Patent Application
20150183253
Films may be used for printing materials, such as signs and banners. Inkjet printers may be used to print upon such materials using solvent, eco-solvent, mild solvent, latex, and/or ultraviolet (“UV”) inks. The present invention includes films for printing and methods of their manufacture.
In one embodiment, the invention includes a printing layer of a film comprising a blend of at least one high absorption capacity material and at least one low absorption capacity material.
In another embodiment, a film for printing. The film includes a print layer, a core layer, and an adhesive layer, and the core layer is between the print layer and the adhesive layer. In addition, the printing layer includes a blend of at least one high absorption capacity material and at least one low absorption capacity material.
The following description illustrates one or more embodiments of the invention and serves to explain the principles and exemplary embodiment of the invention.
Reference will now be made in detail to exemplary embodiments of the present invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation of the invention and not by limitation of the invention. It will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. In addition, the use of reference characters with the same two ending digits as other reference characters to indicate structure in the present specification and drawings, without a specific discussion of such structure, is intended to represent the same or analogous structure in different embodiments. Unless otherwise indicated herein, all percentages used for a component refer to the percentage by weight.
In some embodiments, the present invention includes films and other materials for printing or marking with ink. In some embodiments, materials of the present invention may include a print layer (also interchangeably referenced as a printing layer herein), an optional tie layer, a core layer, and an adhesive layer. In other embodiments, such materials may exclude certain layers. In some embodiments, the total film thickness may be from about 2.5 mils to about 3.2 mils.
Print layers of the present invention may include a blend of at least one high absorption capacity material, such as poly(methyl methacrylate) (“PMMA”), polystyrene, polyethylene terephthalate glycol-modified (PETG), and styrene-based copolymers, impact modified polystyrene, styrene acrylic copolymer, styrene-olefin copolymer, styrene-acrylic-olefin copolymer, acrylonitrile butadinene styrene polymer, styrene acrylonitrile polymer, and copolyester polymer, and at least one low absorption capacity material, such as an olefin polymer, including random copolymers and/or block copolymers. By way of example, suitable olefin copolymers may include, without limitation, ethylene acrylate coplomers, such as ethylene acrylic acid (EAA), ethylene methyl acrylate (EMA), and ethylene butyl acrylate (EBA), ethylene vinyl acetate (EVA), and/or ethylene acrylic ester terpolymer. As used herein, unless the context dictates otherwise, the term copolymers may also reference terpolymers. In one particular embodiment of the present invention, the print layer includes PMMA and an olefin polymer, including random copolymers and/or block copolymers.
Any suitable formulation may be used. In some embodiments, at least 10% low absorption capacity material may be present in the formulation. In other embodiments, at least 17% low absorption capacity material may be present in the formulation. In addition, in some embodiments at least 20% high absorption capacity material may be present in the formulation. In some embodiments, about 20% to about 83% high absorption capacity material may be present. In still some embodiments, less than 83% high absorption capacity material may be present. Notably, neither PMMA nor olefin copolymers were observed during testing to independently provide suitable materials for ink printing.
A print layer may have any thickness suitable for a particular embodiment. In some embodiments, a print layer may have a thickness greater than about 0.38 mils. In some embodiments, a print layer may have a thickness in the range of about 0.6 mils to about 1.0 mils, including each intermittent value therein. In other embodiments, a print layer may have a thickness in the range of about 0.6 mils to about 3.0 mils. In still other embodiments, a print layer may have thickness up to about 6.0 mils. Any remaining layers of the film may be of any suitable thickness for a particular embodiment.
In some embodiments, the print layer may include multiple adjacent layers. For example, in some embodiments, a print layer may include two adjacent layers, wherein each layer includes the same blend of at least one high absorption capacity material and at least one low absorption capacity material. In addition, in some embodiments at least one layer of the two adjacent layers further includes absorbing particles, such as silica, alumina silicate, nano clay, calcium carbonate, zinc oxide, titanium dioxide, and/or other absorbing particles or other suitable absorbing particles or resins. In some embodiments, the particle sizes may be in the range of about 0.1 to about 10 microns, including each intermittent value therein. In addition, multiple particle sizes may be present in some embodiments. For example, various particle sizes may be present in a single print layer in some embodiments. In addition, embodiments having multiple print layers may each have either the same or distinct particle sizes.
By way of example,
In some other embodiments, additional layers having either the same or different compositions may be included in a multilayer print layer. In still other embodiments, a film of the present invention may be a single layer consisting of only the printing layer. In such embodiments, an adhesive, such as a pressure sensitive adhesive, may be applied directly upon that layer. Each layer of a multilayer print layer may be of the same thickness or may have varying thicknesses.
In some embodiments of the present invention, a multilayer print layer may have a morphological gradient. In such embodiments, a print layer may include a first layer in which PMMA is the major component of the blend in the layer and a second layer having the same blend components as the first layer but in which PMMA is the minor component. This may create different absorption capacity between the two adjacent layers forming the image receptive layer.
The print layer may be formulated to include an ultraviolet stabilizer package in some embodiments, particularly when the materials are intended to be used for outdoor display. In some embodiments, a suitable ultraviolet stabilizer may include the ultraviolet light stabilizer Ampacet UV 10561, available from Ampacet Corporation. By way of further example, the ultraviolet stabilizer package may include free radical scavengers and an ultraviolet light stabilizer. Free radical scavengers, such as hindered amine light stabilizer (HALS), may be present, alone or in addition to UV light stabilizers, in an amount of about 0.05 to about two weight percent per layer, and the UV light stabilizers, such as benzophenone, can be present in amounts ranging from 0.1 to about 5 weight percent per layer. Such ultraviolet stabilizer packages may be included in the print layer. In multilayer print layers, such ultraviolet packages may be included in some or all of the layers of the print layer.
Similarly, print layers of the present invention may also or alternatively include heat stabilizers. Heat stabilizers may include Ferro 1237, Ferro 1720, and Synpron 1163, all available from Ferro Corporation Polymer Additives Division, and Mark V 1923, available from Witco Corp. By way of example, heat stabilizers may be present in an amount from about 0.2 to about 0.15 percent by total weight of a print layer, including each intermittent value therein. In multilayer print layers, such heat stabilizers may be included in some or all of the layers of the print layer.
In some embodiments, a print layer may also include a compatibilizer. By way of example, a suitable compatibilizer may include a block copolymer. In some particular embodiments, styrene-ethylene-butylene-styrene may be included as a compatibilizer in a print layer, such as in a print layer having a blend of PMMA and ethylene copolymer. A compatibilizer also may improve the gloss of the print layer in some embodiments. In multilayer print layers, such compatibilizers may be included in some or all of the layers of the print layer.
Some embodiments of print layers of the present invention may also include one or more process aids, such as Ampacet 10919, which is available from Ampacet Corporation. In addition, some print layer embodiments may include a flame retardant compound. By way of example, some embodiments may include FR-2005 (which is a flame retardant and ultraviolet stabilizer and available from Polyfil Corporation). In other embodiments, the print layer may also include one or more pigments, antiblock agents, and/or matting agents.
As indicated, materials of the present invention may also include a tie layer. When present, a tie layer may be located between a print layer and a core layer of the film. A tie layer may be comprised of any suitable material for a particular embodiment. In some embodiments, a tie layer may improve the interlayer adhesion between the print layer and the core layer. In some embodiments, a tie layer may be included if the blend of the print layer includes more than 50% by weight of PMMA.
Suitable tie layer resins may include, by way of example, ethylene vinyl acetate, such as those sold by Celanese under the Ateva trade name, Elvax resins sold by ExxonMobil, Bynel resins sold by Dupont Corporation, and Evatane resins sold by Arkema. In addition, other resins suitable for a tie layer may include random terpolymer of ethylene, vinyl acetate and maleic anhydride, such as OREVAC-T9304 sold by Arkema, and materials of similar structure.
Embodiments of the present invention may also include a core layer. Such core layers may be comprised of any material to provide suitable mechanical strength and a desired opacity to the film. In some embodiments, any suitable olefin polymer or combination of olefin polymers may be included in the core layer. By way of example, a core layer may be comprised of any suitable olefin polymer. In some embodiments, a core layer may comprise polyethylene, such as low density polyethylene and/or linear low density polyethylene may be present in the core layer. In other embodiments medium density and/or high density polyethylene may be present in the core layer. In addition, the core layer may optionally include color pigments.
In some embodiments, the present invention may also include an adhesive layer. The adhesive layer may include ethylene vinyl acetate. In some embodiments, the adhesive layer may also include polyethylene, such as low density polyethylene and/or linear low density polyethylene. An adhesive layer may also have one or more ultraviolet stabilizers, process aids, and/or flame retardants. A suitable adhesive may be applied to the adhesive layer, optionally with a release liner, in some embodiments.
In some embodiments, as indicated above, films of the present invention may also include a pressure sensitive adhesive layer and a releasable liner. The adhesive may be applied upon any suitable layer of the film, such as, for example, an adhesive layer. In single layer embodiments, the adhesive may be applied directly upon that single layer. The release liner may be position adjacent the adhesive such that the adhesive is disposed between the release liner and the film.
Films of the present invention may be prepared using any suitable process. By way of example, films of the present invention may be prepared using cast film processes, blown film processes, and extrusion and coextrusion processes.
Films of the present invention may be configured to provide suitable qualities for printing, such as receiving ink from a printer, including ink jet printers. In such embodiments, the ink absorption capacity and the absorption speed of the film, and specifically the print layer of a film, provide a suitable printing surface for good quality printing. In such embodiments, films of the present invention may dry suitably such that the ink does not remain wet for an undesirable period of time, and such films may also dry without significant cracking in the ink. The following examples provide additional details of exemplary embodiments of films of the present invention.
In the following examples, films having a total thickness of 2.5 to 3.2 mils were prepared. In addition, the films were tested using a core layer comprised of 57% low density polyethylene (such as available from Flint Hills Resources (“FHR”)) and 43% TiO2 (such as available from Ampacet Corporation) and an adhesive layer of 60% low density polyethylene, 30% Ampacet 111712, and 10% ethylene vinyl acetate. For all examples, the gloss was measured using a BYK Gardner gloss meter, and the gloss reported is the average of the gloss measured in the machine direction (MD) and the cross direction (CD). The reference table below provides an index to materials referenced in the following examples:
Multilayer films were produced using a conventional 4-layer cast film co-extrusion process. Each of the four extruders A, B, C, D supplied a melt formulation to a feedblock where the melts were combined to form a single molten stream consisting of four different layers. To achieve a print layer thickness of about 0.6 to about 1.0 mils, both extruders A and B were fed with the print layer formulation as indicated in the following table. Extruders C was fed with molten layer of linear low density polyethylene for forming the core layer of the film and linear low density polyethylene and ethylene vinyl acetate for forming the adhesive layer were fed through extruder D. The extruder zone temperatures were Z1=390° F., Z2=420° F., and Z3=420° F. and the die temperature was 420° F. The extrudate from the die was cooled on a matte chill roll having a surface roughness average (Ra) of 40. The print layer contacted the chill roll during the cooling process with a chill roll temperature set at 90° F. and an airknife speed of 60 Hz. Table I shows the formulations used in the different extruders. In some variations in Example I, no tie layer was included in the film.
The films were tested for printability using eco-sol and latex inkjet systems. In the particular examples, printing of a multicolor test image was performed using a Roland Soljet Pro II XC-540 printer (available from Roland Company) equipped with eco-sol Max inkjet inks, and an HP Designjet L25500 printer (available from HP) equipped with HP 789 latex inks. In addition, print qualities were observed and recorded as reported in Table I below. As used below and in subsequent charts, “NM” designates that the value was not measured.
Thus, it was observed that a suitable blend of high absorption material and low absorption material in a print layer resulted in suitable and improved print quality. Although ink cracking had been observed in films having over 83% PMMA without olefin copolymer in the print layer, such cracking was not shown for blends with 83% or less PMMA when blended with at least 10% by weight of olefin copolymer. In the Eco-sol inkjet printing, crystal polystyrene, impact modified styrene, and acrylic styrene copolymer themselves have high ink absorption and may be partially dissolved by an ink solvent at high ink loading, which may result in light color density and appearance of micro ink drop dents on a surface after printing. However, after blending such materials in the print layer with low ink absorption material(s) such as EVA or SEBS, it was observed in testing that the print quality was improved.
In addition, as shown in
A multilayer film was prepared similar to Example I except the print layer included two layers comprised a blend of Plexiglas HFI-7 with different polymers at different ratios in the adjacent layers such that the absorption capacities of the two adjacent layers were different. The two adjacent layers collectively form the print layer of the film, and the print layer (including all layers in the print layer) was about 0.6 to about 1 mil thick. Table II shows the formulations used in the two adjacent layers. The core layer and the adhesive layers were the same as in Example I. The films of this example were then tested in the same manner described above for Example I, and the results are recorded below in Table II.
By using different blend ratios in adjacent layers to form the print layer, a morphological gradient is created in the print layer resulting in a print layer with varying absorption capacities across the print layer thickness.
Multilayer films similar to Example I were created by co-extruding the layers as described in Example I but using a PMMA copolymer. The core layer and the adhesive layers were the same as in Example I. The copolymers of PMMA used in the blends are provided in Table III below. Films indicated with an asterisk (*) were nipped to a matte roll during the extrusion process. The films of this example were then tested in the same manner described above for Example I, and the results are recorded below in Table III.
As shown in Table III, the addition of ethylene acrylic copolymer content in the blend of PMMA or copolymer of PMMA eliminates the cracks that are observed in the image when printed with eco-sol ink.
Example V was a multilayer film produced similar to the Example I except that the print layer included a blend of PMMA and an ethylene-based copolymer and a block copolymer to improve the phase compatibility and, consequently, the gloss of the print surface. The components for the print layer were first compounded using a twin screw extruder equipped with a pelletizer. The compounded pellets were then fed into the single screw extruder as described in Example I. Printability was tested with Roland eco-sol system described above, which had been established in previous testing as the most difficult solvent to print, and HP Patex L25500 printers. The copolymers and layers are listed in Table IV. The surface gloss of the films were measured using Gardner Glossmeter and are reported below, wherein the data represents the average of the gloss measured in MD and CD. The following materials are also reference in this example:
Example V was a multilayer film formed similar to Example III above but using PMMA from three different sources. With reference to Table V below, the Parapet TNA was sourced from Kuraray America and the nanostrength polymers were obtained from Arkema. The print layer formulation was pre-compounded using a twin screw extruder as described in Example IV. The preformed pellet was fed into a screw extruder and co-extruded into a multilayer film. The resulting multilayer films were evaluated using the same Roland eco solvent printer discussed above and a Mimaki JV33 (mild solvent) inkjet printer available form Mimaki, USA.
As demonstrated by the results above, the addition of block copolymer to the blend as a compatibilizer may improve the print quality of the image as well as the structural compatibility with ethylene methacrylate. In some embodiments, it was also observed that Nanostrength E21, which has polybutadiene midblock, shows better gloss and print characteristics than Nanostrength M52, which has poly(butyl acrylate) midblock.
In this example, multilayer films were formed similar to Example III. The print layer formulation was pre-compounded into a pellet before being fed into a single screw extruder. In addition, extrudate from the die was cooled onto a chrome roll and nipped with a rubber roll to improve the surface gloss of the incompatible blend layer. The formulations are listed in Table VI below.
The films were tested for printability and gloss by printing the image using a variety of inkjet systems. The gloss of the film was tested before and after printing the image. In addition to the previously-described printers, a Mimaki UJF 3042 (UV inkjet) printer available from Mimaki USA was also used in this testing. The testing results are provided in Table VI below.
From the results above, it was observed that the use of a chrome casting roll resulted in improved gloss of the film. For reference, it was observed that the gloss of the films tested above were generally comparable to the gloss of the TrueImpact (“TMP”) 7000 series product sold commercially by Avery Dennison Corporation, which is a gloss in the range of about 50 to about 70.
Scanning electron microscope images were also obtained for some of the films in Table IV. For example,
In addition, the films from Table VI were tested for printability on each printer described in Table Vi. Upon review, the print image from each printer was of good and suitable quality. In addition, no image showed any print defects.
The print images obtained from the Roland XC-540 (eco-sol) printer, HP L25500 (latex) printer, and Mimaki JV33 (mild solvent) printers were further analyzed using a QEA PIAS-II meter to determine the dot size and ink bleeding characteristics of the print quality obtained from the multilayer films of the present invention against TrueImpact (“TMP”) 7000 (sustainable print media sold by Avery Dennison Corporation) and the standard vinyl products under the trade name MP12105 and MPI 2900 also sold by Avery Dennison Corporation. The following results were recorded:
As shown above, both the dot sizes and the bleed characteristics of the multilayer films of the present invention are similar in quality to known vinyl products in the market. In addition, the print quality between the multilayer films of the present invention are similar to the accepted print quality of the known vinyl media.
In this example, a TrueImpact overlaminate film sold by AveryDennison Corporation as TOL 7000 series was laminated with the 58072 adhesive, available from Avery Dennison, to the print surface of some of the samples of Example VI. The 60-degree gloss of the TOL 7000 series was measured to be between 80-90. As provided in the results below, it was observed that the gloss of the film with the laminate may be significantly increased with a laminate relative to the original film.
Multilayer films were formed similar to Example III. The print layer formulation of 60% Lotryl 29MA03 and 40% Plexiglas HFI-7 was pre-compounded using a twin screw extruder into a pellet before being fed into a single screw extruder. The extruder RPM values were changed to create three different samples with different print layer thicknesses. The formulations, thicknesses (determined from scanning electron microscope measurements), and results were as follows:
These results suggest that a minimum thickness of the print layer should be greater than 0.38 mils to achieve drying of the image.
Embodiments of the present invention may be used for any suitable purpose. In some embodiments, films of the present invention may be printed to create signs, posters, banners, and other printed materials. Films of the present invention may be printed upon using a selection of one or more inks from a variety of inks. In specific embodiments, films of the present invention may be suitable for inkjet printing. Generally in inkjet printing, ink is deposited onto the film surface as dots, which then spread and join together to provide, ideally, a substantially uniform appearance. As demonstrated by the examples above, films of the present invention do not, in some embodiments, require a specific type of ink but may be suitably printed with one or more of a variety of suitable inks for inkjet printing.
These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and it is not intended to limit the invention as further described in such appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the exemplary description of the versions contained herein.
The present application claims the benefit of U.S. Provisional Application No. 61/921,641 filed Dec. 30, 2013, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61921641 | Dec 2013 | US |
