NEW ERA OF WOVEN SACK/FIBC TECHNOLOGY & DEVELOPMENT.

1.???Introduction:

Prof Giulio Natta who discovered in 1957 sterically ordered Polymeric chains of isotactic Polypropylene & HDPE (high density polyethylene) could be oriented in a linear direction. This characteristic with respect to annealing, temperature, stretch ratio and mode of extrusion led to the invention of Polyolefin oriented structures commonly called Flat tapes to be woven onto a loom to create the “Plastic Woven Sack” which the industry globally calls Raffia.

• ?Estimated at 40 billion USD, the global Raffia Industry has been growing at 5% CARG with an annual consumption of 16 million MTS of Polyolefin Polymers. Keeping up with the global trend, India’s Raffia industry too has achieved phenomenal growth in the last two decades. Today, the industry consumes more than 2 million MTS of polymer and has achieved an impressive size of Rs 30,000 crores, growing at the rate of almost 10% every year.?

?Growth in the Raffia industry is not just predictable but also desirable since it contributes to nearly the entire packaging solutions of bulk commodities like Cement, Fertilizer, Agricultural and Horticulture products, Chemicals, Polymers and building construction materials. No wonder, the growth in these industries is directly proportional to growth in the Raffia industry.

?Geographically, the global Raffia Industry is segmented into five key regions - North and Latin America, Europe, Asia Pacific, Middle East, and Africa. Both India and China have the capability and capacity to supply to the Middle East, Western Europe, and Latin American countries. European companies operating in supply and logistics are heavily importing from the Asia Pacific region. PP/HDPE woven fabrics and sacks provide strong, dependable, and economical packaging option for diverse industries across the globe. These sacks are light weight and ideally suited for bulk packaging almost all commodity products with appropriate protection. No wonder, PP/HDPE sacks are popular throughout the world.

The present paper describes the material selection criteria including additives for manufacture of PWS/FIBC, Processing of tapes, their weaving, advancements is manufacturing technology and machinery, applications, Quality Standards and lastly the sustainability of these products.

?2.???Material Selection Criteria for processing of Tapes:

The choice of materials of Polyolefins for manufacture of PWS/FIBC must be based on Melt Flow Index (MFI) which depends on average Molecular weight of the polymer and is expressed as a measure of flow 10gm/ 10 minutes.

For PP the range of MFI is from 1.6 to 6.0 gm/10 mts at 230 deg Celsius and for HDPE it is 0.75 to 1.0 gm/10mts at 190 degrees Celsius. The molecular distribution pattern is very important for material selection which must be neither very broad or very narrow. Crystallinity of the polymeric material have direct bearing on the mechanical properties like tensile strength, tenacity, elongation, and Flexural modulus. Material selection for extrusion coating is based on high MFI of Polyolefins to ensure fast flow rate. In case of PP Coating, it is 20 to 40 gm/10mts, LDPE and LLDPE Coating at 6 to 8 gms/ 10 mts. The threads used in PWS are generally based on PP Multifilament yarn 15 to 40 gm/10 mts and PP Monofilaments 3.5 gm/10mts or HDPE Monofilaments 0.9 to 1.2 g/ 10 mts. The Figs below give the Data sheets of PP /HDPE for raw material selection.

3.Additives used for tapes in manufacture of PWS/ FIBC

• ?Additives for plastics are materials which are incorporated into the monomer or polymer to improve the processing parameters and the performance of the finished plastic.
• They are added in small quantities to the basic resin.
• Additives selected for some specific purpose should not affect the other properties of the material.
• ?The additives selected should be compatible.
• It should have enough effectiveness for the purpose for which it is selected.
• It should not toxic, non-corrosive and odourless.
• Cost as low as possible.
• Most of Additives used during plastics Processing operation (Extrusion, Injection molding) are in compounded granular/pellet form (Masterbatch).
• In general, Color concentrate compounded with a Polymer carrier (PE or PP) in granular form termed as Masterbatch.

Now, most of additives (Filler, Color, UV, Processing aid etc.) are available in the form of Masterbatch with a “base” carrier resin.

Additional used for process of PWS/FIBC are-

Anti-fibrillation Master batch (AFMB)/Filler Master batch – CaCO3, (to prevent splitting of tapes, known as Fibrillation), Talc, Mica etc.

?UV Stabilizer (HALS, carbon black)

Process Stabilizers/Aid/Lubricants for improving adhesion between Filler & Plastics, better dispersion, improved flow & melt homogeneity.

White Master batch (TiO2 based), optical brightener or Colorants for imparting color.

? 4.0 Manufacturing of Plastic woven sack/FIBC-

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Plastic woven sack/FIBC are manufactured in the process as given in the figure below-Polymer granules are fed in tape line melted/stretched/annealed to make flat tape which are wound on winder and finally woven into a fabric based on mesh (Linear Density).

The roll fabrics may be laminated, printed & converted into Bags.

?4.1 Basic Machinery requirements for PWS

?????Tape plant with matching numbers of Winders

?????Looms (Shuttle type- Circular)- (no of looms as per capacity of tape plant)

?????Lamination /Extrusion coating (as per product spec)

?????Multifilament yarn extrusion (sewing thread/PP MFY)

?????Conversion machines (BCS, Valvomatic)

?????Printing machine

?????Utilities, Auxiliaries, Bale press etc.

4.2 Plastic Extrusion Process-

4.3 Advance is in Tape line Processing Machine-

Lohia’s?lorex series of tape extrusion lines are based on the conventional single stage stretching process and have been serving the Raffia Industry for over three decades. The technology has been perfected over time and today these machines have set the benchmark for efficiency and performance.

?Lohia’s?duotec?series of tape extrusion lines process involves a unique double stage stretching in which the tapes undergo a pre-stretch before entering the hot air oven for the final stretch, resulting in better?run ability?and flexibility to improve any one or a mix of factors such as working speed, efficiency, process stability and tape properties.

Lohia’s?CoEx latest innovative technology which enables production of composite multilayer laminar structured slit film tapes by feeding two melt streams from two different extruders to a feed block where they merge into a single laminar structure.

4.4 Development and advances in Circular weaving in loom technology-

4.5 Coating / Lamination-

Solo print, Flexographic Printing Press combines Lohia Corp’s domain expertise with the technological capabilities of Pelican Rotoflex Pvt. Ltd.

This 6-color printing press, equipped with new generation electronics, is distinctively designed, and precisely machined for an accurate and dependable performance over its long life.

4.6 Bag/ Sack conversion line System based on the requirement of the bag,?

5.0 Flexible Intermediate Bulk Containers (FIBCs) is very important segment of raffia sector are also called as big bags, are the large size, box shape bags fabricated from thick, and UV stabilized, coated or uncoated raffia fabrics, with integrated lifting devices for bag handling. FIBCs are one of the most cost effective and ideal types of packaging for shipping and storing dry bulk products. FIBCs are available for powdered and granular materials like chemicals, petrochemicals, minerals, building materials, fertilizers, foods gains, etc.

?India is the largest exporter of FIBCs to the global market, with major supplies to North America, Europe, and Australia. The domestic FIBC industry has recorded an admirable growth in last two decades and the present export share is around 30% of the global FIBC consumption 1240 KTA. The major factors contributed for this growth are the local availability of raw materials including speciality high tenacity grades, efficient machinery with latest technology, skilled manpower specially for the FIBC fabrication process, stringent quality norms and, the long reputation of supply of high quality FIBCs to the global market.

?6.0 Specification of PP Tapes for PWS/FIBC-

·???????The minimum linear density of the tape shall be 66.6 tex (600 denier).

·???????The tenacity of the tapes shall not be less than 40.5 g/tex (4.5 g/denier)

·???????The elongation of the tape at the point of rupture shall not be less than 15 %.

·???????Width The finished width of the tape shall be as agreed to between the buyer and the seller or as declared. However, the finished width shall not exceed 5.0 mm and shall be subject to a tolerance of +/- 5 percent on agreed/declared.

·???????The thickness of the tape shall correspond to the linear density and width.

·???????FIBC linear density is from 1800-4000 denier.

7.0 HDPE/PP Raffia Woven for Bulk Packaging Applications:

Woven sacks are the most used packaging material for mass distribution of commodity materials in industry, accounting for about 60 per cent of the product shipped to consumers and end-users. Following are major raffia products are used for bulk packaging of commodity materials:

Cement Packaging Sacks: Currently, uncoated, sewn woven polypropylene sacks form the major share of cement packaging material.

Variation in sack size also leads to issues related to stacking, storing, and transporting. Furthermore, cement oozing from the uncoated sacks and sack busting during handling and transport are some of the serious issues in terms of environmental aspect are commonly observed for traditional polypropylene woven sacks. Moreover, these sacks also have very poor moisture resistance resulting in spoilage of packed cement?

Advantages of block bottom valve sacks are.

·???????High level of sack manufacturing process automation - 50% less manpower requirement

• ·???????About 20% less raw material and 15% less energy requirement
• ·???????About 30% higher value addition
• ·???????No seepage or oozing of cement
• ·???????Better stacking and handling of bags
• ·???????Better logistics of packed cement due to high automation possibility
• ·???????Product differentiation
• ·???????Temper proof packing

·???????Aesthetically superior with branding and printing

Flexible Intermediate Bulk Containers (FIBCs)

India is the largest manufacturer and exporter of FIBCs to global market, with major supplies to Europe, North America, and Australia.

Advantages of FIBCs:

• ?Low cost of material handling.
• ?Easy filling and discharge of material.
• Saving in loading/unloading time due to ease of handling.
• Possibility of automation to reduce manpower Built in safety factor of at least 5:1 on nominal load.
• Moisture sensitive material can be stored and transported using inner liners with barrier property
• Eco- friendly since product is reusable and recyclable.

Conclusion-?

??Plastic woven sack/FIBC are versatile material suitable for Bulk packaging of commodities with Sustainability.

?Generally, almost 1.8 MMT are being consumed for this Industry.

??In recent year technological advancement have been made in polymeric materials, additives, Processing machinery and end-product use.

The industry is growing for a bright future globally as high growth.

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