Methylol urea

Urea - formaldehyde polymers. Formalin and urea (usually in the molecular proportions of 3 2) condense in the presence of ammonia, pyridine or hexamine to give urea - formaldehyde polymers, known commercially as Bedle or Plaskon, and are widely used as moulding powdens. It is believed that the intermediate products in the condensation are methylol-urea and dimethylol-urea ... 

THP—Amide Process. THP has also been made directly from phosphine [7803-5-27] and formaldehyde. The THP so generated contains one less mole of formaldehyde than either THPC or THPOH. It can be used in a THP—amide flame-retardant finish. The pad formulation contains THP, TMM, methylol urea, and a mixed acid catalyst (93—95). 

UE suspension 18 Tiquidproducts 75 urea, methylol ureas, MDU, DMTU 15 TMTU, TMPU 10... 

With the present state of knowledge it appears that in the first part of the second-stage methylol ureas condense with each other by reaction of an CH20H group of one molecule with an NH2 group of another (Figure 24.2). 

Modification of urea-formaldehyde resins with other reagents gives rise to a number of useful materials. For example, co-condensation of urea-formaldehyde and a monohydric alcohol in the presence of small quantities of an acidic catalyst will involve simultaneous etherification and resinification. n-Propanol, n-butanol and isobutanol are commonly used for this purpose. As an example n-butanol will react with the methylol urea as shown in Figure 24.4. 

N,N -Di (methylol)-urea and derivs 5 D1359 N,N -bis (2,2,2-trinitroethyl)-urea 5 D1359 N-(methylol)-N -(2,2,2-trinitroethyl)urea 5 D1359... 

With urea, formaldehyde forms two stable IV.O-hemiacetals (Figure 9.25) a 1 1 adduct ( methylol urea ) and a 1 2 adduct ( dimethylol urea ). When they are heated, both compounds are converted to macromolecular IV.lV-acetals (Figure 9.26). A three-dimensionally cross linked urea/formaldehyde resin is produced it is an important plastic. 

Fig. 9.26. Mechanism of the formation of a urea/formalde-hyde resin from methylol urea (R1 = H in formula A possible preparation Figure 9.25) or dimethylol urea (R1 = HO—CH2 in formula A possible preparation Figure 9.25). The substituents R1, R2, and R3 represent the growing —CH2—NH— C(=0)—NH—CH2— chains as well as the derivatives thereof that are twice methylenated on N atoms.

Another category of durable hand builders are formaldehyde-containing thermosetting polymers. These products are usually supplied as dispersions or aqueous solutions of precondensates of urea or melamine with formaldehyde, for example di-methylol urea or di- to hexa-methylol melamine and their methyl ethers. The thermosetting polymers are comparatively inexpensive and provide fabrics with stiffness and resilience. However, they have a tendency to reduce abrasion resistance, yellow after exposure to heat, and release formaldehyde. Melamine-based hand builders are more highly crosslinked than urea-based products and are accordingly more durable. Butylated urea condensates are especially useful for rayon fabrics (see also Chapter 5 Easy-care and durable press finishes of cellulosics). 

KAURIT W consists of a dimethylol urea modified by etherification. It is supplied in the form of an approx. 80% paste that dissolves readily in warm water. KAURIT W is less reactive than KAURIT S, but it has far better liquor stability owing to the etherification. The bath stability of other, unmodified methylol-urea compounds can be improved markedly by addition of 30-50% of KAURIT W. 

See dimethylol urea methylol urea melamine resin urea-formaldehyde resin. 

The advantage of dimethylol-urea is that the correct quantities of formaldehyde and urea are available in a pre-prepared state. It also ensures that, on polymerization, there will be an extremely high yield of the completely cross-linked product shown in (2) which is free from amino or imino groups. Methylol ureas, however, are comparatively unstable, and for this reason there is a tendency to prefer the more stable methyl esters, such as shown in (3), which condense with the elimination of methyl alcohol ... 

Urea and melamine resins (including di-methylol urea)... 

EINECS 213-674-8 HSDB 5776 1-(Hydroxymethyl)urea Methylol urea Methylolurea Methylolureas Mono-(hydroxymethyl)urea Monomethylolurea N-(Hydroxy-methyl)urea N-Methyiolurea NSC 13181 Urea, (hydroxymethyl)-, Used In manufacture of urea-formaldehyde resins. Colorless crystals mp = 111 soluble H20, EtCH, MeOH, AoOH, insoluble in Et20. 

In the encapsulation process depicted in Figure 5.82(c), polymerization is initiated in the water phase of oil-in-water emulsion. As the molecular size of the polymer increases, it deposits at the water-oil interface where it continues to grow forming a cross-linked polymer capsule wall. In a typical example, methylol urea or methylolmelamine is added to the aqueous phase along with an ionic polymer. The pH is adjusted to 3.5—4.5 and the mixture allowed to react for 1-3 h at 50-60°C. The ionic polymer in the aqueous phase assists deposition of the aminoplastic at the water-oil interface. 

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