Heavy-duty plastic bag with easy tear corner spout portion

Description

TECHNICAL FIELD

The present invention relates to a heavy-duty plastic bag having a novel spout opening defined by a perforated tear line profile formed in a top corner portion of the bag to dispense a granular product from the bag at an improved dispensing rate.

BACKGROUND ART

Reference is made to our earlier issued U.S. Pat. No. 5,636,925 which describes a heavy-duty bag of the type forming the subject matter of the present application and which was developed to contain granular products in quantities of from about 25 lbs to 40 lbs (pounds). More specifically, this bag was developed to contain granular salt pellets which are used in water softeners. These bags are typically manufactured from extruded linear low density polyethylene and low density polyethylene plastic film in a tubular form and the upper and lower open ends of the tube are heat sealed in a conventional manner to provide a strong and durable closure at the top and bottom of the bags with one of the seals being formed after the bag is filled with the product. It is also essential that these bags withstand drop tests with the bags filled with the product that it is intended to contain. The drop tests are performed at distances of approximately 4 feet above a hard floor surface without rupturing the plastic film of the bag or the perforated corner portion which is detachable to form a spout. Accordingly, these bags must be made fairly sturdy and for this purpose the film has a thickness of approximately 4 to 8 mils.

Various perforated spout designs have been developed for such bags, with an arcuate perforated tear spout corner portion illustrated in U.S. Pat. No. 5,482,376. Straight line perforated tear tab designs have also been suggested in the past and two of these are described in U.S. Pat. No. 6,402,379. One of the problems with these corner tear spout portions is that they are relatively difficult to tear by hand. In order to alleviate this problem the perforated tear line has a slit formed in the top edge or the top flap edge of these bags. However, with the straight line profiles of some of these tear tabs the transition zones of the straight line perforations are too abrupt and therefore because the tear strength of the plastics material is lowest in the machine direction, the tearing may not follow an abrupt transition zone and continue to tear in the machine direction causing a large irregular tear opening resulting in spillage of some of the contents and making it difficult to pour the contents. The configuration of the spout openings formed by these tear lines also provide configurations wherein the material cannot be dispensed at a rapid rate thus causing the user person to support the bag for longer periods of time during the dispensing of the product from the bag. This is particularly so with bags containing granular salt pellets wherein the bag must be supported at a height of three to four feet whereby the material can be dispensed in a top opening of the water softening container. This can be a fairly hazardous task for the female gender or older individuals having stability problems or weak muscular frames.

Other disadvantages of prior art bags is that some of these are not provided with handle portions making it even more difficult to manipulate the bag while dispensing the granular product from the corner spout opening. In order to improve the tearing of the spout corner portion various perforation ratios have been suggested and including ratios which vary along the tear line of the perforation. However, as stated hereinabove the perforation needs to be strong enough to withstand the drop tests of these bags to not accidentally rupture in this weakened zone.

SUMMARY OF THE INVENTION

It is a feature of the present invention to provide a heavy-duty plastic bag which is adapted to contain a granular product and which is provided with an easy tear perforated corner spout portion having a tear line profile which provides for an improved pour time over prior art bags of the same type.

Another feature of the present invention is to provide a heavy-duty plastic bag adapted to contain a granular product, such as salt pellets, and wherein the bag is easy to manipulate with a content of from about 25 lbs to 40 lbs when supported at a height of at least waist high or higher to dispense the salt pellets into a container.

Another feature of the present invention is to provide a heavy-duty plastic bag adapted to contain a granular product and wherein the tear line profile is formed of perforations having a ratio of 1:1 and a starter slit opening at a top end to provide easy removal of the perforated corner spout portion.

Another feature of the present invention is to provide a heavy-duty plastic bag adapted to contain a granular product and wherein the tear line profile is defined by a first straight line segment extending downwardly from a top edge of the bag at an angle with respect to a near side edge of the bag and which merges into a concavely curved transition segment which connects to a second straight line segment extending downwardly from the transition segment at an angle with respect to the near side edge of the bag and terminates at the side edge.

Another feature of the present invention is to provide a heavy-duty plastic bag adapted to contain a granular product and which has a tear line profile as above described and wherein the transition segment is approximately 15% of the total length of the perforated tear line profile and wherein the resistance of the perforation all along the tear line profile is substantially constant.

According to the above features, from a broad aspect, the present invention provides a heavy-duty plastic bag adapted to contain a granular product. The bag has a front and rear wall, an open bottom edge adapted to be sealed after the granular product is dispensed in the bag. A heat sealing strip is spaced adjacent a top edge of the bag and forming a skirt portion between the heat sealing strip and the top edge. A pouring spout is defined in a top corner of the bag by a detachable corner portion delineated by a perforated tear line profile formed in juxtaposition in the front and rear walls. The tear line profile defines a first straight line segment extending downwardly from the top edge of the front and rear walls and angulated at an angle with respect to the top edge in the direction of a near one of the opposed side edges. The first straight line segment merges into a concavely curved transition segment to connect to a second straight line segment extending downwardly from the transition segment at an angle with respect to the near one of the opposed side edges and terminates at the near one of the side edges. The concavely curved transition segment has a length which is approximately 15% (fifteen percent) of the total length of the perforated tear line profile. The perforated tear line profile is formed by a constant and equal cut-to-uncut perforation ratio. The perforated tear line profile further terminates at the top edge in a slit extending through the skirt portion between the top edge and the heat sealing strip.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a partly fragmented plan view of the heavy-duty plastic bag constructed in accordance with the present invention and showing the bag prior to filling;

FIG. 2 is an enlarged plan view showing the configuration of the tear line profile and its dimensions and the angular orientation of the straight line segments and the concavely curved transition segment;

FIG. 3 is a perspective view showing the bag with the corner spout portion having been torn off and the granular product being dispensed by a user person;

FIG. 4 is a side view of the perforation slit forming blade used to make the perforation and slit of the tear line profile;

FIG. 5 is a simplified side view showing the die assembly with the slit forming blade assembled thereto; and

FIG. 6 is a perspective view, partly fragmented, further illustrating the construction of the die assembly.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIGS. 1 to 3 there is shown generally at 10, the heavy-duty plastic bag of the present invention and particularly adapted to contain a granular product 11, see FIG. 3, therein such as coarse salt pellets, fertilizers, sand, pet food, yeast, lawn and garden products, small stones and similar products. Typically, this bag is formed from polyolefin film material which may be comprised of one of high density, low density or linear low density polyethylene, polypropylene or mixtures thereof. The bag 10 of the present invention is adapted to contain loads of from about 25 lbs to 40 lbs or more of granular products of the above-mentioned type. The bag when fabricated to contain about 40 lbs of granular products, typically has a width of approximately 15 inches and a length of approximately 24 inches.

The heavy-duty plastic bag 10 is conveniently formed from such film material in tubular form and as herein illustrated it defines a front wall 12, a rear wall 13 and integrally formed opposed side edges 14 which are formed by the tubular extruded film when flattened to form juxtaposed front and rear walls 12 and 13. The top edge 16 of this tubular film is sealed by a heat sealing strip 17 extending parallel to the top edge. A plastic molded handle 18 is ultrasonically welded along the top edge as shown in its lower portion 19 which extends over the heat sealing strip. A loose skirt portion 20 remains above the heat sealing strip 17 between the front and rear walls 12 and 13 to the top edge 16 of the bag. It is pointed out that the bag can also be formed differently with side edge seals, as is obvious to a person skilled in the art.

A pouring spout 25 is defined in a top corner of the bag by a detachable corner portion 25′ delineated by a perforated tear line profile 26 formed in juxtaposition in the front and rear walls 12 and 13. The tear line profile 26 is better illustrated in FIG. 2.

As shown in FIG. 2, this tear line profile 26 is defined by a first straight line segment 27 which extends downwardly from the top edge 16 of the front and rear walls of the bag and angulate at an angle with respect to the top edge in the direction of a near one of the opposed side edges, herein side edge 14. The first straight line segment 27 extends at an angle of about 75° with respect to the top edge 17. The first straight, line segment 27 also merges into a concavely curved transition segment 28 to connect to a second straight line segment 29 extending downwardly from the transition segment 28 at an angle of about 71° with respect to the side edge 14 and terminates at this side edge.

The perforated tear line 26 is formed by a constant and equal cut-to-uncut perforation ratio which is not precisely illustrated in the drawings due to the size of the Figures but this ratio is 3.5 mm/3.5 mm. It is also pointed out that the concavely curved transition segment 28 has a length which is approximately 15% and more precisely 15.6% of the total length of the perforated tear line profile 26. Such constant perforation ratio and the angle of the transition segment 28 being set and about 124°, provides a substantially constant resistance along the entire tear line profile making it easy for a user person to detach the corner portion 25′ from the bag. Because the straight line segments are angulated in the same direction, as well as the transition segment, the corner portion 25′ is easy to tear off. It does not present resistance along its profile and provides a larger opening than prior art bags of the same type.

It is also pointed out that the tear line profile is provided with a slit 30 which extends through both the front wall 12 and rear wall 13 in the skirt portion 20. During the manufacturing of the bag this slit may extend into the heat sealing strip but it is pointed out that the cut-to-uncut ratio of the tear line profile is sufficient to prevent the corner portion from being detached when the bag is subjected to the drop tests, as previously described, even if the seal line is cut by a perforation. As shown in FIG. 2, the first straight line portion 26 extends to the top edge 17 of the bag a distance of about 4 inches from the side edge 14. The second straight line segment terminates at the side edge 14 a distance of about 4.5 inches from the heat sealing strip 17. The first straight line segment 26 has a length of 3.05 inches and the second straight line segment 29 has a length of 2.70 inches. The transition segment has a length of 1.06 inches.

An important feature of the pouring spout design or the tear line profile configuration of the pouring spout is that it provides an improved pour time for dispensing the granular product, herein salt pellets, from such bags. This is a major improvement over prior art bags as previously referred to. Tests have proven that the pour time of the bag of the present invention is 30% faster than the known prior art bags. Although a one second improvement in pour time for such a bag may sound like a small difference, it constitutes a very important difference to a person holding a 40 lbs bag at chest height particularly with weak or aching muscles, when time seems to stretch out. Therefore it is considered to be a real advantage for elderly people or people not in perfect physical condition or for the female gender which are not as strong as the male gender. Considering the aging population in North America and an increasing number of people handling these bags due to increasing concerns in water quality, there is a real need to improve these bags to make them easy to use and safe. As shown in FIG. 4, the handle 18 also helps in supporting the bag and guides the spout opening 25. The hand of the user holding the handle does not interfere with the bag side walls and the product therein.

Following are tests which show the improvement in pour time between the bag of the present invention and a similar bag constructed in accordance with the prior art wherein the spout is formed by an arcuate perforated profile. The prior art bag in Table 1 is identified as the “Control Sample” and the bag of the present invention is identified as “Design E4.5”:

TABLE 1

Time to Empty Bag(s)

Sample Number
Control Sample
Design E 4.5

1
6.64
4.45

2
5.90
3.72

3
5.20
3.99

4
5.40
4.79

5
4.91
4.06

6
4.95
4.07

7
4.89
3.66

8
5.35
3.91

9
5.70
3.29

10
4.27
3.49

11
4.5
4.15

12
4.74
3.45

13
4.70
3.42

14
4.64
3.79

15
3.81
2.77

16
1.24
3.06

17
4.41
2.91

18
4.12
3.36

19
3.99
3.32

20
3.83
3.02

21
3.72
3.38

22
3.82
3.42

23
3.95
2.87

24
3.89
3.16

25
3.59
2.59

Average
4.61
3.52

Std Dev
0.77
0.54

Maximum
6.64
4.79

Minimum
3.59
2.59

Range
3.05
2.20

Time Difference
1.08
31%

Table 2 shows the variance of the perforations of the two bag types, in the “x” and “y” axis, that is along the sealing strip 17 and the near edge 14 (namely of the 4 inch length and 4.50 inch length). Twenty-five bags are formed in accordance with the prior art and twenty-five are formed in accordance with the tear line profile of the present invention. The test conditions were as follows. The bags were poured into a bin with an opening and height similar to a water softener tank. The height of the tank opening was 1067 mm. The test results were recorded by an independent person. Another person emptied the water softener salt into the water tank by lifting the corner with the easy open perforation to roughly 1 cm above the water tank. Then the bag was tilted so that the closed end was elevated roughly 20° higher than the spout open end, which faced the water tank opening. While the bags were emptying, the closed bag end was raised to a roughly 85° elevation compared to the spout open end. For each test series a new batch of salt was used. Time taking started as the bag started to empty and ended after the last salt pellet had left the bag.

TABLE 2

Size Variance of Regular Production Bags

Sample
Control
Control
Design
Design

Number
Sample X
Sample Y
E 4.5X
E 4.5Y

1
103
100
104
116

2
103
103
106
121

3
104
100
105
120

4
103
103
104
114

5
102
100
106
122

6
107
103
109
118

7
102
102
105
123

8
107
100
104
117

9
103
103
105
120

10
107
100
106
121

11
102
101
105
117

12
101
101
105
120

13
101
99
104
116

14
102
102
104
117

15
102
102
106
121

16
107
99
105
120

17
102
102
105
120

18
103
102
105
118

19
102
99
106
118

20
102
102
106
119

21
101
101
105
116

22
103
101
107
119

23
102
102
107
120

24
102
98
104
111

25
103
102
106
117

Average
103.00
101.08
105.36
118.44

Std Dev
1.91
1.44
1.19
2.66

Maximum
107.00
103.00
109.00
123.00

Minimum
101
98.00
104.00
111.00

Range
6.00
5.00
5.00
12.00

It is to be noted that the pour time, as demonstrated through several test series, is a direct function of the size of the spout opening and the pattern in which the salt stored in the bag previous to being poured into the water softener tank. However, the influence of the pattern in which the salt was stored previous to being poured into the water softener tank decreases as the opening in the bag becomes larger. This is because the flow of the salt out of the bag opening is similar as the turbulent flow of a fluid out of an orifice. This flow becomes increasingly laminar and therefore faster the larger the orifice is. Another factor influencing the pour time is the size of the salt pellets. As for each series of bags one batch of salt was used.

Referring now to FIG. 4, there is shown the configuration of the perforating blade 35 which is used to form the perforated tear line 26. This blade 35 is formed of any material having the requisite strength and sharpness to form the perforations 26′ as above described. Such a perforation blade 35 may be formed of stainless steel, carbon steel and other convenient material. The blade 35 has a plurality of spaced-apart teeth 36 which are spaced apart an equal distance from one another and mounted into the die assembly 40, as shown in FIG. 5, which projects the blade teeth a predetermined distance into the folded film material whereby the teeth 36 will form slits and spaces therebetween which are of equal length. At the end of the blade 35 there is provided a slit forming section 37 which has a plurality of smaller slit forming teeth 38 which are sized to provide the slit 30 in the skirt 20 of the bag. Such knife blade designs are, for example, described in our earlier U.S. Pat. No. 5,636,925.

As shown in FIG. 5, the knife blade 35 is mounted in the die assembly 40 and more particularly in the blade holder 41 thereof. A top frame 42 is secured over the blade holder 41 in perfect alignment therewith by a pair of shoulder bolts 43. A linear bearing 44 is provided in the top frame 42 and through which the shoulder bolts extend. The entire assembly of the blade holder and top frame is reciprocated at high speed by a cylinder 45 onto a bottom sprung support 46. Such die assembly is also well known in the art and similar to the one described in our previously referred to U.S. Pat. No. 5,636,925.

FIG. 6 illustrates the relationship between the blade holder 41 and the bottom sprung support 46 and shows the delineated configuration of the tear line profile by the shape of the blade support 41′. This blade support is provided with a slot 47 in which the knife blade 35 is inserted and secured. This die assembly is caused to reciprocate as the folded plastic film tube which forms the bag 10 of the present invention is displaced between the blade holder and the bottom sprung support. The operation of this die assembly is also well known in the art and forms part of the prior art.

It is pointed out that the bag, when manufactured, resembles the bag as shown in FIG. 1 wherein the bottom end 21 of the bag is unsealed. The granular product is dispensed in the bag from this bottom end with the bag being upside down. After the bag is filled a heat seal 22, as shown in FIG. 3, is formed to seal the bag.

It is within the ambit of the present invention to cover any obvious modifications over the preferred embodiments described herein, provided such modifications fall within the scope of the appended claims.

Claims

1. A heavy-duty plastic bag adapted to contain a granular product; said bag having a front and rear wall, an open bottom edge adapted to be sealed after the granular product is dispensed in the bag, a heat sealing strip spaced adjacent a top edge of said bag and forming a skirt portion between said heat sealing strip and said top edge, a pouring spout is defined in a top corner of said bag by a detachable corner portion delineated by a perforated tear line profile formed in juxtaposition in said front and rear walls, said tear line profile defining a first straight line segment extending downwardly from said top edge of said front and rear walls and angulated at an angle with respect to said top edge in the direction of a near one of opposed side edges of said bag, said first straight line segment merging into a concavely curved transition segment to connect to a second straight line segment extending downwardly from said transition segment at an angle with respect to said near one of said opposed side edges and terminating at said near one of said side edges, said concavely curved transition segment having a length which is approximately 15% (fifteen percent) of the total length of said perforated tear line profile; said perforated tear line profile further terminating at said top edge in a slit extending through said skirt portion between said top edge and said heat sealing strip.
2. A heavy-duty plastic bag as claimed in claim 1, wherein said bag is formed from tubular extruded film, said top edge of said bag being an open top edge with said heat sealing strip interconnecting said front and rear walls together adjacent said top end.
3. A heavy-duty plastic bag as claimed in claim 1, wherein said cut to uncut perforation ration is 3.5 mm/3.5 mm.
4. A heavy-duty plastic bag as claimed in claim 1, wherein said heavy-duty plastic bag has a carrying capacity of between about 25 pounds to at least 40 pounds of said granular product, said first straight line segment extending from said top edge a distance of about 4 inches from said near one of said opposed side edges and said second straight line segment terminating at said near one of said opposed side edges a distance of about 4.5 inches from said heat sealing strip.
5. A heavy-duty plastic bag as claimed in claim 4, wherein said first straight line segment has a length of 3.05 inches, said second straight line segment having a length of 2.70 inches, and said transition segment having a length of 1.06 inches.
6. A heavy-duty plastic bag as claimed in claim 5, wherein said concavely curved transition segment has a length which is 15.6% of said total length of said perforated tear line profile.
7. A heavy-duty plastic bag as claimed in claim 5, wherein said angle of said first straight line segment is 75° (degrees), said angle of said second straight line segment is 71°, said transition segment forming an internal angle of 124° between said first and second straight line segments.
8. A heavy-duty plastic bag as claimed in claim 1, wherein a carrying handle is secured along said top end of said bag, said handle providing gripping support for handling said bag during transport and pouring of granular product with said detachable corner portion torn off at said perforated tear line.
9. A heavy-duty plastic bag as claimed in claim 7, wherein said front and rear walls of said plastic bag each have a thickness of between approximately 4 to 8 mils, said front and rear walls being made of polyolefin film comprised of one of high density, low density, linear low density polyethylene, polypropylene, said bag having a width of approximately 15 inches and a length of approximately 24 inches with a capacity to hold at least 40 lbs of the granular product.
10. A heavy-duty plastic bag as claimed in claim 8, wherein the granular product is salt pellets, said salt pellets being completely evacuated from said bag through said pouring opening with a pour time of approximately 3.5 seconds.

Priority Claims (1)

Number	Date	Country	Kind
2,629,002	Apr 2008	CA	national

Heavy-duty plastic bag with easy tear corner spout portion

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Priority Claims (1)