TRiiSO distributes a wide range of polyether triols that allow formulators to produce high quality polyurethane adhesives. Polyols contain reactive hydroxyl (OH) groups which react with isocyanate (NCO) groups on isocyanates to form polyurethane adhesives.
Polyether-based polyurethane adhesives exhibit enhanced hydrolytic stability and excellent resistance to weak acids and bases compared to polyester-based polyurethane adhesives. However, polyether-based polyurethane adhesives are more susceptible to UV radiation and provide poor resistance to oils and fuels compared to polyester-based polyurethane adhesives.
Polyether triols are formed by propoxylating an initiator (addition of propylene oxide to an initiator). In some cases, the initiator is ethoxylated (addition of ethylene oxide) as well as propoxylated. Ethoxylation can be incorporated in the middle of the polyol, or at the end (tip) of the triol. When polyether triols have ethylene oxide tips, the resulting hydroxyl groups are primary hydroxyls; propylene oxide tips yield secondary hydroxyl groups. Secondary hydroxyl groups react slower than primary hydroxyl groups as a result of the increased steric hindrance. Ethylene oxide is more hydrophilic, and thus polyether polyols with ethylene content tend to produce polyurethane adhesives that are more hydrophilic than those produced with polyether polyols that are made solely with propylene oxide. The initiator used to produce the triol can impact reactivity as well as functionality of the polyol. Amine initiated polyether diols are self-catalyzing and react faster than standard glycol inititated polyether triols.
There are several key characteristics which define what performance properties a given polyether triol will impart in a given polyurethane adhesive. These characteristics include: the hydroxyl number or hydroxyl value (OH value), OH equivalent weight, and the molecular weight of the triol.
Hydroxyl number (OH ) is the measure of the hydroxyl group content of gram of triol. Hydroxyl value is measured by titrating a known mass of triol against potassium hydroxide (KOH), and is expressed as mg KOH/g. Lower hydroxyl values indicates lower hydroxyl content and a higher molecular weight for the overall triol.
OH equivalent weight is the number of grams of a given product that contains one equivalent of hydroxyl groups (NCO). Equivalent weight = 56100/OH
Molecular Weight is determined by multiplying the equivalent weight by the triol functionality (3).
Your TRiiSO Technical Sales Representative is available to assist you in the selection of the appropriate polyether triol that will provide the specific properties you are trying to obtain. Click here to request a quote.