BM1 Process

Extrusion Blow-Moulding: The Process

Dept. Polymer Engineering University of Minho

Applications

Dept. Polymer Engineering University of Minho

Extrusion based process Plasticising unit

Hopper

Extrusion die

Control panel Mould and clamping unit

Dept. Polymer Engineering University of Minho

Extrusion based process

Dept. Polymer Engineering University of Minho

Extrusion based process

Dept. Polymer Engineering University of Minho

Extrusion based process

Dept. Polymer Engineering University of Minho

Extrusion based process

Dept. Polymer Engineering University of Minho

Extrusion based process

Dept. Polymer Engineering University of Minho

Extrusion based process

Dept. Polymer Engineering University of Minho

Extrusion based process: extrusion heads

Dept. Polymer Engineering University of Minho

Extrusion based process: die centring

Dept. Polymer Engineering University of Minho

Extrusion based process: effect of sag and extrudate swell

1 - swell and no sag 2 - sag and no swell 3 – sag plus swell

Dept. Polymer Engineering University of Minho

Extrusion based process: axial parison thickness programming

Dept. Polymer Engineering University of Minho

Extrusion based process: axial parison thickness programming

Dept. Polymer Engineering University of Minho

Extrusion based process: effect of sag and extrudate swell

Dept. Polymer Engineering University of Minho

Extrusion based process: transversal parison thickness programming

Dept. Polymer Engineering University of Minho

Extrusion based process: extrusion with accumulator

For containers of high capacity (>12.5 l) Dept. Polymer Engineering University of Minho

Extrusion based process: moulds

Dept. Polymer Engineering University of Minho

Extrusion based process: moulds

Dept. Polymer Engineering University of Minho

Extrusion based process: moulds 4

Types of ventilation systems

1

3

2

Capacity (l) Slit depth (mm) >5 0.01-0.02 5-10 0.02-0.03 10-30 0.03-0.04 30-100 0.04-0.10 100-500 0.10-0.30 Dept. Polymer Engineering University of Minho

Extrusion based process: moulds

Pinch-off

Dept. Polymer Engineering University of Minho

Extrusion based process: moulds

Inflation with needle

Dept. Polymer Engineering University of Minho

Extrusion based process: moulds

Cooling system:

• Channels diameter (d): 6 ≤ d ≤ 20 mm • Length: as short as possible (Texit-Tentrance ≤5ºC) • Reduced number of curve zones • Distance channel-cavity surface: d • Distance between consecutive channels: 1.5 d

Dept. Polymer Engineering University of Minho

Extrusion based process: co-extrusion Permeability coefficients

HDPE Adhesive PA Recycled HDPE

Prices (relative to PVC)

Dept. Polymer Engineering University of Minho

Extrusion based process: co-extrusion

Dept. Polymer Engineering University of Minho

Injection moulding based process

Dept. Polymer Engineering University of Minho

Injection moulding based process

Dept. Polymer Engineering University of Minho

Injection moulding based process

Advantages

Disadvantages

Dept. Polymer Engineering University of Minho

Injection moulding based process: designing pre-forms

• Espessuras tão pequenas quanto possível • Razões de sopro elevadas • Machos cónicos (conicidade mínima de 0.5º) • Variações de espessura por maquinação da cavidade

• Machos cilíndricos • Variações de espessura por maquinação do macho

Dept. Polymer Engineering University of Minho

Injection moulding based process: sequence for designing pre-forms 1 – Desenho do contentor (conhecido) e do macho (diâmetro e inclinação conhecidos) 2 – Selecção das secções transversais a dimensionar 3 – Determinação da espessura da pré-forma (balanço mássico) nas secções seleccionadas no passo 2 4 – Representação das espessuras determinadas no passo 3 no desenho 5 – Atenuação de transições bruscas de espessura 6 – Cálculo do volume da pré-forma 7 – Repetição dos passos 5 e 6 até se obter um volume de préforma semelhante ao do contentor Dept. Polymer Engineering University of Minho

Stretch blow moulding Ejection of the bottle

Stretching and blowing

Injection moulding of the pre-form

Dept. Polymer Engineering University of Minho

Stretch blow moulding

Dept. Polymer Engineering University of Minho

Stretch blow moulding

Dept. Polymer Engineering University of Minho

Stretch blow moulding

Dept. Polymer Engineering University of Minho

Stretch blow moulding: sequence of stretch and blowing Blowing up without stretching

Wang et al., 1997 Dept. Polymer Engineering University of Minho

Stretch blow moulding: sequence of stretch and blowing Blowing after stretching

Blowing up while stretching

Wang et al., 1997 Dept. Polymer Engineering University of Minho

Stretch blow moulding: material bi-orientation

Dept. Polymer Engineering University of Minho

Stretch blow moulding: effect of orientation

Dept. Polymer Engineering University of Minho

Carbonated drinks: permeability (CO2) Maximise ratio volume / surface area

Geometry

Capacity

Dept. Polymer Engineering University of Minho

Stretch blow moulding: typical processing parameters

(Blow-up ratio) x (stretching ratio)

Dept. Polymer Engineering University of Minho

Stretch blow moulding: crystallisation kinetics

Glassy state

Rubbery state

Crystals cannot form: molecules are too sluggish

Melt state

Crystals cannot exist: molecules are too energetic Temperature (ºC) 250

60

255

65

Dept. Polymer Engineering University of Minho

Stretch blow moulding: PET typical heat cycle

Dept. Polymer Engineering University of Minho

Stretch blow moulding: moulds for two stages process

Dept. Polymer Engineering University of Minho

Stretch blow moulding: two stages versus one stage process

Advantages • Higher production rates • Better pre-form temperature control

Disadvantages

• Higher global energy consumption

• Simpler bottle production (no need of know-how on polymer processing )

Dept. Polymer Engineering University of Minho

Extrusion Blow-Moulding: Non-Conventional Techniques

Dept. Polymer Engineering University of Minho

Non-conventional techniques: 3D technique

Dept. Polymer Engineering University of Minho

Non-conventional techniques: 3D technique

Conventional

3D

Battenfeld Fischer Dept. Polymer Engineering University of Minho

3D Technique: X-Y mould

Cavity Parison

Blow mould

Placo, Ltd Dept. Polymer Engineering University of Minho

3D Technique: X-Y mould

Placo, Ltd Dept. Polymer Engineering University of Minho

3D Technique: mould with vacuum

Battenfeld Fischer Dept. Polymer Engineering University of Minho

Pre-blowing and moulds with moveable parts

Double walled container

Dept. Polymer Engineering University of Minho

Pre-blowing and moulds with moveable parts

Hollow container with re-entrant zone

Dept. Polymer Engineering University of Minho

Sequential co-extrusion Rigid Flexible Rigid

Cycle time Dept. Polymer Engineering University of Minho

Sequential co-extrusion

Extruder 1

Extruder 2

Accumulator 1

Accumulator 2

Die flow channel 1

Die flow channel 2

Single die lip

Battenfeld Fischer Dept. Polymer Engineering University of Minho

Pressblower process

Dept. Polymer Engineering University of Minho