Patent Application
20250196483
Today, a huge amount of polypropylene films exists as possible recycle from various end-user application. However, other than downgrading, it is generally not possible to reuse recycled scraps as materials biaxially oriented polypropylene (“BOPP”) films, such as packaging films. Due at least partially to high technical and quality demands for raw materials used in oriented films, use of recycled polypropylene, such as polypropylene post-consumer (“PP-PCR”) and/or polypropylene post-industry (“PP-PIR”) was difficult, at best. Many plastics often impact the environment in detrimental ways, including, for instance, trash production and increased emission of carbon dioxide during processing. As a result, it is a great challenge to re-think the re-use of plastics in general in order to reduce the environmental impact of the waste residues resulting from the use of polypropylene in many applications. In the ensuing pages, disclosed are example embodiments of BOPP films and labels comprising PP-PCR and/or PP-PIR with selected quality properties for various applications, e.g., packaging, in-mold labeling, pressure-sensitive labeling, wrap-around labeling that at least mitigate optical defects, process stability, and/or other issues in the art.
PP-PCR resins are available in the market, but because of high heterogeneity among sources, as well as the chemical and mechanical damages that the plastic suffers in its entire chain, i.e., from production to waste, the properties of those PP-PCR resins are generally poor, and, thus, a challenge to reuse them in many applications, which require high property standards.
PP-PCR is made from a material generated as waste, e.g., packaging waste, single-use garments, clinical scraps (syringes, infusion bags . . . ), by households, industry, or commerce (in their role as end-using consumers); the resulting recyclates, i.e., recycled materials, are referred to post-consumer recyclates (“PCR”). PP-PCR may be recycled in many ways. For purposes of discussion regarding the disclosed films and labels, PP-PCR is recycled into a resin, which is then used in general for less demanding applications (downgrading). This provides these recycled scraps a second life, which significantly reduces the amount of plastic waste in the environment. Manufacturers in general produce PP-PCR by mechanical recycling from pre-selected scraps using, for instance, the following process steps: grinding the scraps into flakes, washing the flakes, drying the washed flakes, and re-granulating the dried flakes by melting and/or extruding step(s) to yield PP-PCR granules.
PP-PIR is made from polypropylene generated as waste in the converting industry of the PP (e.g., BOPPP) film and/or labels. These converters, for example, include coating, printing and/or packaging facilities. Their scrap products have not been used finally by the end consumer, and, thus, are not PP-PCR. The scraps, for example, might result from cutting edges, portions of transition reels, or off-grade produced in the converting step of the packaging film.
Internal reclaim (“IR”) is recycled polypropylene scrap resulting during the production of the BOPP film, itself, and accumulating in the production facility in place before leaving the production site for further converting steps. Accordingly, use of “reclaimed PP” in this disclosure should be understood to be PP-PCR and/or PP-PIR, whether alone or in combination with any other type of reclaim, including IR, for optionally mixing with virgin reclaim and/or non-recycled polymers, including PP, whether homopolymers, copolymers and/or terpolymers of any type.
Polymer-based plastics may be used today to manufacture a varied range of articles, including films, molded products, foams, bottles, bags, tissues, and more with particular characteristics. In relation to polypropylene, downgrading of the end-of-use scraps is possible for low-quality products having unpredictable properties.
Virgin polypropylene has many beneficial values in production and manufacture of polypropylene films. But, plastics often impact the environment in detrimental ways including trash production and increased emission of CO2 during processing. So it is a great challenge for producers and end users to think about the use and re-use of plastics to reduce the environmental impact of the waste residues.
In one example embodiment is an oriented film comprising at least one layer comprising ≥about 5 wt. % through ≤about 95 wt. % of a combination of virgin polypropylene and reclaimed polypropylene, and has a melt flow index from about 0.5 g/min through about 15 g/min and a dispersion index from about 2 through 10. Further, the filter pressure of the oriented film's post-industrial reclaimed polypropylene is ≤about 20 bar/kg when using a 350-mesh filter on a COLLIN Teach Line Type FT-E20T extruder according to the method and settings in this description as such films are commercially stable. In other example embodiments, the filter pressure of the oriented film's post-industrial reclaimed polypropylene is ≤about 30 bar/kg or even ≤about 50 bar/kg to result in commercially stable films and labels. The total thickness of the disclosed films and labels may be ≤about 15 μm, ≤about 20 μm, ≤about 25 μm, ≤about 50 μm, or even ≤about 100 μm in various embodiments.
Below, directional terms, such as “above,” “below,” “upper,” “lower,” “front,” “back,” “top,” “bottom,” etc., are used for convenience in referring to the accompanying drawings. In general, “above,” “upper,” “upward,” “top,” and similar terms refer to a direction away the earth's surface, and “below,” “lower,” “downward,” “bottom,” and similar terms refer to a direction toward the earth's surface, but is meant for illustrative purposes only, and the terms are not meant to limit the disclosure.
Various specific embodiments, versions and examples are described now, including exemplary embodiments and definitions that are adopted herein for purposes of understanding. While the following detailed description gives specific preferred embodiments, those skilled in the art will appreciate that these embodiments are exemplary only, and that the disclosure can be practiced in other ways. For purposes of determining infringement, the scope of the invention will refer to the any claims, including their equivalents, and elements or limitations that are equivalent to those that are recited.
As used herein, “polymer” may be used to refer to homopolymers, copolymers, interpolymers, terpolymers, etc. Likewise, a “copolymer” may refer to a polymer comprising two monomers or to a polymer comprising three or more monomers.
As used herein, “elastomer” is defined as a propylene-based or ethylene-based copolymer that can be extended or stretched with force to at least 100% of its original length, and upon removal of the force, rapidly (e.g., within 5 seconds) returns to its original dimensions.
As used herein, “plastomer” is defined as a propylene-based or ethylene-based copolymer having a density in the range of 0.850 g/cm3 to 0.920 g/cm3 and a DSC melting point of at least 40° C.
As used herein, “intermediate” is defined as the position of one layer of a multilayered film, wherein said layer lies between two other identified layers. In some embodiments, the intermediate layer may be in direct contact with either or both of the two identified layers. And/or in other embodiments, additional layers may also be present between the intermediate layer and either or both of the two identified layers.
As used herein, “substantially free” is defined to mean that the referenced film layer is largely, but not wholly, absent a particular component. In some embodiments, small amounts of the component may be present within the referenced layer as a result of standard manufacturing methods, including recycling of film scraps and edge trim during processing.
By “consist essentially of,” what is meant, for example, is that a particular film layer does not have any more than 1 wt. % or 2 wt. % or 3 wt. % or 4 wt. % or 5 wt. % of other polymers in the bulk material constituting the film layer's composition, but “consist essentially of” does not exclude the possibility that the particular film layer also has additives, such as anti-slip agents, anti-blocking agents, anti-oxidants, pigments, whitening agents, cavitation agents, etc. regardless of what polymers or other materials make up the additive(s).
As used herein, “about” means the number itself and/or within 5% of the stated number. For instance, with about 5%, this means 5 and/or any number or range within the range of 4.75 to 5.25, e.g., 4.75 to 4.96, 4.81 to 5.1, etc.
Turning towards an overview of the disclosed films and labels before turning further to details, a filter pressure test involving filter mesh and pressure increase was used to evidence that films and labels, whether biaxially or monoaxially oriented, could contain reclaimed PP that resulted in “stable productions” as defined herein. Surprisingly, reclaimed-PP-containing films showed a filter pressure increase at a mesh above the film's final film thickness may be used. In various embodiments, the reclaimed-PP-containing films and labels may be mono- or co-extrusion two-, three-, four-, five-layered, or more. And, the reclaimed-PP-containing films and labels may have the reclaimed-PP in the core layer and/or one or more tie layers. Filter pressure values ≥50 bar/kg produce films with more film breaks, quality issues, and are generally commercially unacceptable films, and this is why this disclosure teaches use of 50 bar/kg or below as it is surprisingly possible to make upgraded products therefrom instead of relegating use into a downgraded product or not used at all, i.e., garbage. As a result, this invention solves a problem by improving the lifecycle (i.e., birth to bin) of PP-PIR film.
In various embodiments, the disclosure provides an oriented film, methods, and labels having at least one layer comprising ≥about 5 wt. % through ≤about 95 wt. % of a combination of virgin polypropylene and reclaimed polypropylene, wherein the reclaimed polypropylene—whether homopolymer (e.g., iPP, sPP, etc.), PP copolymer(s), oriented or non-oriented, etc., and combinations thereof—has a melt flow index from about 0.5 g/min through about 10 g/min and a dispersion index from about 2 through 10, wherein filter pressure of the reclaimed polypropylene ≤about 50 bar/kg when using a 350-mesh filter on a COLLIN Teach Line Type FT-E20T extruder according to the method and settings as further described below in this description.
In various example embodiments, reclaimed-PP-containing films and labels had at least one layer comprising, consisting essentially of, or consisting of a PP-PCR and/or PP-PIR polymer composition or combination thereof, wherein its reclaimed-PP content may vary from greater than or equal to about 5 wt. % through greater than or equal to about 95 wt. %—and any range in between that minimum and maximum without reciting each and every possible range, e.g., about 6 wt. % to about 12 wt. %, about 23 wt. % through about 67 wt. %, etc.—in combination with: (1) a virgin-PP-containing polymer resin content varying from greater than or equal to about 5 wt. % through greater than or equal to about 95 wt. %—and any range in between that minimum and maximum without reciting each and every possible range; and (2) optionally, additives, such as those named later in this disclosure. The virgin PP-containing polymer may be selected from PP homopolymers (e.g., iPP, sPP, etc.), PP copolymer(s), and combinations thereof. The reclaimed-PP-containing films and labels resulted in stable productions, wherein a “stable production” means no web breaks on a BOPP tenter manufacturing tenter line run anywhere from 50 through 600 m/min at a temperature from 80 through 180° C., with a web width anywhere between 1.5 through 10 m, over a time period of about 1.5 h. In some embodiments, this may result in the disclosed films having a filter pressure of ≤30 bar/kg, in other embodiments ≤40 bar/kg, in other embodiments, and ≤50 bar/kg.
A COLLIN Teach Line Type FT-E20T extruder was used in measuring filter pressure increase of the reclaimed PP grades. Granular reclaimed-PP was melted in the extruder, homogenized, and conveyed. The gear pump conveyed the melt at a constant throughput through a sieve, having different mesh sizes, and filter. The contaminants in the reclaimed-PP that are larger than the meshes of the sieve are retained, and, thereby, create an increase in pressure before the filter. The pressure curve from the beginning to the end of the filter test is recorded by means of the evaluation software and the pressure increase is recorded over time. The pressure increase is directly related to the number and size of the retained contaminants in the reclaimed-PP, i.e., contamination/particle size distribution. To state the foregoing discussion by a formula:
Below are more examples of reclaimed-PP-containing films and labels. In Table 1, presented are tested reclaimed-PP films and their filter pressure values, wherein the last three columns are in bold font to show that these films were stable productions. The melt flow indices (ASTM D1238, 230° C., 2.16 kg) of the reclaimed-PP in the last five columns may be from 0.5 through 15 g/10 min, and their dispersion indices, which equals <Mw>/<Mn>, may be from 2 through 10.
Turning now to further example embodiments, below are exemplary label films in accordance with this disclosure produced on a BOPP pilot line using the different PP-PCR grades. Reference 1 is a standard BOPP white-voided label film, which one in application may be used in a wrap-around/reel-fed application. Reference 1 does not contain any reclaimed PP. The table immediately below provides more details about Reference 1. The homopolypropylene (hPP) used in all examples of this disclosure was Moplen HP525J (LyondelBasell MFI=3.0, Filter Pressure DTW 45S<0.1 bar/kg). However, in other embodiments, different types of PPs than found in any of the examples' layers below, including hPP, iPP, sPP, PP copolymers, or combinations thereof, may be used as a replacement to this hPP without departing from the invention so long as these PP polymers abide by the melt and polyolefin dispersity indices mentioned in the preceding paragraph. And, no matter the type of PP of the reclaimed PP in the disclosed oriented films herein—both monoaxially and biaxially, and whether or not each of the at least one layer(s) of the oriented film comprised, consisted essentially or consisted of reclaimed PP, i.e., optionally in combination with additives and/or virgin PP compositions—it was determined that when the filter pressure of the reclaimed polypropylene is ≤about 50 bar/kg when using a 350-mesh filter on a COLLIN Teach Line Type FT-E20T extruder according to the method and settings stated in this description, then a stable production of the oriented film, whether a film or label, resulted.
C/R stands for cast roll and W/B stands for water bath in this skin/tie/core/tie/skin layer structure.
Example 1 immediately below is an example BOPP label film, which in one application may be used in a wrap-around/reel-fed application, and contains about 36 wt. % of PP-PCR in the base layer (also known as “core layer”). If PP-PCR-2, PP-PCR-3, or PP-PCR-4 from Table 1 is used for PP-PCR #in the structure below, then the production line also shows stable production, i.e., commercial quality results. Using PP-PC-1, no stable production occurs and poor film quality is observed, and only borderline film productions occur with Borealis PP-PCR-1 and Borealis PP-PCR-2. Using PCR Total rPPH03GR, there is no production possible.
In other examples embodiments of Example 1, the wt. % of “PP-PCR #”, i.e., PP-PCR-3, -4, or combination thereof (and used to mean that hereinafter), may be any individual or combined wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset), and the cavitating agent, whether BASF B2550FC (i.e., PBT, or a different organic or inorganic, such as CaCO3, wherein the cavitating agent is optionally in a polymer matrix, such as PP or a different polymer) may be any wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset). Accordingly, the weight percentages of the compositions in the core layer vary with the remaining balance of the core layer being the hPP, as defined in paragraph [0019], optionally in combination with one or more other additives. In various embodiments of the foregoing core layer description of Example 1, the tie layers may include a pigmenting agent, whether Ampacet White 70A (i.e., TiO2 or different pigment(s), wherein the pigmenting agent is optionally in a polymer matrix, such as PP or a different polymer) and may be any wt. % within a wt. % range from about 0.5 wt. % through about 15 wt. % (i.e., and any subset range therebetween without stating each possible subset), optionally in combination with one or more other additives. Each of the skins may be the same or different in composition, and each of the skins may comprises, consist essentially of or consists of any copolymer or terpolymer comprising carbons from C1-C8, optionally in combination with one or more additives.
Example 2 immediately below is a BOPP label film, which in one application may be used in a wrap-around/reel-fed application, and contains about 36 wt. % of PP-PCR-3 or -4 and about 20 wt. % PP-IR in the base layer. Using this formulation, the production line shows stable production. Here and elsewhere in this disclosure, PP-IR may vary, but in some embodiments, could be acrylic coated PP film, EVOH-coated PP film, uncoated PP, etc.
In other examples embodiments of Example 3, the wt. % of PP-PCR #, i.e., PP-PCR 3, 4, or combination thereof, may be any individual or combined wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset), the PP-IR may be any wt. % within a wt. % range from about 2 wt. % through about 35 wt. % (i.e., and any subset range therebetween without stating each possible subset), and the cavitating agent, whether BASF B2550FC (i.e., PBT, or a different organic or inorganic, such as CaCO3, wherein the cavitating agent is optionally in a polymer matrix, such as PP or a different polymer) may be any wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset). Accordingly, the weight percentages of the compositions in the core layer vary with the remaining balance of the core layer being the hPP, as defined in paragraph [0019], being at least about 20 wt. %, optionally in combination with one or more other additives. In various embodiments of the foregoing core layer description of Example 1, the tie layers may include a pigmenting agent, whether Ampacet White 70A (i.e., TiO2 or different pigment(s), wherein the pigmenting agent is optionally in a polymer matrix, such as PP or a different polymer) and may be any wt. % within a wt. % range from about 0.5 wt. % through about 15 wt. % (i.e., and any subset range therebetween without stating each possible subset), optionally in combination with one or more other additives. Each of the skins may be the same or different in composition, and each of the skins may comprises, consist essentially of or consists of any copolymer or terpolymer comprising carbons from C1-C8, optionally in combination with one or more additives.
Reference 2 immediately below is a standard BOPP label film, which in one application may be used in a pressure sensitive label application, and does not contain any reclaimed PP.
Reference 2—White Voided PSL-Film in 58LH242 (d: 0.73, FG: 23.6 g/m2)
Example 3 immediately below is BOPP label film, which in one application may be used in a pressure sensitive label application, and contains 37 wt. % of the PCR in the base layer. If PP-PCR-3 or PP-PCR-4 mentioned in Table 1 is used, the production line shows stable production. If PP-PCR 1 is used, no stable production does not occur, and only borderline film production occurs with PP-PCR-2. Using the PCR Total rPPH03GR, no production is possible.
In other examples embodiments of Example 3, the wt. % of PP-PCR #, i.e., PP-PCR-3, -4, or combination thereof, may be any individual or combined wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset), and the cavitating agent, whether BASF B2550FC (i.e., PBT, or a different organic or inorganic, such as CaCO3, wherein the cavitating agent is optionally in a polymer matrix, such as PP or a different polymer) may be any wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset). Accordingly, the weight percentages of the compositions in the core layer vary with the remaining balance of the core layer being the hPP, as defined in paragraph [0019], with the hPP in the core layer being as high as 80 wt. %, optionally in combination with one or more other additives. In various embodiments of the foregoing core layer description of Example 1, the tie layers may include a pigmenting agent, whether Ampacet White 70A (i.e., TiO2 or different pigment(s), wherein the pigmenting agent is optionally in a polymer matrix, such as PP or a different polymer) and may be any wt. % within a wt. % range from about 0.5 wt. % through about 15 wt. % (i.e., and any subset range therebetween without stating each possible subset), optionally in combination with one or more other additives. Each of the skins may be the same or different in composition, and each of the skins may comprises, consist essentially of or consists of any copolymer or terpolymer comprising carbons from C1-C8, optionally in combination with one or more additives.
Example 4 immediately below is BOPP label film, which in one application may be used in a pressure sensitive label application, and contains 37 wt. % of PP-PCR 3 or 4 and 20% IR in the base layer. Using this formulation, the production line shows stable production.
In other examples embodiments of Example 4, the wt. % of PP-PCR #, i.e., PP-PCR-3, -4, or combination thereof, may be any individual or combined wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset), the PP-IR may be any wt. % within a wt. % range from about 2 wt. % through about 35 wt. % (i.e., and any subset range therebetween without stating each possible subset), and the cavitating agent, whether BASF B2550FC (i.e., PBT, or a different organic or inorganic, such as CaCO3, wherein the cavitating agent is optionally in a polymer matrix, such as PP or a different polymer) may be any wt. % within a wt. % range from about 5 wt. % through about 60 wt. % (i.e., and any subset range therebetween without stating each possible subset). Accordingly, the weight percentages of the compositions in the core layer vary with the remaining balance of the core layer being the hPP, as defined in paragraph [0019], being at least about 20 wt. %, optionally in combination with one or more other additives. In various embodiments of the foregoing core layer description of Example 1, the tie layers may include a pigmenting agent, whether Ampacet White 70A (i.e., TiO2 or different pigment(s), wherein the pigmenting agent is optionally in a polymer matrix, such as PP or a different polymer) and may be any wt. % within a wt. % range from about 0.5 wt. % through about 15 wt. % (i.e., and any subset range therebetween without stating each possible subset), optionally in combination with one or more other additives. Each of the skins may be the same or different in composition, and each of the skins may comprises, consist essentially of or consists of any copolymer or terpolymer comprising carbons from C1-C8, optionally in combination with one or more additives.
Reference 3 immediately below is a transparent standard BOPP label film, which in one application may be used in a packaging or tape application, and does not contain any reclaimed PP.
Example 5 immediately below is a transparent standard BOPP film, which in one application may be used in a packaging or tape application, and contains 50 wt. % of PP-PIR in the base and tie layers, and in alternate, example embodiments, the core and/or tie layers may comprise, consists essentially of, or consists of: (1) from about 30 wt. % through about 70 wt. % of PP-PIR, and any subset range therebetween without stating each possible subset; and (2) optionally in combination with one or more additives. Each of the skins may be the same or different in composition, and each of the skins may comprises, consist essentially of or consists of any copolymer or terpolymer comprising carbons from C1-C8, optionally in combination with one or more additives, including an antiblock, e.g, ABPP 05 SC (or other PMMA or other antiblock such as silica, silicone, etc.), in at least one of the skin layers. Using PP-PCR 1 or PP-PCR Total rPPH03GR instead of the PP-PIR resulted in no production possible, and only borderline film production occurs with PP-PCR-2.
Example 6 is a transparent standard BOPP film for purpose in packaging or tape application and contains 100% of the PP-PIR (Table 1) in the base layer. In alternate, example embodiments, the core layer may optionally in combination with one or more additives. Each of the skins may be the same or different in composition, and each of the skins may comprise, consist essentially of or consist of any copolymer and/or terpolymer comprising carbons from C1-C8, optionally in combination with one or more additives, including an antiblock, e.g, ABPP 05 SC, in at least one of the skin layers.
Tables 2 and 3 show stable productions and non-stable productions, respectively, as summaries of the references and examples shown above in this disclosure, wherein measurement standards are: film thickness (ASTM D882), area weight (ASTM 8136), density (ASTM D792-98), and haze measurements (ASTM D1003).
With regard to Table 3, BOPP WAL stands for biaxially oriented wrap around label, BOPP PSL stands for biaxially oriented pressure sensitive label, and 25 μm BOPP is a transparent (i.e., clear) biaxially oriented polypropylene film. It is noted that the foregoing films resulted in the same stable and non-stable production summaries when monoaxially oriented instead of being biaxially oriented. It is noted that when filter pressure for SPW-63 is at or below 100 g/m2, more preferably at or below 75 g/m2, and still more preferably 50 g/m2, then use of reclaimed PP results in stable productions for films and labels containing from about 5 wt. % through about 95 wt. % in at least the core layer. And, better
The polypropylene (“PP”) that is preferably used in the core layer is a homopolymer or copolymer comprising from 60 wt. % or 70 wt. % or 80 wt. % or 85 wt. % or 90 wt. % or 95 wt. % or 98 wt. % or 99 wt. % to 100 wt. % propylene-derived units (and comprising within the range of from 0 wt. % or 1 wt. % or 5 wt. % to 10 wt. % or 15 wt. % or 20 wt. % or 30 wt. % or 40 wt. % C2 and/or C4 to C10 α-olefin derived units) and can be made by any desirable process using any desirable catalyst as is known in the art, such as a Ziegler-Natta catalyst, a metallocene catalyst, or other single-site catalyst, using solution, slurry, high pressure, or gas phase processes. Polypropylene copolymers are useful polymers in certain embodiments, especially copolymers of propylene with ethylene and/or butene, and comprise propylene-derived units within the range of from 70 wt. % or 80 wt. % to 95 wt. % or 98 wt. % by weight of the polypropylene. In any case, useful polypropylenes have a melting point (ASTM D3418) of at least 125° C. or 130° C. or 140° C. or 150° C. or 160° C., or within a range of from 125° C. or 130° C. to 140° C. or 150° C. or 160° C. A “highly crystalline” polypropylene is useful in certain embodiments, and is typically isotactic and comprises 100 wt. % propylene-derived units (propylene homopolymer) and has a relatively high melting point of from greater than (greater than or equal to) 140° C. or 145° C. or 150° C. or 155° C. or 160° C. or 165° C.
The term “crystalline,” as used herein, characterizes those polymers which possess high degrees of inter- and intra-molecular order. Preferably, the polypropylene has a heat of fusion (Hf) greater than 60 J/g or 70 J/g or 80 J/g, as determined by DSC analysis. The heat of fusion is dependent on the composition of the polypropylene; the thermal energy for the highest order of polypropylene is estimated at 189 J/g that is, 100% crystallinity is equal to a heat of fusion of 189 J/g. A polypropylene homopolymer will have a higher heat of fusion than a copolymer or blend of homopolymer and copolymer. Also, the polypropylenes useful herein may have a glass transition temperature (ISO 11357-1, Tg) preferably between −20° C. or −10° C. or 0° C. to 10° C. or 20° C. or 40° C. or 50° C. Preferably, the polypropylenes have a Vicat softening temperature (ISO 306, or ASTM D 1525) of greater than 120° C. or 110° C. or 105° C. or 100° C., or within a range of from 100° C. or 105° C. to 110° C. or 120° C. or 140° C. or 150° C., or a particular range of from 110° C. or 120° C. to 150° C.
Preferably, the polypropylene has a melt flow rate (“MFR” or melt flow index “MFI”, 230° C., 2.16 kg, ASTM D1238) within the range of from 0.1 g/10 min or 0.5 g/10 min or 1 g/10 min to 4 g/10 min or 6 g/10 min or 8 g/10 min or 10 g/10 min or 12 g/10 min or 16 g/10 min or 20 g/10 min. Also, the polypropylene may have a molecular weight distribution (determined by GPC) of from 1.5 or 2.0 or 2.5 to 3.0 or 3.5 or 4.0 or 5.0 or 6.0 or 8.0, in certain embodiments. Suitable grades of polypropylene that are useful in the oriented films described herein include those made by ExxonMobil, LyondellBasell, Total, Borealis, Japan Polypropylene, Mitsui, and other sources.
In some embodiments, the skin layer comprises at least one polymer selected from the group comprising, consisting essentially of, and/or consisting of polypropylene copolymers or terpolymers (e.g., EPB shown in the tables), which may be grafted or copolymerized, and a metallocene based material of either polypropylene or ethylene propylene copolymer.
The skin layer may also comprise processing aid additives, such as anti-block agents, anti-static agents, slip agents and combinations thereof, as discussed in further detail below.
The thickness of the skin layer depends upon the intended function of the skin layer, but is typically in the range of from about 0.20 μm through 3.5 μm, or from 0.30 μm through 2 μm, or in many embodiments, from 0.50 μm through 1.0 μm. In thin film embodiments, the skin layer thickness may range from about 0.20 μm through 1.5 μm, or 0.50 μm through 1.0 μm.
Additives present in the film's layer(s) may include, but are not limited to opacifying agents, pigments, colorants, cavitating agents, slip agents, antioxidants, anti-fog agents, anti-static agents, anti-block agents, fillers, moisture barrier additives, gas barrier additives, gas scavengers, and combinations thereof. Such additives may be used in effective amounts, which vary depending upon the property required.
Examples of suitable opacifying agents, pigments or colorants are iron oxide, carbon black, aluminum, titanium dioxide (TiO2), calcium carbonate (CaCO3), and combinations thereof.
Cavitating or void-initiating additives may include any suitable organic or inorganic material that is incompatible with the polymer material(s) of the layer(s) to which it is added, at the temperature of biaxial orientation, in order to create an opaque film. Examples of suitable void-initiating particles are PBT, nylon, solid or hollow pre-formed glass spheres, metal beads or spheres, ceramic spheres, calcium carbonate, talc, chalk, or combinations thereof. The average diameter of the void-initiating particles typically may be from about 0.1 to 10 μm.
Slip agents may include higher aliphatic acid amides, higher aliphatic acid esters, waxes, silicone oils, and metal soaps. Such slip agents may be used in amounts ranging from 0.1 wt % to 2 wt % based on the total weight of the layer to which it is added. An example of a slip additive that may be useful is erucamide.
Non-migratory slip agents, used in one or more skin layers of the multilayered films, may include polymethyl methacrylate (PMMA). The non-migratory slip agent may have a mean particle size in the range of from about 0.5 μm to 8 μm, or 1 μm to 5 μm, or 2 μm to 4 μm, depending upon layer thickness and desired slip properties. Alternatively, the size of the particles in the non-migratory slip agent, such as PMMA, may be greater than 20% of the thickness of the skin layer containing the slip agent, or greater than 40% of the thickness of the skin layer, or greater than 50% of the thickness of the skin layer. The size of the particles of such non-migratory slip agent may also be at least 10% greater than the thickness of the skin layer, or at least 20% greater than the thickness of the skin layer, or at least 40% greater than the thickness of the skin layer. Generally spherical, particulate non-migratory slip agents are contemplated, including PMMA resins, such as EPOSTAR™ (commercially available from Nippon Shokubai Co., Ltd. of Japan). Other commercial sources of suitable materials are also known to exist. Non-migratory means that these particulates do not generally change location throughout the layers of the film in the manner of the migratory slip agents. A conventional polydialkyl siloxane, such as silicone oil or gum additive having a viscosity of 10,000 to 2,000,000 centistokes is also contemplated.
Suitable anti-oxidants may include phenolic anti-oxidants, such as IRGANOX® 1010 (commercially available from Ciba-Geigy Company of Switzerland). Such an anti-oxidant is generally used in amounts ranging from 0.1 wt % to 2 wt %, based on the total weight of the layer(s) to which it is added.
Anti-static agents may include alkali metal sulfonates, polyether-modified polydiorganosiloxanes, polyalkylphenylsiloxanes, and tertiary amines. Such anti-static agents may be used in amounts ranging from about 0.05 wt % to 3 wt %, based upon the total weight of the layer(s).
Examples of suitable anti-blocking agents may include silica-based products such as SYLOBLOC® 44 (commercially available from Grace Davison Products of Colombia, Md.), PMMA particles such as EPOSTAR™ (commercially available from Nippon Shokubai Co., Ltd. of Japan), or polysiloxanes such as TOSPEARL™ (commercially available from GE Bayer Silicones of Wilton, Conn.). Such an anti-blocking agent comprises an effective amount up to about 3000 ppm of the weight of the layer(s) to which it is added.
Useful fillers may include finely divided inorganic solid materials such as silica, fumed silica, diatomaceous earth, calcium carbonate, calcium silicate, aluminum silicate, kaolin, talc, bentonite, clay and pulp.
Optionally, nonionic or anionic wax emulsions can be included in the coating(s), i.e., skin layer(s), to improve blocking resistance and/or lower the coefficient of friction. For example, an emulsion of Michem Lube 215, Michem Lube 160 may be included in the skin layer(s). Any conventional wax, such as, but not limited to Carnauba™ wax (commercially available from Michelman Corporation of Cincinnati, Ohio) that is useful in thermoplastic films is contemplated.
The outer surface (i.e., side facing away from the core) of a skin layer and/or laminating substrate may undergo metallization after optionally being treated. Metallization may be carried out through conventional methods, such as vacuum metallization by deposition of a metal layer such as aluminum, copper, silver, chromium, or mixtures thereof. Following metallization, a coating may be applied to the outer metallized layer “outside” or “inside” the vacuum chamber to result in the following structure: metallized layer/skin layer/optional tie layer/core/optional tie layer/skin layer/metallized layer. In an additional embodiment, a primer may be applied on the metal surface(s) followed by top coating(s).
In certain embodiments, the metal for metallization is metal oxide, any other inorganic materials, or organically modified inorganic materials, which are capable of being vacuum deposited, electroplated or sputtered, such as, for example, SiOx, AlOx, SnOx, ZnOx, IrOx, wherein x=1 or 2, organically modified ceramics “ormocer”, etc. The thickness of the deposited layer(s) is typically in the range from 100 to 5,000 Angstrom or preferably from 300 to 3000 Angstrom.
One or both of the outer surfaces of the multilayered films may be surface-treated to increase the surface energy to render the film receptive to metallization, coatings, printing inks, adhesives, and/or lamination. The surface treatment can be carried out according to one of the methods known in the art including corona discharge, flame, plasma, chemical treatment, or treatment by means of a polarized flame.
An intermediate primer coating may be applied to multilayered films. In this case, the film may be first treated by one of the foregoing methods to provide increased active adhesive sites thereon and to the thus-treated film surface there may be subsequently applied a continuous coating of a primer material. Such primer materials include, for example, epoxy, poly(ethylene imine) (PEI), and polyurethane materials. U.S. Pat. Nos. 3,753,769, 4,058,645 and 4,439,493, each incorporated herein by reference, discloses the use and application of such primers. The primer provides an overall adhesively active surface for thorough and secure bonding with the subsequently applied coating composition and can be applied to the film by conventional solution coating means, for example, by roller application.
The films herein are also characterized in certain embodiments as being biaxially oriented. The films can be made by any suitable technique known in the art, such as a tentered or blown process, LISIM™, and others. Further, the working conditions, temperature settings, lines speeds, etc. will vary depending on the type and the size of the equipment used. Nonetheless, described generally here is one method of making the films described throughout this specification. In a particular embodiment, the films are formed and biaxially oriented using the tentered method. In the tentered process, line speeds of greater than 100 m/min to 400 m/min or more, and outputs of greater than 2000 kg/h to 4000 kg/h or more are achievable. In the tenter process, sheets/films of the various materials are melt-blended and coextruded, such as through a 3, 4, 5, 7-layer die head, into the desired film structure. Extruders ranging in diameters from 100 mm to 300 or 400 mm, and length to diameter ratios ranging from 10/1 to 50/1 can be used to melt blend the molten layer materials, the melt streams then metered to the die having a die gap(s) within the range of from 0.5 or 1 to an upper limit of 3 or 4 or 5 or 6 mm. The extruded film is then cooled using air, water, or both. Typically, a single, large diameter roll partially submerged in a water bath, or two large chill rolls set at 20 or 30 to 40 or 50 or 60 or 70° C. are suitable cooling means. As the film is extruded, an air knife and edge pinning are used to provide intimate contact between the melt and chill roll.
Downstream of the first cooling step in this embodiment of the tentered process, the unoriented film is reheated to a temperature of from 80 to 100 or 120 or 150° C., in one embodiment by any suitable means such as heated S-wrap rolls, and then passed between closely spaced differential speed rolls to achieve machine direction orientation. It is understood by those skilled in the art that this temperature range can vary depending upon the equipment, and in particular, upon the identity and composition of the components making up the film. Ideally, the temperature will be below that which will melt the film, but high enough to facilitate the machine direction orientation process. Such temperatures referred to herein refer to the film temperature itself. The film temperature can be measured by using, for example, infrared spectroscopy, the source aimed at the film as it is being processed; those skilled in the art will understand that for transparent films, measuring the actual film temperature will not be as precise. The heating means for the film line may be set at any appropriate level of heating, depending upon the instrument, to achieve the stated film temperatures.
The lengthened and thinned film is passed to the tenter section of the line for TD orientation. At this point, the edges of the sheet are grasped by mechanical clips on continuous chains and pulled into a long, precisely controlled hot air oven for a pre-heating step. The film temperatures range from 100 or 110 to 150 or 170 or 180° C. in the pre-heating step. Again, the temperature will be below that which will melt the film, but high enough to facilitate the step of transverse direction orientation. Next, the edges of the sheet are grasped by mechanical clips on continuous chains and pulled into a long, precisely controlled hot air oven for transverse stretching. As the tenter chains diverge a desired amount to stretch the film in the transverse direction, the process temperature is lowered by at least 2° C. but typically no more than 20° C. relative to the pre-heat temperature to maintain the film temperature so that it will not melt the film. After stretching to achieve transverse orientation in the film, the film is annealed at a temperature below the melting point, and the film is then cooled from 5 to 10 or 15 or 20 or 30 or 40° C. below the stretching temperature, and the clips are released prior to edge trim, optional coronal, printing and/or other treatment can then take place, followed by winding.
Thus, TD orientation is achieved by the steps of pre-heating the film having been machine oriented, followed by stretching and annealing it at a temperature below the melt point of the film, and then followed by a cooling step at yet a lower temperature. In one embodiment, the films described herein are formed by imparting a transverse orientation by a process of first pre-heating the film, followed by a decrease in the temperature of the process within the range of from 2 or 3 to 5 to 10 or 15 or 20° C. relative to the pre-heating temperature while performing transverse orientation of the film, followed by a lowering of the temperature within the range of from 5° C. to 10 or 15 or 20 or 30 or 40° C. relative to the melt point temperature, holding or slightly decreasing (more than 5%) the amount of stretch, to allow the film to anneal. The latter step imparts the low TD shrink characteristics of the films described herein. Thus, for example, where the pre-heat temperature is 120° C., the stretch temperature may be 114° C., and the cooling step may be 98° C., or any temperature within the ranges disclosed. The steps are carried out for a sufficient time to affect the desired film properties as those skilled in the art will understand.
Thus, in certain embodiments the film(s) described herein are biaxially oriented with at least a 5 or 6 or 7 or 11-fold TD orientation and at least a 2 or 3 or 7-fold MD orientation. Being so formed, the at least three-layer (one core, two skin layers, 18-21 μm thickness) possess an ultimate tensile strength within the range of from 100 or 110 to 80 or 90 or 250 MPa in the TD in certain embodiments; and possess an ultimate tensile strength within the range of from 30 or 40 to 150 or 130 MPa in the MD in other embodiments.
Further example embodiments are provided immediately below.
An oriented film, whether monoaxially or biaxially oriented, may include at least one layer comprising ≥about 5 wt. % through ≤about 95 wt. % of a combination of virgin polypropylene and reclaimed polypropylene, wherein the reclaimed polypropylene has a melt flow index from about 0.5 g/min through about 10 g/min and a dispersion index from about 2 through 10, wherein filter pressure of the reclaimed polypropylene ≤about 50 bar/kg when using a 350-mesh filter on a COLLIN Teach Line Type FT-E20T extruder according to the method and settings above in this description. The at least one layer may be in a two-, three-, four-, five- or more-layered film.
The oriented film in the preceding paragraph may have the at least one layer located in the core layer, in one or more tie layer(s), or any combination thereof. Additionally and alternatively, the oriented film may include one or more additives in any its layer(s) or exclude the presence of any additives in any of its layers. Additives may include calcium carbonate, polybutylene terephthalate, or others as previously described in this disclosure. Furthermore, the core layer and/or its tie layer(s) may include one or more plastomers.
The virgin and reclaimed polypropylenes of the oriented film in the preceding paragraph may be high-crystalline polypropylene, isotactic polypropylene, syndiotactic polypropylene, PP copolymer, or combinations thereof.
The oriented film described in any of the three preceding paragraphs may include at least one skin layer comprising a copolymer and/or terpolymer of ethylene, propylene, and/or butylene polymers.
The oriented film described in any of the four preceding paragraphs may be a label, i.e., also optionally having the addition of any kind of adhesive to a surface of the oriented film and optionally a liner. Additionally and alternatively, the oriented film may have one or more coatings and/or be metallized.
The oriented film described in any of the five preceding paragraphs may be cast, blown, and/or coextruded.
The reclaimed polypropylene in the oriented film described in any of the six preceding paragraphs may include post-industrial reclaimed polypropylene, post-consumer reclaimed polypropylene, or a mixture thereof.
The at least one layer in the oriented film described in any of the seven preceding paragraphs may consist essentially of the reclaimed polypropylene and/or consists of the reclaimed polypropylene. The “and” in this case in when said oriented film may occur in at least two layers of said oriented film.
The oriented film described in any of the eight preceding paragraphs results in a stable production, i.e., the oriented film has no web breaks on a BOPP tenter manufacturing tenter line run from about 50 m/min through about 600 m/min at a temperature from about 80° C. through about 180° C., with a web width anywhere between about 1.5 m through about 10 m over a time period of about 1.5 h.
The at least one layer in the oriented film and/or the oriented film in its entirety described in any of the nine preceding paragraphs may be transparent, translucent, and/or pigmented.
Notably, the shrink of the films and labels described herein have a shrink of ≤about 5% in any direction of orientation, and more preferably ≤about 4% or ≤about 3% if any shrink at all.
The disclosed multilayered films may be stand-alone films, laminates, or webs. Or, the multilayered films may be sealed, coated, metallized, and/or laminated to other film structures. The laminating substrate, itself, may for instance, be a BOPP or a non-oriented, cast or blown PP film or other polymer film with or without the assistance of adhesive(s), increases in temperature and/or pressure, water or solvents, etc.; furthermore, the laminating substrate may or may not be metallized and/or coated. The disclosed multilayered films may be prepared by any suitable methods comprising the steps of co-extruding a multilayered film according to the description and claims of this specification, orienting and preparing the film for intended use such as by coating, printing, slitting, or other converting methods.
For some applications, it may be desirable to laminate the multilayered films to other polymeric film or paper products for purposes such as package decor including printing and metallizing. These activities are typically performed by the ultimate end-users or film converters who process films for supply to the ultimate end-users.
The prepared multilayered film may be used as a flexible packaging film to package an article or good, such as a food item or other product. In some applications, the film may be formed into a pouch type of package, such as may be useful for packaging a beverage, liquid, granular, or dry-powder product.
While the foregoing is directed to example embodiments of the disclosed invention, other and further embodiments may be devised without departing from the basic scope thereof, wherein the scope of the disclosed compositions, systems and methods are determined by one or more claims.
This is a continuation application from and that claims priority to PCT application PCT/IB2024/051430 filed Feb. 15, 2024, which claims priority to U.S. provisional application No. 63/447,363 filed Feb. 22, 2023, U.S. provisional application No. 63/526,210 filed on Jul. 12, 2023, and U.S. provisional application No. 63/548,411 filed on Nov. 14, 2023, all of which are incorporated by this reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 63447363 | Feb 2023 | US | |
| 63526210 | Jul 2023 | US | |
| 63548411 | Nov 2023 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/IB2024/051430 | Feb 2024 | WO |
| Child | 19069397 | US |
