100 likes | 317 Views
Blow Moulding Process & Barrier Containers Part 1.5 Effect of resin properties. Processing - Viscosity. The viscosity together with the lubrication (additives) determine: melt pressure melt fracture occurrence - bottle aesthetics. Processing – Influence of the resin.
E N D
Blow Moulding Process & Barrier Containers Part 1.5 Effect of resin properties
Processing - Viscosity • The viscosity together with the lubrication (additives) determine: • melt pressure • melt fracture occurrence • - bottle aesthetics
Processing – Influence of the resin • For an optimal processability and performance the type of grade used is important: • - rheology: processing, downgauging (swell) • solid state properties: • density • impact resistance • chemical resistance • environmental stress crack resistance • optical properties (gloss, clarity) • creep and bulging
Processing Swell Do: outer diameter of die Dp: diameter of parison ho: die gap hp: thickness of parison Dp/Do: diameter swell (BD) hp/ho : thickness swell (BH) Weight swell (BA)= BD x BH if diameter >> thickness
Processing: swell related problems The combination of high swell and low melt strength leads to curtaining (parison collapse) High Swell Narrow die gap Impuritysensitive High shear rates High diameter swell Die lines High hoop stress Excessive Flash Pleating Trimming problems Handle webbing
Relation between bottle and resin properties Property ESCR impact resistance Stiffness(Topload) Barrier prop. Density
Bottleproperty Gloss Impact resistance Abrasion resistance ESCR Relation between bottle and resin properties Melt Index
Pinch-off properties Property Parison drawdown (sagging) Effect of resin properties on processing Melt index
Property Bottle weight/ weight swell Output Pinch-off properties Gloss Melt temperature Effect of extrusion parameters on plastic variables