Melamine Compounds

This particular representation makes it easy to visualize formaldehyde as a step-growth monomer of functionality 2. Our principal interest is in the reactions of formaldehyde with the active hydrogens in phenol, urea, and melamine, compounds [II] [IV], respectively ... 

Parts molded from melamine compounds have a hard scratch resistant surface, practically no odor or taste, good electrical properties, fair arc track resistance, decorative appearance, and color fast characteristics. 

The specific gravity range is from 1.45 to 2.00. The principal use of melamine compounds has been in the dinnerware field. They are widely used in electrical switch gear applications where arc track resistance is very important. In some cases the melamine phenolic compounds are used to produce electrical switch gear where arc track requirements are not so severe. Other applications are ignition systems (distributor cap), housings, and other decorative applications. 

Dyes can also be incorporated into hydrogen-bonded superstructures using the complementarity of the hydrogen bond donors and acceptors. The addition of a perylene bisimide dye to chiral dialkyl melamine derivatives leads to aggregates (Fig. 26) which show induced circular dichroism in the dye part of the assembly in methylcyclohexane as well as the formation of mesoscopic fibres when the solvent is evaporated [227]. The melamine compounds... 

Two main steps are to be distinguished in the production and further conversion of melamine-formaldehyde resins (i) the addition reaction of formaldehyde and melamine to form methylolated melamine compounds, and (ii) methylene and ether bridge formation via condensation reactions releasing water (section 2.2.1). Since spray-dried methylolated melamine resins (MF resins) are studied (see experimental), the cure of MF resins is confined to the condensation reactions of the latter step. 

Another trend in many applications is towards halogen-free products or at least to combinations which will permit a reduction in the percentage of halogen. Japanese patents have opened up the market for melamine compounds that can also be used in combination with other FRs such as magnesium hydroxide or even a filler like talc. 

The product also works in non-halogenated systems. It can be used with ATH, MgO, ammonium polyphosphate, silica, silicone polymers or melamine compounds in polyolefins, urethanes, polyamides and others. In the silicon containing systems, Firebrake ZB is understood to form a borosilicate glass at polymer combustion temperatures. 

Data sheet values. Table 2.25 provides a list of property values for a range of urea compounds and Table 2.26 shows a similar list for melamine compounds. 

A recent DuPont patent discloses a novel way of making condensed melamine phosphates. Melamine pyrophosphate made in this way is claimed to have improved thermal stability. Budenheim is another leading producer of melamine compounds, such as melamine phosphate (Budit 310, 312), and pyrophosphate (Budit 311). The latter is an effective low-cost flame retardant with a low water solubility and good thermal stability. It is used in glass filled polyamides. 

Zinc borate can be used in halogen-lfee systems in conjimction with metal hydroxides, ammoniiun polyphosphate and melamine compounds. With silicones, it is believed to form a borosilicate glass during combustion. Incidental advantages of zinc borate can include smoke... 

Materials/characteristic.s Some inorganic fillers. Nitrogen-donors melamine compounds. Antimony compounds with halogen donors. Halogenated containing chlorine, bromine. Halogen-free systems aluminium trihydroxide (ATH), magnesium hydroxide, zinc borate. Intumescent systems phosphorus compounds. 

According to the producer Eurobrom BV, the world FR market is worth more than US 2.3 billion, embracing some 150-200 grades, based mainly on halogens, phosphorus, inorganics, and melamine compounds, and making up about 2 7-31% of the US 8.6 billion performance additives market. 

The creation of a hexameric melamine compound gives very high positive cooperativity for the creation of a supramolecule containing six isocyanuric acids. Mathias, J. P., Seto, C. T., Simanek, E. E., and Whitesides, G. M. "Self-Assembly through Hydrogen Bonding Preparation and Characterization of Three New Types of Supramolecular Aggregates Based on Parallel Cyclic CA3-M3 Rosettes. " /. Am. Chem. Soc., 116,1725-1736(1994). 

TABLE VII Summary of Data on Dissociation Constants of Melamine Compounds at 25 3°C ... 

The open buss kneader (Fig. 2.18fc) works with an external screw bearing in the production of pastel colors in the urea and melamine compounds. When processing epoxy, polyesters (with or without glass fibers), and phenolics, the external bearing is not required. Both the open buss kneader and the Werner Pfliederer compounding unit will process the compounds and also control the granulation and flow properties. 

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