WO2012178104A1 - Method of making pet preforms - Google Patents

Abstract

The present invention is directed to methods, devices and systems for making polymer preforms having a controlled amount of stress and molecular orientation, as well as to the polymer preforms formed thereby. The present invention also extends to methods for making polymer containers from such polymer preforms, as well as to the polymer containers formed thereby and packaged beverages comprising such containers. Advantageously, the polymer containers of the present invention offer improved performance, including but not limited to extended shelf-life.

Description

METHOD OF MAKING PET PREFORMS

CLAIM OF PRIORITY

[0001] This application claims priority under 35 U.S.C. § 1 19 to United States

Provisional Patent Application Serial Number 61/499835, titled "Molecular Level Orientation of PET Preforms" and filed on June 22, 201 1, the entire contents of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a method, device and system for making polymer preforms having a controlled amount of stress and molecular orientation, as well as to polymer preforms and containers formed from such polymer preforms.

BACKGROUND OF THE INVENTION

[0003] Polyethylene terepthalate and its co-polyesters (hereinafter referred to collectively as "PET") are widely used for making containers such as bottles for various packaged beverages including carbonated beverages, juice, and water. PET has an excellent combination of clarity, mechanical properties, and gas barrier properties, but these properties can be improved.

[0004] The vast majority of PET bottles are made according to a two-step process known as injection stretch blow molding. In the first step, a molten crystallizable PET resin is introduced into a mold cavity having the shape of the desired preform. Upon cooling, the molten polymer material produces a solid preform. In the second step, the preform is heated rapidly and then inflated against a two-part mold to form it into the final shape of the PET bottle.

[0005] On a molecular level, a polymer sample can be either amorphous or semi- crystalline. An amorphous polymer is totally lacking in positional order, such that the polymer chains are oriented randomly and intertwined. In contrast, a semi-crystalline polymer containing regions where the polymer chains are packed together in an organized fashion. The degree of crystallinity of a polymer influences the properties of the polymer, including hardness and melting point. PET is a crystallizable polymer, meaning that it is available in an amorphous form or a semi-crystalline form.

[0006] To obtain the highest quality end product, the PET bottle manufacturing process must be optimized for speed and predictability. Generally, it is thought that PET preforms should be amorphous because highly crystalline preforms are difficult to stretch blow mold. Conversely, a high degree of crystallinity is desirable in the PET bottle produced from the preform, in order to provide necessary strength and barrier properties to the container. Under current manufacturing methods, the desired crystallinity is imparted during the stretch blow molding process by heating, stretching, and blowing the amorphous preform.

[0007] There remains a need to continue to improve the performance and shelf-life of polymer containers, such as PET bottles.

[0008] There further remains a particular need to improve the performance and shelf-life of polymer containers, such as PET bottles, utilizing established manufacturing methods that retain desired speed and predictability.

SUMMARY OF THE INVENTION

[0009] The present invention is directed to methods, devices and systems for making polymer preforms having a controlled amount of stress and molecular orientation, as well as to the polymer preforms formed thereby. The present invention also extends to methods for making polymer containers from such polymer preforms, as well as to the polymer containers formed thereby and packaged beverages comprising such containers. Advantageously, the polymer containers of the present invention offer improved performance, including but not limited to extended shelf-life.

[0010] The polymer component of the present invention may vary. In one embodiment, the polymer component is a thermoplastic polymer such as a polyester. In a particular embodiment, the polymer component is PET or a PET copolyester.

[0011] In a first aspect, the present invention is a method of making a polymer preform having a controlled amount of stress and molecular orientation, comprising (i) supplying a polymer resin; (ii) melting the polymer resin to form a polymer melt; (iii) applying stress to the polymer melt to form a stressed polymer melt (iv) introducing the stressed polymer melt into one or more mold cavities; (v) permitting the stressed polymer melt to cool, thereby forming a polymer preform having a controlled amount of stress and molecular orientation; and (vi) removing the polymer preform from the mold cavity.

[0012] In one embodiment, the stress is applied by introducing the polymer melt into a hot runner comprising at least one channel having a shape and dimensions suitable to provide sheer to the polymer melt. In a particular embodiment, the shape is non-cylindrical. In a specific embodiment, the shape is rectangular. In another particular embodiment, the minimum axis of the channel cross section is significantly less than the maximum axis. In yet another particular embodiment, the width of the channel is between about three and about ten times greater than height of the channel.

[0013] In one embodiment, the channel has a single portion. In another embodiment, the channel has two or more portions. In a specific embodiment, the channel has a first receiving portion and a second shearing portion.

[0014] In one embodiment, the sheer is provided at a sheer rate of between about 40 sec-

1 and 60 sec-1.

[0015] In another embodiment, the polymer preform has a relative orientation index of between about 1.0 and about 1.6.

[0016] In a second aspect, the present invention is a hot runner for use in manufacturing polymer preforms, comprising at least one channel having a shape and dimension suitable to provide sheer to a polymer melt. In one embodiment, the hot runner is housed within a hot runner assembly or a injection molding system.

[0017] In one embodiment, the channel has a single portion. In another embodiment, the channel has more than one portion. In a specific embodiment, the channel has a first receiving portion and a second shearing portion.

[0018] In a third aspect, the present invention is an injection molding system or a hot runner assembly comprising a hot runner having at least one channel, wherein the shape and dimension suitable to provide sheer to a polymer melt.

[0019] In a fourth aspect, the present invention is a polymer preform having a controlled amount of stress and molecular orientation.

[0020] In one embodiment, the polymer preform has a relative orientation index of about

1.2 to about 1.6.

[0021] In a fifth aspect, the present invention is a method of forming a polymer container, comprising (i) providing a polymer preform having a controlled amount of stress and molecular orientation and (ii) stretch blow molding the preform to form a polymer container.

[0022] In one embodiment, the container is a beverage container. In a particular embodiment, the beverage container is a bottle.

[0023] In a sixth aspect, the present invention is a container, wherein the container is formed from a preform having a controlled amount of stress and molecular orientation. In one embodiment, the container is a beverage container. In a particular embodiment, the container is a bottle. [0024] In a seventh aspect, the present invention is a packaged beverage comprising a container body having an outer surface and an interior space, wherein the container body is formed by blow molding a polymer preform having a controlled amount stress and molecular orientation. In one embodiment, the container is a beverage container. In a particular embodiment, the beverage container is a bottle.

[0025] In a specific embodiment, the packaged beverage is a juice, water or carbonated beverage.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings illustrate only exemplary embodiments of the invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments. The elements and features shown in the drawings are not necessarily drawn to scale, emphasis instead being placed upon clearly illustrating the principles of the exemplary embodiments. Additionally, certain dimensions or positionings may be exaggerated to help visually convey such principles. In the drawings, reference numerals designate like or corresponding, but not necessarily identical, elements.

[0027] Figure 1 is a exemplary schematic diagram of a general method for making PET preforms.

[0028] Figure 2A-C show various views of an exemplary hot runner channel in accordance with certain exemplary embodiments.

[0029] Figures 3A-D show various views of another exemplary hot runner channel in accordance with certain exemplary embodiments.

[0030] Figures 4 shows a flow chart of a method for creating a PET preform using certain exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention relates generally to methods, devices and systems for forming polymer articles, including polymer preforms and polymer containers, as well as to the polymer articles themselves.

[0032] Exemplary embodiments of the invention will now be described in detail, including with reference to the accompanying figures. Like, but not necessarily the same or identical, elements in the various figures are denoted by like reference numerals for consistency. In the following detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure herein. However, it will be apparent to one of ordinary skill in the art that the exemplary embodiments herein may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

I. Polymer Material

[0033] While the present disclosure is generally with reference to polyethylene terepthalate or PET, it should be understood that the present invention can be employed for other polyesters and polymers more generally, including polymer blends. Representative, non-limiting examples of other polymers for use in the present invention include polyamides, polycarbonates, polyolefins, and combinations thereof.

[0034] In one embodiment, the polymer is a thermoplastic polymer. In a particular embodiment, the thermoplastic polymer is a polyester or co-polyester. In a specific embodiment, the polyester is PET or a modified PET. Modified PET is considered to include PET co- polyesters, copolymers and other PET derivatives. Suitable PET co-polyesters for use in the present invention include, for example, PET co-polymerized with small amounts of diacids or glycols. Representative, non-limiting, co-monomers include cyclohexane dimethanol (CHDM) naphthalene dicarboxylic acid (NDA) and isophthalic acid. PET co-polyesters may have stretching and/or crystallization behaviors distinct from PET, as would be understood to one of skill in the art.

[0035] Structurally, in the solid state, polymers are either amorphous or semi-crystalline

(only very rarely are polymers able to crystallize completely). Amorphous polymer materials contain molecules that are randomly, rather than periodically, arranged. Put another way, amorphous polymer materials lack positional order on the molecular scale. Given the total absence of positional order, the strength of amorphous polymers is temperature dependent, i.e., as the temperature increases, the amorphous polymer will soften. The defining temperature for amorphous polymers is the glass transition temperature (TQ Below this temperature, the amorphous polymer chains become immobilized and rigid and behave like glass. Above this temperature, the amorphous polymer becomes rubbery.

[0036] Semi-crystalline polymer materials contain both amorphous regions and regions of three-dimensional order. The range of order may be as small as about 2 nm in one (or more) crystallographic direction(s) and is usually below 50 nm in at least one direction. Semi- crystalline polymers do not exhibit a clear Tg or rubbery region although a Tg is often quoted for such materials as the amorphous parts of the structure will undergo some transition. For these polymers the main transition occurs at the melt temperature (Tm), i.e. when the crystalline regions break down.

[0037] Crystallization affects the optical, mechanical, thermal and chemical properties of the polymer. The crystallinity of polymers is characterized by the degree of crystallinity, which be expressed as either a fraction or a percentage (percentage crystallinity). When expressed as a fraction, the degree of crystallinity reflections the fractional amount of crystallinity in the polymer sample and ranges from zero (0) for a completely non-crystalline polymer to one (1) for a theoretical completely crystalline polymer. When expressed as a percentage, the degree of crystallinity reflects the percentage of the volume of the material that is crystalline, ranging from 0% for a completely non-crystalline polymer to 100% for a theoretical completely crystalline polymer (as noted above, polymers are only rarely completely crystalline). PET is a slowly crystallizing polymer that can be obtained with different degrees of crystallinity as a result of specific thermal and/or mechanical treatment to which it is submitted.

[0038] The degree of crystallinity can be determined by several experimental techniques, as would be understood by one of skill in the art. Among the most commonly used are: (i) X-ray diffraction, (ii) calorimetry, (iii) density measurements, and (iv) infrared spectroscopy (IR). The degree of crystallinity may depend on the method of measurement and it can be expressed as a weight fraction Kw or a volume fraction Kv.

[0039] Molecular orientation refers to the alignment of molecular chains in one direction. It is distinct from, but related to, crystallinity. Molecular orientation can be determined by various methods familiar to those of skill in the art. Representative methods include birefringence as well as Polarized Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (Polarized ATR-FTIR). See, e.g., Everall, N.; MacKerron, D.; Winter, D.; "Characterization of biaxial orientation gradients in poly(ethylene terephthalate) films and bottles using polarized attenuated total reflection FTIR spectroscopy", Polymer, Vol. 43, 2002, pp. 4217-4223. Lofgren, E. A.; Jabarin, S. A.; "Polarised Internal Reflectance Spectroscopic Studies of Oriented Poly(ethylene terephthalate)", Journal of Applied Polymer Science, Vol. 51, 1994, pp. 1251-1267. Lin, S.-B.; Koenig, J.; "Spectroscopic Characterization of the Rotational Conformations in the Disordered Phase of Poly(ethylene Terephthalate)", Journal of Polymer Science: Polymer Physics Edition, Vol. 20, 1982, pp. 2277-2295.

[0040] Preferably, the Tg of the polymer used in the various aspects of the present invention is greater than room temperature, i.e., about 20°C. In a particular embodiment, the Tg of the polymer is greater than about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 1 10, about 120 or about 150 °C. In a particular embodiment, the Tg of the polymer is between about 70 °C.

[0041] In a particular embodiment, the polymer is PET or a modified PET or PET derivative. Depending on its processing and thermal history, PET may exist as either an amorphous (transparent) and as a semi-crystalline polymer. The semi-crystalline material may appear transparent (particle size < 500 nm) or opaque and white (particle size up to a few microns) depending on its crystal structure and particle size. In one embodiment, the PET is completely amorphous, i.e., as a degree of crystallization of zero.

II. Method for Making the Polymer Preform

[0042] In one embodiment, the present invention is a method for making a polymer preform having a controlled amount of stress and molecular orientation.

[0043] Polymer preforms, such as PET preforms, are generally manufactured by injection stretch blow molding. It is typically a two-step process, involving a first injection molding step and a second stretch blow molding step. The rest of the first step of the process is a preform, while the result of the second step of the process is an end use polymer article, such as a polymer container.

[0044] Injection molding refers to a process by which malleable materials are forced under pressure into a closed mold. The material solidifies and retains the shape of the mold. A variety of injection molding systems are known in the art; each generally includes an injection molding machine and a mold. There are two main types of injection molds: cold runner and hot runner. A runner is the channel in the mold that conveys the plastic from an injection unit of an injection molding machine to at least one mold cavity, generally defined by a pair of mold plates. A cold runner system is a simply a channel formed between the two halves of the mold, for the purpose of carrying plastic from the injection molding machine to the mold cavities. Each time the mold opens to eject the newly formed plastic parts, the material in the runner is ejected as well, resulting in waste. In contrast, a hot runner system is situated internally in the mold and kept a temperature above the melting point of the plastic. A hot runner system typically includes a heated manifold and several heated nozzles, wherein the manifold distributes the plastic entering the mold to the various nozzles which then deliver it to the mold cavities. Hot runner systems are generally further subdivided on the basis of how the heat is applied, i.e., internally or externally.

[0045] Polymer preforms, such as PET preforms, are formed by heating the polymer starting material to form a polymer melt and then introducing the polymer melt into one or more mold cavities having the shape of the desired preform. Upon cooling, a polymer preform is produced. The characteristics of the polymer at the beginning of the process as well as the parameters/conditions exerted on the polymer during injection molding generally determine the characteristics of the polymer preform that results.

[0046] Figure 1 illustrates an exemplary process for manufacturing a PET preform.

Specifically, Figure 1 shows an injection molder 10. The PET 1 12 and optionally, additives 114 are added to a feeder 120. The resulting PET mixture 120 is delivered to a hot melt extruder 140 in which the PET mixture is melted to create a molten PET 130. The hot melt extruder 140 then extrudes the molten PET into one or more hot runners 160 which deliver the modified molten PET to one or more mold cavities 180. The preform 150 is cooled, removed from the injection molder 10 and further processed, as discussed further herein, to provide a finished container 190.

[0047] Variations on the basic method illustrated in Figure 1 are known in the art. Key parameters include the melt residence time, melt temperature, injection pressure and velocity, shooting out temperature, barrel temperature, hold pressure and time (the time and pressure at which the preforms are held in the mold cavity). Optionally, additional steps may be included.

[0048] In a first embodiment of the first aspect of the present invention, a method is provided for forming a polymer preform having a controlled amount of stress and molecular orientation, comprising (i) supplying a polymer resin; (ii) melting the polymer resin to form a polymer melt; (iii) applying stress to the polymer melt to form a stressed polymer melt (iv) introducing the stressed polymer melt into one or more mold cavities; (v) permitting the stressed polymer melt to cool, thereby forming a polymer preform having a controlled amount of stress and molecular orientation; and (vi) removing the polymer preform from the mold cavity. The polymer resin may be melted by heat at a temperature characteristic of the particular polymer resin.

[0049] The method of the present invention is intended to impart molecular orientation to the polymer preform. Molecular orientation can be measured in various ways known to those of skill in the art. In one embodiment, molecular orientation can be measured by polarized ATR-FTIR method, which relies on the measurement of 12 values taken using 4 FTIR spectra. The FTIR spectral features are the peaks at 1410, 1370 and 1340 cm-1, corresponding to a reference peak, the gauche peak, and the trans peak respectively. The four spectra that need to be collected will be with the beam align to the hoop direction of the bottle with the polarizer at 90 ° and 0 °, and the axial direction of the bottle with the polarizer at 90 ° and 0 °. The hoop direction, which is defined as the direction being perpendicular to the long axis of the bottle, typically is the greatest direction of orientation. The axial direction is parallel to the long axis of the bottle. The values determined for comparison and evaluation of orientation are known as spatial attenuation indices (K_x, K_y, and K_z), which are calculated from the absorption values at 1410, 1370 and 1340 cm^"1. The K_x value is the orientation of the material in the hoop direction, the K_y value is the orientation of the material in the axial direction, and K_z is the orientation of the material in a direction that is perpendicular to the plane formed by the directions defined by K_x and K_y. A representative protocol is provided in Example 8. The ratio k_x/A', k_y/A' and k_z/A' can be used to compare the orientation of two samples against one another with k_x/A' indicative of orientation in the axial direction, k_y/A' indicative of orientation in the hoop direction, and kz/A' indicative of orientation through the thickness of the sample. [0050] The controlled amount of stress and molecular orientation may vary according to processing conditions utilized in the method. When the strain is applied at conditions below the melting point but above the glass transition temperature range of the polymer, the polymer orients to a moderate degree. If the strain is applied to the polymer above the melting point, the stress is relieved by the PET chains orienting in the direction of the strain, providing a high degree of orientation. The degree of molecular orientation is typically expressed with reference to the polymer upon cooling, e.g., the polymer preform, rather than the molten polymer.

[0051] In one embodiment, stress is applied to the molten polymer resin by means of one or more hot runners. Generally speaking the melt flow conditions are manipulated within all or a portion of the hot runners to increase the molecular orientation of the molded preforms. More specifically, the shape of the one or more hot runner channels should impart upon the hot melt flowing through the channel a decrease in its cold crystallization temperature. High aspect ratio channels built directly into or onto the hot runner system of an injection molder are employed such that a moderate amount of shear is used to template the resin into a pre-organized, oriented preform. The advantage of imparting a controlled amount (also expressed as degree) of stress and orientation to the preform is that it may enhance the level of orientation of the polymer in the end use article formed therefrom, e.g., the PET bottle formed from the PET preform. The orientation of the polymer in the preform will "template" and enhance the level of crystallinity in the end use polymer article by rearranging the polymer chains in a manner that lowers the energy barriers to crystallization.

[0052] Hot runners of various configurations are known in the art. Generally speaking, a hot runner comprises an inlet opening into which the molten material is supplied, and one or more outlet openings from which the molten material is discharged, and a flow passage or channel, wherein the inlet opening is formed at one end, and the outlet opening is formed at the other end, and the flow passage or channel connects the inlet opening and the outlet opening. According to the present invention, the shape and/or dimensions of the hot runner channel (or portion thereof) is such that an imbalance in the direction and amount of side wall contact is achieved relative to the magnitude of each of the dimensions of the channel. In other words, the hot runner channel is a shape other than cylindrical (as in the prior art), and the dimensions provide a level of friction-induced shear deep into the polymer. This is done using "flattened" channels, i.e., channels that have a cross-section such that the minimum axis of the channel cross section the same or less than the maximum axis. In a preferred embodiment, the minimum axis is significantly less than the maximum axis. [0053] In a particular embodiment, the hot runner channel is rectangular in cross-section.

According to this embodiment, the maximum axis is equal to or greater than y (y is the minimum axis).

[0054] In another particular embodiment, the hot runner channel is oblong, having x and y dimensions meeting the parameters defined above.

[0055] The hot runner channel may be formed of any suitable material, as would be understood to one of skill in the art.

[0056] Figures 2A-C show various views of an exemplary hot runner channel 260 in accordance with certain exemplary embodiments. Specifically, Figure 2A shows a perspective view of the hot runner channel 260. In addition, Figure 2B shows a top view and Figure 2C shows a side view of the hot runner channel 260. Referring to Figures 2A-C, the hot runner channel 260 is rectangular in shape and has a length 266, a width 262, and a height 264.

[0057] In certain exemplary embodiments, the width of the hot runner is from about two times greater than the height to about 50 times greater than the height. In a specific embodiment, the width of the hot runner channel is about 3 to about 10 times greater than the height. In a particular embodiment, the width of the hot runner channel is about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 20, about 30, about 40 or about 50 times greater than the height.

[0058] In certain exemplary embodiments, the shear rate of between approximately 40 sec-1 and 60 sec-1. In a specific embodiment, the shear rate is about 40, about 45, about 50, about 55 or about 60 sec-1. The shear rates can be dependent on one or more of a number of factors, including but not limited to the mass of the molten polymer, the temperature of the molten polymer, and the extrusion rate of the hot melt extruder. In certain exemplary embodiments, the shear is applied to the molten when the temperature of the molten is below the melting point of the molten polymer and within the glass transition temperature range of the polymer of the molten PET 130. Table 1 below shows certain preformance parameters exemplary hot runner channels of Example 2.

[0059] As described above with regard to Figures 2A-C, an exemplary hot runner channel described herein can have a single portion, having a uniform length, width, and height along such portion. Alternatively, as shown in Figures 3A-D, certain exemplary hot runner channels can have two or more portions, where each portion has a unique length, width, and/or height relative to the other portions. In such a case, the multiple portions may be mechanically coupled by joining segments. Such joining segments can be oriented and/or arranged in one or more of a number of ways, including but not limited to perpendicular to one or both joined portions, tapered relative to the joined portions, planar, segmented, three dimensional, and curved. The multiple portions and/or joining segments of such a hot runner channel can be formed from a single piece (e.g., formed in a mold) or discrete pieces that are mechanically coupled using one or more of a number of methods, including but not limited to welding, epoxy, compression fittings, and fastening devices.

[0060] For example, as shown in Figures 3A-C, the exemplary hot runner channel 360 has a first portion 310 (i.e., a receiving channel) and a second portion 320 (i.e., a shearing channel) that are each mechanically coupled to a joining segment 330. Specifically, Figure 3A shows a top view of the exemplary hot runner channel 360. Further, Figure 3B shows a cross sectional front view of the receiving channel 310, and Figure 3C shows a cross sectional front view of the shearing channel 320.

[0061] Referring to Figures 1 and 3A-C, the receiving channel 310 and the shearing channel 320 of the hot runner channel 360 are rectangular in shape. The receiving channel 310 has a length 316, a width 312, and a height 314. In certain exemplary embodiments, the dimensions of the receiving channel 310 are substantially similar to the corresponding dimensions of the hot melt extruder 140 to which the receiving channel 310 is mechanically coupled. Likewise, the shearing channel 320 has a length 326, a width 322, and a height 324. At least one of the length, the width, and the height of the receiving channel can be different than the length, the width and the height of the shearing channel.

[0062] As with the hot runner channel of Figures 2A-C, the width of the receiving channel 310 and the width of the shearing channel can be at least three times greater than the height of the receiving channel and the height of the shearing channel. As stated above, the width and height of the receiving channel may correspond to the opening in the hot melt extruder to which the receiving channel of the hot runner channel couples.

[0063] In addition, the shearing channel of the hot runner channel can have a length and width greater than the length and the width of the receiving channel, and the height of the receiving channel is greater than the height of the shearing channel.

[0064] The joining segment 330 acts as a transition channel between, in terms of the flow of the molten PET 130 through the hot runner channel 260, an exiting end of the receiving channel 310 and a receiving end of the shearing channel 320. The joining segment 330 is mechanically coupled to the receiving channel 310 and the shearing channel 320. The joining segment 330 can have a cross-sectional shape that generally matches the corresponding cross- sectional shape of the receiving channel 310 or the shearing channel 320. For example, the cross-sectional shape of the receiving channel 310, the joining segment 330, and the shearing channel 320 can be rectangular, even though each rectangular shape has varying widths and/or heights. In addition, or in the alternative, the cross-sectional shape of the joining segment 330 can change throughout the length of the joining segment 330.

[0065] The joining segment 330 of the hot runner channel 360 may be continuously and linearly tapered. The horizontal sides and the vertical sides may be trapezoidal in shape, where the length of each is measured normally from the top side (the side coupled to the receiving channel 310) and the bottom side (the side coupled to the shearing channel 320). The joining segment can have other shapes and configurations. For example, rather than the vertical sides and the horizontal sides of the joining segment being planar segments, the joining segment can consist of a conical shape, either in two or more discrete non-planar segments (e.g., vertical sides and horizontal sides) or in a single non-planar (e.g., conical) segment.

[0066] In certain other exemplary embodiments, the length of the receiving channel is significantly less than the lengthy of the shearing channel. Conversely, the length of the shearing channel may be significantly greater than the length of the receiving channel.

[0067] The hot runner channel can have multiple shearing channels, each having the same or different dimensions relative to each other, which are coupled by multiple joining sections, which also can have the same or different dimensions relative to each other.

[0068] Figure 4 is a flowchart of a method 400 for creating a PET preform in accordance with certain exemplary embodiments. While the various steps in this flowchart are presented and described sequentially, one of ordinary skill will appreciate that some or all of the steps may be executed in different orders, may be combined or omitted, and some or all of the steps may be executed in parallel. Further, in one or more of the exemplary embodiments, one or more of the steps described below may be omitted, repeated, and/or preformed in a different order. In addition, a person of ordinary skill in the art will appreciate that additional steps not shown in figures may be included in preforming this method. Accordingly, the specific arrangement of steps should not be construed as limiting the scope.

[0069] Now referring to Figure 4, the exemplary method 400 begins at the START step and proceeds to step 402, where the molten PET 130 is received. In certain exemplary embodiments, the molten PET is received by one or more receiving channels 310 of a hot runner channel 360. The receiving channel 310 can include a width 312 and a height 314. The molten PET 130 can be generated by heating, using a hot melt extruder 140, a PET mixture 125. The PET mixture 125 can be generated by mixing, using a feeder 120, PET 112 and, optionally, at least one additive 114.

[0070] In step 406, a shear force is applied to the molten PET. In certain exemplary embodiments, a modified molten PET is generated by the shear force that is applied to the molten PET. The shear force can be applied to the molten PET as the molten PET is extruded through the shearing channel 320. The shear force can result from a difference between the width of the receiving channel and the width of the shearing channel. In addition, or in the alternative, the shear force can result from a difference between the height of the shearing channel and the height of the receiving channel. In certain exemplary embodiments, the shear force is applied to the molten PET 130 when a temperature of the molten PET 130 is less than a melting point of the molten PET 130 and within a glass transition temperature range of the molten PET 130. When step 406 is completed, the process continues to the END step. In such a case, subsequent to step 406, the modified molten PET 135 can be cooled in a mold cavity to generate a PET preform, which can then be converted into a container using a stretch blow molder.

[0071] As discussed above, the polymer resin may be any suitable resin, including but not limited to, PET or a PET derivative. Additives may be included, either in the polymer resin supplied for melting or during the melting process. Representative, non-limiting additives include optical brighteners, ultraviolet light stabilizers, reheat additives and the like. The polymer mean be melted by any suitable means, for example, a hot melt extruder 140. The hot melt extruder can use one or more of a number of extruding technologies and that operate at any of a number of speeds, which may be either constant or variable over a period of time. In a particular embodiment, the hot melt extruder comprises a screw drive. In another particular embodiment, the hot melt extruder operates at a speed of about 30, about 50 or about 50 rotations per minute (rpm).

[0072] Other optional steps may be used in connection with the present method. In a particular embodiment, the method of the present invention further comprises drying the polymer resin prior to melting. For example, PET resin is hygroscopic, i.e., it picks up moisture from air, and may benefit from or require drying prior to processing.

[0073] In another particular embodiment, the method further comprises rapidly cooling the stressed or modified molten polymer. Rapidly cooling the stressed molten polymer resin capture the orientation of the polymers of the modified molten polymer. In a specific embodiment, the stressed molten polymer resin is cooled in less than about one minute and in a more specific embodiment, less than about 30 seconds.

[0074] In a particular embodiment, comprising (i) supplying a PET resin; (ii) melting the PET resin by heating to form a melted polymer resin; (iii) delivering the melted PET resin to a hot runner, wherein the hot runner comprises at least one channel shaped to apply stress to the molten polymer, thereby forming a stressed molten polymer resin; (iv) introducing the stressed molten polymer resin into one or more mold cavities; (v) permitting the melted polymer resin to cool, thereby forming a polymer preform having a controlled amount of stress and molecular orientation; and (vi) removing the polymer preform from the mold cavity.

[0075] The method of the present invention imparts a degree of molecular orientation to the resulting polymer preform greater than the molecular orientation of a polymer preform formed by standard preform manufacturing methods. In a particular embodiment, the method produces a polymer preform having a relative orientation index of about 1.0 to about 1.6. and more specifically, a relative orientation index of about 1.0, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5 or about 1.6. A method of calculating relative orientation index is exemplified in Example 8. In another particular embodiment, the method produces a polymer preform having a molecular orientation from about 1 to about 10%, about 10 to about 20%, about 20 to about 30%, about 40%, about 50% or from about 50% greater than a polymer preform formed by standard preform manufacturing methods. In a specific embodiment, the method imparts a produces a polymer preform having a molecular orientation of about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10% greater than a polymer preform formed by standard manufacturing methods. The molecular orientation of the polymer preform of the present invention serves as a template to enhance the crystallinity of the polymer container formed therefrom.

[0076] In certain embodiments, the method of the present invention produces a slight degree of crystallinity (low crystallinity) in the resulting polymer preform. In a particular embodiment, the method produces a degree of crystallinity in the resulting polymer preform of less than about 10%. In a more particular embodiment, the method produces a degree of crystallinity in the resulting polymer preform of between about 1 and about 7%.

III. Device and System For Forming a Polymer Preform

[0077] In another embodiment, the present invention is a device and system for making a polymer article such as a polymer container or more specifically, PET containers including PET bottles.

[0078] In one embodiment, the present invention is a hot runner having at least one channel configured to stress the molten polymer flowing through it, as described herein. In another embodiment, the present invention is a hot runner system or hot runner assembly comprising one or more hot runners configured as described herein. In yet another embodiment, the present invention is an injection molding system comprising one or more hot runners configured as described herein. It will be appreciated that the hot runner system, hot runner assembly and the injection molding system may include components that are known to persons skilled in the art, and these known components will not be described here; these known components are described, at least in part, in the following text books (by way of example): (i) "Injection Molding Handbook" by Osswald/Turng/Gramann (ISBN: 3-446-21669-2; publisher: Hanser), (ii) "Injection Molding Handbook" by Rosato and Rosato (ISBN: 0-412-99381-3; publisher: Chapman & Hill), (iii) "Runner and Gating Design Handbook" by John P. Beaumont (ISBN 1-446-22672-9, publisher: Hanser), and/or (iv) "Injection Molding Systems" 3.sup.rd Edition by Johannaber (ISBN 3-446-17733-7). A representative injection molding system is shown in Figure 1 but should be considered non-limiting.

[0079] More specifically, the present invention is a hot runner for use in manufacturing a polymer preform, comprising one or more channels shaped so that an imbalance in the direction and amount of side wall contact is achieved relative to the magnitude of each of the dimensions of the channel. In a particular embodiment, the hot runner comprises one or more channels having a cross-section such that the minimum axis of the channel cross section is the same or less than the maximum axis. In a specific embodiment, the hot runner comprises one or more channels having a cross-section such that the minimum axis of the channel cross section is less than the maximum axis. In a preferred embodiment, the hot runner comprises one or more channels having a cross-section such that the minimum axis of the channel cross section is significantly less than the maximum axis.

[0080] In another particular embodiment, the present invention is a hot runner comprising one or more channels having a shape other than cylindrical.

[0081] In a specific embodiment, the channel has a rectangular cross section.

[0082] In another specific embodiment, the channel has an oblong shape.

[0083] In some embodiments, the hot runner channel has a single portion. In an alternative embodiment, the apparatus of the present invention is a hot runner comprising two or more portions, where each portion has a unique length, width, and/or height relative to the other portions. In such a case, the multiple portions may be mechanically coupled by joining segments. Such joining segments can be oriented and/or arranged in one or more of a number of ways, including but not limited to perpendicular to one or both joined portions, tapered relative to the joined portions, planar, segmented, three dimensional, and curved. The multiple portions and/or joining segments of such a hot runner channel can be formed from a single piece (e.g., formed in a mold) or discrete pieces that are mechanically coupled using one or more of a number of methods, including but not limited to welding, epoxy, compression fittings, and fastening devices. As a non-limiting example, the exemplary hot runner channel has a first receiving channel and a shearing channel that are each mechanically coupled to a joining segment. [0084] The present invention also includes a hot runner system comprising a hot runner having one or more channels shaped so that an imbalance in the direction and amount of side wall contact is achieved relative to the magnitude of each of the dimensions of the channel. In a particular embodiment, the hot runner system comprises a hot runner having one or more channels having a cross-section such that the minimum axis of the channel cross section is significantly less than the maximum axis.

[0085] The present invention also includes an injection molding system, including (i) a feeder; (ii) a hot molt extruder; and (ii) one or more hot runners, wherein at least one of the hot runners has one or more channels configured so that an imbalance in the direction and amount of side wall contact is achieved relative to the magnitude of each of the dimensions of the channel.

IV. Polymer Preform

[0086] In a second aspect, the present invention is a polymer preform having controlled amount of stress and molecular orientation. The controlled amount of stress and molecular orientation advantageously permits the polymer preform to serve as a template for enhanced crystallization of a polymer container formed therefrom, resulting in a container with enhanced preformance characteristics. More specifically, the preform lowers the energy barrier for crystallization of the polymer article produced therefrom

[0087] The polymer preform may be of any suitable shape, size or color. Examples of suitable polymer preforms and container structures are disclosed in U.S. Pat. No. 5,888,598, the disclosure of which is expressly incorporated herein by reference in its entirety. Preferably, the polymer preform has a blowable geometric form. In a particular embodiment, the preform comprises an open ended mouth forming portion, an intermediate body forming portion, and a closed base forming portion. In a specific embodiment, the preform has a threaded neck finish. In a particular embodiment, the preform has a threaded neck finish which terminates at its lower end in a capping flange, below which there is a generally cylindrical section which terminates in a section 1 18 of gradually increasing external diameter so as to provide for an increasing wall thickness.

[0088] The polymer preform of the present invention can be blow molded to form a polymer container. Generally, the amount of stress and molecular orientation in the preform does not interference with further processing, i.e., stretch blow molding, of the preform.

[0089] In a particular embodiment, the polymer preform has a relative orientation index of about 1.0 to about 1.6. and more specifically, a relative orientation index of about 1.0, about

1.1, about 1.2, about 1.3, about 1.4, about 1.5 or about 1.6. In another particular embodiment, polymer preform has a molecular orientation of about 1 to about 10%, about 10 to about 20%, about 20 to about 30%, about 40%, about 50% or greater than about 50%. In a specific embodiment, the method imparts a degree of molecular orientation to the polymer preform of about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10%. The molecular orientation and relative orientation index can be measured and described as taught herein and would be understood by one of skill in the art. Relative molecular orientation is expressed with reference to a control, generally a standard polymer preform, i.e., a preform formed according to known and commonly utilized methods.

[0090] In certain embodiments, the polymer preform is amorphous.

[0091] In certain other embodiment, the polymer preform is semi-crystalline. More particularly, the polymer preform may exhibit a slightly semi-crystalline nature, i.e., have a low degree of crystallinity. In a particular embodiment, polymer preform has a degree of crystallinity of less than about 10%. In a more particular embodiment, the polymer preform has a degree of crystallinity of between about 1% and about 7%.

IV. Method for Making the Polymer Container

[0092] Further operation on the polymer preform of the invention will be affected by its controlled amount of stress and molecular orientation.

[0093] In one embodiment, the polymer preform is further processed by blow molding to form a polymer article such as a polymer container. Methods of blow molding (or stretch blow molding) are known to those of skill in the art. The container may be made from the polymer preform in single stage, two stage, and double blow molding manufacturing systems. The purpose of blow molding the polymer preform is to provide a clear polymer container, such as a PET bottle, with sufficient desirable preformance characteristics, including but not limited to, extended shelf-life. The method may be, for example, a standard reheat stretch blow mold process.

[0094] According to one embodiment, a polymer preform having a controlled amount or degree of stress and molecular orientation is blow molded into a container. In a particular embodiment, the method comprises: (i) supplying a polymer preform having a controlled amount of stress and molecular orientation; (ii) heating the preform; (iii) positioning the heated preform inside of a mold; (v) blowing the heated preform; and (v) removing the polymer article so formed. Variations on the blow molding method described here are known in the art and contemplated by the present invention.

[0095] In a particular embodiment, the polymer preform is first heated, positioned in the mold, and an axial stretch rod is then inserted into the open upper end and moved downwardly to axially stretch the preform. Subsequently or simultaneously, an expansion gas is introduced into the interior of the preform to expand portions of the preform outwardly into contact with the interior surface of the mold.

[0096] The heater used to heat the preform may be of any suitable type. Preferably, the heater is capable of heating to a temperature suitable for stretching and orientation of the plastic from which the preform is made, which temperatures are familiar to those of skill in the art. In one embodiment, the preform is a PET preform and the heater provides temperatures in the range from about 70 to about 130°C, from about 85°C to about 130°C, and more preferably, about 105°C. The mold may be of any suitable type. For example, the mold may be substantially symmetrical and/or simple in shape with an opening at one end. The mold may be a single piece or two pieces, e.g., a split mold. Blowing may be accomplished by applying a blowing pressure for a suitable time and suitable pressure to cause the preform to expand. The pressure may be varied to suit the particular polymer used. If the preform is a PET preform, the pressure may be, for example, between about 3 to 40 Bar.

[0097] In one embodiment, the present invention is a method of forming a polymer article comprising (i) supplying a polymer resin; (ii) melting the polymer resin by heating to form a polymer melt; (iii) applying stress to the polymer melt to form a stressed polymer melt (iv) introducing the stressed polymer melt into one or more mold cavities; (v) permitting the stressed polymer melt to cool, thereby forming a polymer preform having a controlled amount of stress and molecular orientation; (vi) removing the polymer preform from the mold cavity; (vii) heating the preform; (viii) positioning the heated preform inside of a mold having a desired shape; (ix) blowing the heated preform by injection of gas under pressure at a first pressure for a first time period; and (x) removing the polymer article so formed.

[0098] In a variation on the two-step process disclosed herein, a polymer preform is produced and blown into a bottle in one and the same production-line, i.e., according to a one- step process.

[0099] In one embodiment, the method of the present invention increases the molecular orientation of the polymer container or article in comparison to standard polymer containers or articles, i.e., manufactured according to standard methods of manufacture. The increase in molecular orientation can be measured and expressed as a relative orientation index or a percentage.

[00100] In another embodiment, the method of the present invention increases the degree of crystallinity of the polymer container in comparison to standard methods of polymer container manufacturing. A high degree of crystallinity is desirable for polymer containers, such as Pet containers, because it confers improves the performance and/or shelf life of the container. More specifically, a high degree of crystallinity improves the gas barrier and mechanical properties (creep resistance, toughness, burst strength) of the polymer container. The present method increases the degree of crystallinity of the polymer article by providing a polymer preform having a controlled amount of stress and molecular orientation which preform then serves as a template for crystallization, i.e., promotes enhanced crystallization, of the polymer container formed therefrom. Additional crystallinity, i.e., beyond that degree promoted by the preform template of the present invention, is imparted to the polymer container by conventional processing of the preform. Strain-induced crystallinity results from the rapid mechanical deformation of PET, and generates extremely small, transparent crystallites.

[00101] In a particular embodiment, the method of the present invention increases the degree of crystallinity of the polymer article by about 1 to about 5%, about 5 to about 10%, about 10 to about 15%, about 15 to about 20%, about 20 to about 25% or about 25% to about 40%. In a particular embodiment, the method of the present invention increases the degree of crystallinity of the polymer article by about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9 or about 10%. The increase according to the present method is with reference to standard methods of production of polymer containers from standard polymer preforms.

[00102] The method of the present invention permits manufacture of polymer articles having improved performance characteristics, including but not limited to increased shelf-life. More specifically, the method produces a container having improved thermal resistance, gas barrier properties and mechanical strength. In a particular embodiment, the thermal resistance of the container is increased by about 1 to about 25%, or more particularly, about 1, 5, about 10, about 15, about 20 or about 25% . In another particular embodiment, the gas barrier properties are improved by about 1 to about 25%, or more particularly, about 1, about 5, about 10, about 15, about 20 or about 25%. In another particular embodiment, the mechanical strength of the container is improved about 1 to about 25%, or more particularly, about 1, about 5, about 10, about 15, about 20 or about 25%. The method can be used to produce containers with reliability and speed.

[00103] In exemplary embodiments, a hot fill package produced according to the present method could be filled at hotter temperatures, extending the shelf life of the product contained therein relative to current standards. In other exemplary embodiments, gas diffusion can be reduced, as CO₂ permeability is reduced by 1.3% for each additional 1% of crystallinity in the bottle.

V. The Polymer Container

[00104] The polymer preform is used to manufacture a polymer article, such as a polymer container, with enhanced properties such as improved thermal resistance, gas barrier properties and mechanical strength. As described above, the polymer may vary and in one embodiment, the polymer is PET or a PET co-polyester.

[00105] In one embodiment, the article is a container, such as a food or beverage container. The beverage container may be used, for example, to house a beverage such juice, water or a carbonated beverage. The container may be any suitable beverage containers, such as a bottle or jar.

[00106] The volume of the container may vary according to the beverage container and/or commercial demand. In one embodiment, the container has a volume within the range from 0.25 to 5 liters. In a particular embodiment, the container has a volume of about 12 ounces, 16 ounces, 20 ounces or 24 ounces. In another particular embodiment, the container has a volume of about 250, 300, 333, 355, 472, 500, 590, 750 or 850 ml.

[00107] Desirably, the polymer article of the present invention has a high degree of crystallinity. In one embodiment, the polymer article has a degree of crystallinity of from about 15 to about 60%. In a particular embodiment, the polymer article has a degree of crystallinity of about 15, about 20, about 25, about 30, about 35, about 40, about 50, about 55 or about 60%. The percentage crystallinity can be measured by any suitable method including, for example, differential scanning calorimetry (DSC).

[00108] In a particular embodiment, the present invention is a polymer beverage container, such as a PET bottle, having a degree of crystallinity of about 25% or more.

[00109] In another particular embodiment, the present invention is a polymer beverage container, such as a PET bottle, having a degree of crystallinity of about 50% or more.

[00110] In yet particular embodiment, the present invention is a polymer beverage container, PET container having a degree of crystallinity of about 60%.

[00111] In one embodiment, the polymer container is suitable for use in hot-fill applications. Specifically, the container can withstand temperatures greater than about 85°C.

[00112] In another embodiment, the present invention is a packaged beverage. In a particular embodiment, the packaged beverage includes a container body having an outer surface and an interior space, wherein the container body is formed by blow molding a polymer preform having a controlled amount of stress and molecular orientation. The packaged beverage may be, for example, juice, water or a carbonated beverage.

[00113] The examples below serve to further illustrate the invention, to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices, and/or methods claimed herein are made and evaluated, and are not intended to limit the scope of the invention. In the examples, unless expressly stated otherwise, amounts and percentages are by weight, temperature is in degrees Celsius or is at ambient temperature, and pressure is at or near atmospheric.

EXAMPLES

Example 1:

[00114] A hot runner channel is provided having a length of approximately 4.588 inches, a width of approximately 0.16 inches and a height of approximately 0.043 inches.

Example 2:

[00115] A hot runner channel is provided having a receiving channel, a shearing channel and a joining segment. The receiving channel has a length of approximately 0.25 inches, a width of approximately 0.16 inches and a height of approximately 0.043 inches. The shearing channel has a length of approximately 3.838 inches, a width of approximately 0.625 inches, and a height of approximately 0.011 inches. The vertical sides of the joining segment have a length of approximately 0.5003 inches and the horizontal sides have a length of approximately 0.5514 inches.

Example 3:

[00116] A hot runner channel is provided having a receiving channel, a shearing channel and a joining segment. The receiving channel has a length of approximately 0.125 inches, a width of approximately 0.16 inches and a height of approximately 0.043 inches. The shearing channel has a length of approximately 4.338 inches, a width of approximately 0.32 inches and a height of approximately 0.0215 inches. The joining segment has vertical sides with a length of approximately 0.1255 inches and horizontal sides with a length of approximately 0.1484 inches.

Example 4:

[00117] A hot runner channel is provided having a receiving channel, a shearing channel and a joining segment. The receiving channel has a length of approximately 3.0588 inches, a width of approximately 0.16 inches and a height of approximately 0.625 inches. The shearing channel has a length of approximately 1.0 inches, a width of approximately 0.043 inches and a height of approximately 0.01 1 inches. The horizontal sides of the joining section have a length of approximately 0. 5514 inches, and the vertical sides 334 have a length of approximately 0.5003 inches. Example 5:

[00118] A ThermoHaake Minilab II twin screw extruder was used to extrude dried PET resin through a 4.5 inch channel at 270°C. The control channel maintained the dimensions of the exit from the extruder (0.160 inches x 0.043 inches, 0.00688 in², 26.8% ratio of short edge to long edge). The shearing channel employed to orient the resin had an exit dimension of 0.625 inches x 0.01 1 inches (0.00688 in², 1.76% short edge to long edge) over a length of 3.8 inches. At a constant screw speed of 50 rpm, resin samples were extruded through the dies and samples collected in a form that maintained the ribbon/film structure without additional stretching of the resin.

The following data was collected:

[00119] For Table 1 above, the hot runner channel from Example 2 is compared to a control hot runner channel (i.e., a tubular hot or cylindrical runner channel currently known in the art). The results suggest that the shearing channel of the hot runner channel is templating crystallization of the molten PET through orientation. The melting point (Tm) of the strand through the shearing channel is higher than that of the control indicating that the increased shear through the shearing channel is not degrading the resin (in other words, a molten PET having lower molecular weight has a lower melting point). The isothermal crystallization rate (IC_rate) and the crystallization temperatures (T_c) are clearly in support of a templated, oriented resin. The lower crystallization temperature of the melt in the shearing channel (T_c=138.74 °C vs 141.15 °C) indicates that lower energy is required to induce crystallization, consistent with templating. The faster IC rate for the sheared strand sample (0.83 minutes to 1.13 minutes) is also indicative of pre-organization of the polymer chains in the molten PET. The enthalpy of melting, however, does not indicate that anything more than pre-organizing the resin of the molten PET is occurring. This is indicated by the small difference in the total energy associated with the melting energy and the very small difference in the melting temperatures.

Example 6:

[00120] The following Table 2 shows intrinsic viscosity (IV) of the hot runner channels as described above with respect to Example 3 (denoted as C) and Example 4 (denoted as E) in relation to a control hot runner channel. The data show that for hot runner channel E (referred to in Table 2 as Die E), the IV loss was much more significant than that observed for hot runner channel C (referred to in Table 2 as Die C). Therefore, only hot runner channel C was compared to the control. In addition, a number of other hot runner channels (referred to as A, B, D, F, G, H, and I) according to exemplary embodiments described herein were tested.

Table 1. IV values for samples tested

Die C-G 0.527

Die C-H 0.557

Die C-I 0.546

Die E-A 0.495

Die E-B 0.496

Die E-C 0.499

Die E-D 0.479

Die E-E 0.481

Die E-F 0.473

Die E-G 0.478

Die E-H 0.463

Die E-I 0.479

Table 3 below shows the IV difference between the control and Die C.

Table 3. IV differences between Control and Die C

Variable Difference IV Difference (dL/g)

Control A-Die C-A 0.083

Control B-Die C-B 0.090

Control C-Die C-C 0.111

Control D-Die C-D 0.085

Control E-Die C-E 0.080

Control F-Die C-F 0.085

Control G-Die C-G 0.092

Control H-Die C-H 0.120

Control I-Die C-I 0.046

Example 7: [00121] In addition, as shown in Tables 4 and 5 below, thermal analysis was carried out to determine the effect of the die geometry and shear rate on the crystallinity of the extruded polymer, the crystallization rate, and glass transition. Table 4 shows thermal properties of the control samples, while Table 5 shows thermal properties of Die C.

Table 4. Thermal properties of control samples

Table 5. Thermal properties of Die C

C-F 59.89781 73.59 126.75 134.81 33.01 8.24 232.61 37.59 34.1 0.778571

C-G 79.60584 74.85 125.49 134.37 28.61 9.26 232.42 247.52 39.11 7.5

C-H 61.87226 73.91 128.18 138.27 29.18 9.4 231.93 247.49 36.23 5.035714

C-I 75.57299 74.05 131.68 139.13 32.49 9.53 231.78 246.49 37.33 3.457143

[00122] Percent crystallinity (%X) values for both the controls and the Die C materials are similar. The ranges for the glass transition temperatures (T_g) vary within a small range and are not correlated to the shear rate or rate of the belt speed (i.e., the speed at which the molten PET is extruded through the hot runner channel). There is a good correlation between the effect of shear rate and the increase in cold crystallization in Die C (both onset and max value). On the other hand, there seems to be no correlation between these parameters in the control samples. Further, there appears to be a decrease in the mobility of the molten PET brought on by orientation, which indicates that the rate of the crystallization is faster. The melting point seems to be independent of the shear rate.

Example 8:

Molecular orientation can be measured by polarized ATR-FTIR.

Methodology: The instrument to be used is a PerkinElmer Spectrum 400 FT-IR Spectrometer with a PerkinElmer Universal single reflection Diamond/ZnSe ATR polarization accessory.

Sampling from the bottle: From the label panel of the bottles of interest, find an area of approximately 1.25 cm on a side and mark the hoop directions and axial directions. Carefully excise the section using either scissors or a sharp Exacto® knife. The markings are to remain on the excised sample. When sampling multiple bottles, the sampling areas should be

approximately from the same location on the bottle.

Collecting Data: Using the ATR accessory with the polarizer set to 0°, obtain all spectra, in absorbance mode, from the range of 1600 to 1 100 cm-1, at 4 cm-1 resolution. The beam of the instrument runs from the left side of the instrument to the right, parallel to the front of the instrument. This will be referred to the beam direction. Each sample should have two spectra collected with the hoop direction parallel to the beam direction, one spectrum each with the polarizer set to 0° and 90°. The sample should then be oriented with the beam direction parallel to the axial direction of the bottle sample and two additional spectra collected, one each with the polarizer set to 0° and 90°. The spectra should be collected in absorbance mode. Measure the absorbance at the following wavenumbers for each spectrum: 1410, 1370 and 1340 cm^"1. Determination of Spatial Attentuation Indices: Normalize the data to the value of the measured absorbance at 1410 cm^"1. Specifically, divide the absorbance values measured for a given spectrum by the value of the absorbance at 1410 cm^"1. The value at 1410 cm^"1 should therefore be unity.

There are three constants that are needed that describe the spatial attenuation indices: a=10.64, β=1.87, and γ=19.41. These constants are specific to the refractive index of the crystal used in our particular instrument. The indices are k_a, 1¾, and k_n, referring to the axial direction, the hoop direction and the thickness direction respectively. The values for the orientation indices are comparative from bottle to bottle and an increase in the value of k for a given sample relative to another indicates a greater degree of orientation in that direction. To calculate the indices, the following equations are used k_x =—— * k_v = and

(values for k_z should then be averaged)

Where A is the normalized absorbance value determined for the particular direction and polarizer angle noted. There is typically no change in orientation in the thickness direction and this has been born out in experiments by Jabarin and Lofgren. From the k values, a modified structural factor A' is calculated using the equation:

A = - {k_x + k_y + fc,)

This is followed by the determining the three dimensional contribution of each to A' by dividing the values of k_x, k_y and k_z by A'.

Example 9:

[00123] The ratio of the orientation indices between the control samples and the Die C samples are shown in Table 6 below for the trans (oriented, extended) conformation and the Cis (compact, random) conformation, calculated according to the method provided in Example 8. The ratios converge to 1 at very high shear rates, indicating that at very high shear, the rate of extrusion limits the effect of the die geometry. However, at intermediate shear rates, the effect of the die can be seen to be significant.

Table 2. Relative Orientation Indices of the Samples as a function of Shear Rate (Die

C/Control)

[00124] There is no correlation of the trans conformation in the direction perpendicular to the extruded direction (machine direction). This is expected as the polymers of the molten PET tend to align in the direction in which the material is flowing. For the compact random conformation, similar results are shown for the transverse and machine directions, indicative of a material that may be sensitive to the shear direction but not fully oriented. This would be desirable as much as orientation.

[00125] Modifications and variations of the present invention will be apparent to those skilled in the art from the forgoing detailed description. All modifications and variations are intended to be encompassed by the following claims. All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety.

Claims

CLAIMS What is claimed is:

1. A method of making a polymer preform having a controlled amount of stress and molecular orientation, comprising (i) supplying a polymer resin; (ii) melting the polymer resin to form a polymer melt; (iii) applying stress to the polymer melt to form a stressed polymer melt; (iv) introducing the stressed polymer melt into one or more mold cavities; (v) permitting the stressed polymer melt to cool, thereby forming a polymer preform having a controlled amount of stress and molecular orientation; and (vi) removing the polymer preform from the mold cavity.

2. The method of claim 1, wherein stress is applied by introducing the polymer melt into at least one hot runner comprising at least one channel having a shape and dimensions suitable to provide sheer to the polymer melt.

3. The method of claim 2, wherein the shape is non-cylindrical.

4. The method of claim 2, wherein the shape is rectangular or oblong.

5. The method of claim 1, wherein the minimum axis of the channel cross section is significantly less than the maximum axis.

6. The method of claim 1, wherein the width of the channel is between about three and about ten times greater than height of the channel.

7. The method of claim 2, wherein the hot runner has more than one portion.

8. The method of claim 2, wherein the hot runner channel has a first receiving portion and a second shearing portion, wherein the first and second portions are connected by a joining segment.

9. The method of claim 1, wherein the stress applied is shear.

10. The method of claim 9, wherein the shear has a sheer rate of between about 40 sec-1 and 60 sec-1.

1 1. The method of claim 1, wherein the polymer comprises one or more

thermoplastic polymers.

12. The method of claim 1, wherein polymer comprises one or more polyesters.

13. The method of claim 1 , wherein the polymer comprises polyethylene

terephthalate.

14. The method of claim 1 , wherein the polymer comprises a polyethylene terephthalate copolyester.

15. A hot runner for use in manufacturing polymer preforms, wherein the hot runner comprises at least one channel having a shape and dimension suitable to provide friction-

16. The hot runner of claim 15, wherein the shape is a non-cylindrical.

17. The hot runner of claim 15, wherein the shape is rectangular or oblong.

18. The hot runner of claim 15, wherein the width of the channel is between about three and about ten times greater than height of the channel.

19. The hot runner channel of claim 15, wherein the hot runner has more than one portion.

20. The hot runner channel of claim 19, wherein the hot runner has a first receiving portion and a second shearing portion, wherein the first receiving portion and the second receiving portion are a first receiving portion are connected by a joining segment

20. The hot runner of claim 15, housed within a hot runner assembly or injection molding system.

21. A polymer preform having a controlled amount of stress and molecular orientation.

22. The polymer preform of claim 21 , wherein the polymer preform has a relative orientation index of about 1.2 to about 1.6.

23. The polymer preform of claim 21 , wherein the polymer comprises one or more thermoplastic polymers.

24. The polymer preform of claim 21, wherein the polymer comprises one or more polyesters.

25. The polymer preform of claim 21, wherein the polymer comprises polyethylene terephthalate.

26. The polymer preform of claim 20, wherein the polymer comprises a polyethylene terephthalate copolyester.

27. A beverage container made from the polymer preform of claim 21.

28. A beverage bottle made from the polymer preform of claim 21.

29. A method of forming a polymer container, comprising: (i) providing a polymer preform having a controlled amount of stress and molecular orientation and (ii) stretch blow molding the preform to produce a polymer container.

30. The method of claim 29, wherein the polymer container is a beverage container.

31. The method of claim 29, wherein the polymer container is a bottle.

32. The method of claim 29, wherein the polymer comprises one or more polyesters.

33. The method of claim 29, wherein the polymer comprises polyethylene terephthalate.

34. The method of claim 29, wherein the polymer preform has a relative orientation index of about 1.2 to about 1.6.

35. A packaged beverage comprising a container body having an outer surface and an interior space, wherein the container body is formed by blow molding a polymer preform having a controlled amount of stress and molecular orientation.

36. The packaged beverage of claim 33, wherein the polymer preform has a relative orientation index of about 1.2 to about 1.6.

37. The packaged beverage of claim 35, selected from a juice, a water or a carbonated beverage.