Cantor Blown Film Extrusion

An Introduction
2. Auflage 2011
ISBN: 978-3-446-42819-5
Verlag: Carl Hanser Fachbuchverlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 181 Seiten

"From hardware and materials through processing and properties, a broad coverage of blown film extrusion is presented. A primary objective of this book is to ensure a useful balance of theory and practice. The reader will find the answers to""Why?""they encounter certain effects in the blown film process so that they are better able to troubleshoot and improve their operations. At the same time, current practices and equipment are emphasized to keep readers up-to-date with the most productive and efficient technology. The companion CD-ROM, The Blown Film Extrusion Simulator, is provided to enhance the learning process. This software was developed specifically to teach blown film extrusion equipment operation and processing principles. The realistic graphic interface and intuitive operating techniques were designed to emulate actual processing methods so that learners can quickly move from the simulator to real production equipment. Throughout this book, exercises using the simulator are described to complement the methods and principles explained. Readers are encouraged to take a break from the book and spend a few minutes with the simulator to enhance their understanding of the content."

Autoren/Hrsg.

Cantor, Kirk

Inhaltsverzeichnis

1;Acknowledgements;6
2;Contents;8
3;Introduction;12
4;1Materials for Blown Film;16
4.1;1.1Polymers;16
4.1.1;1.1.1Polyethylene (PE);17
4.1.2;1.1.2Low Density Polyethylene (LDPE);17
4.1.3;1.1.3High Density Polyethylene (HDPE);19
4.1.4;1.1.4Linear Low Density Polyethylene (LLDPE);20
4.1.5;1.1.5Metallocene Polyethylene (mPE);21
4.1.6;1.1.6Polypropylene (PP);21
4.1.7;1.1.7Polystyrene (PS);22
4.1.8;1.1.8Ethylene Vinyl Acetate (EVA);23
4.1.9;1.1.9Ethylene Vinyl Alcohol (EVOH);24
4.1.10;1.1.10Polyvinyl Chloride (PVC);24
4.1.11;1.1.11Polyvinylidene Chloride (PVDC);25
4.1.12;1.1.12Polyamide (PA);25
4.1.13;1.1.13Polyurethane (PU);26
4.2;1.2Additives;26
4.2.1;1.2.1Antiblocking Agents;27
4.2.2;1.2.2Antioxidants;27
4.2.3;1.2.3Antistatic Agents;27
4.2.4;1.2.4Colorants;28
4.2.5;1.2.5Lubricants;29
4.2.6;1.2.6Reinforcements and Fillers;29
4.2.7;1.2.7Stabilizers;31
4.2.8;1.2.8Tackifiers;31
5;2Extrusion Overview;34
5.1;2.1Extruder Hardware Systems;34
5.1.1;2.1.1Drive System;36
5.1.1.1;2.1.1.1Motor;36
5.1.1.2;2.1.1.2Speed Reducer;36
5.1.1.3;2.1.1.3Thrust Bearing;37
5.1.2;2.1.2Feed System;39
5.1.3;2.1.3Screw/Barrel System;41
5.1.3.1;2.1.3.1Screw;41
5.1.3.2;2.1.3.2Barrel;43
5.1.4;2.1.4Head/Die System;44
5.1.4.1;2.1.4.1Head Assembly;45
5.1.4.2;2.1.4.2Adapter;45
5.1.4.3;2.1.4.3Breaker Plate;45
5.1.4.4;2.1.4.4Melt Filter;46
5.1.4.5;2.1.4.5Die;48
5.1.5;2.1.5Instrumentation and Control System;49
5.1.5.1;2.1.5.1Temperature Control;50
5.1.5.2;2.1.5.2Head Pressure;53
5.1.5.3;2.1.5.3Motor Current;54
5.2; 2.2Extrusion Functional Zones;55
5.2.1;2.2.1Solids Conveying;56
5.2.1.1;2.2.1.1Gravity-Induced Region;56
5.2.1.2;2.2.1.2Drag-Induced Region;57
5.2.2;2.2.2Melting;58
5.2.3;2.2.3Melt Pumping;60
5.2.4;2.2.4Mixing;62
5.2.4.1;2.2.4.1Distributive Mixing;63
5.2.4.2;2.2.4.2Dispersive Mixing;63
5.2.4.3;2.2.4.3Mixing Devices;64
5.2.5;2.2.5Degassing;66
5.2.6;2.2.6Die Forming;67
6;3Hardware for Blown Film;72
6.1;3.1Upstream Components;73
6.2;3.2Grooved Feed Throat;75
6.3;3.3Screws for Blown Film Extrusion;77
6.4;3.4Blown Film Dies;78
6.5;3.5Bubble Geometry;83
6.6;3.6Bubble Cooling;86
6.7;3.7Bubble Stabilization;91
6.8;3.8Collapsing Frames;91
6.9;3.9Haul-off;92
6.10;3.10Winders;94
6.11;3.11Film Treatment;95
6.12;3.12Line Control;96
7;4Processing;102
7.1;4.1Process Variables vs. Bubble Geometry;103
7.2;4.2Characteristic Bubble Ratios;105
7.3;4.3Process/Structure/Property Relationships;108
7.4;4.4Double Bubble Processing;110
8;5Coextrusion;112
8.1;5.1Dies;113
8.2;5.2Interfacial Instabilities;115
8.3;5.3Product Applications;116
8.3.1;5.3.1Breathable Packaging;116
8.3.2;5.3.2Shrink Film;117
8.3.3;5.3.3High Barrier Film;118
9;6Film Properties;120
9.1;6.1Tensile Strength (ASTM D882);122
9.2;6.2Elongation (ASTM D882);124
9.3;6.3Tear Strength (ASTM D1004, ASTM D1922, and D1938);124
9.4;6.4Impact Resistance (ASTM D1709, D3420, and D4272);126
9.5;6.5Blocking Load (ASTM D3354) and Coefficient of Friction (ASTM D1894);127
9.6;6.6Gel (Fisheye) Count (ASTM D3351 and D3596);128
9.7;6.7Low Temperature Brittleness (ASTM D1790);128
9.8;6.8Gloss (ASTM D2457);129
9.9;6.9Transparency (ASTM D1746);129
9.10;6.10Haze (ASTM D1003);130
9.11;6.11Density (ASTM D1505);130
9.12;6.12Melt Index (ASTM D1238);131
9.13;6.13Viscosity by Capillary Rheometry (ASTM D3835);133
10;7Troubleshooting;136
10.1;7.1Extruder Problems;137
10.1.1;7.1.1Surging;137
10.1.2;7.1.2High Melt Temperature;138
10.1.3;7.1.3Excessive Cooling;140
10.1.4;7.1.4Low Output;141
10.2;7.2Film Problems;142
10.2.1;7.2.1Melt Fracture;142
10.2.2;7.2.2Thickness Variation;143
10.2.3;7.2.3Die Lines;147
10.2.4;7.2.4Gels;148
10.2.5;7.2.5Low Mechanical Properties;149
10.2.6;7.2.6Poor Optical Properties;150
10.2.7;7.2.7Wrinkles;151
11;Appendix A: The Blown Film Extrusion Simulator;152
11.1;A.1Introduction;152
11.2;A.2Installation;153
11.3;A.3Running the Program;154
11.4;A.4Worksheet;161
12;Appendix B: Useful Equations;164
13;References;172
14;Subject Index;176

Leseproben

6 Film Properties (S. 109-110)

This chapter covers many of the most important properties measured by producers of blown film. These include mechanical, thermal, optical, physical, electrical, and rheological properties. The first five in this list apply primarily to the extruded film and the last one applies to the molten polymer inside the extruder and die. By obtaining the measurement values for these properties, manufacturers gain assurance that their resin or film will perform adequately, whether during manufacture (extrusion or conversion) or in final product form as used by the customer. It is vital that manufacturers document and maintain baseline data on the performance of their incoming materials and the film that they produce. This information provides the most efficient means for solving many problems that may arise in a manufacturing plant. Many extrusion performance issues are related to even slight modifications in raw material composition or processing properties.

These modifications are easily identified when prior baseline data is available. In addition, film performance deficiencies as measured by a reduction in some property, such as impact strength, may lead the technical staff to identify an undesirable drift in processing conditions. Another important reason for maintaining baseline data is that many customers require it. Tests for resin and film property values can be performed in-house, by an outside testing facility, or by a supplier. There are advantages and disadvantages to each. The most important consideration is the accuracy of the data collected. After that, consideration must be given to costs associated with the amount of data needed (equipment, consumables, training, labor, etc.) and the frequency of measurement required.

To suitably compare measurement values obtained at different times or locations, there must be assurance that the tests were performed under identical conditions. To accomplish this, a committee of experts in each particular subject area develops standardized test methods. The methods establish the exact conditions for all test parameters by all parties conducting tests to measure the property of interest. A major publisher of test methods covering polymer resins and plastic films is the American Society for Testing and Materials (ASTM), West Conshohocken, PA, USA. In this chapter, ASTM method reference numbers are included in parentheses at the beginning of each property description section.

Although publicly published test methods are invaluable for comparing measurement results, not all tests must conform to published standards. In many cases, processors, their suppliers, or their customers will design and perform customized tests in an attempt to best simulate actual product conditions. An example would be a grocery sack manufacturer that performs a routine quality check by loading a finished bag with a specified weight and then dropping the load onto the floor from a specified height to check for bag failure. Many in-house tests like this are designed and conducted regularly to best model actual use, shipping, or handling conditions. It is crucial, however, that test procedures are documented and followed identically every time so that results comparisons are valid.