Antiblock silicas

Table 19.9 Major suppliers/manufacturers of antiblock silicas. ...

Gasil - antiblocking silicas at http / / www. ineossilicas.com/index2.asp. 

Major suppliers/manufacturers of MgO are given in Table 20.2. Major suppliers/ manufacturers of hydrotalcites are given in Table 20.3. Major suppliers/manufacturers of fumed silica are covered along with antiblock silicas in Table 19.9. 

Additives used in final products Plasticizers poly(1,3-butylene glycol adipate) (Drapex 429), polyester sebacate (Paraplex G-25), octyl adipate Antistatic hydroxyethyl cellulose Antiblocking silica Release fluoro-chemical, microcystalline wax, polyethylene wax, silicone Slip alumina, magnesium stearate, polyethylene wax, silica ... 

Additives used in final products Fillers aluminum hydroxide, calcium carbonate, carbon black, graphite, mst protection fillers, zinc oxide Plasticizers biphenyl, dibutyl sebacate, diglycidyl ether of bisphenol A, dihexyl adipate, hexyl cyclohexyl adipate, polyethylene glycol, tetraethylene glycol di-n-heptanoate, triethylene glycol di-(2-ethylhexanoate) Antistatics antimony-doped tin oxide, vanadium pentoxide Antiblocking silica Release liquid paraffin, n-butyl stearate, silicone ... 

Figure 5.4. Effect of antiblocking silica agent on block force for polyethylene films containing 0.1% of stearamide or oleamide. [Data from Home, S. E. Suarez, J. I, SPEJ., 25,11,34-8, 1969.]...

The effect of antiblocking silica on thermal stabilizer is the only case described in literature which demonstrates the potential that the additives discussed in this book may inadvertly influence properties of products containing them. Figure 8.4 shows that in the presence of siUca A, thermal stability of film is lower compared to a control which did not contain silica, but contains HALS (Chimassorb 944). Replacement of sihea A by silica B results in further improvement of stabilization, which is due to the stabilizing action of silica combined with the stabilizing effect of HALS. 

Antiblocking silica used in polyethylenes and polypropylenes also improves scratch resistance of their films.Figure 10.5 compares effect of several additives on scrateh resistance. The effect is measured by changes in haze of films, which were slided against each other imder load. Figure 10.5 shows that new silica and talc give the best performance. " ... 

Antiblock additives are often incorporated into packaging films to prevent them sticking together. Their effectiveness relates directly to the roughness they impart on a film surface while minimising loss in optical properties. They are often used in association with slip additives such as erucamide. Common antiblock additives include crystalline silica, diatomaceous earth and talc (magnesium silicate). 

Antiblock agents like talc, chalk or silica can be used in form of masterbatches [23, 25]. The antiblock batches for processing Ecoflex and Ecovio are sold by BASF under the name Ecoflex Batch AB 1 or AB 3. 

Example 1 Film extrusion on blown film line. Antiblock agents like masterbatches of talc, chalk or silica (e.g., Ecoflex Batch AB 1) can be used for Ecoflex and Ecovio . The recommended level is higher than for polyolefins, e.g., 1 % of antiblock agent. If Ecovio compounds are processed, an antiblock agent in most cases is not needed for Ecovio F Film and Ecovio E Blend, because PLA acts as antiblock agent in higher quantities. 

Fine silica particles are incorporated in the surface of plastic films to prevent the adhesion of two sheets in contact with one another. The application is called antiblocking. The relatively low refractive index of the silica particles makes them more difficult to detect. 

There are at least five types of synthetic silicas that can be considered for use in polymers. These are generally known as fumed, arc, fused, gel and precipitated. A detailed review of their production and uses has been given by Watson [96]. The types most often encountered in thermoplastics are the gel and precipitated silicas which are frequently used as antiblocking agents in polymer films and as gloss reducing agents in polymer sheets. 

Antiblocking agents, slip additives Silica, amide waxes, oleamide... 

The Dylux 503 formulation contained a HABI, the leucodye TLA-454, a mixture of quinones, triethanolamine triacetate, several plasticizers, an organic acid, cellulose acetate butyrate binders, as well as antiblocking agents (fluorinated derivatives) as well as a silica derivative to provide tooth to the coating. The selection was made to provide maximum performance at minimum mill cost. The paper substrate required had high holdout, so as to permit two-sided coatings as well as to minimize the wicking of chemistry into the base. 

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. 

Polyethylenes are susceptible to oxidative degradation at processing temperatures, therefore antioxidants are added. Silica is sometimes added to LDPE as an antiblock to prevent films sticking and N,N-bis(2-hydroxyethyl)alkyl(C8-C18) amine (BEA) as an additive to reduce a build up of static charge (antistat). Table 10.2 gives commonly used substances in polyethylenes. 

FK 140, 150, 300DS, 310, 320, 320DS, 500LS. [Degussa] Silica or precipitated silica fw silicone rubber, paper and film industries antiblocking agent f(x polyolefins. 

Sipemat . [Degussa] Silica adsorbent anticaking and freeflow agents, carrier antiblock for films. 

Aerosn . [Dq st Degussa AG] Silica and fumi silica anticaking a firee-flow agent with high abscnption capacity teinfotcer, thickener for sili ne mbber industry antiblock fw I, PP and PE films and upes. 

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