Patent Application
20200156358
The present disclosure relates to multilayer films containing a slip agent.
Film layers formed from polyolefins are used in multilayer films for confectionary packaging, and specifically for twist packaging for wrapping confectionaries. Multilayer film twist packaging requires a balance of (i) high twist retention to retain the wrapped form, (ii) low coefficient of friction (COF) (e.g., equal to or less than 0.38) to improve machine processing of the multilayer film, and (iii) low yield tension (e.g., less than 16 MPa) to enable permanent deformation of the multilayer film and fold/twist retention with a lower tension applied to the multilayer film. However, polyolefin film layers typically exhibit one or more of poor twist retention, high COF, and high yield tension.
The art recognizes the need for a multilayer film with skin layers containing a polyolefin that exhibits a low COF, high twist retention, and low yield tension.
The present disclosure provides a multilayer film containing at least three layers, including:
Any reference to the Periodic Table of Elements is that as published by CRC Press, Inc., 1990-1991. Reference to a group of elements in this table is by the new notation for numbering groups.
For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent US version is so incorporated by reference) especially with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the art.
The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., 1 or 2, or 3 to 5, or 6, or 7), any subrange between any two explicit values is included (e.g., 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).
Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure.
The term “composition” refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.
The terms “blend” or “polymer blend,” as used herein, is a blend of two or more polymers. Such a blend may or may not be miscible (not phase separated at molecular level). Such a blend may or may not be phase separated. Such a blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art.
The terms “comprising,” “including,” “having” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term “consisting essentially of” excludes from the scope of any succeeding recitation any other component, step, or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any component, step, or procedure not specifically delineated or listed. The term “or,” unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.
An “ethylene-based polymer” is a polymer that contains more than 50 weight percent polymerized ethylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Ethylene-based polymer includes ethylene homopolymer, and ethylene copolymer (having units derived from ethylene and one or more comonomers). The terms “ethylene-based polymer” and “polyethylene” may be used interchangeably. A nonlimiting example of an ethylene-based polymer (polyethylene) is high density polyethylene (HDPE).
An “olefin-based polymer” or “polyolefin” is a polymer that contains more than 50 weight percent polymerized olefin monomer (based on total amount of polymerizable monomers), and optionally, may contain at least one comonomer. Nonlimiting examples of olefin-based polymer include ethylene-based polymer and propylene-based polymer.
A “polymer” is a compound prepared by polymerizing monomers, whether of the same or a different type, that in polymerized form provide the multiple and/or repeating “units” or “mer units” that make up a polymer. The generic term polymer thus embraces the term homopolymer, employed to refer to polymers prepared from only one type of monomer, and the term copolymer, usually employed to refer to polymers prepared from at least two types of monomers. It also embraces all forms of copolymer, e.g., random, block, etc. The terms “ethylene/α-olefin polymer” and “propylene/α-olefin polymer” are indicative of copolymer as described above prepared from polymerizing ethylene or propylene respectively and one or more additional, polymerizable α-olefin monomer. It is noted that although a polymer is often referred to as being “made of” one or more specified monomers, “based on” a specified monomer or monomer type, “containing” a specified monomer content, or the like, in this context the term “monomer” is understood to be referring to the polymerized remnant of the specified monomer and not to the unpolymerized species. In general, polymers herein are referred to has being based on “units” that are the polymerized form of a corresponding monomer.
A “propylene-based polymer” is a polymer that contains more than 50 weight percent polymerized propylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Propylene-based polymer includes propylene homopolymer (having units derived from propylene and no comonomer), and propylene copolymer (having units derived from propylene and one or more comonomers). The terms “propylene-based polymer” and “polypropylene” may be used interchangeably. A nonlimiting example of a propylene-based polymer (polypropylene) is a propylene/α-olefin copolymer with at least one C2 or C4-C10 α-olefin comonomer, or a C2 α-olefin comonomer.
Coefficient of Friction (COF) is measured according to ASTM D1894. The substrate employed for COF determinations is DOW HDPE DGDB-2480 NT, which is a high-density polyethylene commercially available from The Dow Chemical Company, Midland, Mich., USA.
Density is measured in accordance with ASTM D792, Method B. The result is recorded in g/cc.
Melt index (MI) (12) in g/10 min for ethylene-based polymers is measured using ASTM D-1238-04 (190° C./2.16 kg).
Melt flow rate (MFR) in g/10 min for propylene-based polymers is measured using ASTM D-1238-04 (230° C./2.16 kg).
Twist retention after 7 days aging is determined by the following procedure. The film is cut into a 80 mm×80 mm sample. A person then folds the film sample around a piece of Arcor™ Butter Toffee (a hard candy). The person then twists opposing ends of the film tightly around the hard candy piece to resemble the twist-wrapped hard candy single as shown in
Yield tension is measured in accordance with ASTM D882. Yield tension is measured in the machine direction of the film.
Differential Scanning calorimetry (DSC) can be used to measure the melting, crystallization, and glass transition behavior of a polymer over a wide range of temperature. For example, the TA Instruments Q1000 DSC, equipped with an RCS (refrigerated cooling system) and an autosampler is used to perform this analysis. During testing, a nitrogen purge gas flow of 50 ml/min is used. Each sample is melt pressed into a thin film at 190° C.; the melted sample is then air-cooled to room temperature (25° C.). A 3-10 mg, 6 mm diameter specimen is extracted from the cooled polymer, weighed, placed in a light aluminum pan (50 mg), and crimped shut. Analysis is then performed to determine its thermal properties.
The thermal behavior of the sample is determined by ramping the sample temperature up and down to create a heat flow versus temperature profile. First, the sample is rapidly heated to 180° C. and held isothermal for 3 minutes in order to remove its thermal history. Next, the sample is cooled to −80° C. at a 10° C./minute cooling rate and held isothermal at −80° C. for 3 minutes. The sample is then heated to 180° C. (this is the “second heat” ramp) at a 10° C./minute heating rate. The cooling and second heating curves are recorded. The values determined are extrapolated onset of melting, Tm, and extrapolated onset of crystallization, Tc. Heat of fusion (Hf) (in Joules per gram), the calculated % crystallinity for polyethylene samples using the following equation: % Crystallinity=((Hf)/292 J/g)×100; and the calculated % crystallinity for polypropylene samples using the following equation: % Crystallinity=((Hf)/165 J/g)×100.
The heat of fusion (Hf) and the peak melting temperature are reported from the second heat curve. Peak crystallization temperature is determined from the cooling curve.
Melting point, Tm, is determined from the DSC heating curve by first drawing the baseline between the start and end of the melting transition. A tangent line is then drawn to the data on the low temperature side of the melting peak. Where this line intersects the baseline is the extrapolated onset of melting (Tm). This is as described in Bernhard Wunderlich, The Basis of Thermal Analysis, in Thermal Characterization of Polymeric Materials 92, 277-278 (Edith A. Turi ed., 2d ed. 1997).
13C NMR is used for ethylene content and is performed as follows:
Sample Preparation (propylene-based polymers)—The samples are prepared by adding approximately 2.7 g of a 50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene containing 0.025 M Cr(AcAc)3 to 0.20-0.30 g sample in a Norell 1001-7 10 mm NMR tube. The samples are dissolved and homogenized by heating the tube and its contents to 150° C. using a heating block and heat gun. Each sample is visually inspected to ensure homogeneity.
Data Acquisition Parameters (propylene-based polymers)—The data is collected using a Bruker 400 MHz spectrometer equipped with a Bruker Dual DUL high-temperature CryoProbe. The data is acquired using 320 transients per data file, a 6 sec pulse repetition delay, 90 degree flip angles, and inverse gated decoupling with a sample temperature of 120° C. All measurements are made on non-spinning samples in locked mode. Samples are allowed to thermally equilibrate for 7 minutes prior to data acquisition. Percent mm tacticity and wt % ethylene is then determined according to methods commonly used in the art.* *References: For composition (wt % E): S. Di Martino and M. Kelchtermans; J. Appl. Polym. Sci., V 56, 1781-1787 (1995); Tacticity, detailed assignments: V. Busico, R. Cipullo; Prog. Polym. Sci. V 26, 443-533 (2001).
The present disclosure provides a multilayer film. In an embodiment, the multilayer film contains at least three layers, including (A) a core layer containing a high density polyethylene (HDPE) having a density from 0.940 g/cc to 0.980 g/cc; and (B) skin layers on opposite sides of the core layer. Each skin layer includes (i) a propylene homopolymer; (ii) from 2,000 to 3,500 ppm of a slip agent; and (iii) from 4,000 to 10,000 ppm of an antiblock agent.
The multilayer film contains a core layer. The core layer contains a high density polyethylene (HDPE) having a density from 0.940 g/cc to 0.980 g/cc.
“High density polyethylene” (or “HDPE”) is an ethylene homopolymer or an ethylene/α-olefin copolymer with at least one C4-C10 α-olefin comonomer, or C8 α-olefin comonomer and a density from 0.940 g/cc, or 0.945 g/cc, or 0.950 g/cc, or 0.955 g/cc, or 0.958 g/cc to 0.960 g/cc, or 0.962 g/cc, or 0.965 g/cc, or 0.970 g/cc, or 0.975 g/cc, or 0.980 g/cc. In an embodiment, the HDPE has a density from greater than 0.940 g/cc, or 0.945 g/cc, or 0.950 g/cc, or 0.955 g/cc, or 0.958 g/cc to 0.960 g/cc, or 0.962 g/cc, or 0.965 g/cc, or 0.970 g/cc, or 0.975 g/cc, or 0.980 g/cc. The HDPE can be a monomodal copolymer or a multimodal copolymer. A “monomodal ethylene copolymer” is an ethylene/C4-C10 α-olefin copolymer that has one distinct peak in a gel permeation chromatography (GPC) showing the molecular weight distribution. A nonlimiting example of a suitable monomodal HDPE is AXELERON™ FO 6318 BK CPD, available from The Dow Chemical Company. A “multimodal ethylene copolymer” is an ethylene/C4-C10 α-olefin copolymer that has at least two distinct peaks in a GPC showing the molecular weight distribution. Multimodal includes copolymer having two peaks (bimodal) as well as copolymer having more than two peaks. Nonlimiting examples of suitable multimodal HDPE include DOW™ High Density Polyethylene (HDPE) Resins (available from The Dow Chemical Company), ELITE™ Enhanced Polyethylene Resins (available from The Dow Chemical Company), CONTINUUM™ Bimodal Polyethylene Resins (available from The Dow Chemical Company), LUPOLEN™ (available from LyondellBasell), as well as HDPE products from Borealis, Ineos, and ExxonMobil.
In an embodiment, the HDPE includes from greater than 50 wt %, or 55 wt %, or 60 wt %, or 65 wt % to 70 wt %, or 75 wt %, or 80 wt %, or 85 wt %, or 90 wt %, or 95 wt %, or 97 wt %, or 99 wt %, or 100 wt % units derived from ethylene and a reciprocal amount, or from 0 wt %, or 1 wt %, or 3 wt %, or 5 wt %, or 10 wt %, or 15 wt %, or 20 wt %, or 25 wt %, or 30 wt % to 35 wt %, or 40 wt %, or 45 wt %, or less than 50 wt % units derived from a comonomer, based on the total weight of the HDPE.
In an embodiment, the HDPE has a melt index (MI) of from 0.1 g/10 min, or 0.5 g/10 min to 1.0 g/10 min, or 1.5 g/10 min, or 2.0 g/10 min. In another embodiment, the HDPE has a melt index (MI) from 0.1 g/10 min to less than 2.0 g/10 min.
In an embodiment, the HDPE has one, some, or all of the following properties:
In an embodiment, the HDPE has at least 2, or all 3 of properties (i)-(iii).
In an embodiment, the HDPE is an ethylene homopolymer. In another embodiment, the HDPE is an ethylene homopolymer with a density of 0.962 g/cc and a melt index of 0.85 g/10 min. In a further embodiment, the HDPE is ELITE™ 5960G, available from The Dow Chemical Company.
In an embodiment, the core layer contains from 80 wt %, or 85 wt %, or 90 wt %, or 95 wt % to 97 wt %, or 98 wt %, or 99 wt %, or 100 wt % of the HDPE, based on the total weight of the core layer.
In an embodiment, the core layer includes an optional additive. Nonlimiting examples of suitable additives include antioxidants, antistatic agents, stabilizing agents, nucleating agents, colorants, ultra violet (UV) absorbers or stabilizers, flame retardants, compatibilizers, plasticizers, fillers, processing aids, crosslinking agents (e.g., peroxides), and combinations thereof.
In an embodiment, the core layer excludes an antiblocking agent and/or a slip agent.
In an embodiment, the core layer contains from 80 wt %, or 85 wt %, or 90 wt %, or 95 wt % to 97 wt %, or 98 wt %, or 99 wt %, or 100 wt % of the HDPE, and from 0 wt %, or 0.01 wt %, or 0.05 wt %, or 0.1 wt %, or 0.2 wt % to 0.3 wt %, or 0.4 wt %, or 0.5 wt %, or 1.0 wt %, or 2.0 wt %, or 3.0 wt % additive, based on the total weight of the core layer.
In an embodiment, the core layer consists essentially of, or consists of, from 80 wt %, or 85 wt %, or 90 wt %, or 95 wt % to 97 wt %, or 98 wt %, or 99 wt %, or 100 wt % of the HDPE, and from 0 wt %, or 0.01 wt %, or 0.05 wt %, or 0.1 wt %, or 0.2 wt % to 0.3 wt %, or 0.4 wt %, or 0.5 wt %, or 1.0 wt %, or 2.0 wt %, or 3.0 wt % additive, based on the total weight of the core layer.
The HDPE may be the sole polymeric component in the core layer, or the HDPE may be present in a blend with one or more polymeric components in combination with the HDPE. A nonlimiting example of a suitable polymeric component is a polyolefin, such as an ethylene-based polymer or a propylene-based polymer. The optional polyolefin is different than the HDPE. However, it is understood that the core layer may include a blend of two or more different HDPE. In an embodiment, the core layer excludes an optional polyolefin. In another embodiment, the core layer excludes propylene-based polymers.
The core layer has two opposing surfaces. In an embodiment, the core layer is a continuous layer with two opposing surfaces.
In an embodiment, the core layer has a thickness of from 6.0 μm, or 7.0 μm, or 8.0 μm, or 9.0 μm, or 10.0 μm, or 11.0 μm, or 12.0 μm, or 13.0 μm, or 14.0 μm, or 15.0 μm, or 16.0 μm, or 17.0 μm, or 18.0 μm, or 19.0 μm, or 19.8 μm to 22.2 μm, or 23.0 μm, or 25 μm, or 30 μm, or 35 μm, or 40 μm, or 45 μm, or 50 μm, or 65 μm, or 70 μm, or 75 μm, or 80 μm, or 85 μm, or 90 μm.
The core layer may comprise two or more embodiments disclosed herein.
The multilayer film contains skin layers on opposite sides of the core layer. Each skin layer includes (i) a propylene homopolymer; (ii) from 2,000 to 3,500 ppm of a slip agent; (iii) from 4,000 to 10,000 ppm of an antiblock agent; and, optionally, (iv) an additive.
In an embodiment, each skin layer consists essentially of, or consists of, (i) a propylene homopolymer; (ii) from 2,000 to 3,500 ppm of a slip agent; (iii) from 4,000 to 10,000 ppm of an antiblock agent; and, optionally, (iv) an additive.
In an embodiment, each skin layer has a thickness of from 0.75 μm, or 1.0 μm, or 1.5 μm, or 2.0 μm, or 3.0 μm, or 4.0 μm, or 5.0 μm, or 6.0 μm, or 6.5 μm to 7.0 μm, or 7.5 μm, or 8.0 μm, or 9.0 μm, or 10.0 μm, or 11.0 μm, or 12.0 μm, or 13.0 μm, or 14.0 μm, or 15.0 μm, or 20.0 μm, or 25.0 μm, or 30 μm. Each skin layer may have the same thickness or a different thickness.
The skin layers may comprise two or more embodiments disclosed herein.
i. Propylene Homopolymer
Each skin layer contains a propylene homopolymer. The propylene homopolymer contains 100 wt % units derived from propylene.
The propylene homopolymer is void of comonomer (e.g., ethylene). In an embodiment, the propylene homopolymer consists of propylene and an optional additive.
A nonlimiting example of a suitable propylene homopolymer is CUYOLEN™ 1102L, available from Petroquimica Cuyo S.A.I.C.
In an embodiment, the propylene homopolymer has a melt flow rate (MFR) from 2.0 g/10 min, or 3.0 g/10 min, or 4.0 g/10 min to 5.0 g/10 min, or 6.0 g/10 min, or 7.0 g/10 min, or 8.0 g/10 min, or 9.0 g/10 min, or 10.0 g/10 min, or 15.0 g/10 min, or 20.0 g/10 min, or 25.0 g/10 min. In an embodiment, the propylene homopolymer has a melt flow rate (MFR) from greater than 2.0 g/10 min to 25 g/10 min, or from greater than 2.0 g/10 min to 15.0 g/10 min, or from 2.5 g/10 min to 6.0 g/10 min.
In an embodiment, the propylene homopolymer has a density from 0.900 g/cc, or 0.902 g/cc, 0.903 g/cc, or 0.904 g/cc to 0.906 g/cc, or 0.908 g/cc.
In an embodiment, the propylene homopolymer has a melting temperature, Tm, from 155° C., or 157° C., or 159° C. to 161° C., or 163° C., or 165° C.
In an embodiment, the propylene homopolymer has one, some, or all of the following properties:
In an embodiment, the propylene homopolymer has at least 2, or all of properties (i)-(iii).
In an embodiment, the propylene homopolymer has a melt flow rate (MFR) of 5.0 g/10 min, a density of 0.903 g/cc, and/or a melting point of 161° C. In a further embodiment, the propylene homopolymer is CUYOLEN™ 1102L, available from Petroquimica Cuyo S.A.I.C.
In an embodiment, each skin layer contains from 70 wt %, or 75 wt %, or 77 wt % to 80 wt %, or 83 wt %, or 85 wt %, or 90 wt %, or 95 wt %, or 96 wt %, or 97 wt %, or 98 wt %, or 99 wt %, or 99.3 wt %, or 99.4 wt %, or less than 100 wt % propylene homopolymer, based on the total weight of each skin layer.
The propylene homopolymer may comprise two or more embodiments disclosed herein.
ii. Slip Agent
Each skin layer contains a slip agent. A “slip agent” is a compound that has a coefficient of friction (COF) from 0.02 to 0.15. In an embodiment, the slip agent has a COF of from 0.02, or 0.04, or 0.06, or 0.07, or 0.08, or 0.09, or 0.10 to 0.15.
Nonlimiting examples of suitable slip agents include fatty acid amides, silicone, plasticizers, organic amines, dibasic esters, stearates, sulfates, fatty acids, mineral oil, vegetable oils, fluorinated organic resins, graphite, tungsten disulfide, molybdenum disulfide, and combinations thereof.
In an embodiment, the slip agent is a fatty acid amide. A “fatty acid amide” is a molecule having the Structure (I):
wherein R is a C3 to C27 alkyl moiety. In an embodiment, R is a C11 to C25, or a C15 to C23 alkyl moiety. In another embodiment, R is a C21 alkyl moiety. R can be saturated, mono-unsaturated, or poly-unsaturated. In an embodiment, R is mono-unsaturated. Nonlimiting examples of suitable fatty acid amides include erucamide, oleamide, palmitamide, stearamide, and behenamide. Additionally, the fatty acid amide can be a mixture of two or more fatty acid amides. In an embodiment, the fatty acid amide is erucamide.
In an embodiment, the slip agent is a silicone. A “silicone” is a polymer generally comprising siloxane-based monomer residue repeating units. A “siloxane” is a monomer residue repeat unit having the Structure (II):
wherein R1 and R2 each independently is hydrogen or a hydrocarbyl group. A “hydrocarbyl group” is a univalent group formed by removing a hydrogen atom from a hydrocarbon (e.g., alkyl groups, such as ethyl, or aryl groups, such as phenyl). The siloxane monomer residue can be any dialkyl, diaryl, dialkaryl, or diaralkyl siloxane, having the same or differing alkyl, aryl, alkaryl, or aralkyl moieties. In an embodiment, each of R1 and R2 is independently a C1 to C20, or C1 to C12, or C1 to C6 alkyl, aryl, alkaryl, or aralkyl moiety. R1 and R2 can have the same or a different number of carbon atoms. In an embodiment, the hydrocarbyl group for each of R1 and R2 is an alkyl group that is saturated and optionally straight-chain. The alkyl group can be the same or can be different for each of R1 and R2. Non-limiting examples of alkyl groups suitable for use in R1 and R2 include methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, isobutyl, t-butyl, or combinations of two or more thereof. Nonlimiting examples of suitable silicone include polydimethylsiloxane (PDMS), poly(ethyl-methylsiloxane), and combinations thereof.
In an embodiment, the slip agent is selected from a fatty acid amide, a silicone, and combinations thereof. In another embodiment, the slip agent is selected from erucamide, oleamide, palmitamide, stearamide, behenamide, PDMS, and combinations thereof.
In an embodiment, the slip agent excludes silicones. In a further embodiment, the slip agent excludes polydimethylsiloxane (PDMS).
In an embodiment, the slip agent is a stearate. Nonlimiting examples of suitable stearates include zinc stearate, lead stearate, calcium stearate, and combinations thereof.
In an embodiment, the slip agent is a sulfate. A nonlimiting example of a suitable sulfate is zinc sulfate.
In an embodiment, the slip agent is a fatty acid. Nonlimiting examples of suitable fatty acids include palmitic acid, stearic acid, and combinations thereof.
In an embodiment, the slip agent is a fluorinated organic resin. A “fluorinated organic resin” is a polymer of one or more fluorinated monomers selected from tetrafloroethylene, vinylidene fluoride, and chlorotrifluoroethylene.
In an embodiment, each skin layer contains from 2,000 ppm, or 2,500 ppm, or 3,000 ppm, or 3,100 ppm, or 3,200 ppm to 3,300 ppm, or 3,400 ppm, or 3,500 ppm slip agent.
In an embodiment, each skin layer contains from 0.20 wt %, or 0.25 wt %, or 0.30 wt %, or 0.31 wt %, or 0.32 wt % to 0.33 wt %, or 0.34 wt %, or 0.35 wt % slip agent, based on the total weight of each skin layer.
The slip agent may comprise two or more embodiments disclosed herein.
iii. Antiblock Agent
Each skin layer contains an antiblock agent. An “antiblock agent” is a compound that minimizes, or prevents, blocking (i.e., adhesion) between two adjacent layers of film by creating a microscopic roughening of the film layer surface, which reduces the available contact area between adjacent layers.
Nonlimiting examples of suitable antiblock agents include silica, talc, calcium carbonate, and combinations thereof. In an embodiment, the antiblock agent is silica (SiO2). The silica may be organic silica or synthetic silica.
In an embodiment, each skin layer contains from 4,000 ppm, or 4,500 ppm, or 5,000 ppm, or 5,500 ppm, or 6,000 ppm to 6,500 ppm, or 7,000 ppm, or 7,500 ppm, or 8,000 ppm, or 8,500 ppm, or 9,000 ppm, or 9,500 ppm, or 10,000 ppm antiblock agent.
In an embodiment, each skin layer contains from 0.40 wt %, or 0.45 wt %, or 0.50 wt %, or 0.55 wt %, or 0.60 wt % to 0.65 wt %, or 0.70 wt %, or 0.75 wt %, or 0.80 wt %, or 0.85 wt %, or 0.90 wt %, or 0.95 wt %, or 1.00 wt % antiblock agent, based on the total weight of each respective skin layer.
The antiblock agent may comprise two or more embodiments disclosed herein.
iv. Optional Additives
In an embodiment, each skin layer includes an optional additive. The optional additive may be any additive disclosed herein. In an embodiment, each skin layer contains an additive selected from antioxidants, antistatic agents, stabilizing agents, nucleating agents, colorants, ultra violet (UV) absorbers or stabilizers, flame retardants, compatibilizers, plasticizers, fillers, processing aids, crosslinking agents (e.g., peroxides), and combinations thereof.
In an embodiment, each skin layer contains from 0 wt %, or 0.01 wt %, or 0.05 wt %, or 0.1 wt %, or 0.2 wt % to 0.3 wt %, or 0.4 wt %, or 0.5 wt %, or 1.0 wt %, or 2.0 wt %, or 3.0 wt % additive, based on the total weight of each skin layer.
The propylene homopolymer may be the sole polymeric component in each skin layer, or the propylene homopolymer may be present in a blend with one or more polymeric components in combination with the propylene homopolymer. A nonlimiting example of a suitable polymeric component is a polyolefin, such as an ethylene-based polymer or a propylene-based polymer. The optional polyolefin is different than the propylene homopolymer. However, it is understood that each skin layer may include a blend of two or more different propylene homopolymers. In an embodiment, each skin layer excludes an optional polyolefin. In another embodiment, each skin layer excludes ethylene-based polymers. In an embodiment, each skin layer includes from 15 wt %, or 16 wt % to 18 wt %, or 20 wt %, or 22 wt %, or 25 wt %, or 30 wt % ethylene-based polymer, based on the total weight of each skin layer.
In an embodiment, each skin layer contains:
In an embodiment, each skin layer contains:
It is understood that the sum of the components in each of the skin layers disclosed herein, including the foregoing layers, yields 100 weight percent (wt %), based on the total weight of the respective skin layer.
Each skin layer may have the same or a different composition. In an embodiment, each skin layer has the same composition.
Each skin layer has two opposing surfaces. In an embodiment, each skin layer is a continuous layer with two opposing surfaces.
The skin layers may comprise two or more embodiments disclosed herein.
The multilayer film contains at least three layers including (A) a core layer containing a high density polyethylene (HDPE) having a density from 0.940 g/cc to 0.980 g/cc and, optionally, an additive; and (B) skin layers on opposite sides of the core layer. Each skin layer includes (i) a propylene homopolymer; (ii) from 2,000 to 3,500 ppm of a slip agent; (iii) from 4,000 to 10,000 ppm of an antiblock agent; and, optionally, (iv) an additive. The core layer and the skin layers may be any core layer and skin layer disclosed herein.
The multilayer film contains three layers, or more than three layers. For example, the multilayer film can have three, four, five, six, seven, eight, nine, ten, eleven, or more layers. In an embodiment, the multilayer film contains only three layers.
In an embodiment, the multilayer film consists essentially of, or consists of, at least three layers including (A) the core layer containing HDPE having a density from 0.940 g/cc to 0.980 g/cc and, optionally, an additive; and (B) skin layers on opposite sides of the core layer. Each skin layer includes (i) the propylene homopolymer; (ii) from 2,000 to 3,500 ppm of the slip agent; (iii) from 4,000 to 10,000 ppm of the antiblock agent; and, optionally, (iv) an additive.
The skin layers may be in direct contact or in indirect contact with the core layer. In an embodiment, the skin layers directly contact the core layer. The term “directly contacts,” as used herein, is a layer configuration whereby the core layer is located immediately adjacent to each skin layer and no intervening layers, or no intervening structures, are present between the core layer and each skin layer. In another embodiment, the skin layers indirectly contact the core layer. The term “indirectly contacts,” as used herein, is a layer configuration whereby an intervening layer, or an intervening structure, is present between the core layer and each skin layer.
In an embodiment, the multilayer film has a thickness of from 15 μm, or 20 μm, or 25 μm, or 30 μm, or 33 μm to 37 μm, or 40 μm, or 45 μm, or 50 μm, or 55 μm, or 60 μm, or 65 μm, or 70 μm, or 75 μm, or 80 μm, or 85 μm, or 90 μm, or 95 μm, or 100 μm.
In an embodiment, the core layer is from 40 vol %, or 45 vol %, or 50 vol %, or 55 vol % to 60 vol %, or 65 vol %, or 70 vol %, or 75 vol % or 80 vol %, or 85 vol %, or 90 vol % of the total volume of the multilayer film.
In an embodiment, the combined volume of the skin layers is from 10 vol %, or 15 vol %, or 20 vol %, or 25 vol %, or 30 vol %, or 35 vol %, or 40 vol % to 45 vol %, or 50 vol %, or 55 vol %, or 60 vol % of the total volume of the multilayer film. In an embodiment, the volume of each individual skin layer is from 5 vol %, or 7.5 vol %, or 10 vol %, or 12.5 vol %, or 15 vol %, or 20 vol % to 22.5 vol %, or 25 vol %, or 27.5 vol %, or 30 vol % of the total volume of the multilayer film.
In an embodiment, the core layer has a thickness of from 6.0 μm, or 7.0 μm, or 8.0 μm, or 9.0 μm, or 10.0 μm, or 11.0 μm, or 12.0 μm, or 13.0 μm, or 14.0 μm, or 15.0 μm, or 16.0 μm, or 17.0 μm, or 18.0 μm, or 19.0 μm, or 19.8 μm to 22.2 μm, or 23.0 μm, or 25 μm, or 30 μm, or 35 μm, or 40 μm, or 45 μm, or 50 μm, or 65 μm, or 70 μm, or 75 μm, or 80 μm, or 85 μm, or 90 μm; and each skin layer has a thickness of from 0.75 μm, or 1.0 μm, or 1.5 μm, or 2.0 μm, or 3.0 μm, or 4.0 μm, or 5.0 μm, or 6.0 μm, or 6.5 μm to 7.0 μm, or 7.5 μm, or 8.0 μm, or 9.0 μm, or 10.0 μm, or 11.0 μm, or 12.0 μm, or 13.0 μm, or 14.0 μm, or 15.0 μm, or 20.0 μm, or 25.0 μm, or 30 μm.
In an embodiment, the multilayer film has a slip factor of from 25,000, or 26,000, or 30,000, or 35,000, or 39,000 to 40,000, or 45,000, or 49,000, or 50,000, or 52,000, or 55,000, or 60,000. The “slip factor” of the multilayer film is calculated in accordance with the following Equation (I):
In Equation (I), the weight percent (“wt %”) of each respective layer is based on the total weight of the film.
In an embodiment, the multilayer film has a coefficient of friction (COF) from 0.05, or 0.10, or 0.15, or 0.19, or 0.20, or 0.24 to 0.25, or 0.26, or 0.27, or 0.28, or 0.29, or 0.30, or 0.31, or 0.32, or 0.33, or 0.34, or 0.35, or 0.36, or 0.37, or 0.38.
In an embodiment, the multilayer film has a twist retention after aging 7 days of from 66%, or 70% to 75%, or 80%, or 85%, or 90%, or 95%, or 100%. A higher twist retention after aging 7 days (≥66%) indicates the multilayer film maintains a folded/twisted formation after aging. Consequently, the present multilayer film is suitable for twist packaging.
In an embodiment, the multilayer film has a yield tension from 5 MPa, or 8 MPa, or 10 MPa, or 13 MPa to 14 MPa, or 15 MPa, or 15.5 MPa, or less than 16 MPa. During folding and/or twisting of the multilayer film, tension is applied to the multilayer film and the film elongates and recovers to its original dimensions when the tension is removed, until the tension that is applied is the “yield tension,” at which point the multilayer film elongates but deformation is permanent (indicating the multilayer film maintains its folded/twisted formation). A low yield tension of from 5 MPa to 15.5 MPa, or less than 16 MPa is advantageous because it enables permanent deformation of the multilayer film and fold/twist retention with a lower tension applied to the multilayer film.
In an embodiment, the multilayer film has at least three layers including:
(A) a core layer containing from 80 wt %, or 85 wt %, or 90 wt %, or 95 wt % to 97 wt %, or 98 wt %, or 99 wt %, or 100 wt % HDPE, and from 0 wt %, or 0.01 wt %, or 0.05 wt %, or 0.1 wt %, or 0.2 wt % to 0.3 wt %, or 0.4 wt %, or 0.5 wt %, or 1.0 wt %, or 2.0 wt %, or 3.0 wt % additive, based on the total weight of the core layer, the HDPE having one, some, or all of the following properties:
In an embodiment, the multilayer film has at least 2, or at least 3, or at least 4, or at least 5, or at least 6, or at least 7, or at least 8, or all 9 of properties (1)-(9).
It is understood that the sum of the components in each of the layers disclosed herein, including the foregoing layers, yields 100 weight percent (wt %), based on the total weight of the respective layer.
In an embodiment, the multilayer film is a coextruded film produced via a cast process. The multilayer film produced via a cast process excludes multilayer films produced via a blown process. Not wishing to be bound by any particular theory, Applicants believe the cast process results in a multilayer film with higher stiffness, which results in improved (i.e., higher) twist retention.
In an embodiment, the multilayer film is not an oriented film. In a further embodiment, the multilayer film is not biaxially oriented. In other words, the multilayer film is not stretched after extrusion.
In an embodiment, the multilayer film is coextruded and is not laminated.
The multilayer film may comprise two or more embodiments disclosed herein.
The present disclosure also provides an article containing a multilayer film. The multilayer film may be any multilayer film disclosed herein.
In an embodiment, the article includes a confectionary and a multilayer film in contact with the confectionary. In an embodiment, the multilayer film contains at least three layers including (A) a core layer containing a high density polyethylene (HDPE) having a density from 0.940 g/cc to 0.980 g/cc and, optionally, an additive; and (B) skin layers on opposite sides of the core layer. Each skin layer includes (i) a propylene homopolymer; (ii) from 2,000 to 3,500 ppm of a slip agent; (iii) from 4,000 to 10,000 ppm of an antiblock agent; and, optionally, (iv) an additive.
The article includes a confectionary. Nonlimiting examples of suitable confectionaries include sugar confections, chocolate confections, and combinations thereof. Nonlimiting examples of sugar confections include lollipops, hard candies, soft candies, licorice, caramels, gum, candied nuts, candied fruits, fudge, taffy, marzipan, taffy, brittle, marshmallows, mints, and combinations thereof. Nonlimiting examples of chocolate confections include fudge, chocolate pieces, chocolate bars, chocolate-covered nuts, chocolate-covered fruits, chocolate mints, and truffles.
The multilayer film may be in direct or in indirect contact with the confectionary. In an embodiment, the multilayer film is in direct contact with the confectionary.
The multilayer film may be twisted and/or folded around the confectionary. In an embodiment, the multilayer film is folded and subsequently twisted at opposing ends of the confectionary.
The article may comprise two or more embodiments disclosed herein.
By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following Examples.
Materials used in the examples are provided in Table 1A below.
Multilayer film samples are fabricated on a Collins cast line with the conditions provided in
Table 1B.
The layer configurations and the multilayer film structures are provided below in Table 2. Each multilayer film structure is formed with a core layer (A) having a volume that is 60 volume % of the multilayer film, and two skin layers (B1 and B2). Each skin layer (B1 and B2) has a volume that is 20 volume % of the multilayer film. In other words, the combined skin layers (B1 and B2) make up 40 volume % of the multilayer film. In Table 2, the amount of slip agent and antiblock agent refers to the amount of respective slip agent and antiblock agent contained in the layer (rather than the amount of slip agent masterbatch and/or antiblock agent masterbatch contained in the layer). In Table 2, the contents of each layer are recited in weight percent (wt %) and/or ppm (parts per million), based on the total weight of the respective layer. For example, the skin layer (B1) of Ex 3 contains 78.5 wt % CUYOLEN™ 1102L; 3,500 ppm slip agent (i.e., 0.35 wt % slip agent); 8,000 ppm antiblock agent (i.e., 0.8 wt % antiblock agent); and 20.35 wt % masterbatch polyethylene carrier (“MB PE”) (i.e., the combined amount of (i) 17.15 wt % polyethylene carrier from the slip agent masterbatch and (ii) 3.2 wt % polyethylene carrier from the antiblock agent masterbatch), based on the total weight of the skin layer (B1).
The multilayer film samples are tested for COF, twist retention, and yield tension. The results are provided below in Table 2.
+Coefficient of Friction (COF) was not measured for CS 2 because it exhibited poor twist retention (i.e., ≤50% twist retention), indicating the multilayer film is not suitable for twist packaging.
Comparative sample films containing three layers including (A) a core layer containing HDPE having a density of 0.940-0.980 g/cc; and (B) skin layers on opposite sides of the core layer, the skin layers containing (i) a propylene/ethylene copolymer and no propylene homopolymer; (ii) no slip agent; and (iii) no antiblock agent (CS 3-5) exhibit high COF (>0.38), indicating the multilayer films are not suitable for twist packaging because machine processing of the multilayer film is inhibited when the multilayer film has a COF greater than 0.38.
Applicant surprisingly discovered multilayer films containing three layers including (A) a core layer containing HDPE having a density of 0.940-0.980 g/cc; and (B) skin layers on opposite sides of the core layer, each skin layer containing (i) a propylene homopolymer; (ii) 2,000-3,500 ppm of a slip agent; and (iii) 4,000-10,000 ppm of an antiblock agent (Ex 1, Ex 2, Ex 3) advantageously exhibit a unique balance of high twist retention (66%-100%) to retain the wrapped form, low COF (0.05-0.38) to improve machine processing of the multilayer film, and low yield tension (≤15.5 MPa) to enable permanent deformation of the multilayer film and fold/twist retention with a lower tension applied to the multilayer film, indicating the multilayer films are suitable for twist packaging.
It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/026704 | 4/9/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62484527 | Apr 2017 | US | |
| 62517305 | Jun 2017 | US | |
| 62564633 | Sep 2017 | US |
