Talc, platy

Talc is a hydrated magnesium silicate that is composed of thin platelets primarily white in color. Talc is useful for lowering the cost of the formulation with minimal effect on physical properties. Because of its platy structure and aspect ratio, these extenders are considered reinforcement. Polymers filled with platy talc exhibit higher stiffness, tensile strength, and creep resistance, at ambient as well as elevated temperatures, than do polymers filled with particulate fillers. Talc is inert to most chemical reagents and acids. The actual chemical composition for commercial talc varies and is highly dependent on the location of its mining site. 

Polymers filled with platy talc exhibit higher stiffness, tensile strength, and creep resistance than do polymers filled with standard particulate fillers. These properties are maintained at both ambient and elevated temperatures. Surface treatments for talc particles include magnesium and zinc stearates, silanes, and titanates. 

PolyTalc. [Pfuer] Surface-modified platy talc for polymer applies. 

SUvo-Iine. [Mtmtana Talc] Platy talcs ... 

SterlLine. [M< itana Talc] Platy talcs high purify talcs meeting USP, CTFA, ai Eurtqwan Pharmacopeia specs. for cosmetics, antiperspirants, dusting powders, pharmaceutical excq>ients. 

Finally, creative combinations of low-cost fillers in various forms allow reduced resin content without reducing desired properties. Blends of small and large particles of the same filler material, or blends of plate-like filler particles and coarse filler, help limit the filler s most extreme, unwanted effects on stiffness, strength, or impact behavior. For example, platy talc, mica, or kaolin day in a PO provides stiffness enhancement, which complements the strength properties provided by fiber-shaped wollastonite or the more forgiving impact properties of spherical caldum carbonate partides [7-6]. 

Properties Bright wrh. powrd. 3.6 mean particle size fineness (Hegman) 6 sp.gr. 4.45 dens. 268 Ib/ft bulk dens. 75 Ib/ft (loose) bulldog value 0.0279 gal/lb oil absorp. 11 brightness 94+ pH 8 Cimpact 699 [LuzenacAm.j Chem. Descrip. Platy talc... 

CAS 14807-96-6 EINECS/ELINCS 238-877-9 Uses Filler providing superior impact str. in polyolefins, exc. stability to gel coats, suitable in automotive, nucleation, and paint industry applies. Properties Powd. 1.4 median diam. fineness (Hegman) 7.0 sp.gr. 2.8 dens. 18.9 Ib/ff (tapped) bulking value 23.3 Ib/gal surf, area 14 m7 g oil absorp. 54 TAPPI brightness 92 pH 9.5 (10% slurry) Cimpact 710 [LuzenacAm.j Chem. Descrip. Platy talc... 

Chem. Descrip. Microcryst. platy talc CAS 14807-96-6 EINECS/ELINCS 238-877-9 Uses Filler for coatings, adhesives, and sealants Properties 6.5 p median particle size fineness (Hegman) 3.5 oil absorp. 33-37 brightness (GE) 83-87 Mistron 403 [LuzenacAm.j Chem. Descrip. Platy talc CAS 14807-96-6 EINECS/ELINCS 238-877-9 Uses Filler for coatings, adhesives, and sealants Properties 5.2 p median particle size fineness (Hegman) 4.0 oil absorp. 29-33 g/100 g brightness (GE) 84-88 Mistron 554 [LuzenacAm.j... 

Chem. Descrip. Microcryst. platy talc CAS 14807-96-6 EINECS/ELINCS 238-877-9 Uses Filler for coatings, adhesives, and sealants Properties 3.8 p median particle size fineness (Hegman) 5.5 oil absorp. 38-42 brightness (GE) 85-89 Mistron 604AV [LuzenacAm.j... 

Chem. Descrip. Platy talc CAS 14807-96-6 EINECS/ELINCS 238-877-9 Uses Filler for antiblocking and Industrial coatings dusting agent for non-stalnlng rubber applies. 

Synonyms Cl 77019 Cl 77718 Cosmetic talc Erench chalk Hydrous magnesium calcium silicate Hydrous magnesium silicate Industrial talc Magnesium hydrogen metasilicate Pigment white 26 Platy talc Talcum... 

Talc. Talc is httle used in rubber applications. Platy talcs are hydrophobic, white, alkaline, and of high particulate asymmetry. They are readily treated with silanes and other coupling agents. Unfortunately, particles of talc are generally too large for effective elastomer reinforcement. Nevertheless, talcs can be micronized to reduce median particle sizes to 1000 to 2000 inn. Such products are used but compete with less expensive clays. 

Talc loses its water of hydration at 1000°C. At this temperature, the talc crystal restructures itself to form the mineral enstatite (MgSiOs), which is significantly harder than talc, with a Mohs hardness of 5-6, and less platy. Talc is inert to most chemicals. It normally will absorb an equilibrium 0.2-0.3% by weight of moisture under normal atmospheric conditions. 

A typical construction involves a combination system employing a butyl mastic as the barrier sealant between the metal spacer and glass and a back-up, chemically curing sealant serving as an adhesive to hold the unit together. An insulated glass mastic formulation is shown in Table 14. Vistanex LM low molecular weight PIB is combined with a platy talc filler... 

High performance elastomeric butyl tapes are available for large window lite glazing in high-rise structures and for windshield sealing. These usually contain crosslinked butyl elastomers (20-40%) plus poly butenes, resinous tackifiers, and reinforcing fillers such as carbon black and platy talc. Chlorobutyl rubber compositions are available for faster and more thorough vulcanization. 

Platy talc - This is distinctly lamellar, soft talc, typically of >90% purity naturally or through beneficiation, which is used in cosmetic, pharmaceutical, and reinforcing filler applications. 

Roofing - Low-cost, off-color platy talc is used in roofing felts to add weight for lower cost per ft, to provide UV protection, to prevent oil penetration and migration, and to increase fire resistance. 

Plastics - Platy talc is used for reinforcing and/or filling both thermosets and thermoplastics, although principally the latter. Talc is used in thermoplastics to control melt flow, reduce creep in molded parts, increase molding cycles, increase heat deflection temperature, and improve dimensional stability. The... 

Ultrafine particle size platy talcs have been used extensively as recycling additives. The highly adsorbant talcs attract inks, adhesives and other organics that may be part of the recycled stock. Talcs also function in flotation deinking processes as foam stabilizers, and since talc tends to float on water, it helps to carry the ink particles to the surface. The talc-waste particles are large enough to be easily removed by filtration or other cleaning methods. 

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