REFERENC

E BOOKS

OF TEXTI

LES TECH

NOLOGIES

the non

wovens

by G

iova

nni T

anch

is

Ministero dello Sviluppo Economico

Collections Edited By Fondazione Acimit ″STRATEGIES OF INDUSTRIAL ECONOMY″ THE TEXTILE MACHINERY INDUSTRY IN ITALY: STRATEGIC, COMMERCIAL, FINANCIAL BEHAVIOURS (April 1997) THE TEXTILE MACHINERY INDUSTRY IN THE 2000’s: HYPOTHESIS, SIMULATION GAMES, TREND OF THE RELATED SCENARIOS (November 1997) THE CRISIS OF THE ASIAN TEXTILE SECTOR ON THE VERGE OF THE 2000’s (November 1998) TEXTILE MACHINES: THE COMPETITION OF THE EMERGING COUNTRIES (December 1999) THE TECHNOLOGICAL EVOLUTION OF THE CHINESE TEXTILE MACHINERY INDUSTRY (February 2001) THE ITALIAN TEXTILE MACHINERY INDUSTRY: COMPETITIVE STRATEGIES, INTERNATIONAL POSITION AND ECONOMIC PERFORMANCES (December 2001) THE WORLD TEXTILE MACHINERY INDUSTRY: COMMERCIAL FLOWS AND MARKET SHARES. YEARS 1995 - 2001 (May 2003) THE TEXTILE MACHINERY MARKET IN CHINA (November 2004) ″PUBLICATIONS FOR THE SCHOOLS″ THE ITALIAN TEXTILE MACHINERY INDUSTRY, TODAY: CHARACTERISTICS, RAW MATERIALS, TECHNOLOGIES (December 1999), out of print NOTEBOOKS OF TEXTILE TECHNOLOGY: WEAVING (3rd edition, January 2003), available on CD-Rom NOTEBOOKS OF TEXTILE TECHNOLOGY: KNITTING (3rd edition, October 2003), available on CD-Rom NOTEBOOKS OF TEXTILE TECHNOLOGY: FINISHING (3rd edition, November 2006), available on CD-Rom NOTEBOOKS OF TEXTILE TECHNOLOGY: COTTON AND WOOLLEN SPINNING (2nd edition, November 2004), available on CD-Rom NOTEBOOKS OF TEXTILE TECHNOLOGY: MAN-MADE FIBRES (2nd edition, June 2006), available on CD-Rom NOTEBOOKS OF TEXTILE TECHNOLOGY: THE NONVOWENS (1st edition, April 2008), available on CD-Rom

edited in co-operation with by Giovanni Tanchis

First edition: April 2008

Any reproduction, even partial and by whichever means, infringes copyright and is liable to prosecution by law in accordance with

international conventions.

Foreword I am pleased to present the sixth volume of a series of �Notebooks� on textile machines technologies, which Foundation ACIMIT worked out for the use of textile institutes and of universities with textile engineering degree courses. The subject of this Notebook are the machines for the production of nonwovens, a market segment of utmost importance and at the same time in rapid expansion within the Italian textile machinery industry. The need to prepare real textbooks for textile schools dates back already to the year 1999, after a specific invitation by Italian universities and by textile technical institutes. Thanks to the work started at that time, which saw the enthusiastic contribution of a group of teachers of these textile technical institutes, Fondazione ACIMIT succeeded in putting at the disposal of the Italian students 5 Notebooks on the most up-to-date technologies in the sectors of spinning, weaving, knitting, man-made fibres and finishing. With present Handboook on nonwovens, the publications of Fondazione ACIMIT are enriched with a treatise of certain interest for a sector, which in these years has been characterized by a rapid technological development. The success of these publications (their total circulation exceeds today 18.000 copies), as well as the relations maintained with the major textile schools and universities abroad, also convinced our Fondazione of the opportunity to translate the Notebooks into English, Chinese and Arab languages, so as to enable their distribution through CD-ROMs also in countries which enjoy a well-established textile tradition. We would appreciate any suggestion and amendment coming from operators involved in this subject (teachers, students, factory technicians, etc.), in order to enhance the scope and use of these publications. April 2008 Paolo Banfi, President of Fondazione ACIMIT

Acknowledgements

Fondazione ACIMIT feels bound to thank the textile institution Centro Tessile Cotoniero in Busto Arsizio (Varese), in the persons of General Manager Dr. Grazia Cerini and of Chief Engineer Dr. Gabriella Fusi, who took on the assignment to accomplish this Notebook �The nonwovens�.

*** The writing up of this book was entrusted by Centro Tessile Cotoniero to Dr. Gianni Tanchis, to whom Fondazione ACIMIT wish to express heartfelt thanks for the valuable time and deep enthusiasm expended in its realization.

*** Gianni Tanchis - Graduated in biology at the Università degli Studi in Milano - As a biologist, he collaborated with the aquatic microbiology laboratories of IRSA in

Brugherio, of CCR in Ispra and with the microbiology laboratories of Ospedale Galmarini in Tradate.

- Since 1998, he was in charge with the textile microbiology laboratory of Centro Tessile Cotoniero e Abbigliamento, with the task of developing the testing activities of the laboratory; these included tests on individual protection devices against biological risk, tests on non-active medical devices for operating rooms, tests for the assessment of the antibacterial and antimycotic activity of textile materials, tests on the microbiological state of textile surfaces and of processing water in industrial laundries.

- Author of numerous articles on account of various textile magazines concerning the description and the application of new international testing methods for the assessment of the antimicrobic efficacy of the textile materials, the application of new biotechnologies in the textile sector and the properties both of individual protection devices against biological risks and of medical non-active textile-based devices.

INDEX Chapter 1 � Generalities .......................................................................................11 1.1 Definition of the term �nonwoven� .............................................................................. 11 1.2 Historical outline .......................................................................................................... 12 1.3 Application sectors ....................................................................................................... 14 Chapter 2 � Production processes........................................................................17 2.1 The raw materials ......................................................................................................... 17 2.1.1 Properties of the fibres.................................................................................................. 22 2.1.2 The evolution of the fibres............................................................................................ 24 2.2 The manufacture of nonwovens ................................................................................... 27 2.3 The production of drylaid webs.................................................................................... 29 2.3.1 Fibre opening................................................................................................................ 29 2.3.2 Fibre oiling ................................................................................................................... 38 2.3.3 Carding ......................................................................................................................... 39 2.3.4 Garnett machine............................................................................................................ 44 2.3.5 Carding machine........................................................................................................... 45 2.4 Folding systems ............................................................................................................ 49 2.5 Drawing machines ....................................................................................................... 50 2.6 Web formation by vertical folding ............................................................................... 50 2.7 The airlaying process.................................................................................................... 51 2.7.1 Characteristics of raw material and fibre preparation .................................................. 52 2.7.2 Technology of airlaying processes ............................................................................... 55 2.7.3 Evolution of airlaying processes .................................................................................. 63 2.7.4 Air flow and fibre dynamics in airlaying processes ..................................................... 64 2.7.5 Web bonding ................................................................................................................ 65 2.7.6 Physical properties and practical applications of airlaid nonwovens ........................... 66 2.8 Production of wetlaid webs .......................................................................................... 67 2.8.1 Raw materials ............................................................................................................... 69 2.8.2 Preparation of raw materials......................................................................................... 73 2.8.3 Technology of web forming process ............................................................................ 74 2.8.4 Bonding systems........................................................................................................... 77 2.8.5 Finishing treatments ..................................................................................................... 79 2.9 Web formation by direct spinning................................................................................ 79 2.9.1 Raw materials ............................................................................................................... 80 2.9.2 Nonwoven production by direct spinning .................................................................... 83 2.9.3 Extrusion spinning........................................................................................................ 84 2.9.4 Spunbond production systems...................................................................................... 87 2.9.5 Process variables ......................................................................................................... 93 2.9.6 Structure and properties of spunbond nonwovens........................................................ 97 2.10 Production of meltblown nonwovens ........................................................................... 99 2.10.1 Process technology ..................................................................................................... 100 2.10.2 Studies on process parameters.................................................................................... 100 2.10.3 Characteristics and properties of meltblown nonwovens ........................................... 102

2.11 Composite fabrics and other extrusion processes....................................................... 103 2.11.1 Coform®..................................................................................................................... 103 2.11.2 Flashspinning.............................................................................................................. 103 2.11.3 Electro-spinning ......................................................................................................... 104 2.11.4 Centrifugal spinning system ....................................................................................... 107 2.11.5 Future trends ............................................................................................................... 107 Chapter 3 � Bonding methods ............................................................................108 3.1 Mechanical bonding ................................................................................................... 108 3.1.1 Stitchbonding or needlebonding ................................................................................ 108 3.1.2 Recent developments in stitchbonding....................................................................... 116 3.2 Needlepunching ....................................................................................................... 117 3.2.1 Technology of the needlepunching process................................................................ 122 3.3 Bonding by hydroentangling ...................................................................................... 127 3.3.1 Technology of the hydroentangling process ............................................................. 135 3.3.2 Multilayer (composite) hydroentangled nonwovens .................................................. 143 3.4 Thermobonding .......................................................................................................... 144 3.4.1 Materials ..................................................................................................................... 145 3.4.2 Calender (contact) bonding ....................................................................................... 147 3.4.3 “Through-air” and impingement bonding ................................................................ 152 3.4.4 Ultrasound bonding .................................................................................................... 154 3.5 Chemical bonding....................................................................................................... 155 3.5.1 Chemical binders ........................................................................................................ 156 3.5.2 Mechanism of chemical bonding................................................................................ 161 3.5.3 Binder application methods ........................................................................................ 163 3.5.4 Drying......................................................................................................................... 168 Chapter 4 � Finishing of nonwovens..................................................................172 4.1 Wet finishing treatments............................................................................................. 172 4.2 Chemical finishes ....................................................................................................... 174 4.2.1 Methods for chemical finishes application................................................................. 175 4.3 Mechanical finishing treatments................................................................................. 178 4.4 Emerging technologies ............................................................................................... 182 4.5 Cutting and winding ................................................................................................... 183 Chapter 5 � Characterization of nonwovens.....................................................194 5.1 Norms for nonwoven analysis .................................................................................... 194 5.1.1 Norms for medical nonwovens................................................................................... 194 5.1.2 Norms for air filtration ............................................................................................... 194 5.2 Characterization of nonwoven structure � Generalities ............................................. 194 5.3 Characterization of bonding structure ........................................................................ 196 5.3.1 Needlepunched nonwovens ........................................................................................ 196 5.3.2 Wetlaid nonwovens .................................................................................................... 197 5.3.3 Stitchbonded nonwovens............................................................................................ 197 5.3.4 Thermobonded nonwovens ........................................................................................ 198 5.3.5 Chemically bonded nonwovens.................................................................................. 198 5.4 Measurement of basic parameters .............................................................................. 198

Chapter 6 � Nonwoven applications ..................................................................205 6.1 The products ............................................................................................................... 205 6.2 The �intelligent� nonwovens � The new applications................................................ 207 6.2.1 Biodegradable nonwovens.......................................................................................... 207 6.2.2 Medical nonwovens.................................................................................................... 212 6.2.3 Nonwovens against electromagnetic pollution........................................................... 219 6.2.4 Protection against radiations....................................................................................... 221 6.2.5 Nonwovens with thermoregulating properties ........................................................... 222 6.2.6 Tridimensional textiles ............................................................................................... 222 Multilingual dictionary .......................................................................................224