Irgafos 168 stabilizer

Thermal and Oxidative Stability. In general, polyolefins undergo thermal transitions at much lower temperatures than condensation polymers thus, the thermal and oxidative stability of polyolefin fibers are comparatively poor. Preferred stabilizers are highly substituted phenols such as Cyanox 1790 and lrganox 1010, or phosphites such as Ultranox 626 and Irgafos 168. 

Haider and Karlsson [15] developed a simple procedure for the determination of aromatic antioxidants and ultraviolet stabilizers in polyethylene using ultrasonic extraction. Chloroform was used for the isolation of Chi-massorb 944 from 150-pm-thick commerical low-density polyethylene and Irganox 1010 and Irgafos 168 from 25-pm medium-density polyethylene film. The recovery of the additives increased remarkably at higher temperatures and longer extraction times. At 60°C, quantitative recovery was achieved in 15, 45, and 60 minutes for Irgafos 168, Irganox 1010, and Chi-massorb 944, respectively. 

The isothermal measurement under oxygen showed good correlations between chemiluminescence parameters and the concentration of stabilizers. The oxidation induction times have been seen to increase with the ratio of Irgafos 168/Irganox 1330 (Fig. 3.10). In general, the OITs increased with the transition temperature determined... 

Irgafos . [Ciba-Geigy/Additives] Phosphite heat stabilizer, antioxidant for polyolefins. 

Figure 16.6. Stabilization of polypropylene with Irganox 1010 antioxidant (AO) and Irgafos 168 phosphite (Ph). The total amount of stabilizers was kept constant at 0.1 wt%. The data show variation of the melt flow rate (MFR) measured at 230°C using 2.16 kg weight on the plunger. The lower (points) and upper (triangles) set of data show the MFR after one and flve extrusions at 280°C. Data [Zweifel, 1998].

Figure 16.8. Effects of addition of Irganox B225 (1 1 blend of Irganox 101 and Irgafos 168) on repetitively extruded (up to five times) HOPE. The stabilizer was added in the amount of 0, 0.05, and 0.20 wt%. After [Herbst et al., 1997],...

In packaging, three resins account for the majority of the market for antioxidants PP, PE, and HIPS. For PP, a combination of hindered phenol and phosphite antioxidants is commonly used, with the total concentration normally from 0.08 to 1%, depending on formulation and end use. Clba Specialty Chemicals has developed the phenolic antioxidant family of Irganox for use in PP and PE, and also the Irgafos family, which are phosphite stabilizers used in combination with phenolic antioxidants. For LDPE, BHT, a phenolic antioxidant, is normally incorporated at levels of 50 to 500 ppm however there is a tendency to employ less volatile additives to prevent their migration from the resin. For HDPE and LLDPE, antioxidants less volatile than BHT, such as polyphenols, at higher concentrations, are normally used In combination with phosphites. For HIPS, hindered phenols are used in combination with UV absorbers. Alpha-tocopherol (Vitamin E) is sometimes used as an antioxidant for polyolefins. 

In an article in 1998 examining new trends in stabilising additives. Solera [55] noted that, while phosphites are effective process stabilisers in PET, they can themselves be subject to hydrolytic degradation. A new phosphorus-based stabiliser with increased hydrolytic stability was suggested in the form of 2,2, 2 -nitrilo[triethyl-tris(3,3, 5,5 -tetra- -butyl-l,T-biphenyl-2,2 -diyl)]phosphite (Irgafos 12 Ciba). 

For environmental reasons, direct examination of polymers by spectroscopy and/or by non-destructive methods is preferred over solvent-consuming techniques.Poleunis et al. " reported the use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) to analyze additive migration toward polymer surface in thin films of amorphous polyester containing variable quantities of an antioxidant (Irgafos 168) and a UV stabilizer (Hostavin N30). The results obtained were promising, but authors stated that ToF-SlMS data can be compared quantitatively only if the surfaces have undergone identical treatments. 

A polyethylene resin stabilizer, Cyasorb LTV 1084 ([2,2 -thiobis(4-r-octylphenol-ato)]-n-butylamine Ni(Il)), and its degradation products were monitored using a C]g column (A — 285 nm) and a 94.5/5.0/0.5 IPA/water/acetic acid mobile phase [234], Ten other polymer additives (e.g., BHT, BHEB, UV 531, Isonox 129, Ethyl 330, Irgafos 168) were monitored as well. Elution times were reported and fell in the range 2-12 min. Concentration ranges of 10-500 mg/L were used. 

Peroxide Decomposers as Processing Stabiiizers. Alkyl and aryl phosphite esters (see Scheme 12) are effective melt stabilizers. They are often used in combination with hindered phenols (see Table 6). Phosphites generally function by a stoichiometric peroxidolytic mechanism (PD-S) Table 7 illustrates the benefits of using the commercial phosphites TNPP (AO 15) and Irgafos P-EPQ (AO 17, Table 3) for melt stabilization (95). The unique phosphite AO 37 and its phosphate transformation products AOs 38 and 39, (Table 7), which were shown (104,133-135) to operate by a catalytic mechanism (PD-C), are particularly effective at low concentration of the parent stabilizer molecule (see AO 37, Table 7) (95). Phosphites are, however, generally susceptible to hydrolysis. For example, hydrolysis of aryl phosphites leads to the formation of low molecular mass phenol and a... 

Fig. 8. Effect of molar composition of mixture of HALS and Irgafos 168 (total [AO] = 7 X 10 mol/kg in each case) on (a) extent of synergism and antagonism during photooxidation of PP (193), and (b) thermoxidative stability of PP in air oven (195).

Fig. 4 Average adhesion forces (nN) obtained with -CH3 and -OH terminated tips on stabilized polypropylene (0.05 wt % of Irganox 1010, 0.1 wt % of Irgafos 168 and 0.5 wt % of Tinuvin 770). The results are compared to adhesion forces obtained on polypropylene on which a film of T770 has been spin-coated. The force-distance curves were recorded in water or in nitrogen atmosphere.

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