Susan E. M. Selke John D. Culter. Plastics Packaging. Properties, Processing, Applications, and Regulations. 3rd Edition

Transcription

1 Susan E. M. Selke John D. Culter Plastics Packaging Properties, Processing, Applications, and Regulations 3rd Edition

2

3 Selke, Culter Plastics Packaging

4

5 Susan E. M. Selke John D. Culter Plastics Packaging Properties, Processing, Applications, and Regulations 3rd Edition Hanser Publishers, Munich Hanser Publications, Cincinnati

6 The Authors: Susan E. M. Selke, Director, School of Packaging, Michigan State University, 448 Wilson Rd., Rm. 135, East Lansing, MI John D. Culter, President, Advanced Materials Engineering Inc., 1231 Silver Lakes Blvd., #132, Naples, FL Distributed in the Americas by: Hanser Publications 6915 Valley Avenue, Cincinnati, Ohio , USA Fax: (513) Phone: (513) Distributed in all other countries by: Carl Hanser Verlag Postfach , München, Germany Fax: +49 (89) The use of general descriptive names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. While the advice and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. The final determination of the suitability of any information for the use contemplated for a given application remains the sole responsibility of the user. Cataloging-in-Publication Data is on file with the Library of Congress All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying or by any information storage and retrieval system, without permission in writing from the publisher. Carl Hanser Verlag, Munich 2016 Editor: Cheryl Hamilton Production Management: Jörg Strohbach Coverconcept: Marc Müller-Bremer, München Coverdesign: Stephan Rönigk Printed and bound by Hubert & Co., Göttingen, Germany ISBN (US): ebook ISBN (US): ISBN (DE): ebook ISBN (DE):

7 Preface This book is intended to provide a basic understanding of plastic packaging materials. It covers the properties of common packaging plastics, and relates these properties to the chemical structure of the polymers. Common processing methods for transforming plastic resins into packages are covered. In this book we discuss the uses of plastics in packaging. Although this is not a course in chemistry nor in material science, we attempt to stress the relationship between chemical structure and packaging material properties. We expect the reader to have some knowledge of chemistry and physics. The major purpose of this book is to provide the students in the School of Packaging with reading material on plastics for packaging; however, we hope that it can also be useful to packaging professionals responsible for writing specifications, designing, fabricating, testing, and controlling the quality of plastic materials. We also hope to trigger the readers curiosity to pursue further studies in the exciting world of packaging materials. This third edition fixes some of the errors that, despite our best efforts, found their way into the previous editions. Unfortunately, we re sure that we have still not found them all! We have expanded and updated the discussion of biobased plastics such as PLA and PHA, plastics recycling, life cycle assessment, and a variety of other topics. We have deliberately included some information that goes well beyond what would normally be included in an introductory level packaging course, in order that it will be available for the more advanced student and for the practitioner. The Study Questions at the end of each chapter are intended to serve as review of the main concepts, and also to stimulate thought about aspects of plastics that have not been thoroughly covered. Answers to quantitative questions are provided in parentheses after the question.

8

9 Content Preface V 1 Introduction Historic Note Role of Plastics in Packaging Book Structure References Basic Concepts and Definitions Terminology Macromolecule Polymer Plastic Monomer Constitutional Unit Homopolymer Copolymer Polymer Nomenclature Interatomic and Intermolecular Forces in Polymers Interatomic Forces Covalent Bonds Ionic Bonds Intermolecular and Intramolecular Forces Dispersion Forces Induction Forces Dipole Forces Hydrogen Bonds Properties Determined by Chemical Composition

10 VIII Content 2.5 Categorization of Plastics References Study Questions Polymer Structure and Properties Introduction Molecular Architecture Linear Polymers Branched Polymers Cross-Linked Polymers Copolymer Structure Random Copolymers Alternating Copolymers Block Copolymers Graft Copolymers Combinations of Copolymer Types Chain Polymerization, Addition Polymers Addition or Chain Polymerization Mechanism Vinyl Polymers Free-Radical Polymerization Initiation Propagation Termination Polyethylene Polymerization Processes Other Addition Polymerization Mechanisms Molecular Configuration and Conformation Head-to-Head and Head-to-Tail Configurations of Vinyl Polymers Stereochemistry Step Polymerization, Condensation Polymers Molecular Weight and Molecular Weight Distribution Degree of Polymerization Molecular Mass (Weight) and Molecular Weight Distribution Number Average Molecular Weight Weight Average Molecular Weight Other Molecular Weight Averages Determination of MWD Effect of Molecular Weight and Molecular Weight Distribution on Flow and Mechanical Properties

11 Content 3.10 Polymer Morphology Crystallinity Polymer Orientation Degree of Crystallinity Thermal Properties Melting Temperature Glass Transition Temperature Measuring Tg Variables Affecting Tg Other Thermal Transitions Heat Capacity Heat of Fusion Thermal Conductivity Thermal Expansion Coefficient Other Dimensional Changes Dimensional Stability Mechanical Properties Tensile Properties Tear Strength Impact and Bursting Strength Other Mechanical Properties Barrier Properties Diffusion Coefficient Solubility Coefficient Permeability Coefficient Surfaces and Adhesion Surface Tension Wettability Adhesive Bond Strength Cohesive Bond Strength Blocking Friction Heat Sealing Optical Characteristics Gloss Haze Transparency and Opacity Electrical Properties Plastics Identification Using IR Spectrophotometry References Study Questions IX

12 X Content 4 Major Plastics in Packaging Branched Polyethylenes Low Density Polyethylene Ethylene Vinyl Acetate (EVA) Ethylene Acrylic Acid (EAA) Ionomers Linear Polyethylenes High Density Polyethylene (HDPE) Linear Low Density Polyethylene (LLDPE) Metallocene Polymers Property Trends in the Polyethylene Family Polypropylene (PP) PP Homopolymer Random Copolymer Polypropylene Polyvinyl Chloride (PVC) Vinylidene Chloride Copolymers (PVDC) Polystyrene (PS) Polyvinyl Alcohol (PVOH) and Ethylene Vinyl Alcohol (EVOH) Polyvinyl Alcohol Ethylene Vinyl Alcohol Nylon Polyester Polyethylene Terephthalate (PET) Glycol Modified PET, Other PET Copolymers, and PET Blends Polyethylene Naphthalate (PEN) Polycarbonate (PC) Fluoropolymers Styrene-Butadiene Copolymers Acrylonitrile Copolymers Cyclic Olefin Copolymers Liquid Crystal Polymers Conductive Polymers Thermoplastic Elastomers Biobased Plastics Cellophane Cellulosic Plastics Starch-Based Plastics

13 Content Poly(lactic acid), PLA Polyhydroxyalkanoates Biobased Polyolefins Biobased PET Other Biobased Plastics Thermosets Polymer Blends Comparison Chart of Major Plastics References Study Questions Additives and Compounding Introduction Compounding Antioxidants Heat Stabilizers UV Stabilizers Additives to Modify Surface Attractions Antiblocking Agents Slip Agents Antislip Agents Lubricants Mold Release Agents Colorants Dyes Organic Pigments Inorganic Pigments Specialty Pigments Colorants and the FDA Antifogging Agents Nucleating Agents Antistatic Agents Plasticizers Oxygen Scavengers, Desiccants, and Fragrance Enhancers Fillers and Reinforcements Antimicrobials or Biocides Nanoclays and Related Additives XI

14 XII Content 5.16 Other Additives Study Questions Adhesion, Adhesives, and Heat Sealing Adhesion Adhesives Adhesive and Cohesive Bond Strength Adhesive Bond Strength Surface Tension Solubility Parameter Viscosity Estimation of Adhesive Bond Strength Cohesive Bond Strength Types of Adhesives Reactive Adhesives Hot Melt Adhesives Solvent-Borne Adhesives Water-Borne Adhesives Pressure Sensitive and Remoistenable Adhesives Cold-Seal Adhesives UV- and E-Beam Curing Application of Adhesives Adhesive Terminology Adhesive Additives Heat Sealing Sealing Methods Bar or Thermal Sealing Impulse Sealing Band Sealing Hot Wire or Hot Knife Sealing Ultrasonic Sealing Friction Sealing Hot Gas Sealing and Contact Sealing Radiant Sealing Dielectric Sealing Magnetic Sealing Induction Sealing Solvent Sealing Heat Conduction in Multilayer Flexible Materials Hot Tack

15 Content Heat Seal Jaws Heat Seal Failure Modes Evaluation of Seals in Flexible Packaging Materials References Study Questions Extrusion, Film and Sheet Extrusion and Extruders Hopper and Feed Port Feed Section Compression Section Metering Section Mixing Devices Extruder, Screw Design and Size Dies Melt Filters Drive Mechanisms and Screw Speeds Special Designs Extrusion Temperatures Extrusion Pressures Cast Film and Sheet Cold Cast or Chill Roll Cast Process Roll Stack and Calendering Processes Quench Tank or Water Bath Process Nip Rolls and Winding Gauge Control Orientation Cast Film Dies Blown Film Blown Film Extrusion Blown Film Dies Air Rings and Internal Bubble Cooling (IBC) Collapsing Frames Nips Slitting and Winding Double-Bubble Process Stretch and Shrink Wrap Stretch Wrap Shrink Wrap Film and Sheet Coextrusion XIII