[article]
| Titre : |
Novel products : New resins with low hydroxyl functionality provide urethane prepolymers with low viscosity and excellent storage stability |
| Type de document : |
texte imprimé |
| Auteurs : |
Herbert S. Chao, Auteur ; Nan Tian, Auteur |
| Année de publication : |
2002 |
| Article en page(s) : |
p. 26-30 |
| Langues : |
Américain (ame) |
| Catégories : |
Hydroxyle En chimie organique, un hydroxyle (ou oxhydryle) peut désigner deux entités.
Un groupement -OH, appelé aussi hydroxy, qui se rencontre en particulier dans les alcools et les phénols.
Un radical : HO^{\bullet}. Il est produit par exemple lors de réactions de dissociation de peroxydes, en présence d'ions de métaux de transition (Fe(II), Cu(I), réaction de Fenton), de chauffage ou de rayonnement.
Polybutadiène
Polyuréthanes
Stabilité au stockage
Urethanes
|
| Index. décimale : |
668.3 Adhésifs et produits semblables |
| Résumé : |
Poly bd resins with lower hydroxyl functionality than the standard R45HTLO have been developed by Sartomer Co. These products, LF-1, -2, and -3, provide urethane prepolymers with lower viscosity and better storage stability compared with those derived from the product R45HTLO of the same NCO index. Furthermore, low-functionality Poly bd resins, polyurethanes, with and without chain-extenders, were prepared via two-step and one-step syntheses, respectively. As anticipated, more thermoplastic properties were noticed for the polyurethanes derived from Poly bd resins with low-hydroxyl functionality.
Poly bd resin, a hydroxyl-terminated polybutadiene liquid, has been widely used in adhesives, sealants and electrical applications owing to its low-glass transition temperature (-75 degrees C), hydrophobicity, acid-base resistance and excellent dielectric properties. As a hydrocarbon-based polyol, Poly bd resin has been widely used in polyurethane and polyester chemistries by reacting with polyisocyanates or carboxylic acid derivatives, respectively. In contrast to polyester or polyether polyols, Poly bd resin-based thermoset resins having low surface tension can easily accommodate a large quantity of inorganic fillers and hydrocarbon plasticizers, such as bitumen and soybean oil. The fillers and plasticizers can improve mechanical properties of the products and lower cost.
Although Poly bd resin contains a predominantly linear backbone structure, it also contains a small portion of branched polymer, resulting from the radical polymerization process. Thus, the commercial product has a hydroxyl functionality of 2.4 to 2.6 per chain on average.
This branched structure occasionally imposes limitations on customers' processes or product performance especially when they seek design flexibility between thermoplastic and thermoset properties. To offer more choices and flexibility in the Poly bds, three new grades-- LF-1, -2, and -3-with lower hydroxyl functionality of 2 to 2.3 are introduced. |
| Note de contenu : |
- Gumstock properties derived from low functionality Poly bd resins
- Prepolymer viscosity from Poly bd resins with regular and low functionality
- Stability of prepolymer viscosity from Poly bd R45HTLO and LF materials
- Two-step urethane elastomer from prepolymers 2-ethyl-1,3-hexandiol
- Procedures of preparing prepolymers
- Two-step urethane elastomer from prepolymers and 2-ethyl-1,3-hexandiol. Procedures for preparing urethanes via two-steps process |
| En ligne : |
https://drive.google.com/file/d/14VsLrYsbwfgKWQWmklB6G8Tojnd1cz4y/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20029 |
in ADHESIVES AGE > Vol. 45, N° 10 (10/2002) . - p. 26-30
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