2.4- Toluene diisocyanate catalyst

The one-shot methods used to produce flexible polyurethane foams employ quick mixing of a (usually) triol-based polyether of fairly high-molecular weight with toluene diisocyanate, catalyst, and water for gas production (Eq. 21.19). The reaction of water with the diisocyanate rapidly raises the average functionality in the polymerizing system by forming urea, as well as urethane links (Eq. 21.23). 

Yield for the process at low catalyst loading is 95%. AJ-Methyl-toluenediamiae, one of the reaction by-products, represents not only a reduction ia yield, but also a highly objectionable impurity ia the manufacture of toluene diisocyanate. Low concentrations of CO (0.3—6% volume) control this side reaction. 

We have prepared and characterized three linear isosorbide containing polyurethanes with toluene diisocyanate (TDI), 4,4 -diphenylmethane diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HMDI) P(I-TDI), P(I-MDI), and P(I-HMDI). These polyurethanes have been synthesized as described in the experimental section by solution polymerization of isosorbide with the corresponding diisocyanate in dimethylacetamide using dibutyl-tin dilaurate as the catalyst at 75 C for 24 hours. All polymers have been isolated in quantitative yield by precipitation in methanol or water (5). 

Moreover, flexible foams are characterized by utilization of special emulsifiers in their synthesis yielding an open-cell architecture, whereas for rigid foams emulsifiers are chosen that create more closed-cell structures. As diisocyanate for both types, the commercially available mixture of 80% 2,4-toluene diisocyanate and 20% 2,6-toluene diisocyanate is especially suitable. If foam formation is to take place at room temperature, and especially when hydroxy compounds with secondary hydroxy groups are used [poly(propylene glycol)s], the presence of a catalyst is generally required (see Sect. 4.2.1). 

A reconstructed ion chromatogram (GC-MS) containing extractable contaminants isolated from a typical lot of foam is shown in Figure 4. The qualitative composition of the extractable contaminants was provided by GC-MS. Contaminant profiles were identical for each of the two solvent systems employed, methylene chloride (1003 ) and ethyl ether/hexane (5/95). The contaminant chemistry shown here and again in Figure 5 in several instances is consistent with the manufacturing process data shown in the box, most notably the presence of residual toluene diisocyanate (starting materials, see Scheme II) and an aliphatic amine (possible reaction catalyst). 

PS PSF PSU PTFE PU PUR PVA PVAL PVB PVC PVCA PVDA PVDC PVDF PVF PVOH SAN SB SBC SBR SMA SMC TA TDI TEFE TPA UF ULDPE UP UR VLDPE ZNC Polystyrene Polysulfone (also PSU) Polysulfone (also PSF) Polytetrafluoroethylene Polyurethane Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) poly(vinyl butyrate) Poly(vinyl chloride) Poly(vinyl chloride-acetate) Poly(vinylidene acetate) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl fluoride) Poly(vinyl alcohol) Styrene-acrylonitrile copolymer Styrene-butadiene copolymer Styrene block copolymer Styrene butadiene rubber Styrene-maleic anhydride (also SMC) Styrene-maleic anhydride (also SMA) Terephthalic acid (also TPA) Toluene diisocyanate Ethylene-tetrafluoroethylene copolymer Terephthalic acid (also TA) Urea formaldehyde Ultralow-density polyethylene Unsaturated polyester resin Urethane Very low-density polyethylene Ziegler-Natta catalyst... 

Let us now analyze the application of this technique to the formation of a polyurethane synthesized from toluene diisocyanate (TDI, a mixture of 80% toluene 2,4- diisocyanate and 20% toluene 2,6-diisocyanate, as shown in Fig. 5.15) and a stoichiometric amount of a polyfunctional polyol based on sorbitol, using triethylamine (TEA) as a catalyst (Aranguren and Williams, 1986). 

Polyurethane is also used as a foam, mostly in sheet form as an underlay or middle layer for example in fruit bins. The following starting materials for polyurethane foam can be used polyester with hydroxyl end groups made from adipic acid, diethylene glycol, trimethylol propane as well as polyether based on ethylene oxide and/or propylene oxide with free hydroxyl groups in combination with 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Stabilizers, dispersants and amines (as catalysts in amounts up to 1.2 %) can be used. 

Moreover, in situ polyurethane formation was performed by irradiation of the polymeric pyridinium salt in THF containing toluene diisocyanate and catalyst. It is clear that alkoxy pyridinium terminated polymers are useful materials as precursors for block copolymers and hydroxy functional telechelics. The latter are particularly attractive in photoinduced polycondensation and in applications where hydroxyl groups are needed to be protected. 

Ammoxidation is also used for the manufacture of isophthalonitrile from m-xylene. The catalysts claimed in the patents are mixed oxides, e.g., of Mo, V, and Sb. The dinitrile is hydrogenated to m-xylylene diamine and m-diamino-dimethylcyclohexane, used for the production of the corresponding diisocyanates that are less toxic than toluene diisocyanate TDL A different use is for the production of tetrachloroisophthalonitrile, a potent fungicide. 

Dimers, in contrast to trimers, are in dynamic equilibrium with monomer. Toluene diisocyanate dimerizes to a greater extent the lower the temperature, 90% at 10° compared to 73% at 25° (19). In the absence of a catalyst. 

Wood stains and varnishes used indoors contain aliphatic and aromatic hydrocarbons, isocyanates, ketones, and esters. Though these have limited use compared with paint, newly finished building interiors often contain toxic levels of these. Toluene diisocyanate, used as a catalyst in polyurethane wood finishes, is a powerful respiratory irritant and sensitizer. 13 ... 

Di-n-butyltin catalysts are being used in the preparation of polyurethane foams. Most polyurethane foams utilize aromatic isocyanates such as toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI) as the isocyanate, and a polyester or polyether polyols as the coreactant. Tertiary amine catalysts are used to accelerate the reaction with water and formation of the carbon dioxide blowing agent. To achieve a controlled rate of reaction with the polyol, an organotin catalyst can be used. Polyurethane foams are not only applied in place, but are also cast in a factory as slabstocks. These foam slabs are then cut for use in car seats, mattresses, or home furnishings. DBTDL is an excellent catalyst in high resiliency slabstock foams. DBTDL shows an excellent reaction profile for this application replacement for DBTDL in such an end-use is difficult and requires a substantial reformulation of the foam. 

Materials. The polyurethane precursor materials were Adiprene L-lOO (Uniroyal, Inc.), a poly(oxytetramethylene glycol) capped with toluene diisocyanate, eq. mol. wt. 1030 1,4-butanediol (BD) and 1,1,1-trimethylolpropane (TMP) and, as catalyst, dibutyltin dilaurate (DBTDL). Acrylic precursors included n-butyl methacrylate (BMA), washed with 10% aq. NaOH to remove inhibitor tetramethylene glycol dimethacrylate (TMGDM) crosslinker and benzoin sec-butyl ether (BBE) as a photosensitizer. These materials were dried appropriately but not otherwise purified. 

Hafnium triflate has also been used for acylation and alkylation of aromatic compounds.64 It has also been used in aromatic nitration in a process (6.18) that eliminates the usual waste acid from such reactions.65 The products are intermediates in the synthesis of toluene diisocyanates used in making polyurethanes. The catalyst could be reused with... 

Polymerization of 2,4-Toluene Diisocyanate [5b] a. Preparation of Catalyst l-Ethyl-3-methyl-3-phospholene 1-Oxide... 

Using a mixture of castor oil and hydroxyether of bisphenol-A (HBA) as the polyol and reacting with TDI in the presence of DBTDL catalyst at 35°C, a series of polyurethanes are prepared in an air-circulating oven for 48 h. A series of poly(urethane urea)-vinyl polymer hybrid aqueous dispersions are prepared. Waterborne poly(urethane urea) is synthesised from castor oil and polyoxypropylene polyol M = 1000 g moL ), dimethylol propionic acid and isophorone diisocyanate and then neutralised with tertiary amine. The hybrid aqueous dispersion with high oil content poly(urethane urea) exhibits excellent compressive mechanical strength. Sunflower oil-modified waterborne polyurethane resin may also be prepared. The waterborne resin is synthesised from the monoglyceride of the oU, poly(propylene-ethylene) triol, tartaric acid and toluene diisocyanate, then neutralised with triethyl amine. 

SMPU containing polycarbonate segments were synthesized by the prepolymer method of an aliphatic polycarbonate diol. The macrodiol was synthesized by copolymerization of ethylene oxide in the presence of CO2 catalyzed by a polymer supported bimetallic catalyst [60]. In these polycarbonate urethanes Ttrans = 7g and was around 5 C. Another example with higher Ttrans are segmented polyesterurethanes based on a copolymer of L-lactide and e-caprolactone, providing the switching domains as well as the polyurethane from butanediol and 2,4-toluene diisocyanate [52]. Tsw could be adjusted between 28 and 53 °C. Rr was determined between 93 and 100%. 

Synthesis from sucrose ester/half-ester derivatives, monoepoxide and diisocyanate. Sucrose "penta"-soyate (the methanol insoluble fraction of the soap-free product) was reacted at 100°C for 4 hours with a mixture in xylene of 1 mole equivalent cyclic anhydride e.g., phthalic or tetrahydrophthalic anhydride and monoepoxide e.g., styrene oxide or Cardura E (the glycidyl ester of versatic acid), branched C9-Cfatty acids, in the presence of N-benzyl dimethylamine as catalyst. A faster rate was achieved with the phthalic system. The course of reaction between half ester carboxyl groups and epoxide groups was followed by acid value. About 90% reaction was achieved in all cases and to the product was added 1.0 mole toluene diisocyanate (the meucimum amount without gelation) and dibutyl tin dilaurate as catalyst. 

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