Personal Protective Equipment (PPE), the most common word in the current world as demand for PPE increased unprecedentedly during this COVID 19 pandemic situation.
PPE’s main goal is to reduce disease transmission so that PPE design should be allowed for intuitive but standardized doffing in a logical manner that minimizes the risk for self-contamination. Adaptive technology will enable health providers to deliver better and more intensive care and treatments to save lives.
PPEs–that includes mask, gloves, gown and so on—are used different Fabric of different safety level. E.g.;
- SMS Fabric for Biosafety Level -3 disposable gown
- Taffeta 210 Fabric for Biosafety Level -2 Reusable gown
- Knit and Woven Fabric (compact design & Chemical treated) for Level-1 isolation gown.
Among these 3 type of categories, SMS fabric is more important to ensure safety level 3. In the medical sector mainly used the PPE made by SMS fabric. The regular knit and woven fabric (with chemical treatment) cannot ensure Biosafety level 2. So once it requires the safety level 2 onward it must be Taffeta, SMS, or Nonwoven fabric.
An introduction of SMS fabric
Nonwoven materials have long been used for numerous applications such as in apparel, health care, engineering, for industrial purposes and for other consumer goods.
Spunbond-Meltblown-Spunbond (SMS) is one such material made of Polypropylene. The SMS fabric ensure the Medical Clothing’s range includes hospital gowns, medical caps, medical masks, and shoe covers which are manufactured using spunbond and meltblown techniques, as well SMS material where extra protection is appropriate, to suit all needs and preferences.
It is made up of a top layer of spunbond polypropylene, a middle layer of meltblown polypropylene and a bottom layer of spunbond polypropylene.
The spunbond process was first patented in 1940s and with further development has since become more and more popular across the world. The technique itself includes fibers being spun and then directly being dispersed into a web by deflectors or air streams. They use no chemicals, and are thermobonded. This technique is preferred as it is cost effective for manufacturers.
Over the past 20 years, it has been used to make several household products such baby diapers, adult diapers, medical products, protective apparel and hygiene products, but is also versatile enough to be used within construction, agriculture, and for coating. Spunbonds are also flame-retardant or have antistatic properties, and can therefore be used for increased ultraviolet and gamma ray protection. It has many features including: low weight, high strength, high air permeability, hydrophilic properties, and excellent wear and tear properties.
Furthermore, with the development of the technique, spunbonds are now much more soft and comfortable than previous types, and on average only weigh between 10 to 150 grams per square meter. As well as this, they can be printed, laminated, dyed, or electrostatically charged.
The meltblown process came after spunbond technology and is the process whereby ultrafine filament (micro-fibers) nonwovens can be produced at low costs. The technique includes hot air being blown onto molten thermoplastic resin that is extruded through a linear die containing hundreds of small holes, to form a fine fibered self-bonded nonwoven web. Its key feature is that it is an extremely thin fiber. As a result this material is often used for filters for air, liquids and particles, or as absorbents in products such as wipes, oil absorbents, incontinence products, and female hygiene, but can also be used in the production of certain electronics, adhesives, and other apparel.
Why does combine spunbond polypropylene with melt blown polypropylene create SMS?
As we know spunbond polypropylene has many excellent properties, strength and durability being just two of those. On the otherhand, meltblown has relatively weak tensile properties but due to the smaller fibres and larger surface area taken up by the fibres, it has excellent wicking and barrier properties. So together, they can create a strong product which can also offer a barrier to fluids and particles.
Additionally, the combination of spunbond and meltblown materials means that the features of each can make up for the weaknesses of the other SMS has excellent physical properties as well as barrier qualities. Features include high tensile strength, softness, comfort, breathability, wearability, and is also lightweight.
It also acts as a water-repellent, and a barrier against bacteria, blood and other liquids as well as gas/steam perspiration. Finally, it is also fine enough to serve as a disposable fabric.
The applications for SMS fabric?
- Filtration– this is a huge market for SMS and includes surgical face masks, gas and liquid filtration as well as cartridge filters.
- Insulation– SMS has wide ranging insulation uses including for example acoustic insulation in dishwashers.
- Medical healthcare and sanitary products– As SMS can be treated with additional repellents to withstand for example alcohol, oil and blood, this makes it an excellent fabric for the medical industry. Typical uses being surgical drapes, gowns, sterilization wraps, disposable patient sheets, female sanitary products, nappies and incontinence products.
- Disposable healthcare range: A range of disposable healthcare products including disposable bedding, medical gowns, coveralls, face masks, caps, aprons, over-sleeves and overshoes.
- Different use: With the development of SMS it is thought that it will grow rapidly in the market of nonwovens and become more and more popular for various segments including apparel, geotextiles, furnishings, roofing; Agriculture as well as many others.
The production process of SMS fabric
To make SMS fabric Polypropylene (PP) is needed as main raw material. PP manufacturing is an individual process; the SMS fabric mill needs to buy PP from fiber mill to make SMS fabric. Here is a short brief of PP:
PP- Polypropylene and its Manufacturing Process
Polypropylene is currently one of the fastest growing polymers. Much of this growth is attributed to polypropylene’s ability to displace conventional materials (wood, glass, metal) and other thermoplastics at lower cost.
Polypropylene (PP) is a tough, rigid plastic and produced in a variety of molecular weights and crystallinity.
Polypropylene is made from the polymerization of propylene gas in the presence of a catalyst system, usually Ziegler-Natta or metallocene catalyst. Polymerization conditions (temperature, pressure and reactant concentrations) are set by the polymer grade to be produced.
To produce PP various production processes exist with some general similarities. They are taking place either in a gas-phase (fluidized bed or stirred reactor) or a liquid-phase process (slurry or solution). The gas-phase polymerization is economical and flexible and can accommodate a large variety of catalysts. It is the most common technology in modern polypropylene production plants. Relevant technologies are Novolen®, Unipol® (gas-phase processes), Borstar® and Spheripol® (liquid-phase processes) and other Asian.
SMS fabric manufacturing Turnkey project details
- Fabric GSM: 10-100 grams / square meter.
2. Finished Fabric Width: 1.6 to 3.2 meters.
3. Color: Can according to customer’s production version of the color.
4. Design: Machine provide DOT patterns, cross pattern, Canberra, mouth the word pattern, a small DOT pattern, the appearance of a triangle pattern of five non-woven products and plastic film.
- Raw Material: The main raw materials is PP, Additives; Masterbatch
- Speed: 500 Meter/Min
- Daily Output (kg/day): 11000 kg to 20000 Kg (single line)
- Power consumption 400 kW to 550kw; 380V
- Space Require: Total length 15m/width 8m/height 6m (Approximate)
- Filament Denier: 1.5-2.0d/2-55um
- Process loss: Almost 0%.
Flow Chart of Production Line
Advantage of this project:
- No Need ETP
- No Need Steam or Gas Boiler
- Investment is half compared to the same capacity knit Composite.
Garments making process
To make the Biosafety Level-3 medical gown the sewing unit needs to use the Seam sealing machine to attach the synthetic tape. Other Plain and Overlock sewing machine also use.
Parameter of Seam sealing machine:
1. New type PC intellectual ultrasonic generator
2. Built-upper ultrasonic transducer
3. Pneumatic welding head lifting system
4. Rolling mold adjusting structure and arranging system
5. Special framework design with multi-practical functions.
6. Speed modulating system with single circuit motor
- Applied to the non-pin seam of chemical fiber fabrics, thermos-melt fabrics, non-woven surgical clothes and relative products, taking the place of sewing or down-press type welding, limitless continuous welding function, with solid weld, beautiful and high work efficiency.
2. Multi-functional framework system with the application of straight-line seam, turn seam and cylinder joining.
3. Roller design, add more strength and beautiful look to the product
- Product application: Lace dress, ribbons, decorative products, handkerchiefs, tablecloths, curtains, bedspreads, pillowcases, quilt, tents, raincoats, disposable surgical hat, woven masks, non-woven bags, etc.
The Total project investment cost depends on fabric width; production capacity, country of origin; machine brand, etc. However, the approximate investment cost maybe around 1.5 million USD to 4 million USD as per the capacity. And consider the 80% efficiency of the project investment will return in 2 years to a maximum of 3 years.
The Taffeta 210 fabric details will be published in the next issue… (To be continued…)