Aluminum hydroxide fillers

Bayer aluminum hydroxides in most grades are sold by all major U.S. alumina producers. Other firms offering aluminum hydroxide fillers probably operate reprocessing faciHties to grind or otherwise treat hydroxide obtained from the primary producers. Countries exporting small amounts to the United States are Japan, Germany, Canada, and the UK. 

Synthetic Marble. Synthetic marble-like resin products are prepared by casting or molding a highly filled monomer mixture or monomer—polymer symp. When only one smooth surface is required, a continuous casting process using only one endless stainless steel belt can be used (52,53). Typically on the order of 60 wt % inorganic filler is used. The inorganic fillers, such as aluminum hydroxide, calcium carbonate, etc, are selected on the basis of cost, and such properties as the translucence, chemical and water resistance, and ease of subsequent fabrication (54,55). 

Thermal Analyses. Thermal analysis often complements x-ray data in providing information on phase composition. The thermal behavior of aluminum hydroxides is particularly important in filler type appHcations. 

Approximately 600,000 metric tons of aluminum hydroxides were used in chemical appHcations in the United States in 1988 40% as fillers, 45% for the production of aluminum chemicals, and 15% for various other uses. Carpet backing was the principal filler type appHcation foUowed by polyester products. 

White pigments such as calcium carbonate, aluminum hydroxide, silica, kaolin, or urea-formaldehyde resin are used as filler. The filler functions as an absorbent of melted components to prevent their adhesion on the thermal head. Thus, the filler is required to be high in oil absorption and not to wear the thermal head. 

Aluminum hydroxide is used in stomach antacids (including Maalox , Mylanta , and Delcid ), as a desiccant powder in antiperspirants and dentifrices in packaging materials as a chemical intermediate as a filler in plastics, rubber, cosmetics, and paper as a soft abrasive for brass and plastics as a glass additive to increase mechanical strength and resistance to thermal shock, weathering, and chemicals and in ceramics (HSDB 1995). Aluminum hydroxide is also used pharmaceutically to lower the plasma phosphorus levels of patients with renal failure (Budavari et al. 1989 Sax and Lewis 1987). 

This is the second most widely used fire-retardant filler. It is more expensive than aluminum hydroxide, but has a higher decomposition temperature (about 300°C), making it more suitable for use in thermoplastic applications where elevated processing temperatures are encountered. 

Boehmite is, in effect, partly decomposed aluminum hydroxide, where two-thirds of the water has been removed. Although it has been promoted as a fire retardant in its own right, but because of the relatively low water content, does not seem to be very effective for this purpose. However, it does seem to have some potential in mixtures with other fire-retardant fillers and this is where it is now being targeted.6... 

There is evidence to show that the particle size of the filler also plays a significant role in flammability resistance. For example, below a certain particle size (about 1-2 pm), in many tests, including oxygen index, aluminum hydroxide shows enhanced fire-retarding performance,34 which may be associated with the rate of filler decomposition and/or with the formation of a more stable ash. However, it has been found that the particle size effect is absent, or less evident, in the cone calorimeter test.35 Similarly, particle size reduction has been shown to enhance fire retardancy in magnesium hydroxide-filled PP in this case, samples were characterized by the UL94 test.36 This raises the question as to whether further reductions in particle size to the nanoscale will lead to an additional increase in flammability performance, and perhaps enable filler overall levels to be significantly reduced. This aspect is considered in a later section. 

Filler-polymer interactions have also been observed in EVA copolymer yielding differences in fire retarding effectiveness between ATH and MH.42 In EVA with 30% vinyl acetate content, magnesium hydroxide had an oxygen index of 46%, whereas aluminum hydroxide gave a value of... 

A method for synthesizing nano-aluminum hydroxide with an ATH core and alkyl hydrocarbon chain shell structure has been described.94 In the resulting composites prepared using EVA, mechanical properties of the nanofilled material were almost the same as a conventional 1 pm sized ATH variant however, the HRR of the former composition was markedly lower. In this work 10 phr of filler was used. 

The aluminum hydroxide gel referred to in the USP 28 is used in cosmetics as an emollient, filler, humectant, a mild astringent, and viscosity controlling agent. In pharmaceutical preparations it is used as an adsorbent, and as a protein binder. It is also used therapeutically as an antacid, and as an abrasive in dentrifrices. It is not, however, used as a vaccine adjuvant. 

Zinc borate is an inorganic flame retardant which can be used by itself or in combination with aluminum hydroxide or magnesium hydroxide with which it forms synergistic mixtures of high performance flame retardants. It is frequently used as a surface coating on these two fillers. It reduces smoke emission and promotes char formation. 

The modification of aluminum hydroxide by dicarboxylic anhydride has similar kinetics (Figure 6.12). Figure 6.13 shows that the linkages formed are durable since they withstand of 30 h Soxlet extraction with n-hexane. Only when more than 1 % of dicarboxylic anhydride is used does it becomes associated with the filler through physical forces. In this condition it can be removed by extraction. The concentration of reactive functional groups on the filler surface has a strong influence on the modification processes. 

Typical fillers calcium carbonate, barium sulfate, talc, kaohn, mica, quartz, sand, glass spheres, silica, titanium dioxide, aluminum hydroxide, carbon fiber, glass fiber, aramid fiber, aluminum, copper, silver, iron, graphite, molybdenum disulfide, zirconium silicate, hthium aluminum silicate, vermiculite, slate powder, titanium boride, ground rubber, iron oxide, microvoids... 

Typical fillers calcium carbonate, clay, aluminum hydroxide, magnesium hydroxide, zinc oxide, silica, quartz, red phosphorus... 

Fire resistance is an important property of phenolic resins. The combination of phenolic resin with Expancel expandable microspheres leads to many useful products. Composites for high speed train interiors take advantage of the light weight, excellent fire rating, and very low thermal conductivity. Polyester filled with aluminum hydroxide is an alternative solution for train interior materials. The resin and filler can be easily processed when viscosity regulating additives are added. 

Typical fillers aluminum hydroxide, silica, titanium dioxide, glass fiber, mica, barium sulfate, titanium fiber, nickel, aluminum... 

Typical fillers calcium carbonate, calcium sulfate, silica, organic fibers, graphite, mica, bentonites, sand, aluminum hydroxide, sepiolite, rubber particles... 

Typical fillers calcium carbonate, aluminum hydroxide, glass fiber, crashed marble, glass fiber, antimony trioxide, carbon black, quartz, saw dust... 

Manufacturers of various fillers continue studies on altemative systems. Most antimony oxide used as a fire retardant can be replaced by a combination of zinc borate without the loss of other properties (in some cases improvements are reported). Another option is to use the same filler systems which are used in polyethylene insulated cables and wires. These are based on magnesium hydroxide and aluminum hydroxide. These systems pcrfoim as flame retardants but require a high filler concentration which affects jacket resistance and mechanical performance. Recently, new coated grades have been developed which can be used at up to 65 wt% without the loss of properties or productivity (extrusion rates 2,500 m/min of cable are possible). ... 

Still, it is important that fillers interact with the polymer (binder) for various reasons. One is the rheological characteristic of paints. Figure 19.5 shows that many processes may affect how a filler behaves in the system. The simple drying of aluminum hydroxide prior to use contributes to an increased paint viscosity. It should be noted that aluminum hydroxide loses water at 220°C, therefore drying at 80 C may only remove the water adsorbed on the surface of particles. But this is apparently sufficient to increase the interaction with the binder since, when the partially dried filler is added, viscosity almost doubles. Similarly, treatment with 1% triethoxymethacryloylpropylsilane, MPS, contributes to an increased viscosity. This data shows that the same filler can be readily modified to give a variety of different results. 

Western-world bauxite production in 1988 totaled about 90 x 10 t, approximately 90% of which was refined to aluminum hydroxide by the Bayer process. Most of the hydroxide was then calcined to alumina and consumed in making aluminum metal. The balance, which constituted about 2.3 x 10 t in 1988 (Table 2), was consumed in production of abrasives (qv) adhesives (qv) calcium aluminate cement used in binding ceramics (qv) and refractories (qv) catalysts used in petrochemical processes and automobile catalytic converter systems (see Petroleum Exhaust control, automotive) ceramics that insulate electronic components such as semiconductors and spark plugs chemicals such as alum, aluminum halides, and zeoHte countertop materials for kitchens and baths cultured marble fire-retardant filler for acryhc and plastic materials used in automobile seats, carpet backing, and insulation wrap for wire and cable (see Flame retardants) paper (qv) cosmetics (qv) toothpaste manufacture refractory linings for furnaces and kilns and separation systems that remove impurities from Hquids and gases. 

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