HYDROPHOBICITY WITH RENEWABLE TECHNOLOGY
Cardolite offers a line of renewable, cashew nutshell liquid (CNSL) based polyols that have unique qualities compared to widely known polyester and polyether polyols, and other natural oil based polyols. CNSL polyols and diols are very hydrophobic because of the long aliphatic chain of cardanol, and fewer ether oxygen atoms compared to typical polyether polyols (less hydrophilic). This hydrophobicity provides excellent water resistance and less moisture sensitivity during cure with isocyanate for increased durability of the final polyurethane system.
The experiment shown on this page is an attempt to quantify the relative water resistance in PU systems of different polyols and diols. When NCO reacts with water, it releases CO2. Other than in moisture cured systems, the reaction of NCO with water is undesirable, and the goal is to react the NCO only with the polyol. In this test, a mixture of polyol/NCO (Index 100) is poured over the same amount of water and the amount of CO2 released is measured. The results indicate CNSL diols and CNSL polyols are more hydrophobic than PPG diols and castor-based polyols, respectively. NX-9201 is very close to PolyBD in performance, but at lower price.
CHEMICAL RESISTANCE AND HYDROLYTIC STABILITY
Different from other renewable polyols obtained from soy and castor oil, CNSL polyols have an aromatic structure that translates into excellent thermal resistance and chemical resistance to acid and alkaline solutions. Moreover, the combination of aromaticity and long aliphatic chain delivers hydrolytic stability and mechanical strength to CNSL based polyols.
Hydrolytic stability is a key benefit offered by CNSL diols. Prepolymers based on diols from different chemistries were immersed in 3 different solutions, water, sodium hydroxide, and sulfuric acid for 21 days at RT. The hardness was measured before and after exposure and the data in the graph indicates the change in hardness. NX-9203 showed the best performance amongst all systems and NX-9201 performed similarly to PolyBD and polycarbonate diols. PPGs showed the worse hydrolytic stability.
ALTERNATIVE TO POLYBUTADIENE DIOLS
NX-9203 and NX-9203LP bring value as full or partial replacements for polybutadiene (PolyBD) diols. Similarly to PolyBD diols, NX-9203/NX-9203LP offer excellent hydrophobicity and hydrolytic stability. The good compatibility between the two types of diols enables for blends that provide even better properties than each diol by itself. Those systems show very good mechanical and bonding properties.
WIDE RANGE OF PROPERTIES AND PERFORMANCE
CNSL polyols can be designed for varied applications and functionalized to achieve a wide range of properties. Cardolite polyol product line consists of diols, and medium and high functionality polyols. CNSL diols combine the benefits of CNSL and Polyester technologies resulting in excellent solvent, alkaline, acid, and water resistance, and high physical properties such as tensile strength. CNSL diols can be formulated as is or as a building block for prepolymers. CNSL Mannich polyols have medium to high functionality and provide fast reactivity, high compression strength and improved fire and thermal resistance properties. Other medium and high functionality polyols include CNSL novolacs and specially modified polyols deliver high overall strength and hydrophobicity. Furthermore, light color CNSL polyols have been developed based on Cardolite’s new Ultra LITE process technology.
CNSL polyols are suitable for 2k ambient cured coatings and adhesives, 1k blocked or moisture cured adhesives and sealants, and rigid and flexible foam applications. The following table contains CNSL polyols and diols currently available from Cardolite.