Spotlight on CAPA 4101

Perstorp CAPA 4101 is part of a range of aliphatic polyester polyols that can be used for a wide range of polyurethane applications.  The CAPA range of polycaprolactones are low viscosity, solvent-free polyols that have excellent hydrolysis resistance and excellent mechanical properties.  CAPA 4101 is tetrafunctional (functionality of 4.0), has an OH value of  218 mg KOH/g (6.8% OHV) and an equivalent weight of 250.
Perstorp CAPA 4101
CAPA 4101
  • Lowers VOC
  • Improves impact resistance.
  • Improves abrasion resistance
  • Improves chemical resistance.

Formulation Approach

Perstorp and TRiiSO suggest starting with a high performance acrylic polyol system, add increasing weight percent of CAPA 4101, and then add required solvent to reach spray viscosity.
Starting Point Formulation Example
  Supplier Grind Part
SM2810/75  Allnex  35.68
Butyl Acetate    30.50
TiPure R960  Chemours  18.38
Everstab 328  Everspring    0.32
Everstab LS-292  Everspring    0.32
DynoAdd F1  Dynoadd    0.54
Addocat 201 (cut 10% in Butyl Acetate)  Lanxess    0.54
Incozol 2  Incorez    2.16
Totals    88.44
 Let down   Reference 0% 1.54% w/w
CAPA 4101
3.85% w/w
CAPA 4101
7.70% w/w
CAPA 4101 
11.6% w/w
CAPA 4101
  Supplier Parts Parts Parts Parts Parts
Additional 2810/75 Allnex 11.56 10.02 7.71 3.86 0
CAPA 4101 Perstorp 0 1.54 3.85 7.7 11.56
Total Parts Part A   100 100 100 100 100
Tolonate HDT LV2  Vencorez 21.8 22.37 23.26 24.72 26.19
NCO/OH   1.05 1.05 1.05 1.05 1.05
Total Weight   121.8 122.37 123.26 124.72 126.19
*Spray viscosity of 100 cps

CAPA 4101 has a minimal impact on potlife at lower concentrations:

CAPA 4101 Impact on Pot Life

VOC levels of the final coatings are decreased with the addition of CAPA 4101 as a result of higher solids content.

CAPA 4101 impact on VOCs

With regards to appearance, CAPA 4101 increased gloss, increased pencil hardness, and reduce Konig hardness.
CAPA 4101 impact on Gloss

CAPA 4101 provides a significant increase in impact resistance with and without primer, even at lower temperatures.  

CAPA 4101and Impact Resistance CAPA 4101 and Impact Resistance at Low Temperature

Abrasion resistance is improved with increased concentration of CAPA 4101.
CAPA 4101 and Abrasion Resistance

  • CS17 wheels/ 1000 gram weight/ 1000 cycles
  • Panels primed and coated with #52 rod topcoat deposition
  • Sample Panels conditioned 24 hours in dessicator prior to abrasion testing
  • MG loss results recorded immediately after test completion and after 24 hours reconditioning in dessicator
  • Each system run in duplicate

Although the chemical resistance of the initial acrylic polyol formulation was good, the addtion of CAPA 4101 yielded an incremental improvement in performance.  Specifically, a primed panel exposed to 300 MEK double rubs had no impact on gloss for formulations containing 3.85%, 7.70%, and 11.50% CAPA 4101.  The formulation containing 1.54% CAPA 4101 had slight mar with slight degloss and the reference formulation mars with degloss.
12 Hour Exposure - Chemical Resistance
  Reference 0%  1.54%
CAPA 4101
CAPA 4101
CAPA 4101
CAPA 4101
Glacial Acetic Acid Destroyed Destroyed Destroyed Destroyed Destroyed
Skydrol LD-4 Slight mark Slight mark Slight mark Slight mark Slight mark
Purell Hand Cleaner No effect No effect No effect No effect No effect
60:40 Gasoline/Toluene mix Slight mark Slight mark Slight mark Slight mark Slight mark
De-icer (MeOH/Ethylene glycol mix) Slight mark No effect No effect No effect No effect
Synthetic Brake Fluid Degloss Slight degloss Slight degloss Slight degloss Slight degloss
Automatic Transmission Fluid No effect No effect No effect No effect No effect
Synthetic Gear Oil (grade ISO 460) Slight Degloss Slight Mark No effect Slight mark Slight mark

Conclusions and Summary:
  • CAPA 4101 is a banched aliphatic polyester polyol
  • Reactive Diluent and Resin Modifier
  • Functionality 4.0
    • Reduces solvent demand
    • Improves impact resistance
    • Improves abrasion resistance
    • Improves chemical resistance
  • TRiiSO and Perstorp recommend starting with a concentration of 2-4% CAPA 4101 to optimize coating properties

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