MXPA00000016A - Fog-resistant packaging film - Google Patents

Abstract

A packaging film includes a heat sealable layer coated with one or more antifogging agents disposed in a binder, an antiblocking agent, and no more than about 800 ppm slip agent. The heat sealable layer includes a polymer that includes mer units derived from ethylene while the binder includes a polymer that includes mer units derived from an ester of (meth)acrylic acid and/or vinyl acetate monomers. The antiblocking agent can be in any layer of the film where it provides the desired effect. Such a film, as well as packages made therefrom, can be used to package a variety of products, having particular uility with respect to moist products.

Description

PACKING FILM RESISTANT TO THE CLOUD BACKGROUND OF THE INVENTION 1. Field of the invention The film described herein is useful for packaging various products, particularly perishable food products such as, for example, whole and cut agricultural products, and shows excellent resistance to clouding. 2. BACKGROUND OF THE INVENTION Each year, thermoplastic packaging materials are used to enclose and protect an increasing number of products. Many of these products have properties that require packaging materials with special properties. Accordingly, several packaging materials are developed and introduced each year. Due to their flexibility, strength, light weight, etc., thermoplastic films and packaging made from them continue to account for an increasing percentage of the packaging market. However, due to the varied nature of packaged products, films with novel and improved properties are continually required. Products that contain moisture have presented a problem for a long time. Once a product of this type has been packed, evaporation of the product water tends to condense on the internal surface of the package. This is especially true in the case of a packaged product stored at temperatures below ambient temperature as is the case, for example, of agricultural product. As can be expected, manufacturers and retailers insist on presenting the products in an aesthetically pleasing manner and providing the customer with a clear view of the product. However, condensation reduces the potential customers' ability to see the product. Thus, the need for films and packaging that resist this condensation (sometimes called "cloudy") has been developed. In recent years, several solutions have been proposed. However, many of these solutions raised other problems. Surfactants and wetting agents (commonly known as antifouling agents) commonly used to reduce the amount of condensation shown on thermoplastic films and gaskets tend to interfere with the ink's ability to stick to the polymer (s) the movie or packaging. Since a significant portion of the packaging is printed to indicate the source, content, etc., particularly those designed for retail sale, good adhesion of the ink is a prerequisite. Even though antifouling agents are usually applied to the surface of the film or packaging closest to the food product, they tend to migrate to the inside of the film or packaging. When this migration continues to the outer surface of the film or package, the anti-clouding agent (which normally has a low surface tension) may interfere with the adhesion between the ink and the film. This decreased adhesion can result in an increased difficulty in printing the film and / or staining the printed ink on other items or clients. What exacerbates this problem of ink adhesion on the film, additives known as slip agents are frequently used in film making processes. Slip agents are internal lubricants that exit to the surface of the film during its manufacture and immediately afterwards in such a way that they offer a thin coating that reduces the coefficient of friction (COF) that the film would have if said agents were not used. In addition to these slip agents used in the manufacture of polymeric raw materials, film products often add even more slip agents (such as, for example, fatty amides) during the manufacture of the film itself. Even when a film with a lower coefficient of friction can be processed more easily, the same film is more difficult to print andWhen it is printed it has a lesser adhesion between the ink and the film than a similar film that does not contain any slip agent. Thus, there remains a need for a film that (1) has good adhesion to the ink (2) a coefficient of friction low enough to be easily manufactured and processed, and (3) an adequate resistance to clouding. The supply of a film of this type is highly desirable. SUMMARY OF THE INVENTION In summary, the present invention provides a packaging film that includes a thermally sealable layer having a coating with one or more antifouling agents placed in a binder, an antiblocking agent, and no more than about 800 parts per million. (ppm) of slip agent. The thermally sealable layer includes a polymer that includes mer units derived from ethylene while the binder includes a polymer that includes mer units derived from a (meth) methacrylic acid ester and / or vinyl acetate monomer. The antiblocking agent can be found in any of the layers of the film where it offers the desired effect. The film preferably includes a slip agent in an amount no greater than, in ascending order preferably, about 750 ppm, about 700 ppm, about 650 ppm, about 600 ppm, and about 550 ppm. In certain situations, the amount of slip agent present may be from about 500 ppm, about 400 ppm, about 300 ppm, about 200 ppm, about 100 ppm, about 50 ppm, to about 25 ppm. In one embodiment, the film of the present invention can be essentially free of slip agent. The film of the present invention can be a single-layer film, that is, the thermally sealable layer is the only layer. Alternatively, the film of the present invention may be a multilayer film, for certain end-use applications, a film with more than one layer may be preferred. Layers that include a polymer with mer units derived from propylene and / or styrene can offer films with performance characteristics that differ from the performance characteristics of a single layer film. In other aspects, the present invention offers a package made from the film described above as well as a method for using the film described above which includes the introduction of a product into a bag made from the film and then the seal of the film. bag in order to form a package. Films such as those just described have a desirable coefficient of friction and resist cloud formation, even when used to pack wet products. Since the film of the present invention includes a smaller amount of slip agent than is normally present in films used for similar applications, it also exhibits excellent adhesion of the ink applied thereto. The film of the present invention can be used to pack several products. It can be used especially for packaging food products, particularly wet food products such as, for example, many types of agricultural products. The film of the present invention can be especially useful in the packaging of cut lettuce, salad mixes, cut fruit, celery and the like. The following definitions apply unless expressly stated otherwise: "(meth) acrylic acid" includes acrylic acid and / or methacrylic acid; "interpolymer" refers to a polymer formed by the polymerization reaction of two or more different monomers and includes copolymers, terpolymers, tetrapolymers, etc .; "film" is used in its most generic sense to include all plastic weave materials, even when those having a thickness of 0.25 mm or less are more preferred; "inner layer" refers to a layer of a multilayer film having both principal surfaces directly adhered onto other layers of the film; "outer layer" means a layer of a film having one (or, in the case of a single layer film, none) of its principal surfaces directly adhered to another layer of the film; "inner layer" refers to an outer layer of a multilayer film which is, in relation to the other layers of the film, closest to the packaged product; "outer layer" refers to the layer of a multilayer film that is in relation to the other layers of the film, furthest from the packaged product; "Seal" means a bond of a first region of a film surface to a second region of a film surface created by heating (for example by means of a heated bar, hot air, infrared radiation, ultrasonic sealing, etc. .) of the regions to at least their respective seal initiation temperatures; "adhering" refers to the following: (a) when used in connection with two or more films, joining the films together by the use of a thermal seal or by other means such as, for example, a layer of adhesive between the films, or (b) when used in relation to film layers, joining a layer of subject film on an object film layer, without a bonding layer, adhesive, or another layer between them; "melt index", in accordance with what is described in ASTM 1238, is the amount of a thermoplastic resin that can be pushed through an orifice with a diameter of 0.21 cm (0.0825 inches) when subjected to a force of 2160 grams in 10 minutes at a specified temperature (for example, 190 ° C); "Total free shrinkage" refers to the change of percentage dimension in a film sample of 10 cm x 10 cm, when shrunk to 85 ° C, with the quantitative determination being carried out in accordance with ASTM of 2732. DETAILED DESCRIPTION OF MODALITIES ILLUSTRATIVES The film of the present invention includes a thermally sealable layer and a layer that includes an antiblocking agent (i.e., a vehicle layer). In one embodiment, the thermally sealable layer and the vehicle layer are the same layer. The thermally sealable layer of the film of the present invention includes one or more polymers having mer units derived from ethylene. Although an ethylene homopolymer may be employed, interpolymers are preferred. Exemplary interpolymers include those having mer units derived from one or more of propylene, C ^ -C20 alpha-olefins, vinyl acetate, (meth) acrylic acid, and C? ~ C2o esters of (meth) acrylic acid. Ionomers can also be used. The preferred interpolymers are ethylene / alpha-olefin interpolymers. For some applications, polyamides and / or polyesters may be employed in the thermally sealable layer. In addition, the polymers can be either heterogeneous or homogeneous. Heterogeneous polymers (for example those prepared with Ziegler-Natta catalysts) have a relatively wide variation in molecular weight and composition distribution. On the other hand, homogeneous polymers (for example, those prepared with single-site catalysts, such as for example metallocene) have relatively narrow distributions in terms of molecular weights and compositions. Ethylene / alpha-olefin interpolymers include both heterogeneous materials such as for example low density polyethylene (LDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), and very low density and ultra low density polyethylene (VLDPE and ULDPE), as well as homogeneous materials, preferably, the alpha-olefin is a C-C2c alpha-olefin, more preferably, a C4-C12 alpha-olefin, with even greater preference, a C4-C3 alpha-olefin. Alpha-olefins particularly include 1-butene, 1-hexene, 1-octene, and mixtures thereof. In general, from about 80 to 99% by weight of ethylene and from 1 to 20% by weight of alpha-olefin, preferably from about 85 to 95% by weight of ethylene and from 5 to 15% by weight of alpha-olefin they can be polymerized in the presence of a single site catalyst. Homogeneous ethylene / alpha-olefin interpolymers to be employed in a layer of the film of the present invention preferably have a molecular weight distribution of less than 2.7, more preferably from about 1.9 to 2.5, and especially from about 1.9 to 2.3. Homogeneous ethylene / alpha-olefin interpolymers typically exhibit an essentially unique melting point with a peak melting point (Tm), in accordance with that determined by differential scanning calorimetry (DSC) of about 60 ° C to 105 ° C, with greater preference of approximately 80 ° C to 100 ° C. The thermal seal layer polymer (s) containing (n) mer units derived from ethylene preferably include a homogeneous ethylene / alpha-olefin interpolymer having a density from about 0.85 to about 0.915 g / cubic centimeter, more preferably from about 0.88 to about 0.12 g / cubic centimeter, and especially from about 0.902 to about 0.908 g / cubic centimeter. The ethylene / alpha-olefin interpolymer also preferably has a melting point of about 65 ° to about 110 ° C, more preferably about 85 ° C to 110 ° C, and especially about 95 ° C to about 105 ° C. C. Homogeneous ethylene / alpha-olefin interpolymers inherently stickier, less dense, etc., than corresponding heterogeneous ethylene / alpha-olefin interpolymers. Due to these characteristics, they generally require the presence of more antiblocking agent than the corresponding heterogeneous ethylene / alpha-olefin interpolymers having the same degree of processing capacity. However, as shown, infra, the film of the present invention does not require containing a large amount of antiblocking agent to be easily processable. In general, when the film of the present invention has more than one layer, the thermally sealable layer can have a thickness from about 1 to about 75μm, preferably from about 2.5 to about 50μm, more preferably from about 5 to about 40μm, with even greater preference, from about 7 to about 25μm, and especially from about 10 to about 20μm. Although the packaging film of the present invention may have only one film layer (i.e., a thermally sealable layer according to that described above), at least one other layer may be preferred for certain end-use applications. When a multi-layer film is desired, the film can have any number of layers and any total thickness insofar as it provides the desired properties for the particular packaging operation where it should be used (eg, barrier properties, in free compliance, shrinkage tension, optical characteristics, modulus, seal resistance, etc.). Preferably, the film has no more than about 20 layers, more preferably no more than about 12 layers, and especially no more than about 7 layers. Thermoplastic films are used in various applications of food packaging and non-food products. The physical properties required of a film for any given end-use application often determine the composition of the film and / or the compositions of the various layers of the film. When several properties are required, several layers containing different polymer components can be employed and are usually employed. Persons with certain knowledge in the art are aware of the many polymer groups that may be employed in the other layer (s) than the stamp layer. Examples of such polymers include ethylene homopolymer, propylene homopolymer, ethylene / alpha-olefin interpolymers, propylene / ethylene interpolymers, ethylene / unsaturated ester interpolymer, styrene homopolymer, styrene interpolymers, ethylene / cycloolefin interpolymer. Frequently, mixtures of these and / or other polymers are used in order to optimize the properties offered by a single layer or to provide a single layer with various properties. For example, when gas barrier properties are desired, a layer including, for example, an ethylene / vinyl alcohol interpolymer (EVOH), vinylidene chloride interpolymer, or one or more polyamides can be included in the structure of the multilayer film. Certain barrier materials, such as EVOH, are known to be sensitive to moisture. When a film containing said barrier layer must be exposed to moisture, then one or more moisture barrier layers may also be included. If the film is likely to be subject to abuse during handling and / or transport, a layer of protection against abuse (either as an inner layer or an outer layer) can be provided. One or two sealable layers can be provided in order to allow sealing of the film on itself or on another packing joint during the formation of a package. One or more core layers can also be provided, and films with at least one core layer are preferred for many applications.

Especially when oxygen-sensitive products are packaged (ie products that have a shorter shelf life in the presence of too much or too little oxygen in the package, such as vegetables, fruits and cheeses), Providing a film that adequately transmits oxygen (and sometimes carbon dioxide) is a major concern. For example, in the package of pre-cut lettuce, the presence of an excess of oxygen results in enzymatic darkening of the cut surfaces, which is known as pink ribs. For part fillet, if the oxygen concentration is too low, the lettuce tends to spoil due to anaerobiosis. Therefore, when the product to be packed is sensitive to oxygen, care must be taken to ensure that the combination of the chosen layers offers the resulting film or packing with a sufficiently high oxygen permeation. Especially when used for packaging products such as agricultural products, the film of the present invention preferably has an oxygen permeation capacity, at standard temperature and pressure (STP), of about 0.006 to about 0.6 cubic centimeter / square meter , more preferably from about 0.009 to about 0.25 cubic centimeter / square meter 'S, still more preferably from about 0.01 to about 0.12 cubic centimeter / square meter * s, and especially from about 0.02 to about 0.09 cubic centimeter / square meter • s. A film with an OTR in one of the aforementioned ranges can be used in many agricultural product packaging applications. For other packaging applications, lower oxygen permeation capacities may be preferred. Many polymers including mer units derived from propylene or styrene can be employed in order to offer film layers with high oxygen permeation capacity. Examples of polymers containing mer units derived from propylene include propylene homopolymer (particularly oriented polypropylene) and ethylene / propylene copolymer, of the foregoing, oriented polypropylene and ethylene / propylene copolymer being preferred. Among the ethylene / propylene copolymers those containing from about 0.1 to 6% by weight of mer units derived from ethylene are preferred. Examples of styrene-containing unidadene-containing polymers include styrene homopolymer and styrene / butadiene interpolymers; among these, styrene / butadiene copolymers are preferred. When such polymers are present in a given layer, they preferably contain at least about 50% (by weight), more preferably at least about 75% (by weight) of this layer. In general, any core layer present may have a thickness of from about 2.5 to about 150μm, preferably from about 5 to about 100μm, more preferably from about 6 to about 60μm, preferably even greater from about 7.5 to about 25μm, and especially from about 10 to about 20μm. When the film of the present invention includes more than one layer, especially when it is to be used for applications such as agricultural product packaging, it is preferred that it has one of the following structures: A / B, A / B / A, or good A / B / C / B / A. In the aforementioned structures, A represents a layer that includes a polymer containing mer units derived from ethylene while B and C represent layers that include at least one polymer containing mer units derived from propylene or styrene. Additionally, a film having any of the aforementioned structures can be laminated onto another single layer or multiple layer film having any desired structure. Said lamination can be carried out by means of the application of adhesive or by means of crown lamination., both well known in the art. Examples of preferred multilayer film structures are A / B structures such as those described in U.S. Patent No. 5,523,136 (Fisher et al.), A / B / A structures such as those described in U.S. Patent No. 5,491,019 (Kuo) , and structures A / B / A and A / B / C / B / A such as those described in the copending US patent application number 08 / 597,790. The disclosures of each of the aforementioned documents are incorporated herein by reference. The film of the present invention preferably has a total thickness of from about 12.5 to about 250 μm, more preferably from about 15 to about 125 μm, preferably even more from about 20 to about 75 μm, and especially from about 25 to about 50 μm. When the film of the present invention includes 3 or more layers, at least one inner layer preferably has a Yung modulus greater than the Yung modulus of the thermally sealable layer. The film of the present invention preferably has a global Yung modulus of at least about 275 to about 1400 MPa, more preferably about 350 to about 1025 MPa, preferably even greater than about 500 to about 875 MPa and especially about 550 to about 775 MPa. Regardless of the number of layers present in the film of the present invention, at least one of the layers includes a dispersed antiblocking agent. Antiblock agents are generally recognized as finely divided infusible solids which, when incorporated into a film, provide asperities protruding from one or both of the primary surfaces of the film. The air spaces that result from these roughness interfere as it is believed with the surface (s) of the film that adhere to each other. Likewise, antiblocking agents offer a beneficial "rolling" effect when the film is passed through metal parts in typical commercial packaging equipment. The antiblocking agents can be incorporated in an outer layer in order to offer the aforementioned asperities. However, relatively large particles used for anti-blocking purposes can be incorporated into an inner layer of a film. Antiblock agents useful in the film of the present invention may include inorganic materials based on minerals and / or synthetics. Mineral-based antiblocking agents include both silica-based agents (e.g., diatomaceous earth, aluminum silicates, silicon dioxide, quartz, glass, and silica sand), as well as others such as kaolin, talc, feldspar, and calcium carbonate. Synthetic antiblock agents include synthetic gel-like and precipitated-type silicas. Preferred inorganic antiblocking agents include aluminum silicate (ie, clay), silica, sodium calcium aluminosilicate, magnesium silicate (talc), and calcium silicate, particularly aluminum silicate, silica, sodium calcium aluminosilicate, and silicate of magnesium. Antiblock agents useful in the film of the present invention may also include crosslinked or non-crosslinked organic materials. Examples include polyesters, EVOH, polyamide 6, polyamide 66, syndiotactic polystyrene, poly (methyl methacrylate), liquid crystalline polymer, and spider resins. The selection of an appropriate anti-blocking agent depends at least in part on the nature of the layer in which the antiblocking agent is to be included. For example, the Vicat softening point of any organic antiblocking agent used is preferably greater than the Vicat softening point of the polymer (s) of the carrier layer. The above-mentioned antiblocking agents can have a median particle size (diameter) of from about 0.1 to about lOμl, more commonly of approximately 1 to about 8μn, and preferably about 2 to approximately 6μm. Regardless of identity and size, the antiblocking agent is preferably in the form of approximately spherical particles, even when particles of irregular and angular shapes can also be employed. Alkaline aluminosilicate ceramic particles are a preferred type of antiblocking agent, particularly ceramic particles having a refractive index of about 1.52. Alkaline aluminosilicate ceramic particles useful as an antiblocking agent in accordance with the present invention are available in various sizes and size distributions. The preferred alkaline aluminosilicate ceramic particles are the ZEEOSPHERE® microspheres (Zeelan Industries, Inc., St. Paul, Minnesota). The antiblock agent is preferably present in the film of the present invention at a level of 0.025 to about 6% (by weight), more preferably from about 0.05 to about 4% (by weight), and especially about 0.075. about 2.5% (by weight), with each of the aforementioned percentages based on the weight of the carrier layer. However, when using alkaline aluminosilicate ceramic particles as the antiblocking agent, they preferably constitute only up to about 0.1% (by weight) of the carrier layer and not more than about 0.3% (by weight of the overall film). (Lower load levels may be employed due to the relatively larger size of such particles). A preferred charge level is from about 0.05 to about 0.75% (by weight), more preferably from about 0. 075 to about 0.5% (by weight) of the film. More preferably, when ceramic micro spheres are employed, they are present in an amount of about 0. 1 to about 0. 3% (by weight). In addition, the amount of antiblocking agent included in the carrier layer (s) may depend on the desired COF and cloudy values for the film and the size of the particles used. Specifically, when the particles have an average diameter of up to about 5.5μm (such as for example ZEEOSPHERE® -210 microspheres, which are said to have a median diameter of approximately 3.5μm), are preferably present in an amount of at least about 0.05% by weight. However, when the particles have an average diameter of more than about 5.5μm (such as for example ZEEOSPHERE® W-410 microspheres, having a median diameter of about 4.5 to about 5.Oμm) at least about 0.01% by weight of particles It can provide the desired balance of COF and cloudy properties. Alkaline aluminosilicate ceramic particles (ie, microspheres) can produce a relatively large reduction of the COF of a film where they are incorporated at relatively low loading levels. The reduction in the amount of anti-blocking agent employed can substantially reduce the accumulation of negative elementsO-S. In general, accumulation is an accumulation of film additives on one or more surfaces of the packaging equipment which is caused due to repeated friction between the surface (s) and the film, particularly when the packaging equipment is Handles at high speeds. Accumulation frequently presents a significant problem during a package operation because it tends to detach from the equipment surface (s) and / or the packages being formed. At a minimum this results in packaging that does not present an aesthetic appearance and, in the case of food packaging, this may result in legal concerns regarding food. Film additives that can contribute to the buildup include various additives but, particularly, antiblocking agents and slip agents. Equipment surfaces can be cleaned frequently in order to avoid packing failures caused by accumulation; however, repeated cleaning can result in a significant amount of downtime for many packaging operations. Accordingly, it is highly desirable to reduce the amount of antiblocking agent and slip agent present in the packaging film while maintaining the good processability of the overall film. Certain types of alkaline aluminosilicate ceramic particles may appear white to the naked eye. These particular ceramic particles have a refractive index of about 1.52. therefore, in certain preferred embodiments, the supply of an overall carrier and / or film layer with a refractive index of at least about 0.50, more preferably a refractive index of about 1.50 to about 1.54, with an even greater preference Refractive index of about 1.52 (ie, as close as possible to the ceramic particles) may be preferred. Polyolefin materials generally have refractive indexes within a range of about 1.46 to about 1.54 and are therefore preferred materials for the various layers of the film. More specifically, interpolymers including mer units derived from ethylene advantageously have refractive indices in the vicinity of the refractive indices of the ceramic particles described above. When the thermally sealable layer is also the carrier layer, the refractive index of the thermally sealable layer is at least about 1.50, more preferably about 1.50 to about 1.54. said similarity in refractive indexes between the carrier layer and the anti-blocking agent normally results in the film with excellent optical (ie, clear- and cloudy) properties. As mentioned above, the film of the present invention requires a significantly lower amount of slip agent to achieve the same degree of processability as previously available films. In some circumstances, the film of the present invention may include a slip agent in an amount not greater than about 500 ppm, not greater than about 400 ppm, not greater than about 300 ppm, not greater than about 200 ppm, not greater than about 100 ppm, not more than about 50 ppm, and not more than about 25 ppm. In one embodiment, the film of the present invention can be essentially free of slip agent. In no case the film of the present invention includes more than about 800 ppm, preferably not more than about 750 ppm, more preferably not more than about 700 ppm, preferably even higher, not more than about 650 ppm, preferably still greater not more than about 600 ppm, and especially, not more than about 550 ppm. When the film of the present invention includes at least 3 layers, the slip agent may be present (if present) in an inner layer or an outer layer of the film. Frequently employed slip agents that are also present in the film of the present invention include fatty amides, waxes, polytetrafluoroethylene, and the like. When a fatty amide is used as the slip agent, it can be a primary, secondary, or tertiary amide; a fatty alkanolamide; or a fatty bisamide. Preferably, any fatty amide employed is selected from erucamide, stearamide, oleamide, behenamide, and ethylene bisestearamide. A more detailed commentary on the fatty amides can be found in McKenna, Fatty Amides (Fatty Amides), 1992 (itco Chemical Corp.) which is suggested to refer the reader for more information on the subject of useful amides. The film of the present invention also includes an anti-clouding agent coated on the thermally sealable layer. Those of ordinary skill in the art will understand that antifogging agents are normally placed on the surface of a package that is closest to the product (i.e., the inner surface). Due to the manner in which numerous packages are made from the films, the appropriate surface is usually the thermally sealable layer.

Anti-fume agents which can be used in combination with the film of the present invention generally fall into such broad classes as esters of aliphatic alcohols, polyesters, polyhydric alcohols, polyhydric aliphatic alcohol esters, and polyethoxylated aromatic alcohols Jincluding phenols). Commonly used anti-clouding agents include materials such as polyoxyethylene, sorbitan monostearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene monopalmitate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan trioleate, poly (oxypropylene), polyethoxylated fatty alcohols, polyoxyethylated 4-nonylphenol, polyhydric alcohol, propylene diol, propylenetrol as well as ethylene diol. Preferred antifogging agents in the film of the present invention include monoglyceride esters of vegetable oil or animal fat, monophenyl polyethoxylate, distilled or undistilled glycidyl monooleate, as well as sorbitan monolaurate. Sorbitan monolaurate is especially preferred, either alone or in combination with one or more of the foregoing. Instead of being applied directly on the thermally sealable layer or instead of being mixed into the mixture from which the thermal seal layer is derived, the anti-clouding agent is trapped in a binder. More specifically, the anti-clouding agent is bonded to a polymeric material that is applied to the outer surface of the thermally sealable layer. Although many types of polymers can potentially be used as binder, those containing mer units derived from an ester of (meth) acrylic acid or vinyl acetate are especially useful. Preferably, the binder includes a polymer containing mer units derived from an ester of acrylic acid and / or a polymer containing mer units derived from ethylene and vinyl acetate (for example, an ethylene / vinyl acetate copolymer). Polymers containing mer units derived from an acrylic acid ester are particularly preferred as binders in the film of the present invention. Regardless of the type of polymer (s) in the binder, the polymer (s) preferably include a slip agent in an amount no greater than previously specified. The relative amounts between antifogging agent and binder can vary greatly and, to a certain extent, depend on the identity of the antifogging agent and the binder chosen. However, the ratio between antifogging agent and binder is within a range of from about 1:10 to about 10: 1, preferably from about 2: 3 to about 5: 1, and especially from about 1: 1 to about 2: 1 Even when it is unnecessary for the effectiveness of the binder-antifogging agent mixture, one or more solvents may be present. In some circumstances, the present solvent having a relatively low boiling point is relatively non-polar. Examples of preferred solvents include acetates (e.g., ethyl acetate, n-propyl acetate, and the like) and various alcohols (e.g., ethanol). In addition, although it is unnecessary for the effectiveness of the binder-antifouling agent mixture, silica may be included in the mixture. Mixtures containing silica can offer anti-blocking properties to the coating. The antiblock mixture can be applied to the film by any known coating method including, not limited to these, flexographic, engraved, plate, and the like. Regardless of the manner of application on the film of the present invention, a coating of the anti-clouding mixture may have a thickness of from about 0.25 to about 5μm, preferably from about 0.1 to about 2.5μm, more preferably from about 0.25 to about lμm . An especially preferred film according to the present invention has an anti-blocking agent present on a first external surface of the film and printed on the other outer surface of the film. Since the film of the present invention includes a relatively small amount of slip suede and includes anti-clouding agent bonded to a polymeric matrix on the opposite side of the film, a printing ink adheres normally well (i.e. does not detach ) on the film or on a packaging made from the film. Also, a surface treatment of the film at the time of manufacture or after manufacture (for example, by corona, plasma, or similar treatment), can result in a film having increased ink adhesion. Preferably, the film of the present invention has an external surface (i.e., a surface on which a print can be applied) having a surface energy of at least about 0.038 J / square meter, more preferably at least about 0.040 J / square meter and especially at least approximately 0.042 J / square meter. Generally, the printing ink will adhere to these films at a level of at least about 80% in accordance with that measured with a standard pressure sensitive tape test known to those of ordinary skill in the art. To protect printed images on the outer surface of a film "of the present invention, the film can be laminated on another film in such a way that the image is trapped between the two films.Alternatively, the printed film can be protected with a polymeric coating. Said coating preferably includes a polymer with mer units derived from an ester of (meth) acrylic acid, particularly an ester of acrylic acid, In addition, said coating can include up to about 1% by weight of silica based on the weight of the coating The silica can help to space the coated layer of the adjacent layer when the film of the present invention is rolled in. The film of the present invention in untreated form (ie, when not corona treated) exhibits preference a kinetic COF when in contact with a metal surface (according to the medical compliance with ASTM 1894-95, which is incorporated herein by reference) not greater than about 0.50, more preferably, no greater than about 0.40, preferably even greater, no greater than about 0.35, and especially not more than about 0.33. Kinetic COFs from 0.30 to 0.32 can easily be achieved with films in accordance with the present invention. According to the number- and type of layers included and the manner in which it is made, the packaging film of the present invention can be used for various purposes. The film of the present invention can be manufactured per various processes well known in the art. The particular process chosen will normally depend on the final use of the material. For example, when the material is to be used as shrinkable film, various blow-bubble manufacturing techniques can be employed. A person with ordinary knowledge in the art can propose various coating processes by extrusion, free film extrusion, film blowing process, etc. The film of the present invention can be oriented andWhen it is oriented, it is preferably oriented and biaxially oriented. Said film is preferably biaxially oriented and heat shrinkable. The oriented film has been elongated, generally at elevated temperature (i.e., orientation temperature), then adjusted or blocked in elongated configuration by cooling. This configuration of elongation at high temperature followed by cooling causes an alignment of the polymer chains in a more parallel configuration, whereby the mechanical properties of the film are dramatically altered. When a non-tempered, unrestrained oriented film is subsequently heated to its orientation temperature, the film shrinks almost to its original dimensions, that is, before the elongation. Said film is known as heat shrink. Frequently, the term orientation ratio (ie, the product of the extent to which the film is oriented in several directions, usually two perpendicular directions between them) is employed when describing the degree of orientation of a given film. The orientation in the direction of the machine is known as "pulling", while the orientation in the transverse direction is known as "stretching". In the case of films excluded through an annular die, the stretching is obtained by blowing the film to produce a bubble. In the case of films of this type, the pulling is obtained by passing the film through two sets of driven throttle rollers, with the downstream assembly having a higher surface velocity than the upstream assembly. The resulting stretch ratio is the surface velocity of the downstream throttle roller assembly divided by the surface velocity of the upstream throttle roller assembly. When the film of the present invention is biaxially oriented, it can be used to produce bags for packing fresh red meat, smoked and processed meat, pork, cheese, poultry, and the like, in accordance with what is described, for example, in U.S. Pat. 3,741,253 (Braxed et al.), 3,891,008 (D'Entremont), 4,048,428 (Baird), and 4,284,458 (Schirmer). It can also be used as shrinkable film in packaging applications for packaging food and non-food items such as described, for example, in U.S. Patent Nos. 4,551,380, and 4,643,943 (both to Schoenberg). The packaging film of the present invention may have an oxygen, moisture or odor barrier functionality, as described, for example, in U.S. Patent Nos. 4,064,296 (Bomstein et al.), 4,724,185 (Shah. ), 4,839,235 (Shah), and 5,004,647 (Shah). When a barrier layer is included, the packaging film of the present invention can be used in applications in which the packaged product (s) must be protected against one or more harmful materials (e.g. , 02 atmospheric). More particularly, the material of the present invention can take the form of the stretch film, suitable film for final use of form filling and vertical or horizontal seal, film for lid, film suitable for vacuum film packing, film suitable for use as a barrier bag, film suitable for use as a patch bag in accordance with that presented, for example, in U.S. Patent Nos. 4,755,403 and 4,770,731 (both from Ferguson), film suitable for use in ready-to-use packages, film suitable for use in a thermally formed container (particularly a film used as a liner in a polystyrene tray), barrier film to the aromas / odors, film suitable for use in end-use cooking applications (especially heat shrinkable bags, heat-shrinkable and non-shrinkable cases, as well as thermoformed containers made from non-shrink films and sheets), as well as medical film. The films of the present invention can be irradiated to induce crosslinking. In the process of irradiation, the film is subjected to a treatment of energetic radiation, such as discharge corona, plasma, flame, ultraviolet radiation, X-rays, gamma rays, beta rays, and treatment with high-energy electrons, which induces crosslinking between molecules of the irradiated material. The appropriate level of dosage can be determined by standard dosimetry methods known to those of ordinary skill in the art, and the precise amount of radiation to be used depends obviously on the particular structure and its end use. When the film is irradiated, it is preferably exposed to from about 0.5 to about 15 megarads (MR), more preferably from about 1 to about 12 MR. Gas permeations to produce packaging films have traditionally been adapted to a desired level by varying the overall thickness of the multilayer film. That is, to achieve a desired relatively high residence to oxygen, a thinner film is produced. This decrease in caliber is often effected at the expense of film strength and resistance to abuse. Conversely, film structures that are resistant to abuse and that can be easily processed generally do not exhibit the desired level of gas permeability or seal properties required for applications such as vertical form-fill-seal equipment ( VFFS). However, the film of the present invention combines resistance against abuse and relatively high oxygen permeation. In addition, the use of the film of the present invention in VFFS equipment results in a very low percentage of packages having defective seals. The desirable processing characteristics of the multilayer film of the present invention allows for higher packaging speeds in VFFS equipment, as well as other packaging machinery. These desirable processing characteristics extend to other packaging operations in which the film is used as a lid, packing material, etc. The higher packaging speeds are due to the low seal temperature and the high hot tack strength characteristics of the multilayer film of the present invention. In carrying out the packaging process of the present invention, any VFFS machine employed preferably forms, fills and seals at least 15 packages per minute without substantial defects in the film in the seals. A team of VFFS is well known by people with certain knowledge in the field of packaging. As mentioned above, the film of the present invention is particularly adapted for use with oxygen sensitive products. Examples of oxygen sensitive products that can be packaged in the film of the present invention include, but are not limited to, head of lettuce, lettuce leaf, lettuce leaf, cabbage, broccoli, green beans, cauliflower, spinach, cabbage, carrot, Onion, and radish. When the film of the present invention has an oxygen permeation (in STP) of from about 0.02 to about 0.2 cubic centimeter / square meter -s, more preferably from about 0.03 to about 0.07 cubic centimeter / square meter * s, the product a Packing includes preferably at least one of the following: lettuce head, lettuce leaf, cabbage, green bean, cabbage, carrot, onion, and radish. The objects and advantages of this invention are further illustrated through the following examples. The particular materials and quantities thereof, as well as other conditions and details, mentioned in these examples, should not be used to unduly limit the invention. EXAMPLES Example 1: Manufacture of film structures A. Three-layer coextruded film A co-extruded non-oriented film having an average thickness of approximately 51μm was produced in a conventional hot-blown film equipment equipped with a multilayer annular die with the object of producing a film having a structure of type A / B / A. Layer "A" was made from a mixture containing 71.6% (by weight) of homogeneous ethylene / hexene copolymer D139 (Phillips Chal Co; Houston, TX) with a density of 0.918 g / cubic centimeter, and a melt flow index (190 ° C, 216 kg) of 0.9 g / 10 min; 25.0% (by weight) of LDPE 607 A (Dow Chemical Co., Freeport, TX) which has a density of 0. 924 g / cubic centimeter and a melt flow index of 2. 0 g / 10 min; 1.4% (by weight) of SSABC-2575TTD-2 masterbatch consisting of slip / antiblocking agent / processing aid (Plyfil Corp., Rockaway, NJ); and 2.0% (by weight) of antiblocking concentrate LR-89602 (Ampacet Corp, Tarrytown, NY). This layer was corona treated in line in the blow-through processing step such that the layer had a surface energy of approximately 0.037 to 0.040 J / square meter, thus making the surface receptive to ink systems for printing on the surface, based on solvents. Layer "B" was made from propylene / ethylene random copolymer PP 9122® (Exxon Chemical Ce, Baytown, TX), which has a nominal density of 0.900 g / cubic centimeter, a melt flow index (230 ° C, 216 kg 'of 2.1 g / 10 min, and an ethylene content of (nominally) 2.0% by weight The "C" layer was made from a mixture that includes 69.8% (by weight) of a homogeneous ethylene / hexene copolymer Exact® SLX-9107 (Exxon Chemical Co.) which has a density of 0.910 g / cubic centimeter and a melt flow index (190 ° C, 2.16 kg) of 1.2 g / 10 min; 25.0% (by weight) of LDPE 607 A which has a density of 0.924 g / cubic meter and a melt flow index of 2.0 g / 10 min; 3.2% (by weight) of a master slip agent block, anti-blocking / auxiliary processing; and 2.% (by weight) of anti-blocking concentrate 10917 (Ampacet Ccrp.). The mixtures of layers A, B and C were. fed in separate extruders. The melted homogenized layers were co-extruded through an annular extrusion die and blown to a desired thickness while cooling simultaneously with an external air ring and with an internal bubble cooling stack. The cooled multilayer film was collapsed, glued and coiled on cores for further processing. B. Single layer film A single layer film having an average thickness of approximately 56 μm was produced by means of a conventional blow extrusion process. The mixture includes 72.5% (by weight) of homogeneous ethylene / hexene copolymer D139 (Phillips Chemical Co.); 25.0% (by weight) of LDPE 607 A (Dow Chemical Co.); 1.5% (by weight) of master slip agent / anti-blocking / processing aid; and 1.0% (by weight) of anti-blocking concentrate 10917. The homogenized, melted mixture was extruded through an annular blown film extrusion die, and blown to a desired thickness while cooling simultaneously with an external air ring. One was achieved - Gauge randomization with an oscillating die while a conventional covered wooden tablet structure achieved the lapse of the bubbles. The collapsed, relatively cold tube was then corona treated at a surface energy of approximately 0.037 to 0.040 J / square meter, causing the receiving surface to solvent-based surface printing ink systems. The cooled film was folded, and wound on core for further processing. The film presented an excellent balance -between optical characteristics, sealing capacity, resistance, and cost. C. Laminated Film Including Biaxially Oriented Polypropylene (BOPP) A 23μm thick BOPP 343 AA22 film (Amtopp Corp., Livingston, NJ) with a printed, treated side was laminated on a similar 43μm single layer blown film to the layer that has just been described above. This last film was made from a mixture of 70.65% (by weight) of a homogeneous ethylene / hexene copolymer 350D60 from Exceed® (Exxon Chemical Co.) with a density of 0.917 g / cubic centimeter and a melt flow index ( 190 ° C, 2.16 kg) of 1.0 g / 10 min, 17.0 g (by weight) of LDPE with a density of 0.24 g / cubic centimeter and a melt flow index of 2.0 g / 10 min, an homogeneous ethylene / hexene copolymer SLX -9090 Exact® (Exxon Chemical Co.) with a density of 0.902 g / cubic centimeter and a melt flow index (190 ° C, 2.16 kg) of 1.2 gm / 10 min and 2.25% (by weight) of a batch slip agent / anti-blocking master / process assistant. The two films were laminated using a solvent-free two-component adhesive. The adhesive includes 1.6 parts of isocyanate component 7975 Liofol® (Liofol Co.; Cary, NC) and 1.0 part Liofol component 7276 LiofolS (Liofol Co.). The adhesive was applied to the printed BOPP surface by means of an applicator roll at a coating weight of 1.2 to 2.2 kg per ream. The other film was contacted with the BOPP surface coated with adhesive on a choke roller. The rolled product was rolled into master rolls and the square was allowed 24 to 48 hours before the roll width cut. D. Laminated film including a two-layer co-extruded film A two-layer co-extruded film was prepared from two different mixtures. The first layer of 18.5μm thickness was made from a mixture containing 98% (by weight) of styrene / butadiene copolymer 684D-Q188 a Styrolux® (BASF; Mount Olive, NJ) and 2.0% (by weight) of slip concentrate SKRH-10 (A. Schulman Co .; Akron, OH). The second 8.2μm layer was made from a mixture of 84.5% (by weight) of homogeneous ethylene / butene copolymer 3125 Exact® (Exxon Chemical Co.) with a density of 0.910 g / cubic centimeter and a melt flow index of 1.2 g / 10 min, 10.0 g (by weight) of LDPE with a density of 0.924 g / cubic centimeter and a melt flow index of 2.0 g / 10 min, 3.5% (by weight) of master batch of slip / anti-blocking / auxiliary processing and 2.0 (by weight) of a master batch of polymer processing aid (Ampacet Corp). The outer surface of the second layer was corona treated in line in the coextrusion processing step by blowing in such a way that the layer had a surface energy of approximately 0.040 to 0.044 J / square meter, thus making the receiving surface for solvent-based reverse injection ink systems. The film was subsequently flexo printed flexographically on the treated surface. The coextruded, printed film was then adhesively laminated onto a 51um thick single layer film made from a mixture of 77% (by weight) of a homogeneous ethylene / hexene copolymer 350D60 Exceed ® with a density of 0.910 g / cubic centimeter and a melt flow index of 1.2 g / 10 min, 20.0% (by weight) of LDPE with a density of 0.924 g / cubic centimeter and a melt flow index of 2.0 g / 10 min, 2.25% (by weight) of a slip / anti-blocking agent / auxiliary processing master batch, and 0.75% (by weight) of anti-blocking concentrate 10917. The two films were laminated and processed in accordance with that described above. Example 2: physical properties of films. The four films of example 1 were tested in several ways. The results of these tests appear in the table immediately below. Table 1 ACD Thickness of layer (s) 13/25/13 56 23 // 2.5 // 43 27 // 2.5 // 51 μm Permeation of oxygen0.032 0.039 0.0 0.028 geno (at 23 ° C and 101-Kpa), cm3 / m2, s Tackness ca800 825 150 475 spike peak, g Temperature 190 225 22 230 start of seal, ° C cloudy,% 8 7 11 12 Brightness (45 °) 80 75 80 90 Example 3: coating and performance test Single layer films such as those described above in section B in Example 1 containing 200 ppm of erucamide slip agent were corona treated in line to achieve a surface energy of 0.034 to 0.040 J / square meter before coating. Using a standard printing press, these films were coated with the formulations described in table 2 below. The terpolymer binders used in the coatings were either an OPV Contax® acrylate resin (Sun Chemical Co., Winston-Salem, NC), an ethylene / vinyl acetate copolymer (EVA) resin 33-131 Adcote® (Morton International, Inc., Chicago, IL), or, as a comparison, a polyvinyl acetate resin AYAT® (PVA) (Union Carbide Corp., Danbury, CT). The anti-clouding agents employed were glyceryl monoleate (Division of Polymer Additives Pateo and American Ingredients Co., Kansas City, MO), then GMO; sorbitan monolaurate 20 S-MAZ® (Sun Chemical Corp.), below SMO; and (3) polyethoxylated nonifenol 6961 Trycol® (Henkel Co., Ambler, PA), then PNP. W500 Syloid® silica (W.R. Grace &Co., Baltimore, MD) was used as an antiblocking agent in some films. Coating formulations were prepared by mixing binder, anti-clouding agent (s), and additives, followed by dilution with a mixture of volatile solvents such as a 50:50 mixture of ethyl acetate and n-propyl acetate. After the coating of the films, the anti-clouding performance of The coatings were evaluated. The films were formed into packages which were filled with lettuce using a VFFS machine. His performance was rated several times on a scale of 1 to 5 where a rating of 3.5 to 4 indicates outstanding resistance to cloudy formation and a rating of 4.0 or higher indicates excellent resistance to cloudy formation (it is a good test known as published by ICI.) Table 2 Anti-Aging Agent Anti- Proportioning agent in- (P) cloudy (A) cloudy (B) tre P: A: B GMO SMO acrylate 3: 2: 1 acrylate * GMO SMO 3 : 2: 1 GMO SMO acrylate 3: 2: 1 GMO SMO acrylate 3: 2: 1 EVA GMO SMO 3: 2: 1 Acrylate GMO SMO 2: 1: 0 Acrylate GMÓ SMO 2: 0: 1 Acrylate PNP SMO 2: 1: 0 PVA GMO SMO 3: 2: 1 None none none N / A Binder (P)% of total silica Performance of substances ( s / s) 4.24.48 hrs. Non-volatile Acrylate 10 3.75, 4.4 acrylate * 15 4.4.25.4.75 acrylate 15 4.4.4.4.4 acrylate 15 4, 4, 3.75 EVA 15 3.75, 3.6, 3.6 Acrylate 15 3.75.3.5.3.75 Acrylate 15 4.3.4.5.4.7 Acrylate 15 4.3.4.9.4.5 Outstanding PVA none N / A 1.3.2.1.9 * Contained 500 ppm erucamide slip agent The data in table 2 show that the Several coatings, all of which presented ratings within a range of "excellent" to "excellent", performed better than the uncoated control sample. Coated films that did not include any antiblocking agents in the coating were slightly more sticky, with the PVA coating being too sticky for normal processing in standard packaging equipment. Films with silica added to the coating exhibited a reduced tack and a less tendency to block. Overall, the films were difficult to process in VFFS machinery due to the relatively low level of slip agent added to the films during extrusion. Laminated products similar to those described in sections C and D of Example 1 and co-extruded multi-layer films similar to those described in section A of example 1 exhibited performance and processing characteristics similar to the observed characteristics presented above. Example 4: Addition of micro-spheres Films were prepared as those tested in Example 3 but incorporating 2,000 ppm of Zeeosphere ® hollow ceramic microspheres while reducing the amount of erucamide slip agent. Four films were prepared containing the following amounts of slip and antiblock additives: Silica (ppm) Talc (ppm) Erucamide (ppm) 2400 0 400 0 __3600 0 0 3600 200 0 3600 400 These films were coated as in Example 3 with the following anti-clouding formulation: 25 parts by weight of V-acrylate OPV Contax® 4 parts by weight of SML 0.6 parts by weight of silica 500 Sylod® 70.4 parts by weight of a 50:50 mixture of ethyl acetate and n-acetate propyl films were printed on one side and applied in line on the other side, using a printing press equipped with an inline coating device. The level and treatment on the coating side was adjusted in order to provide a surface energy of approximately 0.036 J / square meter. These films exhibited reduced metal to film friction during the machining of the film on a VFFS equipment. The films were later set aside for 3 days before their cut. During cutting, the films were monitored to determine the presence of blocking or transfer (of coating the surface applied to the opposite film surface) on the roll. (A coating transfer usually occurs when blocking is important.) No transfer of coating was observed with any of the films. The film that did not contain a slip agent showed a certain blockage but no transfer of the coating on the side of the face. Example 5: Different Sliding Agent Two films similar to the films of Example 4, except that hydroxierucamide was used as a slip agent instead of erucamide, were prepared. (Hydroxierucamide migrates towards film surfaces more slowly than erucamide). These films had 2000 ppm of microspheres and 3600 ppm of silica. One of the films included 200 ppm of hydroxycerucamide while the other included 400 ppm of hydroxycerucamide. The films were coated in the same manner as the films of Example 4. No coating transfer was observed, even though a certain blocking was observed with the film containing 200 ppm hydroxyureucamide. It is believed that this is due to its relatively slow speed of migration towards the surface of the film. Several modifications and alterations that do not go beyond the scope and spirit of the invention are apparent to people with experience in mate: This invention should not be considered as limited the illustrative modalities presented here.

Claims (10)

1. CLAIMS 1. A packaging film comprising one or more layers, said film comprising: a) a thermal seal layer comprising a polymer comprising mer units derived from ethylene; b) coated on said thermally sealable layer, there is at least one anti-clouding agent placed in a binder, said binder comprises a polymer comprising mer units derived from at least one of the following: an ester of (meth) acrylic acid and monomers of vinyl acetate; and c) an antiblocking agent dispersed in at least one layer of said film, said film comprising no more than about 800 parts per million slip agent.
2. 2. The film according to claim 1, wherein said slip agent is present in an amount of no more than about 750 parts per million.
3. 3. The film according to claim 1, wherein said slip agent is present in an amount of no more than about 500 parts per million.
4. 4. The film according to claim 1, wherein said slip agent is present in an amount of no more than about 200 parts per million.
5. 5. The film according to claim 1, wherein said antiblocking agent is present in said thermally sealable layer.
6. 6. The film according to claim 1, wherein said antiblock agent is present in an amount of between about 0.1 and about 6% by weight, based on the total weight of the film layer in which said agent is placed. of antiblocking.
7. 7. The film according to claim 1, wherein said antiblocking agent is constituted by ceramic particles of alkaline aluminosilicate.
8. The film according to claim 1, wherein said binder comprises a polymer containing mer units derived from an ester of acrylic acid.
9. 9. The film according to claim 1, wherein said binder further comprises silica.
10. 10. A method for packaging a product comprising: a) introducing the product into a bag made from the film of claim 1, b) sealing the bag in order to form a package.