Handbook of Nonwovens

S. J. Russell

• Publisher: Woodhead Publishing
• Year: 2006
• eBook ISBN: 9781845691998
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Nonwovens are a unique class of textile material formed from fibres that are bonded together through various means to form a coherent structure. Given their rapid industrial development and diverse markets, understanding and developing nonwovens is becoming increasingly important. With its distinguished editor and array of international contributors, the Handbook of nonwovens, offers a comprehensive review of the latest advances in this area and how they can be applied to particular products.Initial chapters review the development of the industry and the different classes of nonwoven material. The book then discusses methods of manufacture such as dry-laid, wet-laid and polymer-laid web formation. Other techniques analysed include mechanical, thermal and chemical bonding as well as chemical and mechanical finishing systems. The book concludes by assessing the characterisation, testing and modelling of nonwoven materials.Handbook of nonwovens is a valuable reference for those involved in the manufacturing and use of nonwoven products in such areas as; transport, medicine, hygiene and various branches of engineering. - Provides a comprehensive review of the latest advances in this important area - Written by leading experts in the field - Discusses different methods of manufacture, bonding and finishing

1

Development of the nonwovens industry

A. Wilson Nonwovens Report International, UK

1.1 Definition and classification

In defining what a nonwoven is, there is always at least one exception that breaks the rule. This is perhaps fitting, since while being now recognised in its own right, the nonwovens industry has drawn on the practices and knowhow of many other more well-established fields of polymer and materials manufacturing with a piratical disregard and an eye to the most diverse range of end-use products. For this reason, it is possible for companies with almost nothing in common, with vastly different structures, raw materials and technologies, areas of research and development and finally, customers to be grouped together under the nonwovens ‘umbrella’. Many would define themselves by the customers they serve, as being in the medical, automotive, hygiene or civil engineering industries, for example.

The term ‘nonwoven’ arises from more than half a century ago when nonwovens were often regarded as low-price substitutes for traditional textiles and were generally made from drylaid carded webs using converted textile processing machinery. The yarn spinning stage is omitted in the nonwoven processing of staple fibres, while bonding (consolidation) of the web by various methods, chemical, mechanical or thermal, replaces the weaving (or knitting) of yarns in traditional textiles. However, even in the early days of the industry, the process of stitchbonding, which originated in Eastern Europe in the 1950s, employed both layered and consolidating yarns, and the parallel developments in the paper and synthetic polymer fields, which have been crucial in shaping today’s multi-billion dollar nonwovens industry, had only tenuous links with textiles in the first place. Therefore, the nonwoven industry as we know it today has grown from developments in the textile, paper and polymer processing industries. Today, there are also inputs from other industries including most branches of engineering as well as the natural sciences.

Certainly today, the nonwovens industry is reluctant to be associated with the conventional textile industry and its commodity associations nor would it want its products to be called ‘nonpapers’ or ‘nonplastics’. The term ‘nonwoven’, then, which describes something that a product is not, as opposed to what it actually is, has never accurately represented its industry, but any attempts to replace it over the years have floundered. The illusion created by this misnomer has been for some to think of nonwovens as some kind of bulk commodity, even cheap trade goods, when the opposite is often true. The nonwovens industry is highly profitable and very sophisticated, with healthy annual growth rates in double digits in certain sectors and parts of the world. It is perhaps one of the most intensive industries in terms of its investment in new technology, and also in research and development.

EDANA, (The European Disposables and Nonwovens Association) defines a nonwoven as ‘a manufactured sheet, web or batt of directionally or randomly orientated fibres, bonded by friction, and/or cohesion and/or adhesion’, but goes on to exclude a number of materials from the definition, including paper, products which are woven, knitted, tufted or stitchbonded (incorporating binding yarns or filaments), or felted by wet-milling, whether or not additionally needled. To distinguish wetlaid nonwovens from wetlaid paper materials, the following differentiation is made, ‘more than 50% by mass of its fibrous content is made up of fibres (excluding chemically digested vegetable fibres) with a length to diameter ratio greater than 300’. Other types of fabric can be classified as nonwoven if, ‘more than 30% by mass of its fibrous content is made up of fibres (excluding chemically digested vegetable fibres) with a length to diameter ratio greater than 300 and its density is less than 0.40g/m³. This definition, which forms ISO 9092:1988 and EN 29092, was most likely coined prior to the enhancement of plastic film layers which have become broadly indistinguishable from fabrics in modern multi-component or composite nonwovens.

INDA, North America’s Association of the Nonwoven Fabrics Industry, describes nonwoven fabrics as ‘sheet or web structures bonded together by entangling fibres or filaments, by various mechanical, thermal and/or chemical processes. These are made directly from separate fibres or from molten plastic or plastic film.’ Nonwovens are engineered fabrics that can form products that are disposable, for single or short-term use or durable, with a long life, depending on the application. In practice, the life of a nonwoven product can be measured in seconds, minutes, hours or years but the design and engineering requirements of these fabrics are often complex and challenging regardless of the intended product life (Table 1.1).

Table 1.1

Examples of nonwoven product applications

Hygiene	Wipes	Medical and surgical	Protective clothing	Filtration (gas and liquids)	Interlinings and garments	Shoes, leather-goods and coating substrates	Upholstery...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright page
• Contributor contact details
• 1: Development of the nonwovens industry
• 2: Dry-laid web formation
• 3: Wet-laid web formation
• 4: Polymer-laid web formation
• 5: Mechanical bonding
• 6: Thermal bonding
• 7: Chemical bonding
• 8: Nonwoven fabric finishing
• 9: Characterisation, testing and modelling of nonwoven fabrics
• Index