
    42
    8.5
    Flexible, low-cosolvent dispersion, good adhesion to plastics

    For more on clearcoats for plastic applications have a detailed look at these brochures and presentations:


    Polyol Products
    MS 00063643

    .
    2K WB Toolbox
    MS00063580



    .
    .Bayhydrol A
    MS00063642



    Article:Shining Prospects for two-component polyurethane clearcoats

    Presentation:"Blocked Polyisocyanates Examples of applications"


    Have a look at these related videos:

    Outdorr weathering Video: outdoor weathering tests and result evaluation
    Outdoor weathering [1:07]
    Corrosion protection and weathering tests Video: Weathering tests for corrosion protection coatings
    Accelerated weathering and corrosion protection [2:26]
    Laboratory car wash – Video: Mechanical resistance test / car wash simulation in a lab test
    Mechanical resistance test / car wash simulation in a lab test [2:04]
    Gradient oven method - Video: Resistance tests with the gradient oven
    Resistance tests with the gradient oven [1:35]

    Share this site:
    Delicious Digg Facebook Google LinkedIn Mister Wong MySpace StudiVZ Stumpleupon Twitter Yahoo