11. Materials: aluminum and PET

Rules on PET bottles

• Should contain 25% recycled content

• Recycled content should come from EU

• This starts 21 november 2027

• You can include recyled content from outside the EU, but does not count towards 25%

What is PET made up of?

• Terephthalic acid (TPA or PTA)

• Ethylene Glycol (MEG or EG)

• Combined with heat and pressure creates PET

• The combination makes sure it is not too brittle

Why is PET popular?

• Transparant

• Light weight

• Strong

• Safe

• Recyclable

• Good barrier properties

• Versatile

• Environment safe

• PET (or polyester) is used in synthetic fibers, trays and packaging

How to produce a bottle?

• ISBM = Injection stretch blowmoulding (2 step)

1. Injection of a preform

2. Blowing of a bottle (happens at factories e.g. unilever they receive preform from a different factory)

Glass transition temperature PET?

• Tg for PET is 70-75 degrees Celsius.

• Tg marks temperature platform - rubbery phase - where PET can be formed.

PET stretch blow - molding

Within Tg platform - rubbery phase - PET (preform) is ready for stretch-blow moulding process

Why is stretching of PET necessary?

• Use PET efficiently

• Makes it stronger

• Allows polymers to organize and stretch (before is spaghetti and afterwards organized)

Steps in blow molding

1. Axial stretching

2. Axial and radial stretching

3. Radial stretching

Allows polymers to organize and stretch = gives the containers strength and heat-resistance (sometimes necessary for vacuum and high-process temperatures)

PET and shelf life

• Different barrier options in the PET tool-kit

• Also cap should have a good seal otherwise CO₂ might get lost

Mono layer vs multi layer

• Monolayer = blend of PET and barrier polymer active barriers (~3 months shelf life)

• Multilayer = sandwiched layer of high gas barrier polymer active or passive options (~9 months shelf life)

• Depends on how much CO₂ loss they will accept

Rules mixing materials 2030

• Monolayer cannot be two different plastics because than they cannot be separated anymore

• Therefore mono layers should consist of one material

• If you want more materials you should make a bottle with a multilayer

Bottle to bottle closed loop recyling

Difference in PET separation between countries

• France has bottle return system “statiegeld” which Great Britain does not

• Therefore in France it is well separated and GB contains a lot of other waste too

pakPET

• New technology where bottles are recycled back to flakes

• Bottles are then made out of 70% vPET and 30%rPET

What are things that need to be taken into consideration when making PET packaging?

• Food filling

  • Food can be filled cold or hot

  • Differences in filling techniques

PET hot fill process

• Standard hot fill temperature for juices is 85 degrees C

  • Extra strength (crystallinity) required to withstand > Tg temperature

• Special blowing technique; hot blow-mould

• Vacuum-resistant packaging required for cooling down

  • Controlled absorption of vacuum through base design and panels

• Hot fill temperatures for food > higher temperatures

  • More crystallinity required

  • More vacuum absorption required

Glass vs. PET in terms of carbon footprint

A PET jar has half the carbon footprint of its glass equivalent

Metal as a packaging material

• Steel

• Contains tin plate layer (usually for food cans)

• aluminium (all beverage cans are now aluminium)

Why is aluminum used?

• infinitely recyclable

• Perfect barrier against light and oxygen

Steps from coil to can

1. Metal coil is added (looks like toilet roll)

2. Bottom of can is created

3. Bottom of can is attached to top and is slid through circles that extend the can.

4. Excess can is cut off

5. UV rim coating

6. Printing on can

7. Inside coating

8. Neck has to be specific size to ensure standard size

   1. Often takes multiple steps to prevent aluminium from breaking

9. Cans are packaged on pellets.

Steps from coil to can end

• is done 24/7

• 10 billion units in one factory, between 600000 and 700000 per hour

• colored coils as starting material

• re-closable has not really been accepted

• can end and can body separately shipped to the customers

1. Ends are cut out

2. Ends are curled

3. A type of glue or compound is added that allows the can end to be attached to the can

4. Can tab is added to lid

Process of printing on can

First is printed on sheet color by color and then this sheet is put on the can

• Currently on the outside htere is a lot of BPA - everywhere there is color there is BPA

• this will have to go in the near future