Factors affecting optimum stabilizer selection

The factors to consider in making an optimum stabilizer selection for a given vinyl process can be divided into three broad categories:

Formulation variables 

Such as PVC resin, impact modifier, processing aids, plasticizers, fillers, pigments, lubricants, foaming agents, and other miscellaneous ingredients can all have an effect upon or be affected by the stabilizer.

Process Variables

which can be a determinant in stabilizer selection include consideration of compounding procedures (Banbury, Dryblend, Plastisol Mixing), calendering, extrusion (single or twin screw), injection molding, blow molding, foamed vinyls ,and so on. Other considerations of processing include melt rheology, plastisol viscosity properties, plate-out, scrap re-work, etc.

End Use Properties 

that affect stabilizer selection include clarity, outdoor weathering, toxicity, stain resistance, impact strength, heat distortion, electrical properties, odor, effects of moisture, heat-sealing and printability, and “fogging” (automotive and food wrap film).

Ca-Zn based stabilizers

Ca-Zn based stabilizers are widely used in many flexible and rigid PVC applications. This type of stabilizing system can give products which have a high degree of clarity, good mechanical and electrical properties, excellent organoleptic properties and good outdoor weatherability. Ca-Zn based stabilizer systems have low toxicity or are regarded as non-toxic. There are no risks to human health or the environment arising from the use of zinc stearate in PVC heat stabilizers.

Pb-based stabilizers

Pb-based stabilizers do not decrease the mechanical properties of PVC and they exhibit low extraction values when incorporated in the PVC matrix. Therefore, Pb-based stabilizers are used to produce articles requiring good mechanical properties, e.g., high impact strength, high heat distortion temperatures, and no migration, such as pressure pipes, sewage pipes, drainage pipes, electrical conduit, gutters, sheets, boards, profiles for indoor and outdoor applications, and, especially, building profiles.

Impact of PVC Ingredients on Heat Stabilizers Selection

The best approach in most cases is to check heat stability and color retention of the formulation with and without these additives. It helps to pre-determine the extent of any potential problem.

Vinyl ingredients which can have a potential impact on PVC heat stability are discussed below:

Vinyl Resins

Modifying Resins

Plasticizers

Fillers

Pigments

Lubricants

Other Additives

Package and storage:

Packed in weaved bag, lined with a PE bag, 25kg in weight. 

It should be stored in cool and dry places with good ventilation. The expiring date is 12 months after the production date.