Extrusion International 4-2024

28 Extrusion International 4/2024 MONOLAYERVERSION – PE evoh 6 Adhesive EVOH 4-LAYER VERSION PE/GLUE/EVOH/GLUE PP or PE Adhesive Water permeation rate [g/(sqm*d] at 25°C and 100% rH Oxygen permeation rate [g/(sqm*d*bar] at 25°C and 50% rH Barriers – Comparison of Permeation Rates Steel Aluminium Glass PA 0.01 0.1 1 10 100 1’000 10’00 EVOH PA/PA-O PVDC PET PP-O Metallized PLA PP-O PE 100 10 1 0.1 0.01 1. Adsorption 2. Absorption 3. Diffusion 4. Desorption DIE, horizontal disassembly: 1-pushing screw 2-balleye screw EXTRUSION TOOLING PO 4 400 CR – A Flexible Cross Head System for Barrier Pipes up to 400 mm Why barrier pipes? Because the aim is to protect a medium which is either inside or outside the pipe against permeation of (toxically) substances like gas or liquid. P ermeation is the penetra - tion of a permeate such as liquid or gas or vapour thou a solid wall. Perme- ation is directly related to the concentration gradient of the permeate. Perme- ation can be measured and Permeation works through diffusion. The permeate will move from high concentra - tion to low concentration. Examples for barrier pipes are: Pipes for fuel transpor - tation – permeate if fuel. The outer PE jacket of pre-isolated pipe for district heating – permeate is oxygen which degrades the foam. Hot wa- ter pipe for floor heating – permeate is oxygen. Water transportation pipes – permeate are hydrocarbons from soil in urban or industrial areas can be contaminated by a number of toxic chemicals such as fuels, oil or hy - drocarbons. Standard Polyethylene – used for portable water transportation is not resistant against diffusion of this chemicals. The solution to avoid diffusion is to apply to the stan - dard PE pipe a barrier layer based on plastic or non-plas- tic. Pipes with barrier materials based on non-perme- able polymer, leads to a durable, fully-recyclable long living barrier pipe solution. PE pipes with barrier layer have to fulfil EN 12201-3. Following barrier material are in use: EVOH, PVDC, PA, PET, O-PET, OPP and others. The barrier polymer se- lection depends on permeate. There are also non polymer barrier materials in use. Talcum increases the diffusion path and reduce perme - ability. Aluminium is a non-plastic 100% barrier material hav- ing following disadv ntages: • Aluminium tape – coated with glue – is more expen- sive than plastic barrier material, butt welding of pipes is difficult especially for fittings and elbows. • Coating process technology is more complicated. • Higher investment in case of a new extrusion line. • To convert existing line very complicated – wrapping unit and heating, scrap is contaminated with aluminium and difficult to recycle. Process technology Basically we have 3 options to make barrier pipes: Option 1: barrier pipe production with multilayer head: The basic pipe as well the ba rier layer is produced all together in one extrusion head at same time. The num- MONOLAYERVERSION–PE 6 MONOLAYERVERSION–PE evoh 6 Adhe ive EVOH 4-LAYER VERSION PE/GLUE/EVOH/GLUE PP or PE Adhesive Water permeation rate [g/(sqm*d] at 25°C and 100% rH Oxygen permeation rate [g/(sqm*d*bar] at 25°C and 50% rH Barriers – Comparison of Permeation Rates Steel Aluminium Glass PA 0.01 0.1 1 10 100 1’000 10’000 EVOH PA/PA-O PVDC PET PP-O Metallized PLA PP-O PE 100 10 1 0.1 0.01 1. Adsorption 2. Absorption 3. Diffusion 4. Desorption DIE, horizontal disassembly: 1-pushing screw 2-balleye screw MONOLAYERVERSION–PE 6 Adhesive EVOH 4-LAYER VERSION PE/GLUE/EVOH/GLUE PP or PE Adhesive Water permeation rate [g/(sqm*d] at 25°C and 100% rH Oxygen permeation rate [g/(sqm*d*bar] at 25°C and 50% rH Barriers – Comparison of Permeation Rates Steel Aluminium Glass PA 0.01 0.1 1 10 100 1’000 10’000 EVOH PA/PA-O PVDC PET PP-O Metallized PLA PP-O PE 100 10 1 0.1 0.01 1. Adsorption 2. Absorption 3. Diffusion 4. Desorption DIE, horizontal disassembly: 1-pushing screw 2-balleye screw Mandrel, horizontal disassembly 1-lift arm mandrel connection 2-eyeball screw