Lecture 11 : Case study on plastic and paper packaging

Question 1

What are the 2 main rules / documents that define sustainable packaging? Define them.

Answer 1

1) The guideline
- confirmed attributes that define the way packaging is designed today and in the future to ensure it’s recyclability

2) The negative list
- list of materials, additives, packaging concepts and items which are / will be considered obsolete based on evolution of recycling technologies, infrastructure and legal/regulatory frameworks

Question 2

According to the guideline, what are the 10 rules of sustainable packaging design?

Big picture -> small details ;; from manufacturing packaging, RECYCLING, sale, consumer end

Answer 2

1) Improve overall sustatianbility by eliminating unncessary packaging.

2) Optimise primary, secondary and transport packaging → optimise space used when packaging primary packages for transport (≥95% pallet footprint, ≥ 90% cube use)

3) Eliminate excessive headspace in packaging

4) Increase recycling value for packaging that are recycled at scale

5) Maximise recycled content in plastic packaging when compliant (w safety → EU 2022/1616)

6) Improve environmental performance for B2B packaging

7) Follow industry standards for design for recycling, where the product is marketed

8) Consider infrastructure for collection, sorting and recycling

9) Meet market regulations in order to sell packaging in the market

10) Educate consumers → e.g. disposal instructions / QR codes

Question 3

Name 2 plastic materials on the negative list.

Answer 3

PVC
Polystyrene
PVDC (nvr learnt)

Question 4

What are oxo-degradable plastics and why should they not be used?

Answer 4

Oxo degradable plastics are regular plastics with additives that accelerate their breakdown into smaller pieces upon exposure to light/heat/oxygen. (Do not break down at the molecular / polymer level (chemically), physically break down into smaller pieces)

They should not be used as they breakdown into microplastics that are not truly biodegradable / recyclable

Question 5

Flexible plastic packaging

The goal for flexible plastic packaging is to maximise the usage of what plastics to facilitate recycling?

Answer 5

Mono PE / PP (>90%)

Question 6

Flexible plastic packaging - PRIMARY packaging

What are some material guidelines for flexible plastic packaging as a primary food packaging?

Answer 6

1. Use at least 90% mono PE/PP in structure.
2. Polyolefin can be used but with PE / PP > 90%. But favour mono PE/PP whenever possible
3. Dont use mono PET when possible
4. Use of OPA (oriented polyamide) / cast polyamide (CPA) is not reccomended
5. Phase out non-recyclable multi-material structures and incompatible plastic combinations

Question 7

Flexible plastic packaging - PRIMARY packaging

Why is mono PET not recommended for flexible plastic packaging, as opposed to mono PP/PE?

Answer 7

• PET is more rigid (polar ester groups), leading to stronger intermolecular bonds between polymer chains and thus is not suitable for flexible packaging.

Note : i thought PET have poorer barrier properties because it has polar ester groups = more permeable. But it has better oxygen and gas barrier, because it is more rigid…

Question 8

Flexible plastic packaging - PRIMARY packaging

Why is OPA / CPA (polyamide) not recommended for flexible plastic packaging?

Answer 8

Polyamides are often blended with other polymers, fillers, or additives to achieve specific properties, making them difficult to separate and recycle cleanly.

Question 9

Flexible plastic packaging - PRIMARY packaging

Give an example on Mono-PP structure for flexible primary packaging.

Answer 9

BOPP // (V) MOPP // CPP
- Note : (V) indicates layer is combined with EVOH

Recall :
cast PP → direct extrusion → heat-sealing layer, most flexible

Oriented PP (BOPP and MOPP) : polymer chains are stretched and aligned in a certain direction, making them more rigid and improving their barrier properties

BOPP : oriented in BOTH machine and traverse direction ;; MOPP : orintened in machine direction only

Question 10

Flexible plastic packaging - PRIMARY packaging

Give an example on Mono-PE structure for flexible primary packaging.

Answer 10

BOPE//(V)MPE//LLDPE

BOPE : biaxially oritented PE
(V)MPE : biaxially oritented PE
LLDPE : linear low density PE → more branching and lower density → weaker bonding between polymer chains → flexible ;; heat-sealing layer

Question 11

Flexible plastic packaging - PRIMARY packaging

Give an example on PO (polyolefin) structure for flexible primary packaging.

Answer 11

BOPP // (V) MOPP // LLDPE
- barrier is sufficient for most applications

LLDPE = low density and more branched, v flexible and good as heat sealing layer

Question 12

Flexible plastic packaging - PRIMARY packaging

State the disadvantage of mono PE as a flexible food packaging.

Answer 12

Mono PE cannot be used as high-barrier applications
- Note : surface energy of PE is low, cannot have homogenous metallisation also, thus barrier is poor

**Note : water and gas barrier is poor (recall : chain mobility, crystalline vs amorphous domain etc) **

Question 13

Flexible plastic packaging - PRIMARY packaging

What is the limitation of mono materials for plastic packaging

Answer 13

Many applications still need aluminium as the barrier layer, which cannot be replaced. (Even metallised film cannot provide such a high barrier)
- This affects recyclability of packaging (need resin and bonding layers to glue layers together, hard to separate)

Question 14

Flexible plastic packaging - SECONDARY packaging

Name the type of flexible plastic packaging that is typically used for secondary packaging

Hint : shrinks tightly around grouped products when heat is applied

Answer 14

(Hot) shrink wrap

Question 15

Flexible plastic packaging - SECONDARY packaging

What are some guidelines for using shrink wraps as secondary packaging? [5]

Answer 15

1) Eliminate whenever possible

2) Enhance recyclability by using mono PP / PE films and maximise recycled content

3) Use unlaminated films to enhance recyclability

4) Do not print on film, or minimise print area if needed

5) Avoid stickers / labels on film, but if necessary, labels should be same material as the film to facilitate recycling

Most impt : elimination ;; if not consider materials to use in film which affects recyclability ;; and finally any decorations

Question 16

Flexible plastic packaging - SECONDARY packaging

What is the difference between shrink film and stretch film?

Answer 16

Shrink film : a film that shrinks tightly around products when heat is applied, forming a tight seal
- common for drinks that come in a carton

Stretch film : flexible plastic that is stretched around objects to hold them together

Question 17

Flexible plastic packaging - SECONDARY packaging

What material is hot shrink film and stretch film mainly composed of?

Answer 17

Hot shrink film : LDPE / LLDPE

Stretch film : LLDPE

Need to stretch and wrap / shrink → need to be very flexible

Question 18

Flexible plastic packaging - SECONDARY packaging

How to increase sustainability of stretch films and shrink films? [3]

Answer 18

1. Reduce thickness of film
2. Adding recycled contents (starting from 30% for shrink film)
3. Evaluate thickness reduction + proportion of recycled content by testing data and real transportation trials to proove effectiveness

Question 19

Flexible plastic packaging - packaging production

How does a vertical form fill seal (FFS) machine work?

Answer 19

1) A roll of flexible film is unwind

2) Package forming : the film is passed through a forming collar and is bent and shaped around a vertical tube

3) Vertical sealing : he vertical edges of the film are sealed vaertically

4) Product dispensing : the product is dispensed into the packaging through the fill tube

5) Horizontal sealing : the top seal and bottom seal of the next bag is created simultaneously.

6) Individual packages are formed

Question 20

Flexible plastic packaging - packaging production

What kinds of packaging formats does a vertical FFS machine form?

Answer 20

1. Sachets
2. Stickpack
3. Guesseted
4. Block bottom
5. Pillow

Can refer to lect notes

Question 21

Flexible plastic packaging - packaging production

How does a horizontal form fill seal machine work?

Answer 21

1) Film is unwind and travels up a conveyor belt.

2) Food product comes in from another conveuor belt and slides onto the plastic film.

3) The sides of the plastic packaging is folded in, forming a tube

4) The top of the packaging is sealed (longitudinal seal)

5) The 2 sides are then sealed together (traverse seal)

Question 22

Flexible plastic packaging - packaging production

What is an important mechanical property for processability of plastic in the vertical / horizontal FFS machine?

Answer 22

Coefficient of friction

Question 23

Flexible plastic packaging - packaging production

What happens if Coefficient Of Friction (COF) is too high?

Think internal-internal (plastic layer-plastic layer), external-internal (machine part-plastic)

Answer 23

Too much friction
- Internal-internal : causes problems for heat sealing and the plastic layers cannot be heat sealed properly, causing machine to jam.

• Internal-external : for example, in the vertical FFS machine, the plastic material will stick onto the machinery (@ forming collar), leading to poor flow and jamming of the machine

Question 24

Flexible plastic packaging - packaging production

What happens if Coefficient Of Friction (COF) is too low?

Answer 24

Internal-external : for example, in the vertical FFS machine, the plastic will slide easily at the forming collar, causing the film to shift and misalign during forming → misaligned packaging / inaccurate sealing

Question 25

# **Rigid plastic packaging** What materials are usually used for rigid packaging? [3]

Answer 25

1. Mono PE 2. Mono PP 3. Mono PET

Question 26

# **Rigid plastic packaging** Rigid plastic packaging should aim EVOH at <__%?

Answer 26

6

Question 27

# **Rigid plastic packaging** What is carbon black used for in rigid food packaging, and why shouldn't it be used?

Answer 27

Carbon black is used as a dark pigment in packaging materials to make them black in colour, particularly for UV-blocking food packaging. - Should not be used as it prevents food packaging from being detected in automated sorters during recycling.

Question 28

# **Rigid food packaging** For rigid plastic packaging such as bottles, shrink sleeves are commonly applied. What are some aspects of shrink sleeves to take note of such that it is not problematic for recycling? [4]

Answer 28

1. Material choice 2. Adhesive choice 3. Inks 4. Size of sleeve

Question 29

# **Rigid food packaging** Currently, what kind of material is used for shrink sleeves on plastic bottles and why should it not be used?

Answer 29

PET-G (excellent combination of strength, clarity, and shrinking capabilities) - it is a source of contamination in PET recycling streams as PET-G requires higher processing temperatures to melt etc, thus it serves as a source of contamination and reduces the quality and value of recycled PET

Question 30

# **Rigid food packaging** What materials for PET sleeves are highly recommended?

Answer 30

Crystalline PET / polyolefins

Question 31

# **Rigid food packaging** What kinds of fillers should not be used in rigid packaging?

Answer 31

Fillers that increase plastic density to > 1g/cm³ - If such fillers are used in mono PE/PP, it cannot be separated from PET via float and sink anymore.

Question 32

# **Paper and paperboard - paper straws and wraps** Paper made from ____ must be used on all kinds of paper straws and wraps.

Answer 32

Virgin pulp (has not been previously used ;; aka NOT recycled, new)

Question 33

# **Paper and paperboard - paper straws and wraps** Why is it important to communicate to consumers that paper straws should be pushed back into tetra pak before disposal?

Answer 33

So that the whole packaging can be recycled together and processed together in the recycling stream, maximising efficiency

Question 34

# **Paper and paperboard - paper straws and wraps** Printings / inks are allowed on paper straws. True or False?

Answer 34

False. It can cause contamination and concerns to human health.

Question 35

# **Paper and paperboard - dispersion & extrusion coated** What kind of packaging material is dispersion/extrusion coated or laaminated paper and paperboard used in?

Answer 35

Multi-layer packaging such as tetra pak

Question 36

# **Paper and paperboard - dispersion & extrusion coated** How to ensure sustainability of dispersion / extrusion coated and laminated paper / paperboard? [3]

Answer 36

1. Maximise fibre content in packaging material, minimise content of polymers 2. Ensure efficient re-pulpability of fibre fraction and ease of delaimination 3. Guarantee successful testing and approval for recycling along with the OCC (old corrugated cardboard) and/or mixed paper waste

Question 37

# **Paper and paperboard - moulded pulp containers** Additives for wetting strength and additives CANNOT be added to moulded pulp containers. True or false?

Answer 37

False, can be added at low levels such that it does not affect pack recyclability

Question 38

# **Paper and paperboard - moulded pulp containers** Molded pulp containers made from non-wood pulp can always be recycled in the same stream as regular paper. True or false

Answer 38

False. You must confirm local recyclability and the correct stream, especially if non-wood pulp is used.

Question 39

# **Paper and paperboard - moulded pulp containers** What consumer-related guidance should be provided for molded pulp containers?

Answer 39

Clear instructions on removing food residues before disposal, to ensure efficient recycling.

Question 40

# **Multi-layer packaging - tetrapak** What are the 6 layers in tetra pak? ## Footnote * Recall from prev prof lect

Answer 40

1) Polyethylene **(outermost layer)** – protects against outside moisture (outermost layer) 2) Paper (extrusion/disperson coated or laminated paper) – layer for strength and structure 3) Polyethylene containing –COOH : adhesion layer between paper and aluminium ethylene copolymerised w monomer w COOH group 4) Aluminium foil – oxygen, flavour and light barrier 5) Polyethylene containing – COOH : strong bonding with aluminium 6) Polyethylene – heat-sealing layer (innermost layer)

Question 41

# **Decorations on packaging materials - inks, dyes & adhesives** What does a holistic end of life evaluation involve?

Answer 41

It involves evaluation of decorations together with the container it decorates. These decorations must be 1. easily separable from container OR 2. fully compatible with recycling stream of container

Question 42

# **Decorations on packaging materials - inks, dyes & adhesives** What are some guidelines regarding printing on packaging materials?

Answer 42

1. Do not print directly on PET bottles (but can consider for PP, PE, PET containers, trays, lid and pots) 2. Minimise print

Question 42

# **Decorations on packaging materials - inks, dyes & adhesives** What kinds of film materials / substrates should not be used for sleeves or labels? [2]

Answer 42

1. PVC 2. PET-G

Question 43

# **Decorations on packaging materials - inks, dyes & adhesives** For PE/PP container, the labels/ stickers / sleeve should be made of what material to ensure full recyclability? What label should be phased out?

Answer 43

Polyolefin - Paper label to be phased out unless proven not to disturb recycling

Question 44

# **Decorations on packaging materials - inks, dyes & adhesives** What is a guideline for labels/wrap around/stickers to ensure recyclability?

Answer 44

Labels/stickers should have a density of < 1g/cm³ - So that it can be separated from PET bottle via sink and float

Question 45

# **Decorations on packaging materials - inks, dyes & adhesives** What kinds of adhesives should not be used?

Answer 45

Non water soluble / dispersible adhesives - Adhesives must be soluble or dispersible in water to separate different layers for recycling

Question 45

# **Decorations on packaging materials - inks, dyes & adhesives** How does the approach to printing and recycling differ between the EU and US for packaging materials? (APR qualifiable washable ink system)

Answer 45

For EU - Printing with ink should be done on a separate sleeve, and ensure sleeve can be easily separated for recycling, because EU recycles the washing water US - Printing with washable ink can be considered (PET/PP/PE containers or trays) since new water is used to wash each batch of packaging material

Question 45

# **Decorations on packaging materials - inks, dyes & adhesives** Full sleeve designs (sleeve cover the whole bottle) should be limited to what kinds of applications?

Answer 45

Functional applications such as light barrier (must be proven to not disrupt recycling) - Sleeves for design purposes must be ruled out