Antiblocking fillers

For plastic sheets/films, blocking is generally defined as a condition that occurs when two or more sheets/films stick together when stacked on top of one another. 

Two parameters, namely the particle size and the number of antiblock particles on the film surface, dominate the antiblocking effect, besides other factors such as type of film material. It has been shown that the higher the surface roughness (i.e., the more particles that there are on the surface) the better the antiblocking performance. 

In general, small particle size antiblocks are preferred for thin films (20-30pm), while coarse particles are employed for thick films ( 30(im). Agglomerates of antiblocks reduce the antiblocking performance [61]. The selection of the appropriate antiblock depends on the polymer type and the quality requirements of the final film product. 

Several inorganic fillers/organic additives, such as silica, talc, kaolin, CaC03, titania, zeolites, cross-linked acrylic copolymers, spherical silicon beads, and so on, are employed in the plastics/coatings industry to attain the desired blocking performance. Some of these fillers are discussed elsewhere in this book in terms of their primary function only amorphous silica forms (natural and synthetic), used for antiblocking, will therefore be discussed in this chapter. 

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Other inorganic antiblocking fillers such as calcium carbonate, alumina-silicate ceramic spheres, zeolite, kaolin day, feldspar, and mica have also been used as antiblocks. In PE film, caldum carbonate can provide the low blocking force of talc and DE, but only when loaded at 2-3 times their concentration (or higher), reducing darity of the film, and increasing its density [12-1, 12-22, 12-30]. 

Surface Property Modifiers with further division into a) solid lubricants/tribological additives that include molybdenite, graphite, PTFE and boron nitride and b) antiblocking fillers such as silica. Chapter 19. 

Some fine particle fillers, such as silica gel or chalk, called as antiblocking agents, can also be classified as external lubricants. They make the separation of rolled films easier. 

Talc - Talc is a filler made by dry or wet grinding of mineral magnesium silicate. Talc improves stiffness, dimensional stability, flexural modulus, creep resistance, flow, surface smoothness, moisture resistance, tensile strength, and wear resistance of plastics. It also increases heat deflection temperature and decreases vapor permeability. Can be used as a film antiblock agent. Used mainly in polypropylene but also in thermoplastic and unsaturated polyesters and epoxy resins at low levels. Surface-modified grades are available. 

Any additive is a potential source of change to the overall processability from pellet feed to melt rheology. The not uncommon operator comment that one particular color always runs well and another always causes problems is more likely to be fact than superstition. Many products are colored by using masterbatches. whilst extruded products may contain antiblock and slip additives. Injection moldings may contain lubricants to aid mold release or provide product lubrication, e,g., bottle caps. In many cases such nias-terbatches contain low-viscosity polymer waxes to promote additive dispersion (particularly pigments) and masterbatch distribution throughout the natural polymer. There are in fact many additives, including fillers, flame retardants, and antioxidants, that can influence processability. 

In judging the suitability of a common filler such as CaCOs as an antiblock in PO film applications, researchers have noted complicated relationships between... 

Aerosil 0X50 [Degussa/Aerosil Silanes Degussa AG/Aerosil Silanes] Chem. Descrip. Fumed silica CAS 112945-52-5 EINECS/ELINCS 231-545-4 Uses Filler for plastics, silicone rubber antiblocking agent for PET, PP and PE films and tapes for coating of elec, light bulbs Properties Wh. fluffy powd. 40 nm avg. particle size sp.gr. 2.2 dens. = 130 g/l surf, area 50 15 mTg pH 3.8-4.5 (4% aq. susp.) > 99.8% assay... 

CAS 12001-26-2 EINECS/ELINCS 310-127-6 Uses Filler for marine paints, wood stains, and industrial primers antiblock in mech. rubber goods... 

Uses Filler in tinishes, enamels, maintenance paints, plastic film antiblocks, urethane rubber, polishes, adhesives and sealants Properties Wh. tine powd. 100% thru 325 mesh 2.1 median particle size tineness (Hegman) 7 sp.gr. 2.65 dens. 22.07 Ib/gal surf, area 2.0 mVg oil absorp. 28 brightness 87.7 m.p. 1610 C ref. index 1.54-1.55 pH 6.4 hardness (Mohs) 6.5... 

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. 

Uses Filler for coatings (metal finishes, primers, interior/exterior architectural, marine, protective, maintenance), plastic film antiblocks, silicone rubber, adhesives... 

Chem. Descrip. Ethylene/vinyl laurate/vinyl chloride terpolymer with polyvinyl alcohol stabilizer and mineral filler antiblocking agent Uses Binder, water repellent in conjunction with inorg. binders in plasters. Joint mortars, troweling compds., tile and construction adhesives, adhesives for external insulation and finishing systems sole binder in plasters, paints, adhesives modifier, adhesion promoter, plasticizer, impact resist, aid for gypsum and anhydrite Features Imparts hydrophobic props. enhances adhesion, flex, str., plasticity, abrasion resist., and workability contains no soivs., plasticizers, of film-forming aids... 

Sparwite W-5HB Sparwite W-10 Sparwite W-10HB filler, antiblocking coatings Sllverllne 002 filler, anticorrosive coatings Sparwite W-10 Sparwite W-20 filler, anticorrosive paints MIcroblanc TMB filler, appliance coatings ASP 170... 

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