Stannous octoate

The physical properties of polyurethane adhesives result from a special form of phase separation which occurs in the cross-linked polyurethane stmcture. The urethane portions of polyurethanes tend to separate from the polyol portion of the resin, providing good shear strength, good low temperature flexibiUty, and high peel strength. Catalysts such as dibutyltin dilaurate [77-58-7], stannous octoate [1912-83-0], l,4-diazabicyclo[2.2.2]octane... 

In recent years there has been some substitution of TDI by MDI derivatives. One-shot polyether processes became feasible with the advent of sufficiently powerful catalysts. For many years tertiary amines had been used with both polyesters and the newer polyethers. Examples included alkyl morpholines and triethylamine. Catalysts such as triethylenediamine ( Dabco ) and 4-dimethyla-minopyridine were rather more powerful but not satisfactory on their own. In the late 1950s organo-tin catalysts such as dibutyl tin dilaurate and stannous octoate were found to be powerful catalysts for the chain extension reactions. It was found that by use of varying combinations of a tin catayst with a tertiary amine... 

The most common catalyst used in urethane adhesives is a tin(lV) salt, dibutyltin dilaurate. Tin(IV) salts are known to catalyze degradation reactions at high temperatures [30J. Tin(II) salts, such as stannous octoate, are excellent urethane catalysts but can hydrolyze easily in the presence of water and deactivate. More recently, bismuth carboxylates, such as bismuth neodecanoate, have been found to be active urethane catalysts with good selectivity toward the hydroxyl/isocyanate reaction, as opposed to catalyzing the water/isocyanate reaction, which, in turn, could cause foaming in an adhesive bond line [31]. 

Place Arcol Polyol F-3022 (100 g, 0.1 eq., 56 OH, mixed PO/EO triol from Bayer) into a suitable container. To this add distilled water (3.3 g, 0.4125 eq.), Niax Silicone L-620 (0.5 g, a silicone surfactant from OSi Specialties), and Niax C-183 (0.12 g, an amine catalyst from OSi Specialties). Thoroughly blend this mixture without incorporating air bubbles. Then add Dabco T-9 (0.25 g, stannous octoate from Air Products) and mix again. The T-9 must be added last because it is quite water sensitive, so its exposure to the water-containing polyol blend should be kept to a minimum. To this polyol blend, quickly add Mondur TD-80 (42.6 g, 0.4868 eq., a mixture of 80% 2,4-TDI and 20% 2,6-TDI isomers from Bayer) and immediately stir at 3000 rpm for 5 s. Quickly pour the reaction mixture into a suitable container such as a 1-qt paper or plastic cup and allow the foam to free-rise. The stir blade may be wiped or brushed clean. 

Multiblock polyethylene-polydimethylsiloxane copolymers were obtained by the reaction of silane terminated PDMS and hydroxyl terminated polyethylene oligomers in the presence of stannous octoate as the catalyst 254). The reactions were conducted in refluxing xylene for 24 hours. PDMS block size was kept constant at 3,200 g/mole, whereas polyethylene segment molecular weights were varied between 1,200 and 6,500 g/mole. Thermal analysis and dynamic mechanical studies of the copolymers showed the formation of two-phase structures with crystalline polyethylene segments. 

Preparation and characteristics of ABA type polycaprolactone-b-polydimethyl-siloxane block copolymers have been recently reported 289). In this study, ring-opening polymerization of e-caprolactone was achieved in melt, using a hydroxybutyl terminated PSX as the initiator and a catalytic amount of stannous octoate. Reactions were completed in two steps as shown in Reaction Scheme XIX. 

Ring-opening polymerization was used to synthesize PTMC. The polymerization was carried out in evacuated and sealed glass ampoules with stannous octoate as a catalyst. The schematic reaction equations are shown in Schemes 8.7 and 8.8. The reaction time for aU homo- and copolymerizations were three days and the reaction temperature at 130 2°C. The obtained polymers were purified by dissolution in chloroform and precipitation in isopropanol. The precipitated polymers were collected, and washed with fresh isopropanol, and dried under reduced pressure at room temperamre until constant weight. 

With stannous octoate-promoted polymerization, the metal species is believed to function as the catalyst and water (added or endogenous), or alcohol, serves as the initiator (Fig. 2). This mechanism is supported by recent kinetic studies of PCL polymerization in the presence of triphenyltin acetate (46). After an induction period, polymerization is zero order with respect to monomer and near first... 

Stannous octoate has the advantage of having been used to prepare polymers (Silastic, Capronor) for which substantial toxicological data are now available (6,48). Stannous octoate-initiated polymerization has been used to prepare copolymers of e-caprolactone with other lactones, including diglycolide, dilactide, 6-valerolactone, e-decalactone, and other alkyl-substituted e-caprolactones. Conducting... 

The copolymerization parameters for copolymerization of dilactide and e-caprolactone catalyzed by stannous octoate, stannous chloride, and tetrabutyl titinate have been determined (5). 

Initiation of stannous octoate-catalyzed copolymerization of e-caprolactone with glycerol was used to prepare a series of trifunctional hydroxy-end blocked oligomers, which were then treated with hexane-1,6-diisocyanate to form elastomeric polyesterurethanes with different crosslink densities (49). Initiation of e-caprolactone polymerization with a hydroxypropyl-terminated polydimethylsiloxane in the presence of dibutyl tin dilaurate has been used to prepare a polyester-siloxane block copolymer (Fig. 4) (50). 

The preferred initiator is stannous octoate in catalytic amount [95, 96] and polymerizations occur in bulk at 110°C or in toluene. The synthesis was expanded to stars with 40 and 48 arms by means of a hyperbranched poly(2,2 -bis(hydroxymethyl)propionicacid) or classical dendrimer, respectively [97],... 

Two different mechanisms have been proposed for the ROP of (di)lactones depending on the nature of the organometalhc derivatives. Metal halides, oxides, and carboxylates would act as Lewis acid catalysts in an ROP actually initiated with a hydroxyl-containing compound, such as water, alcohol, or co-hydroxy acid the later would result more hkely from the in-situ hydrolysis of the (di)lac-tone [11]. Polymerization is assumed to proceed through an insertion mechanism, the details of which depends on the metal compound (Scheme la). The most frequently encountered Lewis acid catalyst is undoubtedly the stannous 2-ethylhexanoate, currently referred to as stannous octoate (Sn(Oct)2). On the other hand, when metal alkoxides containing free p-, d-, or f- orbitals of a favo-... 

The polymers were made according to procedures described in Ref. 15. A representative example is given here. A 1-liter round-bottom flask equipped with an overhead mechanical stirrer was flame dried under a vacuum to remove moisture from the interior surfaces of the vessel. When cool, the vacuum was released by the introduction of dry nitrogen gas. To the flask was added, in a dry nitrogen glovebox, 500.0 grams (3.469 moles) of pure L-lactide. Thai, 0.35 ml of a 0.33 molar catalyst solution (stannous octoate in toluene) containing 1.155 x 10 moles of catalyst was Current address Los Alamos National Laboratory, Los Alamos, NM 87544... 

The reactor was purged with nitrogen and heated to 50 °C under 20 torr vacuum. The vacuum was broken and 500 ppm of stannous octoate catalyst obtained from City Chemical was added. The methanol was stripped under 20 torr vacuum at 195 °C for 4-6 hours yielding a viscous light yellow natural oil polyol with an equivalent weight of 660. 

A reactor was charged with 3,6-dimethyl-l,4-dioxane-2,5-dione (8 mmol), 2-bis-(picolylamine)-ethanol (0.5 mmol), 10 ml of toluene, and 50 pi of 50% stannous octoate in toluene and then immersed into a preheated oil bath at 125°C for 3 hours. The mixture was then cooled to ambient temperature, concentrated, and the residue dissolved in 10 ml of CH2C12. The solution was then washed with 10 ml of 0.1 M HC1,10 ml saturated brine, and twice withl5 ml of water and then dried using Na2S04. The product was isolated in 72% yield after filtration and solvent removal. 

Two terpolymers of poly(L-lactide-co-glycolide) were prepared in this application that had enhanced fracture toughness by incorporating -y-caprolactone by ring-opening polymerization using either stannous octoate or stannous trifluoromethane sulfonate as the catalyst. The products synthesized by this method were ... 

A reaction kettle equipped with mechanical stirrer was placed in a glove box filled with nitrogen and heated to 120°C for 1 hour to remove moisture. The reactor was then charged with glycolide (200 g), y-caprolactone (200 g), 0.27 ml dodecanol, 700 ml of xylene, and 1.12 ml of stannous octoate and where glycolide component was added over four portions in 2-hour intervals. The mixture was then stirred at 120°C for 90 hours and the product isolated after dissolving in chloroform and precipitated in methanol. 2... 

The entire step 1 product was treated with L-lactide (170 g), glycolide (30 g), and 48 ml stannous octoate and then heated to 120°C for 70 hours. Once the... 

III) and L-lactide using stannous octoate as catalyst and then hydrogenated it... 

Catalysts Catalysts are widely used for PU manufacture. Sometimes a combination of two or three catalysts is required to obtain the desired balance of reaction rates between compounds of differing active hydrogen activity. Metal compounds, especially organotin compounds, are much more efficient catalysts than tertiary amines for the -OH/NCO reaction. In addition to more commonly used dibutyltin(IV) dilaurate, dibutyltin(IV) diacetate, dialkyltin(IV) oxide or salts of divalent fin with a variety of carboxylic acids such as stannous octoate, hexoate and naphthenate etc. are available for this purpose. Combination of tin catalysts with tertiary amines has been reported to lead to a synergistic increase in catalytic activity. 

A common way of controlling the opening of cells is the use of a gelation catalyst. Stannous octoate (SO) is one such catalyst. Figure 3.14 shows the effects of SO on air flow. This illustration is particularly appropriate since our purpose is to build a device through which fluids will pass. 

Determination of Diisocyanate Equivalents of Diols. Fifty grams of the diol, 0.017 gram of stannous octoate, and variable amounts of toluene-2,4-diisocyanate were added by syringe to 4-oz screw-capped... 

RR 110-3 60 Vorite 145 40 Stannous octoate One hour at ambient room temperature... 

RR 222-2 70 Vorite 145 30 Stannous octoate One hour at ambient toom temperature j... 

The presence of these cyclic esters in the crude polycondensation reaction product was found to be unavoidable indeed some evidence was developed that the polycondensation at least in part proceeds via these cyclic esters. Considerable effort was expended to find means for eliminating these cyclic five-membered esters from our polycondensation products. The cyclic esters can be eliminated by either inducing them to polymerize by use of Lewis acid catalysts such as stannous octoate, or by subjecting them to ring opening by means of an alcohol or water (7). 

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