Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/78—Preparation processes
  • C08G63/82—Preparation processes characterised by the catalyst used
  • C08G63/83—Alkali metals, alkaline earth metals, beryllium, magnesium, copper, silver, gold, zinc, cadmium, mercury, manganese, or compounds thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
  • C08K3/346—Clay
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K9/00—Use of pretreated ingredients
  • C08K9/04—Ingredients treated with organic substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2650/00—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
  • C08G2650/28—Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule characterised by the polymer type
  • C08G2650/34—Oligomeric, e.g. cyclic oligomeric
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/008—Additives improving gas barrier properties
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1334—Nonself-supporting tubular film or bag [e.g., pouch, envelope, packet, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
  • Y10T428/1352—Polymer or resin containing [i.e., natural or synthetic]
  • Y10T428/1397—Single layer [continuous layer]

Definitions

• the present invention is a method for reducing the permeability of gases through polyester containers and films by incorporating into the polymer from which the container or film is formed an effective amount of exfoliated sepiolite-type clay.
• Nanocomposites are polymers reinforced with nanometer sized particles, i.e., particles with a dimension on the order of 1 to several hundred nanometers.
• Polymer-layered silicate nanocomposites incorporate a layered clay mineral filler in a polymer matrix.
• Layered silicates are made up of several hundred thin platelet layers stacked into an orderly packet known as a tactoid. Each of these platelets is characterized by a large aspect ratio (diameter/thickness on the order of 100-1000). Accordingly, when the clay is dispersed homogeneously and exfoliated as individual platelets throughout the polymer matrix, dramatic increases in strength, flexural and Young's modulus, and heat distortion temperature are observed at very low filler loadings ( ⁇ 10% by weight) because of the large surface area contact between polymer and filler. In addition, barrier properties are greatly improved because the large surface area of the platelets greatly increases the tortuosity of the path a diffusing species must follow in permeating through the polymeric material.
• Clay minerals and their industrial applications are reviewed by H. M. Murray in Applied Clay Science 17 (2000) 207-221.
• Two types of clay minerals are commonly used in nanocomposites: kaolin and smectite.
• the molecules of kaolin are arranged in two sheets or plates, one of silica and one of alumina.
• the most widely used smectites are sodium montmorillonite and calcium montmorillonite.
• Smectites are arranged in two silica sheets and one alumina sheet.
• the molecules of the montmorillonite clay minerals are less firmly linked together than those of the kaolin group and are thus further apart.
• Nanocomposites have enjoyed increased interest since the initial development of nylon based material by Usuki et al. in 1993. (Usuki, A., et al., Journal of Materials Research, 1993.8 (5): p. 1179-1184.) Attempts to generate nanocomposites in a thermoplastic polyester matrix, however, have been only marginally successful. It is desirable to disperse and exfoliate clays in polyesters to enhance barrier properties, for example, in packaging applications. The majority of the polyester efforts focused on the development of polyesters with excellent barrier properties. These efforts focused on the use of smectites with a quaternary ammonium cation bearing an organic tail. This approach, while amenable to compounding methodologies, typically suffers because the exfoliating agent is not stable at the compounding temperatures. Furthermore, this route typically only results in the formation of tactoids or tactoid agglomerates in the polymer matrix.
• An alternative route to preparing nanocomposites is exfoliation through polymerization.
• This approach typically involves dispersing the nanofiller, us ⁇ ally a smectite like a montmorillonite, in one or more of the monomers and subsequently forming the polymer around the dispersion.
• One of the keys to successfully exfoliating the clay with this process involves selecting the proper intercalating agent.
• the interaction between the intercalating agent and the monomer must be sufficiently strong so that it is capable of driving the monomer into the galleries of the clay. Therefore, this process requires the use of an intercalating agent and as such introduces the same thermal stability issues described above.
• a third route employed in the preparation of polyester-based nanocomposites is the use of another polymer such as polyvinyl pyrrolidone) to facilitate the exfoliation of the clay into the polymer matrix.
• Nanocor® Inc. (Nanocor® Inc. is a wholly owned subsidiary of AMCOL International Corporation, Arlington Heights, Illinois.) and Eastman Chemical Company (Kingsport, Tennessee) have both employed this approach in the preparation of polyester-based nanocomposites for use in applications that require materials with excellent barrier properties and mechanical properties (see, e.g., U.S. Patent 5,698,624 to Nanocor® and PCT Int. Appl. WO 99/03914 to Eastman Chemical).
• this approach typically uses a solution-based process that allows the clay and polymer to interact and increase the basal spacing on the clays.
• the solvent is subsequently removed under vacuum, yielding an intercalated smectic clay system.
• the materials are then melt compounded with the desired polymer matrix (typically PET), extruded, and pelletized.
• the desired polymer matrix typically PET
• This approach suffers from the requirement to use a large amount of solvent.
• the polymer and clay represent only a small weight percent of the intercalation solution; see, e.g., Trexler Jr., J. W., Piner, R.L, Turner, S.R. and Barbee, R.B. PCT Int. Appl. WO 99/03914.
• a polymer e.g., polyvinyl pyrrolidone
• the method comprises the steps: a. preparing a polyester nanocomposite by mixing a sepiolite- type clay with at least one polyester precursor selected from the group
• the nanocomposite contains an effective amount of exfoliated sepiolite-type clay.
• an effective amount means that enough exfoliated sepiolite-type clay is present to cause a detectable decrease in the permeability of the article to the permeating substance of interest (e.g., oxygen). This is from 0.1 % by wt. to 20% by wt. of the polyester nanocomposite.
• PET film or injection stretch blow molded polyester
• nanocomposite or “polymer nanocomposite” means a polymeric material which contains particles, dispersed throughout the polymeric material, having at least one dimension in the 0.1 to 100 nm range (“nanoparticles").
• the polymeric material in which the nanoparticles are dispersed is often referred to as the "polymer matrix.”
• polyester composite refers to a nanocomposite in which the polymeric material includes at least one polyester.
• silicate-type clay refers to both sepiolite and attapulgite (palygorskite) clays.
• exfoliate literally refers to casting off in scales, laminae, or splinters, or to spread or extend by or as if by opening out leaves.
• exfoliation refers to the separation of platelets from the smectic clay and dispersion of these platelets throughout the polymer matrix.
• exfoliation or “exfoliated” means the separation of fiber bundles or aggregates into nanometer diameter fibers which are then dispersed throughout the polymer matrix.
• an effective amount means that enough barrier enhancing additive is present to cause a detectable decrease in the permeability of the article to the permeating substance of interest (e.g., oxygen). This is from 0.1% by wt. to 20% by wt. of the polyester nanocomposite.
• an alkylene group means -C n H 2n - where n ⁇ 1.
• a cycloalkylene group means a cyclic alkylene group, -C n H 2n - X -, where x represents the number of H's replaced by cyclization(s).
• a mono- or polyoxyalkylene group means
• an alicyclic group means a non-aromatic hydrocarbon group containing a cyclic structure therein.
• a divalent aromatic group means an aromatic group with links to other parts of the macrocyclic molecule.
• a divalent aromatic group may include a meta- or para-linked monocyclic aromatic group.
• polyyester means a condensation polymer in which more than 50 percent of the groups connecting repeat units are ester groups.
• polyesters may include polyesters, poly(ester-amides) and poly(ester-imides), so long as more than half of the connecting groups are ester groups.
• At least 70% of the connecting groups are esters, more preferably at least 90% of the connecting groups are ester, and especially preferably essentially all of the connecting groups are esters.
• the proportion of ester connecting groups can be estimated to a first approximation by the molar ratios of monomers used to make the polyester.
• PET means a polyester in which at least 80, more preferably at least 90, mole percent of the diol repeat units are from ethylene glycol and at least 80, more preferably at least 90, mole percent of the dicarboxylic acid repeat units are from terephthalic acid.
• polyester precursor means material which can be polymerized to a polyester, such as diacid (or diester)/diol mixtures, polymerizable polyester monomers, and polyester oligomers.
• polymerizable polyester monomer means a monomeric compound which polymerizes to a polymer either by itself or with other monomers (which are also present).
• Some examples of such compounds are hydroxyacids, such as the hydroxy benzoic acids and hydroxynaphthoic acids, and bis(2-hydroxyethyl) terephthalate.
• oligomer means a molecule that contains 2 or more identifiable structural repeat units of the same or different formula.
• linear polyester oligomer means oligomeric material, excluding macrocyclic polyester oligomers (vide infra), which by itself or in the presence of monomers can polymerize to a higher molecular weight polyester.
• Linear polyester oligomers include, for example, oligomers of linear polyesters and oligomers of polymerizable polyester monomers.
• reaction of dimethyl terephthalate or terephthalic acid with ethylene glycol when carried out to remove methyl ester or carboxylic groups, usually yields a mixture of bis(2-hydroxyethyl) terephthalate and a variety of oligomers: oligomers of bis(2-hydroxyethyl) terephthalate, oligomers of mono(2-hydroxyethyl) terephthalate (which contain carboxyl groups), and polyester oligomers capable of being further extended.
• such oligomers will have an average degree of polymerization (average number of monomer units) of about 20 or less, more preferably about 10 or less.
• a "macrocyclic" molecule means a cyclic molecule having at least one ring within its molecular structure that contains 8 or more atoms covalently connected to form the ring.
• macrocyclic polyester oligomer means a macrocyclic oligomer containing 2 or more identifiable ester functional repeat units of the same or different formula.
• a macrocyclic polyester oligomer typically refers to multiple molecules of one specific formula having varying ring sizes. However, a macrocyclic polyester oligomer may also include multiple molecules of different formulae having varying numbers of the same or different structural repeat units.
• a macrocyclic polyester oligomer may be a co-oligoester or multi-oligoester, i.e., a polyester oligomer having two or more different structural repeat units having an ester functionality within one cyclic molecule.
• the method comprises the steps: a. preparing a polyester nanocomposite by mixing a sepiolite- type clay with at least one polyester precursor selected from the group (i) at least one diacid or diester and at least one diol;
• the nanocomposite contains an effective amount of exfoliated sepiolite, exfoliated attapulgite, or a mixture of exfoliated sepiolite and exfoliated attapulgite.
• an effective amount means that enough barrier enhancing additive is present to cause a detectable decrease in the permeability of the article to the permeating substance of interest (e.g., oxygen). This is from 0.1% by wt. to 20% by wt. of the polyester nanocomposite.
• Clay minerals and their industrial applications are reviewed by H. H. Murray in Applied Clay Science 17(2000) 207-221.
• Two types of clay minerals are commonly used in nanocomposites: kaolin and smectite.
• the molecules of kaolin are arranged in two sheets or plates, one of silica and one of alumina.
• the most widely used smectites are sodium montmorillonite and calcium montmorillonite.
• Smectites are arranged in two silica sheets and one alumina sheet.
• the molecules of the montmorillonite clay minerals are less firmly linked together than those of the kaolin group and are thus further apart.
• Sepiolite is a hydrated magnesium silicate filler that exhibits a high aspect ratio due to its fibrous structure.
• sepiolite is composed of long lath-like crystallites in which the silica chains run parallel to the axis of the fiber.
• the material has been shown to consist of two forms, an ⁇ and a ⁇ form.
• the ⁇ form is known to be long bundles of fibers and the ⁇ form is present as amorphous aggregates.
• Attapulgite also known as palygorskite
• sepiolite-type clay includes attapulgite as well as sepiolite itself.
• Sepiolite-type clays are layered fibrous materials in which each layer is made up of two sheets of tetrahedral silica units bonded to a central sheet of octahedral units containing magnesium ions (see, e.g., Figures 1 and 2 in L. Bokobza et al., Polymer International, 53, 1060-1065 (2004)).
• the fibers stick together to form fiber bundles, which in turn can form agglomerates.
• These agglomerates can be broken apart by industrial processes such as micronization or chemical modification (see, e.g., European Patent 170,299 to Tolsa, SA).
• the amount of sepiolite-type clay used in the present invention ranges from about 0.1 to about 20 wt % based on the final composite composition. The specific amount chosen will depend ' on the intended use of the nanocomposite, as is well understood in the art.
• Sepiolite-type clays are available in a high purity (“rheological grade"), uncoated form (e.g., PANGEL® S9 sepiolite clay from the Tolsa Group, Madrid, Spain) or, more commonly, treated with an organic material to make the clay more "organophilic," i.e., more compatible with systems of low-to-medium polarity (e.g., PANGEL® B20 sepiolite clay from the Tolsa Group).
• An example of such a coating for sepiolite-type clay is a quaternary ammonium salt such as dimethylbenxylalkylammonium chloride, as disclosed in European Patent Application 221 ,225.
• smectic clay e.g., a montmorillonite
• barrier properties are greatly improved because the large surface area of the platelets greatly increases the tortuosity of the path a diffusing species must follow in permeating through the polymeric material.
• sepiolite-type clay is exfoliated into long, lath-like crystallites. It is thus a highly unexpected finding that exfoliated sepiolite- type clay is effective in increasing the barrier properties of a polymer matrix into which it is incorporated.
• the polyester used may be any polyester with the requisite melting point.
• the melting point of the polyester is about 15O 0 C or higher, and more preferably about 200 0 C or higher.
• Polyesters (which have mostly or all ester linking groups) are normally derived from one or more dicarboxylic acids and one or more diols. They can also be produced from polymerizable polyester monomers or from macrocyclic polyester oligomers.
• Polyesters most suitable for use in practicing the invention comprise isotropic thermoplastic polyester homopolymers and copolymers (both block and random).
• polyesters from diols and hydrocarbyl diacids or esters of such diacids is well known in the art, as described by A. J. East, M. Golden, and S. Makhija in the Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, J. I. Kroschwitz exec, ed., M. Howe- Grant, ed., 4 th edition (1996), vol. 19, 609-653.
• esterification or ester interchange between the diacid or its dialkyl (typically dimethyl) ester and the diol takes place to give the bis(hydroxyalkyl)ester and some oligomers along with the evolution and removal of water or alcohol (typically methanol).
• esterification or ester-interchange is an inherently slow reaction
• useful esterification or ester- interchange catalysts are calcium, zinc, and manganese acetates; tin compounds; and titanium alkoxides.
• the bis(hydroxyalkyl)ester and oligomers continue to undergo ester-interchange reactions, eliminating diol, which is removed under high vacuum, and building molecular weight.
• useful polycondensation catalysts include tin and titanium compounds, antimony, and germanium compounds, particularly antimony oxide (Sb 2 U 3 ) in the case of PET.
• suitable diacids are those selected from the group consisting of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acids, cyclohexane dicarboxylic acids, succinic acid, glutaric acid, adipic acid, sebacic acid, 1 ,12-dodecane dioic acid fumaric acid, maleic acid, and the derivatives thereof, such as, for example, the dimethyl, diethyl, or dipropyl esters.
• glycols that can be utilized as the diol component include ethylene glycol, 1 ,3-propylene glycol, 1 ,2- propylene glycol, 2,2-diethyl-1 ,3-propane diol, 2,2-dimethyl-1 ,3-propane diol, 2-ethyl-2-butyl-1 ,3-propane diol, 2-ethyl-2-isobutyl-1 ,3-propane diol, 1 ,3-butane diol, 1 ,4-butane diol, 1 ,5-pentane diol, 1 ,6-hexane diol, 2,2,4- trimethyl-1 ,6-hexane diol, 1 ,2-cyclohexane dimethanol.
• 1 ,3-cyclohexane dimethanol 1 ,4-cyclohexane dimethanol, 2,2,4,4-tetramethyl-1 ,3- cyclobutane diol, isosorbide, naphthalene glycols, diethylene glycol, triethylene glycol, resorcinol, hydroquinone, and longer chain diols and polyols, such as polytetramethylene ether glycol, which are the reaction products of diols or polyols with alkylene oxides.
• the dicarboxylic acids comprise one or more of terephthalic acid, isophthalic acid and 2,6-naphthalene dicarboxylic acid
• the diol component comprises one or more of HO(CH 2 ) n OH (I), 1 ,4-cyclohexanedimethanol, HO(CH 2 CH 2 ⁇ ) m CH 2 CH 2 ⁇ H (II), and HO(CH 2 CH 2 CH 2 CH 2 O) 2 CH 2 CH 2 CH 2 CH 2 OH (III), wherein n is an integer of 2 to 10, m on average is 1 to 4, and z on average is about 7 to about 40.
• (II) and (III) may be a mixture of compounds in which m and z, respectively, may vary and hence since m and z are averages, they do not have to be integers.
• n 2, 3 or 4, and/or m is 1.
• Polyesters can also be produced directly from polymerizable polyester monomers.
• suitable polymerizable polyester monomers for use in the present invention include hydroxyacids such as hydroxybenzoic acids, hydroxynaphthoic acids and lactic acid; bis(2-hydroxyethyl) terephthalate, bis(4-hydroxybutyl) terephthalate, bis(2-hydroxyethyl)naphthalenedioate, bis(2- hydroxyethyl)isophthalate, bis[2-(2-hydroxyethoxy)ethyl]terephthalate, bis[2-(2-hydroxyethoxy)ethyI]isophthalate, bis[(4- hydroxymethylcyclohexyl)methyl]terephthalate, and bis[(4- hydroxymethylcyclohexyl)methyl]isophthalate, mono(2- hydroxyethyl)terephthalate, bis(2-hydroxyethyl)sulfoisophthalate, and lactide.
• Polyesters can also be produced directly from macrocyclic polyester oligomers.
• Macrocyclic polyester oligomers that may be employed in this invention include, but are not limited to, macrocyclic poly(alkylene dicarboxylate) oligomers having a structural repeat unit of the formula:
• A is an alkylene group containing at least two carbon atoms, a cycloalkylene, or a mono- or polyoxyalkylene group
• B is a divalent aromatic or alicyclic group.
• A is an alkylene group containing at least two carbon atoms, a cycloalkylene, or a mono- or polyoxyalkylene group
• B is a divalent aromatic or alicyclic group.
• They may be prepared in a variety of ways, such as those described in U.S. Pat. Nos. 5,039,783, 5,231 ,161 , 5,407,984, 5,668,186, United States Provisional Patent Application No. 60/626187, PCT Patent Applications WO 2003093491 and WO 2002068496, and A. Lavalette, et al., Biomacromolecules, vol. 3, p. 225- 228 (2002). Macrocyclic polyester oligomers can also be obtained through extraction from low-molecular weight linear polyester.
• Preferred macrocyclic polyester oligomers are macrocyclic polyester oligomers of 1 ,4-butylene terephthalate (CBT); 1 ,3-propylene terephthalate (CPT); 1 ,4-cyclohexylenedimethylene terephthalate (CCT); ethylene terephthalate (CET); 1 ,2-ethylene 2,6-naphthalenedicarboxylate (CEN); the cyclic ester dimer of terephthalic acid and diethylene glycol (CPEOT); and macrocyclic co-oligoesters comprising two or more of the above structural repeat units.
• CBT 1 ,4-butylene terephthalate
• CPT 1 ,3-propylene terephthalate
• CCT ethylene terephthalate
• CEN ethylene 2,6-naphthalenedicarboxylate
• CPEOT the cyclic ester dimer of terephthalic acid and diethylene glycol
• the polyesters may be branched or unbranched, and may be homopolymers or copolymers or polymeric blends comprising at least one such homopolymer or copolymer.
• polyesters include poly(ethylene terephthalate) (PET), poly(1 ,3-propylene terephthalate) (PPT), poly(1 ,4-butylene terephthalate) (PBT), a thermoplastic elastomeric polyester having poly(1 ,4-butylene terephthalate) and poly(tetramethylene ether)glycol blocks (available as HYTREL® from E. I. du Pont de Nemours & Co., Inc., Wilmington, DE 19898 USA), poly(1 ,4-cylohexyldimethylene terephthalate) (PCT), and polylactic acid (PLA). PET is especially preferred.
• PET is especially preferred.
• polyesters which are defined as being modified with up to 10% by weight of a comonomer.
• polyester polymer or oligomer
• unmodified polyester polymers or oligomers.
• PET poly(ethylene terephthalate)
• Comonomers can include diethylene glycol (DEG), triethylene glycol, 1 ,4-cyclohexane dimethanol, isosorbide, isophthalic acid (IPA), 2,6-naphthalene dicarboxylic acid, adipic acid and mixtures thereof.
• DEG diethylene glycol
• IPA isophthalic acid
• 2,6-naphthalene dicarboxylic acid 2,6-naphthalene dicarboxylic acid
• adipic acid and mixtures thereof.
• the polyester base polymer is polyethylene terephthalate (PET), which includes PET polymer which has been modified with from about 2 mole % up to about 5 mole % of isophthalate units.
• PET polyethylene terephthalate
• Such modified PET is known as "bottle grade” resin and is available commercially as MELI NAR® LASER+® polyethylene terephthalate brand resin from ADVANSA, a wholly owned company of Haci Omer Sabanci AS of Turkey.
• Process conditions for making the nanocomposite material are the same as those known in the art for manufacturing polyesters in a melt or solution process.
• the sepiolite clay mineral can be added by any means known in the art at any convenient stage of manufacture before the polyester degree of polymerization is about 20. For example, it can be added at the beginning with the monomers, during monomer esterification or ester-interchange, at the end of monomer esterification or ester- interchange, or early in the polycondensation step.
• a range of catalysts can be used. These include the use of lithium acetate buffers as described in U.S. Patent 3,749,697 and a range of sodium and potassium acetate buffers as described in JP 83- 62626, RO 88-135207, and JP 2001-105902. Typically, 100-600 ppm of sodium or potassium acetate was used during the polymerization to minimize the degree of DEG formation and incorporation into the polymer. Formation of Articles
• Film samples are indicative of the improved gas barrier properties obtainable from the invention.
• the nanocomposite is prepared by in situ polymerization of the base polymer in the presence of a sepiolite-type clay, as described above.
• the nanocomposite can then be used to make film, sheet, or containers by any method known to one of ordinary skill in the art.
• Film, sheet, and containers comprising the nanocomposite exhibit increased tear strength; increased tensile modulus; decreased permeability to water vapor, oxygen, and carbon dioxide; and retain a high level of toughness and clarity.
• the polyester nanocomposite can be used alone or as a component of a polymer blend. Additives commonly used in the art can be incorporated, such as, but not limited to, antioxidants, antistatic agents, heat stabilizers, UV stabilizers, slip agents, and antiblock agents.
• Articles of the present invention may be in the form of or comprise, but are not limited to, film, sheet, container, membrane, laminate, pellet, coating, or foam.
• Articles may be prepared by any means known in the art, such as, but not limited to, methods of injection molding, (co)extrusion, blow molding, thermoforming, solution casting, lamination, and film blowing.
• the article is an injection stretch blow molded bottle.
• the preferred articles of the present invention include packaging for food, personal care (health and hygiene) items, and cosmetics.
• packaging is meant either an entire package or a component of a package.
• packaging components include, but are not limited, to packaging film, liners, shrink bags, shrink wrap, trays, tray/container assemblies, replaceable and nonreplaceable caps, lids, and drink bottle necks.
• the package may be in any form appropriate for the particular application, such as a can, box, bottle, jar, bag, cosmetics package, or closed-ended tube.
• the packaging may be fashioned by any means known in the art, such as, but not limited to, extrusion, coextrusion, thermoforming, injection molding, lamination, or blow molding.
• packaging for personal care items and cosmetics include, but are not limited to, bottles, jars, and caps for food and for prescription and non-prescription capsules and pills; solutions, creams, lotions, powders, shampoos, conditioners, deodorants, antiperspirants, and suspensions for eye, ear, nose, throat, vaginal, urinary tract, rectal, skin, and hair contact; and lip product.
• Dimethyl terephthalate (CAS # 120-61-6, 99%) was purchased from INVISTA (Wichita, Kansas). Ethylene glycol (CAS #107-21-1) was purchased from Univar USA (Kirkland, Washington). Antimony oxide (CAS 1309-64-4, 99%), and manganese acetate (CAS # 6156-78-1 , 99%) were purchased from Aldrich Chemical Company (Milwaukee, Wisconsin). PANGEL® B20 sepiolite was purchased from EM Sullivan Associates. The control PET sample used was CRYSTAR® 3934 (E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware). The two EASTAR® PETG grades were purchased from the Eastman Chemical Company (Kingsport, Tennessee).
• a size exclusion chromatography system comprised of a Model Alliance 2690TM from Waters Corporation (Milford, MA), with a Waters 410TM refractive index detector (DRI) and Viscotek Corporation (Houston, TX) Model T-60ATM dual detector module incorporating static right angle light scattering and differential capillary viscometer detectors was used for molecular weight characterization.
• the mobile phase was 1 ,1 ,1 ,3,3,3- hexafluoro-2-propanol (HFIP) with 0.01 M sodium trifluoroacetate.
• HFIP hexafluoro-2-propanol
• the percentage of diethylene glycol (DEG) was determined using 1 H NMR spectroscopy.
• the tensile properties of the nanocomposite film were determined according to ASTM procedure D882.
• the water vapor transmission rate was performed using a MOCON® PERMATRAN-W® (MOCON®, Inc., Minneapolis, Minnesota) at 25 0 C 1 100% relative humidity, according to ASTM procedure D6701. Yellowness was evaluated by eye or measured according to ASTM D1003 at 50% relative humidity, as indicated.
• a stainless steel autoclave was charged with DMT (10.1 lbs, 4.59 kg), ethylene glycol (6.7 lbs, 3.0 kg), antimony trioxide (2.80 g), manganese acetate (3.60 g), sodium acetate (1.30 g), and PANGEL® B20 sepiolite (140.0 g).
• the reaction vessel was purged with 60 psi of nitrogen three times.
• the vessel was heated to 24O 0 C with a low flow nitrogen sweep of the vessel. While the vessel was heating to 240 0 C, the reaction was agitated at 25 RPM. After the vessel reached 24O 0 C, the reaction temperature was maintained for 10 min. The reaction was then heated to 275°C and a 90 minute vacuum reduction cycle was begun.
• a CRYSTAR® polyester polymer (unfilled) as a control and the polyester/sepiolite nanocomposite (3 wt% sepiolite) prepared in Example 1 were dried overnight at 120 0 C under vacuum.
• a 30 mm twin screw extruder was fitted with a 10" (25.4 cm) film die and feeder with a nitrogen blanket. The barrel was heated to a temperature of 255 0 C and the die was heated to 265°C. The film was extruded and cooled on a cooled casting drum. A filter screen was not used during extrusion. Clarity and color were evaluated by eye. Tensile modulus and VWTR were measured as described above. Results are presented in Table 1.
• the feeds for Samples 3A, 3B, 3C, and 3D were the PET nanocomposite composition from Example 1 ("PET-Example 1"); a 1 :1 by weight pellet blend of PET-Example 1 and EASTAR® 21446; a 1 :1 by weight pellet blend of PET-Example 1 and EASTAR® 6763; and the CRYSTAR® 3934 control.
• Sheet of 35 mil (889 ⁇ m) thickness was extruded and cooled on a cooled casting drum. A filter screen was not used during extrusion. Yellowness was measured according to ASTM D1003 and is presented in Table 2. Tensile properties are presented in Table 3. Table 2

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