A foam article for use in a seat cushion includes an open cell, polyurethane foam material that includes a base polyol; a crosslinker; an isocyanate; a surfactant; and water, that are reacted together to produce a seat cushion having dynamic and static performance specifications that are better than the performance characteristics for a traditional, high resilient material seat experiment involving a With the use of alicyclic diisocyanates, aliphatic alcohols and dibutyltin dilaurate as well as triethylamine as a catalysts internally-blocked polyisocyanate crosslinkers which contained allophanate bonds were synthesized. With the use of alicyclic diisocyanates, aliphatic alcohols and dibutyltin dilaurate as well as triethylamine as a catalysts internally-blocked polyisocyanate crosslinkers which contained They are used extensively and are well-known for their durability, tough bonds and high peel strength. The chemical structure of those compounds were characterized by IR, 1H-NMR, and 13C-NMR spectroscopy. A kinetic and mechanistic investigation of the alcoholysis of phenyl isocyanate using 1-propanol as the alcohol was undertaken. A molecular mechanism of urethane formation in both alcohol and isocyanate excess is explored using a combination of an accurate fourth generation Gaussian thermochemistry (G4MP2) with the Solvent Model Density (SMD) implicit solvent model. During the research of self-healing polyurethane networks, we have studied the terminal functionalization of hydroxyl-terminated polybutadiene with furfuryl isocyanate and occasionally obtained the furan-terminated polybutadiene allophanate. Crosslinking of polyurethanes by a reaction of isocyanate groups with urethane groups leading to trifunctional allophanate branch points is treated statistically using This means that a PU paint may contain urethane, urea, allophanate and biuret linkages.. temperature, type and amount of catalyst) which may for example be favourable for the formation of allophanate structures. Gel fraction and equilibrium elastic modulus of networks formed from , -dihydroxypoly(oxypropylene) and bis(4-isocyanatophenyl)methane (MDI) as a result of side reactions were compared with theoretical predictions based on the theory of branching processes (Macromolecules, 23, 1774 (1990)). The determination of allophanate and biuret has been of great interest. the allophanate The present invention relates to polyisocyanate mixtures which are reaction products of 4,4'-diphenylmethane diisocyanate as the isocyanate component, are liquid at greater than 5C and have an nco content of 14.5 to 24% by weight and an allophanate group content (calculated as C 2 HN 2 O 3, molecular weight = 101) of 7.7 to 14.5% by weight; a process for the production of The gradual increase of polyurethane tensile properties upon cooling over a period of days is sometimes considered a result of slow formation of allophanates (among other possibilities These prepolymers allophanate modified (cyclo)aliphatic polyisocyanates can also be used as component (A) according to the present invention. Disclosed is an allophanate group-containing polyisocyanate composition (C) including a reaction product of diphenylmethane diisocyanate (A) and a hydroxyl group-containing compound (B), wherein the hydroxyl group-containing These The stability of polyurethane elastomers based on different building blocks of macrodiols (polyester, polyether, polycarbonate, polybutadiene, and polyisobutylene), isocyanates (aromatic and aliphatic), and chain extenders (diols, triols, and diamines) are summarised, and the mechanisms of different types of degradation are presented. Polyurethane resin compositions include a urethane prepolymer with an active hydrogen group and a polyisocyanate, or a urethane prepolymer with an isocyanate group and an active hydrogen compound. The present invention relates to a process for lowering the viscosity of compositions containing compounds having urethane groups, in which all or some of the urethane groups contained therein are reacted with monoisocyanates to form allophanate groups. The most bizarre term in all of polymer chemistry, and probably organic chemistry as well is that awful word from polyurethane chemistry that sticks to your tongue and leaves Polyurethanes contain urea, allophanate, biuret groups, and aromatic rings in addition to urethane groups. These groups affect the properties of the resultant polymer. The reactions between a diisocyanate, a linear long-chain dial, and a low-molecular-weight chain extender lead to the production of elastomers. The present invention also relates to compounds having allophanate groups and compositions containing such Allophanate is usually regarded as a side product during the preparation of polyurethanes. Kogon , , followed the disappearance of the absorption band in the near infrared to study the formation 10 Two very common polyols are hydroxyl-terminated polypropylene oxide (PPO) and polytetramethylene oxide (PTMO). The invention relates to a method for the continuous production of allophanate-containing polyurethane prepolymers which have an increased functionality and can be cured using actinic radiation. allophanate urethane acrylates Prior art date 2009-09-05 Application number PCT/EP2010/005144 Other languages German (de) French (fr) The polyurethane material itself is a polar polymer with the SFE value exceeding 50 kJ/m 2 in many cases which makes it biodegradable and completely immiscible in practice with polyolefins, (i.e. functionality and consequently reduces the crosslink density of the cured polyurethane product. The NMR The experimental sol fraction can be correlated with theoretical predictions. The properties of a polyurethane depend to a larger degree on the type, molecular weight and hydroxyl number of the polyol. 1.. IntroductionPolyurethane networks based on hydroxyl terminated polybutadiene (HTPB) are widely used in composite solid propellants, explosives, adhesives, sealants, liners The allophanate link in polyurethane synthesis @article{Arshady1990TheAL, title={The allophanate link in polyurethane synthesis}, author={Reza Arshady and Maurice H. George}, The stability of allophanate depends on the type of structure and on temperature. by degrading the allophanate and the biuret linkages with aliphatic primary amine. The present invention relates to ethylenically unsaturated polyurethanes which are substantially free from isocyanate groups and havea) a total content of (meth)acryloyl groups (calculated as C=C, MW 24) of 1 to 20% by weight.b) an allophanate group content (calculated as N.sub.2 C.sub.2 HO.sub.3, MW 101) of 1 to 20% by weight andc) an isocyanurate group content Although silicone-based polyurethanes have demonstrated increased oxidative stability, there have been conflicting reports of the long-term hydrolytic stability of Optim and PurSil() 35 based on recent temperature-accelerated hydrolysis Polyurethane is a versatile polymeric material that can be tailored to meet the demands of a number of adhesive and sealant systems. 1. 1.. IntroductionPolyurethane networks based on hydroxyl terminated polybutadiene (HTPB) are widely used in composite solid propellants, explosives, adhesives, sealants, liners and coating materials , , .A favourable feature associated with polyurethane network systems is the ease with which the end properties can be tailored with good control by mere adjustment in the Polyurethane is widely used, with its two major applications, soft furnishings and insulation, having low thermal inertia, and hence enhanced flammability. Hydrophilic hardener compositions include at least one hydrophobic polyisocyanate, the hydrophobic polyisocyanate containing one or more allophanate functional groups, and the allophanate functional groups being present in the hardener compositions in an amount at least equal to 6 mol % relative to the total number of moles of isocyanate monomers converted in However, like the urethane bond, at temperatures above 100-150 C, the allophanate linkage will revert to the urethane and the free isocyanate reflecting the stability of the parent urethane [56]. It is seemingly inevitable that allophanates form in the practice of making urethanes. Hier sind smtliche aktuell verfgbaren Chemikalien der CSC JKLECHEMIE einfach durchsuchbar und samt Basisdaten schnell einzusehen und einfach sortierbar. Shape memory polyurethanes were polymerized The effect of allophanate crosslinking according to the NCO/OH molar ratio on the shape memory properties of polyurethane was investigated. Their molecular weight distribution An allophanate group-containing polyisocyanate composition that contributes to the formation of a polyurethane resin with fewer bubbles is provided. What is claimed is: 1. Field of the Invention The present invention relates to a process for the preparation of low viscosity If isocyanate is in excess, trifunctional allophanate and biuret groups are formed. Polyurethane coatings are originally defined as products made from polyisocyanates and polyols, but one can also define them more broadly and include all the systems based on a polyisocyanate whether the reaction is with a polyol, polyamine or water. hydrophilic polyurethane urea solutionshydrophilic polyurethane urea solutions .. .. In addition to their flammability, polyurethanes form carbon monoxide, hydrogen cyanide and other toxic products on decomposition and combustion. Depending on the nature of the isocyanate that reacts with the urethane, two different allophanates can be expected ( Fig. 11 ). Each allophanate function contains two carbonyl groups, one coming from the initial urethane function, and the other coming from the isocyanate function. The resulting networks The method of obtaining these A one-component polyurethane adhesive comprises a polyurethane precursor prepared by reaction of (a) a polyisocyanate component containing one or more polyisocyanate compounds (a-1) each having at least one uretdione group and optionally one or more polyisocyanates (a-2) each having two or more isocyanate groups with an active hydrogen compound (b) having a Polyurethane resin compositions include a urethane prepolymer with an active hydrogen group and a polyisocyanate, or a urethane prepolymer w Toggle navigation. Their Inventive allophanate-containing binders were tested with the allophanate-containing binders of the comparative examples for suitability in electron-beam-curing coil-coating topcoat materials. Allophanate can dissociate, ending to the reformation of urethane and isocyanate. Abstract. If isocyanate is in excess, trifunctional allophanate and Polyurethane resin compositions include a urethane prepolymer with an active hydrogen group and a polyisocyanate, or a urethane prepolymer w Toggle navigation. Polyurethanes prepared by reaction of 4,4-diphenylmethane diisocyanate with poly (ethylene adipate) were crosslinked with allophanate and isocyanurate groups. However, reduced crosslink density leads to lower UV reactivity and less robust coating properties.2 The functionality of UV curing polyurethane resins can be adjusted by adding a double bond bearing alcohol to the allophanate reaction. Process for Preparing Allophanate-Containing Actinically Curable Polyurethane Prepolymers with Increased Resistance 7700662 - 11731592 - USPTO Application Mar 30, 2007 - Publication Apr 20, 2010 Allophanate, which in this study was isolated and characterized, An in-depth exploratory study on the mechanism of isocyanurate formation during the assembly of rigid PU/PIR polyurethane foams was performed thereby unravelling the role and working principle of the catalyst. The chemistry of polyurethane foams and their thermal An alkoxysilane-functional polyurethane containing allophanate and/or biuret groups wherein at least 10 mol % of the allophanate and/or biuret groups are formed The urethane prepolymers having an active hydrogen group or an isocyanate group are obtained by reacting an allophanate group-containing polyisocyanate with a side-chain Abstract. When aliphatic polyesters are used in polyols to make polyurethane, however, the NH groups provide electropositive hydrogen to act as electron acceptors; the resulting hydrogen bonding in polyester urethanes makes them the optimum choice for high-strength elastomers. The polyurethane elastomer cured with glycol or diamine was made soluble into DMSO, DMA etc.
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