High gloss machine direction oriented polyolefin films

Abstract

Information herein relates to a high gloss machine direction oriented polyolefin film, more particularly, a high gloss machine direction oriented film with high clarity, high transmission, low haze, for use as a labelstock.

Description

HIGH GLOSS MACHINE DIRECTION ORIENTED POLYOLEFIN FILMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Application No. 63 / 680,297, filed August 7, 2024, of which the entire disclosure is incorporated herein by reference.TECHNICAL FIELD

[0002] This disclosure generally relates to a high gloss machine direction oriented polyolefin film. Specifically this disclosure relates to a high gloss machine direction oriented film composition with high clarity, high transmission, low haze, for use as a labelstock.BACKGROUND

[0003] Polypropylene, especially highly isotactic polypropylene, has been used in many applications in the form of molded articles, film, sheets, label stock, etc., because it is generally excellent in molding processability, toughness, moisture resistance, gasoline resistance, and chemical resistance, and it has a low specific gravity, and is relatively inexpensive.

[0004] One specific type of polypropylene, biaxial ly oriented polypropylene (BOPP), has been utilized successfully in down-gauging applications, due to its cost and its exhibition of sufficient stiffness to dispense well. However, all polypropylenes in general disadvantageously exhibit relatively high tensile modulus values in both the machine-direction and cross-direction, which results in labels that are not very conformable. Further, polypropylenes are not easily printable with ultra violet (UV) based inks, which are commonly used to print on pressure sensitive labels, due to the polypropylenes' high surface roughness. Accordingly, it is common practice to improve the printability of polypropylene by adding a print skin (by coextrusion) or a print receptive coating. These solutions, however, add complexity and costs to the production process.

[0005] Additionally, as labels have evolved from conventional colors to higher gloss, a key surface property required for metallic pop is the ability for the metal flakes to lay down flat, and hence reflected light rays are not dispersed in the finished product. This allows for higher gloss surfaces that are smoother for the printed surfaces. In order to provide this surface property, past work has disclosed utilizing high polyethylene content, or high polypropylene content in a blend, which gives high optical properties that are resultant of smoother surfaces, as measured by the root mean square peak to valley height average.However, other properties can suffer as a result by using amounts of high polyethylene, or high polypropylene content in a blended film.SUMMARY

[0006] Exemplary embodiments relate to a composition comprising: a single co-extruded machine direction oriented film layer including 15-75 wt% of at least one of polypropylene homopolymer, polypropylene copolymer, and blends thereof; 15-65 wt% of a polyethylene component; and 5-15 wt% of a propylene-ethylene based copolymer, wherein the propylene-ethylene based copolymer has an ethylene-based content greater than 5% by weight. This embodiment or another embodiment can provide for the polypropylene homopolymer, polypropylene copolymer, and blends thereof comprises between 20-70 wt%. This embodiment or another embodiment can provide for there is a polypropylene copolymer present and the polypropylene copolymer has an ethylene component content of less than 5%. This embodiment or another embodiment can provide for the polyethylene component comprises at least one of: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low density polyethylene (VLDPE), plastomer and elastomer, and combinations thereof. This embodiment or another embodiment can provide for the polyethylene component has a density in the range of 0.90 to 0.915 g cm3. This embodiment or another embodiment can provide for the propylene-ethylene based copolymer is a random block copolymer. This embodiment or another embodiment can provide for the composition has a melt index greater than 1. This embodiment or another embodiment can provide for the composition has a melt index greater than 6. This embodiment or another embodiment can provide for the composition is a calendared film with a first side and a second side opposite the first side. This embodiment or another embodiment can provide for the surface roughness on the first side is less than about 175nm as measured by optical profilometry. This embodiment or another embodiment can provide for the surface roughness on the second side is less than about 215nm as measured by optical profilometry. This embodiment or another embodiment can provide for the first side has a machine direction and a cross direction and has a 60-degree gloss value greater than 40 in the cross direction when measured in accordance with ASTM-D523. This embodiment or another embodiment can provide for the first side has a machine direction and a cross direction and has a 60-degree gloss value greater than 70 in the machine direction when measured in accordance with ASTM-D523. This embodiment or another embodiment can provide for at least one of a heat stabilizer, an ultraviolet radiation absorber, a filler, and a colorant is added. This embodiment or another embodiment can provide for the calendared film has a haze value between about 10 and about 25% when measured in accordance with ASTM D1003. Thisembodiment or another embodiment can provide for the calendared film has a clarity above 60% when measured in accordance with ASTM D1003. This embodiment or another embodiment can provide for the calendared film has a transmission above 90% when measured in accordance with ASTM D1003. This embodiment or another embodiment can provide for the calendared film exhibits a tear strength greater than 8g in a machine direction and 40g in a cross direction measured in accordance with ASTM 1922. This embodiment or another embodiment can provide for the calendared film has a thickness between about 2.0 and about 2.7 mils. This embodiment or another embodiment can provide for a labelstock comprising the calendared film, and an adhesive is applied to the second side and adhered to a substrate and print is applied to a first side.Definitions

[0007] As used herein, the term "label" means a two-dimensional piece of paper, fabric, plastic, or similar material configured to be attached to an object and giving information about it and / or decoration to it. The label may be any suitable shape or design, such as, for example, rectangular, square, circular, oval, triangular, multisided and irregular shapes. The label may have edges and corners that are sharp, rounded, or irregular. Labels may be formed from the laminates described herein with printed indicia thereon.

[0008] As used herein, the term "multilayer" or "laminate" means, a facestock with one or more additional layers. Each layer may have adhesives and / or tie coats in order to adhere the layers together. Alternatively, the layers may be extruded together. Non-limiting examples of such layers to make up the multilayer include protective layers, spacing layers, adhesive layers, optical component-containing layers, metallic layers, barrier layers, release liners, tie coat layers, clear layers, color layers, white layers, reflective layers, fluid transfer layers, strength promoting layers, topcoats, print receptive layers, print containing layers, indicia layers, functional layers, and the like as well as combinations thereof. The resultant multilayer laminate construction described herein can be used for a variety of applications including, but not limited to, graphics applications, such as automobile and architectural wraps; reflective applications, such as road and traffic signs, trains and other commercial vehicles, etc.; and label and packaging applications for battery labels and beyond.

[0009] As used herein, the term "labelstock" means generally material used in part or entirety for creating labels. This labelstock is generally a multilayer or laminate structure.DETAILED DESCRIPTION

[0010] Oriented films can suffer from having poor optical and mechanical properties. Further, as discussed earlier, the higher degree of surface roughness provides some level of difficulty with traditional printing techniques without a print skin or print receptive coating. Accordingly there is a need for high gloss machine direction oriented films having at least one of high clarity, high transmission, low haze film, and a low degree of surface roughness. As such, this disclosure relates to a high gloss machine direction oriented film compositions having at least one of high clarity, high transmission, and low haze without the need for a print skin or print receptive coating. Past work in the area of polymeric films has not well understood the fundamental requirements of a lower haze film. This disclosure expands on the fundamental understanding that through suppressing crystallinity, lower haze will result. Lower haze films allow for additional uses for the film where low haze is desirable, because of aesthetic and / or functional reasons. Blends of polypropylene and polyethylene machine direction oriented films for pressure sensitive labels are disclosed herein. The polypropylene and polyethylene machine direction oriented films can be used in laminates to which can be applied an adhesive on a second side, and a print on a first side. In some embodiments, the laminates are suitable for use as a labelstock.Adhesives

[0011] The labelstocks described herein contain one or more adhesives. The adhesive(s) can be a pressure sensitive adhesive (PSA), a non-pressure sensitive adhesive, a hot-melt adhesive, or combinations thereof. In some embodiments, the adhesive is a PSA. The PSA may be any known PSA. In some embodiments, the PSA is a solvent type adhesive, an emulsion type adhesive, or non-emulsion type adhesive. In some embodiments, the PSA is an emulsion adhesive. Hot melt PSAs may also be used. The adhesive may be acrylic or any other useful adhesive which has the hardness and adhesive properties needed for the laminates and / or adhesive coated facestocks. In certain embodiments, the adhesive can have a hardness sufficient to prevent the adhesive from squeezing out of the laminate or article during processing.

[0012] Exemplary PSAs may be found in (1) Encyclopedia of Polymer Science and Engineering, Vol. 13, Wiley-lnterscience Publishers (New York, 1988); (2) Polymer Science and Technology, Vol. 1, Interscience Publishers (New York, 1964); (3) those described in U.S. Pat. Nos. 5,164,444; 5,183,459; and 5,264,532, all issued to Bernard, and U.S. Pat. No. 5,385,965, issued to Bernard et al; and (4) combinations thereof. In some embodiments, the PSAs may be a solvent based or may be a water based adhesive. Conventional PSAs, including acrylic-based PSAs, rubber-based PSAs and silicone-based PSAs may be usedin the laminates / constructs described herein. In some embodiments, the pressure sensitive adhesive contains an acrylic emulsion adhesive.

[0013] In some embodiments, the pressure sensitive adhesive is prepared by polymerizing alkyl acrylates, vinyl esters, diesters of dicarboxylic acids and unsaturated acids. The alkyl acrylates typically contain from about 2 to about 12, or from about 4 to about 8 carbon atoms in the alkyl group. Examples of alkyl acrylates include, but are not limited to, ethyl, n-butyl, hexyl, 2-ethylhexyl, and isooctyl acrylates, with 2-ethylhexyl acrylate preferred. In some embodiments, the alkyl acrylates are present in an amount of at least about 35%. In some embodiments, the alkyl acrylates are present in an amount from about 35% to about 60% by weight.

[0014] The vinyl esters typically have from about 2 to about 12, or from about 4 to about 8 carbon atoms in the alkyl group. Examples of vinyl esters include, but are not limited to, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl versatate and the like, with vinyl acetate being preferred. In some embodiments, the vinyl esters are present in an amount from about 15% to about 35% or from about 20% to about 25% by weight.

[0015] The diesters of the dicarboxylic acids include alkyl esters of unsaturated diacids, such as maleic acid or anhydride and fumaric acids. The alkyl group generally contains from about 2 to about 20, or from about 4 to about 16, or from about 6 to about 12 carbon atoms. Examples of diesters of diacids include, but are not limited to, butyl, octyl fumarate; hexyl, decyl maleate; di-2-ethylhexyl maleate; dibutyl fumarate; and di-2-ethylhexyl fumarate and mixtures thereof. In some embodiments, the diesters of diacids are present in an amount from about 20% to about 35% by weight.

[0016] The unsaturated acids generally contain from about 2 to about 12, or from about 2 to about 6 carbon atoms. Examples of the unsaturated acids include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, and the like. In some embodiments, the unsaturated acids are present in an amount up to 5% or from about 1% to about 3% by weight.

[0017] In exemplary embodiments, the coat weight of adhesives can be between 1 and 100 gsm.Release Liners

[0018] In some embodiments, the laminates described herein may include one or more release liner(s). In some embodiments, the release liner is disposed on the adhesive. The liner may have a first side, a second side opposed to the first side, a first edge, and a second edge opposed to the second edge. The liner may be any useful liner which provides necessary support and release properties. The liner may be made of, or from, a variety of materials including, but not limited to, paper or polymer film liners. Insome embodiments, the caliper of the paper is sufficient to die cut the resulting laminate or article. For example, liner calipers can range from about 18 pm to 23 pm for PET liners. In some embodiments, the liner has lay flat properties. In some embodiments, the liner has a machine glaze or finish. In some embodiments, the liner has a silicone hold out layer. The hold out layer provides adhesion between the release coating and the release liner. The silicone holdout layer also prevents the silicone release coating from soaking into the liner.

[0019] In some embodiments, the release liner includes a liner having a release coating. The release coating of the release liner provides a releasable bond with the PSA or other adhesive. The release coating may be any composition which provides a desired releasable bond strength.

[0020] In some embodiments, the release coating is a silicone release coating. The release coating can be prepared by curing silicone polymers in the presence of a control release agent. By "control release agent" is meant herein as compounds that can modify the curing time and adhesion properties of adhesives and sealants. In some embodiments, the control release agent is a copolymer of a monofunctional silicone unit of the formula RaSiOi / ? and tetrafunctional silicone units SiC / z wherein R is an alkyl or alkenyl group. In some embodiments, the alkyl or alkenyl groups contain from about 1 to about 12, or from about 1 to about 6 carbon atoms. Non-limiting examples of alkyl and alkenyl groups include methyl, ethyl, propyl, butyl, hexyl, ethenyl, propenyl, butenyl and hexenyl groups.

[0021] The control release agent is typically reacted with a polysiloxane. The polysiloxane may be any polysiloxane which is useful in forming a release coating. Examples of useful polysiloxanes include, but are not limited to, vinyl terminated, hydroxy terminated and epoxy terminated polysiloxanes. In some embodiments, the polysiloxane is a functional polydialkyl siloxane, wherein the alkyl group contains from about 1 to about 6 carbon atoms. The alkyl groups independently include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl groups or mixtures thereof. In some embodiments, the alkyl or alkenyl group contains from 1 to about 12, or from 1 to about 6 carbon atoms. The polysiloxane typically has a viscosity average molecular weight of greater than 300,000 centipoise (cps). In some embodiments, the polysiloxane has a viscosity molecular weight from about 300,000 to about 1,000,000 or more. The polysiloxane may be represented by the formula (I):RO((Si(R)2O)x)— Si)— R (I) wherein each R is independently as defined above and x is an integer.

[0022] In some embodiments, the release coating is prepared with a cross linking agent. In some embodiments, the cross linking agent is a reactive polysiloxane, such as a polydialkyl or polyhydroalkyl siloxane. The alkyl groups can be the same as those described above.

[0023] The release coating may be applied in a solvent, solvent-less or emulsion form. The release coating may be cured by any known curing process, e.g. thermal, radiation, etc., to form the release coating. The curing may be catalyzed by silicone soluble complexed compounds of Group VIII transition metals, such as platinum.

[0024] Commercially available release agents include, but are not limited to, GE SS-4335, a silicone release agent in unreactive solvent. Commercially available polysiloxanes include, but are not limited to, GE SS-4331, a vinyl terminated polydimethyl siloxane. Commercially available linking agents include, but are not limited to, GE SS-4300C, a polymethyvinyl siloxane. Exemplary catalysts include, but are not limited to, SS-8010 catalyst in toluene. These materials are available commercially from General Electric Company's Silicone Products Division. Similar silicone products are available under the tradename Syl-off from Dow Corning Corporation.

[0025] It will be understood that the present subject matter is not limited to any of the noted release coatings or agents, and instead includes nearly any release coating or agent suitable for the intended end use application. Furthermore, although the present subject matter has been described in association with release liners, it will be appreciated that appropriately configured carrier films and other members could be used instead of release liners.Facestock

[0026] In some embodiments, the labelstock includes a facestock. Suitable facestocks include, but are not limited to, synthetic papers such as polyolefin type and polystyrene type; various plastic films or sheets such as polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyurethane, polymethacrylate and polycarbonate. Additional examples of suitable facestocks include paper and cardboard. The facestock may be, or may include, a multilayer polymeric sheet. The multi-layers may be coextruded, or the multi-layers may be laminated together. In some embodiments, the facestock includes both co-extruded multi-layers and laminated multi-layers. In addition, a white opaque film may be formed by adding a white pigment to one or more of the aforementioned synthetic resins and used as the facestock. In some embodiments, a foamed film is used as the facestock. The foamed film may be formed by a conventional foaming operation. In some embodiments, the facestock may be a laminated body formed by combining a plurality of single layered sheets composed of the above listed materials. Examplesof such a laminated body may include the combination of cellulose fiber paper with synthetic paper, and a laminated body of combined cellulose fiber paper with a plastic film or sheet. In some other suitable embodiments, the facestock includes coated and uncoated papers, metalized papers, aluminum foil, laminated paper and paper with a polymeric material extruded onto the surface of the paper. In certain versions, the facestock can be coated with a liquid absorbent material. The selected facestock may be porous or semi-porous. The facestock may exhibit certain visibility characteristics such as opaqueness, color, and / or brightness. The facestock may include water or other liquid absorbency properties. The facestock may be electrically conductive and / or include electrically conductive coatings or regions. A wide array of commercially available facestocks can be used, such as for example those available under the designation TESLIN (available from PPG Industries Ohio, Inc.).

[0027] The thickness of the facestock is optionally determined with reference to application specific criteria. Such criteria may include the desired end use. In some embodiments, the sheet thickness is in a range of from about 10 pm to about 300 pm. In another embodiment, the sheet thickness is in a range of from about 20 pm to about 200 pm. In still another embodiment, the sheet thickness is in a range of from about 30 pm to about 150 pm. Optionally, a primer treatment or a corona discharging treatment or a plasma treatment may be used on the facestock to increase a bonding strength between the facestock and a dried topcoat composition to be formed on a surface of the facestock.

[0028] In certain embodiments described herein, the facestock exhibits one or more functions or functional characteristics. For example, the facestock may be selected to enable or promote an indication such as a visual indication of a liquid, outgassing such as directing or allowing flow of air or gas across a thickness of the facestock, water or liquid retention within the facestock, electrical discharge or conductivity of the facestock, chemical delivery across a thickness of the facestock, passage of sound across a thickness of the facestock, and / or combinations of these functions or characteristics.Optional Layers

[0029] The adhesive coated facestock and / or laminates described herein can include one or more additional layers or components. Non-limiting examples of such layers include protective layers, tie coat layers, clear layers, color layers, white layers, reflective layers, fluid transfer layers, strength promoting layers, topcoats, print receptive layers, print containing layers, indicia layers, functional layers, and the like.Laminate Properties

[0030] The laminates described herein may have specific and useful properties or functionalities.In some embodiments, the techniques described herein enable formation of laminates in which transfer, propagation, and / or migration of liquid, gas, sound waves, electrical current, and / or other agents or elements can occur and is controlled across or through the laminate in a Z-direction. The reference to "Z- direction" as made herein refers to a direction across a thickness dimension of a laminate or portion thereof, and thus references to "X-direction" and / or "Y-direction" refer to directions perpendicular to the Z-direction and correspond to width and length dimensions of the laminate.

[0031] Non-limiting representative examples of laminates having certain functionalities which are provided by the present subject matter include liquid indicator laminates, outgassing laminates, water absorbent laminates, sound channeling laminates, electrically conductive laminates, and laminates having combinations of these functionalities and / or laminates having combinations of one or more of these functionalities and additional functionalities.

[0032] For example, a liquid indicator laminate can be produced such that the speed of the indicator color change is linked to the facestock selection and porous adhesive properties. A discontinuous structure, such as resulting from pores in the adhesive layer or region(s), can allow, for example, liquid to channel through the discontinuous adhesive from one side of the adhesive to the other side and create a permanent discoloration when a dye or other agent in a functional coating in the laminate is dissolved.

[0033] In some embodiments, a liquid indicator laminate is provided. The speed or rate of the indicator color change is linked to the facestock properties, such as for example absorbency of liquid, and porosity of the pattern adhesive in the Z-direction. The indication typically is irreversible and can be measured by color change or by a simple visual comparison.

[0034] The discoloration of a face or region of the laminate can be measured and quantified by optical change, such as by CIE Lab or by a simple visual comparison. The discoloration can be permanent or nonpermanent. The discoloration can also be temporary and revert to an initial state after passage of a period of time. In some embodiments, the period of time is predetermined.

[0035] This phenomenon of transport through discontinuities in an adhesive in the Z-direction can be implemented in other label applications and particularly pressure sensitive adhesive labels, such as for example, labels for outgassing substrates such as by air channeling in the Z-direction, moist substrate labeling such as by liquid channeling in the Z-direction, electrical discharge in the Z-direction, chemical delivery from one layer to another in the Z-direction, and / or sound channeling in the Z-direction. This phenomenon enables passage, transfer, and / or migration of a medium or agent from one side of anadhesive region of a laminate, to another side of the adhesive region. Although medium penetration or transport is noted as being in the Z-direction, it will be understood that the present subject matter is not limited to such and may also include penetration / transport in the X-direction and / or Y-direction.

[0036] In some embodiments, the laminates described herein include a layer or region of a secondary adhesive. The secondary adhesive is typically utilized to adhere the laminate to a substrate of interest. The secondary adhesive may contain one or more adhesives which are the same or different than the adhesive of the patterned or porous adhesive. Description of representative examples of secondary adhesives are provided herein. In such an adhesive configuration, the primary adhesive may be coated onto the facestock, the secondary adhesive may be coated onto the release liner, and the coated adhesive and release liner may be laminated together such that the primary and secondary adhesives are in direct contact with each other. Alternatively, or additionally, both the primary and secondary adhesive may be coated on the facestock or the release liner, then laminated together. It is contemplated that the layering of the primary and secondary adhesive relative to the facestock and the release liner may be either facestock, primary adhesive, secondary adhesive, and release liner or facestock, secondary adhesive, primary adhesive, release liner. Regardless of the order of primary and secondary adhesive, it is contemplated that in some embodiments, at least one of the primary and secondary adhesive is patterned, taking into consideration that the other adhesive may be continuous.

[0037] In some embodiments, an array of different arrangements of layers and components may be utilized. In some embodiments using a patterned adhesive, e.g., the layer of discontinuous adhesive, that layer is disposed between a functional facestock and a liner or functional layer. And in the liquid indicator laminates, the patterned adhesive may be disposed between the functional facestock and the layer or region of functional agent that is sensitive to liquid passing through the laminate. And, in the liquid indicator laminates, the layer or region of the functional agent may be disposed between the patterned adhesive and the carrier layer.

[0038] Utilization of the techniques and features described herein enable production of adhesive laminates and / or adhesive coated facestocks with at least one of fluid / air management characteristics, controlled removability, and / or unique thermal and / or electrical conductivity. In addition, use of these techniques and features enable reductions in materials, e.g., adhesives, and thus enable cost savings. However, it will be understood that the present subject matter includes the adhesive coated facestocks and laminates described herein which are formed by other methods than the methods described herein.Top Coat Formulation and Application

[0039] In exemplary embodiments discussed herein, the top coat coating is deposited on the substrate by any suitable method. In some embodiments, the suitable method includes any suitable coating technology. Embodiments include depositing the coating on the substrate by any suitable liquid deposition method. Without limitation, examples of suitable methods include bath coating, spray coating, slot coating, spin coating, curtain coating, gravure coating, reverse gravure print coating, reverse roll coating, knife over roll (i.e., gap) coating, metering (Meyer) rod coating, air knife coating, or any combinations thereof. Bath coating includes immersion or dip in the aqueous solution. In some embodiments, the coating is deposited by bath in the aqueous solution. In some other embodiments, the coating is deposited by spray of the aqueous solution.Film Construction

[0040] Exemplary embodiments are specifically directed towards a machine direction oriented monolayer film construction intended for use in labelstock. Some of these embodiments may provide for a composition comprising 5-95% by weight of a polypropylene component (homopolymer or random copolymer with ethylene content less than 5% or blends thereof), 95-5% by weight of a polyethylene component (low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low density polyethylene (VLDPE), plastomer and elastomer, and combinations thereof), and 3-20% by weight of a propylene-ethylene based copolymer with ethylene content greater than 5% by weight. Some embodiments may provide for a composition comprising 5-95% by weight of a polypropylene component, 95-5% by weight of a polyethylene component, and 3-20% by weight of a propylene-ethylene based copolymer. Some embodiments may provide for a composition comprising 15-75% by weight of a polypropylene component, 15-65% by weight of a polyethylene component, and 5-15% by weight of a propylene-ethylene based copolymer. In some embodiments, the polypropylene component comprises at least one of polypropylene homopolymer, polypropylene copolymer, and blends thereof. In some embodiments, the polypropylene copolymer has an ethylene content less than 5%. In some embodiments, the polyethylene component comprises at least one of a low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low density polyethylene (VLDPE), plastomer and elastomer, and combinations thereof. In some embodiments, the propylene-ethylene based copolymer has an ethylene content greater than 5% by weight. In some embodiments, the propylene-ethylene based copolymer is a random block copolymer. In some embodiments, the polypropylene homopolymer, polypropylene copolymer, and blends thereof comprises between 20-70 wt%.

[0041] In some embodiments, the polyethylene component has a density in the range of 0.857 to 0.965 g / cm3. In some embodiments, the polyethylene component has a density in the range of 0.90 to 0.915 g / cm3. In some embodiments the polypropylene component is a block copolymer or a random copolymer with C2 content greater than 6% or a block polypropylene (PP) / polyethylene (PE) copolymer.

[0042] Depending on the exact desired implementation, additives such as heat stabilizers, UV absorbers, fillers, and colorants can be added to the film for beneficial properties. For optimum clarity, in some embodiments the polyethylene can have a density of 0.89 to 0.915 g / cm3. In some embodiments, the composition has a melt index of greater than 1. In some embodiments, the compositon has a melt index greater than 5. In some embodiments the composition has a melt index greater than 6. In some embodiments the composition is a calendared film with a first side and a second side opposite the first side. In some embodiments an adhesive is applied to the second side and adhered to a substrate and print is applied to a first side

[0043] In some embodiments the film can be free of halogens and inorganic fillers. Further, in some embodiments the film can be free of any nucleating agent. Even further in some embodiments, the film may be free of hexene, adsorbent silica, any polyacrylic resin, or polylactic derived polymers.Methods

[0044] Having discussed various components of the apparatus, exemplary methods and methodologies of operation will be discussed.

[0045] All examples were produced using a four extruder cast film extrusion process manufactured by Lab Tech with a cast die and an in-line vertical Machine direction orienter was used. Each extruder supplying the polymer melt to a cast die was a 20 mm barrel diameter and a length of 30:1 L / D. The extrusion set up was made to form an ADCBA film structure. Given that the exemplary embodiment was a single layer calendared film, all 4 extruders ran the same composition to obtain a monolayer film. This monolayer film is then suitable for use as label stock.

[0046] Process conditions were identical for each extruder and are summarized below in Tables1-3 with a target film gauge of 2 to 2.5miLTable 1Table 2Table 3

[0047] For all examples, the film samples were trimmed and adhered to glass sides by scotch tape. Broker ContourGT Optical Profiler was utilized to examine and image the sample surface for surface roughness values. Three locations of each sample were randomly chosen for measurements. The examined sample area was 2.3mmx0.6mm. After the raw data was acquired, "Data Restore" and "Gaussian Regression Filter - Short Wavelength Pass" were applied. The regression filter conditions are shown as follows: long cutoff X (mm): 0.05; long cutoff Y (mm): 0.05; short cutoff X (mm): 0; short cutoff Y (mm): 0. Standard surface roughness parameters Sa, Sq and Sz were selected in this case.

[0048] Further, tensile properties were tested in accordance with ASTM D882 using a Sintech(MTS model 1G, 500S). Tear data was done in accordance with ASTM 1922, using a Thwing Albert Protear machine. All haze, clarity, and transmission data was tested in accordance with ASTM D1003 using a HAZE-GARD PLUS 4725. Gloss values were measured in accordance with ASTM-D523 using a Portable BYK Gardner Mirror-TRI-Gloss unit. Caliper was measured using an Emveco Model 210-A Microgauge with drive unit.ExamplesControl Examples 1-5

[0049] Examples 1-5 were produced using the above method and conditions. Component 1 was a polypropylene homopolymer which provides a good balance of desired properties with good melt flow while component 2 was a polyolefin resin that was an ethylene alpha-olefin plastomer. The composition of the samples as well as target gauge are seen within Table 4 below. Resultant properties determined using the methods above are shown in Tables 4-7.Table 4Table 5Table 6Table 7Examples 6-9

[0050] Examples 6-9 were produced using the above method and conditions. Component 3 was an impact polypropylene copolymer (ICP) with 18% ethylene-propylene rubber (EPR). Adding 39% of the ICP, by weight was equivalent to adding 7% EPR. The composition of the samples as well as target gauge are seen within Table 8 below. Resultant properties determined using the methods above are shown in Tables 8-11.Table 8Table 9Table 10Table 11Examples 10-13

[0051] Examples 10-13 were produced using the above method and conditions. The composition of the samples as well as target gauge are seen within Table 12 below. Composition 4 was a propylene / ethylene elastomer with an ethylene content greater than 5% mole. Composition 5 was an antiblock additive. Resultant properties are shown tested with the methods above are shown in TablesTable 12Table 13Table 14Table 15

[0052] Depending on the ultimate use of the film, at least one of a heat stabilizer, an ultraviolet absorber, a filler, and a colorant can be added to the composition at concentrations known in the art for achieving desired properties depending on the desired implementation and use of the film.

[0053] As can be seen from the tables above, all of Examples 10-13 performed very well with respect to transmission (all above 93%), showing results above those of Examples 1-5 or equal to those of Examples 6-9. Further, Examples 10, 11, and 13 all produced the lowest haze values with the exception of Example 1, which was made with 100% PP homopolymer. Example 1 also had high clarity, but Examples 10, 11 and 13 all performed the best when a 100% PP homopolymer is not considered. As discussed above, PP in general disadvantageously exhibit relatively high tensile modulus values in both machine-direction and cross-direction, which results in labels that are not very conformable, and polypropylenes are not easily printable with UV based inks that are most commonly used to print on pressure sensitive labels.

[0054] Thus, pure PP is not desirable. Further, Examples 10-13 all performed better with respect to tear strengths in both the machine direction and the cross direction. The modulus of the materials of all examples 2-13 was also much lower compared to Example 1.

[0055] In some embodiments the surface roughness on the first side is less than about 175nm as measured by optical profilometry. In some embodiments the surface roughness on the second side is less than about 215nm as measured by optical profilometry. In some embodiments the first side has a machine direction and a cross direction and has a 60-degree gloss value greater than 40 in the cross direction when measured in accordance with ASTM-D523. In some embodiments the first side has a machine direction and a cross direction and has a 60-degree gloss value greater than 70 in the machine direction when measured in accordance with ASTM-D523. In some embodiments the calendared film has a haze value between about 10 and about 25% when measured in accordance with ASTM D1003. In some embodiments the calendared film has a clarity above 60% when measured in accordance with ASTM D1003. In some embodiments the calendared film has a transmission above 90% when measured in accordance with ASTM D1003. In some embodiments the calendared film exhibits a tear strength greater than 8g in a machine direction and 40g in a cross direction measured in accordance with ASTM 1922. In some embodiments the calendared film has a thickness between about 2.0 and about 2.7 mils.

[0056] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0057] The articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one." The phrase "and / or," as used herein in the specification and in the claims (if at all), should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and / or" should be construed in the same fashion,i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and / or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B", when used in conjunction with open-ended language such as "comprising" can refer, in some embodiments, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0058] As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and / or B") can refer, in some embodiments, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0059] An embodiment is an implementation or example of the present disclosure. Reference in the specification to "an embodiment," "some embodiments," "one particular embodiment," "another embodiment" or "other embodiments," or the like, means that a particular feature, structure, orcharacteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the invention. The various appearances "an embodiment," "some embodiments," "one particular embodiment," "another embodiment" or "other embodiments," or the like, are not necessarily all referring to the same embodiments.

[0060] If this specification states a component, feature, structure, or characteristic "may","might", or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the element. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0061] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about" or "approximately," even if the term does not expressly appear. The phrase "about" or "approximately" may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / -0. % of the stated value (or range of values), + / -!% of the stated value (or range of values), + / -2% of the stated value (or range of values), + / - % of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0062] Additionally, any method of performing the present disclosure may occur in a sequence different than those described herein. Accordingly, no sequence of the method should be read as a limitation unless explicitly stated. It is recognizable that performing some of the steps of the method in a different order could achieve a similar result.

[0063] In the claims, as well as in the specification above, all transitional phrases such as"comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures.

[0064] In the foregoing description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.

[0065] Moreover, the description and illustration of various embodiments of the disclosure are examples and the disclosure is not limited to the exact details shown or described.

Claims

CLAIMSI claim:

1. A composition comprising: a single co-extruded machine direction oriented film layer including:15-75 wt% of at least one of polypropylene homopolymer, polypropylene copolymer, and blends thereof;15-65 wt% of a polyethylene component; and5-15 wt% of a propylene-ethylene based copolymer, wherein the propylene-ethylene based copolymer has an ethylene-based content greater than 5% by weight.

2. The composition of claim 1, wherein the polypropylene homopolymer, polypropylene copolymer, and blends thereof comprises between 20-70 wt%.

3. The composition of claim 1, wherein there is a polypropylene copolymer present and the polypropylene copolymer has an ethylene component content of less than 5%.

4. The composition of claim 1, wherein the polyethylene component comprises at least one of: linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very low density polyethylene (VLDPE), plastomer and elastomer, and combinations thereof.

5. The composition of claim 1, wherein the polyethylene component has a density in the range of 0.90 to 0.915 g cm3.

6. The composition of claim 1, wherein the propylene-ethylene based copolymer is a random block copolymer.

7. The composition of claim 1, wherein the composition has a melt index greater than 1.

8. The composition of claim 1, wherein the composition has a melt index greater than 6.

9. The composition of claim 1, wherein the composition is a calendared film with a first side and a second side opposite the first side.

10. The calendared film of claim 9, wherein the surface roughness on the first side is less than about 175nm as measured by optical profilometry.

11. The calendared film of claim 9, wherein the surface roughness on the second side is less than about 215nm as measured by optical profilometry.

12. The calendared film of claim 9, wherein the first side has a machine direction and a cross direction and has a 60-degree gloss value greater than 40 in the cross direction when measured in accordance with ASTM-D523.

13. The calendared film of claim 9, wherein the first side has a machine direction and a cross direction and has a 60-degree gloss value greater than 70 in the machine direction when measured in accordance with ASTM-D523.

14. The calendared film of claim 1, further comprising at least one of a heat stabilizer, an ultraviolet radiation absorber, a filler, and a colorant.

15. The calendared film of claim 9, wherein the calendared film has a haze value between about 10 and about 25% when measured in accordance with ASTM D1003.

16. The calendared film of claim 9, wherein the calendared film has a clarity above 60% when measured in accordance with ASTM D1003.

17. The calendared film of claim 9, wherein the calendared film has a transmission above 90% when measured in accordance with ASTM D1003.

18. The calendared film of claim 9, wherein the calendared film exhibits a tear strength greater than 8g in a machine direction and 40g in a cross direction measured in accordance with ASTM 1922.

19. The calendared film of claim 9, wherein the calendared film has a thickness between about 2.0 and about 2.7 mils.

20. A labelstock comprising the calendared film of claim 10 wherein an adhesive is applied to the second side and adhered to a substrate and print is applied to a first side.

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