Type B bulk bag with liner

Abstract

A Type B bulk bag/liner assembly comprises a bulk bag formed from woven polypropylene fabric and a liner formed from “ADFLEX Q 100 F” (™) film.

Description

TECHNICAL FIELD

This invention relates generally to bulk bags, and more particularly to an assembly comprising a bulk bag fabricated from woven polypropylene fabric and having a plastic film liner which meets the definition of a Type B bulk bag.

BACKGROUND AND SUMMARY OF THE INVENTION

Flexible Intermediate Bulk Containers a/k/a FIBC's a/k/a bulk bags are divided into four categories, i.e., Types A, B, C, and D. Type A bulk bags comprise any standard bulk bag, with or without a liner, which is designed for use in environments comprising no explosion hazard caused by dusts, gases, vapors, or otherwise. Type C and Type D bulk bags are conductive and dissipative, respectively, and are used for sensitive explosive environments.

A Type B bulk bag comprises a bulk bag wherein the breakdown voltage of the combined fabric/coating/liner is less than 4 kilovolts. Breakdown voltage is defined as the amount of charge necessary to jump from a probe, through a combined material, to a grounded plate. According to the Swiss Institute for the Promotion of Safety and Security, a Type B bulk bag can be used in circumstances where there are explosive dusts having a minimum ignition energy (MIE) greater than 3 millijoules, but no explosive gases or vapors. MIE is defined as the lowest energy spark that can ignite a perfect mixture of the product, air, and whatever gases are present.

Most woven polypropylene fabrics, even with a 1 mil polypropylene coating, easily pass the four kilovolt test. However, heretofore it has not been possible to provide a bulk bag formed from woven polypropylene fabric having a plastic film liner which is capable of meeting the 4 kilovolt test. In most instances bulk bags comprising woven polypropylene fabric and a plastic film liner have a breakdown voltage in the range of between 10 kilovolts and 15 kilovolts, and therefore fail to pass the four kilovolt test by a considerable margin.

Some products require the use of a liner due to moisture sensitivity, D.O.T. requirements, or to prevent the sifting of fine particles through the seams of the bulk bag, but otherwise would not require a bulk bag having characteristics which would exceed those of a Type B bulk bag. Without the availability of a Type B bulk bag having a liner, the purchaser has no choice other than to use a Type C bulk bag having a conductive or anti-static liner. This necessity substantially increases packaging costs. Thus, a need exists for a bulk bag constructed from woven polypropylene fabric and provided with a plastic film liner which meets the definition of a Type B bulk bag by meeting or surpassing the four kilovolt breakdown voltage test.

The present invention comprises a Type B bulk bag with liner which overcomes the foregoing and other difficulties which have long since characterized the prior art. The bulk bag of the present invention is formed from conventional 5 ounce per square yard, uncoated woven polypropylene fabric. The liner is formed from a unique blown film resin marketed by Basell Polyolefins under the trademark “ADFLEX Q 100 F”. Testing by Chilworth Technology confirms that the fabric/liner combination utilized in the construction of the bulk bag of the present invention meets or exceeds the 4 kilovolt breakdown voltage test for Type B bulk bags in conditions of ambient relative humidity with only a few data points slightly above the 4 kilovolt level when the tests are conducted at very low humidity. More importantly, no propagating brush discharges (which could ignite explosive dusts) were observed during the testing. Ultimately, it is the absence of high energy propagating brush discharges that is the object of a Type B bulk bag since the 4 kilovolt breakdown voltage test is universally recognized as a very conservative standard.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had by reference to the following Detailed Description when taken in connection with the accompanying Drawings, wherein:

FIG. 1 is a perspective view of a bulk bag/liner combination incorporating the present invention in which certain component parts have been broken away more clearly to illustrate certain features of the invention; and

FIG. 2 is a diagrammatic sectional view taken the line 2-2 in FIG. 1 in the direction of the arrows in which certain parts have been omitted for clarity.

DETAILED DESCRIPTION

Referring now to the Drawings, and particularly to FIG. 1 thereof, there is shown a bulk bag 10 incorporating the present invention. The bulk bag 10 comprises four side walls 12, a top wall 14, and a bottom wall 16. However, as will be readily understood by those skilled in the art, the present invention is equally applicable to tubular bulk bags, U-panel bulk bags, and numerous other bulk bag constructions all of which are well known in the art.

The side walls 12, the top wall 14, and the bottom wall 16 comprising the bulk bag 10 are all formed from woven polypropylene fabric. More specifically, the side walls 12, the top wall 14, and the bottom wall 16 are formed from conventional 5 ounce per square yard uncoated woven polypropylene fabric. The side walls 12, the top wall 14, the bottom wall 16, and the other components of the bulk bag 10 are joined one to another by sewing along sew lines 17 in the conventional manner. Conventional lift loops 18 may be provided at the upper corners of the bulk bag 10.

The top wall 14 of the bulk bag 10 includes a conventional fill chute or spout which is also formed from woven polypropylene fabric. The fill chute or spout typically comprises a right circular cylinder extending upwardly from the center of the top wall 14, however, other fill chute configurations are known in the art. The bottom wall 16 includes a discharge chute or spout 19. The discharge chute or spout 19 typically comprises a right circular cylinder extending downwardly from the center of the bottom wall 16, although other discharge chute configurations are known in the art.

A liner 20 extends through the interior of the bulk bag 10. The liner 20 comprises a formed liner having exterior dimensions which are closely matched to the interior dimensions of the bulk bag 10. The liner 20 includes a fill chute portion 24 which extends through the fill chute of the top wall 14 of the bulk bag 10, and a discharge chute portion 28 which extends through the discharge chute 18 of the bottom wall 16 of the bulk bag 10.

Referring simultaneously to FIGS. 1 and 2, the liner 20 comprises side walls 22 which extend parallel to and which are closely spaced relative to the side walls 12 of the bulk bag 10. Although the phenomenon which affords the bulk bag/liner combination of the present invention the ability to provide the previously unattainable Type B bulk bag results in a bulk bag/liner combination is not fully understood, it is theorized that the close spatial relationship between the side walls 12 of the bulk bag 10 and the side wall 22 of the liner 20 may contribute thereto.

The liner 20 is fabricated from the polyolefin material manufactured by Basell Polyolefins and sold by that company under the trademark “ADFLEX Q 100 F”. A further description of such material is provided on the following page.

The following tests results demonstrate the fact that the bulk bag/liner of the present invention achieves the 4 kilovolts breakdown voltage requirement for a Type B bulk bag/liner assembly:

Although preferred embodiments of the invention have been illustrated in the accompanying Drawing and described in the foregoing Detailed Description, it will be understood that the invention is not limited to the embodiments disclosed but is capable of numerous rearrangements, modifications, and substitutions of parts and elements without departing from the spirit of the invention.

Claims

1. A Type B bulk bag assembly comprising: a bulk bag formed from at least one panel comprising woven polypropylene fabric; and a liner for the bulk bag comprising polyolefin film formed from “ADFLEX Q 100 F” (™) film.

2. The bulk bag assembly according to claim 1 wherein the bulk bag comprises four side walls, a top wall, and a bottom wall, and wherein the liner comprises a formed liner including side walls each positioned closely adjacent to and extending substantially parallel to one of the side walls of the bulk bag.

3. The bulk bag assembly according to claim 1 wherein the bulk bag comprises 5 ounce woven polypropylene fabric and wherein the liner comprises a blown film.

4. In combination with a bulk bag formed from woven polypropylene fabric and comprising at least one side wall, a top wall, and a bottom wall, the improvement comprising: a liner for the bulk bag comprising polyolefin film formed from “ADFLEX Q 100 F” (™) film and including at least one side wall positioned closely adjacent to the side wall of the bulk bag; the combination of the bulk bag and the liner comprising a Type B bulk bag assembly.

5. The bulk bag assembly according to claim 5 wherein the bulk bag comprises four side walls, a top wall, and a bottom wall, and wherein the liner comprises a formed liner including four side walls each positioned closely adjacent to and extending substantially parallel to one of the side walls of the bulk bag.

6. The bulk bag assembly according to claim 5 wherein the bulk bag comprises 5 ounce woven polypropylene fabric and wherein the liner comprises a blown film.

7. A Type B bulk bag/liner combination comprising: a bulk bag comprising four side walls, a top wall, a fill chute extending upwardly from the center of the top wall, a bottom wall, and a discharge chute extending downwardly from the center of the bottom wall; and a liner for the bulk bag comprising polyolefin film formed from “ADFLEX Q 100 F” (™) film and including four side walls each extending parallel to and positioned closely adjacent to one of the side walls of the bulk bag, a fill chute extending through the fill chute of the bulk bag, and a discharge chute extending through the discharge chute of the bulk bag.

8. The bulk bag assembly according to claim 7 wherein the bulk bag comprises 5 ounce woven polypropylene fabric and wherein the liner comprises a blown film.

9. The bulk bag according to claim 8 wherein the side walls, the top wall, the fill chute, the bottom wall, and the discharge are joined one to another by sewing.

10. The bulk bag/liner combination according to claim wherein the liner comprises a formed liner.