Urea-formaldehyde resins moulding materials

Phenol-formaldehyde was reported as the first commercially synthetic polymer (1899) which was introduced as BakeliteT by Baekeland in 1909. This was the period which marked the dawn for the production of commercial synthetic thermosetting polymers. Other advances in the field included the discovery of urea-formaldehyde resins in 1884 and the beginning of their commercialization as Beetle moldable resin in 1928, followed by thiourea-formaldehyde (1920), aniline-formaldehyde (Cibatine by Ciba, 1935) and melamine-formaldehyde (1937) moulding powders. The year 1909 marked the discovery of epoxy compounds by Prileschaiev, which were not used until World War 2. The first thermoset polyesters, invented by Ellis, date back to 1934 and in 1938 was reported their first use in the forms of glass-reinforced materials [1]. 

Melamine (I,3,5-triamino-2,4,6-triazine) was first prepared by Liebig in 1835. For a hundred years the material remained no more than a laboratory curiosity until Henkel patented the production of resins by condensation with formaldehyde. Today large quantities of melamine-formaldehyde resins are used in the manufacture of moulding compositions, laminates, adhesives, surface coatings and other applications. Although in many respects superior in properties to the urea-based resins they are also significantly more expensive. 

Moulded phenolic resins were first used commercially in 1910 it is convenient here to take these resins as a group with urea-formaldehyde and melamine, since together they were complementary to the earlier thermoplastic materials and because their particular qualities helped to open new markets. 

Currently, one of the most important commercially available materials today are the urea-formaldehyde (U-F) resins. Their applications include coatings, adhesives, castings, moulding compounds and textiles. Maciel et al. have produced a series of extensive papers in this area concentrating on both and CP/MAS [13-16]. 

CIBA had developed Cibanoid urea-formaldehyde, Cibanit aniline-formaldehyde, and melamine-formaldehyde resins. See Hans Stager, Modern organic materials at the Swiss National Exhibition Zurich, 1939, British Plastics and Moulded Products Trader, 11 (1939), 254-257. 

The principal thermosetting moulding materials are the phenol-formaldehyde (PF), urea-formaldehyde (UF). melamine-formaldehyde (MF). polyester, and epoxy resins (8.N.3, 6.N.1, 6.N.2). The prices of the cheapest resins are just... 

Melamine was first isolated by Liebig in 1834 from the mixture obtained by heating ammonium thiocyanate. A technically feasible route to melamine was developed in 1935 by Ciba AG (Switzerland) and at the same time Henkel patented the production of resins from melamine and formaldehyde. In general, melamine-formaldehyde polymers resemble urea-formaldehyde pol)miers but they have improved resistance to heat and water. The two materials have therefore found application in similar areas, melamine-formaldehyde resins now being widely used in the production of moulding powders, laminates, adhesives, surface coatings and textile finishes. 

As with resins, moulding powders based on melamine are used for specialised applications. The two main areas of application are tableware, where their improved water and scratch resistance compared to urea based materials makes them ideally suitable for this purpose, and for high performance electrical goods. Their electrical properties are superior to urea formaldehyde based materials under conditions of high temperature and humidity. They can be made in more attractive colours than phenolic moulding powders and have superior track resistance. 

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