Coupling agents, zirconates

For silica fillers, hydrolytic stability is best when M = Si for other fillers, e.g., calcium carbonate then titanate- or zirconate-coupling agents are preferred. 

Other additives such as silanes, titanates and zirconates are also used to overcome the processing characteristics of silica fillers. Silanes not only give improved processability of silica-filled compounds, but also provide improved crosslinks between the silica particle surface and the rubber molecular chains giving increased physical properties. The use of silane coupling agents at a... 

Hunt et al. [ 17] have investigated the role of various coupling agents, such as zirconates, titanates, and zircoaluminates, in zirconia-polypropylene suspensions for use in the production of ceramics by injection moulding. All the coupling agents were observed to reduce the melt viscosity. 

S. J. Monte, Ken-React Reference Manual, Titanate, Zirconate andAluminate Coupling Agents, Kenrich Petrochemicals Inc., Bayonne, N.J., 1993. 

Zirconates Zirconate coupling agents have very similar structure to the titanates. They also perform similar functions. Zirconium compounds exist in both water and organic solvent soluble forms. Like the titanates, zirconate coupling agents are useful in improving the dispersion characteristics of fillers in polymer systems. Examples of zirconate coupling... 

TABLE 10.7 Common Zirconate Coupling Agents and Their Applications... 

KZ Series. [Kenrich Petrochemicals] Zirconates coupling agents. 

NZ Series. [Keniich Petrochemicals] Zirconates coupling agents adhesion promoters, antioxidants, antistats, accelerators, activatixs, catalysts, curatives, corrosion inhibitors, dispersants, emulsifiers, flame retardants, foamers, impact modifiers, release agents, retarders, stalnlizeis, etc. 

There are a variety of silanes, titanates and zirconates used as coupling agents for the reinforcing type of filler. 

Titanate and zirconate coupling agents have also been used to compatibilize PP and PE to aeate useful products that contain more recyclate For example, a titanate reportedly aeated a useful 80% LDPE, 20% PP regrind blend. 

Monte SJ. Titanate and zirconate coupling agents in foamed polymers, technical report. Kenrich Petrochemicals Inc. 

Monte SJ, Neoalkoxy titanate and zirconate coupling agent additives in thermoplastics. Rapra Technology. Polym Polym Compos 2002 10(1). 

Titanate coupling agents impart increased functionality to fillers in plastics. The different ways that these additives work in filled polymers can be explained by breaking down the various mechanisms of the titanate (or zirconate) molecule into six distinct functions. Filler pretreatment and in situ reactive compounding with titanates and zirconates to effect coupling, catalysis, and heteroatom functionality in the polymer melt are also discussed. 

Table 5.2 Titanate and zirconate coupling agents form designation.

Monte, S.J. (1995) Ken-React Reference Manual Titanate, Zirconate and Aluminate Coupling Agents, 3rd edn, Kenrich Petrochemicals, Inc., Bayonne, NJ. 

When choosing a coupling agent, the possibility of discoloration or of reaction with other additives such as stabilisers should be considered. Zirconates have a useful advantage over titanates in that they do not react with phenolic antioxidants to produce coloured substances. 

Ken-React NZ, Neoalkoxy zirconate Uquid coupling agents, Kenrich Petrochemicals, Inc. 

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