PKSC 2040 test 3 - Flexible Packaging

What is the value of flexible packaging?

Uses less material, weighs less, is portable, and constant technological advancement closes the gap on the ridges

What are bags/pouches functions?

Contain, preserve, and transport

What are seals/fitments functions?

Preserve and protect

What are printing/labels functions?

Communicate and inform

What do lightweight materials do?

Save on transport but their robustness could be a problem

Converting process definition

transform raw materials in the form of polymer pellets or film substrates(including paper and foil) into a final packaging structure

Why is it hard to tell where the line is between semi-rigid or flexible?

Lots of flexible containers can stand up on their own and some semi-rigids have the same sealing mechanism as flexibles

What main packages are included under flexible?

Bags (coffee, sugar, bread)

Wrappers(candy bar {not often sealed})

Overwraps: candy bars, crackers, restaurant saltines

Pouches: (standup, 4 seal flat, 3 seal pillow)

What are less obvious types of flexible packaging?

Skin packages, lid/lidding, bands and labels, shrink/stretch wraps, and specialty shapes

What materials are used for flexible packaging?

Monolayers, coextrusions, and laminations (substrates and adhesives)

What are additional flexible packaging materials?

Fitments (spouts, closures) and reclosable features (zippers, velcro, pressure sensitive adhesives{oreo})

What are some common monolayer packages?

LDPE and OPP

What would LDPE monolayer packages be used for?

Bags used for containment or dust cover

What would OPP monolayer packages be used for?

Overwraps and inside boxes

Typical Multilayer Structure communication

48 PET/adh/35 foil/adh/3 mil LLDPE or film/adh/foil/adh/film

What are positives and negatives of flexible regarding sustainability?

The light weight is desirable but the multilayers cause difficulty with recycling

Typical Printing Substrate layers

Paper, OPP, PET, or direct print on monolayers

What are some printing challenges in flexible?

Surface quality needs to be treated and dimensional stability

What are the two main printing processes?

Flexography and gravure

Barrier Materials used

Metallized films, glass coated films, PA or Nylon, oriented films, coated films, and foils

What is the relationship between performance and difficulty of packaging?

Directly correlated

What are some common sealant layers?

LLDPE, LDPE, and CPP

What is nice about LLDPE as a sealant?

There is a whole range of modified sealants for sealing through contaminants to peel able seals

What is nice about LDPE as a sealant?

There is no serious damage such as heat or chemicals involved

What is nice about C(cast)PP as a sealant?

It can be used in higher temperature applications that require polypropylene

What are shrink materials available for labels and sleeves?

PVC, PET, OPS, and PLA

What are available fitments and how are they made?

Polypropylene or polyethylene that are made by injection molding

How are zippers made?

Extrusion molded that can be pre-applied to a pre-made pouch or as the pouch is formed and fieled

What are some purposes of fitments?

Dispensing, reclosing, and aeration

What are the two form and fill methods?

VFFS and HFFS

What are the two types of HFFS methods?

Satchet and Flow

What are some types of pre made pouches?

Standing up with a seperate gusset, standing up with a folded bottom, box pouch, and a 4 side seal flat

What does package validation's rigor depend on?

The product

When is package validation very demanding?

Food and Drugs

What is package validation directly related to?

Safety

What does one of the ASTM document divides the validation process into?

3 groups of tests: Safety, Barrier, durability

What does safety validation consist of?

extractables, toxicity, retained solvents, and heavy metals

What does barrier validation consist of?

Porosity, microbial barrier, gas transfers, and light transmission

What does durability transimission consist of?

Flexural, bond strength, tensile, puncture, tear, and thickness

Tie Layer

adhesive layer

Most important processing parameters

melt temperature and processing time

EVA and PVDC

temperature sensitive and degrade

Coextrusions

Adding layers of films during extrusion process.

Layers are added for performance enhancement

Each layer maintains its identity

Wet Bonding

liquid adhesive applied to surface, immediately combined with second material, adhesive absorbs into surface of joining material, dried

(one of the substrates has to be paper)

Dry bonding

liquid adhesive applied to surface of material, passes through dryer to evaporate the carrier solvent, second ply applied using heated pressure nips

extrusion coating/laminating

thermoplastic material is melted and metered using an extruder and applied to the surface of material as it moves beneath the slit die, high temperature used for good adhesion

Coating Advantages

simple

less costly than lamination

thinner gauge

uses less materials

Coating Disadvantages

may not provide for all needs

Light viscosity

gravure, rod, knife or air

Medium Viscosity

Calendar coating, Kiss roll, nip, or reverse roll and Brush coater

Heavier Viscosity

extrusion and curtain coating

surface coatings

provide scuff resistance, gloss, and slip

seal coatings

hot and cold

wax coatings

excellent moisture barrier, resists grease and oil

polymer coatings

PE: heat sealing, flexibilty

PVDC: barrier properties (cellophane and PP)

PET: heat resistance (glass and metal)

Metallized or silica

barrier and crisping for microwave applications

Water Soluble

Used to carry additives and flavorings

(apples & foods)

Laminations

Combinations of 2 or more layers of materials using adhesive coating or thermal bonding

Possible materials: Polymeric films, paper, paperboard, and foil

Types of adhesion

Mechanical, Chemical, or diffusion

Corona Discharge

Ions in the discharge react with the film surface to produce polar groups on the film surface

oxidizes or roughs the surface

creates ozone

flame treatment

heats up and breaks long molecules of polyolefins into smaller ones

burns dust and other contaminates

doesn’t produce ozone

used on rigid containers

Adhesive failure

failure between the compounds ability to anchor to the surface of the substrate

cohesive failure

refers to the internal strength of the adhesive matrix