electron beam curing of polymers - · pdf file5 crosslinking, scission, degradation, and graft...
TRANSCRIPT
CONTENTS
1 INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . 1
2 SUMMARY .........................
Market and Producers ................... Equipment ........................
Economics ........................ Technical ........................
3 INDUSTRY STATUS .....................
Markets ......................... Equipment Suppliers ...................
Wire and Cable ...................... Shrink Tubing ...................... ShrinkFilm .......................
Coatings ......................... Textiles ......................... Speciality Applications .................
Future Developments ...................
4 FUNDAMENTALS OF ELECTRON CURING OF POLYMERS .......
Basic Characteristics of High Energy Radiation ......
Radiation Units and Definitions .............
Ionization ........................ Basic Techniques of Ionization and Excitation ......
XRays ......................... GammaRays ....................... Accelerated Electrons .................
Penetration ....................... Linear Energy Transfer (LET) ...............
Radiation Chemical Yields (,,Gw Value) ..........
Dosimetry ........................ Basic Chemical Effects .................. Free Radical Reactions ..................
5 CROSSLINKING, SCISSION, DEGRADATION, AND GRAFT POLYMERIZATION .....................
Crosslinking and Scission ................ Related Effects of Crosslinking and Scission ...... Crosslinking Theory ..................
Degradation ....................... Graft Polymerization ...................
3
3 6
10 12
17
17 20 24 25 25 26 27 27 28
31
33 35 38
40 43 44 47 51 54 56 62 65
69
72 78 82 83 86
Vii
6 ACCELERATED ELECTRON BEAM EQUIPMENT ............ 95
Insulating Core Transformer ................ 95 Dynamitron ........................ 109 Curtain and Planar Beam Accelerators ........... 117 Resonant Transformer ................... 126 Van de Graaff Electrostatic Accelerator .......... 130 Traveling Wave Linear Accelerators ............ 134 Other Very High Voltage Accelerators ........... 137 Radiation Protection and Shielding for Electron
Accelerators ....................... 139 Summary of Industrial Electron Beam Accelerators ..... 151
7 INDUSTRIAL APPLICATIONS OF ELECTRON BEAM RADIATION .... 159
Raychem Corporation .................... 167
W. R. Grace and Company, Cryovac Division ......... 175
Ford Motor Company--Electrocure@ Process ......... 182
Deering Milliken Company ................. 185
Western Electric/Bell Laboratories ............ 192
Radiation Vulcanization of Rubber ............. 200
Surface Coatings and Adhesives .............. 203
8 ECONOMICS OF ELECTRON BEAM CURING OF POLYMERS ....... 233
Electron Beam Accelerator Sizing ............. 234
Accelerator Processing and Capital Costs ......... 234
Electron Beam Versus Thermal Curing ............ 243
Synthetic Rubber Sheet Vulcanization--EB Versus Rotocure@ .................... 243
Polyethylene Tubing--EB Crosslinking .......... 245
Flocking Adhesives--EB Versus Thermal Curing ...... 248
Polyethylene Insulation on Cable--EB Versus Continuous Vulcanization ................ 250
Comparative Economics of EB, Thermal, and Ultraviolet Systems ................... 257
CITEDREFERENCES........................ 261
PATENTREFERENCES BYCOMPANY. . . . . . . . . . . . . . . . . . 281
viii
ILLUSTRATIONS
2.1
2.2
2.3
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5.1
5.2
5.3
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
Schematic Outlines of Industrial Polymer Irradiation Processes .................
Comparison of Scanned Electron Beam Accelerator and Linear or Planar Electron Curtain
Accelerator ......................
Schematic Mechanism for Crosslinking ..........
Electromagnetic Spectrum of Radiation .........
Basic Techniques for Radiation Processing of Polymers ......................
Typical X Ray Spectrum .................
Distribution of Ions and Excited Molecules in the Track of a Fast Electron .............
Dose-Depth Curve in Water for Electrons ........
Average Linear Energy Transfer (LET) for Electrons inWater .......................
Approximate Values of Linear Energy Transfer and Ion Density in Water ...............
Applications of Radiation Dosimetry ..........
Pathways in Radiation Chemistry ............
Mechanism of Crosslinking and Endlinking ........
Polyethylene Crosslinking ...............
Crosslink and Endlink Networks .............
Typical Electron Processing Systems ..........
Insulating Core Transformer ..............
Schematic Diagram of a Three-Phase ICT Power Supply ...................
Voltage-Stabilizing Circuit for an ICT Power Supply ...................
Electron Accelerator and Section of Tube ........
Electron Beam Scanner .................
Irradiation of Cable by Three Accelerators . . l l l l .
High Energy Integral ICT Electron Accelerator .....
5
8
14
287
41
42
46
48
52
53
58
68
73
75
77
97
98
99
100
102
103
105
106
iX
6.9 Electron Penetration Curves . . . . . . . . . . . . . . . 107
6.10
6.11
6.12
6.13
6.14
6.15
6.16
6.17
6.18
6.19
6.20
6.21
6.22
6.23
6.24
6.25
6.26
6.27
6.28
6.29
6.30
6.31
Basic Dynamitron Schematic ............... 112
Typical System Arrangements for Dynamitron III ..... 114
Curtain Electron Beam Processor Schematic ........ 118
Electrocurtain@Accelerator ............... 119
Product Handling Configurations, Electrocurtain@ .... 121
Broad Beam Electron Gun ................. 122
Comparison of Planar Electron Beam Gun with SweptBeam ....................... 123
Cold Cathode Broad Beam Electron Gun Pulsed-Plasma Emission of Electrons .......... 125
Resonant Transformer and Electron Accelerator ...... 128
Principal Circuit Elements of Resonant Transformer ...................... 129
Van de Graaff 2 MeV Electron Accelerator ........ 131
Operating Principle of a Van de Graaff Electron Accelerator .................. 133
Linear Accelerator with RF Power Feedback ........ 136
In-Line Electron Radiation Processing System ...... 144
Energy Range for Various Absorbers ........... 145
Electron Range Versus Energy for Several Absorbers ....................... 146
Attenuation in Lead of X Rays Produced by Potentials of 250 to 400 Kilovolts ........... 147
Attenuation in Lead of X Rays Produced by Potentials of 500 to 2,000 Kilovolts Constant Potential ................... 148
Attenuation of Electron Energy in Concrete ....... 149
Direct and Indirect Type Accelerators .......... 153
Toroidal Electron Beam Accelerator System ........ 156
Magnetically Turned Electrons .............. 157
X
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
Schematic of Memory Effect of Irradiated
Polymer . . . . . . . . . . . . . . . . . . . . . . . . 160
Schematic of Process for Making Expanded
Shrinkable Polyethylene Tubing . . . . . . . . . . . . 173
Methods of Producing Film Having Improved Shrink Energy . . . . . . . . . . . . . . . . . . . . . 180
Application of Electrocure@ Process on Automotive Instrument Panels . . . . . . . . . . . . . 184
Two Types of Composite Plastic-Textile Wire Insulation for Which a Single Material, Irradiated Polyvinyl Chloride, Will Be Substituted . . . . . . . . . . . . . . . . . . . . . . 193
"Figure 8" and Double-Side Irradiation of Conductor . . . . . . . . . . . . . . . . . . . . . 195
Four-Side and Three-Side Irradiation ofCable . . . . . . . . . . . . . . . . . , . . . . . 196
Comparison of Floor Space Requirements for Conventional Curing and Radiation Curing . . . . . . . 202
Schematic Layout of Radiation Cure on Sheet Rubber . . . . . . . . . . . . . . . . . . . . . 204
Bixby International Corporation Electrocurtair# FlockLine . . . . . . . . . . . . . . . . . . . . . . 208
8.1 Electron Beam Penetration Capability . . . . . . . . . . 235
8.2 Processing Cost Rates Versus
8.3
8.4
8.5
8.6
8.7
8.8
Electron Beam Power . . . . . . . . . . . . , . . . . . 240
Capital Costs Versus Electron Beam Power . . . . . . . . . . . . . . . . . . 241
Capital Cost Versus Power and Time . . . . . . . . . . . 242
Thermal Efficiency of Electron Beam Cure Versus Thermal Cure . . . . . . . . . . . . . . . . . . 244
Schematic of an Electron Beam Irradiation System for Insulated Electrical Cable . . . . . . . . . . . . 254
Schematic of Catenary Continuous Vulcanizing System for Insulated Electrical Cable . . . . . . . . . . . . 255
Power Consumption--Thermal, UV, and Electron Beamcuring...................... 259
ILLUSTRATIONS
xi
TABLES
2.1 Major Electron Beam Processing Applications . . . . . . 3
2.2 Major Suppliers of Electron Beam Equipment . . . . . . 9
2.3 Summary Comparison of Capital and Operating Costs of Electron Beam Versus Thermal Curing of Polymers . . . . . . . . . . . . . . . . . . 11
3.1 U.S. Industrial Electron Beam Irradiation Processors . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Other U.S. Companies in Research and Development of Electron Beam Radiation of Polymers....................... 19
3.3 Companies in Electron Beam Curing of Polymers Outside the United States . . . . . :. . . . . . . . 21
3.4 Suppliers of Electron Beam Equipment . . . . . . . . . 22
3.5 In-Use Electron Accelerators . . . . . . . . . . . . . 23
3.6 Radiation Service Facilities . . . . . . . . . . . . . 24
4.1 Energy Equivalents . . . . . . . . . . . . . . . . . . 39
4.2 Typical Radiation Sources, Energy and Penetration . . . . . . . . . . . . . . . . . . . . . 50
4.3
4.4
4.5
5.1
5.2
5.3
5.4
5.5
5.6
6.1
Typical Radiation-Crosslinkable Polymers . . . . . . . 56
Dosimetry Methods . . . . . . . . . . . . . . . . . . . 59
Various Dosimetry Systems for Radiation Processing . . . . . . . . . . . . . . . . . . . . . . 61
Crosslinking Versus Degradation in Irradiated Polymers . . . . . . . . . . . . . . . . . 70
Correlation of Polymer Properties with Effects of Radiation . . . . . . . . . . . . . . . . . 72
Approximate Crosslink and Scission Yields of Some Radiation Crosslinked Polymers . . . . . . . . . 76
Irradiation-Induced Changes in Polyethylene . . . . . . 78
Gas Evolution of Radiated Polymers . . . . . . . . . . 79
Prominent Graft Polymers . . . . . . . . . . . . . . . 92
Facility Requirements of Electron Processing Systems . . . . . . . . . . . . . . . . . . . . . . . 110
xii
TABLeS
6.2
6.3
6.4
Dynamitron Performance Ratings . . . . . . . . . . . . .
Typical Doses for Various Processes,
and Methods for Estimating Process Rates . . . . . . .
Typical Characteristics of Varian's Industrial Linear Accelerators . . . . . . . . . . . .
115
116
138
6.5 Dose-Limiting Recommendations . . . . . . . . . . . . . 140
6.6 Examples of Biological Response in Human Organs after External Partial Body Irradiation . . . . . . . . . . . . . . . . . . . . . . .
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
Radiation Applications in Use . . . . . . . . . . . . .
Summary of Electron Beam Polymer Radiation Applications . . . . . . . . . . . . . . . .
Advantages and Disadvantages of Electron Beam Curing . . . . . . . . . . . . . . . . .
Raychem Corporation--Radiation Crosslinked Polymers Patent Summary . . . . . . . . . . . . . . . . . . . .
W. R. Grace and Company--Radiation Crosslinked Polymers PatentSummary . . . . . . . . . . . . . . . . . . . .
Ford Motor Company--Radiation Polymerizable Coatings Patent Summary . . . . . . . . . . . . . . . . . . . .
Deering Milliken Research Corporation--Radiation Grafting of Polymers to Textiles for Soil Release and Durable Press Patent Summary . . . . , . . . , . . . . . . . . . . .
Wire and Cable Insulation, and Rubber Patent Summary . . . . , . . . . . . . . . . . . . . .
Radiation Crosslinked Materials for Wire and Cable Insulation . . . . . . . . . . . . . . . . .
Suppliers of Radiation Curable Resins and Coatings . . . . . . . . . . . . . . . . . . . . .
Suppliers of Radiation Curable Compounds . . . . . . . .
142
163
164
166
168
177
186
190
198
199
209
212
Xiii
7.12
7.13
7.14
7.15
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
Electron Beam Curing of Polymers, Resins, and Coatings
United States Patent Summary . . . . . . . . . . . . .
Electron Beam Curing of Polymers, Resins, and Coatings European Patent Summary . . . . . . . . . . . . . . .
Electron Beam Curing of Polymers, Resins,
and Coatings Japanese Patent Summary . ti . . . . . . . . . . . . .
Older Japanese Patents on Irradiation Hardening Polymerization . . . . . . . . . . . . . . .
Sizing and Selection of Electron Beam Units . . . . . .
Processing Cost Analyses: Increasing
Voltage-Constant Current . . . . . . . . . . . ; . . .
Processing Cost Analyses: Constant Voltage-Increasing Current . . . . . . . . . . . . . .
Cost Comparison Between Radiation Cure and Thermal Rotocure@ for EPDM Sheet . . . . . . . . . . .
Economics of Radiation Crosslinking of Polyethylene Tubing . . . . . . . . . . . . . . . . .
Cost Comparison Between Radiation and Thermal Curing of Flocking Adhesive . . . . . . . . .
Energy Cost Comparison Between Radiation and Continuous Vulcanization for Crosslinking of Polyethylene in Wire Insulation . . . . . . . . . . .
Cost Comparison Between Radiation and Continuous Vulcanization for Crosslinking Polyethylene Insulation on Cable . . . . . . . . . . .
Assumptions for Cost Comparison Between Radiation and Continuous Vulcanization for Crosslinking Polyethylene Insulation on Cable . . . . . . . . . . .
Comparative Economics of High Speed Curing Systems for One Mil Pigmented Coating on One Side of a 48 Inch Plastic Web . . . . . . . . . .
213
223
227
230
236
237
238
246
247
249
251
252
253
258
xiv