Semi-crystalline, clear rigid medical packaging with engineered spherulite growth limitations via multi-layered boundaries

Abstract

An article and process for forming the article, wherein the process limits the spherulite size in the semi-crystalline layers such that articles or packages made from the film remain thermoformable yet can withstand steam sterilization without a significant degree of shrinkage, warpage, or generation of visual haze. The process includes producing a multilayered sheet of at least two thermoplastic materials wherein at least one of the thermoplastic materials forms semi-crystalline layers.

Description

SEMI-CRYSTALLINE, CLEAR RIGID MEDICAL PACKAGING WITH ENGINEERED SPHERULITE GROWTH LIMITATIONS VIA MULTI-LAYERED BOUNDARIESCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application 63 / 470,348 filed June 1, 2023, and U.S. Provisional Application 63 / 538,691 filed September 15, 2023, both of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION

[0002] Today, clear, rigid medical packaging is normally made from non-oriented PETG copolyester, or alternatively, from the less expensive, non-oriented polyesters PET / APET. Three- dimensional packages made from either of these materials can be sterilized by ethylene oxide, gamma radiation, or other processes, but neither packaging material can be properly steam sterilized without detrimentally altering the package, due to the materials’ relatively low heat distortion temperature. A second issue with both of these traditional materials is that they also undergo warpage and a significant amount of physical aging, leading to embrittlement and the potential for a loss in package sterility when the (ethylene oxide, gamma, etc.) sterilization protocol is severe or when multiple sterilization cycles are necessary.

[0003] The present disclosure involves starting with a crystalline or semi-crystalline thermoplastic polymer and forming this resin into a clear film or sheet through traditional processing such as extrusion. The clear film or sheet is then partially stretched or oriented in a process such as occurs on a tenter frame. This partially stretched film or sheet is then heated and thermoformed into a three-dimensional article. The three-dimensional article, optionallypackaging, optionally rigid medical packaging, is then heated while on the mold to heat set or remove internal part stresses (thermoplastic “memory”) from the three-dimensional article so that it is dimensionally stable up to the heat set temperature. The three-dimensional article is then closed around a device, optionally a medical device, sealed and steam sterilized for sanitized use.

[0004] For example, in some embodiments, PET or APET film or sheet can be partially stretched or oriented, to enable these packages to be autoclave steam sterilizable, on a device that will outwardly stretch, thermoform, and then retain the three-dimensional article on the mold for heat setting to be accomplished. This solitary device is capable of transforming “off the shelf’ PET or APET sheet or roll stock into three-dimensional articles capable of autoclave steam sterilization.

[0005] For example, some embodiments of this disclosure involve a process performing the following functions or a solitary forming device capable of performing the following functions: precisely feeding roll stock film or individually cut sheet; clamping said film or sheet along the perimeter with mobile clamps that are capable of retracting to stretch the film or sheet in the outward, planar direction with heating between the clamps; a heating oven to raise the sheet temperature well above its glass transition temperature; a movable mold platen with temperature control capability; vacuum capability optionally with plug assist for precision part definition; and, forced air convection cooling system.SUMMARY OF THE INVENTION

[0006] The present disclosure identifies the chemical architecture (e.g., polymeric morphology), processing techniques, and operational ranges needed to induce a certain degree of orientation into the semi-crystalline resin used in these articles while maintaining the ability of the resin in sheet form to be thermoformed into three-dimensional articles.

[0007] Coupled with the subsequent heat setting step, three-dimensional articles can be subsequently steam sterilized in an autoclave without a significant degree of haze generation or package warpage. Articles or packages made from the processes described in the current disclosure have the additional advantage of also being tougher, among other physical property improvements, than packages made from amorphous PETG, PET, or APET and utilize chemistries that are traditionally less expensive than PETG.

[0008] The present disclosure involves extruding a crystalline or semi-crystalline thermoplastic polymer in a first layer and simultaneously co-extruding a second, rheologically- compatible thermoplastic polymer in a second layer. This melt stream is subjected to a series of multiplier elements (also referred to herein as multiplier units) which split the two-layer molten polymer stream into many layers and is thusly deposited onto a cooling roll stack to form a clear film or sheet. This clear film or sheet is then thermoformed into a three-dimensional article or packaging and is subsequently heat set on the mold to promote crystallization and to remove residual stresses which may otherwise cause shrinkage or warpage during sterilization. The thickness of each individual layer comprising the semi-crystalline polymer is critical since the objective is to promote crystallization in each crystallizable layer to the full extent, yet physically constraining the crystal growth size to small spherulites via the second polymeric layer boundaries on top and bottom. After a medical device has been sealed into the three-dimensional article or packaging and subjected to autoclave steam sterilization, the resulting article remains relatively clear, with little to no package warpage and yet is as tough if not tougher than its non-crystallized, amorphous analogs.DETAILED DESCRIPTION

[0009] The present disclosure may be understood more readily by reference to this description as well as to the examples included herein. Tn addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments and examples described herein. However, those of ordinary skill in the art will understand the embodiments and examples described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein.

[0010] As used herein and in the appended claims, an element or component that “comprises” or “includes” one or more specified components or steps means that the element or component includes the specified component(s) alone or includes the specified component(s) together with one or more additional components. An element or component that “consists of’ one or more specified components means that the element or component includes only the specified component(s). An element or component that “consists essentially of’ one or more specified components means that the element or component consists of the specified component(s) alone or consists of the specified component(s) together with one or more additional components that do not materially affect the basic properties of the element or component. Whenever a range is disclosed herein, the range includes independently and separately every member of the range extending between any two numbers enumerated within the range. Furthermore, the lowest and highest numbers of any range shall be understood to be included within the range set forth.

[0011] As used herein “film,” “sheet,” or “film or sheet” will be used interchangeably. Typically, the designation of “film” would reflect a thinner material than a “sheet;” however, this disclosure applies to both, and the terms will be used interchangeably without distinction.

[0012] Clear, rigid medical packaging is most often made from an amorphous polyester that has been modified in the polymerization reactor by the resin supplier such that it is no longer crystallizable. The most common version of this amorphous polyester is glycol-modified copolyester (PETG). PETG thermoforms well and has sufficient free volume engineered into its morphology such that it generally retains its strength and clarity after sterilization processes at elevated temperatures. These sterilization procedures include ethylene oxide and gamma radiation, amongst others, where the elevated temperature during sterilization must remain below the material’s glass transition point (Tg) or package shrinkage and warpage, among other detrimental effects, result. However, PETG cannot be steam sterilized since warping and subsequent package failure from a probable loss in sterility begins to occur near PETG’s glass transition temperature of approximately 80 degrees Celsius.

[0013] To keep the cost of rigid medical packaging to a minimum, or to tout improved recyclability, certain extrusion companies offer lower-cost alternatives to PETG, such as thermoformable film or sheets made from polyester (PET) or amorphous PET (APET). While the semantics for these materials can be confusing, PET and APET are chemically close in composition to one another. While the acronym implies a homopolymer, PET often contains between approximately 1 to 2.5% modifier, where the modifier is often isophthalic acid (IPA). APET historically contains slightly more modifiers than PET at approximately 2.5 to 4.5% modifier content on a molar basis. Similarly, to better codify the chemistry of PET suitable for the RIC stream 1 PET recycle industry (RIC#1, resin identification code for polyesters), the state ofCalifornia limited the composition of PET or APET that can be recycled in the stream 1 PET recycle code as a polyester containing a maximum of 10% “other” modifier beyond the terephthalic acid and ethylene glycol base monomers used to make PET. The higher level of IPA modifier, or other monomer modifiers, in APET slows the rate of crystallization. PET can be extruded up to approximately 0.070 inches thick and remain clear whereas APET can be extruded up to a maximum of about 0.150.” Beyond this thickness, the residual heat from the extrusion process cannot be removed from the extrudate sheet quickly enough, leading to the generation of crystallization. Thermally-induced crystallization usually contains relatively large-sized crystals, which, when present in film or sheet, leads to the generation of haze. For practical purposes, an average crystal size larger than the wavelength of visible light lead to haze. Fully crystallized sheet results in turning the sheet from clear (in its amorphous morphological state) to opaque white in the fully crystallized state. PET sheet extruded below 0.070 inches and quenched quickly is amorphous, clear, and begins to distort at approximately 80 degrees Celsius (the glass transition point for PET). In contrast, a PET sheet that has been thermally crystallized (which is hazy, even to the point of being opaque white) no longer softens or sags during thermoforming at 80 degrees Celsius, but instead, generally retains its stiff shape up to a temperature as high as its melt point of about 245 degrees Celsius for “bottle grade” PET. These approximate values are easily obtained via testing with a Perkin Elmer differential scanning calorimeter (DSC) at a scan rate of 20 degrees Celsius per minute and are well-known by those skilled in the art. Since PET and APET are so close in chemical composition and properties, the PET designation will be used from henceforth for simplicity but generally describes either or both materials to within a close approximation. The crystallization half times suitable for some aspects of the present disclosure are between 5 seconds and 30 minutes (via DSC, SALLS or XRD test methods). In contrast, PETG contains multiples ofthe aforementioned levels of polymer chain modification (comonomer modification, often between 28 to 33% on a molar standpoint on a diol basis) that renders it as being truly amorphous. PETG cannot be crystallized, evidenced by the fact that it has been extruded at linch thick while remaining clear. The crystallization half-time of PETG is often measured as greater than 10,000 hours when the test is often terminated. PETG therefore shows a glass transition temperature of about 80 degrees Celsius but no melt point during DSC testing since it is essentially amorphous and cannot be crystallized.

[0014] The preceding paragraph describes two morphological states of PET: amorphous and crystalline, where the crystallinity has been initiated or allowed to occur, by thermal means. Other routes, such as chemical or solvent means, can also lead to crystallization of similar characterization. Crystals in PET are often relatively large, leading to haze, opacity, and brittleness in articles that have been crystallized. A third or quasi-morphological state can also be obtained. Mechanically stretched or strain-oriented PET leads to small crystallites, also called pseudocrystals or spherulites by some. These small pseudo-crystals have the effect of retaining clarity (because the pseudo-crystal size is smaller than the wavelength of light) yet they increase the measured heat distortion temperature to values much above the glass transition temperature of about 80 degrees Celsius because small crystals are present. In addition, when the strain-hardening region is reached, these small pseudo crystals have the added effect of improving toughness, often well beyond the levels tested with amorphous morphologies. In contrast to PET, when PETG film or sheet is oriented, it forms shrink film, without the formation of the small pseudo-crystals. Therefore, PETG, either in the oriented or amorphous state, still cannot be used in applications requiring rigid stability above its glass transition temperature of 80 degrees Celsius. This definition of PETG assumes the optimal amount of modifier has been added such that no crystallization isformed during the aforementioned tests. It should be noted that some casual use of the acronym PETG can, in some instances, refer to modification levels beyond the crystallization curve apex and therefore can still be crystallized. Similarly, this situation could also occur when mixing, for example, 70% PETG with 30% PET, as well as many other ratios, dilutes the modifying diol beyond those leading to the most amorphous targets.

[0015] In embodiments of the current disclosure, it is the desired end state of the final article or package to contain the small pseudo crystals described above, yet to achieve this state not by mechanical means but by thermal means. While thermally-induced crystallization normally leads to large-sized crystals with undesirable properties needed for clear medical packaging, the current disclosure identifies the process of retaining small pseudo crystals by limiting the amount of polymer present in the crystallizable layer to essentially retard or stop additional crystal growth. In one embodiment, the microlayer thickness is kept between 100 to 300 nanometers, or 200 to 400 nanometers, or 300 to 500 nanometers, or 400 to 600 nanometers, or 500 to 700 nanometers, or 600 to 800 nanometers, or 700 to 900 nanometers, or 900 to 1100 nanometers, or 1100 to 1500 nanometers, or 1500 to 2000 nanometers, or 2000 to 2500 nanometers, 2500 to 3000 nanometers, or preferably below 400 nanometers, or more preferably below 350 nanometers. In another embodiment, it is further recognized that the final microlayer thickness, in the part to be sterilized, achieves its total thickness by the combination of two processes: from both multiplier units and by additional thinning via stretching that occurs during the thermoforming process, where the amount of stretching that occurs during thermoforming can change depending on the package design and draw ratio or depth of draw for the target part.

[0016] In embodiments of the current disclosure, a combination of techniques can be used to determine a targeted layer thickness. In this instance, the microlayer approach is used to producelayer thicknesses as recited in the preceding paragraph or slightly thicker than those described in the preceding paragraph, yet optionally, a secondary mechanical stretch of the film can be used to effectively reduce the final film layer thickness, post stretching, or even post thermoforming, to the same final layer thickness that retards further crystal growth as intended in the current disclosure. As will appreciated, the final crystalized layers or microlayers of this disclosure will not be fully crystallized but have pseudo-crystals or spherulites of the thermoplastic polymer distributed in an amorphous phase of the thermoplastic polymer. For example, there could be 10 to 35 percent crystal content and 65 to 90 percent amorphous content. For example, there typically will be about 25 percent crystal content and about 75% amorphous content.

[0017] In embodiments, the practitioner can employ both the multi-layered approach coupled with the mechanical stretching operation. While spherulite size is limited in the Z direction via Cartesian or Gaussian coordinates due to the presence of a different polymer above and below this layer (and for all layers), it is recognized that crystal growth in the film or sheet planar or XY direction is still possible. Such an orientation is expected to cause birefringence or a difference in the refractive index in different directions, potentially leading to the transmission or reflectance of undesirable color. Employing a slight degree of mechanical stretching orients the polymer chains in the XY planar direction, an action which mechanically solidifies the spherulites, retards planar crystalline growth, resulting in less color generation for reflectance and transmission.

[0018] In embodiments of the current disclosure, a main extruder and a co-extruder can be used to form an “AB” molten polymer layer, each with layer thicknesses X and Y, respectively, where layers A and B contain different polymer chemistries or intrinsic viscosities. After encountering the first multiplier unit, the initial AB layer becomes an AB AB layer with relative thicknesses of 0.5*X and 0.5*Y, respectively. The ABAB, four-layer molten stream thenencounters another multiplier unit whereupon an eight-layer molten stream is formed. This procedure is repeated with multiple multiplier units placed in series until the desired film microlayer thickness is achieved. In embodiments, the ABAB, four-layer molten stream exiting multiple multiplier units can thereafter enter a second co-extrusion block where a third co-extruded layer can be added to the exterior of one or optionally both surfaces to form a CABABC multilayered stream. Such constructs are often important for altering solely the properties on the exterior surface, including examples like altering the coefficient of friction (using denest, anti-block, or slip additives) or including ultra-violet stabilizing additives within the outer “C” layer of thermoplastic. The four-layered molten stream just discussed is representative of four or many more layers in the thousands.

[0019] In this disclosure, a multiplier unit is typically a static, non-moving, heated but otherwise non-energized part with a (normally vertical) blade. This blade splits and separates a molten polymer stream into two halves, which will be designated as a left-half stream and a righthalf stream. Since the polymer stream is typically contained in a cylindrical, high-pressure pipe, once the blade splits the molten polymeric stream, both the left half and right half streams are temporarily crescent-shaped molten streams that are mirror images of one another. Directly behind the blade are two ramps, a left ramp and a right. The left ramp directs and manipulates the left half stream upward and spreads to the right such that the left half molten stream becomes a top half molten stream. Similarly, the right ramp directs and manipulates the right half stream downward and spreads to the left such that the right half molten stream becomes a bottom half molten stream. In this one multiplier element, the stream has therefore been split and manipulated such that the left ends up on top and the right ends up on the bottom. For a homogeneous polymeric stream, the multiplier element has no effect. However, when the molten stream feeding the multiplier elementutilizes a co-extruded stream, with a top layer A and a bottom layer B, the effect is to turn an AB (two) layer molten stream entering the stream splitter into an ABAB (four) layer molten stream exiting the multiplier unit, thusly “multiplying” the number of stream layers from two to four. This description used orientation verbiage such as vertical, right, left, upward, downward, etc., to illustrate certain points but the multiplier unit could be oriented differently to achieve the same effect of splitting and stacking layers with the intended multiplication effect. From a rheological standpoint, note that the Reynold’s number is sufficiently low to always maintain laminar flow of the polymeric stream so stream interlayer mixing does not occur. In other words, and AB layer configuration always remains as two distinct layers with an interface and no turbulent mixing of the two distinct layers. Also, any of the following phrases are used interchangeably to describe the above function: multiplier element, multiplier unit, multiplier segment, multiplier stream splitter, stream splitter, layer stacker, etc.

[0020] In embodiments, co-extrusion blocks exist which split streams into microlayer-like layers in the co-extrusion block without necessarily utilizing multiplier units placed in series. These co-extrusion blocks, optionally coupled with multiplier units, optionally coupled with mechanical stretching, can be used such that the plurality of these steps results in the desired film microlayer thickness.

[0021] In embodiments of the current disclosure, a main extruder and two co-extruders can be used to form an “ABC” molten polymer layer, each with layer thicknesses X, Y, and Z, respectively, where layers A, B, and C contain different polymer chemistries or intrinsic viscosities. After encountering the first multiplier segment, the initial ABC layer becomes an ABCABC layer with relative thicknesses of 0.5*X, 0.5*Y and 0.5*Z, respectively. TheABCABC, six-layer molten stream then encounters another multiplier unit whereupon a 12-layer moltenstream is formed. This procedure is repeated with multiple multiplier units placed in series until the desired film microlayer thickness is achieved.

[0022] In embodiments, a main extruder and as many as 12 coextruders can be utilized, and subsequently subjected to multiplier units, to form many individual microlayers of multiple chemistries.

[0023] It is also recognized that certain types of co-extrusion feed blocks contain stream dividers such that an ABC layer, with stream dividers present, usually before the co-extruded molten streams join, can lead to ABCBA or ABCB or BCBA, etc., layers. Such stream dividers, not to be confused with the multiplier segments that typically split the entire molten stream with all layers present, are also part of certain embodiments of the current disclosure.

[0024] In embodiments of the current disclosure, the polymeric ratio of the AB streams can be 50% of stream A and 50% of stream B. In other embodiments, the ratios of the two streams can be adjusted by either speeding up or slowing down one of the two extruders relative to the other one to obtain relative ratios of 40% stream Ato 60% stream B, or 30 / 70, or 20 / 80, or 10 / 90, or 5 / 95, or 60 / 40, or 70 / 30, or 80 / 20, or 90 / 10 or 95 / 5. For example, stream A can be from 20% to 95% of an AB stream. Similarly, adding additional layers via additional co-extruders for a C layer, a D layer, etc., can still employ various ratios or extruder speeds to alter the percentage of the layer in each stream to something beyond equal portions as needed. In summary, the semi-crystalline content in the final package can be less than 100% of the final package, due to the AB or ABC or other present layers, and yet can still be properly crystallized such that the final package remains relatively clear without a significant degree of warpage post steam sterilization even with less than 100% semi-crystalline resin content is present.

[0025] In embodiments of the current disclosure, one of the two layers in an AB film construct can contain a semi-crystalline polymer, and the second layer contains an amorphous polymer. After going through several multiplier segments, as many as 50, or 100, or 200, or 400, or 600, or 1000 or 1500, or 2000 layers or more can be made wherein the final number of layers is determined by the initial film or sheet thickness and the target layer thickness in the final product. For example, there can be 50 to 2000 layers, or 50 to 1500 layers, or 100 to 2000 layers, etc. In other embodiments, one of the two layers in an AB film construct can contain a semi-crystalline polymer and the second layer also contains a semi-crystalline polymer. In cases where the two layers are the same material, they might not properly act as boundary layers which restrict crystalline size growth. In these instances, the second layer can be of a different chemistry, or the same chemistry that possesses a different intrinsic viscosity (IV) to keep the layers separate. After going through several multiplier segments, as many as 50, or 100, or 200, or 400, or 600, or 1000 or 1500, or 2000 layers or more can be made wherein the final number of layers is determined by the initial film or sheet thickness and the target layer thickness in the final product. For example, there can be 50 to 2000 layers, or 50 to 1500 layers, or 100 to 2000 layers, etc.

[0026] In embodiments of the current disclosure, one of the three layers in an ABC film construct can contain a semi-crystalline polymer, a second layer can contain an amorphous polymer, and a third polymer, amorphous or semi-crystalline, wherein one of the ABC layers is optionally a tie layer to improve compatibility between the other two layers. After going through several multiplier segments, as many as 50, or 100, or 200, or 400, or 600, or 1000 or 1500, or 2000 layers or more can be made wherein the final number of layers is determined by the initial film or sheet thickness and the target layer thickness in the final product. For example, there can be 50 to 2000 layers, or 50 to 1500 layers, or 100 to 2000 layers, etc. It is recognized that layers Aand B therefore can optionally be compatible with one another, but this feature is not obligatory and can optionally be overcome via a compatibilizing tie resin which typically is compatible with both of the other two-layer chemistries.

[0027] In embodiments of the current disclosure, one of the two layers in an AB film construct can contain a semi-crystalline polymer and the second layer can contain an amorphous polymer. Typically, the two materials will be selected such that, when blended, they form a clear, molten blend. If the two materials are not miscible, then when blended, the resulting blend will be hazy. This feature of making a clear, molten blend is most important for the reuse of film or sheet edge trim for reprocessing. Therefore, it is recognized that when 100% virgin resin is used in layer A and layer B initially, when regrind is added back into each subsequent layer, either the semicrystalline layer will be diluted with some percentage of miscible amorphous resin or the amorphous layer will be diluted with some percentage of miscible semi-crystalline resin, depending to which stream the edge trim regrind is directed. In embodiments, the edge trim scrap can be refed back into the semi-crystalline layer, and in alternative embodiments, the edge trim scrap can be refed back into the amorphous layer. The above scenario can be replicated with all permutations for situations where additional C layers, or D layers, etc., are part of the initial film or sheet construction. For embodiments where any layer containing a portion of recycled or refed edge trim needs to remain clear, it is preferred that the difference in the Hansen or Hildebrandt solubility parameters of the two polymers be less than 2.0 or preferably less than 1.5 to retain clarity from a polymer mixing and miscibility standpoint. Utilizing a different but remotely similar metric, for embodiments where any layer containing a portion of recycled or refed edge trim needs to remain clear, it is preferred that the difference in the thermodynamic chi factor of the twopolymers be less than .013 or preferably less than 0.01 to retain optimal clarity from a polymer mixing and miscibility standpoint.

[0028] In embodiments, the A layer can be PET and the B layer can be PETG. While the edge trim scrap may need additional twin screws or other processing to form a clear blend prior to extrusion into the AB film or sheet, the resulting product does retain proper clarity.

[0029] In embodiments, the A layer can be PET, the B layer can be PETG, and the A layer is split in or near the coextrusion block to form an ABA film construction for subsequent layer multiplication. In this situation, the A layer remains on the outside of the film so that the PET chemistry always remains on the outside of the film and also on the outside of the thermoformed package. This construction aids recyclability in the resin identification code (RIC) #1 stream, dedicated to PET. It is well known to those in the post-consumer recycling industry that exposed surfaces of PETG film or sheet become sticky at the temperatures experienced in the recycle flake process and gum up or form undesirable agglomerations above about 2 to 3% total PETG content. With ABA film layer constructs, with the A layer containing PET in this embodiment, the PETG layer is contained and covered with a PET layer that does not become sticky in the recycle flake process, thus improving recyclability. This case remains even after ABA layer multiplication where ABAABA and additional multiplication to hundreds or thousands of layers. Similar concepts are recognized with the addition of other layers including C layers, D layers, etc.

[0030] Using methods common to those skilled in the art, rigid medical packaging thermoformed today typically utilizes PETG, PET, or APET film or sheet that all contain amorphous morphology and therefore process similarly with similar characteristics. Specifically, PETG, PET, and APET film or sheet are all clear and amorphous and are heated to a surface temperature of about 137 to about 171 degrees Celsius (about 280 to about 340 degrees Fahrenheit)prior to thermoforming into a rigid medical package. All of these packages made from any of these three substrates would also be clear and retain their shape during sterilization as long as the temperature does not exceed about 80 degrees Celsius. Certain protocols for steam sterilization specify 121 degrees Celsius as the target temperature. Clear, rigid medical packages made according to today’s methods would not survive this level of steam sterilization. One with limited experience in the art might try to alleviate the aforementioned low heat distortion temperature of PET or APET by crystallizing the packaging after thermoforming without employing the methods in this disclosure. A PET package can therefore be heated while still on the thermoforming mold to crystallize said article. While thermally induced crystallization can occur at a range of times and temperatures, for PET the maximum rate of crystallization would occur at about 175 to 185 degrees Celsius. After several minutes of heating and subsequent cooling, the resulting article can withstand steam sterilization at 121 degrees Celsius without deformation, but the thermoformed article would no longer be fit-for-use as rigid medical packaging because it would have become opaque white (no longer clear, which is typically a necessary feature) and it would become brittle. Opaque, brittle packages cannot withstand the various transportation steps between the sterilization facility and the operating room and would possibly break and jeopardize device sterility.

[0031] Concerning the mechanically stretched or strain-oriented state of PET, when stretched beyond about 4 to 5 times its original dimensions, an effect, herein called strain hardening, can occur. When strain hardening occurs in PET or other semi-crystalline materials, it becomes much more difficult to stretch it farther. Attempts to stretch it farther often lead to tensile strength failure. In embodiments, the present disclosure therefore can involve partially stretching the film or sheet via mechanical means (in its two-dimensional or flat form) but leaving thecapability of the film or sheet to be stretched farther during the thermoforming process. The point of strain hardening is therefore recognized as approaching the approximate upper limit for this novel process. The sum of the pre-stretching or partial stretching before being formed into a three- dimensional article plus the additional stretching that occurs from the thermoforming process is additive and therefore remains below, at, or just beyond the strain hardening point in finished articles. This is the upper limit for stretching the crystalline or semi-crystalline substrates. In embodiments, it is desirable to stretch into and beyond the strain hardening initiation point as a myriad of product property improvements occur (modulus gain, toughness gain, suppression of notch sensitivity, chemical resistance improvement, barrier property enhancement, recyclability processing improvement, an increase in the continuous use temperature, slowing of physical aging, raising the Q10 factor, etc.). In this case, essentially all of the small spherulites, smaller than the wavelength of light, were caused by the sum of the two stretching steps (mechanical stretching then stretching during the thermoforming process caused by the rubbery, planar film or sheet being pulled over the mold). In embodiments of the present disclosure, the small-sized spherulites are due to the summation of the stretching process plus the remaining crystallization that was completed thermally while the article or package remained on the thermoforming mold (i.e., heat setting). In other embodiments, the small-sized spherulites are due solely to the thermally-activated crystallization where the spherulite’s size is limited by the other polymeric boundaries on the top and bottom planar surfaces via the microlayer construction. In yet other embodiments, the smallsized spherulites are due the summation of three processes: mechanically stretching the film, further stretching the film during thermoforming and thermally-activated crystallization where the spherulite’s size is limited by the other polymeric boundaries on the top and bottom planar surfaces via the microlayer construction. 1

[0032] A film or sheet substrate naturally possesses the three dimensions of length, width, and height (or thickness). However, for the purpose of the current disclosure, these substrates will be referred to as having two dimensions where the height or thickness of said film or sheet has not been altered as made (extruded, calendered, blown, etc ). The planar direction of the film or sheet can be expressed herein as the x- and y-directions in Cartesian or Gaussian coordinates and the height or thickness as the z-direction. The two-dimensional film or sheet remains flat as made. In contrast, a three-dimensional film, sheet, or article is defined as a two-dimensional film or sheet that has been manipulated such that the height of the planar film or sheet has been altered in the z- direction, different from which it was made. Manipulation means thermoforming, vacuum forming with plug assist, pressure forming, matched mold forming, hydraulic bladder forming, drape forming, etc., where the (optional) heating, stretching, and subsequent (optional) cooling steps add contours in the z-direction that are at least 10% out-of-plane versus how the flat film or sheet was initially made. In embodiments, strain hardening makes sheets more difficult to form, thereby necessitating higher forces (greater pressure differential) than those available through normal vacuum forming, requiring pressure forming, matched mold forming, hydraulic bladder pressing, or use of a plug assist with close tolerance to the mold, etc.

[0033] In one embodiment of the present disclosure, molten polymeric film and sheet comprise or contain linear or branched polymeric strands that are deposited in random orientations when deposited under low to no stress environments, leading to isotropic properties. This molten film or sheet is quickly quenched to freeze the molecular orientation in the random state, leading to high clarity in the film or sheet. Herein the term “quickly quenched” refers to cooling the molten polymer near, to, or below its glass transition temperature in a time period that is a small fraction of its crystallization half-time for crystalline or semi-crystalline polymer types. In certainconditions where the film or sheet is not quickly quenched, crystals can form undesirably from this thermally-activated mechanism which grows to a relatively large size. When the large-sized crystal is larger than the wavelength of visible light (400 to 700 nanometers), visible light is scattered in non-randomized directions which leads to haze and eventually opacity when the size and quantity of large crystals exist. It is the purpose of the present disclosure to avoid large crystals leading to haze and possible opacity from crystal sizes larger than about 2000 nanometers, or 1500 nanometers, or 1000 nanometers, or 700 nanometers, or more preferably below 400 nanometers, or most preferably below 350 nanometers. Clarity is best maintained when the size of crystals, crystallites, pseudo-crystals, or spherulites are below 400 nanometers. For the purposes of the present disclosure, a crystal is herein defined as initially random polymeric strands with relatively high free volume or interstitial pocket void space between the polymer strands which subsequently become more ordered or stacked into smaller areas that have densified to possess less than the maximum amount of free volume and which now, post crystallization, contain a higher fraction of both dipole and van der Waals forces between the adjacent polymer strands (from closer and more aligned orientation), leading to non-linear measurements during DSC testing at constant energy input. These crystals also have a true melt temperature that is higher than the first inflection point (the glass transition temperature) of the randomized, non-oriented sections of the polymer, measurable and quantifiable during DSC testing. Crystallites, pseudo-crystals, or spherulites are herein defined as small crystals, less than 700 nanometers in size, that also manifest themselves during DSC testing by affecting non-linear measurements during DSC testing at constant energy input whereas a completely amorphous or randomized arrangement of polymeric strands does not show a melt point but only a glass transition temperature during the first DSC scan.

[0034] In one embodiment, the crystal size is measured as the radius of the calculated hydrodynamic volume. In other embodiments, since the film can be intentionally stretched or some degree of orientation in the film is generated during film neck-down as the extrudate exits the die, the crystal size is measured as the length of the longest direction according to the crystal’s aspect ratio. In other embodiments, the crystal size is measured as the length of the shortest direction according to the crystal’s aspect ratio. In other embodiments, the crystal size is measured as the average of the dimensions for the crystal’s aspect ratio. In other embodiments, the crystal size is limited to a maximum based on the physical properties of the film or sheet. In other words, physics dictates that a crystal size is below 400 nanometers when an article remains clear, yet crystals are known to be present based on the measured heat distortion temperature or testing by differential scanning calorimetry (DSC).

[0035] In embodiments, the crystallization mechanism mentioned above can also occur due to mechanical forces being induced in a film or sheet under certain environmental conditions. These pseudo-crystals, induced by mechanical means tend to be smaller and more easily controlled via mechanical means than thermal means for monolithic sheets or layered sheets via a multiplier if the layers were not made sufficiently thin. When the mechanical force or stretching occurs in one direction, whether that be in line with the extrusion direction, herein called machine direction orientation, or across the film or sheet web, herein called the transverse direction orientation, usually leads to anisotropic properties. The force to tear the film, for example, will be different when tom in the general direction of the orientation versus a tear force measured perpendicular to the direction of orientation. It is, therefore, a preferred embodiment of the present disclosure to stretch or orient the film or sheet in both the x and y directions in a bi-axial manner to bettermaintain isotropic properties, of which the tear force previously mentioned is one of many properties thusly affected if any stretching is utilized.

[0036] Under certain aspects of the present disclosure, it is expected that a small amount of haze might be present on some limited portions of the three-dimensional package after steam sterilization. For example, with a film that has been stretched 2.5 times its original dimensions and then thermoformed, it is recognized that the package design, specifically the depth of draw or lack thereof, becomes a factor. In areas where the pre-stretched film is farther stretched, small pseudocrystal formation will be maximized. However, on other parts of the same package, little to no additional stretching might occur (i.e., on flat parts of the package). These parts of the package will contain some quantity of pseudo crystals but will not be as close to the strain hardening point as the part of the package that required more stretching. Such a part could still warp when exposed to elevated temperatures. While not obligatory for this art, in some aspects of the current disclosure the article is heat set while it remains on the mold at or above the intended use temperature. For example, under one sterilization protocol, autoclave steam sterilization occurs at 121 degrees Celsius. Articles undergoing this protocol should be thermoformed and then heat set at, for example, 125 degrees Celsius, or higher, for up to several minutes. Performing this step prior to steam sterilization will lead to a part that remains relatively warp-free, generally clear, and retains its tough characteristics.

[0037] Under certain other aspects of the present disclosure, it is expected that a small amount of haze might be present on some limited portions of the three-dimensional package before or after steam sterilization. Due to quality control or other issues, the thickness of a certain microlayer might obtain, for example, 700 nanometers or thicker. In this case, upon thermal heat setting and crystallization growth activation, the crystals can grow to a size that is slightly largerthan the wavelength of light. In this case, complete opacity is not anticipated but only a portion of undesirable haze. Proper quality control, considering thickness variation over time due to specific extruder / cooling line capability, would relieve this issue. Further, for microlayer thicknesses between 400 and 700 nanometers, it is possible to see specific colors, or even a color flop (color change at different viewing angles) where differences in the directional refractive indices, coupled with excessively large crystal structures, begin to bend light, showing prismatic colors, in unpredictable ways. Such issues, if undesirable, can be alleviated via additional layer thinning and by keeping the difference in the refractive index of the two layers as close as possible or below a difference of 0.03, or more preferably below a difference of 0.02, or most preferably below a difference of 0.01.

[0038] In the various aspects of this disclosure, the resulting three-dimensional article typically has a haze value of less than 10% (or less than 8%) as measured by ASTM DI 003 and / or a measured light transmission of greater than 70% (or greater than 75%) as measured by ASTM D1003, and the article retains one or both of these properties even after heating to a temperature above the glass transition temperature but less than the melt temperature of the thermoplastic polymers from which the article is formed, or less than the lowest melt temperature of the thermoplastic polymers.

[0039] In another aspect of the current disclosure, a mirror-type effect is visible due to reflection from interfacial layers with different refractive indices. Such issues, if undesirable, can be alleviated via additional layer thinning and by keeping the difference in the refractive index of the two layers as close as possible or below a difference of 0.03, or more preferably below a difference of 0.02, or most preferably below a difference of 0.01.

[0040] While not an obligatory step, in some aspects of the current disclosure, the article is heat set while it remains on the mold at or above the intended use temperature. This practice not only heat sets the material to minimize or prevent warpage up to the heat set temperature, but it also promotes crystallization in the thin layers to achieve high-temperature use. For example, under one sterilization protocol, autoclave steam sterilization occurs at 121 degrees Celsius. Articles undergoing this protocol should be thermoformed and then heat set at, for example, 125 degrees Celsius, or higher, for up to several minutes. Performing this step prior to steam sterilization will lead to a part that remains relatively warp-free, generally clear, and retains its tough characteristics post-steam sterilization.

[0041] It should be noted that steam sterilization is not an obligatory endpoint for the current disclosure. Articles made from pre-stretched sheets, then thermoformed, then heat setting leads to an overall tougher product than packages made from amorphous PET or PETG film or sheet. Similarly, heat setting is also an optional element for this art. Articles made from prestretched sheet, then thermoformed, without heat setting also yield an overall tougher product than packages made from amorphous PET or PETG film or sheet. In other words, PET that has been partially or fully oriented generally has a higher notched Izod impact value than PET or PETG that has not been oriented. Further, the final article in the present disclosure need not be intended exclusively for rigid medical packaging. Any thermoformed article with three-dimensional character using microlayers with optional pre-stretched sheets is applicable in the current disclosure.

[0042] In other embodiments, it should be further noted that steam sterilization is not an obligatory endpoint for the current disclosure. Articles made from film or sheet with microlayers of proper thickness, then thermoformed, then heat setting lead to an overall tougher product thanpackages made from amorphous PET or PETG film or sheet. Similarly, heat setting is also an optional element for this art. Articles made from film or sheet with many layers of proper thickness, then thermoformed, without heat setting also yield an acceptable product versus packages made from amorphous PET or PETG film or sheet. Further, the final article in the present disclosure need not be intended exclusively for rigid medical packaging. Any thermoformed article with a three-dimensional character using film or sheet with many layers of proper thickness is applicable in the current disclosure.

[0043] In embodiments of the current disclosure, sterilization methods beyond steam sterilization that utilize elevated thermal conditions are improved. For example, in ethylene oxide sterilization (ETO), an elevated thermal climate is used with amorphous packages, but the temperature must remain below the material’s glass transition temperature. In the current disclosure, the presence of the small spherulites enables increased temperatures during ETO sterilization (i.e., more severe sterilization protocols) and other sterilization methods which can result in faster sterilization cycle times, higher efficacy post sterilization (fewer sterilization cycles or repeated processing from undesirable biological indicator results) and a tougher part since sterilization above the material’s glass transition temperature leads to essentially no aging in the amorphous regions between the spherulites.

[0044] The preceding description focused on PET packages because medical-grade PET resin tends to be less expensive than medical-grade PETG resin, yet packages made with PET according to the process described herein result in a package with superior properties when compared to PETG, which has heretofore been recognized as the preferred material for use in clear, thermoformed rigid medical packaging. It is recognized in the art that oriented film or sheet fromother semi-crystalline polymers may also yield similar or better properties as oriented film or sheet from PET but at a higher raw material price point.

[0045] In embodiments of the present disclosure, the suitable crystalline or semicrystalline polyesters can be either aromatic or aliphatic in nature and comprise, but are not limited to, polyethylene terephthalate (PET), amorphous polyethylene terephthalate (APET), glycol- modified polyethylene terephthalate (PETG), acid-modified polyethylene terephthalate (PETA), Polycyclohexylenedimethylene terephthalate (PCT), glycol-modifiedPolycyclohexylenedimethylene terephthalate (PCTG), acid-modifiedPolycyclohexylenedimethylene terephthalate (PCTA), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), Polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polybutylene adipate-co-terephthalate (PBAT), polytretramethylenecyclobutylene terephthalate (PCTM), polycyclohexanedimethyl cyclohexanedicarboxylate (PCCD), polycyclohexylene dimethylene cyclohexanedicarboxylate (PCCE, copolyester ether elastomer), polycyclohexanedimethylene-co-isosorbide terephthalate, and copolymers, isomers and blends thereof. The aforementioned polymers can also be used to form amorphous layers that intersperse with the crystalline or semi-crystalline layers, as will be apparent to those skilled in the art based on this disclosure.

[0046] In embodiments of the present disclosure, the polymeric composition can contain both primary and secondary diol or diacid modifying monomers and additional comonomers, including multi-functional branching monomers, either aromatic or aliphatic in nature, and comprise cyclohexane dimethanol, butanediol, propanediol, neopentyl glycol, spiroglycol, isosorbide, 2, 2, 4, 4 - tetramethyl-l,3-cyclobutanediol, diethylene glycol, ethylene glycol,bisphenol A (BPA), branchers (TMA), pentaerythritol, 2,5-hydroxymethyl tetrahydrofuran or polyethylene glycol (PEG).

[0047] In embodiments of the present disclosure, the diol component of the polyesters in the blends of the disclosure may contain one, two, three, or more residues of modifying diols. Examples of modifying diols include propylene glycol, 1,3 -propanediol, 2,4-dimethyl-2- ethylhexane-l,3-diol, 2,2-dimethyl-l,3-propanediol, diethylene glycol, 2-ethyl-2-butyl-l,3- propanediol, 2-ethyl-2-isobutyl-l,3-propanediol, 1,3 -butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2,4-trimethyl-l,6-hexanediol, thiodiethanol, 1,2-cyclohexanedimethanol, 1,3 -cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylylene glycol, polyethylene glycol, diethylene glycol, polytetramethylene glycol, 2,2,4,4-tetramethyl-l,3- cyclobutanediol, and combinations thereof.

[0048] In embodiments of the present disclosure, one, two, three, or more dicarboxylic acids which may be used with or instead of terephthalic acid, include phthalic acid, isophthalic acid, furandi carboxylic acid (FDCA), 1,4-, 1,5-, 2,6-, and 2,7-naphthalenedicarboxylic acid, 1,3-, 1,4-cyclohexanedicarboxylic acid (which may be cis, trans or a mixture thereof), cyclohexanediacetic acid, trans-4,4’-stilbenedicarboxylic acid, 4,4’ -oxy dibenzoic acid, 3,3’- and 4,4’-biphenyldicarboxylic acids, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, suberic acid, pimelic acid, nonane, decane, or dodecanedicarboxylic acids. The copolyester may be prepared from one or more of the above dicarboxylic acids. It should be understood that the use of the corresponding acid anhydrides, esters, and acid chlorides of these acids is included in the term “di carboxylic acid.” The “residue” of the dicarboxylic acids described herein is that portion of the diacid which constitutes a portion of a diester of the diacid. The diacid residues may be derived from the dicarboxylic acid, dialkyl esters thereof, e g., dimethylterephthalate and bi s(2-hydroxy ethyl) terephthalate, acid chlorides thereof and, in some cases, anhydrides thereof.

[0049] In embodiments of the present disclosure, the polyamide composition can contain both primary and secondary diamines or diacid-modifying monomers and additional comonomers, including multi-functional branching monomers, either aromatic or aliphatic in nature.

[0050] The polymer blends of the current disclosure may further comprise one or more additives in amounts that do not adversely affect the resulting blend properties such as haze. Examples of additives include antioxidants, melt strength enhancers, chain extenders, flame retardants, fillers, acid scavengers, dyes, colorants, pigments, anti-blocking agents, flow enhancers, impact modifiers, antistatic agents, processing aids, mold-release additives, plasticizers, slip agents, stabilizers, waxes, UV absorbers, optical brighteners, lubricants, pinning additives, foaming agents, nucleators, glass beads, metal spheres, ceramic beads, carbon black, cross-linked polystyrene or acrylic beads, and the like. Colorants, sometimes referred to as toners, may be added to impart a desired neutral hue and / or brightness to the polyester blends. Representative examples of fillers include calcium carbonate, talc, clay, mica, zeolites, wollastonite, kaolin, diatomaceous earth, TiCh, NH4CI, silica, calcium oxide, sodium sulfate, and calcium phosphate. Titanium dioxide and other pigments or dyes may be included. In another embodiment, crystallization seeding is employed utilizing various additives including linear low- density polyethylene or polypropylene additives.

[0051] In embodiments of the present disclosure, the crystalline or semi-crystalline polyesters have an inherent viscosity (IV) ranging from about 0.5 to about 1.2 dL / g, when measured at 25° C. using 0.50 grams of polymer per 100 mL of a solvent consisting of 60 weight 1percent phenol and 40 weight percent tetrachloroethane as generally described in ASTM Method D2857-95.

[0052] The glass transition temperature can be measured by conventional methods. For example, the glass transition temperature of the crystalline or semi-crystalline polyesters can be measured according to ASTM D 3418.

[0053] In one aspect of the present disclosure, the branching agent comprises a multifunctional acid or multifunctional alcohol having at least three acid or alcohol groups or a combination of acid and alcohol groups including, but not limited to, trimesic acid, trimellitic acid, citric acid, tartaric acid, trimellitic anhydride, pyromellitic dianhydride, trimethylolpropane, glycerol, pentaerythritol, citric acid, tartaric acid, 3 -hydroxy glutaric acid or mixtures thereof. In another aspect, the branching agent comprises an epoxide, including, but not limited to, glycidyl methacrylate. In another aspect, the branching agent comprises a dendritic polymer having at least three reactive functional groups such as carboxylic acids, hydroxyl, or combinations thereof.

[0054] It has been found that other clear, semi-crystalline polymers can be mechanically oriented and / or thermally crystallized yet bound in crystal size by upper and lower boundary layers and yet are thermoformable when processed according to the methods described in the present disclosure. In addition to polyesters, other suitable crystalline and semi-crystalline polymers include polyamides, polyurethanes, polystyrene, polypropylene, cyclic olefin polymers, and copolymers (COP / COC), polyarylates, polycaprolactone, polylactic acid (PLA), and copolymers, combinations, and blends thereof.

[0055] While the use of recycled material may contain a small percentage of contamination, this contamination is of a low amount (less or equal to 2%) such that the required orientation level for packages made according to the current disclosure is often unaffected.Therefore, film and sheet utilizing either virgin-sourced resin or recycled content, or blends thereof, are suitable for the current disclosure.

[0056] The film or sheet utilized in the disclosure can be produced by a variety of methods. One method is extrusion which includes the traditional extrusion of a molten polymer extrudate through an optional coat hanger die with a three-roll cooling roll stack. Other suitable methods are film or sheet casting, also involving molten extrudate through a heated die, usually with a two-roll cooling stack where the film is optionally pinned to the cooling roll with an air knife or via electrical / static pinning methods. The film or sheet could alternatively be made via blown film extrusion where the molten extrudate is pushed through an annular die, often with cooling air forced through the center of the film tube, often without any cooling rolls being present. Some degree of pre-stretching can occur during the blown film extrusion process.

[0057] Besides extrusion, a film or sheet suitable for use in this disclosure could also be made via a calendering process. This method is not preferred due to the crystalline or semicrystalline nature of the polymer in use without the use of additives or modifiers to slow or prevent the crystallization induced during the process.

[0058] Once the film is produced, it can optionally be partially oriented. The methods of partial orientation suitable for certain aspects of this disclosure include both in-line and off-line or secondary processes. In-line orientation methods include traditional machine-direction orientation (MDO), transverse-direction orientation (TDO), diagonal-direction orientation (DDO), and orientation in both directions (bi-axially oriented film or sheet). Secondary processes involve batch-type stretching or tenter frames, or thermoforming machines that have pre- stretching capabilities built into the design. Such thermoforming machines could optionally utilize PET film or sheet made from the traditional manner with no pre-stretching involved, prior to the pre-stretching that occurs on the thermoforming machine just before thermoforming the now stretched film or sheet into a three-dimensional article.

[0059] In another aspect of the present disclosure, the multi-step process of orienting the package enhances the toughness. Articles made according to the prescribed procedure have higher energy at maximum load value than the amorphous, non-oriented packages when tested according to ASTM D3763 or the Bruceton staircase method.

[0060] Similarly, in another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier, optionally coupled with thermoforming and heat setting / crystallization activation, enhances the toughness. Articles made according to the prescribed procedure have higher energy at maximum load value than the amorphous, non-oriented packages when tested according to ASTM D3763 or the Bruceton staircase method.

[0061] In another aspect of the present disclosure, the multi-step process of orienting the package enhances the strength. Articles made according to the prescribed procedure have higher tear force than the amorphous, non-oriented packages when tested according to Elmendorf Tear Resistance testing, ASTM D1922 or Trouser Tear Resistance @ 200 mm / min, ISO 6383-1). Similarly, testing of non-oriented APET sheets exhibited a tensile strength at the yield point of about 8,200 psi whereas oriented APET tested at approximately 25,000 psi, over a 200% improvement.

[0062] Similarly, in another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier, optionally coupled with thermoforming and heat setting / crystallization activation, enhances the strength. Articles made according to the prescribed procedure have higher tear force than the amorphous, non-oriented packages when testedaccording to Elmendorf Tear Resistance testing, ASTM DI 922 or Trouser Tear Resistance @ 200 mm / min, ISO 6383-1).

[0063] In another aspect of the present disclosure, the multi-step process of orienting the package increases the tensile and flexural moduli according to ASTM D638 and ASTM D790, respectively. Specifically, testing of non-oriented APET sheets exhibited a tensile modulus of about 320,000 psi whereas oriented APET tested at approximately 720,000 psi, an improvement of over two times. This feature, when coupled with the increased toughness, leads to the ability to downgauge the product without sacrificing toughness and package sterility. Downgauging, when utilized, can lead to several improvements such as lower package weight (material and shipping advantages) and faster thermoforming cycle times (lower energy per part produced). Similarly, in another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier unit, optionally coupled with thermoforming and heat setting / crystallization activation, increases the tensile and flexural moduli according to ASTM D638 and ASTM D790, respectively. This feature, when coupled with the increased toughness, leads to the ability to downgauge the product without sacrificing toughness and package sterility. Downgauging, when utilized, can lead to several improvements such as lower package weight (material and shipping advantages) and faster thermoforming cycle times (lower energy per part produced).

[0064] In another aspect of the present disclosure, the multi-step process of orienting the package improves the barrier properties by slowing the vapor transmission rate. Testing of the nonoriented APET sheet exhibited a moisture vapor transmission rate of about 4.0 (g / 100in2*24h) versus 2.0 for the oriented APET sample. Oxygen Permeability was likewise 13 and 5 (cm3,mil / 100in2,24h*atm), respectively.

[0065] In another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier unit improves the barrier properties by slowing the vapor transmission rate. Testing of the non-oriented APET sheet exhibited a moisture vapor transmission rate of about 4.0 (g / 100in2,24h) versus 2.0 for the layered APET sample. Oxygen Permeability was likewise 13 and 5 (cm3,mil / 100in2*24h*atm), respectively.

[0066] In another aspect of the present disclosure, the multi-step process of orienting the package improves the chemical resistance. This feature is believed to occur from the reduced chemical permeability from oriented polymer chains and an increase in the fraction of impermeable pseudo crystals or spherulites. Such spherulites represent impermeable barriers for which chemical migration, through random diffusion mechanisms, must move around for deeper penetration into the article. Traditional packaging made from amorphous PET or PETG both can experience situations where a damp ethanol cloth, for example, is used to clean the package. In certain situations, this ethanol exposure can cause a chemical attack which may manifest itself as microcracks in the package. These microcracks weaken the package and cause concern for sterility retention.

[0067] Similarly, in another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation, improves the chemical resistance. This feature is believed to occur from the reduced chemical permeability from oriented polymer chains and an increase in the fraction of impermeable pseudo crystals or spherulites. Such spherulites represent impermeable barriers for which chemical migration, through random diffusion mechanisms, must move around for deeper penetration into the article. Note the chemical resistance is most improved wherein the external layer in which the chemical first contacts are made from the semi-crystalline layer.Traditional packaging made from amorphous PET or PETG both can experience situations where a damp ethanol cloth, for example, is used to clean the package. In certain situations, this ethanol exposure can cause a chemical attack which may manifest itself as microcracks in the package. These microcracks weaken the package and cause concern for sterility retention.

[0068] In another aspect of the present disclosure, the multi-step process of orienting the package improves the Q10 factor where the package physically ages during sterilization at a slower rate. Traditional packaging made from amorphous PET or PETG both undergo physical polymeric aging where toughness decreases as densification increases from molecular rearrangement, leading to a decrease in total free volume. One skilled in the art would understand that the propensity for crack propagation, leading to package failure, increases as total free volume decreases. The multi- step stretching process in the current disclosure, leading to pseudo crystals or spherulites, acts similarly to a low-density cross-link, slowing polymer chain rearrangement and thus improved physical aging as measured by ASTM Fl 980-02. Additionally, it should be noted that densification or physical aging increases as the delta or difference between the “room” temperature and the material’s glass transition decreases. The room temperature is herein defined as the environment in which the article or package is maintained. However, physical aging is reset where a package or article’s effective age becomes essentially zero when the room temperature exceeds the material’s glass transition temperature. For those skilled in the art, it would therefore be a goal to have a package exceed its glass transition temperature so that an effective zero age, and therefore the highest attainable toughness, is maintained. However, since amorphous articles also warp and sag under this condition, this process cannot be completed on amorphous PET or PETG since the package would be ruined. In contrast, under the present art, the oriented and heat set package can experience a temperature above the material’s glass transition temperature because the pseudocrystals or spherulites essentially hold the package together with minimal or non-existent warpages. In summary, in one embodiment of the current disclosure, the room temperature is preferred to exceed the material’s glass transition temperature because the amorphous sections of the article or package, around the pseudo crystals or spherulites, have an effective age that is reset to zero. Packages made according to the current disclosure have improved Q10 factors and age slower versus their amorphous counterparts because of both the restricted molecular rearrangement and due to the resetting of the effective ago to zero of the amorphous sections around the pseudo crystals or spherulites. The Q 10 factor for amorphous PET and APET thermoformed trays for rigid medical packaging has historically been measured at approximately 10. When manufactured according to the methods discussed in the current disclosure, the Q10 aging factor for these configurations was measurably improved, calculated to be between circa 6 to 8.5 with limited data.

[0069] In another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation, improves the Q10 factor of the overall film or sheet as a whole where the package physically ages during sterilization at a slower rate. Traditional packaging made from amorphous PET or PETG both undergo physical polymeric aging where toughness decreases as densification increases from molecular rearrangement, leading to a decrease in total free volume. One skilled in the art would understand that the propensity for crack propagation, leading to package failure, generally increases as total free volume decreases. The multi-step process of producing many layers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation of the current disclosure, leading to pseudo crystals or spherulites in its respective layer, acts similarly to a low-density cross-link, slowing polymer chain rearrangement and thus improved physical aging as measured by ASTM Fl 980-02. Additionally,it should be noted that densification or physical aging increases as the delta or difference between the “room” temperature and the material’s glass transition decreases. The room temperature is herein defined as the environment in which the article or package is maintained. However, physical aging is reset where a package or article’s effective age becomes essentially zero when the room temperature exceeds the material’s glass transition temperature. For those skilled in the art, it would therefore be a goal to have a package exceed its glass transition temperature so that an effective zero age, and therefore the highest attainable toughness, is maintained. However, since amorphous articles also warp and sag under this condition, this process cannot be completed on amorphous PET or PETG since the package would be ruined. In contrast, under the present art, the multi-step process of producing many layers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation, can experience a temperature above the material’s glass transition temperature because the pseudo crystals or spherulites essentially hold the package together with minimal or non-existent warpage. For example, the spherulites in the PET layer would help hold the package together even though the modulus of the PETG layer has dropped significantly because the glass transition temperature of the PETG layer has been exceeded. In summary, in one embodiment of the current disclosure, the room temperature is preferred to exceed the material’s glass transition temperature because the amorphous sections of the article or package, around the pseudo crystals or spherulites, and the PETG layers, have an effective age that is reset to zero. Packages made according to the current disclosure have improved Q10 factors and age slower versus their amorphous counterparts because of both the restricted molecular rearrangement in the semi-crystalline layer and due to the resetting of the effective ago to zero of the amorphous sections around the pseudo crystals or spherulites and in the PETG layer. One skilled in the art could substitute PET and PETG in the example above with other amorphousand semi-crystalline examples, and further could add C or D layers while still practicing the current disclosure.

[0070] In aspects of the present disclosure, the properties of the resulting article are improved and decay or change over time (“age”) more slowly versus articles made in the traditional, non-oriented, amorphous methods. Such properties include the relaxation modulus, the creep modulus, the storage modulus, the reduced storage modulus, creep compliance, reduced creep compliance, loss modulus, and complex modulus. One applicable testing equipment is DMA for another embodiment.

[0071] In aspects of the present disclosure, the properties of the resulting article are improved and decay or change over time (“age”) more slowly versus articles made in the traditional, non-oriented, amorphous methods. Such properties include the tensile modulus, tensile force, tensile elongation, tensile stress, and tensile strain.

[0072] In another aspect of the present disclosure, the multi-step process of orienting the package lessens undesirable webbing that might occur during thermoforming. Webbing occurs when a material stretches excessively during the thermoforming process. Several different factors can be involved, including excessive heat in the localized zone which facilitates excessive stretching in the localized area, allowing the rubbery film to fold on itself, causing a part defect. In the present disclosure, if the partially-stretched film has not been heat set to remove the internal stresses, the sheet can temporarily shrink and pull tight in the clamps right before and during thermoforming, thus lessening, at least temporarily, the propensity to form undesirable webbing.

[0073] Similarly, in another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation, lessens undesirable webbing that might occur duringthermoforming. Webbing occurs when a material stretches excessively during the thermoforming process. Several different factors can be involved, including excessive heat in the localized zone which facilitates excessive stretching in the localized area, allowing the rubbery film to fold on itself. In the present disclosure, if the partially-stretched film has not been heat set to remove the internal stresses, the sheet can temporarily shrink and pull tight in the clamps right before and during thermoforming, thus lessening the propensity to form undesirable webbing.

[0074] In aspects of the present disclosure, the multi-step process of orienting the package leads to differences in the degree of polymer chain alignment in different directions. This birefringence is quantifiable by evaluating the ratio or difference of the refractive index when measured in the film planar vs thickness directions.

[0075] Similarly, in another aspect of the present disclosure, the multi-step process of producing many layers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation, leads to differences in the degree of polymer chain alignment in different directions. This birefringence is quantifiable by evaluating the ratio or difference of the refractive index when measured in the film planar vs thickness directions.

[0076] In embodiments of the present disclosure, the difference in the refractive indices of the thermoplastic polymers in designated layer A versus designated layer B, adjacent layers, is less than 0.03 to minimize reflection and light bending that might otherwise cause the reflection or transmission of visible color and visible color flop, which often changes with the viewing angle.

[0077] In another aspect of the present disclosure, the multi-step process of orienting the package raises the article or package’s temperature stability. Partially orienting or partially stretching the substrate to form the package can mechanically induce small pseudo-crystals. These small crystallites increase the package’s temperature stability such that the material’s usetemperature can and preferably does exceed the material’s glass transition temperature. Part shrinkage from elevated thermal climates, including steam sterilization, is avoided or reduced when an optional heat setting step is involved.

[0078] In another aspect of the present disclosure, the multi-step process of producing many layers or microlayers via a multiplier element, optionally coupled with thermoforming and heat setting / crystallization activation, raises the article or package’s temperature stability. Thermal treatment of the many layered packages post thermoforming can thermally-induce small pseudocrystals. These small crystallites increase the package’s temperature stability such that the material’s use temperature can and preferably does exceed the material’s glass transition temperature. Part shrinkage from elevated thermal climates, including steam sterilization, is avoided or reduced when a heat setting step is involved. Typically, the elevated climate will be above room temperature, and more typically at least equal to the lowest glass transition temperature of any thermoplastic polymer used in the article to produce the microlayers. Additionally, the elevated climate will generally be up to the heat-setting temperature, but not to exceed the thermoplastic polymer’s melt temperature, especially any thermoplastic polymer that is crystalized or semi-crystalized in the article. Generally, temperatures above the heat-setting temperature can induce shrinkage and / or warpage, which are typically undesirable.

[0079] In one aspect of the current disclosure, traditionally manufactured PET, APET, and PETG trays, all of which maintain an amorphous morphology, have been found to fail certain PET recycle flake clumping test methods due to a high degree of agglomeration. When manufactured according to the methods discussed in the current disclosure, the PET and APET trays with small spherulites pass these test methods without agglomerations which otherwise are detrimental to thePET flake recycling process. One such test method is PET-S-08 issued by The Association ofPlastic Recyclers, when the optional crystallization protocol is not performed.

[0080] The above method, its steps, and systems incorporating the method can be better understood by the following prophetic examples, which illustrate the process. Physical experiments have been performed to demonstrate this novel technology. However, such testing has not been completed, and thus, there are gaps in the data sets actually run. Further experiments are still progressing at the time of the filing of this application. To better avoid confusion, all experiments will be described as prophetic whereas partial work has been performed. Where necessary, the prophetic examples are extrapolated from actual experiments carried out; though the inventors do not assert that the following prophetic examples themselves were carried out. The prophetic examples are offered by way of illustration of the process and are not meant to be limiting; rather, the scope is defined by the claims.PROPHETIC EXAMPLES

[0081] Example 1 (prophetic):

[0082] PETG copolyester grade 7870 is dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 268.3 degrees Celsius (515 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This flake is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 50 / 50 by mass. This molten stream then encounters a series of 10 multiplier segment stream splitters to form a microlayer thickness of approximately 372 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150 degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour.

[0083] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 32 seconds to reach a surface temperature of about 154.4 degrees Celsius (310 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three- dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with no significant degree of visible shrinkage, and it remains tough and generally clear with only a slight degree of a mirror-reflection effect. This part is deemed as being fit for use for steam sterilization as rigid medical packaging.

[0084] Example 2 (prophetic):

[0085] PETG copolyester grade 7870 is dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch singlescrew, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 268.3 degrees Celsius (515 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This flake is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a coextrusion block to form molten polymer stream AB with an approximate ratio of 65 / 35 by mass. This molten stream then encounters a series of 9 multiplier segment stream splitters to form a microlayer thickness of approximately 521 nanometers for microlayer B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150 degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour. This film is then re-heated to 90 degrees Celsius in a Bruckner tenter frame with a pull rate of about 3 inches per second in a bi-axial manner with a stretch ratio of about 1 .4. The final B layer thickness is about 260 nanometers, and the total film thickness was 0.015 inches.

[0086] The above film is then cut into an 8-inch length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 15 seconds to reach asurface temperature of about 154.4 degrees Celsius (310 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum with a plug assist on a male aluminum mold with 1-inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three-dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with subjectively a minor amount of visible shrinkage, and it remains tough and generally clear with only a slight degree of a mirrorreflection effect. This part is deemed as being fit for use for steam sterilization as rigid medical packaging.

[0087] Example 3 (prophetic, comparative):

[0088] PETG copolyester grade 7870 is dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch singlescrew, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 268.3 degrees Celsius (515 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This flake is then extruded on a 2-inch singlescrew, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a coextrusion block to form molten polymer stream AB with an approximate ratio of 50 / 50 by mass. This molten stream then encountered a series of 6 multiplier segment stream splitters to form amicrolayer thickness of approximately 5953 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150 degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour.

[0089] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 32 seconds to reach a surface temperature of about 154.4 degrees Celsius (310 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three- dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article was placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with only a minor degree of visible shrinkage, but it is brittle and sufficiently hazy to be deemed as not fit for use for steam sterilization as rigid medical packaging. The root cause for the failure is that the APET layer thickness was too thick at 5953 nanometers to physically limit crystal growth to below the wavelength of light, leading to opacity and brittleness.

[0090] Example 4 (prophetic):

[0091] Estane thermoplastic polyurethane is dried for 4 hours in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 98.9 degrees Celsius (210 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 237.8 degrees Celsius (460 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This flake is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 50 / 50 by mass. Due to the viscosity mismatch, a crescent-shaped coextrusion plug is used to physically push the material to achieve near uniform layer distribution of layer A versus layer B. This molten stream then encounters a series of 11 multiplier segment stream splitters to form a microlayer thickness of approximately 186 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150 degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour. The middle roll was polished chrome whereas the top roll was Teflon coated in order to prevent possible TPU layer adhesion.

[0092] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 32 seconds to reach a surfacetemperature of about 154.4 degrees Celsius (310 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three- dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted but some disturbance is noted in the surface polish, likely from the viscosity mismatch. The article is then heat set and crystallization completed by placing the part on a mold heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with some minor shrinkage, and it remains tough with some haze. This part might be deemed as being fit for use for steam sterilization as rigid medical packaging.

[0093] Example 5 (prophetic):

[0094] Tritan MP100 PCTM is dried for 6 hours in a Conair D400 desiccant dryer with -30 degrees Celsius dew point at 87.8 degrees Celsius (190 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 271.1 degrees Celsius (520 degrees Fahrenheit). Simultaneously, Ecdel 9966 PCCE resin is dried for 4 hours in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 65.6 degrees Celsius (150 degrees Fahrenheit). This resin is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 232.2 degrees Celsius (450 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 70 / 30 by mass. Due to the viscosity mismatch, a crescentshaped coextrusion plug is used to physically push the material to achieve near uniform layer distribution of layer A versus layer B . This molten stream then encounters a series of 10 multipliersegment stream splitters to form a microlayer thickness of approximately 223 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 79.4 degrees Celsius, and 57.2 degrees Celsius (70 degrees Fahrenheit, 175 degrees Fahrenheit, and 135 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour. The middle roll is polished chrome whereas the top roll was Teflon coated in order to prevent potential PCCE layer adhesion.

[0095] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 32 seconds to reach a surface temperature of about 182.2 degrees Celsius (360 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three- dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted but with some noticeable extrusion abnormalities. Extrusion optimization and other processing parameters require fine-tuning. The article is then heat set and crystallization completed by placing the part on a mold that is heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with some degree of visible shrinkage, and it remains tough with some visible haze that might be acceptable for some applications as rigid medical packaging.

[0096] Example 6 (prophetic):

[0097] Makrolon polycarbonate grade 2407 is dried for 8 hours in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 121.1 degrees Celsius (250 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 293.2 degrees Celsius (560 degrees Fahrenheit). Simultaneously, PCTA grade 13319 resin is also dried for 12 hours in a Conair D400 desiccant dryer with -30 degrees Celsius dew point at 121. degrees Celsius (250 degrees Fahrenheit). This resin is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 304.4 degrees Celsius (580 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 50 / 50 by mass. This molten stream then encounters a series of 10 multiplier segment stream splitters to form a microlayer thickness of approximately 372 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 60 degrees Celsius, 87.8 degrees Celsius, and 93.3 degrees Celsius (140 degrees Fahrenheit, 190 degrees Fahrenheit, and 200 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour.

[0098] The above film is then cut into a 1-foot length square, dried in the aforementioned desiccant dryer at 71.1 degrees Celsius (160 degrees Fahrenheit overnight, and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 44 seconds to reach a surface temperature of about 204.4 degrees Celsius (400 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1- inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet intoa three-dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with no significant degree of visible shrinkage, and it remains tough and generally clear with only a slight degree of a mirror-reflection effect. This part is deemed as being fit for use for steam sterilization as rigid medical packaging.

[0099] Example 7 (prophetic):

[0100] PCTA copolyester grade CN005 is dried for 8 hours in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 73.9 degrees Celsius (165 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 254.4 degrees Celsius (490 degrees Fahrenheit). Simultaneously, Tritan PCTM grade SC900 is also dried for 6 hours in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 121.1 degrees Celsius (250 degrees Fahrenheit). This resin is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 278.8 degrees Celsius (550 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 50 / 50 by mass. This molten stream then encountered a series of 11 multiplier segment stream splitters to form a microlayer thickness of approximately 186 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures were 21.1 degrees Celsius, 79.4 degrees Celsius, and 87.8 degreesCelsius (70 degrees Fahrenheit, 175 degrees Fahrenheit, and 190 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour.

[0101] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 39 seconds to reach a surface temperature of about 176.7 degrees Celsius (350 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three- dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with no significant degree of visible shrinkage, and it remains tough and generally clear with only a slight degree of a mirror-reflection effect. This part is deemed as being fit for use for steam sterilization as rigid medical packaging.

[0102] Example 8 (prophetic):

[0103] PETG copolyester grade 7870 is dried for 8 hours in a Conair D400 desiccant dryer with -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24:1 Crown extrusion line using a straight temperature profile of 248.9 degrees Celsius (480 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 73.9 degrees Celsius (165 degrees Fahrenheit). This flake is then extruded on a2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit),herein designated as layer B. Simultaneously, PETM copolyester grade DX4000 was also dried for 12 hours in a Conair D400 desiccant dryer with -30 degrees Celsius dew point at 82.2 degrees Celsius (180 degrees Fahrenheit). This resin is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer C. Layer B is split in the coextrusion block prior to joining the other streams. These three streams are joined in a co-extrusion block to form molten polymer stream ABCB with an approximate ratio of 33 / 16 / 34 / 16 by mass. This molten stream then encounters a series of 8 multiplier segment stream splitters to form a microlayer thickness of approximately 245 nanometers for each microlayer A and B when measuring the final film thickness of 0.015 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150 degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour.

[0104] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 18 seconds to reach a surface temperature of about 168.3 degrees Celsius (335 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three- dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resultingpart survives steam sterilization with no significant degree of visible shrinkage, and it remains tough and generally clear with only a slight degree of a mirror-reflection effect. This part is deemed as being fit for use for steam sterilization as rigid medical packaging.

[0105] Example 9 (prophetic, comparative):

[0106] Tritan MP 100 PCTM is dried for 6 hours in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 87.8 degrees Celsius (190 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 271.1 degrees Celsius (520 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This flake is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 10 / 90 by mass. This molten stream then encounters a series of 18 multiplier segment stream splitters to form a microlayer thickness of less than 20 nanometers for microlayer A when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150 degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour. The film is not thermoformed nor is any other processing performed because the film is excessively hazy and not fit-for-use for medical packaging. Subsequent photomicrograph analysis on a scanning electron microscope (SEM)shows that layer A does not exist as discrete microlayers because the microlayers were split too many times, becoming too thin, resulting in domains of Tritan MP 100 PCTM in an APET rich environment. In other words, an operating line exists where a certain combination of multiplier units and the ratio of polymer layers (10 / 90 in this example) becomes too thin to maintain discrete microlayers, resulting in the breakup of the microlayer into discrete domain regions.

[0107] Example 10 (prophetic):

[0108] Sustainable PEF resin, as touted by Avantium, is dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 126.6 degrees Celsius (260 degrees Fahrenheit). This resin, herein designated as layer A, is then extruded on a 4.5-inch single screw, non-vented, 24: 1 Crown extrusion line using a straight temperature profile of 268.3 degrees Celsius (515 degrees Fahrenheit). Simultaneously, APET recycle flake is also dried overnight (approximately 24 hours) in a Conair D400 desiccant dryer with a -30 degrees Celsius dew point at 62.8 degrees Celsius (145 degrees Fahrenheit). This flake is then extruded on a 2-inch single screw, non-vented, satellite extruder using a straight temperature profile of 276.7 degrees Celsius (530 degrees Fahrenheit), herein designated as layer B. These two streams are joined in a co-extrusion block to form molten polymer stream AB with an approximate ratio of 50 / 50 by mass. This molten stream then encounters a series of 10 multiplier segment stream splitters to form a microlayer thickness of approximately 372 nanometers for each microlayer A and B when measuring the final film thickness of 0.030 inches. The extrudate is deposited onto a three-roll, water-cooled calendar stack, with downward orientation, using chrome polished rolls with a polished surface finish of about zero microinches Ra when new. Roll temperatures are 21.1 degrees Celsius, 65.6 degrees Celsius, and 71.1 degrees Celsius (70 degrees Fahrenheit, 150degrees Fahrenheit, and 160 degrees Fahrenheit) from the top to bottom rolls at a production rate of about 150 pounds per hour.

[0109] The above film is then cut into a 1-foot length square and thermoformed at an oven temperature of 398.9 degrees Celsius (750 degrees Fahrenheit) for 32 seconds to reach a surface temperature of about 154.4 degrees Celsius (310 degrees Fahrenheit) with the B layer facing the mold. The sheet is thermoformed using a vacuum with a plug assist on a male aluminum mold with 1 -inch-deep cylinders with subsequent air cooling from a fan (30 seconds) to turn the flat sheet into a three-dimensional article. The above article is then removed and inspected, showing that the proper shape was imparted. The article is then heat set and crystallization completed by placing the part on a mold that was heated to 150 degrees Celsius for 10 minutes. Upon cooling, the article is placed in an autoclave steam sterilization unit for 10 minutes at 121 degrees Celsius. The resulting part survives steam sterilization with no significant degree of visible shrinkage, and it remains tough and generally clear with only a slight degree of a mirror-reflection effect. This part is deemed as being fit for use for steam sterilization as rigid medical packaging. Note the use of two crystallizable resins in the same article which become an effective boundary layer for one another.

[0110] The method and compositions of this disclosure can be further understood by the following numbered embodiments.

[0111] Embodiment 1: A process for producing a clear, three-dimensional article, said process comprising:(a) extruding a first amorphous, molten stream of a first thermoplastic polymer that is crystallizable;(b) extruding a second amorphous, molten stream of a second thermoplastic polymer;(c) joining the first and second amorphous, molten streams in a co-extrusion block to form a first layered amorphous, molten stream with two layers wherein the two layers remain distinct without interlayer mixing, even in the molten state;(d) subjecting the first layered amorphous, molten stream to a multiplier element to form a second layered amorphous, molten stream having twice the layers of the first amorphous, molten stream;(e) subjecting the second layered amorphous, molten stream to a plurality of multiplier elements, oriented in series fashion, to form a many -layered polymer stream with a minimum quantity of at least 80, distinct microlayers in the manylayered polymer stream;(f) spreading and cooling the many-layered polymer stream into an amorphous film or sheet with an average overall thickness of at least 0.010 inches but not more than 0.500 inches, wherein a sufficient quantity of multiplier elements is used such that the thickness of each microlayer containing the first thermoplastic polymer has a maximum thickness of 2000 nanometers upon cooling;(g) forming a three-dimensional article after step (e) by using a mold;(h) heat-setting and crystallizing the layers of the thermoplastic polymer while the three-dimensional article remains on a mold, wherein the resulting heat-set three- dimensional article can withstand long-term exposure to an elevated thermal climate that is at least equal to the lower of the first thermoplastic polymer’s glass transition temperature and the second thermoplastic polymer’s glass transitiontemperature, up to the heat-setting temperature, but not to exceed the first thermoplastic polymer’s melt temperature, wherein the heat-set three-dimensional article, post thermal climate exposure, does not exhibit a significant degree of warpage and is without a significant degree of visual haze generation in a majority of the heat-set three-dimensional article, and optionally the three-dimensional article has a haze value of less than 10% (or less than 8%) as measured by ASTM D1003 and / or a measured light transmission of greater than 70% (or greater than 75%) as measured by ASTM DI 003.

[0112] Embodiment 2: The process of Embodiment 1, further comprising coextruding one or more additional amorphous, molten streams of differing thermoplastic polymers such that prior to step (d) the first, second and additional amorphous, molten streams are joined to produce from 3 to 12 layers in the first layered amorphous, molten stream prior to being subjected to the multiplier elements.

[0113] Embodiment 3: The process of either Embodiments 1 or 2, wherein at least one of the first amorphous, molten stream and the second amorphous, molten stream is split in the co-extrusion block prior to being joined with the other amorphous, molten polymer stream.

[0114] Embodiment 4: The process of any proceeding Embodiment, wherein the elevated thermal climate is achieved via steam sterilization where the steam is initially applied to the external surface of the heat-set three-dimensional article.

[0115] Embodiment 5: The process of any proceeding Embodiment, wherein the elevated thermal climate is achieved via steam sterilization that occurs from 215 to 430 degreesFahrenheit (101 to 221 degrees Celsius) for at least 10 seconds.

[0116] Embodiment 6: The process of any proceeding Embodiment, wherein the fdm or sheet is partially stretched prior to the forming step (g) to form a partially-stretched fdm or sheet in which the layers formed from the first thermoplastic polymer become partially-crystallized layers, and wherein the film or sheet is partially stretched with an in-line process, such as machinedirection orientation (MDO) stretching, transverse-direction orientation (TDO) stretching, stretched via a diagonal direction orientation (DDO) stretching process, stretched bi-axially (both directions, simultaneously as an option), or stretched via blown film extrusion.

[0117] Embodiment 7: The process of Embodiment 6, wherein the film or sheet produced in step (f) has an original length and the elongation during the partial stretching is less than 3.5 times the original length but more than 1.2 times the original length.

[0118] Embodiment 8: The process of Embodiment 7, wherein the thickness of each of the partially-crystalline layers remain below 1000 nanometers in thickness from both the partial stretching and the subjecting to the multiplier elements in steps (d) and (e).

[0119] Embodiment 9: The process of Embodiment 6, wherein the film or sheet is partially stretched with an off-line, optionally batch-wise process, post-extrusion, process for machine-direction orientation (MDO) stretching, transverse-direction orientation (TDO) stretching, stretched via a diagonal direction orientation (DDO) stretching process, stretched bi- axially (both directions, simultaneously as an option), or stretched via blown film extrusion.

[0120] Embodiment 10: The process of any proceeding Embodiment, wherein the partially-stretched film or sheet is turned into a three-dimensional article via vacuum thermoforming with optional plug assist, drape forming, pressure forming (including pressurized air), matched-mold pressing or membrane pressing with optionally hot or cold bladder hydraulics as is often used in making membrane switches.

[0121] Embodiment 11 : The process of any of Embodiment 6 to 10, wherein the number of multiplier elements used results in an average microlayer thickness below 350 nanometers for the partially-crystalized layers.

[0122] Embodiment 12: The process of any proceeding Embodiment, wherein the clear, three-dimensional article is heat set and further crystallized by placing or keeping the article on the mold, during forming or optionally in a separate step, and subjecting said article to a temperature between the lowest glass transition temperature of the first or second thermoplastic polymer and the melt temperature of the first thermoplastic polymer for at least 5 seconds.

[0123] Embodiment 13 : The process of Embodiment 12, wherein the heat setting, and further crystallization occur between 105 degrees Celsius and 235 degrees Celsius.

[0124] Embodiment 14: A clear, three-dimensional article with a total thickness of0.010 inches to 0.150 inches containing at least a first thermoplastic polymer and a second thermoplastic polymer, wherein the first thermoplastic polymer is different from the second thermoplastic polymer, and wherein the first thermoplastic polymer is crystalline or semicrystalline, and wherein the article has a minimum of 80 microlayers each layer comprising one of the thermoplastic polymers so that a first portion of the layers are crystalline or semi-crystalline layers with a maximum layer thickness of 700 nanometers for each of the crystalline or semicrystalline layers, and wherein the crystalline or semi-crystalline layers have been thermally crystallized so that they can withstand long-term exposure to an elevated thermal climate, including steam sterilization.

[0125] Embodiment 15: A clear, three-dimensional article, made by a process comprising:(a) extruding a first molten stream of a first thermoplastic polymer that is crystallizable to a crystalline or partially crystalline state;(b) extruding a second molten stream of a second thermoplastic polymer;(c) combining the first molten stream and second molten streams in a co-extrusion block to form a first layered molten stream;(d) subjecting the first layered molten stream to a multiplier element to form a second layered molten stream having twice the layers of the first layered molten stream;(e) subjecting the four-layer molten stream to a plurality of multiplier elements, oriented in series fashion, to form a many-layered molten stream;(f) spreading and cooling the many-layered molten stream into a film or sheet with an average overall thickness of at least 0.010 inches but not more than 0.500 inches, wherein a sufficient quantity of multiplier elements is used such that the thickness of each individual layer containing the thermoplastic polymer that is crystallizable contains a maximum thickness of 2000 nanometers upon cooling;(h) forming a three-dimensional article after step (e) by using a mold;(i) optionally heat-setting and further crystalizing the first thermoplastic polymer while the three-dimensional article remains on a mold, wherein the resulting heat-set article can withstand long-term exposure to an elevated thermal climate that is at least equal to the lower of the first thermoplastic polymer’s glass transition temperature and the second thermoplastic polymer’s glass transitiontemperature, up to the heat-setting temperature, but not to exceed the first thermoplastic polymer’s melt temperature, wherein the article, post thermal climate exposure, does not exhibit a significant degree of warpage and is without a significant degree of visual haze generation in a majority of the article.

[0126] Embodiment 16: The article of either of Embodiments 14 or 15, wherein the first thermoplastic polymer and second thermoplastic polymer are selected from aromatic or aliphatic versions of polyesters, polyamides, polyurethanes, polystyrene, polypropylene, cyclic olefin polymers and copolymers (COP / COC), polyarylates (PAR), polycaprolactone (PCL), polylactic acid (PLA), and copolymers, combinations, and blends thereof.

[0127] Embodiment 17: The article of Embodiment 16, wherein the polyester can be either aromatic or aliphatic in nature and comprise, but are not limited to, polyethylene terephthalate (PET), amorphous polyethylene terephthalate (APET), glycol-modified polyethylene terephthalate (PETG), acid-modified polyethylene terephthalate (PETA), Polycyclohexylenedimethylene terephthalate (PCT), glycol-modifiedPolycyclohexylenedimethylene terephthalate (PCTG), acid-modifiedPolycyclohexylenedimethylene terephthalate (PCTA), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), Polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), Polybutylene Naphthalate (PBN), Polybutylene adipate-co-terephthalate (PBAT), Polytretramethylenecyclobutylene terephthalate (PCTM), Polycyclohexanedimethyl cyclohexanedicarboxylate (PCCD), Polycyclohexylene dimethylene cyclohexanedicarboxylate (PCCE, copolyester ether elastomer), Polycyclohexanedimethylene-co-isosorbide terephthalate, and copolymers, isomers and blends thereof.

[0128] Embodiment 18: The article of Embodiment 17, wherein the primary monomers and secondary diol or diacid comonomers and additional comonomers, including multifunctional branching monomers, can be either aromatic or aliphatic in nature and comprise the following moieties: propylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-l,3-diol, 2,2- dimethyl- 1,3 -propanediol, diethylene glycol, 2-ethyl-2-butyl-l,3-propanediol, 2-ethyl-2-isobutyl- 1,3-propanediol, 1,3 -butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6- hexanediol, 1,8-octanediol, 2,2,4-trimethyl-l,6-hexanediol, thiodi ethanol, 1,2- cyclohexanedimethanol, 1,3 -cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylylene glycol, polyethylene glycol, diethylene glycol, polytetramethylene glycol, 2,2,4,4-tetramethyl-l,3- cyclobutanediol, 2,5-hydroxymethyl tetrahydrofuran, phthalic acid, isophthalic acid, furandicarboxylic acid, 1,4-, 1,5-, 2,6-, and 2,7-naphthalenedicarboxylic acid, 1,3-, 1,4- cyclohexanedicarboxylic acid (which may be cis, trans or a mixture thereof), cyclohexanediacetic acid, trans-4,4'-stilbenedicarboxylic acid, 4,4'-oxydibenzoic acid, 3,3'- and 4, d'biphenyldicarboxylic acids, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, suberic acid, pimelic acid, nonane, decane, dodecanedicarboxylic acids, cyclohexane dimethanol, butanediol, propanediol, neopentyl glycol, spiroglycol, isosorbide, 2, 2, 4, 4 - tetramethyl-l,3-cyclobutanediol, diethylene glycol, ethylene glycol, bisphenol A (BPA), pentaerythritol and polyethylene glycol (PEG), and combinations thereof.

[0129] Embodiment 19: The article of any of Embodiments 14 to 18, wherein the second thermoplastic polymer is an amorphous polymer so that a second portion of the microlayers are amorphous layers.

[0130] Embodiment 20: The article of any of Embodiments 14 to 119, wherein the second thermoplastic polymer is crystallizable but with a different composition in either or both chemistry or intrinsic viscosities than the first thermoplastic polymer.

[0131] Embodiment 21 : The article of either Embodiment 14 or 15, wherein the first thermoplastic polymer is polyethylene terephthalate, and the second thermoplastic polymer is PETG.

[0132] Embodiment 22: The article of either Embodiment 14 or 15, wherein the first thermoplastic polymer is polyethylene terephthalate, and the second thermoplastic polymer is polyurethane.

[0133] Embodiment 23 : The article of Embodiment 22, wherein the polyurethane possesses scratch resistance properties that are improved versus polyethylene terephthalate.

[0134] Embodiment 24: The article of either Embodiment 14 or 15, wherein at least one of the first thermoplastic polymer and the second thermoplastic polymer comprise polycarbonate or polycarbonate blends.

[0135] Embodiment 25: The article of either Embodiment 14 or 15, wherein the difference in the refractive indices of the thermoplastic polymers in adjacent layers is less than 0.03 for improved colorless packaging, to minimize reflection and light bending that might otherwise cause the reflection or transmission of visible color or a mirroring effect.

[0136] Embodiment 26: The article of either Embodiment 14 or 15, wherein the clear, three-dimensional article is made from at least one hygroscopic polymeric material with a minimum moisture regain of at least 0.05%.

[0137] Embodiment 27: The article of either Embodiment 14 or 15, wherein the polymeric mass of the first thermoplastic polymer in the layers of the article after crystallization is between 15 to 85% of the total mass of the article.

[0138] Embodiment 28: The article of either Embodiment 14 or 15, wherein the first thermoplastic polymer and second thermoplastic polymer are miscible when melt blended together in a twin-screw extruder for improved recyclability, including the edge trim scrap.

[0139] Embodiment 29: The article of either Embodiment 14 or 15, wherein the difference in the thermodynamic Chi factor for blending the layersthe layer of the article is less than 0.01.

[0140] Embodiment 30: The article of any of Embodiments 14 to 29, wherein the clear, three-dimensional article has a measured haze value of less than 10% as measured by ASTM D1003.

[0141] Embodiment 31 : The article of any of Embodiments 14 to 30, wherein the clear, three-dimensional article has a measured light transmission of greater than 70% as measured by ASTM DI 003.

[0142] Embodiment 32: The article of any of Embodiments 14 to 31, wherein the first thermoplastic polymer and, if crystallizable, the second thermoplastic polymer has a percentage of crystallinity of at least 1.3% as measured by DSC, SALLS, or XRD in the resulting article.

[0143] Embodiment 33: The article of any of Embodiments 14 to 32, wherein the clear, three-dimensional article has a birefringence or refractive index difference of greater than 0.005 when measured along the plane of the film or sheet in the stretched direction versus the nonstretched direction.

[0144] Embodiment 34: The article of any of Embodiments 14 to 32, wherein the clear, three-dimensional article has a birefringence or refractive index difference of greater than 0.005 when measured along the plane of the film or sheet in the stretched direction versus the measurement taken through the film or sheet thickness direction.

[0145] Embodiment 35: The article of any of Embodiments 14 to 34, wherein the clarity of the three-dimensional article has been temporarily or permanently obscured by addition of a matte or engineered surface texture to at least one side of the film or sheet used to mold the article, wherein the film or sheet is clear.

[0146] Embodiment 36: The article of any of Embodiments 14 to 35, wherein the clear, three-dimensional article is at least as tough or strong as a similar article made from an amorphous, thermoplastic film or sheet with less than 1.3% crystallinity when tested according to Instrumented Impact Test ASTM D3763, the Bruceton staircase impact method, Elmendorf Tear Resistance testing, ASTM DI 922 or Trouser Tear Resistance @ 200 mm / min, ISO 6383-1).

[0147] Embodiment 37: The article of any of Embodiments 14 to 36, wherein the clear, three-dimensional article possesses a physical aging Q10 factor that is numerically lower than that measured from a similar article made from an amorphous, thermoplastic film or sheet with less than 1.3% crystallinity when tested according to ASTM F1980-02.

[0148] Embodiment 38: The article of any of Embodiments 14 to 37, wherein the heat-setting and crystallization completion reduces the article shrinkage to less than 15% of its original dimension post thermal climate exposure when measured by the change in volume via a liquid fill before versus after processing.

[0149] Embodiment 39: The article of any of Embodiments 14 to 38, wherein the chemical resistance of the article is improved compared to the amorphous, non-crystalized version of the article when tested according to ASTM D543.

[0150] Embodiment 40: The article of any of Embodiments 14 or 39, wherein at least one of the thermoplastic polymers is an amorphous polymer such that a second of the layers are amorphous layers, and wherein the presence of crystalline or semi-crystalline layers aid in holding the amorphous layers in place to prevent distortion when the entire article is exposed to an elevated thermal climate that is higher than the glass transition temperature of the amorphous layer or layers.

[0151] Embodiment 41 : The article of Embodiment 40, wherein the physical aging of the amorphous layer is essentially zero or unaged since the elevated thermal climate is higher than the glass transition temperature of the amorphous layer or layers.

[0152] Embodiment 42: The article of any of Embodiments 16, 17, 18, 21, or 22, wherein the polyester or PET is from a recycled source.

[0153] Embodiment 43 : A clear, three-dimensional article, optionally the article of any of claims 14 to 42, comprising a crystalline or semi-crystalline thermoplastic polymer with a crystallinity of at least 1.5% with a crystal size below 400 nanometers, haze less than 10% and light transmission greater than 70% that can withstand long-term exposure to elevated thermal climates up to 230 degrees Celsius wherein the article, post elevated thermal exposure, exhibits less than 10% shrinkage.

[0154] Embodiment 44: The article of Embodiment 14, 15, or 43, wherein the physical age of the article is essentially zero or unaged when the elevated thermal climate is higher than the glass transition temperature of the amorphous regions interlaced between the small spherulites.

[0155] Embodiment 45: The article of Embodiment 14, 15 or 43 wherein the sterilization process is steam sterilization.

[0156] Embodiment 46: The article of Embodiment 14, 15 or 43, wherein the sterilization process is ethylene oxide, gamma, e-beam or chemically-activated sterilization.

[0157] Embodiment 47: The process of Embodiment 1, wherein the physical age of the article is essentially zero or unaged when the elevated thermal climate is higher than the glass transition temperature of amorphous regions interlaced between small spherulites in the crystalline layers.

[0158] Embodiment 48: The process of Embodiment 1, wherein the sterilization process is steam sterilization.

[0159] Embodiment 49: The process of Embodiment 1, wherein the sterilization process is ethylene oxide, gamma, e-beam or chemically-activated sterilization.

[0160] Embodiment 50: The article according to any of Embodiments 14 to 46, wherein recycled flake ground from the article passes PET flake clumping tests, including certain protocols as defined in test method PET-S-08 issued by The Association of Plastic Recyclers.

[0161] Embodiment 51 : The article according to any of Embodiments 14 to 46, wherein the chemical composition of the final formed article, in aggregate, passes the requirements which classify the article as polyethylene terephthalate according to the state of California in Assembly Bill 906, including Section 18013.

[0162] Embodiment 52: The article of any of Embodiments 14 to 38, wherein the barrier properties of the article are improved compared to the amorphous, non-crystalized version of the article, including vapor transmission rate and oxygen permeability.

[0163] Therefore, the present compositions and methods are well adapted to attain the ends and advantages mentioned, as well as those inherent therein. The particular examples disclosed above are illustrative only, as the present methods may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative examples disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the present treatment additives and methods. While compositions and methods are described in terms of “comprising,” “containing,” “having,” or “including” various components or steps, the compositions and methods can also, in some examples, “consist essentially of’ or “consist of’ the various components and steps. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. Every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee.

Claims

What is claimed is:

1. A process for producing a clear, three-dimensional article, said process comprising:(a) extruding a first amorphous, molten stream of a first thermoplastic polymer that is crystallizable;(b) extruding a second amorphous, molten stream of a second thermoplastic polymer;(c) joining the first and second amorphous, molten polymer streams in a coextrusion block to form a first layered amorphous, molten stream with two layers wherein the two layers remain distinct without interlayer mixing, even in the molten state;(d) subjecting the two-layer amorphous, molten stream to a plurality of multiplier elements to form a many-layered polymer stream with a minimum quantity of at least 80 distinct microlayers in the many-layered molten polymer stream;(e) cooling the many-layered molten layers into an amorphous sheet with an average overall thickness of at least 0.010 inches but not more than 0.500 inches, wherein a sufficient quantity of multiplier elements is used such that the thickness of each microlayer containing the first thermoplastic polymer has a maximum thickness of 2000 nanometers upon cooling;(f) forming a three-dimensional article after step (e);(g) heat-setting at a heat-setting temperature and crystallizing the microlayers containing the first thermoplastic polymer, wherein the resulting heat-set three-dimensional article can withstand long-term exposure to an elevated thermal climate up to the heat-setting temperature, but not to exceed the melt temperature of the first thermoplastic polymer, and whereinthe three-dimensional article has an average haze value of less than 10% and retains an average haze value of less than 10% after thermal climate exposure.

2. The process of claim 1, further comprising extruding one or more additional amorphous, molten streams of differing thermoplastic polymers such that prior to step (d) the first, second, and additional amorphous, molten streams are joined to produce from 3 to 12 layers in the first layered amorphous, molten stream prior to being subjected to the multiplier elements.

3. The process of claim 1, wherein at least one of the first amorphous, molten stream and the second amorphous, molten stream is split in the co-extrusion block prior to being joined with the other amorphous, molten polymer stream.

4. The process of claim 1, wherein the elevated thermal climate is achieved via steam sterilization where the steam is initially applied to the external surface of the clear, three- dimensional article.

5. The process of claim 1, wherein the elevated thermal climate is achieved via steam sterilization that occurs from 101 to 221 degrees Celsius (215 to 430 degrees Fahrenheit) for at least 10 seconds.

6. The process of claim 1, wherein the sheet is partially stretched prior to the forming step to form a partially stretched sheet in which the layers formed from the first thermoplastic polymer become partially-crystallized layers.

7. The process of claim 6, wherein the sheet produced in step (e) has an original length and elongation during partial stretching is less than 3.5 times the original length but more than 1.2 times the original length.

8. The process of claim 7, wherein the thickness of the partially-crystalline layers remain below 1000 nanometers in thickness from both the partial stretching and the subjecting to the multiplier elements.

9. The process of claim 1, wherein the number of multiplier elements used results in an average microlayer thickness below 350 nanometers for each microlayer.

10. The process of claim 1, wherein the heat setting and crystallizing occur between 105 degrees Celsius and 235 degrees Celsius.

11. A clear, three-dimensional article formed from a sheet comprising at least a first thermoplastic polymer and a second thermoplastic polymer, wherein the sheet has a total thickness of 0.010 inches to 0.150 inches, the first thermoplastic polymer is different from the second thermoplastic polymer, the first thermoplastic polymer is crystalline or semi-crystalline, and the sheet has a minimum of 80 microlayers, and each microlayer formed from either the first thermoplastic polymer or the second thermoplastic polymer so that a first portion of the microlayers are crystalline or semi-crystalline layers with a maximum layer thickness of 700 nanometers.

12. The article of claim 11, wherein the crystalline or semi-crystalline layers have been thermally crystallized and can withstand long-term exposure to an elevated thermal climate, including steam sterilization.

13. The article of either claim 11 or claim 12, wherein the clear, thermoplastic, crystalline or semi-crystalline layer comprises aromatic or aliphatic versions of polyesters, polyamides, polyurethanes, polystyrene, polypropylene, cyclic olefin polymers and copolymers(COP / COC), polyarylates (PAR), Polycaprolactone (PCL), Polylactic acid (PLA), and copolymers, combinations, and blends thereof.

14. The article of claim 13, wherein the crystalline or semi-crystalline polyester can be either aromatic or aliphatic in nature and comprise, but are not limited to, polyethylene terephthalate (PET), amorphous polyethylene terephthalate (APET), glycol-modified polyethylene terephthalate (PETG), acid-modified polyethylene terephthalate (PETA), Polycyclohexylenedimethylene terephthalate (PCT), glycol-modifiedPolycyclohexylenedimethylene terephthalate (PCTG), acid-modifiedPolycyclohexylenedimethylene terephthalate (PCTA), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), Polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), Polybutylene Naphthalate (PBN), Polybutylene adipate-co-terephthalate (PBAT), , Polytretramethylenecyclobutylene terephthalate (PCTM), Poly cyclohexanedimethyl cyclohexanedicarboxylate (PCCD), Polycyclohexylene dimethylene cyclohexanedi carb oxy late (PCCE, copolyester ether elastomer), Polycyclohexanedimethylene-co-isosorbide terephthalate, and copolymers, isomers and blends thereof.

15. The article of claim 14, wherein the primary monomers and secondary diol or diacid comonomers and additional comonomers, including multi-functional branching monomers, can be either aromatic or aliphatic in nature and comprise the following moieties: propylene glycol, 1,3- propanediol, 2,4-dimethyl-2-ethylhexane-l,3-diol, 2, 2-dimethyl- 1,3 -propanediol, di ethylene glycol, 2-ethyl-2-butyl- 1,3 -propanediol, 2-ethyl-2-isobutyl-l,3-propanediol, 1,3-butanediol, 1,4- butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2,2,4-trimethyl-l,6- hexanediol, thiodiethanol, 1,2-cyclohexanedimethanol, 1,3 -cyclohexanedimethanol, 1,4- cyclohexanedimethanol, p-xylylene glycol, polyethylene glycol, diethylene glycol,polytetramethylene glycol, 2,2,4,4-tetramethyl-l,3-cyclobutanediol, 2,5-hydroxymethyl tetrahydrofuran, phthalic acid, isophthalic acid, furandicarboxylic acid, 1,4-, 1,5-, 2,6-, and 2,7- naphthalenedicarboxylic acid, 1,3-, 1,4-cyclohexanedicarboxylic acid (which may be cis, trans or a mixture thereof), cyclohexanediacetic acid, trans-4,4'-stilbenedicarboxylic acid, 4,4'- oxy dibenzoic acid, 3,3'- and 4,4'-biphenyldicarboxylic acids, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, suberic acid, pimelic acid, nonane, decane, dodecanedicarboxylic acids, cyclohexane dimethanol, butanediol, propanediol, neopentyl glycol, spiroglycol, isosorbide, 2, 2, 4, 4 - tetramethyl-l,3-cyclobutanediol, diethylene glycol, ethylene glycol, bisphenol A (BPA), pentaerythritol and polyethylene glycol (PEG), and combinations thereof.

16. The article of either claim 11 or claim 12, wherein the second thermoplastic polymer is an amorphous polymer so that a second portion of the microlayers are amorphous layers.

17. The article of either claim 11 or claim 12, wherein the second thermoplastic polymer is crystallizable but with a different composition in chemistry or intrinsic viscosities than the first thermoplastic polymer.

18. The article of either claim 11 or claim 12, wherein the difference in the refractive indices of the thermoplastic polymers in adjacent microlayers is less than 0.03.

19. The article of either claim 11 or claim 12, wherein the clear, three-dimensional article has a measured haze value of less than 10% as measured by ASTM DI 003.

20. The article of either claim 11 or claim 12, wherein the clear, three-dimensional article has a measured light transmission of greater than 70% as measured by ASTM DI 003.