Formaldehyde urea reaction

Urea—Formaldehyde Reaction Products. Urea—formaldehyde (UF) reaction products represent one of the older controlled release nitrogen technologies. An early disclosure of the reaction products of urea [57-13-6] and formaldehyde [50-00-0] was made in 1936 (1) (Amino resins and plastics). In 1948, the USDA reported that urea (qv) and formaldehyde (qv) could react to produce a controlled release fertilizer at urea to formaldehyde mole ratios (UF ratio) greater than one (2). 

In typical manufacturing processes the freshly prepared urea-formaldehyde initial reaction product is mixed with the filler (usually with a dry weight... 

By far the preponderance of the 3400 kt of current worldwide phenolic resin production is in the form of phenol-formaldehyde (PF) reaction products. Phenol and formaldehyde are currently two of the most available monomers on earth. About 6000 kt of phenol and 10,000 kt of formaldehyde (100% basis) were produced in 1998 [55,56]. The organic raw materials for synthesis of phenol and formaldehyde are cumene (derived from benzene and propylene) and methanol, respectively. These materials are, in turn, obtained from petroleum and natural gas at relatively low cost ([57], pp. 10-26 [58], pp. 1-30). Cost is one of the most important advantages of phenolics in most applications. It is critical to the acceptance of phenolics for wood panel manufacture. With the exception of urea-formaldehyde resins, PF resins are the lowest cost thermosetting resins available. In addition to its synthesis from low cost monomers, phenolic resin costs are often further reduced by extension with fillers such as clays, chalk, rags, wood flours, nutshell flours, grain flours, starches, lignins, tannins, and various other low eost materials. Often these fillers and extenders improve the performance of the phenolic for a particular use while reducing cost. 

Formox [Formaldehyde by oxidation] A process for oxidizing methanol to formaldehyde, using a ferric molybdate catalyst. Based on the Adkins-Peterson reaction, developed by Reichold Chemicals, and licensed by that company and Perstorp, Sweden. Acquired by Dyno Industries in 1989. The process uses formaldehyde produced in this way to make formaldehyde-urea resin continuously. A plant using this process was to be built in Ghent by 1991, owned jointly by Dyno and AHB-Chemie. Licensed to 35 sites worldwide. Several other companies operate similar processes. 

The urea-formaldehyde polymer is formed by a multi-step reaction process between urea and formaldehyde. The initial phase is a methylolation of the urea under slightly alkaline conditions with a formaldehyde-urea (F/U) molar ratio of 2.0 1 to 2.4 1. Condensation of the methylolureas from the methylolat ion reaction is at atmospheric reflux with a pH of 4 to 6. This condensation polymerization continues to a pre-determined viscosity, at which time the pH is adjusted with a suitable base to 7-3 to 8.0. The adhesive is then concentrated to a total solids content of 50 to 60 percent by vacuum distillation. Additional urea is then normally added to produce a final F/U molar ratio of 1.6 1 to 1.8 1. 

Monodispersely-sized submircon zirconia colloids are useful starting material for ceramics, catalysts, and chromatographic stationary phases. One such process (polymerization-induced colloid aggregation or PICA process) requires entirely reproducible aqueous zirconia sols with no surfactants [1,2]. In the PICA process developed by Her and McQueston [3], the concentrated ( 20 wt %) 100 nm zirconia colloids are aggregated by urea-formaldehyde polymerization reaction to produce the porous zirconia particles in the size range of 4 - 6 pm [1,2],... 

The large group of phenol-formaldehyde, urea-formaldehyde, and melamine-formaldehyde polymers are also prepared by carbonyl-addition-substitution reactions. Their final crosslinking reaction occurs in the solid state, however, the polymers are amorphous. Crystalline linear polymers have been obtained using parasubstituted phenols. But up to now only relatively low molecular weight polymers have been prepared (5). 

The unextractable acid in wood plays a major role in the catalysis of the urea-formaldehyde polycondensation reaction. The significance of this indication must be viewed in contrast to previous investigations which have attempted to correlate properties of wood with the properties or amounts of extractives. It would not be prudent to generalize regarding the effect of unextracted acids because only seven species were studied. However, in future studies these observations may be found to be generally true for most, if not all, species. 

Since the original Tootal patent there has been much research on alteration of the properties of cellulosic materials by the formation of polymers in situ. The original formaldehyde urea method for the crease-resistant finish is probably still -the most commonly used. Dimethylol-urea is now used as the monomer instead of a mixture of urea and formaldehyde. It is the product of the reaction of one molecule of lurea with two molecules of formaldehyde ... 

The natural abundance 15NNMR spectra of urea-formaldehyde and melamine-formaldehyde adducts and resins (recorded with approximately 20000 pulses) can be used for direct determination of different types of amino groups. The spectra of a urea-formaldehyde resin (1 1 formaldehyde/urea ratio) after 15 and 60 min of reaction are shown in Fig. 3. On the basis of chemical shifts of urea based model compounds (monomethylol-, Af,AT-dimethylol- and N,N,N -trimethylol-ureas) the following assignment of nine 15N resonances is proposed... 

CAS 68002-19-7 93686-54-5 EINECS/ELINCS 297-708-7 Synonyms Butylated polyoxymethylene urea (INCI) Butylated urea-form-aldehyde resin Poly (urea-co-formaldehyde), butylated Urea, polymer with formaldehyde, butylated Urea, reaction prods, with butyl alcohol and formaldehyde Classification Eormaldehyde copolymer... 

Urea, polymer with formaldehyde, butylated Urea, reaction prods, with butyl alcohol and formaldehyde. See Urea-formaldehyde resin, butylated... 

Methylolurea n. H2NCONHCH2OH. First stage in the formation of urea formaldehyde resins. Reaction products of urea and formaldehyde. Monomethylol urea is obtained by reacting one molecule of formaldehyde and one molecule of urea. 

Imidazolidinyl urea (115). This releases relatively small amounts of formaldehyde. Cross-reactions to and from diazolidinyl urea occur. Patch-test concentrations are 1% aqua or 1% pet (Ford and Beck 1986 Hectorne and Fransway 1994). 

In some polycondensations, new functional groups are created by reactions of the monomers. Thus, methylol end groups are formed by the initial reactions of formaldehyde with other monomers, and their condensation reactions shown in the last two rows of Table 3.1 occur in later stages of formaldehyde/urea and formaldehyde/phenol polymerizations (see Section 3.3.4). 

The main raw materials used for the synthesis of ureo-formaldehyde resins are urea and formaldehyde. Urea is a solid, crystalline, water-soluble substance. It has a weak basic character. Formaldehyde is used in solution form at 30-55% concentration. It is of advantage to use either high-concentration formaldehyde solutions or precondensates. Both processes provide a satisfactory economic efficiency and diminish residual water content. Precondensates can be obtained through the reaction between urea and formaldehyde (molar ratio 1 1.1-6), at T = 45 C and pH = 6.8-8.0 [19]. 

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