CNSL Polyols and Diols as Replacement for Palm Oil Polyols
Cashew Nutshell Liquid (CNSL) derived diols and polyols are excellent alternatives to palm oil polyols in applications such as flexible and rigid foams. CNSL is an annually renewable oil extracted from the honeycomb structure of the cashew nut that can be used to synthesize Natural Oil Polyols (NOPs). Differently from vegetable oils like palm oil, CNSL does not interfere with the food chain and is considered a by-product of the cashew industry.
CNSL Diols as Replacement for Palm Oil Polyols in Foams
CNSL based diols show different properties than palm oil derived polyols. For instance, CNSL diols usually improve fire resistance properties of foams due to the aromatic rings in their backbone. On the contrary, palm oil polyols tend to hurt fire protection as it can be concluded from results of a flexible foam evaluation study shown here, where CNSL diols NX-9201 and NX-9203 and a palm oil polyol have been compared without any modification to the additives load and isocyanate index. Moreover, CNSL diols minimize property change due to exposure to water given their hydrophobic nature. As an example, in the same study foams based on NX-9201 and NX-9203 showed less change in compression strength than palm oil based foams after immersion in distilled water for 7 days at 50°C.
CNSL derived diols are also suitable choices for rigid foams as indicated by results of tests performed on a pour-in-place rigid foam formulation shared here. Compared to palm oil polyols, CNSL diol NX-9203 showed faster reactivity and higher mechanical properties at comparable densities. Less catalyst was used in the NX-9203 based formulation (potential cost benefits), but the same isocyanate index was used for both formulations.
For more information on CNSL diols, please consult your sales representative or reach us by submitting an inquiry on our site.
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
Cardolite renewable 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.
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. All of Cardolite diols showed good performance compared to industry benchmarks such as aliphatic polycarbonate diol, PolyBD (MW 4000 Da) and PPG type diols. NX-9208 delivered the best overall performance followed by NX-9203, NX-9207, NX-9212 and NX-9201.
NX-9212: NEW LIGHT COLOR, LOW VISCOSITY DIOL
Cardolite is pleased to launch a new CNSL-based, polyether diol called NX-9212, that offers very low viscosity (350-550cps), light Gardner color (<=5) and excellent properties. Similar to other CNSL polyols, NX-9212 demonstrated good compatibility with various polyurethane ingredients including other diols such as polybutadiene diol (up to 50% blends). NX-9212 is suitable for prepolymer making showing excellent stability in prepolymers prepared with aliphatic and aromatic isocyanates. Polyurethanes based on NX-9212 provide very good hydrolytic stability, low moisture sensitivity, and high elongation. All these properties combined make NX-9212 a great option for use in 1K polyurethanes, TPU, PUD, and other applications. This diol may also be formulated as co-binder in 2K polyurethanes.
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.