Patent Application
20230031779
Thermoplastic films are a common component in various commercial and consumer bags. For example, grocery bags, trash bags, drawtapes for bags, sacks, and packaging materials are commonly made from thermoplastic films. Such bags often include one or more features that improve the quality and/or functioning of the bag. For example, many bags include a hem formed and a drawtape within the hem. The drawtape enables a user to secure the contents of the bag by pulling the drawtape partially out of the hem to cinch the bag closed.
In some cases, drawtapes of bags are refined via a deformation process that modifies a property of the drawtape, such as its tensile strength, tear resistance, impact resistance, or elasticity. For example, a drawtape can be deformed to provide or improve upon elasticity so that the drawtape can more easily be stretched around the rim of a bin in which the bag is placed and to further enable the bag to grip the rim of the bin once placed inside. These deformation processes often create a plurality of ribs in the drawtape. To illustrate, a structural elastic-like film (SELF) process can deform a drawtape to include a plurality of raised rib-like elements that provide or improve upon the elasticity of the drawtape.
While raised rib-like elements can improve elasticity of a drawtape, they also have some drawbacks. For example, a ribbed drawtape can mechanically engage with the thermoplastic film of the hem as the drawtape moves within the hem. This mechanical engagement leads to a greater amount of force required to pull the drawtape. In instances in which the hem has multiple layers of thermoplastic film, the mechanical engagement with the inner layer of thermoplastic film can cause the inner layer to invert independently from the outer layer of thermoplastic film and bunch at the hem hole, thus requiring even greater force to cinch the drawtape.
In order to increase elasticity along the length of the drawtape, the plurality of raised rib-like elements are oriented to extend across the width of the drawtape (e.g., in a straight line from the top of the drawtape to the bottom of the drawtape in a direction perpendicular to the length of the drawtape). Thus, the plurality of raised rib-like elements lead to increased engagement with the thermoplastic film of the hem as the drawtape moves within the hem. In some instances, the engagement with the thermoplastic film of the hem (and the force required to pull the drawtape out of the hem) increases with the degree to which the raised rib-like elements protrude from the planar face of the drawtape. Other issues often associated with drawtapes include twisting of the drawtape within the hem and tracking of the drawtape during formation of the bag.
Accordingly, there are a number of considerations to be made with regards to drawtape bags and the interaction of a drawtape with its corresponding hem.
One or more embodiments of the present disclosure provide benefits and/or solve one or more of the foregoing or other problems in the art with thermoplastic bags having drawtapes that include deformation patterns resulting in reduced mechanical engagement as the drawtape moves within the hem portion of the bag. In particular, in one or more embodiments, a thermoplastic bag includes a drawtape having a plurality of ribs and a plurality of web areas that are out of plane with the ribs. For example, the plurality of ribs can include raised rib-like elements that provide or increase an elasticity of the drawtape. In some instances, the ribs are mirrored across an axis that corresponds to (e.g., runs along) the length of the drawtape. In some cases, each rib extends across the drawtape in a non-parallel direction with respect to the width of the drawtape. Accordingly, the deformation pattern formed by the plurality of ribs reduces the mechanical engagement between the drawtape and the hem portion, thereby, reducing the force required to pull the drawtape at least partially out of the hem portion.
One or more embodiments include a thermoplastic bag comprising a layer of thermoplastic material, a hem portion formed from the layer of thermoplastic material along an edge of the layer of thermoplastic material, and a drawtape within the hem portion. The drawtape includes a plurality of ribs that are mirrored across an axis running along a length of the drawtape. The drawtape further includes a plurality of web areas, the plurality of web areas separating and connecting ribs of the plurality of ribs, wherein the plurality of web areas is out of plane with the ribs of the plurality of ribs so as to create recesses between adjacent ribs of the plurality of ribs.
One or more further embodiments include a thermoplastic bag comprising a first sidewall and a second sidewall opposite the first sidewall. The first and second sidewalls are joined along a first side edge, an opposite second side edge, and a bottom edge. The thermoplastic bag also includes a hem portion along a top of at least one of the first sidewall or the second sidewall and a drawtape within the hem portion. The drawtape includes a plurality of ribs, wherein a rib length associated with each rib extends across the drawtape in a non-parallel direction with respect to a width of the drawtape. The drawtape further includes a plurality of web areas, the plurality of web areas separating and connecting ribs of the plurality of ribs, wherein the plurality of web areas is out of plane with the ribs of the plurality of ribs so as to create recesses between adjacent ribs of the plurality of ribs.
Additionally, one or more embodiments include a method of manufacturing thermoplastic bags having low-friction, elastic drawtapes. The method involves advancing a drawtape through a pair of intermeshing rollers to generate: a plurality of ribs that are mirrored across an axis corresponding to a length of the drawtape, wherein a rib length associated with each rib extends across the drawtape in a non-parallel direction with respect to a width of the drawtape; and a plurality of web areas, the plurality of web areas separating and connecting ribs of the plurality of ribs, wherein the plurality of web areas is out of plane with the ribs of the plurality of ribs so as to create recesses between adjacent ribs of the plurality of ribs. The method further includes inserting the drawtape into a hem portion of a thermoplastic film. Further, the method includes forming the thermoplastic film into a bag.
Additional features and advantages of exemplary implementations of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of such exemplary embodiments. The features and advantages of such embodiments may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims or may be learned by the practice of such exemplary embodiments as set forth hereinafter.
This disclosure will describe one or more embodiments of the invention with additional specificity and detail by referencing the accompanying figures. The following paragraphs briefly describe those figures, in which:
One or more embodiments of the present disclosure include a thermoplastic bag having a low-friction drawtape within a hem portion of the thermoplastic bag. In particular, in one or more embodiments, a thermoplastic bag includes a drawtape that has been deformed to include a pattern of ribs that increases elasticity and reduces the mechanical interactions between the drawtape and the hem portion of the thermoplastic bag (and the resulting friction) as a user pulls the drawtape. For example, the ribs can extend across the drawtape in a direction that is non-parallel with respect to the width of the drawtape. In other words, the ribs can extend across the drawtape in a direction other than in a straight line from the top of the drawtape to the bottom of the drawtape. In some instances, the pattern of ribs is symmetrical about an axis runs along, or is parallel to, a length of the drawtape. Further, in some embodiments, the ribs include raised rib-like elements that protrude from the planar surface of the drawtape and increase the elasticity of the drawtape.
As mentioned, in one or more embodiments, the drawtape includes a plurality of ribs. Further, the drawtape can include a plurality of web areas. For example, in some implementations, the plurality of web areas separates and connects ribs of the plurality of ribs. Further, the plurality of web areas is out of plane with the ribs so as to create recesses between adjacent ribs. To illustrate, in some embodiments, the ribs extend outward from the plurality of web areas so that the ribs form raised areas of thermoplastic film and the recesses created by the plurality of web areas form relatively lower areas of thermoplastic film.
In one or more embodiments, the plurality of ribs and the plurality of web areas are formed using a deformation process. For example, the ribs can include raised rib-like elements formed using a structural elastic-like film (SELF) process. In other instances, the plurality of ribs and the plurality of web areas are formed using a ring rolling or an embossing process. In some cases, the plurality of ribs and the plurality of web areas are formed using a phased deformation process.
As further mentioned, in some embodiments, the ribs can extend across the drawtape in a non-parallel direction with respect to the width of the drawtape. In particular, the width of the drawtape can include the distance between the top edge of the drawtape and the bottom edge of the drawtape. Accordingly, the ribs can extend across the drawtape in a direction other than a straight line between the top edge and the bottom edge, which is parallel to the width of the drawtape. As an example, the ribs can extend across the drawtape at an angle that is between being parallel with the width of the drawtape and being perpendicular to the width of the drawtape. In one or more embodiments, the non-parallel direction causes the ribs to point towards a hole in the hem portion (e.g., a hem hole) that exposes the drawtape.
Additionally, as mentioned, in some instances, the ribs are further mirrored across an axis that extends along a length of the drawtape. For example, in some cases, each rib includes a first component on a first side of the axis that extends from the axis across the drawtape in a non-parallel direction with respect to the width of the drawtape and a second component on a second side of the axis that connects to the first component at the axis and mirrors the non-parallel direction of the first component. In other words, each rib is symmetrical about the axis corresponding to the length of the drawtape. In some cases, each rib is positioned entirely on one side of the axis and corresponds to another rib positioned entirely on the other side of the axis. In other words, while the pattern of ribs is symmetrical about the axis corresponding to the length of the drawtape, the ribs themselves may not be.
In one or more embodiments, the pattern of ribs includes a pattern of non-linear components, such as a pattern of chasing arrows, chasing crescents, chasing parabolas, chasing hyperbolas, or a combination of these. In some embodiments, the pattern of ribs includes a pattern of linear components (e.g., straight lines). In some cases, the pattern of ribs includes a pattern comprising a combination of linear components and non-linear components.
Further, in some instances, the plurality of ribs can include ribs of varying rib heights. For example, in some cases, the plurality of ribs includes a first set of ribs having a first rib height and a second set of ribs having a second rib height. In some cases, one or more of the ribs from the plurality of ribs varies in height. For example, a rib can include a height that decreases from the center of the rib to the edge of the rib.
As illustrated by the foregoing discussion, the present disclosure utilizes a variety of terms to describe feature and benefits of one or more embodiments. Additional detail is now provided regarding the meaning of these terms. As used herein, the term “hem portion” (or “hem”) refers to a portion of a thermoplastic bag that houses a drawtape. For example, a hem portion can include an enclosed channel that houses the drawtape. In some cases, a hem portion is formed using the same thermoplastic material used to form a sidewall of the thermoplastic bag. The hem portion of a thermoplastic bag can extend side-to-side between, but does not include, opposing side seals (or tape seals) of the thermoplastic bag.
In some cases, a hem portion of a thermoplastic bag includes a hem hole. As used herein, the term “hem hole” refers to an aperture in the hem. In particular, a hem hole can refer to an opening in the hem portion of a thermoplastic bag that exposes a portion of the drawtape housed within the hem. Accordingly, the drawtape can be pulled at least partially out through the hem hole to close the thermoplastic bag. In some cases, as will be illustrated below, a thermoplastic bag includes multiple hem portions, each having a hem hole that exposes respective portions of the drawstring.
As indicated above, a drawstring can include a pattern of deformations. As used herein, the term “deformation” (or “deformations”) refers to one or more structures permanently formed in a thermoplastic film and/or a drawtape. For example, deformations can comprise alternating thicker ribs and thinner webs formed from ring rolling, raised rib-like elements and their corresponding web areas formed from SELF'ing, or displaced designs formed by embossing. Relatedly, as used herein, the term “deformation pattern” refers to a series of repeating deformations. For example, a deformation pattern can refer to a plurality of ribs (e.g., raised rib-like elements) and a plurality of web areas that repeat (e.g., in shape, direction, rib height, etc.) across the surface upon which the deformation pattern exists.
More particularly, a deformation pattern can include a pattern of ribs and a pattern of web areas that connect to form an overall pattern. Indeed, as used herein, the term “pattern of ribs” refers to a series of repeating ribs. In particular, the ribs can include a shape and/or orientation that is repeated throughout the series. To illustrate, a pattern of ribs can include a pattern of non-linear components, such as a pattern of chasing arrows, a pattern of chasing crescents, a pattern of chasing parabolas, a pattern of chasing hyperbolas, or a pattern consisting of some combination of arrows, crescents, parabolas, and/or hyperbolas. In some cases, a pattern of ribs includes a pattern of linear components, such as a pattern of lines. In some implementations, a pattern of ribs includes a combination of linear and non-linear components. As used herein, the term “pattern of web areas” refers to a series of repeating web areas. In particular, a pattern of web areas can form the recesses between adjacent ribs in a pattern of ribs.
As used herein, the term “rib height” refers to a degree of protrusion from a planar surface. For example, a rib height can refer to a degree to which a rib extends from a planar surface formed by a web area—the web area forming a recess between adjacent ribs. A rib height can vary across a single rib. For example, a rib height can decrease from a center of a rib to the edge of the rib or vice versa. In some cases, a rib height can vary among a set of ribs where each rib has a consistent rib height from center-to-edge but has a different rib height than other ribs in the set.
Additionally, as used herein, the term “elasticity” refers to a quality of a thermoplastic material and/or drawtape that is associated with stretchiness. In particular, elasticity can refer to the ability of a thermoplastic material and/or drawtape to resume its normal shape after being stretched or compressed. In some cases, the elasticity of a thermoplastic bag and its drawstring allow the thermoplastic bag and drawstring to more easily be fitted over the rim of a bin or receptable in which the thermoplastic bag is placed.
In some cases, a thermoplastic film—used to form a thermoplastic bag—includes multiple layers of thermoplastic material. As used herein, the terms “lamination,” “laminate,” and “laminated film,” refer to the process and resulting product made by bonding together two or more layers of a film or other material. The term “bonding,” when used in reference to bonding of multiple layers of a multi-layer film, may be used interchangeably with “lamination” of the layers. According to methods of the present disclosure, adjacent layers of a multi-layer film are laminated or bonded to one another. The bonding purposely results in a relatively weak bond between the layers that has a bond strength that is less than the strength of the weakest layer of the film. This allows the lamination bonds to fail before the film layer, and thus the bond, fails.
The term laminate is also inclusive of coextruded multi-layer films comprising one or more tie layers. As a verb, “laminate” means to affix or adhere (by means of, for example, adhesive bonding, pressure bonding, ultrasonic bonding, corona lamination, and the like) two or more separately made film articles to one another so as to form a multi-layer structure. As a noun, “laminate” means a product produced by the affixing or adhering just described.
As used herein the terms “partially discontinuous bonding” or “partially discontinuous lamination” refers to lamination of two or more layers where the lamination is substantially continuous in the machine direction or in the transverse direction, but not continuous in the other of the machine direction or the transverse direction. Alternately, partially discontinuous lamination refers to lamination of two or more layers where the lamination is substantially continuous in the width of the article but not continuous in the height of the article, or substantially continuous in the height of the article but not continuous in the width of the article. More particularly, partially discontinuous lamination refers to lamination of two or more layers with repeating bonded patterns broken up by repeating unbounded areas in either the machine direction or the transverse direction or both. Both partially discontinuous and discontinuous are types of non-continuous bonding (i.e., bonding that is not complete and continuous between two surfaces).
In addition to non-continuous bonding, one or more implementations include incrementally stretching a thermoplastic film. For example, one or more implementations includes incrementally stretching a thermoplastic film using MD ring rolling, TD ring rolling, DD ring rolling, the formation of strainable networks, or combinations thereof. Incrementally stretching a thermoplastic film using the methods described herein can impart ribs or other structures to the film and increase or otherwise modify one or more of the tensile strength, tear resistance, impact resistance, or elasticity of the film. Furthermore, one or more embodiments involve stretching processes with ambient or cold (non-heated) conditions. This differs significantly from most conventional processes that stretch films under heated conditions. Stretching under ambient or cold conditions in accordance with one or more implementations can constrain the molecules in the thermoplastic film so they are not as easily oriented as under heated conditions. Such cold incremental stretching can help provide the unexpected result of maintaining or increasing the strength of a thermoplastic film, despite a reduction in gauge.
Relatively weak bonding and stretching can be accomplished simultaneously through one or more suitable techniques. For example, bonding and stretching may be achieved by pressure (for example MD ring rolling, TD ring rolling, helical or DD ring rolling, stainable network lamination or SELFing, or embossing), or with a combination of heat and pressure. Alternately, a manufacturer can first stretch the films and then bond the films using one or more bonding techniques. For example, one or more implementations can include ultrasonic bonding to lightly laminate the films. Alternately or additionally, adhesives can laminate the films. Treatment with a Corona discharge can enhance any of the above methods. In one or more embodiments, the contacting surfaces/layers can comprise a tacky material to facilitate lamination. Prior to lamination, the separate films can be film or can be subject to separate processes, such as stretching, slitting, coating and printing, and corona treatment.
As used herein, the term “substantially,” in reference to a given parameter, property, or condition, means to a degree that one of ordinary skill in the art would understand that the given parameter, property, or condition is met within a degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0% met, at least 95.0% met, at least 99.0% met, or even at least 99.9% met.
As used herein, the term “flexible” refers to materials that are capable of being flexed or bent, especially repeatedly, such that they are pliant and yieldable in response to externally applied forces. Accordingly, “flexible” is substantially opposite in meaning to the terms inflexible, rigid, or unyielding. Materials and structures that are flexible, therefore, may be altered in shape and structure to accommodate external forces and to conform to the shape of objects brought into contact with them without losing their integrity. In accordance with further prior art materials, web materials are provided which exhibit an “elastic-like” behavior in the direction of applied strain without the use of added traditional elastic. As used herein, the term “elastic-like” describes the behavior of web materials which when subjected to an applied strain, the web materials extend in the direction of applied strain, and when the applied strain is released the web materials return, to a degree, to their pre-strained condition.
As used herein, any relational terms such as “first,” “second,” and “third,” “inner,” “outer,” “upper,” “lower,” “side,” “top,” “bottom,” etc. are for clarity and convenience in understanding the present disclosure and accompanying drawings and does not connote or depend on any specific preference, orientation, or order, except where the context clearly indicates otherwise. For example, the relational terms may refer an orientation of a multi-layer bag while disposed within a receptacle (e.g., a trash can) for use. Film Materials
As an initial matter, the thermoplastic material of the films of one or more implementations (e.g., used to form the thermoplastic bags or drawtape) can include, but are not limited to, thermoplastic polyolefins, including polyethylene and copolymers thereof and polypropylene and copolymers thereof. The olefin-based polymers can include the most common ethylene or propylene-based polymers such as polyethylene, polypropylene, and copolymers such as ethylene vinylacetate (EVA), ethylene methyl acrylate (EMA) and ethylene acrylic acid (EAA), or blends of such polyolefins.
Other examples of polymers suitable for use as films in accordance with the present disclosure may include elastomeric polymers. Suitable elastomeric polymers may also be biodegradable or environmentally degradable. Suitable elastomeric polymers for the film include poly(ethylene-butene), poly(ethylene-hexene), poly(ethylene-octene), poly(ethylene-propylene), poly(styrene-butadiene-styrene), poly(styrene-isoprene-styrene), poly(styrene-ethylene-butylene-styrene), poly(ester-ether), poly(ether-amide), poly(ethylene-vinylacetate), poly(ethylene-methylacrylate), poly(ethylene-acrylic acid), oriented poly(ethylene-terephthalate), poly(ethylene-butylacrylate), polyurethane, poly(ethylene-propylene-diene), ethylene-propylene rubber, nylon, etc.
Some of the examples and description herein below refer to films formed from linear low-density polyethylene. The term “linear low-density polyethylene” (LLDPE) as used herein is defined to mean a copolymer of ethylene and a minor amount of an olefin containing 4 to 10 carbon atoms, having a density of from about 0.910 to about 0.926, and a melt index (MI) of from about 0.5 to about 10. For example, some examples herein use an octene comonomer, solution phase LLDPE (MI=1.1; p=0.920). Additionally, other examples use a gas phase LLDPE, which is a hexene gas phase LLDPE formulated with slip/AB (MI=1.0; p=0.920). Still further examples use a gas phase LLDPE, which is a hexene gas phase LLDPE formulated with slip/AB (MI=1.0; p=0.926). One will appreciate that the present disclosure is not limited to LLDPE, and can include “high density polyethylene” (HDPE), “low density polyethylene” (LDPE), and “very low-density polyethylene” (VLDPE). Indeed, films made from any of the previously mentioned thermoplastic materials or combinations thereof can be suitable for use with the present disclosure.
Some embodiments of the present disclosure may include any flexible or pliable thermoplastic material that may be formed or drawn into a web or film. Furthermore, each thermoplastic film may include a single layer or multiple layers of thermoplastic materials. The thermoplastic material may be opaque, transparent, translucent, or tinted. Furthermore, the thermoplastic material may be gas permeable or impermeable.
For example, films of the thermoplastic films described herein may include a single film formed from one, two, three, or more layers of thermoplastic material. In some implementations, the film may include a single layer film, comprising a single layer. In other implementations, the film can comprise a two-layer film, including a first layer and a second layer. The first and second layers can be coextruded. In such implementations, the first and second layers may optionally include different grades of thermoplastic material and/or include different additives, including polymer additives. In yet other implementations, the film be a tri-layer film, including a first layer, a second layer, and a third layer. In yet other implementations, a film may include more than three layers. The tri-layer film can include an A:B:C configuration in which all three layers vary in one or more of gauge, composition, color, transparency, or other properties. Alternatively, the tri-layer film can comprise an A:A:B structure or A:B:A structure in which two layers have the same composition, color, transparency, or other properties. In an A:A:B structure or A:B:A structure the A layers can comprise the same gauge or differing gauge. For example, in an A:A:B structure or A:B:A structure the film layers can comprise layer ratios of 20:20:60, 40:40:20, 15:70:15, 33:34:33, 20:60:20, 40:20:40, or other ratios.
Additional additives that may be included in one or more embodiments include slip agents, anti-block agents, voiding agents, or tackifiers. Additionally, one or more implementations of the present disclosure include films that are devoid of voiding agents. Some examples of inorganic voiding agents, which may further provide odor control, include the following but are not limited to: calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, calcium oxide, magnesium oxide, titanium oxide, zinc oxide, aluminum hydroxide, magnesium hydroxide, talc, clay, silica, alumina, mica, glass powder, starch, charcoal, zeolites, any combination thereof, etc. Organic voiding agents, polymers that are immiscible in the major polymer matrix, can also be used. For instance, polystyrene can be used as a voiding agent in polyethylene and polypropylene films.
Further additives that may be included in one or more embodiments include natural oils. For example, the additives may include thyme oil, mint oil, lemon grass oil, tea tree oil, cinnamon bark oil, methyl jasmonate, etc. Yet further additives may include zinc pyrithione (“ZPT”) and copper pyrithione (“CPT”), which inhibit microbial growth.
One of ordinary skill in the art will appreciate in view of the present disclosure that manufacturers may form the films or webs to be used with the present disclosure using a wide variety of techniques. For example, a manufacturer can form a precursor mix of the thermoplastic material and one or more additives. The manufacturer can then form the film(s) from the precursor mix using conventional flat or cast extrusion or coextrusion to produce monolayer, bilayer, or multilayer films. Alternatively, a manufacturer can form the films using suitable processes, such as, a blown film process to produce monolayer, bilayer, or multilayer films. If desired for a given end use, the manufacturer can orient the films by trapped bubble, tenterframe, or other suitable process. Additionally, the manufacturer can optionally anneal the films thereafter.
An optional part of the film-making process is a procedure known as “orientation.” The orientation of a polymer is a reference to its molecular organization, i.e., the orientation of molecules relative to each other. Similarly, the process of orientation is the process by which directionality (orientation) is imposed upon the polymeric arrangements in the film. The process of orientation is employed to impart desirable properties to films, including making cast films tougher (higher tensile properties). Depending on whether the film is made by casting as a flat film or by blowing as a tubular film, the orientation process can require different procedures. This is related to the different physical characteristics possessed by films made by the two conventional film-making processes; casting and blowing. Generally, blown films tend to have greater stiffness and toughness. By contrast, cast films usually have the advantages of greater film clarity and uniformity of thickness and flatness, generally permitting use of a wider range of polymers and producing a higher quality film.
When a film has been stretched in a single direction (monoaxial orientation), the resulting film can exhibit strength and stiffness along the direction of stretch, but can be weak in the other direction (i.e., across the stretch), often splitting when flexed or pulled. To overcome this limitation, two-way or biaxial orientation can be employed to more evenly distribute the strength qualities of the film in two directions. Most biaxial orientation processes use apparatus that stretches the film sequentially, first in one direction and then in the other.
In one or more implementations, the films of the present disclosure are blown film, or cast film. Blown film and cast film is formed by extrusion. The extruder used can be a conventional one using a die, which will provide the desired gauge. Some useful extruders are described in U.S. Pat. Nos. 4,814,135; 4,857,600; 5,076,988; 5,153,382; each of which are incorporated herein by reference in their entirety. Examples of various extruders, which can be used in producing the films to be used with the present disclosure, can be a single screw type modified with a blown film die, an air ring, and continuous take off equipment.
In one or more embodiments, a manufacturer can use multiple extruders to supply different melt streams, which a feed block can order into different channels of a multi-channel die. The multiple extruders can allow a manufacturer to form a multi-layer film with layers having different compositions. Such multi-layer film may later be non-continuously laminated with another layer of film.
In a blown film process, the die can be an upright cylinder with a circular opening. Rollers can pull molten plastic upward away from the die. An air-ring can cool the film as the film travels upwards. An air outlet can force compressed air into the center of the extruded circular profile, creating a bubble. The air can expand the extruded circular cross section by a multiple of the die diameter. This ratio is called the “blow-up ratio.” When using a blown film process, the manufacturer can collapse the film to double the plies of the film. Alternatively, the manufacturer can cut and fold the film, or cut and leave the film unfolded.
In any event, in one or more embodiments, the extrusion process can orient the polymer chains of the blown film. In particular, the extrusion process can cause the polymer chains of the blown film to be predominantly oriented in the machine direction. The orientation of the polymer chains can result in an increased strength in the direction of the orientation. As used herein predominately oriented in a particular direction means that the polymer chains are more oriented in the particular direction than another direction. One will appreciate, however, that a film that is predominately oriented in a particular direction can still include polymer chains oriented in directions other than the particular direction. Thus, in one or more embodiments the initial or starting films (films before being stretched or bonded or laminated in accordance with the principles described herein) can comprise a blown film that is predominately oriented in the machine direction.
The process of blowing up the tubular stock or bubble can further orient the polymer chains of the blown film. In particular, the blow-up process can cause the polymer chains of the blown film to be bi-axially oriented. Despite being bi-axially oriented, in one or more embodiments the polymer chains of the blown film are predominantly oriented in the machine direction (i.e., oriented more in the machine direction than the transverse direction).
The films of one or more implementations of the present disclosure can have a starting gauge between about 0.1 mils to about 20 mils, suitably from about 0.2 mils to about 4 mils, suitably in the range of about 0.3 mils to about 2 mils, suitably from about 0.6 mils to about 1.25 mils, suitably from about 0.9 mils to about 1.1 mils, suitably from about 0.3 mils to about 0.7 mils, and suitably from about 0.4 mils and about 0.6 mils. Additionally, the starting gauge of films of one or more implementations of the present disclosure may not be uniform. Thus, the starting gauge of films of one or more implementations of the present disclosure may vary along the length and/or width of the film.
As an initial matter, one or more layers of the films described herein can comprise any flexible or pliable material comprising a thermoplastic material and that can be formed or drawn into a web or film. As described above, the film includes a plurality of layers of thermoplastic films. Each individual film layer may itself include a single layer or multiple layers. In other words, the individual layers of the multi-layer film may each themselves comprise a plurality of laminated layers. Such layers may be significantly more tightly bonded together than the bonding provided by the purposely weak discontinuous bonding in the finished multi-layer film. Both tight and relatively weak lamination can be accomplished by joining layers by mechanical pressure, joining layers with adhesives, joining with heat and pressure, spread coating, extrusion coating, and combinations thereof. Adjacent sub-layers of an individual layer may be coextruded. Coextrusion results in tight bonding so that the bond strength is greater than the tear resistance of the resulting laminate (i.e., rather than allowing adjacent layers to be peeled apart through breakage of the lamination bonds, the film will tear).
Referring now to the figures,
In some embodiments, the bottom edge 110 or one or more of the first and second side edges 106, 108 can comprise a fold. In other words, the first and second sidewalls 102, 104 may comprise a single unitary piece of material. The top edges 111 of the first and second sidewalls 102, 104 may define an opening 112 to an interior of the thermoplastic bag 100. In other words, the opening 112 may be oriented opposite the bottom edge 110 of the thermoplastic bag 100. Furthermore, when placed in a trash receptacle, the top edges 111 of the first and second sidewalls 102, 104 may be folded over the rim of the receptacle.
In some embodiments, the thermoplastic bag 100 may optionally include a closure mechanism 114 located adjacent to the top edges 111 for at least partially closing the top of the thermoplastic bag 100 to form an at least substantially fully-enclosed container or vessel. As shown in
As further shown in
Further, as shown, the deformation patterns 126a -126b include ribs that extend across the drawtape 116 in a non-parallel direction with respect to the width 130 of the drawtape 116. In particular, the deformation patterns 126a -126b include ribs that extend across the drawtape at an angle that is between being parallel to the width of the drawtape 116 and being perpendicular to the width of the drawtape 116. Though
Additionally, as shown in
By including the deformation patterns 126a -126b, the drawtape 116 reduces the mechanical engagement with the first and second hems 120, 118 as the drawtape 116 moves within the first and second hems 120, 118. For example, as the drawtape 116 is pulled out of the first and second hems 120, 118 through the first and second apertures 124, 122, respectively, the deformation patterns 126a -126b create reduced friction when compared to other drawtapes. Accordingly, the thermoplastic bag 100 requires less force to pull the drawtape 116 out through the first and second apertures 124, 122 to close the thermoplastic bag 100. Further, by including the deformation patterns 126a -126b, the drawtape 116 is less likely to twist within the first and second hems 120, 118. Indeed, the deformation patterns 126a -126b tend to cause the drawtape 116 to lay flat within the first and second hems 120, 118. Furthermore, the deformation patterns 12a-126b can reduce the surface area of the drawtape 116 that comes into contact with the inner surfaces of the hems 120, 118. More specifically, as the ribs of the deformation patterns are raised, in one or more embodiments, the ribs are the substantially the only portions of the drawtape 116 that contact the inner surface of the hems 120, 118. More detail regarding deformation patterns and the ribs and web areas making up such deformation patterns will be discussed below.
Further, as shown, the thermoplastic bag 200 includes a first hem 220 and a second hem 218. As shown, the first hem 220 is formed from the thermoplastic film 206 of the first sidewall 202, and the second hem 218 is formed from the thermoplastic film 206 of the second sidewall 204. Thus, the first and second hems 220, 218 include the single layer of the thermoplastic film 206. In some instances, however, the first hem 220 and/or the second hem 218 can include additional layers of the thermoplastic film 206 or additional layers formed from other thermoplastic films, such as those described above.
Additionally, as shown in
In some cases, a thermoplastic bag includes multiple layers of thermoplastic film.
Further, as shown, the thermoplastic bag 300 includes a first hem 320 and a second hem 318. As shown, the first hem 320 is formed from the first film 306 and the second film 308 of the first sidewall 302, and the second hem 318 is formed from the first film 306 and the second film 308 of the second sidewall 304. Thus, the first and second hems 320, 318 include multiple layers of film. Though
Additionally, as shown in
By including the deformation patterns illustrated in
As mentioned above, the drawtape of a thermoplastic bag can include a deformation pattern that decreases the mechanical engagement between the drawtape and the hem of the thermoplastic bag. In particular, the drawtape can include a pattern of ribs and a pattern of web areas that reduces the friction created as the drawtape is pulled at least partially out of the hem of the thermoplastic bag.
In particular,
Additionally, as shown in
As shown in
Additionally, as shown in
As further shown in
As illustrated in
Additionally, rather than each rib including components that mirror one another across the axis 418 corresponding to the length 422 of the drawtape 404, the drawtape 404 can include ribs that are positioned entirely on one side of the axis 418 and have a corresponding “mirrored” rib on the other side of the axis 418. Accordingly, the plurality of ribs of the drawtape 404 are mirrored across the axis 418 corresponding to the length 422 of the drawtape 404 by having a first set of ribs located above the axis 418 and a mirroring set of ribs located below the axis.
Further, as shown in
Additionally, as illustrated in
In one or more embodiments, each rib of the drawtape 404 includes the same rib height. Further, in some cases, each rib includes a consistent rib height where the height of a rib is the same from the center of the rib to the edge of the rib. In some instances, however, rib height can vary across the ribs of a drawtape 404. For example, the rib height can vary across a single rib. To illustrate, in one or more embodiments, the rib height of a rib decreases from the center of the rib to the edge of the rib or vice versa. In some implementations, the rib height is different among various ribs of a drawtape 404. For example, the drawtape 404 can include a first set of ribs having a first rib height and further include a second set of ribs having a second rib height that is different than the first rib height. Indeed, the rib height can vary in many ways across the drawtape.
For example,
As shown, each rib 508 points towards the hem hole 506 of the hem portion 502. In particular, each rib 508 curves towards the hem hole 506. Indeed, as shown, the pattern of ribs 508 is part of a deformation pattern that is symmetrical about the hem hole 506. Similar to the deformation pattern of ribs of
Similarly,
Similar to the ribs described above, the ribs 608 can provide the drawtape 604 with increased elasticity while also decreasing the force required to pull the drawtape through the hem portion 602 to cinch a bag. In particular, the height of the ribs 608 compared to the rest of the surface of the drawtape 604 can reduce the area of contact between the drawtape 604 and the hem portion 602. The reduction of area of contact reduces friction between the drawtape 604 and the hem portion 602, thereby, increasing the ease of pulling the drawtape 604 through the hem portion 602. Furthermore, the shape the ribs 608 and pointing direction can help guide the drawtape 604 through the hem portion 602 toward the hem hole 606.
As mentioned above, ribs of one or more implementations are non-parallel to the width of the drawtape into which they are formed. The non-parallel orientation to the width can prevent the ribs from catching the inner surface of the hem and causing bunching of the hem portion as the drawtape is pulled through the hem portion. One will appreciate that one or more implementations can include ribs that are not entirely parallel to the width of the drawtape but nonetheless include portions that are parallel to the width of the drawtape. For example,
Particularly, as shown in
Similar to the ribs described above, the ribs 708 can provide the drawtape 704 with increased elasticity while also increasing the ease of travel of the drawtape 704 through the hem portion 702. In particular, the height of the ribs 708 compared to the rest of the surface of the drawtape 704 can help reduce the web areas of the drawtape from contacting the inner surface of the hem portion 702, thereby, reducing friction between the drawtape 704 and the hem portion 702.
As previously suggested, the non-parallel orientation of the ribs with respect to the width of the drawtape 804 can prevent the edges of the ribs from catching the inner surface of the hem portion 802. Indeed, the non-parallel orientation of the ribs with respect to the width of the drawtape 804 can reduce the mechanical forces typically involved as the drawtape 804 is pulled from the hem portion 802. To provide more detail, conventional drawtapes with rib structures often create a significant amount of mechanical force when extracted from a hem, because the length of the rib structures is perpendicular to the length of the drawtape (i.e., perpendicular to the direction of pull) and the ends of the rib structures frictionally snag the hem as the drawtape is pulled.
By reducing the angle between the end portions of the ribs and the direction of pull, the drawtape 804 can reduce the friction created between the drawtape 804 and the hem portion 802. In particular, as the angle between the ribs and the direction of pull becomes more acute, the ribs enable the hem portion 802 to deflect away the ends of the ribs. Accordingly, the potential for frictional snagging reduces, and the drawtape 804 can be extracted from the hem portion 802 with less pulling force required. Though this has been discussed with particular reference to
The ribs included on a drawtape can include various different configurations.
As shown in
As shown in
4 or the ribs composed of a series of lines discussed with reference to
As previously mentioned, in one or more embodiments, the ribs of a drawtape include raised rib-like elements. In particular, the ribs include raised rib-like elements formed through a SELF process (which also forms the web areas). Indeed, in accordance with one implementation, a SELF process may be used to create a drawtape with strainable networks. Indeed, any of the bags mentioned above can include a drawtape created using the SELF process. In some implementations (e.g., where the drawtape includes multiple layers), the SELF process results in discontinuous bonding of adjacent layers. Indeed, the strainable networks can include adjacent bonded and un-bonded regions. U.S. Pat. Nos. 7,942,577; 5,518,801; 6,139,185; 6,150,647; 6,394,651; 6,394,652; 6,513,975; 6,695,476; U.S. Patent Application Publication No. 2004/0134923; and U.S. Patent Application Publication No. 2006/0093766 each disclose processes for forming strainable networks or patterns of strainable networks suitable for use with implementations of the present disclosure. The contents of each of the aforementioned patents and publications are incorporated in their entirety by reference herein. As used herein, the term “strainable network” refers to an interconnected and interrelated group of regions which are able to be extended to some useful degree in a predetermined direction providing the web material with an elastic-like behavior in response to an applied and subsequently released elongation.
In one or more implementations, the plurality of ribs—such as those described above with reference to
Indeed, as suggested above, each roller of a pair of SELF'ing intermeshing rollers can include a first set of ridges oriented in one direction and a second set of ridges oriented in the opposite direction so that a drawtape advanced through the SELF'ing intermeshing rollers would include a first set of raised rib-like elements that point in a first direction and a second set of raised rib-like elements that point in a second direction (e.g., the ribs of the first and second sets of raised rib-like elements point towards a hem hole that exposes a portion of the drawtape).
In some instances, the circular pitch of the ridges of the SELF'ing intermeshing rollers can vary from 40 pitch (0.040 inch) to 200 pitch (0.200 inch). In some instances, the circular pitch varies about the tooling circumference to advantageously provide more elasticity at certain portions of the drawtape. As used herein, the term “pitch” refers to the distance between the tips of two adjacent ridges on the same roller. Another measure, the “depth of engagement” (“DOE”) refers to the amount of overlap between ridges of the different SELF'ing intermeshing rollers during intermeshing. The pitch and depth of engagement of the ridges can determine, at least in part, the amount of incremental stretching and partially discontinuous lamination caused by the phased SELF'ing intermeshing rollers.
As mentioned above, the ribs and web areas of a drawtape can be formed through phased SELF'ing. In some instances, the ribs and web areas are formed via phased ring rolling. In particular, a drawtape can include one or more phased deformation patterns. As used herein, the term “phased deformation pattern” refers to a pattern of deformations that vary from a first side of a drawtape, along a length of the drawtape, to an opposing side of the drawtape. In other words, a phased deformation pattern is a deformation pattern that does not repeat consistently or uniformly across a length of a drawtape. For example, a phased deformation pattern can include a first zone with a first deformation pattern and a second zone with a second deformation pattern, where the first and second zones are aligned, at least partially, along a length of the thermoplastic bag. Alternatively, a first zone can have a deformation pattern that is deeper than a second zone.
To create phased deformation patterns, one or more embodiments include the use of the intermeshing rollers that are sized and configured based on a length of a drawtape. In other words, the intermeshing rollers are phased or registered to correspond to a multiple of a length of the drawtape. The intermeshing rollers have teeth or gears that vary along the circumference of the intermeshing rollers so as to produce a pattern in a drawtape that varies from one side of a drawtape to an opposing side of the drawtape.
By phasing the ring rolling or SELF'ing of a drawtape, one or more implementations provide a drawtape with zones or sections with tailored strength and/or aesthetic characteristics. For example, one or more implementations include reducing or eliminating ring rolling or SELF'ing in areas of the drawtape in which seals are formed. Still further implementations include drawtapes with varying patterns of ring rolling or SELF'ing that create zones or sections with unique performance in the machine direction, transverse direction, or both. For instance, one or more implementations include drawtapes with zones that have differing functional properties (stretch differently or have differing strength or other material properties) or aesthetic properties.
Thus, considering
As further shown by
As shown in
The edges of the first thicker regions 1204—in other words, where the material transitions from the first thicker regions 1204 to the stretched, thinner transitional regions 1208— can include the edges of the raised rib-like elements 1202b. Indeed, as mentioned above, in one or more embodiments, a drawtape can include a plurality of ribs of varying rib height among across ribs collectively or individually. For raised rib-like elements of individually-varying rib height, the rib height can differ from the center of the raised rib-like element to the edge of the raised rib-like element.
As shown by
The raised rib-like elements 1202b can undergo a substantially “geometric deformation” prior to a “molecular-level deformation.” As used herein, the term “molecular-level deformation” refers to deformation, which occurs on a molecular level and is not discernible to the normal naked eye. That is, even though one may be able to discern the effect of molecular-level deformation, e.g., elongation or tearing of the film, one is not able to discern the deformation, which allows or causes it to happen. This is in contrast to the term “geometric deformation,” which refers to deformations that are generally discernible to the normal naked eye when a SELF'ed drawtape or articles embodying such a drawtape are subjected to an applied load or force. Types of geometric deformation include, but are not limited to bending, unfolding, and rotating.
Thus, upon application of a force, the raised rib-like elements 1202b can undergo geometric deformation before undergoing molecular-level deformation. For example, a strain applied to the drawtape 1200 in a direction perpendicular to the major axes of the raised rib-like elements 1202b can pull the raised rib-like elements 1202b back into plane with the web areas 1210 prior to any molecular-level deformation of the raised rib-like elements 1202b. Geometric deformation can result in significantly less resistive forces to an applied strain than that exhibited by molecular-level deformation.
In some instances, a drawtape includes raised rib-like elements of varying length. It should be noted, however, that a drawtape can include a deformation pattern where all of the raised rib-like elements are of the same length. Further, it should be noted that the drawtape 1200 includes a particular deformation pattern that facilitates discussion of raised rib-like elements and corresponding web areas. However, a drawtape can include other deformation patterns, such as those discussed above with reference to
By utilizing a drawtape that includes raised rib-like elements, a thermoplastic bag can more easily be stretched to fit over the rim of a bin, such as a trash receptacle. As the raised rib-like elements improve upon the elasticity of the drawtape, the drawtape can facilitate gripping the rim of the bin once the thermoplastic bag has been placed inside. By using a drawtape with a deformation pattern, such as those described above with reference to
Though
As discussed above, a thermoplastic bag can include a hem portion and a drawtape within the hem portion. The drawtape can include a plurality of ribs (e.g., raised rib-like elements formed from a SELF'ing process) and a plurality of web areas. The ribs can provide increased elasticity for the drawtape and further reduce the force needed to pull the drawtape from the hem portion by reducing the friction created between the drawtape and the hem portion. In some implementations, a thermoplastic bag further includes a hem portion having a deformation pattern, which can reduce the surface area of the hem portion that contacts the ribbed drawtape thereby further reducing friction and drag.
For example,
The raised rib-like elements 1308a can have height that extends away from the web areas 1310a such that the plurality of ribs of the drawtape 1304a generally come into contact with the raised rib-like elements 1308a rather than the web areas 1310a such that the surface area of the hem portion 1302a (e.g., the inner layer of the hem portion) that comes into contact with the drawtape 1304a as the drawtape 1304a moves is reduced. By further reducing the mechanical engagement, the thermoplastic bag 1300a reduces the friction that is created between the hem portion 1302a and the drawtape 1304a as the drawtape 1304a moves. Thus, the thermoplastic bag 1300a requires even less force to pull the drawtape 1304a from the hem portion 1302a than a bag with a hem portion lacking deformations.
Patent Application No. PCT/US2018/058998 filed on May 16, 2019 and entitled “THERMOPLASTIC FILMS AND BAGS WITH COMPLEX STRETCH PATTERNS AND METHODS OF MAKING THE SAME,” hereby incorporated by reference in its entirety. The third or bottom region 1318a is a flat portion or undeformed portion.
In addition to raised-rib like elements created by SELF'ing, one or more implementations include hem portions with deformation patterns formed from ring rolling. For example,
The thicker ribs 1320 can have height that extends away from the web areas 1322 such that the plurality of ribs of the drawtape 1304b generally come into contact with the thicker ribs 1320 rather than the web areas 1322 such that the surface area of the hem portion 1302b (e.g., the inner layer of the hem portion) that comes into contact with the drawtape 1304b as the drawtape 1304b moves is reduced. By further reducing the mechanical engagement, the thermoplastic bag 1300b reduces the friction that is created between the hem portion 1302b and the drawtape 1304b as the drawtape 1304b moves. Thus, the thermoplastic bag 1300b requires even less force to pull the drawtape 1304b from the hem portion 1302b than a bag with a hem portion lacking deformations. Furthermore, as the thicker ribs 1320 extend in the same direction that the drawtape 1304b is pulled, the thicker ribs 1320 can help guide the drawtape 1304b as the drawtape is pulled through the hem portion 1302b.
Along related lines,
The thicker ribs 1324 can have height that extends away from the web areas 1326 such that the plurality of ribs of the drawtape 1304c generally come into contact with the thicker ribs 1324 rather than the web areas 1326 such that the surface area of the hem portion 1302c (e.g., the inner layer of the hem portion) that comes into contact with the drawtape 1304c as the drawtape 1304c moves is reduced. By further reducing the mechanical engagement, the thermoplastic bag 1300c reduces the friction that is created between the hem portion 1302c and the drawtape 1304c as the drawtape 1304c moves. Thus, the thermoplastic bag 1300c requires even less force to pull the drawtape 1304c from the hem portion 1302c than a bag with a hem portion lacking deformations.
In addition to the foregoing, in one or more implementations a hem portion comprises a deformation pattern of contact areas such as those described in International Patent Application No. PCT/US2020/024143 filed on Mar. 23, 2020 and entitled “MULTI-FILM THERMOPLASTIC STRUCTURES AND BAGS HAVING VISUALLY-DISTINCT CONTACT AREAS AND METHODS OF MAKING THE SAME,” hereby incorporated by reference in its entirety. For example,
Furthermore, the contact areas 1330 are slightly recessed compared to surrounding unbonded regions 1328 such that the plurality of ribs of the drawtape 1304d generally come into contact with the unbonded regions 1328 rather than the web areas contact areas 1330 such that the surface area of the hem channel 1302d (e.g., the inner layer of the hem portion) that comes into contact with the drawtape 1304d as the drawtape 1304d moves is reduced. By further reducing the mechanical engagement, the thermoplastic bag 1300d reduces the friction that is created between the hem channel 1302d and the drawtape 1304d as the drawtape 1304d moves. Thus, the thermoplastic bag 1300d requires even less force to pull the drawtape 1304d from the hem channel 1302d than a bag with a hem portion lacking deformations.
As shown in
The third region 1318b of the multi-film thermoplastic bag 1300d is a flat portion of the multi-film thermoplastic bag 1300d. In one or more implementations, the second region 1316b includes SELF'ed or ring rolled patterns as described above. As shown by
In one or more implementations, it is desirable to have more thermoplastic material in areas of the bag 1300d (e.g., in the grab zones) that are often susceptible to tears, rips, or other failures. For example, the grab zone 1340 lacks significant deformations and is otherwise less stretched relative to the second region 1316b. The pattern of contact areas in the grab zone 1340 provide the region with pleasing aesthetics and visual cues of strength and durability without substantially changing the gauge of the films in the grab zone 1340.
Thus,
By including a deformation pattern of ribs and web areas on the hem portion as well as the corresponding drawtape, a thermoplastic bag further reduces the mechanical engagement as the drawtape moves within the hem portion. For example, the thermoplastic bag further reduces the surface area of the hem portion (e.g., the inner layer of the hem portion) that comes into contact with the drawtape as the drawtape moves. By further reducing the mechanical engagement, the thermoplastic bag reduces the friction that is created between the hem portion and the drawtape as the drawtape moves. Thus, the thermoplastic bag requires less force to pull the drawtape from the hem portion. As mentioned, in some cases, the deformation pattern formed on the hem portion is selected to match or complement the deformation pattern on the drawtape, such as by minimizing the surface areas of the hem portion and the drawtape that come into contact.
One or more implementations of the present invention can also include methods of forming thermoplastic bags having drawtapes that include deformation patterns, such as those described above.
For example, various acts of the method described can be omitted or expanded, additional acts can be included, and the order of the various acts of the method described can be altered as desired.
In particular, to produce thermoplastic bags having drawtapes that include the deformation patterns described above, continuous webs of thermoplastic material may be processed through a high-speed manufacturing environment such as that illustrated in
The process 1400 further can optionally involve unwinding a second continuous web or film 1482 of a second thermoplastic material from a roll 1402 and advancing the web along a machine direction 1406. The second film 1482 can comprise, a width, and/or a thickness that is similar or the same as the first film 1480. In alternative one or more implementations, one or more of the width, and/or thickness of the second film 1482 can differ from that of the first film 1480.
To provide sidewalls of the finished bag, the film(s) 1480, 1482 may be folded into a first half 1422 and an opposing second half 1424 about the machine direction 1406 by a folding operation 1420. When so folded, the first edge 1410 may be moved adjacent to the second edge 1412 of the film(s) 1480, 1482. Accordingly, the width of the film(s) 1480, 1482 proceeding in the machine direction 1406 after the folding operation 1420 may be a width 1428 that may be half the initial width 1408. As may be appreciated, the portion mid-width of the unwound film(s) 1480, 1482 may become the outer edge 1426 of the folded web. In any event, the hems may be formed along the adjacent first and second edges 1410, 1412 and a drawtape 1432 may be inserted during a hem and drawtape operation 1430.
As shown in
By forming deformation patterns on drawtapes (e.g., the patterns described above), the process 1400 improves tape tracking due to the self-centering aspect of the symmetric ribbing pattern about the axis that extends across the drawtape lengthwise. Further, the process 1400 maintains an important aspect of laser detection to register non-oriented blank to seal.
To form deformations (e.g., phased deformations or non-phased deformations) in the film(s) 1480, 1482 and optionally bond multiple films together, the processing equipment includes pairs of SELF'ing intermeshing rollers (represented by the SELF'ing intermeshing rollers 1442, 1443) such as those described herein above. The folded film(s) 1480, 1482 may be advanced along the machine direction 1406 between the pairs of SELF'ing intermeshing rollers, which may be set into rotation to impart the resulting deformation patterns 1468a -1468b. To facilitate formation of the deformations, the each SELF'ing intermeshing roller of the pairs of SELF'ing intermeshing rollers may be forced or directed against each other by, for example, hydraulic actuators. The pressure at which the rollers are pressed together may be in a first range from 30 PSI (2.04 atm) to 100 PSI (6.8 atm), a second range from 60 PSI (4.08 atm) to 90 PSI (6.12 atm), and a third range from 75 PSI (5.10 atm) to 85 PSI (5.78 atm). In one or more implementations, the pressure may be about 80 PSI (5.44 atm). It should be noted that
The processing equipment may include pinch rollers 1462, 1464 to accommodate the width 1428 of the film(s) 1480, 1482. To produce the finished bag, the processing equipment may further process the folded film(s) 1480, 1482. For example, to form the parallel side edges of the finished bag, the film(s) 1480, 1482 may proceed through a sealing operation 1470 in which heat seals 1472 may be formed between the folded edge 1426 and the adjacent edges 1410, 1412. The heat seals may fuse together the halves 1422, 1424 of the folded film(s) 1480, 1482. The heat seals 1472 may be spaced apart along the folded film(s) 1480, 1482 and in conjunction with the folded outer edge 1426 may define individual bags. The heat seals 1472 may be made with a heating device, such as, a heated knife. A perforating operation 1481 may form perforations 1489 in the heat seals 1472 with a perforating device, such as, a perforating knife so that individual bags 1490 may be separated from the film(s) 1480, 1482. In one or more implementations, the film(s) 1480, 1482 may be folded one or more times before the folded film(s) 1480, 1482 may be directed through the perforating operation. The film(s) 1480, 1482 embodying the bags 1490 may be wound into a roll 1486 for packaging and distribution. For example, the roll 1486 may be placed in a box or a bag for sale to a customer. As shown, the height 1458 of the bags 1490 is the same as, or substantially similar to, the width 1428 of the film(s) 1480, 1482.
In one or more implementations of the process, a cutting operation 1488 may replace the perforating operation 1481. The film(s) 1480, 1482 is directed through a cutting operation 1488 which cuts the film(s) 1480, 1482 at location into individual bags 1490 prior to winding onto a roll 1486 for packaging and distribution. For example, the roll 1486 may be placed in a box or bag for sale to a customer. The bags may be interleaved prior to winding into the roll 1486. In one or more implementations, the film(s) 1480, 1482 may be folded one or more times before the folded web is cut into individual bags. In one or more implementations, the bags 1490 may be positioned in a box or bag, and not onto the roll 1486.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described implementations are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims priority to U.S. Provisional Application No. 63/203,564, entitled “THERMOPLASTIC BAGS WITH DRAWTAPES HAVING RIBBED DEFORMATION PATTERNS FOR REDUCED FRICTION AND METHODS OF MAKING THE SAME,” filed Jul. 27, 2021, the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63203564 | Jul 2021 | US |
