Dibutyltin dilaureate

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... 

Following this work, the y -12F-diol was used for the direct reaction with hexamethylene-1,6-diisocyanate in the presence of dibutyltin dilaurate to produce a cross-linked elastomer or a reactive prepolymer which was terminated with either isocyanate or hydroxyl groups, depending on which reactant was in excess (142,143). 

Condensation cure can also be carried out ia emulsions (200—209). In this case, the cross-linker and polydimethylsiloxanediol are emulsified usiag anionic, cationic, or nonionic surfactants ia water, and a condensation catalyst such as dibutyltin dilaurate is added. The polymer can then undergo cross-linking, forming a continuous film when the water is evaporated. 

Other. Dibutyltin dilaurate [77-58-7] has been successfully used for many years as a coccidiostat in the treatment of intestinal worm infections in chickens and turkeys (see Antiparasitic agents). 

In the presence of the organic siHcate, the heavy-metal salts trigger the chain extension and cross-linking reactions that lead to siHcone mbber and volatile ethanol as a byproduct. Useful metal soaps iaclude stannous octanoate [1912-83-0], ziac octanoate [557-09-5], dibutyltin dilaurate [77-58-7], and dibutyltin diacetate [1067-33-0]. The reactivity of the different salts varies considerably. Stannous octanoate effects a cure ia 0.5—2 min ziac octanoate may require 24—96 h the dibutyltin dilaurate, 10—20 min. Heat and moisture accelerate the curing rate, but to a lesser degree than ia the case of the polysulfide mbbers. 

Initially, the water slowly reacts with the isocyanate. However, the reaction can be catalyzed with an appropriate catalyst, such as dibutyltin dilaurate or a morpholine tertiary amine catalyst. The isocyanate will react with water to form a carbamic acid, which is unstable and splits off carbon dioxide, to produce a terminal amine end group (see p. 76 in [6]). This amine then reacts with more isocyanate-terminated prepolymer, as shown above, to form a polyurea. This process repeats itself, building up molecular weight and curing to become a polyurea-polyurethane adhesive. 

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]. 

Catalysts serve a dual purpose in one-component moisture-curing urethanes. The first purpose is to accelerate the prepolymer synthesis. The second purpose is to catalyze the curing reaction of the adhesive with moisture. The most common catalysts used to promote both prepolymer formation (NCO/OH) and later the adhesive curing reaction (NCO/H2O) are dibutyltin dilaurate and DMDEE ((tertiary amine. A stabilizer such as 2,5-pentanedione is sometimes added when tin is used, but this specific stabilizer has fallen from favor in recent years, due to toxicity concerns. DMDEE is commonly used in many one-component moisture-curing urethanes. DMDEE is one of the few tertiary amines with a low alkalinity and a low vapor pressure. The latter... 

The unblocking temperature usually refers to the temperature at which the blocked urethane system must be heated for 30 min in order to achieve cure. The reaction can be accelerated by curing at higher temperatures and/or by the addition of catalyst, as shown in Fig. 6 [62]. Common urethane catalysts like dibutyltin dilaurate are known to decrease the unblocking temperature. 

Liquid poly(caprolactone) triol — 540 MW Dibutyltin dilaurate catalyst — 0.001% by weight... 

Open times of two-component urethanes can vary widely, depending on the level of catalyst. Reaction times can vary from 90 s to over 8 h. Dibutyltin dilaurate is the most common catalyst employed to catalyze the urethane reaction. This is normally added to the polyol side. A tertiary amine may also be added in small amounts. Tin catalysts do not catalyze the amine/isocyanate reaction very well. Acids, such as 2-ethyl hexanoic acid, may be employed to catalyze the amine/isocyanate reaction where needed. 

Source Courtesy of ARCO Chemical Co. Mbis(2-Hydroxypropyl)aniline (Upjohn Co.). Dibutyltin dilaurate. 

Detection and result The chromatogram was freed from mobile phase (heated to 110°C for 30 min) and then exposed to bromine vapor for 1 h in a chamber, after blowing off excess bromine from the layer it was immersed for 1 s in the reagent solution. On drying in air dibutyltin dilaurate hRf 25 — 30), dibutyltin dichloride (kR( 25 — 30), dioctyltin oxide (hR( 40), tributyltin oxide (hRf 80), tributyltin chloride (hRf 80) and tetrabutyltin (hRf 85-90) produced persistent blue zones on a yellow ochre background (Fig. 1). 

Fig. 1 Chromatogram of organotin compounds. Dibutyltin dilaurate (1), dibutyltin dichloride (2), dioctyltin oxide (3), tributyltin oxide (4), tributyltin chloride (5), tetrabutyltin (6).

A prepolymer is made first by charging Pluracol E2000 [1000.0 g, 1.0 eq., poly(ethylene oxide), 56 OH, BASF] to a suitable container equipped with a mechanical stirrer and a nitrogen gas inlet. Flush the container with dry nitrogen and add Desmodur W (264.0 g, 2.0 eq., 4,4 -methylene-bis(cyclohexyl isocyanate), 31.8% NCO, Bayer). While maintaining a positive N2 pressure on the reaction mixture, stir and heat at 80°C for 2 h. Cool the product to room temperature and check the NCO content (theory = 3.32 %). It might be necessary to warm the highly viscous prepolymer to take samples for titration. To a portion of this prepolymer (250.0 g, 0.2 eq.), add Dabco T-12 (0.25 g, dibutyltin dilaurate,... 

A three-necked flask equipped with a condenser and stirrer was charged with the PET depolymerization product (0.05 mol of BHET and dimer in the ratio of 80 to 20 wt%), 0.05, 0.10, and 0.15 mol of e-caprolactone (in separate experiments), and 0.1 wt% of dibutyltin dilaurate. The reaction mixture was heated at 150°C for 2 h. The resulting co-oligomer (0.01 mol) was dissolved in 500 mL of tetrahydrofuran in a three-necked flask equipped with a condenser and a stirrer. After the temperature was raised to 67°C, a solution of 0.01 mL of hexamethylene diisocyanate in 50 mL of tetrahydrofuran was added dropwise. After heating and stirring the reaction mixture for 12 h, it was cooled and precipitated in ether. The polyurethane precipitate was collected by filtration and dried at 70°C for 12 h. 

Dibasic acid monomers, 59 Dibasic acid poly esterifications, 17 Dibromo derivatives, 82 Dibutyltin dilaurate (DBTDL), 232 Dicarboxylic acid monomers, volatilization of, 72... 

I PCS (1999c) International Chemical Safety Card — Dibutyltin dilaurate. Geneva, World Health Organization, International Programme on Chemical Safety (ICSC 1171 http //www.ilo.org/ public/english/protection/safework/cis/products/icsc/dtasht/ icsc11/icsc1171. htm). 

Triethylenediamine (DABCO) and dibutyltin dilaurate (DBTDL) have been used as catalysts with concentrations of 0.25 and 0.06Z (w/w) on binder, respectively. 

Synthesis of Polyurethanes. In the "prepolymer method" employed in this study, MDI (2 equivalents) and PPG (1 equivalent) were reacted at 60°C in the presence of 1% dibutyltin dilaureate as catalyst, in the melt. The course of the polymerizations was followed spectroscopically by observing the intensity of the — NCO peak in the IR (Scheme III). 

Polyurethane networks were prepared from polyoxypropylene (POP) triols(Union Carbide Niax Polyols) after removal of water by azeotropic distillation with benzene. For Niax LHT 240, the number-average molecular weight determined by VPO was 710 and the number-average functionality fn, calculated from Mjj and the content of OH groupSj determined by using excess phenyl isocyanate and titration of unreacted phenyl isocyanate with dibutylamine, was 2.78 the content of residual water was 0.02 wt.-%. For the Niax LG-56, 1 =2630, fn=2.78, and the content of H2O was 0.02wt.-%. The triols were reacted with recrystallized 4,4"-diphenylmethane diisocyanate in the presence of 0.002 wt.-% dibutyltin dilaurate under exclusion of moisture at 80 C for 7 days. The molar ratio r0H = [OH]/ [NCO] varied between 1.0 and 1.8. For dry samples, the stress-strain dependences were measured at 60 C in nitrogen atmosphere. The relaxation was sufficiently fast and no extrapolation to infinite time was necessary. 

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