Patent Publication Number: US-2016222156-A1

Title: Ndca-based polyesters made with isosorbide

Description:
FIELD OF THE INVENTION 
     This invention relates to polyester polymers comprising the reaction products of (a) one or more diacid, diester thereof, or glycolide, and (b) one or more polyol, wherein component (a) consists essentially of 2,6-napthalene dicarboxylic acid (NDCA), C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. The invention further relates to compositions which comprise blends of such polymer, and articles, such as single- and multi-layer films, made with such polymers. 
     BACKGROUND 
     Polyethylene terephthalate (PET) is widely used in both flexible and rigid packaging. There is a need to provide polymer films with improved barrier properties to oxygen, carbon dioxide and moisture to accommodate increasing demands in lighter weighting of bottles, simpler designs, and longer shelf life of packaged food, including produce, meat, fish, and cheese and other dairy products. In addition, with the emphasis on technologies based on sustainable chemistry, there has been increased interest in films based on monomers from renewable sources, such as polyethylene furanoate based on furan dicarboxylic acid, which can be produced using bioderived compounds, such as fructose. 
     Several new polymers with high barrier properties have been developed from either renewable or non-renewable resources and some of these have already been commercialized. These include polyethylene naphthalate (PEN), polyglycolic acid (PGA), and polyethylene furanoate (PEF). For those polymers, the oxygen barrier property (at about 23° C. and 50% relative humidity) follows the order:
         PGA≈EVOH&gt;PEN≈PEF&gt;PET
 
Compared to PET, PEF has been reported to have six times improved oxygen barrier, two times improved barrier to carbon dioxide, and also improved moisture barrier. “Bioplastics, Reshaping the Industry”, Las Vegas, Feb. 3, 2011.
       

     In WO 2010/0177133 (Sipos, assigned to Furanix Technologies B.V.), a process for the production of PEF polymers and copolymers made from 2,5-furandicarboxylate is disclosed. The (co)polymers have a number average molecular weight of at least 10,000 (as determined by GPC based on polystyrene standards), and an absorbance below 0.05 (as a 5 mg/ml solution in a dichlomethane:hexafluoroisopropanol 8:2 mixture at 400 nm). These (co)polymers may be subjected to solid state polycondensation and then attain a number average molecular weight greater than 20,000 (as determined by GPC based on polystyrene standards), without suffering from discoloration. 
     There remains a need for novel polymers which can be used to form films in a cost-effective manner that exhibit a desirable balance of properties, such as improved oxygen, carbon dioxide, and water-vapor permeability, higher glass transition temperature (Tg), and improved toughness, chemical, heat and impact resistance. There is, further, a need for novel polymers which can used to form films with high-temperature heat sealability using alternative sealing technologies. 
     The present invention achieves these objectives by forming a film from a component (a) consists essentially of 2,6-napthalene dicarboxylic acid, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide, by esterification or transesterification, respectively, in presence of suitable catalysts, followed by further polycondensation at higher temperature and optionally at reduced pressure, and using solid state polymerization to increase the molecular weight. 
     SUMMARY OF THE INVENTION 
     The present invention relates to polymers comprising reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of 2,6-napthalene dicarboxylic acid (NDCA), C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. One suitable diester is dimethyl naphthanoate (DMN). 
     Component (a) (diacid or diester) consists essentially of NDCA or C 1  to C 10  alkyl diester thereof, or combinations thereof. The component (a) may comprise small amounts of other diacids or diesters, such as 2,5-furan dicarboxylic acid (FDCA), C 1  to C 10  alkyl diester thereof (e.g., dimethyl furanoate (DMF)), glycolide, or combinations thereof. Component (a) may comprise 5 mole % or less, or 1 mole % or less, or 0.5 mole % or less of FDCA, C 1  to C 10  alkyl diester thereof, glycolide, or combinations thereof. Preferably, component (a) consists essentially of (i.e., at least 95, or 99, or 99.5 mole %), or consists entirely of, NDCA or C 1  to C 10  alkyl diester thereof, or combinations thereof. Preferably, component (a) is NDCA or DMN. 
     The polymer may be formed from component (a) comprising 1 to 99 mole % NDCA, and 1 to 99 mole % C 1  to C 10  alkyl diester of NDCA or combinations thereof, based on the total amount of component (a). Preferably, component (a) consists essentially of NDCA, or consist essentially of C 1  to C 10  alkyl diester of NDCA or combinations of such diesters. That is, component (a) is preferably entirely or essentially all either diacid or diester, not a substantial combination of both diacid and diester(s). 
     The polyol component (b) comprises isosorbide. Component (b) may consist essentially of isosorbide, or may consist (consist entirely) of isosorbide. When component (b) contains other polyols besides just isosorbide, component (b) may comprise ethylene glycol, a mixture of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or combinations thereof. For example, component (b) may comprise 10 to 90 mole %, based on the total amount of component (b) polyol, of isosorbide, and 10 to 90 mole % based on the total amount of component (b) polyol, of ethylene glycol, a mixture of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or combinations thereof. 
     When component (b) contains a mixture of 1,3- and 1,4-cyclohexanedimethanol, the cyclohexanedimethanol may comprise 25 to 75 mole % of 1,3-cyclohexanedimethanol and 25 to 75 mole % of 1,4-cyclohexanedimethanol. As an example, the cyclohexanedimethanol may comprise 45 to 65 mole % of 1,3-cyclohexanedimethanol and 35 to 55 mole % of 1,4-cyclohexanedimethanol. As a further example, the cyclohexanedimethanol may comprise 55 mole % of 1,3-cyclohexanedimethanol and 45 mole % of 1,4-cyclohexanedimethanol. 
     The invention further includes compositions comprising (1) one or more first polymer comprising reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide, and (2) one or more second polymer selected from the group consisting (A) of polymers of (1) above different from the first polymer and (B) other polyesters which are reaction product of (i) acids or esters and (ii) polyols, wherein (x) the acids and esters do not include NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, when the polyol comprises isosorbide, and (y) wherein the polyols do not include isosorbide when the acids and esters comprise NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof. This composition may comprise two or more polymers, wherein at least one polymer is the reaction product of NDCA, and at least one other polymer is the reaction product of C 1  to C 10  alkyl diester of NDCA or combinations thereof. 
     The composition may comprise one or more other polyester comprising a reaction product of component (i) FDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, glycolide, and component (ii) one or more polyol comprising isosorbide, ethylene glycol, mixture of 1,3- and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or combinations thereof. 
     The other polyester may also comprise aliphatic homopolymer polyglycolide or polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), copolymer polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), polyethylene terephthalate (PET), semi-aromatic copolymer PET, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and aromatic copolymers from polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid. 
     The invention further includes an article comprising one or more polymers or compositions described above. Examples of such articles include, but are not limited to, thermoformed articles, film, shrink label, retortable packaging, pipe, bottle, profile, molded article, extruded article, fiber, and fabric. Rigid or semi-rigid (i.e., somewhat deformable) bottles and various rigid articles may be made using conventional blow-molding processes well-known in the art. 
     The invention further includes methods of forming films or sheets comprising the steps of (i) extruding a polymer to form an extrudate; (ii) shaping the extrudate by passing it through a flat or annular die; and (iii) cooling the extrudate to form a film or sheet having a machine direction and a cross direction; wherein the polymer comprises reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. The method may comprise the further step of orienting the film or sheet in the machine or cross direction, or both. 
     The invention further includes a film or sheet of one or more layers, wherein at least one layer comprises polymer comprising the reaction product of (a) one or more diacid, diester thereof, or glycolide, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. 
     The invention further comprises a barrier film comprising a polyester-based polymer with (a) an O 2  gas permeability of 0.4 cc-mil/100 in 2  24 hrs atm (8 cc 20 μ/m 2  24 hrs atm) at 50% relative humidity (ASTM D-3985) or less, (b) a moisture permeability of less than 0.5 g mil/100 in. 2  24 hrs atm (9.8 g 20 μ/m 2  24 hrs atm) at 38° C. (ASTM F-1249) or less, and (c) a glass transition temperature of 100° C. or higher. The barrier film may further have (x) a Falling dart drop impact (Type A) of 200 g or greater (ASTM D-1709) for a 50 micron thick film material at room temperature and 50% relative humidity, (y) an Elmendorf tear of 400 g or greater (ASTM D-1922 for a 50 micron thick film material) at room temperature and 50% relative humidity, and (z) a notched Izod impact of 1.0 J/cm or greater at room temperature and 50% relative humidity (ASTM D-256 for rigid materials). Preferably, the film has properties (a), (b) and (c), and one or more of properties (x), (y) and (z). 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides cost-effective polymers that exhibit a desirable balance of properties, relative to PEF polymers, including improved oxygen, carbon dioxide, and water-vapor permeability, higher glass transition temperature (Tg), and improved chemical, heat and impact resistance. In addition, these polymers can be used to form films with high-temperature heat sealability using alternative sealing technologies. 
     The polymers of the present invention comprise the reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. One suitable diester of NDCA is dimethyl naphthanoate (DMN). 
     Component (a) (diacid or diester) consists essentially of NDCA or C 1  to C 10  alkyl diester thereof, or combinations thereof. The component (a) may comprise small amounts of other diacids or diesters, such as, for example, 2,5-furan dicarboxylic acid (FDCA), C 1  to C 10  alkyl diester thereof (e.g., dimethyl furanoate (DMF)), glycolide, or combinations thereof. Component (a) may comprise 5 mole % or less, or 1 mole % or less, or 0.5 mole % or less of FDCA, C 1  to C 10  alkyl diester thereof, glycolide, or combinations thereof. Preferably, component (a) consists essentially of (i.e., at least 95, or 99, or 99.5 mole %), or consists entirely of, NDCA or C 1  to C 10  alkyl diester thereof, or combinations thereof. Preferably, component (a) is NDCA or DMN. Glycolic acid could be used in place of, or in addition to, glycolide as described herein, but its use is not favored for practical reasons. 
     The polymer may be formed from component (a) comprising 1 to 99 mole % NDCA, and 1 to 99 mole % C 1  to C 10  alkyl diester of NDCA or combinations thereof based on the total amount of component (a). Preferably, component (a) consists essentially of NDCA, or consist essentially of C 1  to C 10  alkyl diester of NDCA or combinations of such diesters. That is, component (a) is preferably entirely or essentially all either diacid or diester, not a substantial combination of both diacid and diester(s). 
     The terms “NDCA-based polymer” refer to polymers made from either the diacid or the diesters, and refer to polymers made from NDCA itself or DMN or other diesters of NDCA and other minimal amounts of other diacids or diesters as described herein (not just NDCA or DMN); i.e., FDCA, C 1  to C 10  alkyl diester of FDCA, glycolide or combinations thereof. As described herein, such NDCA-based polymers may comprise residues of other diacids and diesters as well. 
     The polyol component (b) comprises isosorbide. Component (b) may consist essentially of isosorbide, or may consist (consist entirely) of isosorbide. When component (b) contains other polyols beside just isosorbide, component (b) may comprise ethylene glycol, a mixture of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or combinations thereof. The polyol component (b) may comprise 1 mole % or more, 5 mole % or more, 10 mole % or more, 30 mole % or more, 50 mole % or more, 70 mole % or more, 80 mole % or more, 90 mole % or more, 95 mole % or more, 99 mole % or more, or 100 mole % isosorbide, based on the total amount of component (b). The polyol component (b) may comprise 100 mole % or less, 95 mole % or less, 90 mole % or less, 80 mole % or less, 70 mole % or less, 50 mole % or less, 30 mole % or less, 10 mole % or less, 5 mole % or less, 1 mole % or less isosorbide, based on the total amount of component (b). For example, component (b) may comprise 10 to 90 mole %, based on the total amount of component (b) polyol, of isosorbide, and 10 to 90 mole % based on the total amount of component (b) polyol, of ethylene glycol, a mixture of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or other polyols, or combinations thereof. 
     When component (b) contains a mixture of 1,3- and 1,4-cyclohexanedimethanol, the cyclohexanedimethanol may comprise 25 to 75 mole % of 1,3-cyclohexanedimethanol and 25 to 75 mole % of 1,4-cyclohexanedimethanol. As an example, the cyclohexanedimethanol may comprise 45 to 65 mole % of 1,3-cyclohexanedimethanol and 35 to 55 mole % of 1,4-cyclohexanedimethanol. As a further example, the cyclohexanedimethanol may comprise 55 mole % of 1,3-cyclohexanedimethanol and 45 mole % of 1,4-cyclohexanedimethanol. 
     The invention further includes compositions comprising (1) one or more first polymer comprising reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide, and (2) one or more second polymer selected from the group consisting (A) of polymers of (1) above different from the first polymer and (B) other polyesters which are reaction product of (i) acids or esters and (ii) polyols, wherein (x) the acids and esters do not include NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, when the polyol comprises isosorbide, and (y) wherein the polyols do not include isosorbide when the acids and esters comprise NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof. This composition may comprise two or more polymers, wherein at least one polymer is the reaction product of NDCA, and at least one other polymer is the reaction product of C 1  to C 10  alkyl diester of NDCA or combinations thereof. 
     The composition may comprise one or more other polyester comprising a reaction product of component (i) FDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, or glycolide, and component (ii) one or more polyol comprising isosorbide, ethylene glycol, mixture of 1,3- and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or combinations thereof. 
     The polymers of the present invention have a glass transition temperature (Tg) of at least 100° C. as measured by differential scanning calorimetry (DSC) or calculated according to the Fox Equation (see, T. G. Fox, Bull. Am. Physics Soc., vol. 1(3), p. 123 (1956)). Preferably, the Tg of the polymers is in the range from 100 to 150° C., or 110 to 150° C., or 120 to 150° C. Polymers with Tg of 100° C. or higher, and preferably 120° C. or higher, and the films, sheets and articles made from them, exhibit desirable physical characteristics as described elsewhere herein. 
     The polymers and copolymers described above may be prepared by known methods. WO 2010/0177133, referenced above, teaches methods to make these polyesters, and produce them at high molecular weights and without discoloration. The method of WO 2010/0177133 is applicable to preparing the present polymers using NDCA or DMN or other C 2  to C 10  alkyl diesters of NDCA. 
     For example, the polymers of the present invention may be made by a two-step process, wherein first, in Step (I), a prepolymer is made having 2,6-napthalene dicarboxylate moieties within the polymer backbone. This intermediate product is preferably an ester composed of two diol monomers and one diacid monomer, wherein the diacid monomers comprise NDCA, followed by a melt-polymerization of the prepolymers under suitable polymerization conditions. Such conditions typically involve reduced pressure to remove the excess of diol monomers. Using DMN as examples of the diester, in Step (I) DMN is reacted in a catalyzed transesterification process with about 2 equivalents of a diol, to generate the prepolymer while removing 2 equivalents of the corresponding alcohol. DMN is preferred, since this transesterification step then generates methanol, a volatile alcohol that is easy to remove. However, as starting material diesters of NDCA with other volatile alcohols or phenols (e.g., having a boiling point at atmospheric pressure of less than 150° C., preferably less than 100° C., more preferably of less than 80° C.) may be used as well. Examples, therefore, include ethanol, methanol and a mixture of ethanol and methanol. The reaction leads to formation of a polyester. As discussed in more detail below, the diol monomers may contain additional hydroxyl groups, such as glycerol, pentaerythritol or sugar alcohols. 
     Step (I) is commonly referred to as esterification when acid is used, and transesterification when ester is used, with concomitant removal of water or an alcohol, respectively. Step (II) of the process is a catalyzed polycondensation step, wherein the prepolymer is polycondensed under reduced pressure, at an elevated temperature and in the presence of a suitable catalyst. 
     The first step, transesterification, is catalyzed by a specific transesterification catalyst at a temperature preferably in the range of about 150 to about 220° C., more preferably in the range of about 180 to about 200° C., and carried out until the starting ester content is reduced until it reaches the range of about 3 mole % to about 1 mole %. The transesterification catalyst may be removed, to avoid interaction in the second step of polycondensation, but often remains present for the second step. The selection of the transesterification catalyst can be affected by the selection of the catalyst used in the polycondensation step, and vice versa. 
     Suitable catalysts for use in the Step (I) transesterification process include tin(IV) based catalysts, preferably organotin(IV) based catalysts, more preferably alkyltin(IV) salts including monoalkyltin(IV) salts, dialkyl and trialkyltin(IV) salts and mixtures thereof. The tin(IV) based catalysts are better than tin(II) based catalysts, such as tin(II) octoate. 
     The tin(IV) based catalysts may also be used with alternative or additional transesterification catalysts. Examples of alternative or additional transesterification catalysts that may be used in Step (I) include one or more of titanium(IV) alkoxides or titanium(IV) chelates, zirconium(IV) chelates, or zirconium(IV) salts (e.g. alkoxides); hafnium(IV) chelates or hafnium(IV) salts (e.g. alkoxides). Although these alternative or additional catalysts may be suitable for the transesterification, they may actually interfere during the polycondensation step. Therefore, preferably, the main or sole transesterification catalyst is a tin(IV) based catalyst. Alternatively, when alternative or additional catalysts are used, they are removed after Step (I) and before Step (II). 
     Preferred transesterification catalysts are selected from one or more of, butyltin(IV) tris(octoate), dibutyltin(IV) di(octoate), dibutyltin(IV) diacetate, dibutyltin(IV) laureate, bis(dibutylchlorotin(IV)) oxide, dibutyltin dichloride, tributyltin(IV) benzoate and dibutyltin oxide. 
     In respect to the catalyst, it should be realized that the active catalyst as present during the reaction may be different from the catalyst as added to the reaction mixture. The catalysts are used in an amount of about 0.01 to about 0.2 mole % relative to initial diester, more preferably in an amount of about 0.04 to about 0.16 mole % of initial diester. 
     The intermediate product (i.e., the prepolymer) may, but importantly need not be isolated and/or purified. Preferably, the product is used as such in the subsequent polycondensation step. In this catalyzed polycondensation step, the prepolymer is polycondensed under reduced pressure, at an elevated temperature and in the presence of a suitable catalyst. The temperature is preferably in the range of about the melting point of the polymer to about 30° C. above this melting point, but preferably not less than about 180° C. The pressure should be reduced, preferably gradually at stages. It should preferably be reduced to as low as a pressure as possible, more preferably below 1 mbar. Step (II) is catalyzed by specific polycondensation catalysts and the reaction is carried out at mild melt conditions. 
     Examples of suitable polycondensation catalysts for use in Step (II) include tin(II) salts, such as tin(II) oxide, tin(II) dioctoate, butyltin(II) octoate, or tin(II) oxalate. Preferred catalysts are tin(II) salts obtained by the reduction of the tin(IV) catalyst, e.g., alkyltin(IV), dialkyltin(IV), or trialkyltin(IV) salts, used as transesterification catalyst in Step (I), with a reducing compound. Reducing compounds used may be well-known reducing compounds, preferably phosphorus compounds. 
     Particularly preferred reducing compounds are organophosphorus compounds of trivalent phosphorus, in particular a monoalkyl or dialkyl phosphinate, a phosphonite or a phosphite. Examples of suitable phosphorus compounds are triphenyl phosphite, diphenyl alkyl phosphite, phenyl dialkyl phosphite, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, di(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, tristearylsorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl) 4,4′-diphenylenediphosphonite, 4,4′-isopropylidenediphenol C 12-15  alkyl phosphite, poly(dipropylene glycol) phenyl phosphite, tetraphenyl dipropylene glycol phosphite, tetraphenyl diisopropylene glycol phosphite, trisisodecyl phosphite, diisodecyi-phenyl phosphite, diphenyl isodecyl phosphite, and mixtures thereof. 
     The preferred polycondensation catalysts therefore include tin(II) salts such as tin(II) dioctoate, butyl(II) octoate and other alkyltin(II) octoate compounds, prepared from the corresponding tin(IV) salt using e.g., a trialkyl phosphite, a monoalkyl diaryl phosphite, a dialkyl monoaryl phosphite or a triaryl phosphite. Preferably, the reducing compound is added in the melt of the prepolymer. Addition of the reducing compound at that stage avoids discoloration. 
     A combination of transesterification catalyst and polycondensation catalyst that may be particularly suitable, is based on a tin(IV) type catalyst during transesterification, which is reduced, preferably with triphenylphosphite and/or tris(nonylphenyl)phosphite, to a tin(II) type catalyst during the polycondensation. The catalysts are used in an amount of about 0.01 to about 0.2 mole % relative to initial diester, more preferably in an amount of about 0.04 to about 0.16 mole % of initial diester. 
     It is particularly useful that the combination of tin(IV) type catalyst and tin(II) type catalyst retains activity. This allows for the same catalyst to be used for a subsequent solid state polycondensation. Solid state polycondensation (SSP) is a common process used in the preparation of other polyesters, such as PET. In SSP processes, pellets, granules, chips or flakes of polymer are subjected for a certain amount of time to elevated temperatures (below melting point) in a hopper, a tumbling drier or a vertical tube reactor or the like. With tin(IV)/tin(II) catalyst systems, higher molecular weight can be reached than with titanium catalysts. Tin type catalysts allow SSP of the NDCA-based polymers to reach a number average molecular weight of 20,000 and greater. Conditions and equipment for SSP are known, in particular as SSP is frequently used to upgrade recycled PET. In applying the SSP process to these polymer systems, the temperature should be elevated relative to traditional SSP processes (as for PET), but nonetheless remain below, and preferably well below, the melting point of the polymer. 
     Polyesters and various copolymers may be made according to the process described above, depending on the selection of the monomers used. Furthermore, the copolymers may be formed as random or block copolymers depending on the process and process conditions employed. For instance, linear polyesters may be made with NDCA (in the form of its methyl ester) and isosorbide and an aromatic, aliphatic or cycloaliphatic diol. The C 1  to C 10  alkyl diester of NDCA may be used in combination with one or more other dicarboxylic acid esters or lactones. Likewise, the diol may be a combination of two or more diols. 
     Polyesters that have never been produced before and that are claimed in this application are those having both a 2,6-napthalene dicarboxylate moiety and isosorbide within the polymer backbone. The polyesters will comprise residues of other diacid(s) and/or diester(s), and may comprise residues of other polyols as well. 
     The polymers and copolymers according to the current invention need not be linear. If a polyfunctional aromatic, aliphatic or cycloaliphatic alcohol is used, or part of the diol is replaced by such a polyol, then a branched or even crosslinked polymer may be obtained. A branched or crosslinked polymer may also be obtained when part of the NDCA ester is replaced by an ester of a polyacid. However, branching would reduce barrier properties, and too much crosslinking would impair film processability. As a result, the polymers should have only a moderate degree of branching or crosslinking, or little to essentially no branching or crosslinking, and preferably have no branching or crosslinking. 
     The diacids and diesters used in the present invention comprise NDCA and its C 1  to C 10  alkyl diesters. Component (a) (diacid or diester) consists essentially of NDCA or C 1  to C 10  alkyl diester thereof, or combinations thereof. The component (a) may comprise small amounts of other diacids or diesters, such as FDCA, C 1  to C 10  alkyl diester thereof (e.g., DMF), glycolide, or combinations thereof. Component (a) may comprise 5 mole % or less, or 1 mole % or less, or 0.5 mole % or less of FDCA, C 1  to C 10  alkyl diester thereof, glycolide, or combinations thereof. Preferably, component (a) consists essentially of (i.e., at least 95, or 99, or 99.5 mole %), or consists entirely of, NDCA or C 1  to C 10  alkyl diester thereof, or combinations thereof. Preferably, component (a) is NDCA or DMN. 
     The polymer may be formed from component (a) diacid or diester comprising 1 to 99 mole % NDCA, and 1 to 99 mole % C 1  to C 10  alkyl diester of NDCA or combinations thereof, based on the total amount of component (a). Preferably, component (a) consists essentially of NDCA, or consist essentially of C 1  to C 10  alkyl diester of NDCA or combinations of such diesters. That is, component (a) is preferably entirely or essentially all either diacid or diester, not a substantial combination of both diacid and diester(s). 
     Other diacids, diesters, lactones or lactides may be present as well. Suitable di- or polycarboxylic acid esters which can be used in combination with the DMN include DMF, dimethyl terephthalate, dimethyl isophthalate, dimethyl adipate, dimethyl azelate, dimethyl sebacate, dimethyl dodecanoate, dimethyl 1,4-cyclohexane dicarboxylate, dimethyl maleate, dimethyl succinate, and trimethyl 1,3,5-benzenetricarboxylate. Of these, preferred are DMF, dimethyl terephthalate, dimethyl adipate, dimethyl maleate, and dimethyl succinate As noted above, the amount of such other diacids, diesters, lactones or lactides is preferably less than 5 mole %, based on the total amount of diacids and diesters (and lactones and lactides) in the polymer. When a mixture is used, this mixture of reactants may be referred to as the acid ester reactant. 
     Examples of lactones include pivalolactone, ε-caprolactone and lactides (L,L; D,D; D,L) and glycolide. 
     The polymers and copolymers according to the current invention need not be linear. If a polyfunctional aromatic, aliphatic or cycloaliphatic alcohol is used, or part of the dihydroxyl polyol is replaced by a tri- or higher OH-functional polyol, then a branched or even crosslinked polymer may be obtained. A branched or crosslinked polymer may also be obtained when part of the DMN is replaced by an ester of a polyacid. Nevertheless, linear polymer and copolymer are preferred. 
     The polymers of the present invention are made using isosorbide, and the polyol may consist entirely of isosorbide, or may consist essentially of isosorbide. The polyol may comprise isosorbide and other polyol(s). Suitable other polyols may be selected from the group consisting of ethylene glycol, mixtures of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-benzenedimethanol, 2,2-dimethyl-1,3-propanediol, poly(ethylene glycol), poly(tetrahydofuran), 2,5-di(hydroxymethyl) tetrahydrofuran, glycerol, pentaerythritol, sorbitol, mannitol, erythritol, and threitol. Among those additional polyols which may be used to form the polymers of the present invention, preferred are ethylene glycol, mixture of 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, poly(ethylene glycol), and poly(tetrahydofuran), or combinations thereof. 
     When the polyol comprises mixtures of 1,3- and 1,4-cyclohexanedimethanol, this polyol component preferably comprises 25 to 75 mole % of 1,3-cyclohexanedimethanol and 25 to 75 mole % of 1,4-cyclohexanedimethanol, based on the total amount of polyol; more preferably, 45 to 65 mole % of 1,3-cyclohexanedimethanol and 35 to 55 mole % of 1,4-cyclohexanedimethanol, based on the total amount of polyol; and still more preferably, 55 mole % of 1,3-cyclohexanedimethanol and 45 mole % of 1,4-cyclohexanedimethanol, based on the total amount of polyol. 
     The 1,3- and 1,4-cyclohexanedimethanol generally comprise a mixture of cis- and trans-forms of the molecule. Preferably, both the 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol independently comprise 35 mole % cis- and 65 mole % trans-forms of the molecules. 
     The NDCA-based polymers made by the processes described above, or by other known processes for the preparation of polyesters, can be combined to form novel, useful compositions. The novel polymers may be combined with alternate novel polymers, or with known polyesters, or with both alternate novel polymers and known polyesters. The present invention includes compositions comprising (1) one or more first polymer comprising reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide, and (2) one or more second polymer selected from the group consisting (A) of polymers of (1) above different from the first polymer and (B) other polyesters which are reaction product of (i) acids or esters and (ii) polyols, wherein (x) the acids and esters do not include NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, when the polyol comprises isosorbide, and (y) wherein the polyols do not include isosorbide when the acids and esters comprise NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof. 
     Preferably, this composition comprises two or more polymers, wherein at least one polymer is the reaction product of a diacid and at least one other polymer is the reaction product of a diester. This composition may comprise two or more polymers, wherein at least one polymer is the reaction product of NDCA, and at least one other polymer is the reaction product of C 1  to C 10  alkyl alkyl diester(s) of NDCA or combinations thereof. 
     The composition may comprise one or more other polyester comprising a reaction product of component (i) FDCA, C 1  to C 10  alkyl alkyl diester thereof, or glycolide, and component (ii) one or more polyol comprising ethylene glycol, a mixture of 1,3- and 1,4-cyclohexanedimethanol, or 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or combinations thereof. 
     The other polyester used in forming the compositions may be one or more known polyesters, conventional or otherwise, including, but not limited to, aliphatic homopolymer polyglycolide (also known as “polyglycolic acid”) (PGA), polylactide (also known as “polylactic acid”) (PLA), polycaprolactone (PCL), copolymer polyethylene adipate (PEA), polyhydroxyalkanoate (PHA), polyethylene terephthalate (PET), semi-aromatic copolymer PET, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and aromatic copolymers from polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid. 
     The invention further includes articles comprising one or more NDCA-based polymers, or compositions containing them. The polymers and compositions containing the polymers may contain other components such as plasticizers, softeners, dyes, pigments, antioxidants, stabilizers, fillers and the like. Examples of articles include, but are not limited to, thermoformed articles, film, shrink label, retortable packaging, pipe, bottle, profile, molded article, extruded article, fiber, and fabric. Rigid or semi-rigid (i.e., somewhat deformable) bottles and various rigid articles may be made using conventional blow-molding processes well-known in the art. The polymers may be used in forms of application where currently PET, or PEF, or similar polyesters are used. 
     The invention further includes methods of forming films or sheets comprising the steps of (i) extruding a polymer to form an extrudate; (ii) shaping the extrudate by passing it through a flat or annular die; and (iii) cooling the extrudate to form a film or sheet having a machine direction and a cross direction; wherein the polymer comprises reaction product of (a) one or more diacid or diester thereof, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. The method may comprise the further step of orienting the film or sheet in the machine or cross direction, or both. The polymer resin may be processed according to standard processes applicable to other polyesters such as PET and PEF. When the resulting film or sheet is oriented in both the machine and cross directions, such orientation may be imparted sequentially or simultaneously. The barrier film thickness typically ranges from 1 μm to 350 μm. 
     The invention further includes a film or sheet of one or more layers, wherein at least one layer comprises polymer comprising the reaction product of (a) one or more diacid, diester thereof, or glycolide, and (b) one or more polyol, wherein component (a) consists essentially of NDCA, C 1  to C 10  alkyl diester thereof, or combinations thereof, and component (b) comprises isosorbide. Such multilayer films may be prepared according to standard processes applicable to other polyesters such as PET and PEF. 
     Films and resins made from the polymers and compositions of the present invention exhibit a desirable balance of properties, relative to PEF polymers, including improved oxygen, carbon dioxide, and water-vapor permeability, higher glass transition temperature (Tg), and improved chemical, heat and impact resistance. In addition, these polymers can used to form films with high-temperature heat sealability using alternative sealing technologies. 
     These films and resins may be used for various applications which benefit from the combination of properties described above, such as shrink labels, bottles for beverages and other fluids, high-barrier film applications for conventional (i.e., for use in less demanding applications than retort) and retortable packaging, hot-fill packaging, and high-heat (i.e., dry heat) applications, such as oven-proof packaging. These films and resins can be used to form packaging for applications generally served by PET films without the need for additional barriers layers needed with PET-based systems. At similar thicknesses as PET food packaging films, the films and resins of the present invention can be used for long shelf-life packaging for food products and pharmaceuticals, or alternatively can be used at down-gauged levels for food packaging and pharmaceuticals with performance comparable to conventional (but thicker) PET-based systems. These films and resins can be used to form transparent packaging that can provide UV-blocking for food, pharmaceutical and other applications. 
     The polymer can also be used in tape applications, such as the carrier for magnetic tape or backing for pressure sensitive adhesive tapes, for packaging trays and blister packs. The polymer can also be used as substrate in thin film and solar cell applications. 
     The polymer may be used formed into injection molded articles, extruded sheets, profile extruded articles and extruded blow molded articles. The polymers may be used in applications including, but not limited to, medical packaging, shrink labels, rigid laminates (e.g., for furniture), transaction cards (e.g., credit cards), bottles (including so-called clear handleware), housewares, appliances, equipment, and signage. 
     Films and resins of the present invention can be used to form multilayer packaging systems. Because of the high barrier properties (vis-à-vis oxygen, CO 2  and moisture), such multilayer systems can be made without metal foil or metalized polymeric film layers. This enables the construction of transparent or substantially transparent packaging films, a desirable opportunity for marketing food and other products. For example, the invention barrier films may comprise a polyester-based polymer with (a) an O 2  gas permeability of 0.4 cc-mil/100 in. 2  24 hrs atm (7.9 cc 20 μm/m 2  24 hrs atm) at 50% relative humidity (ASTM D-3985) or less, (b) a moisture permeability of 0.5 g mil/100 in. 2  24 hrs atm (9.8 g 20 μm/m 2  24 hrs atm) at 38° C. (ASTM F-1249) or less, and (c) a glass transition temperature (Tg) of 100° C. or higher. The barrier film may further have (x) a Falling dart drop impact (Type A) of 200 g for a 50 μm thick film material at room temperature and 50% relative humidity (ASTM D-1709) or greater, (y) an Elmendorf tear of 400 g for a 50 μm thick film material at room temperature and 50% relative humidity (ASTM D-1922) or greater, or (z) a notched Izod impact of 1.0 J/cm at room temperature and 50% relative humidity (ASTM D-256 for rigid materials) or greater, or combinations thereof. Preferably, the film has properties (a), (b) and (c), and one or more of properties (x), (y) and (z). Such polymers are particularly suitable for food, industrial, consumer, pharmaceutical, medical, and electronic and electronic component packaging applications. 
     The barrier films may preferably comprise a polyester-based polymer with (a) an O 2  gas permeability of 2.5 or less, 2 or less, 1 or less, or 0.5 cc-mil/100 in. 2  24 hrs atm or less (5 or less, 4 or less, 2 or less, or 1 cc 20 μm/m 2  24 hrs atm or less) at 50% relative humidity, (b) a moisture permeability of 0.3 or less, 0.2 or less, or 0.1 g mil/100 in. 2  24 hrs atm or less (6 or less, 4 or less, or 2 g 20 μm/m 2  24 hrs atm or less) at 38° C., and (c) a Tg of 110° C. or higher, or 120° C. or higher, or 100 to 150° C., or 110 to 150° C., or 120 to 150° C. 
     The barrier film may preferably have (x) a Falling dart drop impact (Type A) of 250 or greater, or 300 or greater, or 500 g or greater for a 50 μm thick film material at room temperature and 50% relative humidity, (y) an Elmendorf tear of 450 or greater, or 500 or greater, or 600 g or greater at room temperature and 50% relative humidity, or (z) a notched Izod impact of 1.5 or greater, or 2.0 or greater, or 2.5 or greater, or 3.0 J/cm or greater at room temperature and 50% relative humidity, or combinations of (x), (y) and (z). 
     Each of the various figures for the barrier, Tg and toughness properties described in the preceding three paragraphs may be independently combined to describe films within the scope of the present invention. Merely as an illustration of that point, as one example, the barrier film of the present invention may comprise a polyester-based polymer with (a) an O 2  gas permeability of 2.5 cc-mil/100 in. 2  24 hrs atm (5 cc 20 μm/m 2  24 hrs atm) or less at 50% relative humidity, (b) a moisture permeability of 0.5 g mil/100 in. 2  24 hrs atm (9.8 g 20 μm/m 2  24 hrs atm) or less at 38° C., and (c) a Tg of 120° C. or higher; and that barrier film may further have (x) a Falling dart drop impact (Type A) of 250 g or greater for a 50 μm thick film material at room temperature and 50% relative humidity, (y) an Elmendorf tear of 600 g or greater at room temperature and 50% relative humidity, and (z) a notched Izod impact of 3 J/cm or greater at room temperature and 50% relative humidity. This illustrates the point that the barrier film may satisfy any combination of the stated measures for properties (a), (b) and (c), and that it may comprise those properties alone or further in combination with one or more of the properties (x), (y) or (z), and any combination of the stated properties for properties (x), (y) and (z). 
     The polymer may form a film with similar or lesser barrier properties as described above, but with one or more of the following properties indicating toughness: 
     (a) a Falling dart drop impact (Type A) of 200 g for a 50 μm thick film material at room temperature and 50% relative humidity (ASTM D1709) or greater;
 
(b) an Elmendorf tear of 400 g for a 50 μm thick film material at room temperature and 50% relative humidity (ASTM D-1922) or greater; or
 
(c) a notched Izod impact of 1.0 J/cm at room temperature and 50% relative humidity (ASTM D-256 for rigid materials) or greater; or combinations thereof.
 
     The following examples illustrate the present invention. 
     Examples 
     A typical synthesis procedure could be as follows: 
     DMF (2,5-dimethyl furandicarboxylate), the selected diol and ethylene glycol are charged into a reactor with vigorous mixing in presence of a catalyst like monobutyltin oxide and titanium n-butoxide under nitrogen. The temperature of the contents is slowly increased to 160° C. and kept at that temperature for about an hour while collecting methanol through a side-arm attached to vacuum. The temperature is then increased to 170° C. for an hour, followed by at 185° C. for two hours. The vacuum is slowly applied and is reduced to about 1 bar over about 1 hour or more. Finally, the temperature is further increased to 230° C. for about 4 hrs, followed by cooling to about ambient temperature. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
               
               
                   
                   
                   
                   
                   
                 Equivalent % 
               
               
                   
                   
                 Other 
                   
                   
                 Ethylene 
               
               
                   
                 Diacid/ 
                 Diacid/ 
                 Required 
                 Other 
                 glycol in 
               
               
                 Ex. 
                 Diester 
                 Diester 
                 Polyol 
                 Polyol 
                 polyol blend 
               
               
                   
               
             
            
               
                 1 
                 DMN 
                   
                 Isosorbide 
                   
                   
               
               
                 2 
                 DMN 
                 DMF (0.5 
                 Isosorbide 
                 Ethylene 
                 50 
               
               
                   
                   
                 equiv. %) 
                   
                 Glycol 
               
               
                 3 
                 NDCA 
                   
                 Isosorbide 
               
               
                 Comp. 
                 DMN 
                   
                   
                 Ethylene 
               
               
                   
                   
                   
                   
                 Glycol 
               
               
                   
               
            
           
         
       
     
     The comparative example incorporates only DMN and excess ethylene glycol in the process of the above example. 
     Analytical: MW Measurements: 
     HPLC by Waters. 
     Detector: A differential refractometer
 
Eluent: A 5-Mm solution of sodium trifluoroacetate in hexafluoroisopropanol
 
Flow rate: 1.0 ml/min
 
     Column Temperature: 40° C. 
     Standard: Polymethyl methacrylate (PMMA) resin. 
     Forming the Film 
     The polyester-based polymers with the compositions as described in the preparations above may be formed into biaxially-oriented films as follows:
         the polymer is sufficiently dried and extruded onto casting drum (provides smooth surface to plastic film).   the resulting film is stretched 2 to 7 times in both the forward and transverse directions, either in a simultaneous process or sequentially
           Sequential Draw process: the film&#39;s forward draw is over a series of precision motorized rollers; transverse or sideways draw uses diverging clips in a multiple zoned oven with tightly controlled temperatures   Simultaneous Draw process: the film is drawn using precision controlled simultaneously diverging, and accelerating clips through a multiple zoned oven with tightly controlled temperatures   tension and temperatures are maintained properly to ensure final quality of the film   
           the film is wound into large master rolls, which can optionally be slit to precision widths   the film thickness typically ranges from 1 μm to 350 μm.