US20120224793A1

US20120224793A1 - Polymeric bag with elastic drawtape

Info

Publication number: US20120224793A1
Application number: US13/247,560
Authority: US
Inventors: Matthew Kim; Gary Price; John Woelfle
Original assignee: Trans Western Polymers Inc
Current assignee: Trans Western Polymers Inc
Priority date: 2011-03-04
Filing date: 2011-09-28
Publication date: 2012-09-06

Abstract

A manufacturing method for producing a plurality of polymeric drawtape bags, the method including: a) dispensing a film of polymeric pliable material; b) producing a web of folded and sealed polymeric panels from the film, the web including a plurality of polymeric bags having a pair of drawtapes added into a pair of hems proximate a bag opening with a series of notches produced near lateral edges of each of the hems exposing the drawtapes with a series of lateral seals applied to the exposed drawtapes within the notches; c) measuring a relative placement of the series of notches with respect to the seals; and d) providing feedback to a notch production system to improve placement of the series of lateral seals of the exposed drawtapes within the notches by accurately locating the series of notches produced along the web.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/449,591, filed 4 Mar. 2011, the contents of which are hereby expressly incorporated in its entirety by reference thereto for all purposes.

BACKGROUND OF THE INVENTION

The present invention relates generally to polymeric bags, and more specifically, but not exclusively, to polymeric elastic drawtape trash bags and methods of their manufacture.
Polymeric trash bags are a common household product and have been so for many years. Common trash bags include a variety of polymeric materials, sizes, thicknesses, colors, counts, and closure formats. Polymeric trash bags are used not only for collection, containment, and disposal of trash and garbage, but also for long term storage of items such as clothing and the like. With the constant growing use of polymeric trash bags, manufacturers are always researching new manufacturing materials and methods to enhance consumer experience while at the same time providing options to generate less waste, enhance sustainability, and improve profitability.
The closure method of polymeric trash bags differ in design. A common polymeric bag design can be as simple two bag panels sealed along opposing sides creating what is commonly called an ‘open top’ bag. This style of bag is inserted into a trash container with the upper edges of the bag rolled over the container rim to provide a means to hold the bag to the container. When the bag is filled, the bag is removed by pulling the bag from the trash container, spinning the top of the bag shut, and then applying a twist-tie (or other closure system) to hold the bag shut. Two specific inherent frustrations apply to this design: (1) The bags tend to fall into the trash container while filling as the bag does not provide a feature to secure the bag to the top of the container; and (2) Consumers have expressed concern that the tie devise sometimes become lost thus requiring the consumer to (try to) tie a knot in the bag which can be difficult in the event there is not enough material remaining in the bag body once filled.
To overcome the ‘open top’ bag closure frustrations, manufacturers developed a polymeric trash bag commonly called “drawtape” and/or “drawstring” trash bags. A typical drawtape (or drawstring) bag feature includes a pair of polymeric strips enclosed in a formed hem in the top of each bag panel. When polymeric drawtape trash bags are used by a consumer, the drawtape feature provides a method for removal of the trash bag from the container as the drawtape acts as a handle for gripping and lifting the bag. Once the bag has been lifted from the container, the polymeric drawtape strips can be tied to each other to secure the bag shut and then provide a carrying mechanism to transport the bag to its desired location. Throughout the existence of drawtape style polymeric trash bags, this design style has become a common product used in households and business.
Because of the variety of polymeric drawtape trash bag sizes and trash container sizes, a common unsatisfactory experience expressed by consumers when using a polymeric drawtape trash bag in a container is the bags do not always remain secured to the top of the container consequently when the bag is filled, the bag tends to pull/drop inward into the container which then results in trash and garbage not completely being captured by the bag thus the trash container is subject to becoming soiled and unsanitary. When this condition occurs, the consumer has to reach into the container and through trash to locate the top of the trash bag—more specifically locate and grip the drawtape pull feature. When the bag fails to remain in place, the outcome defeats the purpose of using a bag to provide a barrier between the trash and trash container.
Consumers are always seeking the latest and greatest feature to enhance a product experience. With this in mind, manufacturers began researching new materials and methods that offer stretchable drawtape strips in trash bags. The advantage of a stretchable drawtape is simple—when the top section of a polymeric drawtape trash bag is folded over the container rim, the bag tends to stay in place thus allowing the bag panels to act as a liner overcoming the need for consumers having to reach into a trash container to reattach the bag to the container rim and having to clean the container interior.
Elastic drawtape polymeric trash bags are manufactured by several companies all of which utilize a variety of manufacturing techniques, methods, materials, and processes. Following are two product description examples and corresponding consumer experiences.
1. One product design utilizes an elastic polymeric drawtape enclosed in individual hems along the top of the polymeric trash bag. A dedicated heat seal attaches the drawtape ends to the bag hem panels on each side of the bag. The dedicated drawtape seals extend further into the bag body panel width than the main bag panel seals thus creating a reduced bag opening size (circumference) when measured against the bag panel interior size (circumference). This reduced opening provides a means to secure the bag to a container rim. This bag design includes a centralized semicircular cutout in the top of the bag to allow bag closure when the drawtape strips are pulled through the cutouts. A descriptive reference for this product is found in US Pub No. 2010/0111452-A1 entitled REDUCED OPENING ELASTIC DRAWSTRING BAG filed 30 Oct. 2008.
This product design requires the consumer to stretch the upper portion of the bag body hem panels while in the same motion stretching the elastic drawtape strips in order to secure the top of the bag around the container rim. Stretching both the bag body hem panels and elastic drawtape in one motion requires additional pulling force and strength from the consumer when compared to product #2 described in the next section below. Furthermore, when having to pull the drawtape strips from a centralized hole, the experience can lead to cinching/gathering of the bag hem panels upon closure thus making it difficult to fully close the bag. Depending on the consumer, products that require an extra force to use a trash bag may lead to frustration and tendency to purchase other products.
2. One product design utilizes a polymeric drawtape material that is not of an elastic material in design however the drawtape strips have been designed in a manner to include looped sections which have an elastic adhesive strip attached to the looped sections. The elastic adhesive strips are adhered to the polymeric drawtape strips to allow the drawtape to react in an elastic manner when pulled. There is one drawtape strip enclosed in each of the two individual bag body hems along the top of the polymeric bag. In this design, the bag has a pair of notch cutouts on the top of the bag with one located on each side of the bag. The drawtape is sealed to each other (strip 1 to strip 2) while remaining separate of being sealed to the bag body panels and hem sections. The notch cutouts allow the drawtape to extend outside of the bag body panels. This design requires less force when the drawtape is pulled by the consumer as the consumer only has to stretch the drawtape strips around the container rim to secure the bag to the container. A descriptive reference for this product is found in U.S. Pat. No. 6,059,458 entitled ELASTIC TOP DRAWTAPE BAG AND METHOD OF MANUFACTURING THE SAME filed 5 Feb. 1999.
Depending on the consumer and pulling force exerted during closure, the adhesive strips on the looped drawtape can break free from the non-elastic drawtape strips thus rendering the stretchable capability unusable. Furthermore, it was discovered during visual product analysis that the notch proximity to the edge of the bag panels varied in dimension and the shape was of a rectangular shape vs. a half semicircular shape as noted in the aforementioned patent document drawings. Depending on the pulling force exerted on the bag during closure, the notches tend to enlarge thus creating openings at the drawtape closure points which could subject the bag contents to pests and other environmental conditions.
What is needed is an improved design and manufacturing method for polymeric elastic drawtape bags that addresses the limitations of existing bags.

BRIEF SUMMARY OF THE INVENTION

Disclosed is an improved design and manufacturing method for polymeric elastic drawtape bags that addresses the limitations of existing bags. The following summary of the invention is provided to facilitate an understanding of some of technical features related to polymeric bags and manufacturing processes thereof, and is not intended to be a full description of the present invention. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
A drawtape bag includes a body having a pair of pliable opposing polymeric body panels joined together with a pair of lateral body seals along a pair of opposing lateral sides and a bottom bridging and closing the pair of pliable opposing polymeric body panels producing a polymeric bag with an open mouth end at a top end, the body panels each forming a hem extending along the open mouth end, each the hem including a pair of lateral notches at the opposing lateral sides; and a pair of pliable polymeric elastomeric drawtapes moveably disposed without attachment within the hems, one drawtape within each hem wherein opposing lateral sides of the pair of drawtapes are exposed within the notches and joined together with a pair of lateral drawtape seals to form a single closed drawtape loop extending around a perimeter of the open mouth end wherein the single closed drawtape loop is configured to be drawn through one or both of the pair of lateral notches to close the open mouth end; wherein the lateral notch has a length in a direction along the hem about 1.625 inches or less wherein the body has a width about 24 inches or less and a length about 27 inches or greater.
A method of manufacturing a drawtape bag includes a) directing a pair of overlying polymeric film panels in a machine direction wherein the pair of polymeric film panels are joined together at a bottom edge and open at a top edge opposite of the bottom edge to form a single polymeric film, with the panels being separable from each other along a mouth end formed opposite the bottom edge; b) producing a pair of hems along the top edges of the film panels of the single polymeric film; c) producing drawtape notches in each hem of the pair of hems at regular distance intervals corresponding to a desired width of the drawtape bags; d) adding a pair of pliable polymeric drawtape into the pair of hems, a drawtape disposed into each hem; e) sealing the panels to each other using body seal structures generally transverse to the machine direction to create individual drawtape bags; and f) sealing the drawtapes to each other using drawtape seal structures within the drawtape notches to form, for the drawtape bag, a single closed drawtape loop disposed around a perimeter of the mouth end.
A manufacturing system for producing polymeric drawtape bags, the system including a plurality of manufacturing stations to dispense polymeric pliable material and to produce a web of folded and sealed polymeric panels forming a plurality of polymeric bags having a pair of drawtapes added into a pair of hems proximate a bag opening with a series of notches produced near lateral edges of each of the hems exposing the drawtapes with a series of lateral seals applied to the exposed drawtapes within the notches; and a notch registration system, coupled to one or more stations of the plurality of manufacturing stations, measuring a relative placement of the series of notches with respect to the seals and providing feedback to a notch production system of the plurality of manufacturing stations to improve placement of the series of lateral seals of the exposed drawtapes within the notches by accurately locating the series of notches produced along the web.
A manufacturing method for producing a plurality of polymeric drawtape bags, the method including: a) dispensing a film of polymeric pliable material; b) producing a web of folded and sealed polymeric panels from the film, the web including a plurality of polymeric bags having a pair of drawtapes added into a pair of hems proximate a bag opening with a series of notches produced near lateral edges of each of the hems exposing the drawtapes with a series of lateral seals applied to the exposed drawtapes within the notches; c) measuring a relative placement of the series of notches with respect to the seals; and d) providing feedback to a notch production system to improve placement of the series of lateral seals of the exposed drawtapes within the notches by accurately locating the series of notches produced along the web.
Although the production lines used to manufacture polymeric drawtape trash bags utilize industry standard technologies, the process has an inherent variation in the placement of the drawtape notch cutout. The variation is partially the result of the pliable characteristic of the film and web tension variables. One component of a bag manufacturing line is referred to as “The Dancer” (a downstream component) also contributes to notch placement variation as the Dancer tends to oscillate in response to film tension variables thus offsetting the notch placement. One feature of our invention includes technologies to control and limit the notch placement variations.
Other features, benefits, and advantages of the present invention will be apparent upon a review of the present disclosure, including the specification, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.

FIG. 1 illustrates a storage system including a receptacle and a polymeric bag sized for use with the receptacle;

FIG. 2 illustrates a front view of a first type of a polymeric drawtape bag;

FIG. 3 illustrates a front view of a second type of a polymeric drawtape bag;

FIG. 4 illustrates an overview of a manufacturing process producing the first type of polymeric drawtape bag;

FIG. 5 illustrates an overview of a manufacturing process producing the second type of polymeric drawtape bag; and

FIG. 6 illustrates an overview of the control components of the manufacturing process.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provide an improved design and manufacturing method for polymeric elastic drawtape bags that addresses the limitations of existing bags. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements.
FIG. 1 illustrates a storage system 100 including a receptacle 105 and a polymeric bag 110 sized for use with the receptacle. Storage system 100 is ubiquitous and implemented in a wide variety of formats. The present invention is most conveniently described in a specific context, but it is understood that it may be adapted for implementation in many other contexts as well.
The specific preferred context includes bag 110 as a nominally 13 gallon (49.21 liters) drawstring bag with “gripping” technology and having side hole notch for accessing the drawstring, hereafter referred to as a 13 gallon bag. A nominal 13 gallon bag is configured for receptacle 105 as a nominally 13 gallon receptacle, but there is a very wide variation in dimensions. For example, even though referred to as a 13 gallon receptacle, the actual gallon equivalent of receptacle 105 can range from about 9 gallons to about 14 gallons. Receptacle 105 may have representative dimensions ranging from a top rim circumference of about 46.5 inches to about 49 inches while a depth dimension varies in a range of about 19 inches to about 24 inches. For a limited sampling of receptacles, receptacle 105 is, on average, about 12.4 gallons with a circumference of about 48 inches and a depth of about 22 5/9 inches. Any sampling will show variation from these values.
Any manufacturer of bag 110 desirably provides dimensions for bag 110 that will provide usefulness to as great a number of people of possible, in as simple and efficient manner as possible. Ultimately for any particular implementation of manufacturing for bag 110, specific bag dimensions are chosen in contemplation of a range of useful receptacle sizes. For a “grip” feature, it is contemplated that the circumference of the gripper feature of bag 110 will be smaller than the smallest circumference of the set of receptacles, with elastic “stretching” to provide the grip. There is a limit to the amount of stretching that can occur before deformation destroys the elasticity, which defines an effectively upper bound for the circumference for receptacle 105. For a particular design of bag 110, the present invention is used to improve the usefulness to the end-user.
FIG. 2 illustrates a front view of a first type of a polymeric drawtape bag 200. Bag 200 includes a polymeric film 205 with a first fold 210 at a bottom and a pair of lateral edge seals 215 to produce an opening 220 at a top. At the top a pair of second folds 225 and a pair of top seals 230 create a pair of hems 235 enclosing a pair of drawtapes 240 that are sealed together at a pair of lateral edge seals 245 to produce a single closed loop 250 extending through both hems 235. Loop 250 is captured within hems 235, but is otherwise unattached to polymeric film 205 so loop 250 moves independently and freely within hems 235. A set of lateral notches 255 in hems 235 expose lateral edge seals 245 of loop 250.
Several important aspects of the present invention relate to the dimensions of the bag, the seals, the notches and the interplay of these dimensions in the context of use with receptacle 105 shown in FIG. 1. As noted above, dimensions of notches 255 affect the size of “holes” in the top of bag 200 after loop 250 is pulled closed and tied. Notches 255 are used to allow a user to conveniently access loop 250 and to remove bag 200 from receptacle 105 so they are necessary but can, when not appropriately addressed, produce such undesirable effects. Heretofore Applicant is unaware that bag manufacturers have manufactured an apparatus such as bag 200, much less addressed specifically problems associated with enlargement of lateral notches 255 in bag 200.
Specifics of bag manufacture vary from one bag format to another. As noted, there are different ways of providing a reduced circumference opening, not all of which include an independent closed loop drawtape accessed by lateral notches with the closed loop drawtape providing the sole gripping function. Important dimensions for bag 200 include Bag_Width1and Bag_Length1which define the useful capacity of bag 200. Lateral side seals 215 each have a width shown as Body_Seal1defining a width of the bag opening therebetween. Lateral edge seals 245 each have a width shown as Loop_Seal1defining a width, Loop_Length1, therebetween. Notches 255 have a nominal length dimension shown as Notch_Length1. Loop_Seal1is greater than Body_Seal1and as explained in more detail herein, Notch_Length1is a factor related to Bag_Width1and is desirably reduced when possible, while preserving other important characteristics of bag 200.
FIG. 3 illustrates a front view of a second type of polymeric drawtape bag 300. Bag 300 includes a polymeric film 305 with a first fold 310 at a bottom and a pair of lateral edge seals 315 to produce an opening 320 at a top. At the top a pair of second folds 325 and a pair of top seals 330 create a pair of hems 335 enclosing a pair of drawtapes 340 that are sealed together at a pair of lateral edge seals 345 to produce a single closed loop 350 extending through both hems 335. Loop 350 is captured within hems 335, but is otherwise unattached to polymeric film 305 so loop 350 moves independently and freely within hems 335. A set of lateral notches 355 in hems 335 expose lateral edge seals 345 of loop 350.
Several important aspects of the present invention relate to the dimensions of the bag, the seals, the notches and the interplay of these dimensions in the context of use with receptacle 105 shown in FIG. 1. As noted above, dimensions of notches 355 affect the size of “holes” in the top of bag 300 after loop 350 is pulled closed and tied. Notches 355 are used to allow a user to conveniently access loop 350 and to remove bag 300 from receptacle 105 so they are necessary but can, when not appropriately addressed, produce such undesirable effects. Heretofore Applicant is unaware that bag manufacturers have manufactured a drawtape bag such as bag 300, much less addressed specifically problems associated with enlargement of lateral notches 355 in bag 300.
Specifics of bag manufacture vary from one bag format to another. As noted, there are different ways of providing a reduced circumference opening, not all of which include an independent closed loop drawtape accessed by lateral notches with the closed loop drawtape providing the sole gripping function. Important dimensions for bag 300 include Bag_Width2and Bag_Length2which define the useful capacity of bag 300. Lateral side seals 315 each have a width shown as Body_Seal2defining a width of the bag opening therebetween. Lateral edge seals 245 each have a width shown as Loop_Seal2defining a width, Loop_Length2, therebetween. Notches 255 have a nominal length dimension shown as Notch_Length2. Loop_Seal2is equal to Body_Seal2with Bag_Width2less than Bag_Width1and Bag_Length2greater than Bag_Length1(to make the capacity of the bag 300 essentially the same as bag 200), Notch_Length2is less than Notch_Length1, and as explained in more detail herein, Notch_Length2is a factor related to Bag_Width2and is desirably reduced when possible, while preserving other important characteristics of bag 300.
For example, Notch_Length1is at least about 1.625 inches (and may be increased in some implementations if variation in notch cutting risks having a lateral edge seal 345 sealed to hems 335). Loop_Seal1is about 0.625 inches greater than Body_Seal1. For other bag designs having lateral cutouts accessing an enclosed elastic-type drawstring, notch lengths are significantly larger and can be about 2.25 inches to about 2.5 inches. As further discussed below, use of a novel manufacturing process enables the notch length to be reduced. For example, Notch_Length2is about 1 inch, with Loop_Seal2about equal to Body_Seal2.
FIG. 4 illustrates an overview of a manufacturing process 400 producing the first type of polymeric drawtape bag 200 shown in FIG. 2. Process 400 includes three manufacturing stations, a dispensing station 405, a first forming station 410, and a second forming station 415. Station 405 holds a roll 420 of polymeric pliable material (aka polymeric film) 425. Roll 420 is manufactured in a blown film extrusion process in the shape of a tube that is flattened into a web format, then cut on one side and then wound into a finished roll 420. Film 425 drawn off roll 420 includes a fold 430 at a bottom edge while a top edge is open, which creates a front panel (shown) and a back panel (not shown). Station 405 delivers film 425 to station 410 and then to station 415 for further processing.
Station 410 pulls film 425 over a set of folding plates where a section of both the front and back film panels at the top end are each folded back over a pair of elastomeric (e.g., formed of a polymeric material to be elastic for expanding, gripping receptacle openings to hold bag upright) drawtapes 432. A top seal 435 is applied to both the front and the back film panels to form a pair of hems 440 and the bag opening therebetween (only the front drawtape 432, seal 435, and hem 440 are shown for clarity). Specifically, a cutter (aka—Servo Cutter or the like) periodically cuts a pair of notches 445, one notch 445 into each panel, to expose periodic openings in the top edge. Film 425 continues downstream over a set of folding bars where the individual front and back bag are separated and hem 440 is then formed respectively in each panel. At this point, a single strip of polymeric elastic drawtape 432 is inserted into each hem 440 (a first strip inserted into a front hem 440 and at the same time a second strip inserted into a back hem 440). Film 425 continues downstream where the respective top seals 435 are applied to both the front and back panels, thus creating hems 440, one in each panel, with each hem 440 enclosing one polymeric elastic drawtape 432.
Film 425 continues from station 410 in this format downstream into station 415 for further processing. Film 425 travels through a web tensioning device (aka—a Dancer), and continues downstream around a sealing drum where periodic bag panel seals 450 and drawtape seals 455 are made. Seals 450 are made from primary seal bar mechanisms secured in the sealing drum. Seals 450 are made from seal bars that are secured to the primary seal bars however the sealing variables are controlled separate of the primary seal bar. Film 425 continues over a series of folding bars for folding the sealed film into a folded web format.
The folded web then travels through a perforation knife cutting station where periodic perforations 460 are made to folded web which provides a mechanism to separate the sealed web format into individual bags in a downstream machine (e.g., a folder, winder, or the like—not shown). Bag 200 may be thus made by process 400 and provides good results for a range of products. A controller 465 using a feedback system 470 is optional in process 400 for notch placement, but its use as further described herein could improve notch placement and permit narrower notches to be employed and thereby improving bag 200 by reducing the notch hole enlargement issue described herein.
Process 400 includes a considerable length of film 425 throughout the manufacturing line. For example, a distance between the Servo Cutter at station 410 and a web perforation device at a downstream end of station 415 is about fifty feet. This equates to about 25 bags thus any variation in a tension of film 425 tension typically results in oscillations in the Dancer which in turn creates an expansion or retraction of the web path in the machine direction. These oscillations cause the notch cutout placement to move proportionally to the web expansion/retraction. In the event the notch cutout 445 moves upstream or downstream as the result of the web movement, notch 445 may be positioned in the immediate area of the drawtape seal 450 thus becoming sealed to either end of hem 440 thus rendering the elastic characteristic of drawtape 432 to not function as designed. In order to provide a means of compensation for the web expansion/retraction and to ensure a precise placement of notch 445 and its registration to the bag panel side seals 450 and drawtape seal 450, controller 465 and feedback system 470 are used and the tighter these registration requirements (e.g., smaller notches), the more useful is controller 465 and feedback system 470. Thus, for process 500 described below in FIG. 5 for production of bag 300, the controller and feedback system are desirably included.
FIG. 5 illustrates an overview of manufacturing process 500 producing the second type of polymeric drawtape bag 300 shown in FIG. 3. As further described below, process 500 is similar to process 400 except that bag 300 is produced instead of bag 200. Thus process 500 makes a bag that is narrower, longer, and has a smaller notch, primarily by controlling registration better using a controller and a feedback system. Process 500 includes three manufacturing stations, a dispensing station 505, a first forming station 510, and a second forming station 515. Station 505 holds a roll 520 of polymeric pliable material (aka polymeric film) 525. Roll 520 is manufactured in a blown film extrusion process in the shape of a tube that is flattened into a web format, then cut on one side and then wound into a finished roll 520. Film 525 drawn off roll 520 includes a fold 530 at a bottom edge while a top edge is open, which creates a front panel (shown) and a back panel (not shown). Station 505 delivers film 525 to station 510 and then to station 515 for further processing.
Station 510 pulls film 525 over a set of folding plates where a section of both the front and back film panels at the top end are each folded back over a pair of drawtapes 532. A top seal 535 applied to both the front and back film panels to form a pair of hems 540 and the bag opening therebetween (only the front drawtape 532, seal 535, and hem 540 are shown for clarity). Specifically, a cutter (aka—Servo Cutter or the like) periodically cuts a pair of notches 545, one notch 545 into each panel, to expose periodic openings in the top edge. Film 525 continues downstream over a set of folding bars where the individual front and back bag are separated and hem 540 is then formed respectively in each panel. At this point, a single strip of polymeric elastic drawtape 532 is inserted into each hem 540 (a first strip inserted into a front hem 540 and at the same time a second strip inserted into a back hem 540). Film 525 continues downstream where the respective top seals 535 are applied to both the front and back panels, thus creating hems 540, one in each panel, with each hem 540 enclosing one polymeric elastic drawtape 532.
Film 525 continues from station 510 in this format downstream into station 515 for further processing. Film 525 travels through a web tensioning device (aka—a Dancer), and continues downstream around a sealing drum where periodic bag panel seals 550 and drawtape seals 555 are made. Seals 550 are made from primary seal bar mechanisms secured in the sealing drum. Seals 550 are made from seal bars that are secured to the primary seal bars however the sealing variables are controlled separate of the primary seal bar. Film 525 continues over a series of folding bars for folding the sealed film into a folded web format.
The folded web then travels through a perforation knife cutting station where periodic perforations 560 are made to folded web which provides a mechanism to separate the sealed web format into individual bags in a downstream machine (e.g., a folder, winder, or the like—not shown). Bag 300 may be thus made by process 500 and provides good results for a range of products just as is true for bag 200, with bag 300 providing a smaller notch-induced hole. A controller 565 using a feedback system 570 is preferred in process 500 for accurate notch placement to reduce notch length.
FIG. 6 illustrates an overview of a notch registration control system 600 useful in the manufacturing processes described herein, specifically as the “optional” components in process 400 and the “preferred” components in process 500. Of course a control system exists for processes 400 and 500 and the notch registration control system is an add-on (or integrated) function for a preferred system of achieving a goal of reduced notch length for any bag format using a manufacturing process generally similar to those described herein. Thus not all control and feedback systems and components used in processes 400 and 500 are described herein.
Control system 600 includes components that are preferably integrated into station 510 (and optionally station 410) and station 515 (and optionally into station 415) as shown. Components of control system 600 included in station 510 are an operator programmable interface 605, a web encoder 610, a servo controller 615, and a servo cutter motor 620. Interface 605 is used for the initial registration set point value as entered by an operator. Web encoder 610 generates a web speed feedback signal used at station 515. Servo controller 615 initiates a control sequencing of servo cutter motor 620. Servo cutter motor 620 actuates a notch cutter through the polymeric film as described herein.
Components of control system 600 included in station 515 include a motion controller 625, a dancer and roller assembly 630, and a dancer oscillation position feedback device 635. Dancer and roller assembly 630 provide real-time feedback of motion of the film as it travels through the stations of process 500. Rotary oscillations of dancer and roller assembly 630 are converted into linear oscillations by dancer oscillation position feedback device 635 and then into a dancer oscillation signal. Motion controller 625 is a central coordination point for process and feedback communication regarding notch registration. Motion controller 625 receives the web speed signal from web encoder 610 and the dancer oscillation signal from dancer oscillation position feedback device 635. Additionally, there is a notch registration feedback signal indicating current downstream notch registration as described below.
The notch registration feedback signal is obtained from capturing a parameter of the film as it relates to where the system is placing the notch in relation to the body and loop seals. Preferably system 600 uses a vision capture system at a vision capture point between two bags downstream of station 515. Preferably this vision capture point is a distance between a bag perforation 560 and a vertical trailing edge 640 of each notch cutout 545. This vision capture point is the same point on each bag during line operation.
System 600 includes, for a vision system, an imager 645 (e.g., feedback system 570) and a vision feedback processor 650 (e.g., controller 565). Imager 645 includes a digital capture imaging sensor that inspects a placement of edge 640 with respect to perforation 560. Imager 645 works in cooperation with feedback processor 650 to send a notch registration feedback signal to motion controller 625 so motion controller 625 can set precise registration of notch 545.
Description of Systems Control:
Upon start-up of the manufacturing line, an initial notch registration offset is set by a programmed value entered into interface 605 by an operator as determined by a visual measurement of a placement of notch 545 and its relation to perforation 560. During line operation, a trigger signal is generated from the bag machine perforation drum and is relayed to motion controller 625. Motion controller 625 uses feedback from three interface sources: web encoder 610 that measures web speed, feedback processor 650 providing the notch registration feedback signal based on a pixel count of stored images against a live image capture from imager 645 during operation, and dancer oscillation position feedback device 635. As the line continues to run, motion controller 625 calculates notch registration adjustments based on real time feedback from the web encoder, vision and dancer feedback systems. Motion controller 625 maintains registration by outputting a signal to servo controller 615 at every sequence of the perforation drum.
The improved manufacturing process can be implemented under program control of a plurality of machine code instructions accessed from a memory and executed by a controller or processor. Some or all of the inventive aspects of certain ones of the embodiments of the present invention may be implemented in such non-transitory program instructions stored in a memory.
As noted herein, the system and process are most preferably implemented in a polymeric bag used for collection and storage of materials. The system and methods above has been described in general terms as an aid to understanding details of preferred embodiments of the present invention. Other preferred embodiments of the present include the described application for improved polymeric trash bags. In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the present invention. The preferred embodiments include specific physical processing devices and steps, such as cutters for notches and inserters for placing drawtapes into formed hems. The preferred invention encompasses other devices and methods for producing notches, e.g., punches, lasers, and other processing equipment and methods, to yield the desired structures.
One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the present invention.
Reference throughout this specification to “one embodiment”, “an embodiment”, or “a specific embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention and not necessarily in all embodiments. Thus, respective appearances of the phrases “in one embodiment”, “in an embodiment”, or “in a specific embodiment” in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments of the present invention described and illustrated herein are possible in light of the teachings herein and are to be considered as part of the spirit and scope of the present invention.
It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application.
Additionally, any signal arrows in the drawings/Figures should be considered only as exemplary, and not limiting, unless otherwise specifically noted. Furthermore, the term “or” as used herein is generally intended to mean “and/or” unless otherwise indicated. Combinations of components or steps will also be considered as being noted, where terminology is foreseen as rendering the ability to separate or combine is unclear.
As used in the description herein and throughout the claims that follow, “a”, “an”, and “the” includes plural references unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The foregoing description of illustrated embodiments of the present invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention.
Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Thus, the scope of the invention is to be determined solely by the appended claims.

Claims

1. A drawtape bag comprising:

a body including a pair of pliable opposing polymeric body panels joined together with a pair of lateral body seals along a pair of opposing lateral sides and a bottom bridging and closing said pair of pliable opposing polymeric body panels producing a polymeric bag with an open mouth end at a top end, said body panels each forming a hem extending along said open mouth end, each said hem including a pair of lateral notches at said opposing lateral sides; and

a pair of pliable polymeric elastomeric drawtapes moveably disposed without attachment within said hems, one drawtape within each hem wherein opposing lateral sides of said pair of drawtapes are exposed within said notches and joined together with a pair of lateral drawtape seals to form a single closed drawtape loop extending around a perimeter of said open mouth end wherein said single closed drawtape loop is configured to be drawn through one or both of said pair of lateral notches to close said open mouth end;

wherein said lateral notch has a length in a direction along said hem about 1.625 inches or less wherein said body has a width about 24 inches or less and a length about 27 inches or greater.

2. The drawtape bag of claim 1 wherein a drawtape seal width of said lateral drawtape seal is greater than a lateral body seal width of said lateral body seal.

3. The drawtape bag of claim 2 wherein said drawtape seal width, as measured as a distance extending into said body from a lateral edge, is at least 0.5 inches greater than said lateral body seal width.

4. A drawtape bag comprising:

wherein said lateral notch has a length in a direction along said hem about 1 inch or less wherein said body has a width about 23 inches or less and a length about 28.25 inches or greater.

5. The drawtape bag of claim 4 wherein a lateral drawtape seal width of said lateral drawtape seal is about equal to a lateral body seal width of said lateral body seal.

6. The drawtape bag of claim 5 wherein said seals are about 0.125 inches wide.

7. A method of manufacturing a drawtape bag, comprising the steps of:

a) directing a pair of overlying polymeric film panels in a machine direction wherein said pair of polymeric film panels are joined together at a bottom edge and open at a top edge opposite of said bottom edge to form a single polymeric film, with the panels being separable from each other along a mouth end formed opposite the bottom edge;

b) producing a pair of hems along said top edges of said film panels of said single polymeric film;

c) producing drawtape notches in each hem of said pair of hems at regular distance intervals corresponding to a desired width of the drawtape bags;

d) adding a pair of pliable polymeric drawtape into said pair of hems, a drawtape disposed into each hem;

e) sealing said panels to each other using body seal structures generally transverse to the machine direction to create individual drawtape bags; and

f) sealing said drawtapes to each other using drawtape seal structures within said drawtape notches to form, for the drawtape bag, a single closed drawtape loop disposed around a perimeter of said mouth end.

8. The method of claim 7 wherein said drawtape seal structures are wider than said body seal structures.

9. The method of claim 7 wherein said drawtape seal structures are about equal to said body seal structures.

10. The method of claim 7 further comprising the steps of:

g) perforating each said seal structure generally transverse to said machine direction to define the drawtape bag between successive perforations.

11. The method of claim 10 further comprising the steps of:

i) imaging said successive perforations in relation to a trailing edge of associated successive drawtape notches to provide a series of notch registration signals; and

j) adjusting said forming step c) responsive to said series of notch registration signals.

12. A manufacturing system for producing polymeric drawtape bags, the system comprising:

a plurality of manufacturing stations to dispense polymeric pliable material and to produce a web of folded and sealed polymeric panels forming a plurality of polymeric bags having a pair of drawtapes added into a pair of hems proximate a bag opening with a series of notches produced near lateral edges of each of said hems exposing said drawtapes with a series of lateral seals applied to said exposed drawtapes within said notches; and

a notch registration system, coupled to one or more stations of said plurality of manufacturing stations, measuring a relative placement of said series of notches with respect to said seals and providing feedback to a notch production system of said plurality of manufacturing stations to improve placement of said series of lateral seals of said exposed drawtapes within said notches by accurately locating said series of notches produced along said web.

13. A manufacturing method for producing a plurality of polymeric drawtape bags, the method comprising the steps of:

a) dispensing a film of polymeric pliable material;

b) producing a web of folded and sealed polymeric panels from said film, said web including a plurality of polymeric bags having a pair of drawtapes added into a pair of hems proximate a bag opening with a series of notches produced near lateral edges of each of said hems exposing said drawtapes with a series of lateral seals applied to said exposed drawtapes within said notches;

c) measuring a relative placement of said series of notches with respect to said seals; and

d) providing feedback to a notch production system to improve placement of said series of lateral seals of said exposed drawtapes within said notches by accurately locating said series of notches produced along said web.