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The Mixing of Rubber
The Mixing of Rubber
Edited by
Richard F. Grossman HALSTAB Hammond Indiana USA
ID,11 SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.
First edition 1997
© 1997 Springer Science+Business Media Dordrecht Originally published by Chapman & Hall in 1997 Softcover reprint of the hardcover 1 st edition 1997 Typeset in 10/12 Palatino by Florencetype Ltd, Stoodleigh, Devon
ISBN 978-94-010-6460-6 ISBN 978-94-011-5824-4 (eBook) DOI 10.1007/978-94-011-5824-4
Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page.
The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made.
A catalogue record for this book is available from the British Library
§Printed on permanent acid-free text paper, manufactured in accordance with ANSI/NISO Z39.48-1992 and ANSI/NISO Z39.48-1984 (Permanence of Paper).
Contents
List of contributors xi Preface Xlll
List of trade names xv List of acronyms XVI
1 Mixing machinery for rubber 1 Michael A. Melotto 1.1 Introduction 1 1.2 Two-roll mills 2 1.3 Internal batch mixers 4 1.4 Continuous mixers 8 1.5 Development of the Banbury mixer 9 1.6 Operating variables 13
1.6.1 Ram pressure 13 1.6.2 Rotor speed 15 1.6.3 Batch size 19 1.6.4 Coolant temperature 20
2 Mixing cycles and procedures 25 Richard F. Grossman 2.1 Cost of internal mixing 25 2.2 Unit operations in mixing 26 2.3 Single-pass versus multiple-pass mixing 30 2.4 Types of mix cycle 32
2.4.1 Late oil addition 35 2.4.2 Upside-down mixing 37 2.4.3 Sandwich mixes 40
2.5 Analysis of changes to the mix procedure 43 References 48
vi Contents
3 Mill mixing 49 Richard F. Grossman 3.1 Introduction 49 3.2 Acceleration of first-pass compound 49 3.3 Mill mixing of specialty compounds 54 3.4 Acceleration in line with internal mixing 56
4 Quality control and the mixing process 57 Richard F. Grossman 4.1 Introduction 57 4.2 Testing of raw materials 57
4.2.1 Elastomers as raw materials 58 4.2.2 Fillers 59 4.2.3 Plasticizers and process oils 60 4.2.4 Small ingredients 60
4.3 Control of composition 61 4.4 Tracking the mix cycle 64 4.5 Compound testing 66
5 Statistical process control for industrial mixing 71 R.J. Del Vecchio 5.1 Introduction 71 5.2 Basic SPC charting 72 5.3 Rheometer data and its meaning 76 5.4 A case history 78 5.5 Summary 88 5.6 Mixing control software 89
References 90
6 Additives that affect mixing 91 Robert F. Ohm 6.1 Introduction 91 6.2 Peptizers in natural rubber 91
6.2.1 Effects of temperature 92 6.2.2 Effects of time 92 6.2.3 Effects of use level 94 6.2.4 Effects of other additives 94
6.3 Peptizers in SBR 96 6.4 Peptizers in sulfur-containing polymers 96 6.5 Additives to increase viscosity 98 6.6 Preventing unwanted chemical reactions 100
6.6.1 Filler treatments 101 6.6.2 Bin storage problems 102 References 102
Contents vii
7 Operation and maintenance of mixing equipment 103 Steven R. Salma 7.1 Inspection of Banbury mixers 103
7.1.1 Inspection at the mezzanine level 104 7.1.2 Inspection of the Banbury platform 107
7.2 Mixer maintenance and lubrication 108 7.2.1 Each time the mixer is started 108 7.2.2 Once per shift 108 7.2.3 Once per day 109 7.2.4 Once per week 110 7.2.5 Once per month 110 7.2.6 Every six months 111
7.3 Anticipating required service 111 7.4 Dust stop maintenance 111 7.5 SSA dust stops 119
7.5.1 Assembly 119 7.5.2 Lapping 120 7.5.3 Running 121
7.6 Banbury mixer: hydraulic dust stops 121 7.6.1 Assembly 121 7.6.2 Run-in 121 7.6.3 Lapping 122 7.6.4 Production 122 7.6.5 Flushing 122 7.6.6 Other points 122 7.6.7 Hydraulic pressure ratio 123 7.6.8 O-ring assembly 123
8 Mixing procedures for specific compounds 125 Richard F. Grossman 8.1 Introduction 125 8.2 EPDM expansion joint cover 125 8.3 Expansion joint intermediate layer 127 8.4 Traffic counter treadle cover 128 8.5 SBR/IR belt cover 129 8.6 EPDM low voltage electrical connector 131 8.7 Peroxide-cured black-filled EPDM compounds 132 8.8 EPDM concrete pipe gasket 133 8.9 SBR insulation 134 8.10 Injection-molded NBR gasket 135 8.11 CR/SBR blend 137 8.12 Low durometer CR/SBR blend 139 8.13 CR specification compounds 140 8.14 Charge-dissipating CR tubing 141
viii Contents
8.15 Nonblack CR for injection molding 143 8.16 Hard rubber industrial wheel 144 8.17 High durometer NBR masterbatch 145 8.18 NBR/PVC cable jacket 146 8.19 NBR/PVC/SBR blend 148 8.20 Butyl masterbatch 148 8.21 Butyl masterbatch, heat interacted 150 8.22 Chlorobutyl/NR blend 151 8.23 CSM cord jacket 151 8.24 Nonblack millable urethane 154 8.25 ECO molding compounds 155 8.26 Polyacrylate shaft seal 157 8.27 XLPE insulation 158 8.28 FKM molding compound 159 8.29 Silicone spark plug boot cover 161
9 Mixing wire and cable compounds 163 Allen C. Bluestein 9.1 Introduction 163
9.1.1 Developments since the 1960s 164 9.1.2 Some major changes 164
9.2 Tempered water 165 9.3 Power-controlled mixing 168 9.4 Energy conservation 169
References 170
10 Mixing ethylene-propylene diene rubber 173 Charanjit S. Choda and Emmanuel G. Kontos 10.1 Introduction 173 10.2 Background of EPDM development 173 10.3 Composition of EPDM elastomers 174 10.4 Variables in EPM and EPDM elastomers 175
10.4.1 Average molecular weight 176 10.4.2 Molecular weight distribution 176 10.4.3 Ethylene/propylene ratio 176 10.4.4 Type of diene 176 10.4.5 Diene level 177
10.5 How processing relates to structure and rheology 178 10.6 Practical guidelines for mixing EP elastomers 179
10.6.1 Using internal mixers 179 10.6.2 Using two-roll mills 183
10.7 Summary 184 References 185
11 Mixing of tire compounds Martin J. Hannon 11.1 Introduction 11.2 Rework 11.3 Phase mixing
Contents
11.4 Natural rubber: viscosity reduction 11.S Measurement of mixing efficiency
References
12 Mixing fluoroelaslomer (FKM) compounds Richard Mastromatteo 12.1 Introduction 12.2 Special considerations 12.3 Raw materials 12.4 Typical formulations 12.S Internal mixing 12.6 Mill mixing 12.7 Summary 12.8 Accounting methods
13 Continuous mixing Gene J. Sorcinelli 13.1 The Farrel continuous mixer 13.2 Operating principles of the FCM 13.3 Commercial applications for the FCM 13.4 The Farrel mixing venting extruder (MVX)
14 Evaluating the performance of internal mixers L.N. Valsamis, E.L. Canedo and G.S. Donoian 14.1 Introduction and literature review 14.2 Designing the rotor 14.3 Analysis of dispersive mixing 14.4 Results from synchronous rotors
References
Appendix Unit conversion tables and factors A.1 Conversion between Fahrenheit and Celsius A.2 Conversion of English units to metric units
Index
ix
187
187 188 191 194 199 200
201
201 202 204 20S 20S 207 207 208
211
211 211 216 217
221
221 223 224 229 234
237 238 239
241
Contributors
Allen C. Bluestein Berlington Associates, Inc. 232 Burlington Ave. Spotswood, NJ 08884
E. L. Canedo Farrel Corporation 25 Main St. Ansonia, CT 06401
Charanjit S. Chodha Uniroyal Chemical Co. Spencer St. Naugatuck, CT 06770
R. J. Del Vecchio Technical Consulting Services 3 John Matthews Road Southborough, MA 01772
G. S. Donoian Farrel Corporation 25 Main St. Ansonia, CT 06401
Richard F. Grossman Halstab 1013 Oriente Ave. Wilmington, DE 19807
Martin J. Hannon Uniroyal Chemical Co. Spencer Street Naugatuck, CT 06770
xii
Emmanuel G. Kontos Uniroyal Chemical Co. Spencer St. Naugatuck, CT 06770
Richard Mastromatteo Cri-Tech, Inc. 85 Winter St. Hanover, MA 02339
Michael A. Melotto Farrel Corporation 25 Main St. Ansonia, CT 06401
Robert F. Ohm R. T. Vanderbilt Co., Inc. 30 Winfield St. Norwalk, CT 06855
Steven R. Sa1ma Farrel Corporation 25 Main St. Ansonia, CT 06401
Gene J. Sorcinelli Farrel Corporation 25 Main St. Ansonia, CT 06401
L. N. Valsamis Farrel Corporation 25 Main St. Ansonia, CT 06401
Contributors
Preface
What if this mixture do not work at all? Shakespeare, Romeo and Juliet
So says Juliet in Act IV, scene iii; if the mixture is a rubber compound, whether it works or not will depend on several premises:
• That a composition has been developed whose properties, as measured experimentally, give rise to the expectation that it will work.
• That raw materials have been obtained whose properties correspond in adequate measure to those of the samples used in formulation development.
• That the composition may be consistently mixed to suitable homogeneity by those skilled in the art, with efficiency commensurate with the added value commanded in the marketplace.
• That the mixed compound may similarly be fabricated into marketable articles.
The mixing of rubber is concerned mainly with the third of the above considerations. Nevertheless, mixing cannot be isolated from formulation, raw material control and the influence of further processing. These topics are therefore considered in terms of their effects on mixing of rubber compounds.
Only in the tire sector of the rubber industry is mixing itself considered a technical specialty. In most other areas, the manufacturer of rubber articles will generally have strong expertise in further processing: extrusion, calendering, molding, etc. Leading manufacturers will typically invest in the most modem processing equipment. And they will generally invest in acquiring the materials science underlying their specialities. Often, however, they will persist with obsolete mixing equipment and mixing procedures that are historic rather than ingenious.
xiv Preface
Innovation in mixing is associated with the tire industry, some equipment manufacturers, certain custom compounders, a small number of manufacturers in specialized fields, and some of their suppliers. Few in any of these categories are willing to discuss their programs with the industry at large. I would like to thank the authors who have, in every case, been able to convince the management of their companies of the long-range benefits of education.
Richard F. Grossman Wilmington, Delaware
November 1996
Trade names
Altax, Amax, Cumate, Leegen, Tuads, Vanax, Vanfre, Vanox, and Vanplast are registered in the United States to the R. T. Vanderbilt Company, Inc. Banbury, FCM, MVX, and ST (synchronous technology) in reference to internal mixer rotors, are registered to Farrel Corporation. Plioflex and Wingstay are trade names of Goodyear Tire & Rubber Co., Carbowax of Union Carbide Corp., HiSil of Pittsburgh Plate Glass Co., and Renacit of Bayer. Hypalon, Vamac, and Viton are registered by E. I. duPont de Nemours, Thiokol by Morton International, Factice by Harwick Corp., AgeRite and Stalite by the B. F. Goodrich Company, Royalene by Uniroyal Chemical Co., Pepton by Shaw Chemical, and Dyphos by Halstab Division, The Hammond Group.
Acronyms
ACN BR CP CPE CR CSM CV DBP DCPD DOP ECO ENB EPDM EPM ETU EVA FCM FEF FKM GPF HAF HD ILPA IR ISAF
LDPE MBT MBTS MPT MW
acrylonitrile butadiene rubber chemical peptizer chlorinated polyethylene chloroprene rubber chlorosulfonated polyethylene continuous vulcanization dibutyl phthalate dicydopentadiene di-2-ethylhexyl phthalate epichlorohydrin copolymer ethylidene norbornene ethylene-propylene-diene terpolymer ethylene-propylene copolymer ethylene thiourea ethylene-vinyl acetate copolymer Farrel continuous mixer fast extruding furnace black, ASTM N500 series fluoroelastomer general-purpose furnace black, ASTM N600 series high abrasion furnace black, ASTM N300 series hexadiene internally lubricating processing aid isoprene rubber intermediate super abrasion furnace black, ASTM N200 series low density polyethylene mercaptobenzothiazole benzothiazyl disulfide Monsanto processability tester molecular weight
MWD NBR NPD NR ODR PE phr PPDC PTFE PVC QC SBR SCR SPC SRF TBBS TETD TMTD TPE TQM XLPE
Acronyms
molecular weight distribution nitrile-butadiene rubber number of passage distribution natural rubber oscillating disk rheometer polyethylene parts per hundred rubber piperidinium pentamethylene dithiocarbamate polytetrafluoroethylene polyvinyl chloride quality control styrene-butadiene rubber silicon-controlled rectifier statistical process control semireinforcing furnace black, ASTM N700 series t-butylbenzothiazole sulfenamide tetraethylthiuram disulfide tetramethylthiuram disulfide thermoplastic elastomer total quality management cross-linkable polyethylene
xvii
