MXPA99006645A - Printed polymeric film and process for making same - Google Patents

Abstract

A printed film includes a substrate film with a surface polymeric layer that includes a thermoplastic polymer having at least one of a melting point and a Vicat softening point of no more than about 130°C and, on a surface of the film, a printed image in the form of a polymeric film. The substrate film can be printed without chemically and/or oxidatively priming the surface to be printed and exhibits superior retention of the image after undergoing heat treatment.

Description

PRINTED POLYMERIC FILM AND PROCESS FOR ITS PREPARATION GENERAL INFORMATION 1. Field of the Invention This invention relates to printed polymeric films, more particularly to polymeric films with a printed image. 2. BACKGROUND OF THE INVENTION In the printing of flexible packaging materials (e.g., thermoplastic films and laminated products), techniques are commonly employed that allow the printing of a static image (i.e., that does not change) quickly. Even though these techniques, including flexography, result in a very high number of images per unit of time once started, their preparation procedures are often time-consuming, complex and expensive. To test a new design image, the entire printing process must be stopped, altered, and restarted. If the resulting image does not correspond to what was planned, additional modifications are required. Rapid printing techniques allow printers and their customers to carry out an almost unlimited number of changes to a given printed image and do so essentially instantaneously. Thus, such techniques are ideal for custom and / or specialty printing (ie, when they should print a limited number of pages with a design, image, text, etc., given), especially when more than one color should be included. One such technique is digital printing represented, for example, by the tissue press DCP-1 (Xeikon, Mortsel, Belgium) and the digital offset press E-Print® 1000 (Indigo N.V., Maastricht, the Netherlands). Recently, fast printing methods were adapted for use with flexible packaging materials, especially polymeric films. Such films typically have the form of continuous fabrics and not discrete sheets. New digital presses specifically designed for use with polymeric films have been developed. An example of a press of this type is the O nius ® color press (indigo, N.V.). Despite the fact that said printing presses have been developed, the surface layers of such films (where the printing is carried out) must be prepared before printing. For example, a student of this technology raised the following 'the indigo system has been printed on several films but to provide good adhesion, it is necessary to apply a surface preparation product or a modification of the surface of the film " Podhajny, * echnical Report: Revealing the mystery behind digital printing ", Converting Magazine, October 1996 to 79. Even though surface modification techniques (for example, flame or corona treatment, polish, etc.) can be used to prepare a surface of a polymeric film for printing, the application of a Preparation chemical coating is the most common. Substrates of polymeric films frequently used with digital color presses, such as, for example, the Omnius ® color press, include polyesters (3M, St. Paul, MN) as well as oriented polypropylenes (Mobil Chemical Co; Macedon, NY). Both products, as well as other films commercially available for use with these preparation substances, require the application of a preparation substance before printing. To further complicate the problem, many polymeric films are thermally treated (eg, thermal shrinkage) before their final use. Such treatment may occur in a hot water bath (e.g., at a temperature of 80 ° C or more), a hot air tunnel (e.g., at a temperature of about 140 ° C or more), or in a steam tunnel. Unfortunately, heating printed polymer films often causes the printed image to be de-laminated from the film. This may be due to the effect of entrained solvents that soften the ink system, thus decreasing the adhesion of the ink on the film. This decreased adhesion makes the printed film more susceptible to abrasion and / or transfer of the printed image to another surface. In severe cases, the ink can completely separate from the substrate. The use of a polymeric film substrate without application of preparation agent or without treatment, particularly a film substrate useful for food packaging and which can maintain a good adhesion to the image even when it is in a heated state, in a process Color printing has not been previously described. SUMMARY OF THE INVENTION In summary, the present invention offers a printed polymer film that includes a substrate film that includes a surface polymer layer and, in the surface polymer layer, a printed image in the form of a polymer film. The surface polymer layer includes a thermoplastic polymer having a melting point no greater than about 130 ° C and said surface polymer layer receives no treatment through chemical agent and oxidant. In another aspect, the present invention provides a printed polymer film consisting essentially of a substrate film that includes a surface polymer layer and, on the surface polymer layer, an image printed on the surface. shape of a polymeric film. The surface polymer layer includes a thermoplastic polymer having a melting point no greater than about 130 ° C. In a further aspect, the present invention provides a process for making a printed polymer film. The process includes the step of transferring a polymer film image from a heated plate to a substrate film surface. The substrate film includes a surface polymer layer that includes a thermoplastic polymer having a melting point no greater than about 130 ° C. The surface polymer layer receives no chemical treatment or preparation oxidant. A printed polymer film made by this process is also provided. The substrate film of the present invention may include more than one polymeric layer, that is, it may be a multilayer film. Likewise, the film may be supported on a sheet material such as another polymer film. The film of the present invention can, if desired, be printed on both primary surfaces. The printing of the second surface can be carried out in accordance with the process of the present invention to the extent that the second surface also includes one or more thermoplastic polymers having melting points not greater than about 130 ° C, preferably not more than about 120 ° C. If the second surface layer includes or does not include such a polymer, conventional printing processes can also be used. The thermoplastic polymer or the thermoplastic polymers of the surface polymer layer may include a polymer comprising mer units derived from ethylene (eg, ethylene / alpha-olefin copolymers, polyethylene homopolymers, low density polyethylene (LDPE), polyethylene low linear density (LLDPE) very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE) ethylene / cyclic olefin copolymers, ionomers, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylate copolymers, as well as ethylene / (meth) acrylic acid copolymers); a polymer comprising mer units derived from propylene, (for example syndiotactic polypropylene and propylene / alpha-olefin copolymers); a polymer comprising mer units derived from styrene (such as for example polystyrene, styrene block copolymers, and styrene / alpha-olefin copolymers); copolyamides; copolyesters; polybutadiene; polyvinyl chloride); polybutene, and the like. The general idea with regard to the adhesion of pints on substrates has been that the surface tension of the substrate plays an essential function, but is that primary for determine how an ink adheres on a given substrate. However, research leading to the present invention has shown that the melting point (or other rheological property, such as, for example, softening point) of the polymer or of the polymers that make up the surface layer (i.e. which printing will be applied) of the substrate film plays a critical role. The use of polymers having melting points (or softening points) no greater than about 130 ° C, preferably no greater than about 120 ° C, allows the printing of a polymeric film without oxidant modification first of the film (as for example by treatment with flame or corona) or without chemical treatment of the film (as for example by applying a layer of preparation agent). Advantageously, the surface layer of the polymeric film also does not require any physical alteration (for example, polishing). In the packaging industry, printed polymer films are extensively used. Areas in which printed films (or packages made from them) are useful include the packaging of food items such as cut and uncut products, cuts of red meat, poultry, smoked and processed meats, cheeses, articles baked, etc .; the packaging of prepared foods and mixes of beverages; pet food packaging; presentation films clearly; packaging for refreshments; packaging resistant to theft; and similar. The following definitions apply throughout the present description unless clearly stated otherwise: "" polymer "refers to the product of a polymerization of one or more monomers and / or oligomers and includes homopolymers, copolymers, terpolymers, etc .; "copolymer" refers to a polymer formed by the polymerization of at least two different monomers and includes terpolymer; 'heterogeneous', in relation to polymers, means that they have a broad relative variation in molecular weight and compositional distributions, such as what can be obtained through the use of conventional multi-site catalysts (eg, Ziegler Natta) 'homogeneous', in relation to polymers, means polymers that have relatively narrow composition distributions and molecular weights, such as what can be obtained by the use of single-site catalysts (eg, ethylocenes or late transition metals); 'softening point' (or 'Vicat softening point'), in relation to a thermoplastic polymer, is the penetration temperature of this polymer, heated under loads, in accordance with the procedure in ASTM 1525, said process is incorporated herein by reference; "polyolefins" refers to a polymer of one or more alkenes which may be linear, branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted; (meth) acrylic acid "refers to an acrylic acid or methacrylic acid; 'methacrylate' refers to an ester of (meth) -chillic acid; 'ionomer' refers to a metal salt of a polymer that includes mer units derived from ethylene and acid (met) acrylic; "seal layer" refers to a film layer involved in sealing the film on itself (e.g., the inner layer on a fin-type seal and the outer layer on a seal of the splice type) or another layer (taking into account that only approximately 10 to 25 μm of a film are involved in the sealing of a film); "Binding layer" refers to any inner layer that has the primary purpose of adhering two layers to each other; "laminate" refers to a bond of two or more layers of film (e.g. with adhesives, or by application of heat and pressure); 'preparation agent' refers to a coating, usually polymeric, applied on the surface of a substrate to increase the adhesion of ink on the substrate; "chemically unprepared" in relation to films, refers to that no separate layer of preparation agent was applied to the film; "without oxidant preparation", in relation to the films, refers to that no alteration was made surface of the film through a process that oxidizes the surface of said film. DETAILED DESCRIPTION OF ILLUSTRATIVE MODALITIES The present invention includes the discovery that certain polymeric film substrates can be printed (e.g., by electrostatic devices) without the surface of said substrate having to first receive a preparation of some kind. Specifically, films having surface layers in which at least one polymer constituting said layer has a melting point not greater than about 130 ° C, preferably not greater than about 125 ° C, can be printed without the need for preliminary surface modification. Preferably, all polymers constituting the surface layer to be printed have melting points not higher than about 130 ° C, preferably not higher than about 125 ° C.

As mentioned above, the present invention relates directly to polymeric films. Although the present invention is not directly related to electrostatic printing (also known as electrophotographic), a brief review of the principles and methods involved in this technique are discussed here for convenience to the reader. In electrostatic printing, a photoconductive image formation plate (frequently in the form of a cylinder) with a uniform electrostatic charge is provided, typically by movement of the plate beyond a charge corona. This charged plate is exposed to an optical image. This image selectively discharges the image formation plate in order to form a latent electrostatic image. The image plate carrying the latent electrostatic image is exposed to a pigment composition (toner). The toner composition is normally fed (from a container stored separately by, for example, a compressed air mechanism) in the image plate very close to the portion that leads to the latent electrostatic image. The toner composition is deposited in the printing portions of the latent image in a pattern corresponding to the original image. Typically, the toner composition includes a non-polar liquid, a toner, thermoplastic polymer particles, and a Composite load direction. Some toner compositions further include a compound that stabilizes the electrical properties of the charge direction compound.

(An additional description of said toner compositions is provided below.) Unused toner may be recycled for later use. The pattern containing the toner is transferred from the image plate to a second plate, commonly known as a "blanket." The pattern is preferably transferred to the blanket since the toner is rejected from the image plate loaded very negatively toward the blanket. blanket less negatively charged When the image plate and the blanket are both in the form of a cylinder, the transfer can be achieved by rotating the image cylinder so that the pattern containing the toner comes into contact with the blanket cylinder The blanket is held at an elevated temperature, usually this temperature is within a range of about 120 ° C to about 135 ° C. The elevated temperature aids the melting of the toner, specifically, the thermoplastic polymer particles of the toner composition, which are insoluble in the non-polar liquid at room temperature and at slightly higher temperatures, they become soluble at temperatures above 50 ° C and consequently begin to melt when the composition of toners is heated by enzyme from its melting temperature. Usually, this is reached approximately 70 ° C. As said fusion proceeds (or coalescence), the toner in the pattern of the aforementioned image becomes trapped in the polymer film it forms. When a single color print is desired, the image can be transferred directly to the polymer film at this point. However, in multi-color printing, the polymer image remains in the blanket in a relatively tacky state while additional processing is observed. Specifically, the image plate again passes through the steps described above and a different color toner is applied. When the new latent image is formed, the second image (or subsequent image) is transferred from the image plate to the blanket in the same manner as described above. The second image (or subsequent image) corresponds to the first. The process is repeated until the transfer of all the colors on the blanket. Once all the individual color images are transferred onto the blanket, the overall image, ie, the polymer film formed in the blanket) is transferred to the polymeric film. When the blanket has the shape of a cylinder, this is achieved simply by rolling the cylinder in such a way that the polymer film image comes into contact with the cylinder. the polymeric film, which is near or in contact with the blanket cylinder. To help support the polymeric film during this process, a printing cylinder can be placed just below the blanket cylinder so that the two cylinders form a strangulation between which the polymeric film passes. The polymer film image is preferably transferred from the blanket to the polymeric film, perhaps due to the thermal bond between the image and the thermoplastic polymer. (if it is the case, said potential link can be increased by selecting a film where the thermoplastic polymer or the thermoplastic polymers of the surface layer is / are chemically compatible with the polymer of the film image or similar to said polymer). In this transfer process, the polymer film image is essentially laminated on the receiving surface of the polymeric film. The thickness of the polymer film image is of the order of one miera. After the transfer of the polymer film image onto the surface of the polymeric film, the image is rapidly cooled and dried. The polymer film is automatically advanced in such a way that another segment of the film can pass through the choke and is ready for another image transfer from the blanket cylinder.

Typically, the optical image to which the image plate is exposed is digitized. For example, images digitally stored in a recording medium (for example, the hard disk of a computer, a floppy disk, a magnetic tape, an optical disk, etc.) can be loaded into an image memory unit. That unit processes the information and activates a laser imager that creates the optical image to which the image plate is exposed. The process of recovering, processing, and transferring the optical image is typically controlled by means of a computer system, such as a Sun® workstation. The whole process that we just described can be carried out, for example, in an Omnius® color press. Additional details regarding the design and / or operation of this press (or electrostatic image formation in general) are provided, for example, in the following North American patents whose teachings are incorporated herein by reference: 5,558,970 (Landa et al.) 5,555,185 (Landa) 5,552,875 (Sagiv et al,) 5,532,805 (Landa ) 5,508,790 (Belinkov et al.) 5,426,491 (Landa, et al.) 5,335,054 (Landa et al.) 5,276,492 (Landa et al.) 5,155,001 (Landa et al.) 4,999,677 (Landa et al.) 4,984,025 (Landa et al. ) 4,974,027 (Landa et al.) The preferred compositions of toners for use in the present invention are generally classified as liquid toners, even when the use of dry toners is also contemplated. These toners include a non-polar liquid, thermoplastic polymer particles, a pigment, and a charge-targeting compound (dry toners have all of the above except the non-polar liquid component). Some may also include a compound that stabilizes the electrical properties of the charge targeting compound. The non-polar toner liquid generally has an electrical resistivity of at least 109 cm and a dielectric constant of less than about 3.0. The non-polar liquids commonly used include aliphatic hydrocarbons as well as light mineral oils. Of the aliphatic hydrocarbons, branched hydrocarbons are preferred, particularly the Isopar® series of isoparaffin hydrocarbons (Exxon Chemical Co., Houston, TX). The thermoplastic polymer particles of the toner are made from a polymer that includes mer units derived from one or more of the following: ethylene, propylene, vinyl acetate, (meth) acrylic acid, a (meth) alkyl acrylate (e.g., ethyl acrylate, methyl methacrylate, butyl methacrylate, etc.), acid terephthalic, an alkyl terephthalate (e.g., butyl terephthalate), and the like. Preferred polymers are polymers which include mer units derived from ethylene and vinyl acetate (for example, an ethylene / vinyl acetate copolymer). The toner pigment may be a dye (ie, a liquid pigment), or a particle (ie, a solid pigment). Representative examples of the foregoing include Monastral Blue B or G, Toluidine Red Y or B, Quindo Magenta, Monastral Green B or G, and the like, where representative examples of the latter include oxides such as metals such as Fe, Co, Ni, etc., ferrites of such metals as for example Zn, Cd, Ba, Mg, etc., alloys, carbon black and the like. In relation to the amount of polymer employed, the amount of pigment may be from about 10 to 35% by weight for colorants or from about 40 to 80% by weight for particles. The charge targeting compound of the toner can be a zwitterionic compound (for example, lecithin) or an ionic compound (for example the metal salt of a long-chain organic acid or an ester such as, for example, barium petronate). If desired, both types of charge targeting compounds (ie, zwitterionic and ionic) can be used together. Likewise, if desired, the charge addressing compound may used in combination with a polymer (e.g., polyvinyl pyrrolidone) which helps to stabilize the charge targeting compound or the charge targeting compounds. In general, the toner composition is prepared sequentially with polymer particle formation followed by the addition of the charge targeting compound. The first step includes (1) mixing at an elevated temperature (eg, 90 ° C) of the polymer or polymers of choice with a plasticizer which may be the same material subsequently used as a non-polar liquid or a different material, a pigment, and optionally a processing aid such as, for example, a wax until a homogeneous mixture is obtained; (2) cooling the mixture until it hardens and then cutting the mixture into bands; and (3) in the non-polar liquid, the wet milling of the bands in order to form particles with fibrous appendages. The vast majority of the particles containing fibers produced in this way preferably have diameters which are not greater than l-2μm. The non-polar polymer-liquid mixture is diluted to the desired concentration (generally about 1.5% solid) by the addition of more non-polar liquid. The charge-targeting compound is diluted in a volume separated from the non-polar liquid, and added progressively to a dilute paste of the polymer particles in the non-polar liquid until the desired conductivity is reached. This mixture can then be used as a toner composition. The preferred toners are those of the Electrolnk® series of toners (Indigo Ltd., Rehovot, Israel). Further details as to the composition, individual components, and / or manufacture of these toners are provided, for example, in the following North American patents, the teachings of which are incorporated herein by reference: 4,794,651 (Landa et al.) 4,842,974 (Landa et al. .) 5,047,306 (Almog) 5,047,307 (Landa et al.) 5,192,638 (Landa et al.) 5,208,130 (Almog et al.) 5,225,306 (Almog et al.) 5,264,313 (Landa et al.) 5,266,435 (Almog) 5,286,593 (Landa et al. .) 5,300,390 (Landa et al.) 5,346,796 (Almog) 5,554,476 (Landa et al.) 5,407,771 (Landa et al) Having described machines and processes useful for carrying out the present invention, we now focus on the receiving means of printing , that is, the movie. Films that include one or more thermoplastic polymer are used in the packaging industry for various purposes. Single-layer films are the simplest and, as the name implies, include only a single polymer layer.

More widely employed due to the adequacy properties they provide, are films that have two or more layers adhered or laminated together. Such multi-layer films can include layers with high permeability or low permeability to one or more gases (for example polyvinylidene chloride which is known to provide an oxygen barrier while polystyrene butadiene is known to have a good oxygen permeability). ), layers that include polymers with a high modulus of elasticity that provide strength, thermal seal layers, tie layers, and a wide variety of other layers that provide the film. of multiple layers one or several specialized properties. One or more layers of the film may include one or more additives such as antiblocking agents, anti-fog agents, pigments, antistatic agents, surfing agents, and the like. Regardless of whether the polymeric film is multi-layer or single-layer, said film may be supported on a sheet material as it passes through the printing press, (many multi-layer films are strong enough not to require such additional support. However, the present invention is not limited to films that possess said strength). Useful sheet materials include other polymeric films, paper, fabric, bands, pleats, and the like. The polymer film on which the printed image is applied may be adhered on the support sheet material. As mentioned above, the polymer films intended for printing usually have their surfaces treated in preparation for receiving the ink. Typical oxidizing treatments have included corona discharge treatment, flame treatment, and plasma f io treatment. The chemical treatment has involved the application of a different layer of preparation agent on the polymeric film before printing, (polishing of the surface of the film is also employed). Regardless of the type of treatment, it adds a costly additional step to the printing process and can have a negative effect on other film performance properties. Those skilled in the art have prepared the surface of films for electrostatic printing, and a whole industry has been developed around the manufacture and supply of ready-made films. However, the research that led to the present invention has shown that certain films can be electrostatically printed without undergoing a preparation step. The general idea has been that the adhesion of the ink (ie, toner) on the film surfaces depends essentially of the surface tension (i.e., modification of the film surface through corona discharge or flame as described above). Based on the research that led to the present invention, the rheology of the polymer or polymers in the surface layer of the film (ie, the layer receiving the printed image) seems to be at least equally important. In accordance with the present invention, an unprepared polymeric film can receive a polymeric film image (such as that produced by the electrostatic techniques described above) to the extent that the surface layer of the film includes one or more thermoplastic polymers that they have a melting point no greater than about 130 ° C, preferably not greater than about 125 ° C. When the polymeric film is a multilayer film, the surface layer is the outer layer that finally receives the printed image; if both outer layers are to be printed, both are considered as surface layers for the purposes of the present invention. Since the vast majority of polymers do not have a precise melting point (as is the case with crystalline solids), certain protocols are accepted by those skilled in the art. For example, a common way of measuring certain The properties of a polymer is through the use of a differential scanning calorimeter (DSC). When analyzed in a DSC, many polymers have several peaks that correspond to different melting points or endothermic events. For convenience and clarity, the melting point of such a polymer is considered to be the center of the highest endotherm. Thermoplastic polymers having melting points not exceeding about 130 ° C, preferably not exceeding about 125 ° C, include many polymers containing mer units derived from ethylene, propylene and / or styrene. Those containing mer units of ethylene derivatives are particularly preferred. Representative examples of these polymers include mer units derived from ethylene including, but not limited to, ethylene / alpha-olefin polymers, polyethylene homopolymer, LDPE, LLDPE, VLDPE, ULDPE, ethylene / cyclic olefin copolymers, ionomers, ethylene copolymers. / vinyl acetate, ethylene / (meth) acrylate copolymers, and ethylene / methacrylic acid copolymers. Representative examples of polymers containing mer units derived from propylene include, but are not limited to, syndiotactic polypropylene as well as propylene / alpha-olefin copolymers. Representative examples of polymers containing mer units Derivatives of styrene include polystyrene (an amorphous polymer without melting point), styrene block copolymers and styrene / alpha-olefin copolymers. Other potentially useful polymers include copolyamides, certain copolyesters, polybutadiene, polyvinyl chloride, and polybutene. One hypothesis proposed to explain the results observed in the following examples is that the polymer in the surface layer of the polymeric film deforms slightly or flows when it comes into contact with the press blanket described above, which is typically maintained at a temperature of about 120 ° C to about 135 ° C. When the polymer film image is transferred from the blanket to the polymeric film, the thermally softened surface layer readily accepts the "lamination" of the polymer film image. Based on this hypothesis, one skilled in the art can observe that the The melting point of the polymer may not always be the critical factor, for example, especially in terms of amorphous polymers, the glass transition temperature is potentially the critical factor.Alternatively, the softening point of the polymer is potentially a critical factor. , the polymers with softening point below about 130 ° C, preferably with softening points not greater than about 125 ° C, they are also potentially useful in combination with the present invention. In cases of polymer blends, the softening point can potentially be a more convenient guide than the melting point. However, experience has shown that, for most polymeric films, the softening point of the polymer or polymers in the surface layer is a reliable indicator of whether it can be employed in accordance with the present invention. Based on the foregoing, a person with some experience in the field can see that the establishment of a lower limit at the melting point of potentially useful polymers is problematic, if not counterproductive. For example, if the operating temperature of the blanket is reduced below its normal range (i.e., approximately 120 ° C-135 ° C), films having a surface layer that includes a polymer with a very low melting point. - films that may otherwise become excessively sticky during the printing process - may become useful. As previously stated, while not wishing to be limited by any particular theory, it is believed that the thermal properties play a significant role in determining the polymers that can be employed in combination with the present invention and the polymers that can not be used in combination with the present invention. . In addition to the point of melting and the glass transition temperature, the molecular weight of the polymer influences the rheology. For example, a polymer with a low melting point that has a high molecular weight or that has been cross-linked may be useful in high blanket temperature environments. However, polymers having melting points of at least about 65 ° C, preferably at least about 75 ° C, more preferably at least about 85 ° C, preferably even greater than at least about 90 ° C, are particularly considered tools. In addition to the discovery that certain polymeric films can be included without any advance preparation, the work carried out by the present invention has surprisingly shown that such films also exhibit a tendency to retain images of this type when heat treated. As mentioned above, many polymeric films used in the packaging industry are heat-shrunk (such as by passing through hot water or a steam tunnel) before their final use. The delamination of the image from the film does not occur easily when the procedure described above is applied. The fact that unprepared films can not only be printed, but also preserve the printed image upon application of a heat treatment, is an unexpected and significant advantage of the present invention.

Once printed, the polymeric film can be further processed. For example, one or more protective layers (e.g., an abuse protection layer) may be laminated (e.g., thermally or adhesively) over the printed polymeric film in order to create a trapped printed product. Alternatively, one or more polymeric layers that provide useful properties for overall construction (eg, an oxygen barrier layer) can be laminated onto the printed polymeric film. Also, if desired, the printed polymer film can be converted (in line or offline) into a package by creating one or more closures. When the printed film is in the form of a tube, only a bottom closure is required or only the application of a bottom closure is required before creating a bag in which a given product can be placed. When the printed film is not in the form of a tube, several closures can be applied in order to form packages having various geometries, (for example, stamps can be created by, for example, a typical heat sealing equipment while the application of a staple or an adhesive can provide alternative means of closure). The following examples illustrate additional aspects of this invention. The particular materials and amounts, as well as other conditions and details, discussed in these examples are not contemplated as limiting this invention. EXAMPLES Several polymeric films were printed on an indigo press E-Print® 1000 (a color press for paper printing, manufactured by Indigo Ltd.) in accordance with the specifications provided by an Omnius® color press (a press color for film printing) in order to simulate the printing process that occurs in the latter. The results for these films appear in examples 1-4. Then, several unprepared polymer films were printed in a similar manner, this time in an Omnius® color press, and the results regarding these films appear in examples 5-14. The performance of the two multi-layer tube forming materials was measured before and after post-printing heat treatment, and the results are given in Examples 15-18. Examples 1-4 Sheets of four films with various surface tensions were used in an E-Print® 1000 press in a manner that simulates the conditions experienced in a press Omnius ® color. Untreated films were examined, as well as films treated with a Topaz ® preparation treatment.

(Indigo, Ltd). Both the ability of the films to receive a printed image and the adherence of the printed image to the films were determined. This last property was determined by the application and then the removal of a band of pressure sensitive adhesive tape (PSA) from the printed image and determining if the image remained in the film. The results appear below as "good", "limited", or "failure." In the table presented below, the following polymer films were tested with and without preparation agent: 1. EG® polyethylene terephthalate (Amertiape, Inc., North Bergen, NJ) 2. Capran ® Saran Coated Nylon (Allied Signal, Inc., Morristown, NJ) 3. A Cryovac® Multi-Layer Film with a Polypropylene Surface Layer (WR Grace &Co.; Duncan, SC) 4. A Cryovac® multi-layer film having an outer layer of homogeneous ethylene / octene copolymer (W.R. Grace &Co.) Table 1 Sample tension melting point Surface No. of the surface layer (dynes) (° C) 1 54 265 2 38 225 3 < 32 161 4 < 32 100 Muee ¡tra No treatment of prepared No. Printing Adherence 1 limited failure 2 limited failure 3 failure - 4 good good Show (Zon treatment of preparation No. Printing Adherence 1 good good 2 good good 3 limited fault 4 good good As you can observe from the data in table 1, the only film that did not receive preparation treatment and that passed the adhesion test was example 4. Likewise, these data do not clearly establish a correlation between printing capacity and surface tension. Example 5-14 Ten untreated films (ie, not treated with a preparation agent) were used in a one-color Omnius® color press to determine their printability. The films were 5. Escorene ® LD-318.92, an ethylene / vinyl acetate copolymer (Exxon) 6. XU59220.01, a homogeneous ethylene-octene copolymer (Dow) 7. PE-1042CS5, a low density polyethylene ( Rexene Products, Dallas, TX) 8. Dowlex® 2045.03, a linear low density polyethylene (Dow) 9. Escorene® PD-9302, a propylene / ethylene copolymer (Exxon) 10. Escorene® PD-3345, polypropylene (Exxon) 11. ffinity® PL 1140, a homogeneous polyethylene (Dow) 12.Affinity® PL 1850, a homogeneous polyethylene (Dow) 13. Escorene® LD 409.09, a low density polyethylene (Exxon) 14.Surlyn® 1705, an ionomer (DuPont de Nemours; Wilmington, DE) The ability of the films to receive a printed image was determined and the results appear below as 'approved' or 'failed'. For the films that could be printed, their ability to maintain adhesion to the printed image (using a PSA tape test described in Examples 1-4) was also determined and the results are reported below as' good '' acceptable " , or 'limited. "Table 2 Sample number Melting point (° C) 5 98 6 100 7 112 8 123 9 139 10 161 11 102 12 98 13 112 14 98 Sample number Printing capacity Adhesion 5 approved limited 6 approved acceptable 7 approved limited 8 approved limited 9 failed 10 failed 11 approved good 12 approved good 13 approved limited 14 approved good As can be seen from the data in table 2, polymer films with melting points lower than approximately 130 ° C could be printed, even in the absence of a chemical step or oxidant preparation. Films with melting points above 130 ° C could not be printed successfully. No clear trend can be established in terms of adherence, based on these data. Examples 15-18 A Cryovac® multi-layer tube forming material having a surface layer of homogeneous ethylene / octene copolymer with a melting point of 94 ° C (WR Grace &Co) was printed and then tested to determine ink adhesion (using the PSA ribbon transfer test described in examples 1-4) both before (example 15) and after (example 16) having passed through a hot water tunnel at a temperature of 99 ° C (210 ° F) at approximately 1.07 m / min (35 feet / minutes). A Cryovac® multi-layer tube forming material with a surface layer including a blend of ethylene / vinyl acetate copolymer and LLDPE (W.R. Grace &Co.) was treated and tested to determine the adhesion of the ink both before (example 17) and after (example 18) having passed through the hot water tunnel in the manner established in the previous paragraph. The results are shown below in Table 3, with the adherence of the qualified image on a scale of 'limited', 'acceptable', 'good', and 'excellent'. Table 3 Sample No. Adhesion 15 Good 16 Excellent 17 Good 18 Excellent The results in Table 3 show that the adhesion of the polymer film images on the polymeric films can surprisingly improve after heat treatment of a printed film, as it could happen during the thermal shrinkage of the film. Various modifications and alterations that are not outside the scope and spirit of the present invention will be readily apparent to those skilled in the art. This invention is not limited to the illustrative embodiments presented herein.

Claims (17)

1. CLAIMS 1. A flexible, printed thermoplastic packaging material comprising: a) a thermoplastic packaging film comprising a surface polymer layer, said surface polymer layer comprising a thermoplastic polymer having at least one of a melting point and a point of Vicat softening no greater than about 130 ° C; And b) in said surface polymer layer, a printed image derived from a toner, c) said surface polymer layer is not prepared chemically or by oxidation.
2. 2. The printed flexible thermoplastic packaging material of claim 1, wherein said thermoplastic polymer has at least one of a melting point and Vicat softening point of no more than about 125 ° C.
3. 3. The printed flexible thermoplastic packaging material of any of claims 1 and 2, wherein said thermoplastic polymer comprises mer units derived from ethylene.
4. 4. The printed flexible thermoplastic packaging material of any of claims 1 to 3, wherein said thermoplastic packaging film further comprises a or several polymeric layers laminated on said surface polymer layer.
5. 5. The printed flexible thermoplastic packaging material of claim 1, wherein said thermoplastic packing film is supported on a sheet material.
6. 6. The printed flexible thermoplastic packaging material of any of claims 1 to 5, wherein said substrate film is sealed in order to form a package.
7. A printed flexible thermoplastic packaging material consisting essentially of: a) a thermoplastic packing film comprising a surface polymer layer, said surface polymer layer comprising a thermoplastic polymer having at least one of a melting point and a point of Vicat softening of no more than about 130 ° C; and b) in said surface polymer layer, a printed image in the form of a polymeric film.
8. The printed flexible thermoplastic packaging material of claim 7, wherein said thermoplastic polymer has at least one of a melting point and a Vicat softening point of not more than about 125 ° C.
9. 9. The printed flexible thermoplastic packing material of any of claims 7 and 8 wherein said thermoplastic polymer comprises mer units derived from ethylene.
10. The printed flexible thermoplastic packaging material of any of claims 7 to 9 wherein said thermoplastic packaging film further comprises one or more polymer layers laminates on said surface polymer layer.
11. The printed flexible thermoplastic packaging material of claim 7, wherein said thermoplastic packaging film is supported on a sheet material.
12. The printed flexible thermoplastic packaging material of any of claims 7 to 11 wherein said thermoplastic packing film is sealed in order to form a package.
13. A process for making a printed flexible thermoplastic packaging material comprising the step of transferring a polymeric film image from a heated plate to a surface of a thermoplastic packaging film, said thermoplastic packaging film comprising a surface polymer layer comprising a thermoplastic polymer having at least one of a melting point and Vicat softening point of not more than about 130 ° C said layer polymeric surface is not chemically prepared or oxidizing.
14. The process of claim 13, wherein said thermoplastic polymer has at least a melting point and a Vicat softening point of no more than about 125 ° C.
15. 15. The process of any of claims 13 and 14, wherein said polymer film image comprises a thermoplastic polymer that traps one or more types of pigment. The process of claim 15, wherein said thermoplastic polymer that traps one or more types of pigment particles is derived from a toner comprising: a) a non-polar liquid; b) a thermoplastic polymer particle having a plurality of integral fibers extending therefrom, said fibers can form mat with similar fibers or other particles of this type; c) a charge director, and d) optionally a compound to stabilize the electrical properties of said charge director. The process of claim 16, wherein said thermoplastic polymer particle comprises a polymer comprising mer units derived from ethylene and, optionally, further comprises mer units derived from vinyl acetate. The process of any of claims 13 to 17, wherein said thermoplastic polymer is a homogeneous polyethylene, a low density polyethylene, a linear low density polyethylene, the metal salt of a polymer comprising mer units derived from ethylene and acid (meth) acrylic, or an ethylene / vinyl acetate copolymer. The process of any of claims 13 to 18, wherein said polymer film image is created by means of an electrostatic process.