The present disclosure relates to films, and particularly to breathable films.
According to the present disclosure, a breathable film includes one or more layers of an extruded resin.
In illustrative embodiments, the extruded resin can include a PCR resin formed from or more raw ingredients. The breathable film may be formed from a process including machine-direction and cross direction stretching. For example, an Elmendorf tear strength of the one or more layers in the cross direction may be about three times larger than the Elmendorf tear strength of the one or more layers in the machine direction; and a trapezoidal tear strength of the one or more layers in the cross direction may be about 1.9 times larger than the trapezoidal tear strength of the one or more layers in the machine direction.
Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived.
The detailed description particularly refers to the accompanying figures in which:
Recyclable raw materials may be used to generate a breathable film. For example, one or more raw materials may be blended together to make a breathable film. The film of the present embodiments can be made from a recycled polymer. In some embodiments, the raw materials can include post-consumer recycled (PCR) resins that can be used in the buildup of the manufacture of a breathable film. PCR resins can include a material made from recycled plastic, such as water and beverage bottles and other packaging, and offers a more sustainable source for making packaging films, containers, sheets, and many of the products that would otherwise be developed with virgin plastic resin. The film can be a monolayer film, though in some embodiments, the film can be a multi-layer film.
PCR resins used to make the films of the present embodiments result in films having unique and/or unexpected properties. For example, recycled materials can contain foreign particulates and/or impurities that can contaminate the film, thereby making it unusable for its intended purpose. Some recycled materials are not used to make quality breathable films, and a person having ordinary skill in the art would recognize that minimizing an amount of the PCR resin in the film typically yields superior results. Unexpectedly, the film of the present embodiments can have a high content, e.g., wt % of PCR resin. For example, in some embodiments, the PCR resin content of the present films can be about 80% PCR and/or about 100% PCR.
A resin used to make the film of the present embodiments can include an ethylene-based resin. Representative ethylene-based resins that may be used in accordance with the present disclosure include but are not limited to low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), metallocene polyethylene (mPE), very low density polyethylene (VLDPE), ultra-low density polyethylene (ULDPE), polypropylene, ethylene-propylene copolymers, polymers made using a single-site catalyst, ethylene maleic anhydride copolymers (EMAs), ethylene vinyl acetate copolymers (EVAs), polymers made using Zeigler-Natta catalysts, styrene-containing block copolymers, and/or the like, and combinations thereof.
Methods for manufacturing polyolefins are described in The Wiley Encyclopedia of Packaging Technology (Aaron L. Brody et al. eds., 2nd Ed. 1997), which is incorporated by reference herein in its entirety, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail. The density of a polyethylene may be achieved by copolymerizing ethylene with a sufficient amount of one or more monomers. In illustrative embodiments, the monomers are selected from 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, and combinations thereof. Methods for manufacturing polypropylene are described in Kirk-Othmer Concise Encyclopedia of Chemical Technology, pp. 1420-1421 (Jacqueline I. Kroschwitz et al. eds., 4th Ed. 1999), which is incorporated herein by reference, except that in the event of any inconsistent disclosure or definition from the present specification, the disclosure or definition herein shall be deemed to prevail.
In illustrative embodiments, the ethylene-based resin for use in accordance with the present disclosure includes polyethylene. In some embodiments, the polyethylene may be a long chain branching polyethylene, such as a long chain branching LDPE. The polyethylene can be a homopolymer or a copolymer.
When the ethylene-based resin used to make one or more layers includes LDPE, that layer may comprise about 1 wt % LDPE to about 99 wt % LDPE, about 10 wt % LDPE to about 90 wt % LDPE, about 20 wt % LDPE to about 90 wt % LDPE, about 30 wt % LDPE to about 90 wt % LDPE, about 40 wt % LDPE to about 90 wt % LDPE, about 50 wt % LDPE to about 90 wt % LDPE, about 60 wt % LDPE to about 90 wt % LDPE, about 70 wt % LDPE to about 90 wt % LDPE, about 80 wt % LDPE to about 90 wt % LDPE, about 10 wt % LDPE to about 80 wt % LDPE, about 20 wt % LDPE to about 80 wt % LDPE, about 30 wt % LDPE to about 80 wt % LDPE, about 40 wt % LDPE to about 80 wt % LDPE, about 50 wt % LDPE to about 80 wt % LDPE, about 60 wt % LDPE to about 80 wt % LDPE, about 70 wt % LDPE to about 80 wt % LDPE, about 10 wt % LDPE to about 70 wt % LDPE, about 20 wt % LDPE to about 70 wt % LDPE, about 30 wt % LDPE to about 70 wt % LDPE, about 40 wt % LDPE to about 70 wt % LDPE, about 50 wt % LDPE to about 70 wt % LDPE, about 60 wt % LDPE to about 70 wt % LDPE, about 10 wt % LDPE to about 60 wt % LDPE, about 20 wt % LDPE to about 60 wt % LDPE, about 30 wt % LDPE to about 60 wt % LDPE, about 40 wt % LDPE to about 60 wt % LDPE, about 50 wt % LDPE to about 60 wt % LDPE, about 10 wt % LDPE to about 50 wt % LDPE, about 20 wt % LDPE to about 50 wt % LDPE, about 30 wt % LDPE to about 50 wt % LDPE, about 40 wt % LDPE to about 50 wt % LDPE, about 10 wt % LDPE to about 40 wt % LDPE, about 20 wt % LDPE to about 40 wt % LDPE, about 30 wt % LDPE to about 40 wt % LDPE, about 10 wt % LDPE to about 30 wt % LDPE, about 20 wt % LDPE to about 30 wt % LDPE, or about 10 wt % LDPE to about 20 wt % LDPE. In some embodiments, the layer comprises less than about 50% or less than about 40% LDPE. In some embodiments, the layer comprises at least about 60% or at least about 70% LDPE. In some embodiments the LDPE can include Dow 640.
When the ethylene-based resin used to make one or more layers includes HDPE, that layer may comprise about 1 wt % HDPE to about 99 wt % HDPE, about 10 wt % HDPE to about 90 wt % HDPE, about 20 wt % HDPE to about 90 wt % HDPE, about 30 wt % HDPE to about 90 wt % HDPE, about 40 wt % HDPE to about 90 wt % HDPE, about 50 wt % HDPE to about 90 wt % HDPE, about 60 wt % HDPE to about 90 wt % HDPE, about 70 wt % HDPE to about 90 wt % HDPE, about 80 wt % HDPE to about 90 wt % HDPE, about 10 wt % HDPE to about 80 wt % HDPE, about 20 wt % HDPE to about 80 wt % HDPE, about 30 wt % HDPE to about 80 wt % HDPE, about 40 wt % HDPE to about 80 wt % HDPE, about 50 wt % HDPE to about 80 wt % HDPE, about 60 wt % HDPE to about 80 wt % HDPE, about 70 wt % HDPE to about 80 wt % HDPE, about 10 wt % HDPE to about 70 wt % HDPE, about 20 wt % HDPE to about 70 wt % HDPE, about 30 wt % HDPE to about 70 wt % HDPE, about 40 wt % HDPE to about 70 wt % HDPE, about 50 wt % HDPE to about 70 wt % HDPE, about 60 wt % HDPE to about 70 wt % HDPE, about 10 wt % HDPE to about 60 wt % HDPE, about 20 wt % HDPE to about 60 wt % HDPE, about 30 wt % HDPE to about 60 wt % HDPE, about 40 wt % HDPE to about 60 wt % HDPE, about 50 wt % HDPE to about 60 wt % HDPE, about 10 wt % HDPE to about 50 wt % HDPE, about 20 wt % HDPE to about 50 wt % HDPE, about 30 wt % HDPE to about 50 wt % HDPE, about 40 wt % HDPE to about 50 wt % HDPE, about 10 wt % HDPE to about 40 wt % HDPE, about 20 wt % HDPE to about 40 wt % HDPE, about 30 wt % HDPE to about 40 wt % HDPE, about 10 wt % HDPE to about 30 wt % HDPE, about 20 wt % HDPE to about 30 wt % HDPE, or about 10 wt % HDPE to about 20 wt % HDPE. In some embodiments, the layer comprises less than about 40% or less than about 35% HDPE. In some embodiments, the layer comprises at least about 30% or at least about 35% HDPE. In some embodiments the LDPE can include Dow 8007.
When the ethylene-based resin used to make one or more layers includes LLDPE, that layer may comprise about 1 wt % LLDPE to about 99 wt % LLDPE, about 10 wt % LLDPE to about 90 wt % LLDPE, about 20 wt % LLDPE to about 90 wt % LLDPE, about 30 wt % LLDPE to about 90 wt % LLDPE, about 40 wt % LLDPE to about 90 wt % LLDPE, about 50 wt % LLDPE to about 90 wt % LLDPE, about 60 wt % LLDPE to about 90 wt % LLDPE, about 70 wt % LLDPE to about 90 wt % LLDPE, about 80 wt % LLDPE to about 90 wt % LLDPE, about 10 wt % LLDPE to about 80 wt % LLDPE, about 20 wt % LLDPE to about 80 wt % LLDPE, about 30 wt % LLDPE to about 80 wt % LLDPE, about 40 wt % LLDPE to about 80 wt % LLDPE, about 50 wt % LLDPE to about 80 wt % LLDPE, about 60 wt % LLDPE to about 80 wt % LLDPE, about 70 wt % LLDPE to about 80 wt % LLDPE, about 10 wt % LLDPE to about 70 wt % LLDPE, about 20 wt % LLDPE to about 70 wt % LLDPE, about 30 wt % LLDPE to about 70 wt % LLDPE, about 40 wt % LLDPE to about 70 wt % LLDPE, about 50 wt % LLDPE to about 70 wt % LLDPE, about 60 wt % LLDPE to about 70 wt % LLDPE, about 10 wt % LLDPE to about 60 wt % LLDPE, about 20 wt % LLDPE to about 60 wt % LLDPE, about 30 wt % LLDPE to about 60 wt % LLDPE, about 40 wt % LLDPE to about 60 wt % LLDPE, about 50 wt % LLDPE to about 60 wt % LLDPE, about 10 wt % LLDPE to about 50 wt % LLDPE, about 20 wt % LLDPE to about 50 wt % LLDPE, about 30 wt % LLDPE to about 50 wt % LLDPE, about 40 wt % LLDPE to about 50 wt % LLDPE, about 10 wt % LLDPE to about 40 wt % LLDPE, about 20 wt % LLDPE to about 40 wt % LLDPE, about 30 wt % LLDPE to about 40 wt % LLDPE, about 10 wt % LLDPE to about 30 wt % LLDPE, about 20 wt % LLDPE to about 30 wt % LLDPE, or about 10 wt % LLDPE to about 20 wt % LLDPE. In some embodiments, the layer comprises less than about 40% or less than about 35% LLDPE. In some embodiments, the layer comprises at least about 10% or at least about 20% LLDPE. In some embodiments the LLDPE can include EM 3518.
In some embodiments, the ethylene-based resin includes a layer comprising a blend of polymers. In illustrative embodiments, such a layer can include a blend of at least two or at least three polymers. In some embodiments, a layer can include a blend of at least two or at least three polyolefins. In some embodiments, a layer can include a blend of at least two or at least three polyethylenes.
An exemplary resin can include a linear low-density polyethylene (LLDPE) Repro grade resin, e.g., EM 3518 or Ecowise (PCR Ecowise LLDPE). The feedstock for these resins can include recycled materials from grocery stores, supermarkets, warehouses, distribution centers and the like. An amount of the PCR Ecowise LLDPE in the formulation of the film of the present embodiments can be approximately in a range from about 10 wt % to about 20 wt % and/or approximately in a range from about 10 wt % to about 15 wt %. A person of ordinary skill in the art would expect an end application of the films made from this resin may include plastic bags, which gauge range from 0.6 mil to 2 mil, or solid plastic, plastic-wood decking, and floor applications.
Another exemplary resin can include a KWR105M2KW HDPE grade from KW Plastics. The feedstock for these resins can come from bulky rigids, which includes waste carts, pails, crates, bins, and so forth. A person of ordinary skill in the art would expect an end application may include injection molded products. In some embodiments, increasing an amount of HDPE can increase an overall density of the film.
Various properties of the above-listed resins and their ingredients may be found in Technical Data Sheets that correspond to each compound, the Technical Data Sheets being publicly available information as recognized by one skilled in the art and the contents thereof being incorporated herein by reference in their entireties.
An amount of PCR resin used to make the film of the present embodiments can vary. For example, in some embodiments, the film can be made with about 80% post-consumer recycled resin. Alternatively, in some embodiments, the film can be made with about 100% post-consumer recycled resin. As mentioned above, in some embodiments, performance of a PCR resin in formation of films can be less favorable than virgin plastic resin due to one or more factors. For example, the PCR resin can undergo degradation, which can produce a film that degrades more quickly. After each recycling process, polymer chains can undergo degradation resulting in chain scission, e.g., breaking of a large polymer chain into smaller chains, which can result in poor mechanical properties. Moreover, polymer chains can undergo crosslinking after recycling, which causes several chains to react with others producing a gel-like network that can also result in the loss of mechanical properties. Additionally, for cross-linked polymer chains, the gels can pose processing challenges as they can form holes or adversely affect the aesthetic of a finished product.
PCR resins can also be contaminated which can lead to poorer performance in films. For example, PCR resins can experience cross-contamination with other polymers with the incompatibility between the recycled polymers leading to formation of materials with poor properties. In some embodiments, the PCR resins can be contaminated with one or more foreign objects, e.g., glue, paper, wood, and so forth. A person skilled in the art will recognize that the presence of a foreign contaminant can also reduce one or more desirable properties of the PCR resin and/or make the PCR resin unusable for film formation.
As noted above, unexpectedly, the films of the present embodiments can outperform virgin resins despite their high PCR resin content, e.g., 80% PCR resin and/or 100% PCR resin films. It is believed, without being limited by this theory, that this outperformance can be attributed to the blend of polymers of different molecular weights used in the present resins. For example, the blend of polymers used herein can impart superior toughness properties to the resins, which result in superior breathability, Elmendorf tear strength, trapezoidal tear strength, and mocon values. The details and measurements of the present resins are discussed in greater detail below.
A film forming apparatus 10 that is suitable for forming the presently disclosed films is shown, for example, in
The casting/drawing section 12 comprises an extruder 24 followed by at least one chill roller 28 with a first gap 26 therebetween. The position of extruder 24 relative to chill roller 28 may vary from that shown in
The webs, or films, of the present embodiments may be formed by a variety of suitable means, and may be cast, blown, calendered, mono-extruded, co-extruded, chill cast, nip embossed, or any other suitable method which would result in a film compatible with the process described herein.
In one embodiment, the thermoplastic polymeric film formulation may be blended in the extruder 24, for example at a temperature of from about 210° C. to about 280° C. The exact temperature will depend upon the formulation of the polymeric compositions. The web, or melt curtain, comprising the polymeric composition may be extruded (or coextruded if a multilayer film is being formed) onto the chill roller 28. The film 15, as it leaves the chill roller 28, can be stretched to the desired thickness without significant MD molecular orientation. In some embodiments, at least two chill rollers can be present, with the speeds and temperatures of the chill rollers each may be the same or different, but will be sufficient for the film to be stretched to the desired thickness without significant MD molecular orientation, yet below the melting temperature of the polymeric composition. By way of non-limiting example only, the temperatures may differ by 5° C., by 10° C., or more. The chill rollers may each individually be smooth, textured, coated (e.g., with a release treatment), which may be the same or different on each roll.
The length of first gap 26 between the extruder 24 and chill roller 28 may be the shortest distance between the extruder 24 and the chill roller 28, and may be greater than previous cast MDO processes. In one embodiment, the length of the first gap 26 is greater than 2.5 cm, alternatively is from about 2.5 cm to about 25 cm, alternatively is from about 3 cm to about 15 cm, and alternatively is from about 3 cm to about 7.6 cm. The extrudate may undergo a melt curtain stretch, with a corresponding reduction in thickness, in gap 26 of from 10 times to about 25 times (about 10× to about 25×).
In one embodiment, the apparatus may include an additional roller and a nip between the extruder 24 and the chill roller 28, as depicted in U.S. Pat. No. 7,442,332. In another embodiment, the apparatus may include one or more additional chill rollers. In yet another embodiment, chill roller 28 may be replaced by two rollers, wherein the rollers form an additional nip. The rollers may be a metal roller and a rubber roller, and the metal roller optionally may be embossed. After passing through the additional nip, the film is advanced through nip 33 and further through the process described herein.
The length of the second gap 32 between the chill roller 28 and the nip 33 at the stretching roller 30 is the shortest distance between the chill roller 28 and the stretching roller 30, and in one embodiment is at least about 7.5 cm, alternatively is from about 7.5 to about 30 cm, alternatively is from about 7.5 to about 20 cm, alternatively is from about 7.5 cm to about 10 cm, alternatively is about 30 cm, alternatively is about 20 cm, alternatively is about 15 cm, alternatively is about 15 cm, and alternatively is less than 10 cm. The film 15, after being stretched between chill roller 28 and stretching roller 30, is essentially a nonporous film having limited molecular orientation in the MD.
Herein, “imparting limited machine direction orientation to the film” means to produce sufficient MD orientation to give the film an MD load at break of at least 2.0 N/cm with a CD load at break of at least 0.7 N/cm. In addition, the film will have a ratio of MD load at break to CD load at break of from about 1 to about 15. Although the amount of MDO may not be directly quantifiable, the amount of MDO correlates to the properties of the film. A film that has limited MDO will have, in particular, improved CD properties, such as CD Elmendorf and Trapezoidal tear strength, CD tensile strength at break, and an improved balance of CD and MD tensile strengths relative to previously described films.
Downstream from casting/drawing section 12, the film 15 may pass from stretching roller 30 around idle roller 39 to a first machine direction orientation (MDO) section 14. The purpose of this section is to further stretch the film in the machine direction while still avoiding significant MD orientation.
As would be understood by one of skill in the art, the number of stretching rollers, heated rollers and chill rollers within first MDO section 14 may vary, as well as the number of MDO sections. Thus, in an alternative embodiment, the apparatus may comprise one or more additional sets of stretching rollers, heated rollers, and/or cooling rollers to impart desired physical and aesthetic characteristics, such as porosity and opacity. By way of example, a second set of heated rollers, stretching rollers and/or cooling roller may be located in first MDO section 14, downstream from stretching rollers 36a and 36b and upstream from cooling roller 37. In an alternative embodiment, a second set of heated rollers, stretching rollers and/or cooling roller are located downstream from CDI section 16 in a second MDO section.
Cross direction interdigitated roller (CDI) section 16, if present, may include a tensioning roller 38 followed by interdigitating rollers 40, 42. In the present embodiments, interdigitating rollers 40, 42 are designed to stretch the film in the cross direction, resulting in additional film activation and imparting breathability. In one embodiment, machine direction interdigitating rollers are used in place in of, or in addition to, cross direction interdigitating rollers 40, 42, either before or after CDI section 16. Suitable cross direction interdigitated rollers are described in U.S. Pat. No. 7,442,332.
In place of MDO section and or CDI section or in addition to these sections, the film can be stretched using a tentering frame (not shown). This can be used to effect both MDO and CDO.
The film 15 may move from the CDI section 16 to other optional components, including but not limited to, a corona treatment section, an annealing section, a second MDO section and/or a winder, where it is then ready for its intended use. The films and/or laminates of the present disclosure are suitable for use as pouches for packaging, wrapping products such as personal hygiene items, as well as foods such as sandwiches, fruits, vegetables and the like, breathable poly bags such as breathable diaper poly bags. In the case of personal hygiene products, the present films can be used in disposable absorbent products. Some further non-limiting examples include diapers, training pants, adult incontinence pads and pants, swimwear, sanitary napkins, tampons, panty liners, etc. In one embodiment, the films can be related to an absorbent article comprising the films described herein. In one embodiment, the absorbent article is a diaper.
The present disclosure further describes laminates comprising the films of the present embodiments. The laminates comprise a first layer comprising the breathable, thermoplastic films described herein, and a substrate attached to one or both surfaces of the film. The substrate may be any woven or a nonwoven material suitable for use with thermoplastic films, and in one embodiment is a spunbond nonwoven. The substrate may have a basis weight of 100 gsm or less, alternatively 50 gsm or less, alternatively 25 gsm or less, alternatively 20 gsm or less, alternatively 15 gsm or less, and alternatively 10 gsm or less. In some embodiments, the substrate may have a basis weight approximately in a range of about 10 gsm to about 20 gsm, approximately in a range of about 12 gsm to about 18 gsm, and/or approximately in a range of about 13 gsm to about 15 gsm. The substrate may be attached to the film by a variety of means such as adhesive lamination, ultrasonic bonding, extrusion bonding, etc.
The importance of some testing values can vary based on the use application. For example, in embodiments in which the films and/or laminates of the present disclosure are used in items such as diapers, the present films and/or laminates can be used in diaper backsheets or ears (closure tabs). In such embodiments, machine calculations can be performed to evaluate how much stretching is experienced by the film, e.g., determining the load at each point. Specifically, stretching in the cross-direction (CD) and machine direction (MD) can be evaluated, with superior stretching in the CD being preferred as the closure tabs of diapers are routinely stretched in the cross-direction as opposed to the MD during use. It will be appreciated however that for alternate applications, MD stretching performance can be preferred when the use of the films and/or laminates is routinely stretched in the MD.
Additional measurements taken to evaluate performance of the films and/or laminates can include mass at break, e.g., the load taken to break the film and/or laminate, Elmendorf tear strength, and trapezoidal tear strength. Tear strength or tear force, reflects the ease or difficulty by which the film can be torn, and is expressed in units of grams. Herein, tear strength may be measured by the Elmendorf notched tear test, ASTM D-1922, incorporated herein by reference and/or by the trapezoidal tear test (trap test), as described herein or according to ASTM D-5587. The test may be performed with either a notched or an unnotched film and in either the CD or MD direction. Unless otherwise specified, herein tear strength is notched tear strength. It is noted that tear strength is related to film thickness, and any comparison of tear strengths must take into account the relative basis weights of the comparative samples.
The films of the present embodiments can have an Elmendorf tear strength in the machine direction of at least about 5 g, alternatively of at least about 10 g, alternatively of at least about 15 g, alternatively of at least about 25 g, alternatively of at least about 50 g, alternatively from about 5 g to about 50 g, alternatively from about 10 g to about 45 g, and alternatively from about 15 g to about 40 g. The films of the present embodiments can have an Elmendorf tear strength in the cross direction of at least about 25 g, alternatively of at least about 50 g, alternatively of at least about 75 g, alternatively of at least about 150 g, alternatively of at least about 250 g, alternatively from about 25 g to about 250 g, alternatively from about 50 g to about 200 g, and alternatively from about 100 g to about 175 g. In some embodiments, the Elmendorf tear strength of the breathable film in the cross direction can be about three times larger than the Elmendorf tear strength of the one or more layers in the machine direction, as discussed below.
The films of the present embodiments can have a trapezoidal (“trap”) tear strength in the machine direction of at least about 200 g, alternatively of at least about 300 g, alternatively of at least about 350 g, alternatively of at least about 400 g, alternatively of at least about 500 g, alternatively of at least about 750 g, alternatively of at least about 100 g, alternatively from about 200 g to about 1000 g, alternatively from about 250 g to about 750 g, and alternatively from about 300 g to about 600 g. The films of the present embodiments can have a trap tear strength in the cross direction of at least about 300 g, alternatively of at least about 400 g, alternatively of at least about 500 g, alternatively of at least about 600 g, alternatively of at least about 800 g, alternatively from about 300 g to about 800 g, alternatively from about 400 g to about 750 g, and alternatively from about 500 g to about 600 g. In some embodiments, the trapezoidal tear strength of the breathable film in the cross direction can be about 1.9 times larger than the trapezoidal tear strength of the one or more layers in the machine direction, and/or the trapezoidal tear strength of the breathable film in the cross direction can be about two times larger than the trapezoidal tear strength of the one or more layers in the machine direction, as discussed below.
The present embodiments will be further appreciated in light of the following detailed examples.
The following examples are set forth for purposes of illustration only. Parts and percentages appearing in such examples are approximate unless otherwise stipulated.
A number of films were formed according to the previously described method. The polymeric formulation of the PCR resins in the film of the present embodiments may include a combination of one or more raw ingredients. In exemplary embodiments, the formulation may include CF7030PE=70% FL 500 CaCO3, 29.85% EM 3518 LLDPE and 0.15% anti-oxidant package; HC950PE=72% FL 500 CaCO3, 21.85% Dow 2036.01G LLDPE, 6% TiO2 and 0.15% anti-oxidant package; and PCR Compound=70% FL 500 CaCO3, 29.8% Ecowise LLDPE and 0.2% anti-oxidant package, which are present in the percentages presented in Table 1, reproduced below:
Formation of the films of the present embodiments can occur by combining one or more of the raw ingredients discussed above. For example, the CF7030PE can be compounded to create the resin of the present embodiments and/or outsourced to a third party supplier. Once this resin is compounded, the compounded resins can be placed into an extruder and passed to the hopper for extrusion on a lab line. In some embodiments, the breathable film can be manufactured in two steps. First, the raw ingredients discussed above can be extruded on Killion manufacturing line to make precursor films. The extruder can be run at different line speeds to change the basis weight of the films. Once the films are formed, the films can be put in the CDI unit to stretch the film in the CD direction to create breathability. The remaining raw ingredients can be added to the film formation via the techniques discussed above. As noted above, various properties of the above-listed ingredients may be found in Technical Data Sheets that correspond to each compound, with the Technical Data Sheets being publicly available information as recognized by one skilled in the art and the contents thereof being incorporated herein by reference in their entireties.
Table 1 illustrates exemplary formulations of a control film (control) compared to films manufactured with 100% PCR resin (PCR form 1, PCR form 2), and 80% PCR resin (PCR form 3). The LLDPE (EM3518), the HDPE (DOW 8007), and the LDPE (DOW 640), which are discussed above are also presented in the presented percentages. It will be appreciated that the percentages are presented in terms of weight percent where a total weight of the film is 100 wt %.
The 100% PCR resin films can include a total filler of 42 wt % and a total polymer phase of 58 wt %, in which the total PCR resin phase is 58 wt %, which accounts for a total PCR in the polymer phase of 100% in the 100% PCR resin film. The control film has a total PCR in the polymer phase of 0% and the 80% PCR resin film has a total PCR in the polymer phase of approximately 82%.
As shown, the control film can include EM 3518 as the LLDPE, which is omitted from the 100% PCR resin and the 80% PCR resin films, with these films containing PCR Ecowise LLDPE. The difference in formulations can occur due to PCR Ecowise LLDPE having a density of less than 0.92, which resulted in EM 3518 being used in making control film.
MD tensile elongation at break percentages for these films can suggest a different outcome. For example, as shown in
MD tensile load at 5%, 10%, and 25% break for each of the films are shown in
CD tensile elongation at break percentages for these films can suggest a different outcome. For example, as shown in
CD tensile load at 5%, 10%, and 25% break for each of the films are shown in
The following numbered clauses include embodiments that are contemplated and non-limiting:
This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 63/434,525, filed on Dec. 22, 2022, which is expressly incorporated by reference herein.
Number | Date | Country | |
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63434525 | Dec 2022 | US |