THE SPUNBONDED AND MELT BLOWN TECHNOLOGY HANDBOOK

Transcription

1 THE SPUNBONDED AND MELT BLOWN TECHNOLOGY HANDBOOK Prepared by: Ian Butler International Nonwovens Consulting, Inc.

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3 TABLE OF CONTENTS Part 1. Spunbonded Technology Introduction to Spunbonded Materials... 1 History of the Spunbonded Technology... 2 Markets... 3 Worldwide Growth... 3 Growth By Region... 3 Share of World Nonwoven Production... 4 Resins... 6 Influencing Physical Properties... 6 Resin Types... 6 Some Physical Properties of Resins... 7 Principal End Markets of the Various Resins... 9 Polypropylene... 9 Polyester High Density Polyethylene Nylon & Other Success Stories Cover stock Home Furnishings and Bedding Medical and Surgical Disposables Automotive Other Developments Process Technologies...? Circular, Curtain Spinning Spunbonded/Melt Blown Composites... 20

4 Part 2. Melt Blown Technology Introduction to Melt Blown Materials... 1 History of the Melt Blown Technology... 2 Markets... 3 Worldwide Growth... 3 Growth By Region... 3 Share of World Nonwoven Production... 4 Resins Used... 5 Selected Physical Properties of Resins... 6 Major Markets... 7 Monolithic... 7 Composites/Laminates... 8 Success Stories... 9 Cover stock... 9 Medical Air Filtration Sorbents Liquid Filtration Other Developments Technology Glossary of Terms for Spunbonded and Melt Blown Technologies... 15

5 INTRODUCTION The melt spinning process is the most efficient method to produce a fabric. Melt spinning is an extrusion process which uses molten polymer resins and produces fabrics from the fibers as the same time. This handbook describes the markets and technologies of the two melt spinning processes, commonly referred to as spunbonded and melt blown. The technologies are covered separately in this handbook because the fiber spinning technologies are quite different and the resulting fabrics have distinct physical properties. Although the fabrics are produced by the same principle, there is little inter-process competition in the market. It is rare to see spunbonded and melt blown materials compete headto-head. In fact, the reverse is the case. Both technologies produce nonwoven materials with physical characteristics that often complement each other and the markets for spunbonded/melt blown composites have developed rapidly around the world. The spunbonded technology, developed only in the mid 1960 s, has emerged as the most important nonwoven technology as it accounts for about half of the North American and European nonwovens output. The spunbonded technology has a number of advantages, not the least being the fabric s durability and lower cost in comparison to other nonwovens and conventional woven and knitted fabrics. Spunbonded fabrics are found in many disposable markets, such as diapers, sanitary napkins and medical. Important durable end markets include bedding and home furnishings, agriculture, carpeting and house construction. Melt blown fabrics are made from fibers that are much finer than those extruded in the spunbonded process. The fibers fineness produces fabrics that are softer but much weaker than spunbonded materials. Due to the larger volume of fibers per given weight, melt blown materials have improved fiber distribution and high coverage per unit weight. The resulting characteristics are important to a broad range of product applications. For example, melt blown fabrics have good barrier properties and high insulating values and thus are used widely in filtration, barrier materials for medical and disposable apparel and apparel insulation. The melt blown technology is flexible and many unique composites with various fibers and other materials have been developed. A notable success is a wood pulp/melt blown composite which is used in premoistened baby wipes as well as industrial wiping applications.

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7 Part 1: THE SPUNBONDED TECHNOLOGY HANDBOOK

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9 INTRODUCTION TO SPUNBONDED MATERIALS DEFINITION Spunbonded materials are nonwoven textiles made by a process in which the nonwoven web is made as the fibers are being formed from a molten resin. It is an integrated one step nonwoven process beginning with a polymer resin and finishing with a finished fabric. Any polymers that can be worked in the spinning process are usable. Resins most often spunbonded include polyolefins (polypropylene and polyethylene), polyester, polyamides 6 and 66 (nylon) and bicomponents. Small volumes of miscellaneous resins are spunbonded for specialty markets. SPUNBONDED PROCESS In the conventional production of spunbonded materials, a polymer is heated until the viscosity is right for extruding the material into filaments through a

10 spinning process. Air is introduced to cool the stream of molten filaments and at the same time draw the filaments to the specified diameter. The cooled loose filaments are deposited onto a moving conveyor and transported to a bonding device. The web of loose filaments may be thermally bonded using heat and pressure, mechanically bonded by needle punching or chemically by using some bonding agent. The integrated technology of producing fiber and textile in one process is the most economical method of making a fabric.

11 HISTORY OF THE SPUNBONDED TECHNOLOGY The spunbonded technology was developed in the mid 1960 s by Lurgi, a German engineering firm. The system, licenced by Lurgi to producers, was primarily conceptual and required considerable research and development by the licensees to bring the process to commercialization. The early spunbonded systems were large, expensive and required a large amount of energy to operate. Because of the high capital costs and associated technical risks, only a few larger companies had the resources to develop the technology. The spunbonded fabrics from these early production lines were poor in relation to the carded web technology, which was the dominant technology at the time. Aesthetically, the web was inconsistent with knotted fibers. Spunbonded s competitive advantage was the fabric s superior strength and low cost over other nonwoven materials because of the efficiency of producing the fabric directly from a polymer resin. Production from these early lines was generally directed towards replacing more costly and heavier woven, knitted or other nonwoven materials. With time, these missionary spunbonded producers advanced the technology with improvements to fabric uniformity, softness and strength. Eventually, lightweight spunbonded materials were developed for use in such demanding applications as cover stock and medical products. However, in spite of this progress, few nonwoven producers expanded into the spunbonded technology, apprehensive of the technical and financial risks. This changed in the early 1980 s as several European machinery manufacturers developed commercial, turn-key spunbonded systems. Spunbonded materials from these systems were crude by today s standards. By the end of the decade these machinery manufacturers had refined their technologies and introduced multi-beam systems which could produce high quality spunbonded materials over a wide range of weights. Within a few years, spunbonded/melt blown composite lines were available from these machinery producers to target the cover stock and medical markets. The availability of the commercial spunbonded systems resulted in a rapid growth of the technology worldwide. From a global perspective, spunbonded has grown to be the dominant nonwoven technology and is amongst the fastest growing nonwoven technologies. The combination of lower manufacturing costs and products with superior strength and good web uniformity relative to alternatives provides this technology with a significant competitive edge in many markets.

12 MARKETS WORLDWIDE GROWTH Spunbonded materials and spunbonded/melt blown composites are produced in many nations around the world. Over the past decade, volume has increased almost 9% per year and annual worldwide production will approach 5 billion pounds (2.3 million tonnes) by the end of the first decade. Worldwide Spunbonded Growth (billions of pounds) Source: International Nonwovens Consulting, Inc. GROWTH BY REGION The largest producing regions of spunbonded materials are North America, Europe and Japan. Together these regions produce and consume about 80% of the world s spunbonded materials.the rapid growth which occurred in these areas for a number of years has moderated somewhat as spunbonded materials attained high penetration of their markets. Spunbonded s expansion

13 in the emerging markets is expected to maintain this technology s growth rate for many years. The emerging market s volume is increasing about 15% per year. At the end of the century emerging markets were about 20% of the world s consumption and a rise from slightly less than 10% a decade earlier. The increasing demand by absorbent (cover stock), disposable medical, home furnishing and bedding industries in these markets is driving spunbonded material s growth. The growth rates vary by region, depending upon the level of development of the nonwoven industry in the various countries. The emerging markets include Mexico, South America, China, Southern Africa, India and other Pacific Rim. By far, most spunbonded materials produced in these markets are made from polypropylene resin. The spunbonded markets in emerging markets are forecast to represent 30-35% of worldwide demand by Spunbonded Production by Region (millions of pounds) Japan Rest of World Europe North America TOTAL Source: International Nonwovens Consulting, Inc.

14 SHARE OF WORLD NONWOVEN PRODUCTION Early in the new century, spunbonded and spunbonded/melt blown composites nonwovens will account for over 40% of total nonwoven production around the world. This is a rise from less than 20% of the world s nonwoven output in the early 1980 s. Spunbonded materials are increasing their share because of their favourable pricing and strength/mass ratio in comparison to alternate nonwovens and woven materials. Spunbonded and spunbonded/melt blown polypropylene composites have a significant share of the cover stock market, the largest single nonwoven market. The growing consumption of cover stock in emerging markets around the world is one of the major factors driving the spunbonded technology s growth. Share of Total Nonwoven Market (% share - pounds) Source: International Nonwovens Consulting, Inc.

15 PHYSICAL PROPERTIES INFLUENCING PHYSICAL PROPERTIES There are many factors which influence the physical and aesthetic properties of a spunbonded material. Among the major variables that affects the physical properties of a spunbonded web are: type of resin or polymer used filament variables; thickness or diameter, crimp, fiber cross section, filament drawing system bonding method; needlepunched, degree of point bonding or addition of a bonding resin or binder fibers web properties; fiber orientation, web uniformity Some of the key variables are discussed in the following several pages. RESIN TYPES The choice of a polymer has a significant influence on the physical and chemical properties of a spunbonded fabric. Several resins are used to produce spunbonded materials. Polypropylene is the dominant resin accounting for two thirds of total spunbonded output. Polypropylene is also the fastest growing because of its wide acceptance in several applications, such as absorbent products cover stock, medical and several durable end markets which are growing faster than the industry. Worldwide growth of spunbonded polypropylene has averaged about 12% per year which is expected to continue for the foreseeable future. Polyester and polyester bicomponents are the second most important resins with about a quarter of spunbonded production. The growth of polyester spunbonded production has been lower than polypropylene as most of these material s are sold to durable end markets where polyester has already captured a significant market share. The consumption of spunbonded polyester and polyester bicomponents are expected to rise about 6% annually over the next several years. The production of high density polyethylene (HDPE) is limited to only two manufacturers: DuPont and Asahi. Most output is sold to durable markets. Nylon, totalling less than 2% of the world s spunbonded output is consumed in various

16 end markets where exceptional strength or chemical resistance is required. Small amounts of spunbonded material made from other resins are produced on a few production lines around the world for specialty markets. Total annual production is a few million pounds per year. Resins Consumed by Spunbonded Processes (pounds) High Density Polyethylene Polypropylene Nylon & Other Polyester Source: International Nonwovens Consulting, Inc. SELECTED PHYSICAL PROPERTIES OF RESINS The following table provides the typical physical properties from spunbonded materials made from the various resins. High Density Polypropylene Polyester Polyethylene Nylon Melting Point (ºC) Specific Gravity Aesthetics Soft Crisp Soft, Slick Crisp Abrasion resistance Very good Very good Low High Crease recovery Moderate High Low High Source: International Nonwovens Consulting, Inc.

17 FILAMENT VARIABLES Filament denier (thickness), crimp and cross section also influence the physical properties of the spunbonded web although it is produced from the same resin. Coarse denier (10-15 denier) spunbonded fabrics are often stiff and rough feeling and are generally produced for durable end markets. In contrast, spunbonded web of fine denier (1.5-3 denier) filaments will have higher web uniformity, softer hand and draping qualities. Most fine denier spunbonded fabrics are found in consumer and disposable products, such as cover stock, fabric softener substrate and apparel items. Fibers that are crimped in the process yield a softer, more flexible finished web. Few producers crimp fibers in their spunbonded system. BONDING VARIABLES Point bond calendaring is the most common method for bonding spunbonded webs. The web s filaments are fused by heat and pressure at all points where the calendar meets the web. The ratio of the bonded area to the unbonded area affects many of the web s physical properties, i.e., strength, tear resistance, softness, abrasion resistance and others. For example: the higher the ratio, the stiffer the finished fabric. Needle punching a spunbonded web yields a higher strength fabric which resists distortion. Some manufacturers add a resin bonding agent in a post manufacturing operation to improve filament adhesion and increase their web s strength or gain other desirable properties. In all cases, it is important that the web is uniform with an even distribution of fibers. WEB PROPERTIES The distribution of individual filaments in a finished web is critical to the physical and performance characteristics of spunbonded materials. Unequal filament distribution, bundled or married fibers and filament separation are factors that will negatively affect a spunbonded fabric s performance and aesthetic qualities.

18 PRINCIPAL END MARKETS OF THE VARIOUS RESINS The physical and chemical attributes of a resin serving one market may be unacceptable in another market. For example, polypropylene has a low melting point and cannot be used in end products, such as molded carpet backing, where moderate heat is involved. The result is that there is only limited inter-resin competition and market overlap as illustrated below. Market Overlap of Resins Polypropylene Other Polyester High Density Polyethylene and Nylon Source: International Nonwovens Consulting, Inc. POLYPROPYLENE Polypropylene is a low cost, versatile resin with chemical and physical properties acceptable to many end products. Polypropylene s low specific gravity provides a higher fabric yield than any other fiber. It is attractive to spunbonded producers as it is less technically challenging to produce than spunbonded fabrics from other resins. Spunbonded materials made of fine denier filaments are used for end products which include cover stock, medical products (surgical gowns, surgical drapes, caps, masks, CSR wrap, shoe covers, staff and patient apparel), industrial apparel and several durable nonwoven markets. On a global basis, about two thirds of all fine denier spunbonded polypropylene is consumed by the absorbent (cover stock) and medical products markets. Coarse denier

19 spunbonded polypropylene is used in geotextiles, land scape, house wrap, carpet backing and several bedding and home furnishings markets. Some markets, such as land scape and home furnishings, are served by both coarse and fine denier spunbonded fabrics. Spunbonded and Spunbonded/Melt Blown Polypropylene by End-use (pounds) Carpet Components Agricultural/Landscape Geotextile Industrial Apparel Home Furnishings and Beddings Tarps & Other Cover Stock Medical Source: International Nonwovens Consulting, Inc. POLYESTER Polyester spunbonded materials have higher strength, relative to spunbonded polypropylene. It is more energy intensive than polypropylene because of its higher melting point. Spunbonded polyester s higher melting point and moldable properties makes this material attractive to carpet backing, roofing substrate and certain filtration end uses where heat is involved. Polyester is insensitive to many acids, salts and other corrosive materials. Several manufacturers produce spunbonded fabrics from bicomponent fibers. Bicomponent fibers are used to combine the strong attributes of each polymer or improve the web s strength. In the spunbonded process, bicomponent fibers generally have a polyester core with an outer sheath of some other polymer. The sheath is a lower melting point resin, generally nylon 6 or polyethylene. The web is bonded by calendaring or heating to soften the sheath which fuses the web s filaments at the cross-over points. Spunbonded webs using a polyester/ nylon 6 bicomponent are isotropic, moldable and have excellent dimensional

20 stability. Spunbonded with a polyethylene sheath are soft and drapable and resistant to many acids and alkalies. Spunbonded Polyester by End-use (pounds) Other Filtration Roofing Fabric Softener Carpet Backing Furniture and Bedding Source: International Nonwovens Consulting, Inc. HIGH DENSITY POLYETHYLENE High Density Polyethylene (HDPE) spunbonded materials are produced on a unique spunbonded process. The HDPE resin is dissolved in a solvent, extruded and the solvent is rapidly evaporated to filabrate the fibers. The heavily calendared web yields a lightweight, strong, semi impervious, tear and puncture resistant material. Its these properties that make this material particularly suitable for disposable industrial protective apparel. Other major markets are house wrap and durable papers (promotional banners, courier packs, labels, maps, tags). NYLON (Polyamide 6 or 6.6) A small percentage of total spunbonded nonwovens are made from nylon resins. The advantage of these resins is exceptional strength and resistance to damage from oils and many solvents such as acetones and alcohols. Major end markets are filtration, carpeting components, coating/laminated substrates and home furnishings

21 OTHER RESINS Small volumes of spunbonded materials made from cuprammonium rayon. Major markets are medical gauze, wipes, clean room applications, tea bags and seed tapes. Spunbonded carbon is used primarily in filtration applications. The fine filaments have in total a large surface area and absorb gases and other contaminants faster than conventional absorbent materials, such as activated charcoal.

22 SUCCESS STORIES COVER STOCK Disposable baby diapers, sanitary napkins, adult incontinence products, training pants and underpads are referred to as absorbent products. These products use cover stock in their construction, most of which is from nonwoven fabrics. Cover stock is a generic term which refers to top sheet, barrier leg cuff, back sheet, acquisition/transfer layers and stretchy panels. Cover stock is the largest market for nonwoven fabrics. It accounts for a quarter to a third of total nonwoven consumption in most developed or emerging markets. Up until the early 1990 s most cover stock in North America, Europe and Japan was made from thermal bonded polypropylene fibers. The use of spunbonded polypropylene materials expanded rapidly as turn-key, commercial lines were installed by nonwoven producers. Today, spunbonded materials are used widely as top sheet. In the mid 1990 s, diaper producers introduced spunbonded/melt blown/spunbonded composites (SMS) in their barrier leg cuffs replacing thermal banded materials. A market is developing for putting lightweight SMS materials on the exterior layer of baby diapers and adult incontinent pads to provide a textile-like, soft hand to the product.

23 SUCCESS STORIES HOME FURNISHINGS AND BEDDING Upholstered furniture and bedding construction materials are major markets for nonwoven fabrics. Spunbonded nonwoven fabrics have replaced traditional textiles in many home furnishing and bedding applications and have achieved high penetration in many components. Upholstered furniture construction end uses which consume spunbonded material includes dust covers, upholstery reinforcement, spring insulators, decking and breather fabrics. Bedding construction consumes spunbonded fabrics in flanging, quilt backing, spring insulators, and dust covers. Most furniture and bedding spunbonded construction fabrics are made from polypropylene but some quantities of polyester and nylon materials are also applied. Coarse and fine denier spunbonded materials are consumed by these markets. Spunbonded nonwovens are also used in other home furnishing products, such as quilt backing, mattress toppers, pillow inserts, window shades and blinds.

24 SUCCESS STORIES MEDICAL AND SURGICAL DISPOSABLE PRODUCTS The health care industry employs several types of nonwoven materials in limited use items and disposable apparel. Nonwovens offer good value in protecting medical personnel and patients from the spread of infectious diseases transmitted by blood or other body fluids. Spunbonded and spunbonded/melt blown composites have captured a significant share of the disposable limited use and surgical apparel markets. Spunbonded fabrics are used in surgical apparel, surgical drapes, caps, masks, shoe covers, patient gowns, staff apparel and sterilization wrap. In the U.S., spunbonded and SMS are the second largest volume fabrics consumed in medical end products accounting for about a third of total nonwoven usage.

25 SUCCESS STORIES AUTOMOTIVE Spunbonded nonwoven fabrics are used widely in automotive interior end uses. The automotive market is one of the more important markets for spunbonded materials. The largest end use is automotive carpet backing. The auto industry commenced to replace natural jute carpet backing with spunbonded polyester and woven polypropylene backing in the early 1980 s. About 60% of carpet backing now employs spunbonded polyester backing. Spunbonded polyester s advantage is its notable property of strength and pliability with heat which allows producers the ability to draw and mold tufted carpeting into complex flooring shapes. Spunbonded polyester is also used to impart moldability to needlepunched interior soft trim. These applications include trunk liners, rear package shelves, door trim, map pockets, seat trim and several other applications. Polyester based spunbonded materials are also used in other automotive areas which include filtration, dashboard insulators, pull strips, seating and reinforcement backing.

26 SUCCESS STORIES OTHER DEVELOPMENTS House Wrap Various materials are replacing the traditional black asphalt construction paper placed under the final exterior cladding. Spunbonded HDPE and spunbonded polypropylene with a coated finish have captured the largest share of the house wrap market in North America and Europe due to their durability and performance. Spunbonded s micro porous nature allows moisture vapours to escape preventing the build up of damaging moisture within the exterior walls, but at the same time providing resistance to wind and water penetration. These materials make a house more air tight and reduce heating and air conditioning costs. Roofing The roofing industry is an increasingly important market for spunbonded polyester. The major end market is a reinforcement substrate material used in producing modified bitumen roofing. Modified bitumen roofing, a relatively new roofing innovation, has captured about a quarter of the North American commercial installations, but has a much higher share in Europe. While other substrates are used, spunbonded polyester is a major factor because of its strength when heated during the production process. Spunbonded polyester materials are also used in roofing repairs and occasionally in traditional builtup roofing (BUR) systems. Durable Papers Spunbonded nonwovens made from HDPE have achieved success in several products that usually are made of paper. The HDPE materials are printable, light weight, puncture resistance and have good tear strength, even when wet. Durable paper made of HDPE have captured a large share of the security envelopes and courier packs business. The material is also used in maps, banners and billboard displays.

27 PROCESS TECHNOLOGIES The spunbonded process produces nonwoven textiles integrated with the making of the fibers. Four steps are involved: spinning the filaments, drawing and cooling the filaments, laying the filaments into an even web and bonding the web. Below is a simplified drawing of the spunbonded process. Spunbonded Line Resin Extruder Spun Pump Spinning Head Cooled Quench Air High Pressure Air Drawing Molten Resin Suction Air Bonding Calendars Wind Up FInished Product 6 Source: International Nonwovens Consulting, Inc.

28 CIRCULAR SPINNING (LURGI-DOCAN) The first spunbonded process was the Lurgi-Docan system. The filaments are produced in circular bunches from round nozzles mounted in a series across the web. Various methods, such as static electricity, deflector plates and air currents are employed to separate the filaments prior to lay down on the moving screen to produce a homogeneous web structure. Circular Spinning Molten Resin Input Spinnerettes Filaments Source: International Nonwovens Consulting, Inc. CURTAIN SPINNING Curtain spinning is a development which followed the Lurgi-Docan process. The filaments are formed in a single, uniform spinning die which extend across the web. An advantage of this system is improved web uniformity and its avoids the bunching and filament separation issues. Curtain Spinning Molten Resin Input Filaments Spinnerette Source: International Nonwovens Consulting, Inc.

29 SPUNBONDED/MELT BLOWN COMPOSITES (Multi-Denier Spinning) Spunbonded/melt blown composite spunbonded materials are attractive as they combine the physical properties of spunbonded and melt blown materials into one nonwoven web. The melt blown process is similar to the spunbonded technology but produces a much finer denier filament and webs of excellent uniformity. As melt blown webs have low strength, the web layer is sandwiched between higher strength spunbonded materials. This light layer of melt blown fiber improve the composite s uniformity at low weights. The composite fabric is hydrophobic and is used widely as barrier leg cuffs and diaper back sheets. Multi-denier spunbonded materials are generally made by integrating the spunbonded and melt blown nonwoven processes into one unit. A small volume of multi-denier fabrics are also produced off line by laminating separate spunbonded and melt blown webs. The multi-denier process can have many configurations, i.e spunbonded/ melt blown (SM); SMS, SMMS, SMSMS, SSMS. Virtually all multi-denier spinning is made with polypropylene resins. SMS Nonwoven Line Spinbonding Machine Melt Blown Machine Spinbonding Machine Winder Filament drawing unit Screened conveyor belt Bonding calender Layer distribution Source: International Nonwovens Consulting, Inc.

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31 Part 2: THE MELT BLOWN TECHNOLOGY HANDBOOK Prepared by: Ian Butler International Nonwovens Consulting, Inc. Edited by: Edward Vaughn, PhD, Clemson University Larry Wadsworth, PhD, Universith of Tennesee

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33 INTRODUCTION TO MELT BLOWN MATERIALS Photo (??? Melt Blown Production Line???) DEFINITION Melt blown materials are nonwoven textiles made by a process in which the web is made as the fibers are being formed from a molten resin. It is an integrated, one step nonwoven process beginning with a polymer resin and ending with a finished, self bonded fabric. The process is similar to the spunbonded process, but melt blown filaments are much finer. MELT BLOWN PROCESS A typical melt blown process heats a polymer to the point where the molten material can be extruded through a spinning die. Streams of high velocity, heated air is injected near the die tip and attenuates (pulls and stretches) the filaments to finer diameters. The filaments are quenched with cool air and then blown

34 and collected on a moving collector screen. The filaments from a commercial production line are generally in the 2-5 micron range but the technology can produce fibers from less than 1 micron to more than 100 microns in diameter. Because of the extremely fine filaments, the resulting fabric is generally soft and drapable with excellent uniformity at low weights. This versatile technology can produce melt blown webs from any thermoplastic resin, including adhesives, which have a viscosity low enough to extrude through the spinning die.

35 HISTORY OF THE MELT BLOWN TECHNOLOGY The melt blown technology was first demonstrated in the mid-1950 s by the Naval Research Laboratories which was intent on developing extremely fine denier fiber for use in high altitude atmospheric research. Conceptually, this process was similar to a 1940 s Owens-Corning development of producing micro denier fiberglass. In the Owens-Corning process, glass fibers of 1 mm diameter were drawn by a jet flame to diameters of 0.5 micron. In the mid 1960 s, Exxon was doing considerable research to find significant end uses for their recently commercialized polyolefin resins polypropylene and polyethylene. Exxon was attracted to the fine denier, technological work done at Naval Research Laboratories and invested in a narrow demonstrator line. The promising results from this line led Exxon to invest further into this new melt blowing technology and by 1970 the company had a triple, extrusion beam development line in operation. The line was semi-commercial but used primarily by Exxon to further research and develop the melt blown technology. It was Exxon s decision not to commercialize the technology, but instead license the process to other companies. One of the earlier successful commercial lines was built by Tonen Tapyrus, an affiliate of Exxon located in Japan, which had a commercial line operating in Early licensees were Kimberly-Clark, 3M, Johnson & Johnson, Web Dynamics, Ergon and James River. Exxon concentrated on further technology developments and production of the special resins for the new technology. Commercially acceptable melt blown material require a production line built to exacting tolerances. To assist licensees, Exxon licensed the manufacturing of the commercial melt blown lines to Accurate Products in the U.S. and Reifenhauser in Germany after the companies demonstrated they had the capabilities to manufacture and market commercial melt blown lines. The average melt blown line produces filaments in the 2-5 micron range. The web s uniformity and micro porous nature makes this technology attractive to many end products. Melt blown fabrics first significant commercial successes were monolithic filtration media, sorbents and battery separator materials. There has been considerable success with melt blown laminates and composites. Kimberly-Clark, an early licencee, contributed many innovations to the technology with their development of the spunbonded/melt blown and other melt blown composite technologies.

36 MARKETS WORLDWIDE GROWTH Melt blown nonwovens had exceptional growth rates during the period of increasing on average about 14% per year over the decade. Volume by the middle of the past decade is expected to reach about 400 million pounds, almost triple the volume from the mid 1990 s. The major factor driving this growth has been the rapid demand for spunbonded/melt blown composites used in absorbent hygiene products, such as baby and adult diapers and medical markets. Worldwide Melt Blown Growth (millions of pounds) Source: International Nonwovens Consulting, Inc. GROWTH BY REGION The major developed markets, North America, Europe and Japan account for about 80% of the world s melt blown production. Volume in the emerging markets is increasing rapidly and is expected to almost double between 1998

37 and The main factor driving this increase in the emerging markets to increasing consumption of absorbent hygiene products using spunbonded/melt blown cover stock fabrics. Melt Blown Production by Region (millions of pounds) Japan Rest of World Europe North America TOTAL Source: International Nonwovens Consulting, Inc. SHARE OF WORLD NONWOVEN PRODUCTION In 1998, melt blown nonwovens represented about 3% of the world s nonwoven output. The technology s share rose to almost 7% by 1998 and will exceed 8% by The increasing use of spunbonded/melt blown polypropylene composites in cover stock and medical applications is the principal driver of this growth. A major factor will be the expected growth of baby diapers and adult incontinent in emerging nonwoven markets around the world. Emerging nonwoven

38 markets, such as China, Brazil, Argentina, Mexico have installed state-of-theart spunbonded/melt blown lines to meet their cover stock requirements. Melt Blown Share of World Nonwoven Production (% share - pounds) Source: International Nonwovens Consulting, Inc. RESINS USED The choice of polymer has a major influence on the physical and chemical properties of melt blown materials. Several resins are used to produce melt blown materials. Polypropylene currently accounts for an estimated 95-97% of all melt blown production. Polypropylene has gained such a dominant position because it is relatively inexpensive, easy to melt blow, bonds readily and is fairly inert. Small amounts of polyester, nylon and more exotic resins are used generally for special filter applications where heat or corrosive elements are present. For example, the use of E-CTFE Halar resin is leading to applications in high temperature filtration. The Kraton elastomeric resin is melt blown into in elastic web which is joined

39 to other materials, generally nonwovens, to make stretchy fabrics used in absorbent hygiene products and home furnishing applications. Resins Used (% share - pounds) All Other Polyester Polypropylene Source: International Nonwovens Consulting, Inc. SELECTED PHYSICAL PROPERTIES OF RESINS The following table provides some typical properties of melt blown nonwovens made from various resins. 6.6 Polypropylene Polyester Nylon Melting Point (ºC) Specific Gravity Aesthetics of Web Soft Crisp Crisp Relative Resin Cost lowest higher highest Ease to Melt Blow easy difficult very difficult Bonding Ease excellent good good Resistance to Solvents, Acids, Alkalies excellent good very good

40 MAJOR MARKETS MONOLITHIC AND OMPOSITES/ LAMINATES Monolithic melt blown are materials that are uncombined or unsupported by another fabric. Composite melt blown refers to melt blown materials which have another material, such as a nonwoven material or woven scrim, added to the melt blown web to add strength and/or stability. Melt blown composites also include material produced with wood pulp and fibers added to achieve special properties. Composite melt blown accounted for about a third of total melt blown consumption in Early in the new century about two thirds of melt blown materials will be in composite form. Melt Blown Share of World Nonwoven Production (% share - pounds) Source: International Nonwovens Consulting, Inc.

41 Monolithic The combined markets of North America and Europe consume about 70 million pounds of monolithic melt blown materials. Monolithic materials in these two regions represent about a third of the total melt blown production. The largest markets oil sorbents and filtration which account for more than 80% of the monolithic market. The many small pores and hydrophobic nature of polypropylene makes melt blown polypropylene a leading filter material. Major Monolithic Melt Blown Markets in North America and Europe (pounds) Wipes Other Oil Sorbents Liquid Filtration Hygiene Air Filtration Source: International Nonwovens Consulting, Inc. Composites/Laminates About two thirds of all melt blown materials are produced in a composite or laminated form. By far the largest volume of melt blown composite are spunbonded/melt blown materials used in disposable absorbent hygiene and medical products. Melt blown filaments are fine denier, and the webs have excellent uniformity but relatively low strength. To overcome the low tensile strength, the melt blown web is sandwiched between layers of higher strength spunbonded material. The resulting composite is a lightweight nonwoven material with good uniformity, strength and barrier properties. Kimberly-Clark developed a Coform, a melt blown composite technology which injects fluffed wood pulp into the stream of molten polypropylene polymer resulting in an intimate blend of both materials. The Coform material is a bulky,

42 absorbent material is used primarily in baby wipes and some panty liners. A similar technology in concept was developed by 3M. The 3M process adds crimped fibers to the melt blown web to add strength, stability and loft. The resulting material, referred to a Thinsulate, is a light weight insulation material used in outdoor apparel, sports wear and other products requiring insulation. Major Composite and Laminate Melt Blown Markets in North America and Europe (pounds) Other Hygiene Apparel Insulation Medical Air Filtration Source: International Nonwovens Consulting, Inc. Wipes

43 SUCCESS STORIES COVER STOCK Photo Disposable absorbent hygiene products, which include baby diapers, sanitary napkins, adult incontinence and training pants, use cover stock in their construction. Cover stock is a general term which refers to top sheet, barrier leg cuff, back sheet, acquisition/transfer layers and stretchy panels. Cover stock is the largest single market for nonwoven fabrics. Increasingly, absorbent hygiene producers are using cover stock made from melt blown composites materials in their products construction. Early in the 2000 s, the North American market will consume about150 million pounds of SMS nonwovens in absorbent products. World consumption will approach 400 million pounds. Lightweight SMS composites have mostly replaced heavier carded thermal bonded and plain spunbonded materials in the barrier leg cuff component of baby diapers. The SMS materials advantage is lower weight and superior barrier properties than the materials they replaced. The use of lightweight SMS materials in the back sheet layer of baby diapers and adult incontinence pads is growing rapidly. This SMS material provides a textile-like, soft hand to the product. Monolithic and melt blown composite materials are often found in the acquisition/transfer layer. Kimberly-Clark successfully incorporates stretchy side panels made from melt blown elastomeric resin in their disposable training pants and on some diapers.

44 SUCCESS STORIES MEDICAL Photo ( Surgery photo on CD) Health care systems consume several types of nonwoven materials in single or limited use items. End products include disposable surgical apparel and drapes, patient gowns and various other apparel items. Nonwoven surgical gowns and patient drapes are employed in about 75% of all surgical procedures in U.S. hospital operating rooms. Consumption of similar nonwoven items in the European market is lower, but growing. Single-use nonwovens offer superior barrier properties to bacteria, blood and other pathogens. They also reduce the potential of cross infection in comparison to the woven, reusable products they replace. Full cost studies have demonstrated that disposable surgical gowns, drapes and other apparel items are equivalent or lower in cost than laundering, sterilizing and maintaining reusables. Spunbonded/melt blown composites are used extensively in surgical apparel, surgical drapes, caps, masks, patient gowns, staff apparel and sterilization wrap. Monolithic melt blown materials are used as filter media in disposable face masks and small quantities are found some medical bandages.

45 SUCCESS STORIES AIR FILTRATION Photo ( Surgery mask on CD) Many types of nonwoven materials are used as air filtration media. Melt blown materials are ideal filtration media because their fine denier filaments and superior web uniformity are capable of capturing microscopic particles. About 150 million square yards of monolithic and composite melt blown materials are consumed in air filtration end uses worldwide. Significant end applications for melt blown media include disposable medical and industrial face masks, respirators, vacuum cleaner bags and HVAC installations. Melt blown volume continues to increase annually propelled by increasing filtration needs and gaining share over other filtration media. For example, melt blown media is steadily replacing micro-glass used in disposable face masks and HVAC installations. Its low cost and ease of handling by workers, versus micro-glass, are prime reasons for its growing acceptance in those filtration markets. Developing markets for melt blown air filter media are vacuum cleaner bags and automotive cabin air filtration. Melt blown media is added as a liner to vacuum cleaner bags to

46 filter fine dust particles not caught by the bag s paper media. At least half of all vacuum cleaner bags will use melt blown media by the turn of the century which is up from a few percent in the early 1990 s. Most European and Japanese built cars have cabin air filter systems. The use of melt blown media in automotive cabin filters is expected to grow rapidly as air filtration systems are included in North American new car and truck designs. The consumption of electret nonwoven filter media continues to expand in auto cabin, paint spray, and other air filtration end uses. This unique melt blown filter material maintains an electrostatic charge thereby improving the filter s efficiency.

47 SUCCESS STORIES SORBENTS Sorbent products are used in marine and industrial applications to clean up oil and chemical spills on water and land. The demand for sorbents has increased as legislators tighten environmental clean up laws and from the growing corporate concerns of employee injury in the workplace and the potential liability. Most sorbent materials are made from various absorbing materials such as ground corn cobs, clay granules, melt blown nonwovens and expanded glass. Melt blown materials have captured a major share of this expanding market. In fact, this is the largest single market for monolithic melt blown materials. Melt blown sorbent products are produced from polypropylene resin which has an affinity for oil. The attraction for oil is so strong that it will displace water already in the melt blown material. The existence of the myriad of micro-capillaries in the melt blown media increases the wicking and absorption of oil or other chemicals. Converted melt blown sorbent products include booms, mats, pillows and pads designed to meet various clean-up needs. In marine spills, large sausage-like booms filled with melt blown polypropylene are floated on the water to contain and absorb oil. In the work place, snakes (small booms), pads or blankets are placed around oily machinery to help create a safer work area for employees.

48 SUCCESS STORIES LIQUID FILTRATION Photo (???) Liquid filtration media is the second largest market for monolithic melt blown nonwovens. As with air filtration, the melt blown materials fine filaments and web uniformity are superior at trapping particles. Liquid filter applications vary widely and include chemicals, petrochemicals, blood products, pharmaceuticals, food and beverages, waste water, coolant water, cooking oils, and many more. Melt blown media is used in a wide assortment of depth cartridges, pleated cartridges and bag filters and have increased their share of these markets. Cartridge filters represent about half of the market for melt blown liquid filter media. Cartridge filters were initially produced by winding a string around a hollow inner core. Particles are trapped in the string windings as the contaminated liquids flows from the outside through to the core where the filtered liquid exits. Cartridges made with melt blown materials have the filament blown onto the core at varying densities and compression to improve filter efficiency. Melt blown cartridge filters have captured more than 50% of this market. Bag filters are

49 the second largest market for monolithic melt blow materials. Bag filters are used to filter large quantities of liquids, such as in water treatment plants or industrial waste water. Bag filters using melt blown materials are constructed with many layers of filter media and the melt blown materials used in the final layers. These multi layered bags are constructed to trap particles through all layers of the filter media. Most liquid melt blown filter media is produced from polypropylene resin as it has superior resistance to alkaline agents, mineral acids, organic acids and many solvents.

50 SUCCESS STORIES OTHER DEVELOPMENTS Wipes Wipes, made from nonwoven materials, have advantages over traditional rags, reusable towels and paper wipes. Nonwovens offer uniformity, cleanliness and dependable supply. Wipes, produced from monolithic and composite melt blown materials, are designed to meet the wiping requirements of specific institutional and industrial end markets. Melt blown wipes are lint free and used widely in clean room and other specialty areas where loose fibers could contaminate the work performed. Premoistened baby wipes made from a composite of melt blown polypropylene with wood pulp have a bulky and soft, cloth-like feel. This melt blown composite has captured about a third of the North American premoistened baby wipes market since its introduction in the early 1990 s. Insulation Soft and compressible insulation material for apparel is made from melt blown composites. These thin, flexible materials are used in accessories, such as gloves, which are difficult to insulate effectively without restricting movement. Considerable development work has led to the limited commercialization of melt blown insulation materials produced from recycled polyester pop bottles. The fine denier filaments are compacted into an insulation material with a superior insulation factor. The material s higher cost limits its use to specialty insulation applications, such as compact refrigerators or other small appliances.

51 TECHNOLOGY The melt blown technology produces nonwoven webs with fibers that are produced at the same time. It is a melt spin process similar in concept to the spunbonded technology. Three and possibly four steps are involved in the process: extruding the filaments; drawing and cooling the fibers with convergent heated and cooled compressed air; blowing the filaments onto a moving conveyor or take up screen and transported to windup. Bonding is the forth possible step as not all blown webs are calendar bonded. The melt blown technology can use any resin that have a relatively low viscosity when exiting the die. Most conventional melt blown processes use heated air to attenuate the filaments, but other fluids, such as steam, can be applied. Line art of: (??? line drawing of Melt Blown technology???) Source: International Nonwovens Consulting, Inc.

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53 GLOSSARY: Spunbonded and Melt Blown Technology Backing: A web or other material that supports and reinforces the back of a product, such a carpeting or wallpaper. Back sheet: The exterior surface of an absorbent hygiene product is generally made of film. The current trend is to improve the product s aesthetics by adding a nonwoven to cover the film. Barrier Leg Cuff: The raised cuff, which is a hydrophobic cover stock, used in a baby or adult diapers, designed to prevent leakage of body materials during use. Basis weight: The weight of a unit area of fabric. Examples are ounces per square yard and grams per square meter. Bicomponent fibers: Fibers made of two different polymers extruded into one filament (core within a sheath or side by side are examples). Binder: An adhesive, applied with a solvent or by melting a soften able plastic, to bond fibers together in a web or one web to another. Binder fiber: Fibers with lower softening points than other fibers in the web. Upon the application of heat and pressure, these act as an adhesive. Bond Strength: Amount of force needed to separate layers in a laminated structure or to break the fiber-to-fiber bonds in a nonwoven. Bursting Strength: The force needed to rupture a material. Calender: A machine used to bond sheets of fabric or film to each other or create surface features on these sheets. It consists of essentially two or more heavy cylinders that impart heat and/or pressure to the sheets that are passed between them. The rollers can be mirror-smooth, embossed with a pattern or porous. Calendering: A mechanical finishing process where a calender is used to laminate and to produce special surface features such as high luster, glazing and embossed patterns.

54 Carpet Backing: This is a support sheet on the back of a carpet through which the fiber are inserted or adhered. Primary backing is the principal material which holds the tufts. Secondary backing is occasionally applied on the underside of some backing to lock in the tufts and improve abrasion resistance, dimensional stability and strength. Clean room: An operating area in which airborne particles are controlled and the atmosphere is kept free of moisture, static, particles and ionic contaminants. Converter: An organization that takes nonwoven fabrics supplied in rolls and provides and an intermediate processing step, such as slitting, dyeing, coating, chemical finishes and printing. The fabric is then shipped to the finished products manufacturer. Cover stock: A lightweight nonwoven material used to contain and conceal an underlying core material. Examples are facing materials that cover the absorbent cores of diapers, sanitary napkins and adult incontinence products. The term cover stock now refers generally to facing material (top sheet), barrier leg cuff, back sheet, acquisition/transfer layer and stretchy panels. Crimp: The waviness of a fiber. Crimp amplitude is the height of the wave with reference to straight uncrimped fiber. Crimp frequency or level is the number of crimps per inch. Crimp energy is the work needed to straighten out a fiber. Crimp percent is the length difference between the crimped and stretched out fiber expressed as a percent. Cross Direction: The width dimension, within the plane of the fabric, that is perpendicular to the direction in which the fabric is being produced by the machine. Crystalline: Orderly arrangement of molecules and polymer chains in a fiber or plastic. Decitex (Dtex): One-tenth of a tex. A tex is equal to the weight in grams of 1 kilometer of a fiber. Denier: The measure of a weight per unit length of a fiber. Denier is numerically equal to the weight in grams of 9,000 meters of the material. Low numbers indicate fine fiber sizes and high numbers indicate coarse fibers. The tex system is used in countries outside the United States. A tex is numerically equal to the weight in grams on one kilometer of fiber. It can be calculated by dividing the denier by nine.