Isocyanate resins

Unlike the epoxy resins where the members differ only in their size, the isocyanate resins differ markedly according to the choice of components, but all have the common feature of a diisocyanate as one of the components. Two of the most widely used diisocyanates are tolylene diisocyanate and hexamethylene diisocyanate which have the following structures ... 

The manufacture of MDF, with a few exceptions, duplicates the manufacture methods for dry-process hardboard, described at length herein. One exception to it is that most MDF is made in the medium-density range, 640—800 kg/m3 although small amounts are made at lower or higher densities. Second, the vast majority of MDF is made with UF resin adhesives with resin requirements in the 7—11% range, and wax is usually added at the 0.50—0.75% level. A small amount of exterior-grade MDF is made with isocyanate resin. 

Methyl-5-phenyl-pyrazol-l-yl)-benzoic Acid (27). A mixture of 4-hydrazino-benzoic acid hydrochloride (113 mg, 0.6 mmol) and morpholine-based resin (3) in MeOH (2 ml) was treated with 1-phenyl-butane-1,3-dione (81.5 mg, 0.5 mmol) and shaken for 2.5 h. The MeOH was allowed to evaporate under a stream of N2. DCM (4 ml) was then added to the reaction mixture followed by the addition of isocyanate resin (15) (350 mg). The resulting reaction mixture was shaken for 16 h at which time additional amounts of isocyanate resin (15) (120 mg) were added. The mixture was shaken for 4 h followed by filtration. The filtered resin was washed with DCM (2 x 1.5 ml). Upon concentration of the organic filtrate, clean product was obtained. MS 278.11 (M + 1). 

N-Benzyl-2-bromo-N-methyl-benzamide (35). A suspension of morpholine resin (3, 0.63 mmol) in DCM (2 ml) was treated with. V-methyl-benzylamine (0.23 mmol) and 2-bromobenzoyl chloride (0.146 mmol). The reaction mixture was shaken for 5 h. Isocyanate resin (15, 0.2 g) was added followed by DCM (1 ml). The reaction mixture was then shaken for 16 h. Filtration of the resin followed by concentration of the filtrate gave the purified product. 

As this area of polymer supported reagents continues to expand the complexity of the polymeric supported resins has increased [18]. Although electrophilic supported reagents like the isocyanate 5 and acid chloride 12 have been shown to be efficient reagents for the covalent capture for primary and secondary amines (Table 1), they are not without their difficulties. The isocyanate resin is particularly expensive and the loading is rather low (approximately 1 mmol NCO/gram). 

The isocyanate reaction is several orders of magnitude faster than the epoxy reaction. Hence, attempts to cure mixtures of epoxy and isocyanate resins must provide for essentially complete consumption of all -NCO groups before any of the epoxy rings can react. 

The development of useful adhesive compositions based on the interaction of isocyanate resins with natural polymers such as lignin, proteins, and carbohydrates. 

Surface oxidation processes have also been used as pretreatments for improving the bonding strength of adhesives. Brink et al. [9] reported that the wet bonding strength of plywoods or particleboards manufactured using phenol formaldehyde increased after pretreatment of wood with nitric acid. Mari et al. [10] also reported that nitric acid oxidation reduced the amount of isocyanate resin adhesive required to manufacture particleboard and improved the mechanical properties and biological resistance of boards. 

Figure 25 Modulus of rupture of particleboards combined with chemically modified particles. U, Untreated particles A, acetylated particles B, benzylated particles SG, specific gravity of board. Note isocyanate resin was used as a binder for particles U and A. Benzylated particles were used on the surfaces of the boards. Willow Salix Arakiana koidz.) particles were used to manufacture boards.

Using an isocyanate resin, at 3% solids content, on the same aspen flakes as described above, dry internal bond strength decreased by only 2%, MOR decreased by 23%, and MOE decreased by 15% on boards made from acetylated flakes as compared to boards made from nonacetylated flakes [37]. This is just one more example of how the type and level of the resin used influenced composite board mechanical properties. 

Phenol formaldehyde resin, isocyanate resin, Tyromyces palustris, Coriolus versicolor, Chaetomium globosum. 

Use Determination of tungsten and sulfates, polymer and dye intermediate, corrosion inhibitor, epoxyresin hardening agent, isocyanate resins, polyamides. 

Compatibility of nitrocellulose with a wide variety of commercial urethane resins v as readily established. Laboratory work was needed, however, to develop useful formulations with excellent properties. The aliphatic-type isocyanate resins now available produce industrial coatings with good initial color and good color stability when combined with nitrocellulose. 

MAJOR USES Used in the production of polyurethane foams, dyes, isocyanate resins, polyamides, rubber and elastomeric fibers antioxidant for lubricating oils corrosion preventative curing agent. 

Very recently a rapid method for the preparation of effective polymer-supported isocyanate resins has been reported [31]. Gel-type isocyanate resins tvere generated from aminomethyl resins and inexpensive substrates as alternatives to the commercially available, expensive macroporous polystyrene isocyanate supports. Several isocyanates have been investigated phenyl diisocyanate (PDI) tvas found to be the most efficient. Aminomethyl resin was pre-swollen in NMP, mixed with 2 equiv. PDI, and irradiated at 100 °C for 5 min (Scheme 16.7). Filtration, washing with NMP and DCM and drying under vacuum furnished the corresponding isocyanate resin. The reactivity of this novel gel-type resin was better than that of commercially available methyl isocyanate resins and it was successfully used for purification of a small amide library [31]. 

Scheme 16.7. Preparation of gel-type isocyanate resin from aminomethyl resin.

At 100 °C bulk conversion of primary amines occurs quantitatively in the presence of secondary amines. Highly branched, blocked isocyanate resins are available from polyamines and polyols (Scheme 13.1). Since nontoxic components are used, biocompatible polymers are available for biomedical applications. A large variety of reactive oligomers and highly functionalized intermediates for... 

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