Search results
Results from the WOW.Com Content Network
Moisture cured polyurethane–urea coatings have been made by reacting 1,2,3-triazole rich polyether polyols with HMDI at NCO/OH eq. ratio of 1.2 to obtain isocyanate-terminated polyurethane prepolymers. The prepolymers were cured under atmospheric moisture to make polyurethane–urea free films.
Most coatings have four basic components. These are the resin, solvent, pigment and additive systems [5] but the resin or binder is the key ingredient. Continuing environmental legislation in many countries along with geopolitics such as oil production are ensuring that chemists are increasingly turning to waterborne technology for paint/coatings and since resins or binders are the most ...
This is of particular interest in the area of polyurethane coatings, where light stability is a critical factor and is the main reason that aliphatic isocyanates are used in making polyurethane coatings. When PU foam, which is made using aromatic isocyanates, is exposed to visible light, it discolors, turning from off-white to yellow to reddish ...
Polyurethane dispersion, or PUD, is understood to be a polyurethane polymer resin dispersed in water, rather than a solvent, although some cosolvent may be used.Its manufacture involves the synthesis of polyurethanes having carboxylic acid functionality or nonionic hydrophiles like PEG (polyethylene glycol) incorporated into, or pendant from, the polymer backbone. [1]
Castor oil by itself has been used in making a variety of polyurethane products, ranging from coatings to foams, and the use of castor oil derivatives continues to be an area of active development. Castor oil derivatized with propylene oxide [9] makes polyurethane foam for mattresses and yet another new derivative is used in coatings [10]
Alkyd resins are usually classed as long oil, [11] medium oil and short oil. [12] These terms represent the oil length in the resin. [ 13 ] Alkyds are also modified with phenolic resin , styrene , vinyl toluene , acrylic monomers (to make them dry more quickly) and isocyanates to produce a polyurethane modified alkyd.
Ester-based TPU in cases where oil and grease resistance is more relevant. When stable light colour and non-yellowing performance are required, aliphatic TPU based on aliphatic isocyanates is used. BASF has pioneered crosslinking during TPU transformation, made possible by adding liquid crosslinkers or using a solid granulated additive ...
A spelling pronunciation is the pronunciation of a word according to its spelling when this differs from a longstanding standard or traditional pronunciation. Words that are spelled with letters that were never pronounced or that were not pronounced for many generations or even hundreds of years have increasingly been pronounced as written, especially since the arrival of mandatory schooling ...