2. PET - PreformManufacturing & Blowing

PET BOTTLE QUALITY TOOL

Preform Manufacturing PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 1

Preform Manufacturing Packaging Quality Tool

Guiding Principles Process

Raw Materials

Preform/PET Bottle Manufacturing

Beverage Plant

Understand Raw Materials

Capability to manufacture PET bottles that meet PBI specifications

Maintain Quality of the Package after Receipt at the Beverage Plant

1) Starting materials for PET are Paraxylene & Ethylene 2) Starting materials form two intermediates (Ethylene Glycol & Terephthalic Acid) which react to form a monomer 3) Monomer is polycondensed to form a long polymer called Polyethylene Terephthalate (PET)

Concerns

1) Resin morphology - Degree of Crystallinity 2) Hydrolytic Degradation: - Drying of PET - Moisture Content 3) Intrinsic Viscosity(IV): - IV reduction

1) Resin Storage 2) PET Resin Drying 3) Injection molding of preforms 4) Preform in plant testing 5) Preform storage & distribution 6) Preform/PET bottle receipt and inspection 7) Preform storage 8) Preform Pre-heating 9) PET Bottle Blowing 10) PET Bottle Storage

1) Resin to be dried to < 50ppm 2) Thermal degradation (heat abuse) will lead to: a) Reduction in I.V. & b) Acetaldehyde (AA) generation 3) Maximum drop of 0.02 dl/gr. allowed 4) Preforms must be purchased from PBI qualified suppliers 5) Preforms should be conditioned over night prior to blowing 6) PET bottles stored in a dry environment

PQT: PET Preform Manufacturing

1) PET Bottle receipt, inspection and storage

Quality Assurance

Use Only PET bottles that Meet PBI Specifications PET bottle specifications

Supplier Approval

2) PET bottle rinsing/washing 3) Bottle filling 4) Filled PET bottle storage

PBI PET bottle Parameter

1) Receiving and inspection COC/COA ; minimum incoming inspection

1) PET bottles outside specifications 2) Stress-cracking

2) Base bursting 3) CO2 loss

FINAL: SEPTEMBER 2002

Bottle Appearance Dimensions Bottle Height Major Diameters Bottle Weight Fill Height Capacity Perpendicularity Wall Thickness Material Distribution Internal Pressure

Page 2

Preform Manufacturing Guiding Principle

(2) Understand the supplier’s capability to consistently supply PET bottles that meet PBI specifications

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 3

Preform Manufacturing Agenda

• Preform Manufacturing – Overview – Unit operations – Acetaldehyde (AA) – Preform in-plant testing

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 4

Preform Manufacturing Typical Description of a Preform Locking Ring Neck Finish Neck Support Ring

Body

• Neck Finish does not change after injection molding process • Preform body is stretched in blowing process • Gate area does not change after injection molding process

Gate PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 5

Preform Manufacturing Bottle Finish Dimension Letters

Band

The standard neck finishes are: - BPF: British Plastic Federation - PCO: Plastic Closure Only www.threadspecs.com PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 6

Preform Manufacturing How are Preforms Made and Their Critical Parameters • I.V.: 0.80-0.84+/-0.02 dl/gr. • Acetaldehyde:

I.V. reduction between resin and preform (< 0.02dl/gr. Max.)

< 1 ppm

PET Resin

PET PETResin Resin Receipt Receipt && Storage Storage

PET PETResin Resin Drying Drying

Moisture: 14ppm

FINAL: SEPTEMBER 2002

Page 7

Preform Manufacturing Receipt and Storage of PET Resin Dried at -40C dewpoint and 180C (356F) PET Resin PET Resin

PET Resin PET Resin Receipt Receipt & Storage & Storage

PET Resin PET Resin Drying Drying

Injection Molding Injection Molding of Preforms of Preforms

Preform Preform Handling & Handling & Storage Storage

Preform Preform

Process: • PET resins are shipped in corrugated boxes, bulk tank trucks and bulk rail cars to the preform manufacturing facility • Resins are stored in silo’s with a capacity of 75 tonnes (approx.) • Silo’s are typically made of aluminum and/or stainless steel PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 8

Preform Manufacturing Receipt and Storage of PET Resin Dried at -40C dewpoint and 180C (356F) PET Resin PET Resin

PET Resin PET Resin Receipt Receipt & Storage & Storage

PET Resin PET Resin Drying Drying

Injection Molding Injection Molding of Preforms of Preforms

Preform Preform

Preform Preform Handling & Handling & Storage Storage

Concern: • Bulk tankers should be cleaned prior to loading and transportation • Good manufacturing practices should be followed in the transfer of resin to the silos. Avoid soil contamination, i.e. stones being pick up in the transfer process • Stainless steel flexing should be used in the resin transfer process. Avoid using rubber hosing as it wears quickly PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 9

Preform Manufacturing How is Drying of PET Resin Accomplished? Process: • Drying involves placing the PET polymer in a drier of between 0.5 and 4 metric tons capacity and blowing hot dry air through it • It will typically take between 5 to 7 hours in the drier for the PET polymer to obtain the correct moisture level (< 50ppm) for processing • Carefully controlled drying is an essential requirement in order to remove the moisture from the granules • Faulty drying cannot be reversed later on in the conversion process (PET resin to Preform) • The most common type of drying method used is the Heated Air with Desiccant Dehumidifying process PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 10

Preform Manufacturing How is Drying of PET Resin Accomplished? Dried at -40C dewpoint and 180C (356F) PET Resin PET Resin

PET Resin PET Resin Receipt Receipt & Storage & Storage

PET Resin PET Resin Drying Drying

Injection Molding Injection Molding of Preforms of Preforms

Preform Preform

Preform Preform Handling & Handling & Storage Storage

Concern: • The presence of a high moisture level in the resin will result in: - Reduction of the Intrinsic Viscosity (I.V.) of the PET material which will result in poor material distribution within the PET bottle (accelerated CO2 loss with the finished beverage). PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 11

Preform Manufacturing Injection Molding of Preforms Dried at -40C dewpoint and 180C (356F) PET Resin PET Resin

PET Resin PET Resin Receipt Receipt & Storage & Storage

PET Resin PET Resin Drying Drying

Injection Molding Injection Molding of Preforms of Preforms

Preform Preform

Preform Preform Handling & Handling & Storage Storage

Process: • PET resin is melted, compressed in an extruder and then injected into water cooled cavities where it quickly solidifies to form a preform • Preforms are then stored and later transported to a PET blowing operation for stretch-blowing into PET bottles PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 12

Preform Manufacturing Injection Molding of Preforms PET Resin

Preform

Core Pin

Cavity Sprue

Gate section

PQT: PET Preform Manufacturing

Extruder

Screw Barrel (~ 290C/554F to 320C/608F)

FINAL: SEPTEMBER 2002

Page 13

Preform Manufacturing Injection Molding of Preforms PET Resin

Preform

Core Pin

Cavity

Sprue

Screw

Gate section

Barrel (~ 290C/554F to 320C/608F)

Concern: • Minimize resin degradation(thermal) which will result in: a) I.V. reduction (0.02dl/gr. Max. allowed), and b) high acetaldehyde • Preform clarity issues due to poor cooling of the preforms PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 14

Preform Manufacturing Agenda

• Preform Manufacturing – Overview – Unit operations – Acetaldehyde (AA) – Preform in-plant testing

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 15

Preform Manufacturing What is Acetaldehyde (CH3CHO)? Acetaldehyde (AA): • In its pure state Acetaldehyde (AA) has a sharp fruity sweet apple taint • The rate of formation of AA is dependent on the PET resin formula and drying efficiency • AA is only formed in significant quantities during the preform injection molding process • At room temperature (20°C/68°F), Acetaldehyde is a colorless vapor which is soluble in water • Acetaldehyde (AA) is a product of thermochemical (high temperature abuse) degradation PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 16

Preform Manufacturing What is Acetaldehyde (CH3CHO)? • The presence of a high concentration of AA would indicate; – Poor processing conditions which could also result in a large drop in the resin I.V. value (when resin is converted to a preform)

• In the injection molding equipment certain cavities will consistently produce high AA values in preforms • These cavities are called High (Hot) or critical cavities • In performing AA analysis, one of these critical cavities should be sampled once a week per mold to determine AA concentration Preform AA specification: Average AA < 10ppm, no one cavity > 14ppm PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 17

Preform Manufacturing Concerns From Preform Production Haze

Defect type: Hazy preforms Description: Appears with varying amounts of crystallinity in the preform sidewall Resin not dried Cause: properly prior to processing Concern: Stress cracking of the filled PET bottle

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 18

Preform Manufacturing Concerns From Preform Production

Short Shots

Defect type: Short Shots Description: Neck finish not completed

PQT: PET Preform Manufacturing

Cause:

In-sufficient polymer was packed during the injection fill time

Concern:

Poor bottle/closure seal - High CO2 loss

FINAL: SEPTEMBER 2002

Page 19

Preform Manufacturing Agenda

• Preform Manufacturing – Overview – Unit operations – Acetaldehyde (AA) – Preform in-plant testing

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 20

Preform Manufacturing Typical In-Plant Testing Regime at the Preform Supplier PET Resin Receipt & Storage

PET Resin

PET Resin Drying

Injection Molding of Preforms

Preform

Preform Handling & Storage

Test:

Frequency:

Equipment:

Preform weight

A full round/day/mold

Weighing Balance

Preform wall thickness

5 Preforms/day/mold

Magna-Mike, Panametrics

Finish dimension

During mold change over

Callipers, Profile projector

Visual inspection

A full round/shift /mold

Magnifying Glass

I.V.

Critical cavity/week/mold as a minimum

As per ASTM D-4603

Acetaldehyde (AA)

Critical cavity/week/mold as a minimum

Gas Chromatograph

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 21

Preform Manufacturing Preform Handling and Storage

• Normally packed in polyethylene plastic bags which are closed to the surrounding environment • Polyethylene liner is used to prevent dust and dirt contamination • Preforms should not be stored in direct sunlight • Stored in a covered/closed warehouse with ideal temperatures of between 5°C/41°F to 35°C/ 95°F at Relative Humidity < 60% • 12 months maximum for storage of preforms is recommended (from date of preform manufacture) PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 22

Preform Manufacturing Preform Handling and Storage

• Information that should accompany the shipment: a) Name of Supplier/City/Country b) Lot Identification: • • • • •

Lot code Neck finish type Shift Production date Color

• • • • •

Resin type Preform quantity/boxes Preform weight Shipment date Injection machine/line

c) Certificate of Compliance/Analysis (COC\COA)

PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 23

Preform Manufacturing What are the Key Take-Aways From This Module? • Under controlled drying and molding conditions the I.V. loss for dried PET resin conversion to a preform shall be less than 0.02dl/gr. • Preforms can be stored for up to 12 months in a closed/covered environment warehouse with ideal temperatures of between 5°C/41°F to 35°C/95°F at Relative Humidity < 60% • The rate of formation of AA is dependent on the PET resin formula and is formed only in significant quantities during the preform injection molding process • Preform Acetaldehyde specification: Average AA < 10ppm, no one cavity > 14ppm PQT: PET Preform Manufacturing

FINAL: SEPTEMBER 2002

Page 24

PET BOTTLE QUALITY TOOL

PET Bottle Blowing PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 1

PET Bottle Blowing Packaging Quality Tool

Guiding Principles Process

Raw Materials

Preform/PET Bottle Manufacturing

Beverage Plant

Understand Raw Materials

Capability to manufacture PET bottles that meet PBI specifications

Maintain Quality of the Package after Receipt at the Beverage Plant

1) Starting materials for PET are Paraxylene & Ethylene 2) Starting materials form two intermediates (Ethylene Glycol & Terephthalic Acid) which react to form a monomer 3) Monomer is polycondensed to form a long polymer called Polyethylene Terephthalate (PET)

Concerns

1) Resin morphology - Degree of Crystallinity 2) Hydrolytic Degradation: - Drying of PET - Moisture Content 3) Intrinsic Viscosity(IV): - IV reduction

1) Resin Storage 2) PET Resin Drying 3) Injection molding of preforms 4) Preform in plant testing 5) Preform storage & distribution 6) Preform/PET bottle receipt and inspection 7) Preform storage 8) Preform Pre-heating 9) PET Bottle Blowing 10) PET Bottle Storage

1) Resin to be dried to < 50ppm 2) Thermal degradation (heat abuse) will lead to: a) Reduction in I.V. & b) Acetaldehyde (AA) generation 3) Maximum drop of 0.02 dl/gr. allowed 4) Preforms must be purchased from PBI qualified suppliers 5) Preforms should be conditioned over night prior to blowing 6) PET bottles stored in a dry environment

PQT: PET Bottle Blowing Manufacturing

1) PET Bottle receipt, inspection and storage

Quality Assurance

Use Only PET bottles that Meet PBI Specifications PET bottle specifications

Supplier Approval

2) PET bottle rinsing/washing 3) Bottle filling 4) Filled PET bottle storage

PBI PET bottle Parameter

1) Receiving and inspection COC/COA ; minimum incoming inspection

1) PET bottles outside specifications 2) Stress-cracking

2) Base bursting 3) CO2 loss

FINAL: SEPTEMBER 2002

Bottle Appearance Dimensions Bottle Height Major Diameters Bottle Weight Fill Height Capacity Perpendicularity Wall Thickness Material Distribution Internal Pressure

Page 2

PET Bottle Blowing Guiding Principle

(2) Understand the suppliers capability to consistently supply PET bottles that meet PBI specifications

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 3

PET Bottle Blowing Agenda

• Best Practice recommendations for incoming preforms • Operational Practices – Preform receipt and inspection – Preform storage – PET bottle stretch-blowmolding – PET bottle storage

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 4

PET Bottle Blowing Best Practice Recommendations for Preforms

• Preforms are purchased only from approved suppliers • Bottle blower is responsible for approving the preform supplier. • Preforms must meet PBI Preform specifications • COC/COA requirements are met on new preforms either: – By supplier providing COC/COA with every lot, or – By COA testing being performed at the PET blowing facility for each lot of preforms delivered PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 5

PET Bottle Blowing PET Bottle Process Overview

PREFORM RECEIVING/ INSPECTION

PREFORM STORAGE

PET BOTTLE BLOWING

EMPTY PET STORAGE

BEVERAGE PLANT

Process: • Sampling • COC/COA • Incoming Tests

Concerns: • Acetaldehyde • Intrinsic Viscosity • Visual Defects

• Preform storage

• Preform conditioning • Preheating oven • Stretch-blowing

• Storage time/temp • Mixing preforms with • Relative humidity different I.V.’s • FIFO • Stretch rod and preblow timing

PQT: PET Bottle Blowing Manufacturing

• Empty PET bottle storage

•Temperature • Humidity • Odor • FIFO

FINAL: SEPTEMBER 2002

Page 6

PET Bottle Blowing Receiving/Inspection

• Obtain bill of lading • Verify truck cleanliness • Verify the certificate of compliance/analysis • Check preform pallet labels for correct details

PREFORMS PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 7

PET Bottle Blowing COC & COA Requirements

• COC (Certificate of Compliance) – Written documentation showing contract terms – Preform specification requirements (include preform drawing reference number & resin type)

• COA (Certificate of Analysis) – Data for critical parameters: • • • • •

Appearance Dimensions (include neck finish) Intrinsic Viscosity of a) PET resin and b) preform Acetaldehyde Weight

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 8

PET Bottle Blowing Certificate of Compliance /Analysis

Certificate of Compliance & Analysis

Certificate of Compliance/Analysis for Preforms Supplier/Distributor Bill of Lading No. Shipped To (PET Blowing Plant) Date Delivered: Batch No.: Resin Type: Preform Drawing No.:

___________________ ___________________ ___________________ ___________________ ___________________ ___________________ ___________________

This is to certify that the preforms contained in this shipment meets and conforms to all requirements called for in PepsiCo Beverage International’s specifications dated_____. Furthermore, the preforms in the specified delivery have been analyzed and the data recorded for the specific standards shown below.

• Provided by preform supplier • Does not replace inspection criteria for the PET bottle facility • Analyses must be from that preform lot PQT: PET Bottle Blowing Manufacturing

Test Items

Specification

Appearance

Free of visual defect

Test Result

Weight

< 30 grs: +/- 0.3 grs > 30 grs: +/-0.4 grs

Neck Finish Dimension a) Resin Intrinsic Viscosity b) Preform Intrinsic Viscosity Acetaldehyde

As shown in PBI approved drawing 0.80-0.84 +/- 0.02 dl/gr Maximum IV drop of 0.02 dl/gr from the initial resin I (as per ASTM#D4603) Avg. < 10.0 ppm with no individual cavity in excess of 14.

* Only official PepsiCo Beverages International test methods must be used.

Certified by: on (Signature)

(Date)

______________________________ of _______________________________

FINAL: SEPTEMBER 2002

Page 9

PET Bottle Blowing Incoming Preform Receiving Process

NO COC/COA

COC/COA TESTING

REQUIRED

• Appearance

• Appearance

• Weight

• Weight

3 SAMPLES/LOT

• Dimensions • Intrinsic Viscosity of Preform • Acetaldehyde (AA) 10 SAMPLES/LOT

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 10

PET Bottle Blowing Recommended Sampling Plan with No COC/COA?

• Sample randomly 10 preforms per truck or trailer delivery. Samples should be taken from the front, end, and middle of truck. • Evaluate these samples for: 1. Appearance 2. Dimensions (include neck finish) 3. Weight 4. Intrinsic viscosity 5. Acetaldehyde (AA)

If results are out of specification, then reject this lot of incoming preforms

A Lot is defined as a truckload (trailer) of preforms PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 11

PET Bottle Blowing Process Overview

PREFORM RECEIVING/ INSPECTION

PREFORM STORAGE

PET BOTTLE BLOWING

EMPTY PET STORAGE

BEVERAGE PLANT

Process: • Sampling • COC/COA • Incoming Tests

Concerns: • Acetaldehyde • Intrinsic Viscosity • Visual Defects

• Preform storage

• Preform conditioning • Preheating oven • Stretch-blowing

• Empty PET bottle storage

• Storage time/temp • Relative humidity

• Mixing preforms with different I.V.’s • Stretch rod and preblow timing

• Temperature • Humidity • Odor • FIFO

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 12

PET Bottle Blowing Storage of Preforms at the Beverage Plant • A “First In, First Out” principle should be applied in the case of preform inventory • Preforms age during storage – 12 months maximum • The degree of aging is dependent upon storage temperature and relative humidity. Acceptable storage conditions are: – Storage temperature

5°C/41°F to 35°C/95°F

– Relative Humidity

< 60%

• As the age of the preform changes so too might the preheating oven set up conditions prior to PET bottle blowing • Transit packaging containing preforms should not be stacked too high as preform necks can be damaged (oval) PQT: PET Bottle Blowing Manufacturing

UPDATED: MARCH 2003 FINAL: SEPTEMBER 2002

Page 13

PET Bottle Blowing Process Overview

PREFORM RECEIVING/ INSPECTION

PREFORM STORAGE

PET BOTTLE BLOWING

EMPTY PET STORAGE

BEVERAGE PLANT

Process: • Sampling • COC/COA • Incoming Tests

Concerns: • Acetaldehyde • Intrinsic Viscosity • Visual Defects

• Preform storage

• Preform conditioning • Preheating oven • Stretchblowing

• Storage time/temp • Mixing preforms with • Relative humidity different I.V.’s • Stretch rod and preblow timing

PQT: PET Bottle Blowing Manufacturing

• Empty PET bottle storage

• Temperature • Humidity • Odor pickup

FINAL: SEPTEMBER 2002

Page 14

PET Bottle Blowing PET Stretch-Blowing Process Preform is heated

Preform is blown into a PET bottle

(~ 105C/221F)

(~ 65C/149F) Preform

Stretch Rod

Mold

PET bottle blowing occurs in four steps: 1) Preform conditioning, 2) Preform heating, 3) Mechanical axial stretching & 4) Radial stretching using compressed air PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 15

PET Bottle Blowing Step 1: Preform Conditioning Process: • Preforms are stored in a warm dry area (Blowing hall preferably) for a minimum of 24 hours prior to pre-heating and blowing. • This conditioning allows for the preforms to be of a more uniform temperature profile when presented to the pre-heating oven Concern: • Mixing preforms from different lots, different storage conditions (i.e., temperature), different resins, and preform age can result in the following issues occurring with the blown PET bottle; a) Crystallinity (Preforms too hot or cold) • PET bottle opaque in color b) Pearlescence (Preforms too cold) • Hazy effect throughout bottle c) Poor material distribution • Cold or unevenly heated preforms • Difficult to adjust the blowing machine PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 16

PET Bottle Blowing Step 2: Preform Heating

Process: Infra Red lamps

• Pre-heating oven consists of 8 -10 heating zones (infra-red lamps). Heat intensity in heating zones is adjustable to facilitate material distribution • Preform neck is protected from heat by cooling shield

Concern:

Neck shields

• Poor preform heating results in: 1. Poor material distribution in PET bottle 2. Poor wall thickness in PET bottle 3. Pearlescence on PET bottle sidewall

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 17

PET Bottle Blowing Step 3: Mechanical Axial Stretching Process: • Heated Preforms (110°C/230°F approx.) are transferred to the blow-molding equipment. • Preforms are placed between two blow mold section halves. Mold temperatures of 65°-95°C (149°-203°F) are typical. • Mold sections are closed and clamped.

Preform (Heated)

Concern:

Mold Mold Closes Around Preform

• If mold temperatures are too high then excessive shrinkage will occur, resulting in low fill height capacity issues in the PET bottle. • Any preforms that drop out of the transfer unit (between heating oven and stretch-blowing equipment) must be scrapped.

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 18

PET Bottle Blowing Step 3: Mechanical Axial Stretching Air starts to inflate preform

Process:

• Stretch rod is introduced via the preform neck which longitudinally stretches the preform to the bottom of the mold • Axial molecular orientation takes place during this Stretch rod stretching process (Pushes • Air is then introduced into the bottle to distribute the preform material radially (around circumference)

downwards)

Concern: • Rate that the preform is stretched is critical to the level of orientation in the PET bottle • Timing of the stretch rod and air blow, are critical in forming a good PET bottle (moving material to the right places)

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 19

PET Bottle Blowing Step 4: Radial Stretching Using Compressed Air Process: Air

Air

Air drives preform sidewalls outwards to the mold surface

Occurs in 2 Stages: 1) Pre-Blow and 2) Main Blow: • Pre-Blow – Typically 9 bar pressure – Radial orientation of molecules takes place – Timing of pre-blow determines amount of material in base • Main Blow – Typically 40 Bar Pressure – Follows Pre-Blow – Gives the final definition to the bottle shape

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 20

PET Bottle Blowing Step 4: Radial Stretching - Main Concerns

Air

Air

Air drives preform sidewalls outwards to the mold surface

Concerns: • In-correct timing between the stretch rod initial movement and the pre-blow stage will result in poor material distribution within the PET bottle. (Material begins to move early in the blowing process to the PET bottle shoulder and base areas - Results in accelerated CO2 loss in filled PET bottles. • Inadequate venting of the air from the mold can result in flat sidewalls at the parting lines. Defect known as Panelling which leads to foaming issues at the filler

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 21

PET Bottle Blowing What Happens to the Preform During PET Bottle Blowing?

Stretch Blow molding & Biaxial Orientation: • Preform is biaxially stretched during blow molding (circumferentially & axially) • This biaxial orientation impacts certain physical properties, i.e., Gas permeation through the sidewall is decreased • The degree of biaxial orientation is influenced by how fast the bottle is stretched (Axial direction) and blown circumferentially PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 22

PET Bottle Blowing Typical Types of Defects Found in Stretch-Blowing Defect Type:

Visual Aid:

Strangled Neck: Too much material in top shoulder area of PET bottle Underblown Feet: Base area of the PET bottle is not fully formed

PQT: PET Bottle Blowing Manufacturing

Cause: • Pre-blow too late • Preforms over or underheated

• Pre-blow too fast • Insufficient blow pressure

Filled PET issue

Remedy:

• Accelerated CO2 loss, and PET filling issues (foaming).

• Correct pre-blow timing

• PET bottle stability issues, accelerated CO2 loss and potential stress-cracking problems

• Correct pre-blow timing

• Correct heat shields (reflectors)

• Adjust air pressure higher

• Less fill height capacity FINAL: SEPTEMBER 2002

Page 23

PET Bottle Blowing Typical Types of Defects Found in Stretch-Blowing Defect Type: Crystallinity: Material appears as opaque or milky white in appearance

Off Center Gate: Gate section is not centered correctly

Visual Aid:

Cause:

Filled PET issue:

• Preforms too hot • Potential stressCrystallinity (Haze on outside) cracking issues, and accelerated • In-adequate CO2 loss mold cooling • Pre-blow pressure high

Off Center Gate

• Pre-blow too fast before stretch rod centers on gate • Preform slants

PQT: PET Bottle Blowing Manufacturing

Remedy: • Lower heating power • Check mold cooling water • Adjust preblow pressure

• Poor material distribution, accelerated CO2 loss and potential stresscracking issues

FINAL: SEPTEMBER 2002

• Correct preblow timing • Lower blow air pressure • Check mold & thread alignment Page 24

PET Bottle Manufacture - Stretch-blowing Typical PET Bottle In-Plant Testing Regime Test:

Frequency:

Equipment:

Neck Finish Dims.

One sample/mold/shift (8 hours)

Callipers, Micrometer

Stress Cracking

One sample /mold/week

0.2% NAOH, Stop Watch

Top Load

One sample/mold/shift (8 hours)

Top Loader (e.g. Instron)

Burst Test

One sample/mold/4 hours

AGR Model 073

Fill Height Capacity

One sample/mold/shift (8 hours)

Weighing Balance, Water Density Tables, Thermometer

Sectional Weights

One sample/mold/2 hours

Weighing Balance, Cutting Tool

Visual Inspection

One sample/mold/shift (8 hours)

Magnifying Glass

Drop Impact Test

One sample/mold/shift (8 hours)

Concrete slab, Temperature chambers

Dimensions (Height, Diameters)

One sample/mold/shift (8 hours)

Callipers, Micrometer, Height Gauge

PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 25

PET Bottle Blowing One Stage vs. Two Stage Process

Two Stage

PQT: PET Bottle Blowing Manufacturing

One Stage

FINAL: SEPTEMBER 2002

Page 26

PET Bottle Blowing One Stage vs. Two Stage Process Item:

Two Stage:

One Stage:

¾ Level Of Bi-orientation

Higher (Lower Preform Temp)

Lower

¾ Material Distribution

Optimum (Preform Design)

Some issues under neck stretching

¾ AA Level

Low

High

¾ Moisture Pick Up

During Preform Storage

No moisture pick-up

¾ Scrap Rate

Low (< 1%)

PQT: PET Bottle Blowing Manufacturing

High (2 - 4%)

UPDATED: MARCH 2003 FINAL: SEPTEMBER 2002

Page 27

PET Bottle Blowing Cost Breakdown of a PET Bottle 3% 2% 15%

PET Resin Other Labour Scrap

80%

Resin prices are a key cost when evaluating economics PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

Page 28

PET Bottle Blowing Process Overview

PREFORM RECEIVING/ INSPECTION

PREFORM STORAGE

PET BOTTLE BLOWING

EMPTY PET STORAGE

BEVERAGE PLANT

Process: • Sampling • COC/COA • Incoming Tests

Concerns: • Acetaldehyde • Intrinsic Viscosity • Visual Defects

• Preform storage

• Preform conditioning • Preheating oven • Stretchblowing

• Storage time/temp • Mixing preforms with • Relative humidity different I.V.’s • Stretch rod and preblow timing

PQT: PET Bottle Blowing Manufacturing

• Empty PET bottle storage

• Temperature • Humidity • Odor pickup

FINAL: SEPTEMBER 2002

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PET Bottle Blowing Empty PET Bottle Storage • First In, First Out principle should be applied in the case of empty PET bottle inventory • PET bottles should be stored in a dry environment. Ideal conditions are – Storage temperature: 5°C/41°F to 35°C/95°F – Relative Humidity: < 60% • Keep PET bottles away from substances that emit strong odors and direct sunlight (PET transportation and warehousing) – Lot Identification: • Production date • Lot code • Neck finish type • Color • Resin type • Date • PET Bottle Weight • Shift PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

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PET Bottle Blowing Empty PET Bottle Storage

• PET bottles are normally packed into cardboard trays which are placed on wooden pallets (up to 8 layers in height) • These pallets of empty PET bottles are normally stretch-wrapped and stored in the warehouse at no more than 4 pallets high. • Silo storage is used as an alternative with some beverage plants. • While no specific age limit exists, bottles more than 6 months old may be subject to secondary shrinkage, rendering them unsuitable for use (Fill height issues) PQT: PET Bottle Blowing Manufacturing

FINAL: SEPTEMBER 2002

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PET Bottle Blowing Key Take-Aways • Preforms are purchased only from approved suppliers • COC/COA reduces the need on the PET blowing facility to perform incoming testing on the preforms • Preforms should be stored for 24 hours in the same room prior to PET bottle blowing • PET bottles should be stored in a dry environment Acceptable conditions are: – Storage temperature

5°C/41°F to 35°C/95°F

– Relative Humidity

< 60%

PQT: PET Bottle Blowing Manufacturing

UPDATED: MARCH 2003 FINAL: SEPTEMBER 2002

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