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Title:
BLENDED-MATERIALS BARRIER PACKAGING WALL WITH SUBSTANTIALLY REDUCED PEARLESCENCE AND HAZE
Document Type and Number:
WIPO Patent Application WO/2006/138636
Kind Code:
A1
Abstract:
The invention concerns compositions capable of scavenging oxygen which contain poly(ethylene terephthalate) base polymer and a nylon polymer. The compositions are formulated to provide improved clarity over current commercial products.

Inventors:
GOVINDARAJAN VENKAT (US)
Application Number:
PCT/US2006/023603
Publication Date:
December 28, 2006
Filing Date:
June 14, 2006
Export Citation:
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Assignee:
CONSTAR INT INC (US)
GOVINDARAJAN VENKAT (US)
International Classes:
A22C13/00; B29C65/00; B29D22/00; B29D23/00; B32B1/08; B32B27/10; B32B27/32; C08F283/00; C08G18/42; C08G63/91; C08G69/26; C08G69/48; C08J3/00; C08K3/10; C08L51/00; C08L67/00; C08L77/00; F16L11/04; H01M8/12
Foreign References:
US5281360A1994-01-25
Attorney, Agent or Firm:
Heist, Dale M. (2929 Arch Street - Suite 1200 Philadelphia, PA, US)
Fullmer, Harold A. (One Liberty Place - 46th Floor Philadelphia, PA, US)
Download PDF:
Claims:
What is claimed:
1. A composition capable of scavenging oxygen comprising: — a nylon polymer; — poly(ethylene terephthalate); and — a transition metal in the positive oxidation state; wherein the intrinsic viscosity of the nylon and the poly(ethylene terephthalate) differ by about 0.75 units or more, and the viscosity of the nylon does not exceed about 1.95 units.
2. The composition of claim 1 wherein the nylon polymer is MXD6.
3. The composition of claim 2 wherein the intrinsic viscosity of the MXD6 is from about 1.40 units to about 1.95 units.
4. The composition of claim 3 wherein the intrinsic viscosity of the poly(ethylene terephthalate) is from about 0.70 units to about 0.86 units.
5. The composition of claim 1 wherein the transition metal is cobalt in the +2 oxidation state and the cobalt is present in an amount of between about 10 and about 300 ppm based on the concentration of cobalt in composition.
6. The composition of claim 5 where at least a portion of said nylon is present as dispersed phases within the poly(ethylene terephthalate) and said dispersed phases being from about 0.3 to about 2 microns in size.
7. The composition of claim 1 wherein the poly(ethylene terephthalate) comprises about 2.5 to about 6 mole % comonomer based on the glycol content of the poly(ethylene terephthalate).
8. A method of improving clarity in an oxygen scavenging barrier containing nylon polymer, and poy(ethylene terephthalate) polymer, and at least one transition metal in the positive oxidation state, said method comprising using nylon and poly(ethylene terephthalate) polymers whose intrinsic viscosity differs by about 0.75 units or more, and where the viscosity of the nylon does not exceed about 1.95 units.
9. The method of claim 8 wherein the nylon polymer is MXD6 and the intrinsic viscosity of the MXD6 is from about 1.50 units to about 1.80 units.
10. The method of claim 9 wherein the intrinsic viscosity of the poly(ethylene terephthalate) is from about 0.70 units to about 0.80 units.
11. The method of claim 10 wherein at least a portion of said nylon is present as dispersed phases within the poly(ethylene terephthalate) and said dispersed phases have an average particle size of about 0.4 to about 0.8 micron.
12. An article or preform containing a composition comprising: — a nylon polymer; and ~ poly(ethylene terephthalate); wherein at least a portion of said nylon is present as dispersed phases within the poly(ethylene terephthalate) and said dispersed phases have an average particle size of about 0.4 to about 0.8 micron.
13. The article or preform formed from the composition of claim 12 wherein the nylon polymer is MXD6.
14. The article or preform formed from the composition of claim 13 wherein the average particle size of the MXD6 is about 0.5 to 0.7 micron.
15. An article or preform formed from a composition capable of scavenging oxygen; said composition comprising: — a nylon polymer; — poly (ethylene terephthalate); and — a transition metal in the positive oxidation state; wherein at least a portion of said nylon is present as dispersed phases within the poly(ethylene terephthalate) and said dispersed phases have an average particle size of about 0.4 to about 0.8 micron.
16. The article or preform of claim 15 wherein the nylon polymer is MXD6.
17. The article or preform of claim 15 wherein the average particle size of the MXD6 is about 0.5 to about 0.7 micron.
18. The article or preform of claim 15 wherein the transition metal is cobalt in the +2 oxidation state.
19. The article or preform of claim 15 wherein the transition metal is present in an amount of between about 10 and about 300 ppm based on the concentration of transition metal in the composition.
20. The article or preform of claim 15 wherein the transition metal is present in an amount of between about 100 and about 300 ppm based on the concentration of transition metal in the composition.
21. The article or preform of claim 15 wherein the composition comprises all or a part of the wall of a package for food, beverage, cosmetics, pharmaceuticals, or personal care products.
22. The article or preform of claim 21 wherein the package is a bottle or a closure for a bottle.
23. The article or preform of claim 22 wherein the bottle or closure is a monolayer construction.
24. The article or preform of claim 22 wherein the bottle or closure is a multilayer construction.
Description:
BLENDED-MATERIALS BARRIER PACKAGING WALL WITH SUBSTANTIALLY REDUCED PEARLESCENCE AND HAZE

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This invention claims benefit of U.S. Application No. 60/723,119 filed October 3, 2005 and U.S. Application No. 60/690,777 filed June 15, 2005. The disclosure of each is included herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates to polyester/polyamide blends having excellent gas barrier properties. More particularly, the present invention relates to physical blends of oxygen scavenging polyamide polymers with polyester polymers and having greatly improved appearance over those obtainable by the known art.

BACKGROUND OF THE INVENTION

[0003] It is known in the art to include an oxygen scavenger in the walls and components of packaging for the protection of oxygen sensitive package contents. Such scavengers are believed to react with oxygen that is trapped in the package or that permeates from outside of the package, thus extending the life of package contents. These packages include films, bottles, containers, and the like. Food, beverages (such as beer, wine, and fruit juices), cosmetics, medicines, and the like are particularly sensitive to oxygen exposure and require high barrier properties to oxygen to preserve the freshness of the package contents and avoid changes in flavor, texture, vitamins, and color.

[0004] Use of certain polyamides in combination with a transition metal is known to be useful as the oxygen scavenging material. One particularly useful polyamide is MXD6 which contains meta-xylylene moieties in the polymer chain. See, for example, U.S. Patent Nos. 5,639,815; 5,049,624; and 5,021,515. Polymers containing unsaturated olefins are also useful as scavengers See, for example, U.S. Patent Nos. 5,639,815 and 6,569,506.

[0005] Other, non-polymeric oxygen scavengers include potassium sulfite (U.S. Patent No. 4,536,409), unsaturated hydrocarbons (U.S. Patent No. 5,211,875), and ascorbic acid derivatives (U.S. Patent No. 5,075,362).

[0006] In barrier layers of packaging walls that are made from blends of polymeric oxygen scavenging materials, such as MXD6 polyamide, with base polymer resins, such as polyethylene terephthalate (PET), undesirable haziness and pearlescence can result. These undesirable properties are believed to be due to such factors as: (i) the immiscibility of the scavenging materials with the base polymer resins; (ii) the inability to create by mechanical blending means disperse-phase domains that are so small as not to interfere with the passage of light there through; (iii) refractive index differences between the blended components that arise or are exacerbated upon stretching, (for example, blends of PET and MXD6 polyamide, possibly microcrazing at particle boundaries between the materials); and (iv) the dispersed- phase scavenging material causing premature crystallization of PET base resin. One approach to minimizing such haze is to use compositions that serve as compatibilizers to reduce haze This approach, however, adds cost to the packaging material, and the compatibilizer is an additional material that must be evaluated for its suitability for contact with food. There is therefore a need in the art for barrier materials which provide high oxygen scavenging capability and are substantially transparent without use of the aforementioned measures.

SUMMARY OF THE INVENTION

[0007] In some aspects, the invention concerns a composition comprising:

— a nylon polymer;

— poly(ethylene terephthalate); and

— a transition metal in the positive oxidation state; wherein the intrinsic viscosity of the nylon and the poly(ethylene terephthalate) differ by about 0.75 units or more, and the viscosity of the nylon does not exceed about 1.95 units when measured by the standard solution intrinsic viscosity (IV) technique used for PET

(60:40 phenol / tetrachloroethane solvent system). In some preferred embodiments, the IV of the nylon is higher than that of the poly(ethylene terephthalate).

[0008] In some preferred embodiments, the composition is capable of scavenging oxygen. In some embodiments, the nylon polymer is MXD6. In certain embodiments, the intrinsic viscosity of the MXD6 is from about 1.40 units to about 1.95 units. In other embodiments, the intrinsic viscosity is from about 1.50 units to about 1.80 units. In still other embodiments, the intrinsic viscosity is from about 1.50 to about 1.70 units.

[0009] The intrinsic viscosity of the poly(ethylene terephthalate) is typically from about 0.70 units to about 0.86 units in some compositions. In certain embodiments, the intrinsic viscosity of the PET is about 0.70 to about 0.80 units.

[0010] In some embodiments, the poly(ethylene terephthalate) (commonly referred to as PET) has about 2.5 to about 6 mole % based on the glycol content of the PET. In certain embodiments, the PET has 4 to about 6 mole % co-monomer based on the glycol content of the PET. In other embodiments, the percent co-monomer is from about 4.5% to 5.8 mole %. In certain embodiments, the co-monomer is cyclohexane dimethanol (CHDM).

[0011] In some compositions, the transition metal is cobalt in the +2 oxidation state. Some compositions have the transition metal is present in an amount of between about 10 and about 300 ppm. Certain of these compositions have the transition metal present in an amount of between about 100 and about 300 ppm.

[0012] The invention also concerns articles and performs that comprise the compositions of the invention.

[0013] In some performs, at least a portion of the nylon is present as a dispersed phase with the base polymer (PET, for example). In some preferred embodiments, over half or substantially all of the nylon is present as dispersed phases. In some performs, the size of the dispersed phase (nylon) is at least 0.3 micron. In other embodiments, the size of the dispersed phase is equal to or greater than 0.4, or 0.5, or 0.6, or 0.7 or 0.8, or 0.9, or 1 micron. In some embodiments, the size of the dispersed phase is equal to or less than 2 microns. In other embodiments, the size of the dispersed phase is equal to or less than 1.5 or 1.0 microns.

[0014] In some preferred embodiments, the nylon is present as dispersed phases within the poly(ethylene terephthalate) and at least 90% of the dispersed phases being from about 0.3 to about 3 microns in size. In some embodiments, the average dispersed phase size is about 0.4 to about 0.8 micron. In other embodiments, the average dispersed phase size is about 0.5 to about 0.7 micron. In still other embodiments, the average dispersed phase size is about 0.55 to about 0.65 micron. The sizes are preferably average particles sizes measured

while the combination is an unstretched solid article, such as a preform prior to stretch blow molding or the finish portion of a blow-molded container.

[0015] In some aspects, the invention relates to the aforementioned compositions that are in a layer that is part of a wall of a package or closure for food, beverage, cosmetics, pharmaceuticals, or personal care products. Some layers are in packaging wall or closure wall having more than one layer. Other layers are part of a packaging wall or closure wall that is a monolayer.

[0016] The invention also concerns methods of improving appearance clarity of articles made from in an oxygen scavenging barrier containing a composition of the instant invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Certain embodiments of the invention are illustrated by Figures.

[0018] Figure 1 shows the effect of PET intrinsic viscosity on the size of dispersed phase.

[0019] Figure 2 shows nylon dispersion with two different nylon grades dispersed in low IV PET.

[0020] Figure 3 shows nylon dispersion with two different nylon grades dispersed in high IV PET.

[0021] Figure 4 shows pearlescence and haze measurements of 46 oz containers.

[0022] Figure 5 shows pearlescence and haze measurements of 36 oz containers.

[0023] Figures 6 and 7 show the impact of PET IV on dispersion.

[0024] Figure 8 shows the effect of dispersion on OTR performance.

[0025] Figure 9 shows differences in nylon dispersion as a function of composition.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0026] The present invention concerns compositions that are useful in the manufacture of walls and components of packaging for oxygen sensitive materials. In some embodiments, the invention concerns a polyester polymer composition, preforms, and blow molded containers with good oxygen scavenging properties as well as substantially reduced haze compared to current commercial PET compositions containing an oxygen scavenger comprised of MXD6 nylon.

[0027] In some embodiments, the present invention is directed at improving the visual / aesthetic appeal of a PET / MXD6 blend bottle. Typically, mono-layer MXD6 blend bottles made of a mechanical blend of MXD6 and PET and in the absence of a compatibilizer

can have increased haze as well as pearlescence or opalescence (bluish sheen) which makes them visually unattractive. Improving the visual appearance of the mono-layer MXD6 blend bottle is significant for the commercial appeal of such products.

[0028] In the present invention, the improvement in clarity /pearlescence is believed to be achieved by manipulating size of the dispersed phase (nylon) in the PET matrix. Clarity relates to the absence of haze. Pearlescence concerns the presence or absence of a bluish sheen. Results have shown that particle size of the dispersed phase in the preform molding process has a significant effect on the haze and opalescence seen in the containers. The size of the dispersed phase can be controlled by appropriate manipulation of the viscosity ratio of PET and nylon and, to some extent, processing during injection molding of performs which is an intermediate stage from which the final article is made by blow-molding. The morphology of the dispersed phase in the blown container is affected by the particle size of the dispersed phase in the injection molded preform as well as the intrinsic viscosity (IV) of PET (modulus of PET matrix) and blow molding process conditions. The amount of stress involved during blow molding depends on the following factors: IV of PET, stretching speed, preform temperature and planar stretch ratio.

[0029] The dispersion of nylon in PET also affects oxygen scavenging, as the contact area plays a part in the scavenging reaction. Thus, careful selection of nylon and PET (IV or molecular weight) is critical in achieving the balance between clarity and oxygen scavenging to produce a functional and attractive container.

[0030] While there has been much study on the development of haze in the containers, there is still not a single quantifying method for the see-through ability or clarity of a container. Several factors can contribute to haze in the container - surface imperfections, fluctuations in refractive index causing bending of light, etc. In the case of immiscible polymer blends, the dispersed phase can also serve as scattering centers resulting in significant scattering of light. In PET-nylon blend system, part of the haze is believed to be due to the inherent differences in refractive index between PET and nylon. Table 1 below gives the refractive index values of both oriented (stretched 3 x 3) and unoriented PET and MXD-6 (Source: Mitsubishi Gas Chemical Company, Japan).

Table 1. Refractive Index of MXD6 and PET.

where nx, ny, and nz refer to refractive indices in x, y and z directions. Typically, x and y represent the plane (axial and transverse) and z thickness direction.

[0031] It can be seen that while the refractive index of amorphous PET and nylon are close to each other. The refractive index of PET, however, increases substantially upon orientation by stretching, while that of nylon increases only slightly. It is believed that in order to minimize haze, the critical delta (difference in refractive indices of the two phases) must not be greater than 0.01. It appears that some scattering effect occurs in blow-molded PET-nylon blend containers due to this mismatch in refractive index as considerable orientation also occurs during the blowing process. The aspect ratio of the dispersed phase particles is also believed to increase during the stretching process thus increasing the potential for haze.

[0032] While not wanting to be bound by theory, it is believed that several factors influence the overall appearance in the container. These factors include:

• size of the dispersed phase particles in the preform (after injection molding);

• size and aspect ratio of the dispersed phase particles in the bottle (after stretching);

• phase separation occurring during stretching with possible creation of imperfections such as chain rupture, cracks and voids at the interface;

• surface texture affecting light reflection / refraction at the surface;

• refractive index differences between the matrix and dispersed phase - both in the amorphous and the oriented states; and

• formation of crystalline structure during re-heating of the preform in the blow molding stage.

[0033] As used herein, the term "size" when referring to a dispersed phase means the largest dimension of the phase. In many embodiments, the dispersed phase is spherical but some are elongated due to flow extension.

[0034] The size of the dispersed phase in the preform as-made would be determined by the viscosity ratio (p) of the dispersed phase and the matrix as well as shear imparted during processing. Higher the melt viscosity of the dispersed phase compared to the matrix, less shear will be imparted to the dispersed phase resulting in larger size of the dispersed phase. The relationship between the viscosity ratio, shear and the dispersed phase size is given by the following relationship:

D = 4 p +α84 r/Gη m for p>l and

D = 4 p-°- 84 r/Gη m for p<l where G is shear rate, D = average particle diameter, r = interfacial tension, p = viscosity ratio and η m = viscosity of the matrix.

[0035] The size of the dispersed phase in the injection molded perform as-made can be controlled by selecting appropriate viscosity ratio (p), viscosity of the matrix and shear. The size of the dispersed phase influences the type of scattering that would occur. It is known that in the case of microheterogeneous blends, in order to maintain transparency the critical particle size should be less than 0.1 microns. If the particle size is of the order of wavelength of light, we get the phenomenon of Rayleigh scattering with the scattered light being in the lower wavelength range (blue).

[0036] During the stretch blow molding process, the preform is re-heated to above PET' s glass transition temperature and biaxially stretched to give a blow -molded container. Blowing process involves considerable stress on the plastic resulting in the development of strain-induced crystallinity as well as amorphous orientation. The aspect ratio of the dispersed phase increases with the shape changing from spherical droplets to ellipse to a lamellar plate like structure. The amount of stress imparted during the blowing process would depend on the IV of the PET matrix, the stretching speed, the blow temperature as well as the stretch ratio.

[0037] The contribution to haze from the blowing process can be identified to two sources:

~ increase in aspect ratio of the dispersed phase and

— the mismatch in refractive index of PET and nylon on account of stretching. We believe that this increase in the size of the dispersed phase can be limited by careful selection of PET and nylon molecular weight. When the molecular weight of the dispersed phase (nylon) is substantially higher compared to the molecular weight of the matrix (PET), it is believed that the stress acting on the dispersed phase will not be sufficient to cause it to

stretch. It is also possible that this will prevent some of the chain ruptures / voids occurring at the phase interface.

[0038] It is suggested that when the IV of PET is low relative to that of the MXD6, that when there is substantial difference in the molecular weight between the dispersed phase the matrix, the amount of stress acting on the dispersed phase might not be high enough to stretch the dispersed phase sufficiently enough to cause scattering. This hypothesis theory can be substantiated by two other indirect measures - oxygen transmission and brittle failure on drop. It has been observed that when the viscosity ratio (p) is high, bottles show good transparency as described earlier. This is attributed to the larger size of the dispersed phase during injection molding and less of orientation / stretching of the dispersed phase during the subsequent blow molding step. It is known that the contact area of the dispersed phase would play a role in scavenging. If the dispersed phase is not stretched enough, it would reduce the area available for the scavenging reaction to take place with the in-coming oxygen. This, in some cases, can affect OTR performance depending on bottle design and material distribution.

[0039] It has also been observed that the drop impact performance is affected by the dispersion quality. It is speculated that the larger size of the dispersed phase affects how the stress is transferred through the matrix. With a finer dispersion, the blend behaves essentially as a single-phase system with respect to responding to applied stress. With higher size of the dispersed phase, the load will not be transferred through the matrix uniformly resulting in a tendency toward brittle behavior. Following table illustrates the effect on drop impact performance of 16 oz hot-fill containers. 12 bottles of each variable were filled with water and dropped from a height of 6' both vertical (impact on the base) and horizontal (side-panel) manner.

Table 2.

where MFI is Melt Flow Index - a measure of melt viscosity.

[0040] In Table 3, Dispersion Quality is graded on a scale of 0 to 4 with 0 being poor and 4 being excellent. HB is Holcobatch, a product of Holland Colours that is a carrier used to incorporate the cobalt catalyst. 6007 and 6121 are commercially available grades of MXD6 resin. Low IV PET (Precursor - 0.63 IV), PET-A, and PET-B are commercially available PET compositions from Voridian division of Eastman Chemical.

Table 3.

[0041] The intrinsic viscosity values described throughout this description are set forth in dL/g units as calculated from the inherent viscosity measured at 25 0 C in a 60/40 wt/wt phenol/tetrachloroethane solvent system using the solution IV method typically used in polyester industry (see ASTM D 2857 for details).

[0042] Use of certain polyamides in combination with a transition metal is known to be useful as the oxygen scavenging material. One particularly useful polyamide is MXD6 which contains meta-xylene residues in the polymer chain. See, for example, U.S. Patent Nos. 5,639,815; 5,049,624; and 5,021,515. MXD6, produced by the condensation of meta- xylenediamine (MXDA) and adipic acid, can be obtained commercially from Mitsubishi Gas Chemical Company.

[0043] In some embodiments, commercial MXD6 can be solid stated to produce a product with an IV of about 1.4 to about 1.95. In some embodiments, a product with an IV of about 1.5 to about 1.8 is produced. Some data suggests that products made with an IV higher than about 1.95 or higher can cause the final product to be brittle as measured by drop tests.

[0044] Compositions of the instant invention comprise a base polymer. In some embodiments, the base polymer is a polyester. In certain embodiments, the polyester polymers of the invention are thermoplastic and, thus, the form of the compositions are not limited and can include a composition in the melt phase polymerization, as an amorphous pellet, as a solid stated polymer, as a semi-crystalline particle, as a composition of matter in a melt processing zone, as a bottle preform, or in the form of a stretch blow molded bottle or other articles. In certain preferred embodiments, the polyester is polyethylene terephthalate (PET).

[0045] Particularly suitable polyester polymers include polyethylene terephthalate homopolymers and copolymers modified with one or more polycarboxylic acid modifiers in a cumulative amount of less than about 15 mole %, or about 10 mole % or less, or about 8 mole % or less, or one or more hydroxyl compound modifiers in an amount of less than about 60 mol %, or less than about 50 mole %, or less than about 40 mole %, or less than about 15 mole %, or about 10 mole % or less, or about 8 mole % or less (collectively referred to for brevity as "PET"). The preferred polyester polymer is polyalkylene terephthalate, and most preferred is PET.

[0046] The polyester compositions can be prepared by polymerization procedures known in the art sufficient to effect esterification and polycondensation. Polyester melt phase manufacturing processes include direct condensation of a dicarboxylic acid with the diol, optionally in the presence of esterification catalysts, in the esterification zone, followed by polycondensation in the prepolymer and finishing zones in the presence of a polycondensation catalyst; or ester exchange usually in the presence of a transesterification catalyst in the ester exchange zone, followed by prepolymerization and finishing in the presence of a polycondensation catalyst, and each may optionally be solid stated according to known methods.

[0047] The transition metal used in the instant compositions is a metal in the positive oxidation state. It should be noted that it is contemplated that one or more such metals may be used. In some embodiments, cobalt is added in +2 or +3 oxidation state. In some embodiments, it is preferred to use cobalt in the +2 oxidation state. In certain embodiments, copper in the +2 oxidation state is utilized. In some embodiments, rhodium in

the +2 oxidation state is used. In certain embodiments, zinc may also be added to the composition. Preferred zinc compounds include those in a positive oxidation state.

[0048] Suitable counter-ions to the transition metal cations include carboxylates, such as neodecanoates, octanoates, acetates, lactates, naphthalates, malates, stearates, acetylacetonates, linoleates, oleates, palmitates, 2-ethylhexanoates, or ethylene glycolates; or as their oxides, borates, carbonates, chlorides, dioxides, hydroxides, nitrates, phosphates, sulfates, or silicates among others.

[0049] In some embodiments, levels of at least about 10 ppm, more preferably at least about 50 ppm, still more preferably at least about 100 ppm of metal can achieve suitable oxygen scavenging levels. The exact amount of transition metal used in an application can be determined by trials that are well within the skill level of one skilled in the art. In some embodiments involving wall applications (as opposed to master batch applications where more catalyst is used), it is preferred to keep the level of metal below about 300 ppm and, in other embodiments, preferably below about 250 ppm.

[0050] The amount of each metal is expressed in ppm based on the metal, not based on the metal salt as added. The amount of metal may be measured by X-ray fluorescence (X- Ray) or Inductively Coupled Plasma — Mass Spectrometry (ICP). It should be further noted that the ppm of metal is based on the concentration of the metal in the entire composition which includes nylon polymer, poly(ethylene terephthalate), and any optional ingredients that may be in the composition.

[0051] The instant invention may also be applied to master batch composition. These compositions are concentrated compositions that can be diluted in a suitable base polymer for use in forming a barrier. In master batch compositions, the level of transition metal may range from about 1000 to about 10,000 ppm. In some preferred embodiments, the range is from about 2000 to about 5000 ppm

[0052] The transition metal or metals may be added neat or in a carrier (such as a liquid or wax) to an extruder or other device for making the article, or the metal may be present in a concentrate or carrier with the oxidizable organic component, in a concentrate or carrier with a base polymer, or in a concentrate or carrier with a base polymer/oxidizable organic component blend. Alternatively, at least a portion of the transition metal may be added as a polymerization catalyst to the melt phase reaction for making the base polymer (a polyester polymer in some embodiments) and be present as residual metals when the polymer is fed to the melting zone (e.g. the extrusion or injection molding zone) for making the article such as a preform or sheet. It is desirable that the addition of the transition metal does not

substantially increase the intrinsic viscosity (It. V) of the melt in the melt processing zone. Thus, transition metal or metals may be added in two or more stages, such as once during the melt phase for the production of the polyester polymer and again once more to the melting zone for making the article.

[0053] Other additional components are well known to those skilled in the art and can be added to the existing composition so long as they do not negatively impact the performance of the compositions. Typically, the total quantity of such components will be less than about 10% by weight relative to the whole composition. In some embodiments, the amount of these optional components is less than about 5%, by weight relative to the total composition.

[0054] A common additive used in the manufacture of polyester polymer compositions used to make stretch blow molded bottles is a reheat additive because the preforms made from the composition must be reheated prior to entering the mold for stretch blowing into a bottle. Any of the conventional reheat additives can be used, such additives include various forms of black particles, e.g. carbon black, activated carbon, black iron oxide, glassy carbon, and silicon carbide; the gray particles such as antimony, and other reheat additives such as silicas, red iron oxide, and so forth.

[0055] In many applications, not only are the packaging contents sensitive to the ingress of oxygen, but the contents may also be affected by UV light. Fruit juices and pharmaceuticals are two examples of such contents. Accordingly, in some embodiments, it is desirable to incorporate into the polyester composition any one of the known UV absorbing compounds in amounts effective to protect the packaged contents so long as the compounds do not negatively impact performance.

[0056] The instant compositions can be made, for example, by mixing a base polymer (PET, for example) with the oxidizable organic component (a nylon) and the transition metal composition. Such compositions can be made by any method known to those skilled in the art. In certain embodiments, some or part of the transition metal may exist in the base polymer prior to mixing. This residual metal, for example, can exist from the manufacturing process of the base polymer. In some embodiments, the base polymer, the oxidizable organic component and the transition metal are mixed by tumbling in a hopper. Other optional ingredients can be added during this mixing process or added to the mixture after the aforementioned mixing or to an individual component prior to the aforementioned mixing step.

[0057] The instant composition can also be made by adding each ingredient separately and mixing the ingredients prior melt processing the composition to form an article. In some embodiments, the mixing can be just prior to the melt process zone. In other embodiments, one or more ingredients can be premixed in a separate step prior to bringing all of the ingredients together.

[0058] In certain embodiments, when the instant compositions are used in a wall or as a layer of a wall, the permeability of the composition for oxygen is advantageously not more than about 3.0, or about 1.7, or about 0.7, or about 0.2, or about 0.03 cm 3 mm/(m 2 atm day). The permeability of the composition provided by the present invention is advantageously not more than about three-quarters of that in the absence of oxygen- scavenging properties. In some embodiments, the permeability is not more than about one half, one-tenth in certain embodiments, one twenty-fifth in other embodiments, and not more than one-hundredth in yet other embodiments of that in the absence of oxygen-scavenging properties. The permeability in the absence of oxygen-scavenging properties is advantageously not more than about 17 cm 3 mm/(m 2 atm day), or about 10, and or about 6. A particularly good effect can be achieved for such permeabilities in the range from about 0.5, or about 1.0, to 10, or about 6.0 cm 3 mm/(m 2 atm day). Measurements of oxygen permeation can be made by methods described, for example, in U.S. Patent No. 5,639,815, the contents of which are incorporated herein in its entirety.

[0059] In another aspect, the instant composition can be used as a master batch for blending with a polymer or a polymer containing component. In such compositions, the concentration of the oxidizable organic component and the transition metal will be higher to allow for the final blended product to have suitable amounts of these components. The master batch may also contain an amount of the polymer with which the master batch is to be blended with. In other embodiments, the master batch may contain a polymer that is compatible with the polymer that the master batch is to be blended with.

[0060] In yet another aspect, the compositions of the instant invention can be used for forming a layer of a wall which primarily provides oxygen-scavenging (another layer including polymer providing gas barrier without significant scavenging), or as a head-space scavenger (completely enclosed, together with the package contents, by a package wall). Such techniques are well known to those skilled in the art.

[0061] The time period for which the permeability is maintained can be extended by storing the articles in sealed containers or under an inert atmosphere such as nitrogen prior to use with oxygen sensitive materials. Such a scheme may prove beneficial where performs or

rolls of film or sheet are to be stored for long periods prior to further packaging-conversion operations.

[0062] In another aspect, the invention provides a package, whether rigid, semirigid, collapsible, lidded, or flexible or a combination of these, comprising a wall as formed from the compositions described herein. Such packages can be formed by methods well known to those skilled in the art.

[0063] Among the techniques that may be used to make articles are moulding generally, injection moulding, stretch blow moulding, extrusion, thermoforming, extrusion blow moulding, and (specifically for multilayer structures) co-extrusion and lamination using adhesive tie layers. Orientation, e.g. by stretch blow moulding, of the polymer is especially attractive with phthalate polyesters because of the known mechanical advantages that result.

[0064] Specific articles include preforms, containers and films for packaging of food, beverages, cosmetics, pharmaceuticals, and personal care products where a high oxygen barrier is needed. Examples of beverage containers for which the instant invention are particularly useful are bottles for containing juices, sport drinks, beer or any other beverage where oxygen detrimentally affects the flavor, fragrance, performance (prevent vitamin degradation), or color of the drink. The compositions of the instant invention are also particularly useful as a sheet for thermoforming into rigid packages, and as films for flexible- package structures. Rigid packages include food trays and lids. Examples of food tray applications include dual ovenable food trays, or cold storage food trays, both in the base container and in the lidding (whether a thermoformed lid or a flexible film), where the freshness of the food contents can decay with the ingress of oxygen. The compositions of the instant invention also find use in the manufacture of cosmetic containers and containers for pharmaceuticals or medical devices.

[0065] The package walls of the instant invention can be a single layer or a multilayer constructions. In some embodiments using multilayer walls, the outer and inner layers may be structural layers with one or more further layers. Any of the layers may contain the oxygen scavenging material of this invention. In the most-preferred embodiments, a single layer design is preferred. Such a design may have advantages in simplicity of manufacture and cost, without sacrifice of the transparency of the polyester base polymer.

[0066] As used herein, the terms "a", "an", "the" and the like refer to both the singular and plural unless the context clearly indicates otherwise. "A bottle", for example, refers to a single bottle or more than one bottle.

L0U67J Also as used herein, the description of one or more method steps does not preclude the presence of additional method steps before or after the combined recited steps. Additional steps may also be intervening steps to those described. In addition, it is understood that the lettering of process steps or ingredients is a convenient means for identifying discrete activities or ingredients and the recited lettering can be arranged in any sequence.

[0068] Where a range of numbers is presented in the application, it is understood that the range includes all integers and fractions thereof between the stated range limits. A range of numbers expressly includes numbers less than the stated endpoints and those in- between the stated range. A range of from 1-3, for example, includes the integers one, two, and three as well as any fractions that reside between these integers.

[0069] As used herein, "master batch" refers to a mixture of base polymer, oxidizable organic component, and transition metal that will be diluted, typically with at least additional base polymer, prior to forming an article. As such, the concentrations of oxidizable organic component and transition metal are higher than in the formed article.

[0070] As used herein, the term "combining" includes blending or reacting the components that are combined.

Examples

[0071] The instant invention is illustrated by the following examples that are not intended to limit the scope of the invention.

Example 1: Effect of PET IV on size of dispersed phase

[0072] 16 oz stock H.F preforms were injection molded on LX160 PET Husky machine equipped with 2-cavity mold. The dispersion of nylon in PET was determined using standard SEM technique. The samples were cut from the finish area of the preform. The samples were freeze fractured after immersion in liquid nitrogen, etched 20 seconds in 50°C / 122 0 F formic acid and gold coated. SEM photographs were taken at approximately 500x and 200Ox on samples cut from the finish area. The results can be seen in SEM photographs presented in Figure 1.

Example 2: Effect of Nylon IV

[0073] Examples below compare the effect of two grades of nylon - 6121 and 6007 on the size of the dispersed phase with both Low and High IV PET. The results can be seen in

SEM photographs presented in Figures 2 and 3. It can be seen that with low IV PET, the difference in the size of the dispersed phase changes significantly with the grade of nylon used. It can also be seen that with high IV PET, the difference in dispersion quality with the two grades of nylon diminishes as the shear imparted to the dispersed phase is high because of the higher melt viscosity of PET. This is consistent with the theory that the viscosity of the PET matrix controls the amount of shear imparted to the dispersed phase in the extrusion process.

Example 3: Haze/Optical Data

[0074] Opalescence and % Haze measurement: Opalescence is measured using a device that measures the surface sheen (bluish sheen) seen on the bottle surface. Light is shined on the sample at an angle and reflected light is measured by the detector at 45° angle from the sample surface. % Haze is measured using a Hunter Lab spectrophotometer. Following samples were measured from 46 oz container side-wall: l. PET

2. T6- PET-I (0.78 IV) + 1.5% 6007 HT (1.39 IV)+ 75 ppm Co

3. V2-1.5% - PET-2 (0.74 IV) + 1.5% 6121HT (1.50 IV) + 100 ppm Co

4. V2-2.0% - PET-2 (0.74IV) + 2.0% 6121HT (1.50 IV) + 100 ppm Co [0075] PET-I and PET-2 refer to PETs. 6007 and 6121 refer to MXD6. A

MXD6 composition designated HT is one that was solid stated to an IV of about 1.4 to about 1.8.

[0076] Haze data is presented in Table 4.

Table 4. Haze data.

[0077] It can be seen that with the new formulation (V2) both the pearlescence as well as the haze values are reduced. It is believed that the in the case of the V2 samples,

me higher particle size lead to reduction in both pearlescence and haze. The pearlescence values were measured for 36 oz bottles made with T6 and V2 formulation and shown in the graph in Figure 5.

Example 4: Effect of Dispersion on OTR

[0078] Three different PET IV compositions, Precursor (0.63 IV), Precursor SS (0.72 IV) and Heat wave (0.86 IV), were used to formulate barrier compositions with MXD6. SEM photos in Figures 6 and 7. I t can be seen that the dispersions become bigger as we go from Heat Wave (HW) to Precursor.

[0079] OTR for the precursor improves once precursor is solid stated to a 0.72 IV. The results are shown in Figure 8. It can be seen that as the dispersion improves and so does OTR.

Example 5 — Use of CHDM Co-monomer Containing PET

[0080] Samples made by blending PET-2 (0.76 IV) with 1.5% 6121 HT (IV 1.6 or greater) and PET Co masterbatch showed that the preforms displayed some brittleness. While not wanting to be bound by theory, it is believed that the brittle behavior was caused by the larger size of the dispersed phase (nylon). The bottles were clear and had less of bluish sheen that conventional performs but showed an increased failure rate in the drop test.

[0081] For the drop test, bottles were filled with water up to brimful capacity and were capped and dropped both vertically as well as horizontally from a height of 4 feet and any failures (leakage) were recorded

[0082] It was found that one way to improve the brittleness was to increase the copolymer content of PET. PET used for all the monoxbar trials had cyclohexane dimethanol (CHDM) as the co-monomer to varying amount. It is believed that increasing the co- monomer content would result in a softer material - the CHDM becoming part of the chain and disrupting the regularity and packing of PET chains thereby resulting in increased free volume. It is believed that this enables the chains to slide past each other when subjected to an impact and be able to absorb the energy without undergoing rupture.

[0083] Higher CHDM content was added into the PET being used for these tests by either selecting a PET resin having higher CHDM content or separately adding PETG with high CHDM content at different loadings to get the desired CHDM level in the preforms. It is believed that an added bonus for this modification is an improvement in the blow processing

of preforms because increasing CHDM level slows down the crystallization rate of PET and thereby allowing higher preform temperatures to be used while blowing bottles. Table 5 shows the different levels of CHDM present in the PET used for containers.

Table 5. Composition Table

[0084] 36 oz preforms were injection molded with nylons having three different IVs (6007HT- IV=1.40, 6121- IV=1.50 and 6121HT - IV=I.62). The preforms were injection molded using a standard Husky 300 ton injection molding machine equipped with a 48 cavity mold. SEM pictures of the finish were taken to look at differences in nylon dispersion as shown in Figure 9.

Example 6 — Drop Test

[0085] Preforms were manufactured on LX160 T machine with a 2 cavity 36 oz preform mold using the following formulation: PET-2 + 1.5% 6121 HT (CNS-2) + 2.5% PET Co MB.

[0086] The nylon IV was about 1.5 as tested using the solution method. Bottles were made on a Sidel SBO-I machine. They were filled with water and drop test was performed from 4' in both vertical (impact on base) as well as horizontal (impact on side wall/ finish) manner. Following are the results: Horizontal drop: 15 out of 16 bottles passed Vertical drop: 16 out of 16 bottles passed

Example 7- Drop Test

[0087] Preforms were made on SX500 PET machine equipped with a 48 cavity 36 oz preform mold using the following formulations:

Variable #1: PET-2 + 1.5% 6121 (IV: 1.50) + 2.5 % PET Co MB

Variable #4: PET-I + 10% PETG (6763) + 1.5% 6121HT (IV: 1.60) + 2.5% PET Co MB

Bottles were made on Line #66 SBO 16/20 blow molding machine and only horizontal drop test was performed.

Variable #1: Horizontal drop: 12 out of 15 bottles passed.

Variable #4: Horizontal drop: 15 out of 15 bottles passed.

Example 8 -Drop Test

[0088] Preforms were made on SX500 PET machine equipped with a 48 cavity 36 oz preform mold using the following formulations: Variable #5: PET-3 + 1.5% 6121HT (IV: 1.60) + 1.2 % PETG Co MB Variable #6: PET-3 + 1.5% 6121 (IV: 1.50) + 1.2% PETG Co MB Variable #7: PET-3 + 1.5% 6121 + 2.0% PET Co MB

Bottles were made on Line #66 SBO 16/20 blow molding machine and only horizontal drop test was performed.

Variable #5: Horizontal drop: 17 out of 17 bottles passed. Variable #6: Horizontal drop: 17 out of 17 bottles passed. Variable #7: Horizontal drop: 16 out of 17 bottles passed.

[0089] It is believed that, in some embodiments, the preferred CHDM level is 4.5% to 5.8% to reduce brittleness when using Nylon IV in the range of 1.55 to 1.65. This results in a scavenging bottle that is relatively clear and meets industry bottle performance requirements.

Example 9 - Determination of Dispersed Phase Size

[0090] Determination of particle size or dispersed phase size can be made using techniques well known to those skilled in the art. See, for example, an article titled Morphology and Properties of PET/PA-6/E-44 Blends published in the Journal of Applied Polymer Science Vol. 69 (1998) by Huang, Liu, and Zhao. This article outlines a procedure for preparing samples of PET/nylon blends for scanning electron microscope (SEM) examination, which involves etching freeze-fracture surfaces in 6O 0 C (122 0 F) formic acid prior to the SEM examination. The formic acid selectively attacks the nylon, leaving cavities in the PET where the nylon phase had been located.

[0091] As way of illustration, in the current invention, sections cut from molded sheet samples and the finish area of the 16-oz bottle samples were prepared for SEM examination as follows:

-- The samples were immersed in liquid nitrogen for 10 minutes, then immediately fractured. To fracture the sheet samples, two sets of pliers were used to bend the samples in half. Since the samples from the bottle finish area were too thick to fracture with pliers, they were placed in a vise, which was immediately cranked shut to cause a brittle fracture.

— The samples were dipped in 122 0 F formic acid for 20 seconds. This time was not necessarily optimized and other times may be used. It was noted that the samples exhibited a cloudy appearance after this treatment, which was interpreted as a sign that the formic acid had begun to have some type of effect on the samples.

— The samples were gold-coated, and the fracture surfaces were examined in the SEM.

— When samples prepared as outlined above were examined in the SEM, cavities similar to those illustrated in the journal article could be observed, and some differences were noted between the various samples. The nylon appeared to be more uniformly distributed in the molded sheet samples than in the bottle samples. The bottle samples exhibited a much wider range of nylon phase size than the sheet samples. The nylon phase in the sheet sample with the 6001 nylon exhibited an oval appearance, while the nylon phase in the other samples appeared spherical. It is not clear whether this is an effect of the molding operation. It was also noted that the distribution of the nylon in the sample with 150 ppm was less uniform than in the samples with 50 and 100 ppm cobalt.

Example 10- Determination of Dispersed Phase Size

[0092] Dispersed phase size analysis of the articles produced in Example 5 and shown in the SEM pictures of Figure 9 is reported in Table 6. Particle size was determined as described in Example 8. In Table 6, the average size is reported in microns. The "% of part" value is the percentage of particles with the listed particle size. "Cum %" is the percentage of particles with the listed particle size or less.

Table 6. Average Particle Size of the Dispersed Phase

6007 HT 6121 HT

Avg size % of part Avg size % of part Cum %

0 0

0.27 35.86 35.86 0.38 56.58 56.58

0.32 22.76 58.62 0.56 28.95 85.53

0.36 17.24 75.86 0.85 5.26 90.79

0.42 5.52 81.38 1.22 2.63 93.42

0.46 5.52 86.9 1.44 2.63 96.05

0.51 1.38 88.28 2.53 2.63 98.68

0.54 6.9 95.18 2.98 1.32 100

0.6 3.45 98.63

0.67 0.69 99.32

0.72 0.69 100.01

[0093] All patents, patent applications and publications described herein are incorporated by reference in their entirety.