Lubricants heat stabilisers

Typical additive packages for engineering thermoplastics have been described by Titzschkau [9], such as processing aids for PA, PP, or PET/PBT, three-component additive packages for polyamides and polyesters (nucleating agent, lubricant and process heat stabiliser) and coated copper stabilisers for polyamides. Additive packages or combinations of up to five or more additives are quite common. A typical white window PVC profile formulation comprises an acrylic impact modifier, TiC>2, CaCC>3, calcium stearate, a... 

The main groups of additives have already been listed in Section 2. PVC formulation technology depends on the correct combination of several of these additives to suit the processing and end-use requirements. A basic rigid PVC-U formulation will contain medium to low molecular weight resin plus lubricant and heat stabiliser. Other additives will be included to improve processability and physical properties, give weathering resistance, improve cost performance, colour, etc. 

Printing on vinyl surfaces can be problematic due to the influence of the formulation ingredients, particularly heat stabilisers and lubricants, on print adhesion. Spectroscopic analysis of PVC-P films has identified the formation of a barium zinc stearate complex which formed in the PVC matrix and migrated to the surface (207). Polymeric plasticisers have been developed to increase the surface energy, and so improve print adhesion. The incorporation of stearic acid had a surface energy reducing effect when used with the polymeric plasticiser (193). 

The use is discussed of Sinstad multifunctional compositions for use in low-plasticised PVC pipe formulations as heat stabilisers and plasticisers. The research reported consisted mainly of investigating the physical and mechanical properties of the plastic compound, its ease of manufacture, and processing with partial replacement of the plasticiser and stabiliser and complete replacement of the lubricants. Properties of PVC compositions for the production of pipe connectors and pipes with varying formulations are discussed. 7 refs. (Article translated from Plasticheskie Massy, No. 11,2000, P-43)... 

Most PVC compoimds are made using one-pack additive systems that allow the addition of the heat stabiliser at the same time as the lubricant, the process aid, an impact modifier and titanium dioxide or another pigment. 

Reagens SpA offers an organic-based stabiliser called Reapak TU-1626 XO, while Chemson s Naftosafe one-pack organic stabilisers for PVC pipe incorporate an organic stabiliser, a costabiliser, an acid scavenger, and internal and external lubricants. Lamberti SpA has produced organic heat stabilisers based on amino uracils. 

Lubricants have to be compatible with the main heat stabiliser systems, otherwise their sales will obviously be severely restricted. Clariant s Licowax OP is described as suitable for either lead or mixed metal systems. 

Crompton has developed a combined lubricant and heat stabiliser, called Mark 2910, for extruded PVC pipe. The special feature of this liquid product is that profile extruders do not have to buy a separate lubricant such as paraffin wax and add it by a further metered operation. 

The market share held by PVC has a crucial effect on the sales of heat stabilisers, plasticisers and lubricants, and is fairly important for fillers as well. At present the demand situation looks healthy for rigid PVC, but growth remains poor in Europe for flexible grades. 

Typical TG-DTA applications are thermal and oxidative stability, determination of relative components, decomposition temperatures and thermal decay reactions, action of heat stabilisers, thermal ageing. TG-DTA has been used to screen candidate automotive engineering plastics, elastomeric seals and lubricant additives to establish quality and understand field failures [300], The organometallic chemicals used as lubricant additives were employed to increase the thermal and/or oxidative stability of passenger car and heavy-duty diesel oils. 

Other additives such as dyes, pigments, heat stabilisers and lubricants are also frequently added. 

Antiblock agents Antioxidants Antisplit agents Antistatic agents Heat stabilisers Lubricants... 

Plastics additives may be divided into two main categories —those which modify polymer properties by physical means, such as plasticisers, lubricants, impact modifiers, fillers, pigments, etc, and additives which achieve their effect by chemical reactions such as PVC heat stabilisers, antioxidants, ultraviolet absorbers and flame retardants. In selecting them, however, care must be taken to match the additives to the polymer they are intended to protect, taking into account such factors as compatibility, efficiency and possible synergism of two or more additives in the particular polymer under consideration. 

An additive system was developed for poly(vinyl chloride) for medical applications. The additives include primary stabilisers (Ca-Zn stearate and Zn stearate), secondary stabilisers (epoxides) and lubricants (ethylene bisamide and high density polyethylene), to improve melt processing and heat stability. The use of the stabilisers resulted in reduced equipment down-time, increased the level of recycled material which could be incorporated, and enhanced the product characteristics, including colour, clarity, blush, aqueous extractables and particle generation. 5 refs. 

---