Extrusion Coating Substrates. Kelly R. Frey Chevron Phillips Chemical Company LP. TAPPI Extrusion Coating Course August Charleston, SC

Transcription

1 Extrusion Coating Substrates Kelly R. Frey Chevron Phillips Chemical Company LP TAPPI Extrusion Coating Course August Charleston, SC Learning Objectives Identify the components of a typical extrusion coated or laminated structure. Understand the properties and requirements of each component in a structure. Understand the various types of substrates available for use in extrusion coating and laminating. Learn how to put various substrates together to build a structure. 1

2 Substrates The building blocks used to produce a finished i structure. t Materials are selected based on Function & Design Requirements of the package» What will it hold?» How will it be converted, filled and distributed?» How will it need to look?» How will it be used?» How much protection is required? (Moisture, Gas, Chemical, Flavors, Aromas, Light, Dirt and Dust)» How much will product cost? E/C & Lamination Lines E/C & Lamination lines are designed to run three types of substrates: Thin films at low tension levels (5-100lbs of tension) e.g. chip bags Paper, film and foil combinations (20-200lbs of tension) e.g. stand-up pouch High tension paperboard applications ( lbs of tension) e.g. hot & cold drink cups..these lines combine resins or adhesives with substrates to produce.. 2

3 Typical Structure Outside / (Bulk, Barrier, and/or Tie) / Inside Outside Layer (Primary Substrate) Considerations for the outside layer: Printable Print may need to be protected Maybe sealable (e.g. lap seal) Maybe not sealable (e.g. fin seal) Low COF for converting Hi h t h i t f High scratch resistance for appearance May need to receive a coating (silicone release liners) Adhesion to the next layer 3

4 Tie Layers Considerations for the tie layers: Composition of layers being tied together Adhesion method (adhesive, extrusion, primers) Amount of bond required Failure required (cohesive or adhesive failure) Bond strength over time (chemical attack, bond change due to materials, etc). Bulk Layers Considerations for the bulk layers: Cost Thickness/Modulus Adhesion and compatibility with other layers. How will the bulk layer affect appearance, machineability, converting, and use of the structure. How will the bulk layer affect appearance, machineability, converting, and use of the structure. Strength properties (tear, puncture, etc) 4

5 Barrier Layers Considerations for the barrier layer: Type of barrier (Moisture, Gas, Solvent, Aroma, Light, Microbial) How much barrier is required? Is the barrier also providing grease or chemical resistance/barrier? Does the barrier need to be clear or can it be opaque? Abuse resistance (cracking or pinholes). Does the product require a scavenger in addition to a barrier? Don t consider only the permeation through the face of the structure but permeation through the seal of the package, as well. Inside Layer (Aux. Substrate) Considerations for the inside layer Typically the sealant layer» What will it need to seal to? (lap seal, fin seal)» Seal temperature & seal strength.» Seal through contaminants (powders, grease, etc)» Peelable sealant Low COF for converting Food Contact (flavor scalping, taste and odor) Appearance 5

6 Putting it all together These considerations and requirements will dictate the types of materials used in the structure with the overall goal to: Functionality & Performance Cost Extrusion Lamination / Coating Process 6

7 Substrates Paper Paper (Less than 7mils in thickness) Measured in lbs/ream - Low Cost - Some bulk and deadfold - Strength (X,Y & Z Direction) - Opaque - Natural and Bleached and Clay Coated -Easy to obtain adhesion (mechanical and chemical) -Easy and forgiving to run and hide gauge bands. - Poor Barrier & Chemical Resistance - Non-Sealable - Properties change depending upon moisture content - Rough surface can produce pinholes. 7

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9 Paperboard Paperboard (greater than 7mils) Measured by thickness points. - Strength (X,Y & Z Direction) - Opaque - Natural and Bleached and Clay Coated -Easy to obtain adhesion (mechanical and chemical) -Can be easy to run and hide gauge bands. -Easy and forgiving to run and hide gauge bands. - Poor Barrier & Chemical Resistance - Non-Sealable - Properties change depending upon moisture content - Rough surface can produce pinholes. Cellophane Cellophane - Excellent Optics - Good Stiffness - Good Printability - Excellent twist retention - Good Machineability - Poor Barrier - Poor Tear Strength - Non-Sealable - Can turn color over time. 9

10 OPP OPP - Excellent Optics - Good Stiffness - Greaseproof - Heat Sealable Grades - Opaque (Cavitated OPP) -Metallized or PVdC OPP Good Barrier -Good Machineability -Flex resistance vs. Cellophane (2700+ on Gelbo) -Cost - Tear Strength - Treatment or primer required for adhesion - Metallized surface can scratch easily OPET OPET - Excellent Optics - Excellent Stiffness (> Than OPP) - Good Strength - Good Oxygen Barrier - High Heat Resistance - Metallized or PVdC PET Good Moisture and Gas Barrier -Good Machineability - High Abrasion Resistance -Cost - Poor Tear Strength, once tear is initiated. Harder to initiate tear than OPP. - Poor Moisture Barrier Compared to OPP. - Treatment or primer required for adhesion. Can be harder to adhere to than OPP. -Metallized surface can scratch easily 10

11 Foil Foil - Ultimate Barrier (if pinhole free) - Optics for Decorative Structures -Cost - Very Weak - Non-Sealable - Hard to Print - Can be hard to get adhesion. - At gauges of less than 1mil pinholes can be present. Metallized Film Metallized Film (Cellophane, OPP, Nylon & PET) - Barrier - Many grades available, Cellophane, OPP, Nylon, PET, etc) - Heat sealable grades available. -Cost - If scratched then barrier is significantly reduce. - Does not offer the stiffness and deadfold of foil. 11

12 Nylon Film Nylon Film - Optics - Very high toughness, tensile, and abrasion resistance. - Good oxygen barrier. - High heat resistance (withstand steam steralization 140C and even hotter with dry heat). - Good odor barrier. - Biax improves strength, stiffness, and optics as well as barrier - Excellent grease resistance. -Cost - High water absorption which change mechanical properties (only temporarily). - Does not offer the stiffness and deadfold of foil. PE Films PE Films - Cost (Depending Upon Type) - Good Optics (Depending upon type) - Good Sealability - Moisture Barrier - Low Temperature Abuse Resistance - Good Toughness and Tear - Orientation in both directions for blown film. - Good optics for cast film. - Cost (Depending Upon Type) - Low Stiffness Compared to OPP and PET - Poor oxygen barrier. -Low Temperature Resistance. - Subject to environmental stress cracking. 12

13 Cast PP Films Cast PP Films -Cost - High Elongation at Break - MVTR better than LDPE but not quite as good as HDPE. - Chemical Resistance - Oil & Grease Resistance - Good Twist Retention - Poor Tear Strength - Poor Impact Strength at Low Temp (below 0C) -Low Temperature Resistance. - Subject to environmental stress cracking. Film Process Comparison Capital Cost Output Gauge Control Optical Properties Retrofit to Coex Additive Loading Film Strength Biax Orientation CAST FILM BLOWN FILM 13

14 Non-Wovens Non-Wovens (PET, PP, & Cellulose) - Cloth like appearance and feel - Breathable - High Bulk - High Strength - Easy to get adhesion (mechanical adhesion). - Specialty applications: -Filters, Wipes, Automotive, Building Materials, Hygiene, etc. - Low Barrier - Low Grease and Chemical Resistance - Pinholes MVTR 100 G-mil/100sq.in./day/atm

15 OTR Cc-mil/100sq.in./day/atm C Barrier Coatings Aluminum and Silicon Oxide Coatings Al 2 O 3 & SiO x are now being applied to PET and OPP to improve oxygen and moisture barrier similar to foil. Produces metal-free, retortable, microwavable, transparent, environmentally friendly, high barrier films. Barrier layer is only angstroms thick, making OPP and PET recyclable. SiO x can have an amber tint and Al 2 O 3 a grey tint. Care must be taken when flexing, not to crack coating. Development work on depositing these coatings at atmospheric conditions. Polyvinylidine Chloride (PVdC) Barrier Coating with good oxygen and moisture barrier. Barrier levels is dependent upon thickness, often multiple applications on one substrate. 15

16 Barrier Coatings Continued Polyvinyl Alcohol (PVOH) PVOH can be a film or a coating. As a coating it provides excellent oxygen barrier. Dependent upon thickness. Moisture sensitive and will dissolve when exposed to moisture. Tying It All Together EAA NA Ionomer ZN Ionomer Foil EVA LDPE HDPE OPP Nylon EVOH OPET EMAC EMAC OPET EVOH Nylon OPP HDPE LDPE EVA Foil ZN Ionomer NA Ionomer Good Adhesion Fair Adhesion Poor Adhesion EAA 16

17 Thank-you! 17