Focus on CAPA 4101
The CAPA range of polycaprolactones are low viscosity, solvent-free polyols that have excellent hydrolysis resistance and excellent mechanical properties. Chemically speaking, CAPA polyols are essentially glycol adipate polyester polyols. However, the manner in which the CAPA polyols are made result in significantly enhanced properties. Specifically, CAPA polycaprolactones are synthesized via an ring opening addition polymerization process, which results in a narrow polydispersity or molecular weight distribution. The narrow molecular weight distribution is responsible for reduced viscosities and improved mechanical properties (particularly at extreme temperatures). The addition polymerization process eliminates the acid catalysts used to produce conventional polyester polyols, resulting in ultra-low acid values and ehanced hydrolytic stability.
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. CAPA 4101's high functionality combined with the low molecular weight distribution and enhanced hydrolytic stability provides a powerful tool in a polyurethane coating formulator's toolbox.
- Lowers VOC
- Improves impact resistance.
- Improves abrasion resistance
- Improves chemical resistance.
Ingevity 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.
|Endacat 201 (cut 10% in Butyl Acetate)||TRiiSO||0.54|
|Let down||Reference 0%||1.54% w/w
|Total Parts Part A||100||100||100||100||100|
|Tolonate HDT LV2||Vencorex||21.8||22.37||23.26||24.72||26.19|
*Spray viscosity of 100 cps
CAPA 4101 has a minimal impact on potlife at lower concentrations, and VOC levels of the final coatings are decreased with the addition of CAPA 4101 as a result of higher solids content.:
With regards to appearance, CAPA 4101 increases gloss, increases pencil hardness, and reduces Konig hardness.
|Pencil Hardness #52 Rod on Un-primed Q-panels|
|% CAPA 4101||0%||1.54%||3.85%||7.70%||11.50%|
(173 gram standard weight applied to stylus with pencil; Tested in duplicate)
CAPA 4101 provides a significant increase in impact resistance with and without primer, even at lower temperatures.
Abrasion resistance is improved with increased concentration of CAPA 4101.
- 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.
|Reference 0%|| 1.54%
|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 Ingevity recommend starting with a concentration of 2-4% CAPA 4101 to optimize coating properties
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