DESC:TILE OF THE INVENTION: A TYPE D FLEXIBLE INTERMEDIATE BULK CONTAINER FABRIC
FILED OF THE INVENTION
The present disclosure is generally related to Flexible Intermediate Bulk Container fabric. Particularly, the present disclosure is related to a Type D Flexible Intermediate Bulk Container fabric. More particularly, the present disclosure is related to a Type D Flexible Intermediate Bulk Container fabric, which does not comprise quasi-conductive fabric/yarn/filament with anti-static coatings.
BACKGROUND OF THE INVENTION
When powders and bulk solids are handled and processed, they can generate electrostatic charge. The mechanism by which this charge is generated is known as triboelectrification or contact electrification. Triboelectrification occurs when two surfaces come into contact and then quickly separate. There is a rearrangement of electrons at the point of contact. One surface is left with a surplus of electrons and is said to be negatively charged, while the other surface is has a deficit of electrons and is said to be positively charged. When one or both of the surfaces is electrically insulating, the resistivity of the insulating surface limits recombination by inhibiting charge mobility. As a result, a net charge remains on the insulating surface(s).
Powders and bulk solids have a propensity to generate static charge because many are insulating in electrostatic terms and the surface area available for triboelectrification increases with decrease in particle size. The generation of electrostatic charge is generally not in and of itself hazardous. However, if static charge is allowed to accumulate, it can give rise to electrostatic discharges. Static discharges can pose an ignition risk if they occur in the presence of a flammable gas, vapour, or dust atmosphere. They may also pose a nuisance to personnel. Accumulated charge can also cause processing and quality problems by causing powders and bulk solids to agglomerate or adhere to equipment and vessel walls. Electrostatic charge can accumulate on: (a) metal plant and equipment isolated from electrical ground, such as metal piping, ductwork, flanges, fittings, vessels, and containers; (b) personnel isolated from ground by electrically-insulating footwear or flooring; and (c) electrically-insulating materials and items, such as plastic scoops, liners, and containers including Flexible Intermediate Bulk Containers.
The filling and emptying of Flexible Intermediate Bulk Containers is often characterized by the generation of high levels of static charge due to the nature and scale of the operations and the electrically insulating nature of the materials involved. As highly charged insulating bulk solids accumulate, the electric field along the surface of the accumulating material intensifies – a phenomenon known as charge compaction. The strong electric field causes the ionization of the air just above the material surface and the acceleration of oppositely charged ions away from the bulking solid, sometimes giving rise to cone-type electrostatic discharges.
There are four types of Flexible Intermediate Bulk Containers, namely Type A, Type B, Type C, and Type D. Type D Flexible Intermediate Bulk Containers do not require grounding and can be used to transport flammable powders.
Existing Type D Flexible Intermediate Bulk Containers are constructed from woven fabric panels, including quasi-conductive fibre/thread, in which the base fabric is coated including antistatic additives, and sewn together with yarns including quasi-conductive fibre, conductive fibre, or standard sewing yarn. However, such Flexible Intermediate Bulk Containers are susceptible to failure if the coating becomes removed during use. As a result, care must be taken to preserve the integrity of the coating.
However, the tensile strength of such quasi-conductive fibre/thread is quite low. Flexible Intermediate Bulk Containers are meant for rough handling during transportation and pass through lot of friction, and the possibility of the quasi–conductive fibre/thread breaking is quite high.
There is, therefore, a need in the art for a robust Type D Flexible Intermediate Bulk Container fabric that overcomes the aforementioned drawbacks and shortcomings.

SUMMARY OF THE INVENTION
A Type D Flexible Intermediate Bulk Container fabric is disclosed. The Type D Flexible Intermediate Bulk Container comprises a first tape; a second tape; and a lamination for laminating the second tape.
The first tape is woven into a fabric, and comprises: 90% to 98% of polypropylene with a melt flow index in the range of one to five; 0% to 8% of calcium carbonate as a filler, with the combination of 20% to 30% polypropylene or low density polyethylene and remaining content of calcium carbonate; 1% to 4% of an ultraviolet masterbatch with an effective UV of 20%; and 1% to 3% of a colour masterbatch to impart a required colour and differentiate the first tape from the second tape that is configured to possess antistatic properties.
The second tape that is configured to possess antistatic properties is weaved in both vertical and horizontal directions to obtain uniform charge decay, and comprises: 50% to 70% of polypropylene; 1% to 3% of the ultraviolet masterbatch with an effective UV of 20%, 0% to 3% of a filler; 25% to 40% of an antistatic masterbatch; and 1% to 3% of a colour masterbatch.
The lamination for laminating the second tape comprises: 70% to 75% of polypropylene; 20% to 30% of the antistatic master batch; and 5% to 10% of a compatibilizer.
The disclosed Type D Flexible Intermediate Bulk Container fabric is: cost-effective as a single polyolefin is used to manufacture the fabric and the lamination; 100% recyclable as it is made of a single polymer and does not have quasi-conductive threads; more efficient than existing Type D Flexible Intermediate Bulk Container fabric (has a better breakdown voltage and can withstand up to 1500 kg with a safety factor of 5:1); and is more durable than existing Type D Flexible Intermediate Bulk Container fabric (the second tape is inside the Type D Flexible Intermediate Bulk Container fabric).
Further, the existing machinery that is used for the production of Flexible Intermediate Bulk Container fabric can also be used to produce the disclosed Type D Flexible Intermediate Bulk Container fabric.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates an embodiment of a Type D Flexible Intermediate Bulk Container fabric, in accordance with the present disclosure.
Figure 2 illustrates the results of a surface resistivity test, in accordance with the present disclosure.
Figure 3 illustrates the results of a surface resistivity test, measured in both unlaminated and laminated surface, in accordance with the present disclosure.
Figure 4 illustrates the results of a fast charge decay test, in accordance with the present disclosure.
Figure 5 illustrates the results of a breakdown voltage test, in accordance with the present disclosure.
Figure 6 illustrates the results of a propagating brush discharge test, in accordance with the present disclosure.
Figure 7 illustrates a Type D Flexible Intermediate Bulk Container, in accordance with the present disclosure.
Figure 8 illustrates the results of a discharge incendivity test, in accordance with the present disclosure.
Figure 9 illustrates the results of another discharge incendivity test, in accordance with the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
Throughout this specification, the disclosure of any range is to be construed as being inclusive of the lower limit of the range and the upper limit of the range.
Throughout this specification, the disclosure of any percentage is to be construed as percentage by weight, unless otherwise mentioned.
A Type D Flexible Intermediate Bulk Container fabric is disclosed. As illustrated in Figure 1, the Type D Flexible Intermediate Bulk Container fabric comprises a first tape that is woven into a fabric (woven antistatic fabric layer), a second tape that is configured to possess antistatic properties, said second tape being weaved in both vertical and horizontal directions to obtain uniform charge decay, and a lamination for laminating the second tape (antistatic laminated layer). After various trials, it has been found that the basic requirement to produce Type D or dissipative Flexible Intermediate Bulk Container fabric is to keep the surface resistivity in one or both the surfaces in the semi-conductive range.
In an embodiment of the present disclosure, the first tape comprises 90% to 98% of polypropylene with a melt flow index in the range of one to five; 0% to 8% of calcium carbonate as a filler, with the combination of 20% to 30% polypropylene or low density polyethylene and remaining content of calcium carbonate; 1% to 4% of an ultraviolet masterbatch with an effective UV of 20%; and 1% to 3% of a colour masterbatch to impart a required colour and differentiate the first tape from the second tape that is configured to possess antistatic properties.
In another embodiment of the present disclosure, the first tape is woven as a fabric with a breakdown voltage that is less than 6 Kv by using circular or flat loom, and the fabric grams/meter (GSM) varies from 90 GSM to 275 GSM.
In yet another embodiment of the present disclosure, the second tape that is configured to possess antistatic properties comprises 50% to 70% of polypropylene; 1% to 3% of the ultraviolet masterbatch with an effective UV of 20%, 0% to 3% of a filler; 25% to 40% of an antistatic masterbatch; and 1% to 3% of a colour masterbatch.
In yet another embodiment of the present disclosure, the antistatic masterbatch comprises polypropylene, one or more antistatic additives, and one or more thermoplastic elastomers.
Any suitable commercially available antistatic masterbatch may also be used.
In yet another embodiment of the present disclosure, the ultraviolet masterbatch comprises 15% to 20% of a polymer additive; 30% to 40% of NSDS as a nano filler; and 30% of polypropylene as a carrier material.
In yet another embodiment of the present disclosure, the width of the second tape that is configured to possess antistatic properties is between 1.5 mm and 3.5 mm.
In yet another embodiment of the present disclosure, the second tape that is configured to possess antistatic properties is placed every 2 cm to 4 cm in the horizontal direction by adding the tapes in a uniform pattern through a warp creel.
In yet another embodiment of the present disclosure, the second tape that is configured to possess antistatic properties is placed every 1.5 cm to 4 cm in weft throughout the width of the fabric.
In yet another embodiment of the present disclosure, the surface resistivity of the second tape is between 109 ohms and 1012 ohms.
In yet another embodiment of the present disclosure, the lamination comprises 70% to 75% of polypropylene; 20% to 30% of the antistatic master batch; and 5% to 10% of a compatibilizer.
The first tape is manufactured by melting the material through extrusion to form a film, which subsequently passes through a quenching tank. The film is split into tape by a splitter, and the tape passes through a hot oven, with the input tape speed and the output tape speed inside the oven differing in the range of 1:5 to 1:8 (stretching takes place). The temperature in the melting zones and the oven are fine-tuned to get a required tensile strength, tape width, and denier. The output from the hot oven is converted into bobbin by winding on cheese tube through winders.
The first tape is produced in the temperature range of 200 degrees Celsius and 290 degrees Celsius, starting from extruder feed zone, die zone using suitable filter for better homogenization, and mixing of various components. The quenching tank water is maintained at 30 degrees Celsius to get maximum cooling of film. The stretch ratio and hot oven temperature are configured to get maximum stretch ability (from 6 to 8) to achieve the maximum tensile strength
During the manufacture of the second tape, the temperature is controlled to avoid any decomposition of antistatic ingredients during extrusion. The stretch ratio and the oven temperature are configured to retain surface resistivity.
For the production of the second tape, the extruder is operated at temperatures between 170 degrees Celsius and 260 degrees Celsius, with a reduced filter mesh to avoid frication and decomposition during extrusion, while, at the same time, the antistatic net structure is kept intact.
The stretch ratio is configured to be lower compared to that for the first tape; this ensures that the surface resistivity can be maintained without compromising on the tensile strength.
For lamination, the fabric is sent in between a rubber roller and a steel roller and, at the same time, the hot molten film from extrusion is applied on the fabric surface. The antistatic masterbatch is dried for at least six hours to remove any moisture.
The process parameters for lamination are configured to avoid any increase in temperature, which will destroy the film formation and the quality of the film. The temperature of the extruder is between 160 degrees Celsius and 250 degrees Celsius. The outcome film is maintained at 170 degrees Celsius to get uniform film and also to retain the static structure on the film. A lamination speed of 40 - 50 meters/minute and chill roll temperature of 28 degrees Celsius are maintained to achieve best results.
In yet another embodiment of the present disclosure, the fabric is laminated by applying 20 - 30 GSM coating in a lamination plant with the combination of raw materials that has been disclosed above for lamination.
In yet another embodiment of the present disclosure, the Type D Flexible Intermediate Bulk Container fabric may not comprise the lamination (antistatic laminated layer).
The Type D Flexible Intermediate Bulk Container fabric was tested based on IEC 61340-4-4 using a flammable atmosphere having a MIE (Minimum Ignition Energy) of 0.14+/-0.01 mj. This MIE was achieved using a mixture of 5.4% (v/v) ethylene in air. The test results were found to be suitable to fill and transport high static material, flammable powders, etc. Further testing is underway.
The surface resistance of the disclosed Type D Flexible Intermediate Bulk Container fabric is indicated in Figure 2 (in accordance with DIN IEC 93), with the following being the test conditions: Ambient R.H. (52% R.H., 22°C/71°F), and Low R.H. (20% R.H., 23°C/73°F).
Figure 3 illustrates the surface resistivity of the Type D Flexible Intermediate Bulk Container fabric measured in both unlaminated and laminated surface, in both Ambient R.H (52% R.H., 22°C/71°F), and Low R.H. (20% R.H., 23°C/73°F).
Figure 4 illustrates the fast charge decay of the Type D Flexible Intermediate Bulk Container fabric, with no residual voltage being detected.
Figure 5 illustrates the breakdown voltage test results of the Type D Flexible Intermediate Bulk Container fabric (Dull side - unlaminated, Shiny side - laminated).
Figure 6 illustrates the propagating brush discharge test results i.e. attempt to produce propagating brush from an eletrostatically charged sample by using corona charging probe, grounding electrode, and high voltage power source (Dull side - unlaminated, Shiny side - laminated).
A Type D Flexible Intermediate Bulk Container made with the disclosed fabric is illustrated in Figure 7. The Type D Flexible Intermediate Bulk Container comprises: a top spout or filling spout (1); a lifting loop (2) that comprises three to five rows of the second tape; a main body that is made of the second tape in warp (3) and weft (4); an outlet or discharge (5); and a tie tape (6) that is associated with the filling spout (1) and the outlet or discharge (5) and facilitates to tie the filling spout (1) and the outlet or discharge (5).
Figure 8 illustrates the results of a discharge incendivity test (based on -IEC 61340 -4-4) conducted on a Type D Flexible Intermediate Bulk Container made with the disclosed fabric, using the following and under the following conditions:
Electronic field meter; high voltage power supply with high voltage corona probe; insulated frame; and gas probe
Room temperature - 22.2 degrees Centigrade with 50 % RH
Gas flow rate – 12.6 L/min (mixture of 5.4% ethylene and 94.6% Dry air)
MIE – 0.14 +/- 0.01 mj
Corona charging = - 13.16 Kv
Figure 9 illustrates the results of a discharge incendivity test (based on -IEC 61340 -4-4) conducted on a Type D Flexible Intermediate Bulk Container made with the disclosed fabric, using the following and under the following conditions:
Electronic field meter; high voltage power supply with high voltage corona probe; insulated frame; and gas probe
Room temperature - 24.5 degrees Centigrade with 20 % RH
Gas flow rate – 12.6 L/min (mixture of 5.4% ethylene and 94.6% Dry air)
MIE – (0.14 +/- 0.01 mj
Corona charging = - 13.16 Kv
EXAMPLE:
FIRST TAPE:
Polypropylene - 93% with a MFI 3.4
Filler - Carrier material of Poly Propylene with 70% of calcium carbonate
White Master Batch – Carrier material of LDPE with 40% of Titanium dioxide as a coloring agent to get white color
UV Additives - Carrier material of LDPE with 20 % of active ingredient of UV stabilizer
SECOND TAPE:
Polypropylene - 67 % with a MFI of 3.4
Antistatic Master Batch - Carrier material of Polypropylene with 30% of static dissipative polymeric additive
Green Colour Master Batch – Carrier material of LDPE with 20% green pigment
UV additives - Carrier material of LDPE with 20% of active ingredient of UV stabilizer
LAMINATION:
Polypropylene - 70% - MFI range of 35 - 55
Antistatic Master Batch - Carrier material of Polypropylene with 25% of static dissipative polymeric additive
Compatibilizer - 5 %
The disclosed Type D Flexible Intermediate Bulk Container fabric is: cost-effective as a single polyolefin is used to manufacture the fabric and the lamination; 100% recyclable as it is made of a single polymer and does not have quasi-conductive threads; more efficient than existing Type D Flexible Intermediate Bulk Container fabric (has a better breakdown voltage and can withstand up to 1500 kg with a safety factor of 5:1); and is more durable than existing Type D Flexible Intermediate Bulk Container fabric (the second tape is inside the Type D Flexible Intermediate Bulk Container fabric).
Further, the existing machinery that is used for the production of Flexible Intermediate Bulk Container fabric can also be used to produce the disclosed Type D Flexible Intermediate Bulk Container fabric.
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations and improvements without deviating from the spirit and the scope of the disclosure may be made by a person skilled in the art. Such modifications, additions, alterations and improvements should be construed as being within the scope of this disclosure.
LIST OF REFERENCE NUMERALS
1 – Top Spout or Filling Spout
2 – Lifting Loop
3 – Antistatic Tape in Warp
4 – Antistatic Tape in Weft
5 – Outlet or Discharge
6 – Tie Tape ,CLAIMS:1. A Type D Flexible Intermediate Bulk Container fabric, comprising:

a first tape that is woven into a fabric, said first tape comprising:

90% to 98% of polypropylene with a melt flow index in the range of one to five;
0% to 8% of calcium carbonate as a filler, with the combination of 20% to 30% polypropylene or low density polyethylene and remaining content of calcium carbonate;
1% to 4% of an ultraviolet masterbatch with an effective UV of 20%; and
1% to 3% of a colour masterbatch to impart a required colour and differentiate the first tape from the second tape that is configured to possess antistatic properties;

a second tape that is configured to possess antistatic properties, said second tape being weaved in both vertical and horizontal directions to obtain uniform charge decay, and said second tape comprising:

50% to 70% of polypropylene;
1% to 3% of the ultraviolet masterbatch with an effective UV of 20%,
0% to 3% of a filler;
25% to 40% of an antistatic masterbatch; and
1% to 3% of a colour masterbatch; and

a lamination for laminating the second tape, said lamination comprising: 70% to 75% of polypropylene; 20% to 30% of the antistatic master batch; and 5% to 10% of a compatibilizer.

2. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the first tape is woven as a fabric with a breakdown voltage that is less than 6 Kv by using circular or flat loom, and the fabric grams/meter varies from 90 GSM to 275 GSM.

3. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the antistatic masterbatch comprises polypropylene, one or more antistatic additives, and one or more thermoplastic elastomers.

4. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the ultraviolet masterbatch comprises 15% to 20% of a polymer additive; 30% to 40% of NSDS as a nano filler; and 30% of polypropylene as a carrier material.

5. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the width of the second tape that is configured to possess antistatic properties is between 1.5 mm and 3.5 mm.

6. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the second tape that is configured to possess antistatic properties is placed every 2 cm to 4 cm in the horizontal direction by adding the tapes in a uniform pattern through a warp creel.

7. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the second tape that is configured to possess antistatic properties is placed every 1.5 cm to 4 cm in weft throughout the width of the fabric.

8. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the surface resistivity of the second tape is between 109 ohms and 1012 ohms.

9. The Type D Flexible Intermediate Bulk Container fabric as claimed in claim 1, wherein the fabric is laminated by applying 20 - 30 GSM coating in a lamination plant.

10. A Type D Flexible Intermediate Bulk Container made from the fabric as claimed in claim 1.