Process for preparing poly(trimethylene furandicarboxylate)

Abstract

Disclosed herein is a method comprising: a) contacting a mixture comprising furandicarboxylic acid dialkyl ester, 1,3-propanediol, and a metal catalyst at a temperature in the range of from 160 °C to 220 °C to form a prepolymer, wherein the molar ratio of the furandicarboxylic acid dialkyl ester to the 1,3-propanediol is in the range of from 1:1.3 to 1:2.2, and the concentration of metal catalyst is in the range of from 20 ppm to 400 ppm based on the total weight of the mixture; b) removing at least a portion of unreacted 1,3-propanediol; and c) heating the prepolymer to a temperature in the range of from 230 °C to 260 °C under reduced pressure to form a poly(trimethylenefurandicarboxylate) polymer while removing 1,3-propanediol. The poly(trimethylenefurandicarboxylate) polymer.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 408,095, filed October 14, 2016, the contents of which are incorporated by reference in their entirety. TECHNICAL FIELD

[0003] The disclosure herein relates to a composition comprising poly(trimethylene furandicarboxylate) and a process for making the poly(trimethylene furandicarboxylate) polymer of the composition. BACKGROUND

[0004] Polyesters are an important class of industrially significant polymers. Polyesters are used in many industries, including clothing, carpeting, packaging films, coatings, electronics, and transportation. Typically, polyesters are produced by condensing one or more diacids or diesters thereof with one or more diols, where the starting materials are derived from petroleum.

[0005] Poly(trimethylene furandicarboxylate) (PTF) is an important new polymer where the starting materials, furandicarboxylic acid or esters thereof and 1,3-propanediol, can be produced from a biomass feed. Furandicarboxylic acid (FDCA) can be produced from the oxidation of hydroxymethylfurfural, which is readily available from many sources such as biomass and / or high fructose corn syrup, and 1,3-propanediol can be produced by fermentation of sugars. Both of these materials are renewable materials that are produced in industrially significant quantities.

[0006] While PTF can be made from 100% renewable materials, production of the polymer has presented significant challenges. Some of the challenges are (i) producing a polymer with a desired molecular weight, high stability, and low color from melt polymerization, (ii) the polymer produced from melt polymerization is predominantly amorphous, does not have a melting temperature, (iii) the melt polymer can be crystallizable by heating, but the crystallization rate of the polymer is very low, (iv) building high molecular weight from the melt polymer is very time consuming and this step is quite expensive due to the low melting temperature of the crystallizable polymer and the relatively low volatility of the 1,3-propanediol byproduct. There is a need for improved PTF polymer compositions with higher molecular weight, higher stability, faster crystallization rate, and improved color and processes for making such PTF polymers from melt polymerization. SUMMARY

[0007] Disclosed herein is a composition comprising: a poly(trimethylene furandicarboxylate) polymer comprising:

[0008] i) from 95% to 99.9% by weight of trimethylene furandicarboxylate repeat units;

[0009] ii) less than or equal to 1 % by weight of di-PDO repeat units in the polymer backbone;

[0010] iii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0011] iv) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0012] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0013] vi) less than or equal to 1 % by weight of cyclic dimer oligoesters;

[0014] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0015] viii) an intrinsic viscosity ranging from 0.70 to 1.2 dL / g;

[0016] wherein the weight percentages are based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition.

[0017] In another embodiment, the dialkyl furandicarboxylate is dimethyl 2,5- furandicarboxylate.

[0018] In yet another embodiment, the poly(2,5-trimethylene furandicarboxylate) polymer has a crystallization half-time of less than or equal to 100 minutes measured at 120 °C.

[0019] In one embodiment, the composition has a b* color value of less than or equal to 15 as determined by spectral colorimetry. In another embodiment, the composition has a b* color value of less than 10 as determined by spectral colorimetry. In yet another embodiment, the composition has an L* color value of greater than or equal to 60 as determined by spectral colorimetry. In one embodiment, the dialkyl furandicarboxylate is dimethyl 2,5-furandicarboxylate.

[0020] In another embodiment, the composition further comprises one or more additives including a thermal stabilizer, a UV absorber, an antioxidant, a nucleating agent, a processing aid, a hueing agent / optical brightener, an oxygen barrier additive, a chain extender, a chain terminator, a reheat agent, or a light blocker.

[0021] Also disclosed herein is a method comprising:

[0022] a) contacting a mixture comprising furandicarboxylic acid dialkyl ester, 1,3-propanediol, and a metal catalyst at a temperature in the range of from 160 °C to 220 °C to form a prepolymer,

[0023] wherein the molar ratio of the furandicarboxylic acid dialkyl ester to the 1,3-propanediol is in the range of from 1 : 1.3 to 1 : 2.2, and

[0024] the concentration of the metal catalyst is in the range of from 20 ppm to 400 ppm based on the total weight of the mixture;

[0025] b) removing at least a portion of unreacted 1,3-propanediol; and

[0026] c) heating the prepolymer to a temperature in the range of from 230 °C to 260 °C under reduced pressure to form a poly(trimethylenefurandicarboxylate) polymer while removing 1,3-propanediol.

[0027] In one embodiment, the process is batch, semi-continuous, or continuous. In another embodiment, at least 50% by weight of the excess 1,3-propanediol is removed in step b). In yet another embodiment, at least 90% by weight of the excess 1,3-propanediol is removed in step b).

[0028] In further embodiments, step a) optionally includes simultaneously removing at least a portion of the alkyl alcohol formed. In another embodiment, the process further comprises step d) crystallizing the poly(trimethylenefurandicarboxylate) polymer at a temperature in the range of from about 110 °C to about 130 °C to obtain a crystallized poly(trimethylenefurandicarboxylate) polymer.

[0029] Also disclosed herein is a poly(trimethylenefurandicarboxylate) polymer obtained by the process disclosed herein. In yet another embodiment, the poly(trimethylenefurandicarboxylate) polymer obtained by the process disclosed herein comprises:

[0030] i) from 95% to 99.9% by weight of trimethylenefurandicarboxylate repeat units;

[0031] ii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0032] iii) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0033] iv) less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone;

[0034] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0035] vi) less than or equal to 1 % by weight of cyclic dimer oligoesters;

[0036] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0037] viii) an intrinsic viscosity ranging from 0.60 to 1.20 dL / g;

[0038] wherein the weight percent is based on the total weight of the poly(trimethylene furandicarboxylate) polymer.

[0039] Also disclosed herein is a composition comprising: a poly(trimethylene furandicarboxylate) polymer comprising:

[0040] i) from 95 % to 99.9 % by weight of trimethylene furandicarboxylate repeat units;

[0041] ii) less than or equal to 1 % by weight of di-PDO repeat units in the polymer backbone;

[0042] iii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0043] iv) less than or equal to 25 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0044] v) less than or equal to 15 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0045] vi) less than or equal to 1 % by weight of cyclic dimer oligoesters;

[0046] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0047] viii) an intrinsic viscosity ranging from 0.60 to 1.2 dL / g;

[0048] wherein the weight percent is based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition.

[0049] In one embodiment, the dialkyl furandicarboxylate is dimethyl 2,5- furandicarboxylate.

[0050] In yet another embodiment, the poly(2,5-trimethylene furandicarboxylate) polymer has a crystallization half-time of less than or equal to 100 minutes measured at 120 °C.

[0051] In one embodiment, the composition has a b* color value less than or equal to 15 as determined by spectrocolorimetry. In another embodiment, the composition has a b* color value less than 10 as determined by spectrocolorimetry. In yet another embodiment, the composition has an L* color value greater than or equal to 60 as determined by spectrocolorimetry. In one embodiment, the furandicarboxylic acid dialkyl ester is dimethyl 2,5-furandicarboxylate.

[0052] In another embodiment, the composition further comprises one or more additives including a thermal stabilizer, a UV absorber, an antioxidant, a nucleating agent, a processing aid, a hueing agent / optical brightener, an oxygen barrier additive, a chain extender, a chain terminator, a reheat agent, or a light blocker.

[0053] Also disclosed herein are poly(trimethylenefurandicarboxylate) polymers obtained by the methods disclosed herein. In yet another embodiment, the poly(trimethylenefurandicarboxylate) polymers obtained by the methods disclosed herein comprise:

[0054] ix) from 95% to 99.9% by weight of trimethylenefurandicarboxylate repeat units;

[0055] x) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0056] xi) less than or equal to 25 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0057] xii) less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone;

[0058] xiii) less than or equal to 15 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0059] xiv) less than or equal to 1% by weight of cyclic dimer oligoester;

[0060] xv) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0061] xvi) an intrinsic viscosity ranging from 0.60 to 1.20 dL / g;

[0062] wherein the weight percentages are based on the total weight of the poly(trimethylenefurandicarboxylate) polymer. DETAILED DESCRIPTION

[0063] All patents, patent applications, and publications cited herein are hereby incorporated by reference in their entirety.

[0064] As used herein, the terms “embodiment” or “disclosure” are not intended to be limiting, but are typically applicable to any embodiment defined in the claims or described herein. These terms are used interchangeably herein.

[0065] In the present disclosure, a number of terms and abbreviations are used. The following definitions apply unless otherwise explicitly stated.

[0066] The articles “a,” “an,” and “the” preceding an element or component are intended to be non-limiting regarding the number of instances of that element or component. In this regard, “a” or “an” and “the” are to be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is clearly specified.

[0067] The term “comprising” means that the specification is to be interpreted as including the mentioned features, integers, steps, or components, but not precluding the presence or addition of one or more other features, integers, steps, components, or groups thereof. The term “comprising” is intended to include embodiments falling within the scope of the term “consisting essentially of” and “consisting of”. Similarly, the term “consisting essentially of’ is intended to include embodiments falling within the scope of the term “consisting of”.

[0068] Where present, all ranges are inclusive and combinable. For example, when a range of “1 to 5” is recited, the recited range should be interpreted as including ranges of “1 to 4,” “1 to 3,” “1-2,” “1-2 and 4-5,” “1-3 and 5,” etc.

[0069] As used herein, the term “about” in reference to a numerical value means + / - 0.5 of the indexed value, unless the term is otherwise specifically defined in the context. For example, the phrase “a pH of about 6” means a pH from 5.5 to 6.5, unless the pH is otherwise specifically defined.

[0070] Every maximum numerical limitation given throughout this specification is intended to include every lower numerical limitation, as if such lower numerical limitations were expressly written herein. Every minimum numerical limitation given throughout this specification is intended to include every higher numerical limitation, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this specification is intended to include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were expressly written herein.

[0071] The features and advantages of the present disclosure will be more readily understood by persons of ordinary skill in the art upon reading the following detailed description of certain embodiments, with reference made to the accompanying drawings. It is expressly understood that certain features and / or embodiments described in the context of separate embodiments can be provided in a single element in combination with one another. Conversely, various features and / or elements described in the context of a single embodiment can also be provided separately or in any appropriate subcombination. Further, reference to singular can also include the plural (for example, a reference to one can include one or more) unless the context clearly indicates otherwise.

[0072] The use of the terms“about” and“substantially” to describe the usage of a numerical value within a range is stated as an approximation, as both the minimum and maximum values of the range are included. In this manner, slight variations above and below the stated range can be used to achieve substantially the same result as the values within the range. Further, the disclosure of ranges is intended to be a continuous range including every value and sub-range within the minimum and maximum values. The disclosure of ranges is simply intended to serve as a shorthand for this disclosure unless otherwise indicated or unless it would be clear to those skilled in the art that the disclosure of a specific range was intended to be more limited than that.

[0073] As used herein:

[0074] The phrase“poly(trimethylenefurandicarboxylate)” or PTF means a polymer comprising repeat units derived from 1,3-propanediol and furandicarboxylic acid. In some embodiments, the poly(trimethylenefurandicarboxylate) comprises greater than or equal to 95 mole percent repeat units derived from 1,3-propanediol and furandicarboxylic acid. In still further embodiments, the mole percent of 1,3-propanediol and furandicarboxylic acid repeat units is greater than or equal to 95 mole percent or 96 mole percent or 97 mole percent or 98 mole percent or 99 mole percent, where the mole percent is based on the total amount of monomers that form the poly(trimethylenefurandicarboxylate). In some embodiments, the furandicarboxylic acid is 2,3-furandicarboxylic acid, 2,4-furandicarboxylic acid, 2,5-furandicarboxylic acid, or a combination thereof. In other embodiments, the furandicarboxylic acid is 2,5-furandicarboxylic acid.

[0075] The term“trimethylenefurandicarboxylate repeat unit” means a polymer having a structure consisting of alternating furandicarboxylate and -CH2CH2CH2O- groups as repeat units, where“furandicarboxylate” encompasses furan-2,3-dicarboxylate, furan-2,4-dicarboxylate, and furan-2,5-dicarboxylate. The molecular weight of this repeat unit is 196 g / mole. The term“trimethylenefuran-2,5-dicarboxylate repeat unit” means a polymer having a structure consisting of alternating furan-2,5-dicarboxylate and -CH2CH2CH2O- groups as repeat units according to Formula (I):

[0076]

[0077] Similarly, the term "furan-2,4-dicarboxylic acid trimethylene ester repeat unit" means a polymer having a structure consisting of alternating furan-2,4-dicarboxylate and -CH2CH2CH2O- groups as repeat units, and the term "furan-2,3-dicarboxylic acid trimethylene ester repeat unit" means a polymer having a structure consisting of alternating furan-2,3-dicarboxylate and -CH2CH2CH2O- groups as repeat units.

[0078] The number of furandicarboxylic acid trimethylene ester repeat units in a polymer can depend on the change in intrinsic viscosity.

[0079] The phrases "polymer backbone" and "backbone of a polymer" are used interchangeably herein and mean that two or more monomeric units are covalently linked together to produce a continuous polymer chain.

[0080] As used herein, the phrase "end group" means a reactive or non-reactive functional group present at the end of a polymer backbone.

[0081] The phrase "di-propylene glycol" or "di-PDO" repeat unit or end group of a polymer means a unit having a structure according to formula (II):

[0082]

[0083] where P is a poly(furan dicarboxylic acid trimethylene ester) and X is P or hydrogen. The di-PDO group can be an end group, where X is hydrogen, or the di-PDO group can be a repeat unit within the polymer backbone, where X is P.

[0084] The phrase "allyl end group" means an allyl group at the end of a poly(furan dicarboxylic acid trimethylene ester) polymer, for example according to formula (III):

[0085]

[0086] where P represents a poly(furan dicarboxylic acid trimethylene ester) polymer.

[0087] The phrase "alkyl ester end group" means an alkyl ester group at the end of a poly(furan dicarboxylic acid trimethylene ester) polymer. In some embodiments, the alkyl end group can be a methyl, ethyl, propyl, or butyl group.

[0088] The phrase "hydroxyl end group" means a hydroxyl group at the end of a poly(furan dicarboxylic acid trimethylene ester) polymer. The phrase "carboxylic acid end group" means a carboxylic acid group at the end of a poly(furan dicarboxylic acid trimethylene ester) polymer.

[0089] The phrase "cyclic oligoester" means a cyclic compound composed of from two to eight repeating units of the structure according to Formula (I). The phrase "cyclic dimer oligoester" means a dimer having the structure according to Formula (IV):

[0090]

[0091] Other cyclic oligoesters include trimers, tetramers, pentamers, hexamers, heptamers, and octamers having repeating units of Formula (I).

[0092] The phrase "furandicarboxylic acid" encompasses 2,3-furandicarboxylic acid; 2,4- furandicarboxylic acid; and 2,5-furandicarboxylic acid. In an embodiment, the furandicarboxylic acid is 2,3-furandicarboxylic acid. In an embodiment, the furandicarboxylic acid is 2,4- furandicarboxylic acid. In an embodiment, the furandicarboxylic acid is 2,5-furandicarboxylic acid.

[0093] The phrase "dialkyl furandicarboxylate" means a dialkyl ester of furandicarboxylic acid. In some embodiments, the dialkyl furandicarboxylate can have the structure according to Formula (V):

[0094]

[0095] where each R is independently a Ci to Cs alkyl group. In some embodiments, each R is independently a methyl, ethyl, or propyl group. In another embodiment, each R is a methyl group and the dialkyl furandicarboxylate is dimethyl 2,5-furandicarboxylate (FDME). In another embodiment, each R is an ethyl group and the dialkyl furandicarboxylate is diethyl 2,5-furandicarboxylate.

[0096] The terms "a* value," "b* value," and "L* value" mean colors according to the CIE L*a*b* color space. The a* value indicates the degree of red (positive value) or green (negative value). The b* value indicates the degree of yellow (positive value) or blue (negative value). The L* value indicates the lightness of the color space, where 0 indicates black and 100 refers to a diffusely white color.

[0097] The term "prepolymer" means a relatively low molecular weight compound or oligomer having at least one furandicarboxylate trimethylene repeating unit. Typically, the prepolymer has a molecular weight in the range from about 196 g / mole to about 6000 g / mole. The smallest prepolymer will typically be bis(l,3-propanediol) furandicarboxylate, while the largest prepolymer can have in the range from 2 to 30 furandicarboxylate trimethylene repeating units. In an embodiment, the prepolymer has a molecular weight in the range from about 214 g / mole to about 6000 g / mole.

[0098] The phrase "removing at least a portion of" means a process in which at least 50% by weight of the recited component is removed from an initial mixture containing that component prior to the start of the removal process. In other embodiments, at least 60% or 70% or 80% or 90% or 91% or 92% or 93% or 94% or 95% or 96% or 97% or 98% or 99% or 99.5% or 99.9% of the recited component is removed. The weight percent is based on the excess of the recited component prior to the start of the removal process.

[0099] As used herein, "weight average molecular weight" or "M w "

[0100] M w =∑N i M i 2 / ∑N i M i ; where M i is the molecular weight of a chain and N i is the number of chains having that molecular weight. Weight average molecular weight can be determined by techniques such as gas chromatography (GC), high pressure liquid chromatography (HPLC), and gel permeation chromatography (GPC).

[0101] As used herein, "number average molecular weight" or "M n " refers to the statistical average molecular weight of all the polymer chains in a sample. The number average molecular weight is calculated as M n =∑N i M i / ∑N i , where M i is the molecular weight of a chain and N i is the number of chains having that molecular weight. The number average molecular weight of a polymer can be determined by techniques such as gel permeation chromatography, viscosity determination via the (Mark-Houwink equation), and colligative methods such as vapor pressure osmometry, end-group determination, or proton NMR.

[0102] In some embodiments, the present disclosure relates to a composition comprising:

[0103] a poly(trimethylenefurandicarboxylate) polymer comprising:

[0104] i) from 95% to 99.9% by weight of trimethylenefurandicarboxylate repeat units;

[0105] ii) less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone;

[0106] iii) less than or equal to 20 milliequivalents (meq) of allyl end groups per kilogram of polymer;

[0107] iv) less than or equal to 15 meq of carboxylic acid end groups per kilogram of polymer;

[0108] v) less than or equal to 10 meq of alkyl ester end groups per kilogram of polymer;

[0109] vi) less than or equal to 1.0% by weight of at least one cyclic oligoester; and

[0110] vii) less than or equal to 10 meq of di-PDO end groups per kilogram of polymer; and

[0111] viii) an intrinsic viscosity ranging from 0.70 to 1.2 dL / g;

[0112] wherein the weight percent is based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition.

[0113] The poly(trimethylene furandicarboxylate) polymer can be produced by a method comprising:

[0114] a) contacting a mixture comprising dialkyl furandicarboxylate, 1,3-propanediol, and a metal catalyst at a temperature ranging from 160 °C to 220 °C to form a prepolymer, wherein the molar ratio of the dialkyl furandicarboxylate to the 1,3-propanediol ranges from 1 : 1.3 up to 1 : 2.2 and the concentration of metal catalyst ranges from 20 ppm to 200 ppm based on the total weight of the mixture;

[0115] b) removing at least a portion of unreacted 1,3-propanediol; and

[0116] c) heating the prepolymer to a temperature ranging from 230 °C to 260 °C under reduced pressure to form a poly(trimethylene furandicarboxylate) while removing 1,3-propanediol.

[0117] The weight percent of trimethylene furandicarboxylate repeat units, the amount of di-PDO repeat units in the polymer backbone, the type and amount of end groups, and cyclic oligoester groups can be determined by, for example, proton NMR. The amount of carboxylic acid end groups can also be determined by proton NMR, for example, by derivatizing the carboxylic acid end groups with trifluoroacetic anhydride or by titration.

[0118] The percentage of furandicarboxylic acid trimethylene ester repeat units can range from 95% to 99.9% by weight, based on the total amount of poly(triethylene furandicarboxylate) in the composition. In other embodiments, the furandicarboxylic acid trimethylene ester repeat units can be present in an amount ranging from 96% to 99.9% or 97% to 99.9% or 98% to 99.9% or 99% to 99.9% by weight. All percentages are based on the total weight of poly(triethylene furandicarboxylate) in the composition.

[0119] In some embodiments, the poly(triethylene furandicarboxylate) polymer has a b* color value less than 15 as determined by spectral colorimetry. In some embodiments, the poly(triethylene furandicarboxylate) polymer has an intrinsic viscosity ranging from 0.60 to 1.2 dL / g. In some embodiments, the L* color value of the poly(triethylene furandicarboxylate) is greater than 60. In some embodiments, the poly(triethylene furandicarboxylate) polymer has a crystallization half-time (t 1 / 2 ) of less than or equal to 100 minutes, for example, less than 50 minutes, or less than 40 minutes, or less than 35 minutes, measured at 120 °C.

[0120] Like other polyesters, the properties of poly(triethylene-2,5-furandicarboxylate) polymers (PTF) depend on, for example, its structure, composition, molecular weight, and crystallinity characteristics. In addition, the type and amount of catalyst and additives also vary the properties of the polymer. Generally, the higher the molecular weight, the better the mechanical properties. In many processes for making high molecular weight polyesters, the polyester is prepared in a two-stage melt polymerization, which includes direct esterification or ester exchange (transesterification) and polycondensation at one or more temperatures above the melting temperature of the final polymer, followed by solid state polymerization at one or more temperatures below the melting temperature of the polymer. However, because the melting temperature of crystalline PTF polymers is relatively low (< 18 °C) and the boiling point of the reaction byproduct (1,3-propanediol) is high (214 °C), it takes a much longer time to build high molecular weight in the solid state polymerization step, which makes the solid state polymerization process expensive, less productive, and impractical.

[0121] As disclosed herein, PTF polymers having an intrinsic viscosity of 0.70 to 1.2 dL / g and / or a number average molecular weight of at least 15,000 g / mole are prepared in a melt polymerization process without solid state polymerization. As disclosed herein, the PTF polymers have an intrinsic viscosity of 0.60 to 1.2 dL / g. In some embodiments, the process can be a continuous process. In other embodiments, the process can be a batch process, or a semi-batch process.

[0122] The molecular weight of the PTF polymer can be measured by different techniques, such as proton NMR providing number average molecular weight from end group analysis, size exclusion chromatography providing number average molecular weight and weight average molecular weight, and intrinsic viscosity. The intrinsic viscosity of the PTF polymer produced according to the disclosed process can be measured by standard methods, such as disclosed in the experimental section below, and can be in the range from 0.70 to 1.20 dL / g. In other embodiments, the intrinsic viscosity can be in the range from 0.60 to 1.20 dL / g or 0.70 to 1.00 dL / g, or 0.70 to 0.90 dL / g, or 0.70 to 0.80 dL / g or 0.65 to 1.00 dL / g, or 0.70 to 0.95 dL / g, or 0.70 to 0.90 dL / g. The number average molecular weight (Mn) of the PTF polymer produced according to the disclosed process can be in the range from 15,000 to 40,000 g / mole. In other embodiments, the number average molecular weight can be in the range from 12,000 to 40,000 g / mole or 15,000 to 30,000 g / mole or 15,000 to 25,000 g / mole. The weight average molecular weight (Mw) of the PTF polymer can be in the range from 24,000 to 80,000 g / mole, or 30,000 to 80,000 g / mole, or 30,000 to 70,000 g / mole or 30,000 to 60,000 g / mole. n w

[0123] Differential scanning calorimetry (DSC) shows that the PTF polymer prepared using the disclosed melt polymerization process does not have a melting point when the polymer sample is heated at 10 °C / min, which indicates that the polymer is predominantly in an amorphous state. To produce a crystalline PTF polymer, the amorphous PTF polymer is heated to a cold crystallization temperature, for example, heated to a temperature in the range from 100 °C to 130 °C to obtain a crystalline PTF polymer from which a melting point can be determined. The melting temperature of the crystalline PTF polymer depends on the molecular structure of the repeat unit I, and the crystallization rate and morphology. As the molecular weight of the PTF polymer increases, the crystallization rate decreases and thus the melting temperature decreases. The melting temperature (Tm) and enthalpy or heat of fusion (AHf) of the formed crystals can be determined by DSC. The melting temperature (Tm) of the formed crystals can be in the range from 150 °C to 200 °C, or 155 °C to 195 °C, or 160 °C to 190 °C, or 165 °C to 185 °C, or 170 °C to 180 °C. The heat of fusion (AHf) of the formed crystals can be in the range from 10 J / g to 50 J / g, or 15 J / g to 45 J / g, or 20 J / g to 40 J / g, or 25 J / g to 35 J / g. m m ​​​) measured by the cold-heat cycle and heat cycle of DSC. The heat of fusion of a pure crystalline polymer is an important parameter that can be used with the theoretical heat of fusion of 100% crystalline PTF to estimate the degree of crystallinity of the polymer. The percent crystallinity is directly related to many key properties exhibited by semi-crystalline polymers, including: brittleness, toughness, stiffness or modulus, optical clarity, creep or cold flow, barrier resistance (ability to prevent gas transmission in or out) and long term stability.

[0124] Crystalline PTF polymers can have a broad melting temperature range (multiple peaks in DSC) when the polymer is heated at 10 °C / min, while a single narrow peak can be obtained when the polymer is heated at a very slow rate, e.g., 1 °C / min. The melting temperature of the main peak of a crystalline PTF polymer is measured from the first heating DSC scan and is in the range from 155 °C to 185 °C, preferably from 165 °C to 185 °C. The glass transition temperature of the polymer is obtained in the second heating DSC scan at a rate of 10 °C / min and is in the range from 57 °C to 62 °C.

[0125] The physical, mechanical and optical properties of crystalline PTF are strongly dependent on the morphological characteristics of the polymer, such as polymer size, shape, integrity, orientation, and / or volume fraction. The crystallization rate is typically expressed by using the isothermal half-crystallization time (t 1 / 2 ) values in minutes or seconds at a specific temperature, and can be obtained from DSC experiments. The isothermal crystallization temperature is between the glass transition temperature (T g ) and the melting point (T m ) of the PTF polymer and can be measured at different temperatures ranging from 70 °C - 160 °C. After isothermal melt crystallization, the subsequent DSC heating trace can provide information on the melting behavior of the polymer. The half-crystallization time and crystallization rate depend on factors such as the crystallization temperature of the polymer, average molecular weight, molecular weight distribution, chain structure, presence of any comonomer, nucleating agents, and plasticizers. Increasing the molecular weight in a melt polymerization process decreases the crystallization rate, and thus polymers made from the melt are predominantly amorphous. In general, polymers with slow crystallization rates find limited use in engineering and packaging applications.

[0126] 1,3-propanediol dimer (di-PDO) is a glycol ether produced from 1,3-propanediol through an acid catalyzed side reaction between two glycol molecules or between a glycol and a diol end group in a prepolymer or polymer. Typically, when the monomer is a dialkyl ester rather than a dicarboxylic acid, the amount of ether present in the polymer backbone is typically low (<1 wt%). Unexpectedly, the amount of ether present in polytrimethylenefurandicarboxylate prepared from dimethyl 2,5-furandicarboxylate is unexpectedly high (greater than 3 wt%). As 1,3-propanediol dimer (di-PDO) in the polymer backbone can adversely affect the structure and properties of PTF polymers. For example, depending on the amount of ether in the polymer backbone, its glass transition temperature, melting temperature can be lower, crystallinity and crystallization rate can be lower and thermal stability and thermal oxidative stability can be lower, color chromophore and propenal production can be higher, PTF polymers with low di-PDO content are desirable. Without the addition of any additives to inhibit ether formation, PTF polymers prepared according to the melt polymerization process disclosed herein can contain very low levels of di-PDO in the polymer backbone, for example less than about 2% by weight based on the total weight of the poly(trimethylenefurandicarboxylate) polymer. In some embodiments, the PTF polymer comprises less than or equal to 1.5% by weight of di-PDO repeat units in the polymer backbone, or less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone, or less than or equal to 0.5% by weight of di-PDO repeat units in the polymer backbone, where the weight percentages are based on the total weight of the polymer.

[0127] Polyesters prepared from melt polymerization processes are known to contain cyclic oligomeric esters as impurities. In the case of poly(ethylene terephthalate), the majority of the cyclic oligomeric esters are cyclic trimers that are typically present at levels of 2% to 4% by weight. In contrast, in the case of poly(trimethyleneterephthalate), the main class of cyclic oligomeric esters is cyclic dimers that can be present in the polymer at 2.5% or more by weight. Cyclic oligomeric ester impurities can be problematic during polymerization, processing, and in end-use applications such as injection molded parts, apparel fibers, filaments, and films. Reducing the concentration of cyclic oligomeric esters in the polymer can positively impact polymer production, for example through extended wipe cycle times during fiber spinning, reduced oligomer blooming of injection molded parts, and reduced haze of films.

[0128] One way to reduce the content of cyclic oligoesters in polyesters such as poly(ethylene terephthalate) and poly(trimethylene terephthalate) is through the use of solid state polymerization. However, we have surprisingly found that high molecular weight PTF polymers obtained from the melt polymerization processes disclosed herein contain very low levels of cyclic oligoesters even in the absence of a solid state polymerization step. The predominant cyclic oligoester in the PTF polymers is the cyclic dimer. The total amount of cyclic esters, including dimers, in the polymer can be determined by proton NMR analysis as described in the experimental section. The PTF polymers obtained by the processes disclosed herein can contain less than 2% by weight, for example, less than 1.5% by weight, or less than 1% by weight, or less than 0.5% by weight of cyclic dimer oligoesters based on the total weight of the PTF polymer. The amount of cyclic oligoesters in the polymer can be less than 1.0% by weight based on the total weight of the poly(trimethylene furandicarboxylate) polymer. In other embodiments, the amount of cyclic oligoesters can be less than 0.9% or 0.8% or 0.7% or 0.6% or 0.5% or 0.4% or 0.3% or 0.2% or 0.1% by weight based on the total weight of the poly(trimethylene furandicarboxylate) polymer.

[0129] The poly(trimethylene furandicarboxylate) polymer can contain end groups other than hydroxyl groups, such as allyl, carboxylic acid, dicarboxylic acid, alkyl ester, aldehyde, and ether end groups resulting from thermal degradation and thermal-oxidative degradation of the polymer chain, other side reactions during the melt polymerization conditions, and impurities in the one or more monomers. The PTF polymers prepared according to the present disclosure have a majority of hydroxyl ends and a relatively low amount of these other end groups.

[0130] In one embodiment, in step a) of the process, the mixture consisting of or consisting essentially of dialkyl furandicarboxylate, 1,3-propanediol, and metal catalyst is contacted at a temperature in the range of from 160°C to 220°C to form a prepolymer. By "consisting essentially of" it is meant that there is less than or equal to 1% by weight of other diester, diacid, or polyol monomers in the mixture that are not furandicarboxylate or 1,3-propanediol. In other embodiments, the mixture contacted in the first step is free or essentially free of acid functional components, for example, acid functional monomers such as furandicarboxylic acid. As used herein, "essentially free" means that the mixture contains less than 5% by weight of acid functional monomers based on the total weight of monomers in the mixture. In other embodiments, the amount of acid functional monomers is less than 4% or 3% or 2% or 1% or the amount of acid functional monomers is 0%. It has been found that the presence of acid during the polymerization process can lead to increased color of the final poly(trimethylene furandicarboxylate), and therefore, the amount of acid should be kept as low as possible.

[0131] The furandicarboxylic acid dialkyl ester can be any known dialkyl ester, such as a furandicarboxylic acid dialkyl ester having from 1 to 8 carbon atoms in the ester group. The term "furandicarboxylic acid dialkyl ester" is used interchangeably herein with the term "furandicarboxylate dialkyl ester." In some embodiments, the furandicarboxylic acid dialkyl ester is dimethyl furandicarboxylate, diethyl furandicarboxylate, dipropyl furandicarboxylate, dibutyl furandicarboxylate, dipentyl furandicarboxylate, dihexyl furandicarboxylate, diheptyl furandicarboxylate, dioctyl furandicarboxylate, or a combination thereof. In other embodiments, the furandicarboxylic acid dialkyl ester is dimethyl furandicarboxylate, diethyl furandicarboxylate, or a mixture of dimethyl furandicarboxylate and diethyl furandicarboxylate. The ester group of the furandicarboxylic acid dialkyl ester can be positioned at the 2,3-, 2,4-, or 2,5- positions of the furan ring. In some embodiments, the furandicarboxylic acid dialkyl ester is a 2,3-furandicarboxylic acid dialkyl ester; a 2,4-furandicarboxylic acid dialkyl ester; a 2,5-furandicarboxylic acid dialkyl ester; or a mixture thereof. In still further embodiments, the furandicarboxylic acid dialkyl ester is a 2,5-furandicarboxylic acid dialkyl ester, and in still further embodiments, it is dimethyl 2,5-furandicarboxylate.

[0132] In the contacting step, the molar ratio of furandicarboxylic acid dialkyl ester to 1,3-propanediol is in the range from 1 : 1.3 to 1 : 2.2. In other words, for every 1 mole of furandicarboxylic acid dialkyl ester, at least 1.3 moles and up to 2.2 moles of 1,3-propanediol can be used. In principle, more than 2.2 moles of 1,3-propanediol can be used for every 1 mole of furandicarboxylic acid dialkyl ester, however, more than 2.2 moles of 1,3-propanediol provides little benefit and can increase the amount of time and energy required for step b), which is removing at least a portion of the unreacted 1,3-propanediol. In other embodiments, the molar ratio of furandicarboxylic acid dialkyl ester to 1,3-propanediol can be in the range from 1 : 1.3 up to 1 : 2.1, or from 1 : 1.3 to 1 : 2.0. In still further embodiments, the ratio of furandicarboxylic acid dialkyl ester to 1,3-propanediol can be in the range from 1 : 1.4 up to 1 : 1.8 or from 1 : 1.5 up to 1 : 1.8.

[0133] The contacting step is in the presence of at least one metal catalyst. The amount of metal in the metal catalyst is in the range of from 20 parts per million (ppm) to 400 ppm by weight, based on 100% of the theoretical yield of the polymer produced. In other embodiments, the amount of metal catalyst present in the contacting step can be in the range of from 25 to 250 ppm, or from 30 to 200 ppm, or from 20 to 200 ppm, or from 40 to 150 ppm, or from 50 to 100 ppm, where the concentration (parts per million) is based on the mixture of the dialkyl furandicarboxylate, 1,3-propanediol, and metal catalyst of the contacting step. Suitable metal catalysts can include, for example, titanium compounds, bismuth compounds such as bismuth oxide, germanium compounds such as germanium dioxide, zirconium compounds such as tetraalkyl zirconate, tin compounds such as butyl stannoic acid, tin oxide and alkyl tin, antimony compounds such as antimony trioxide and antimony triacetate, aluminum compounds such as aluminum carboxylates and aluminum alkoxides, inorganic acid salts of aluminum, cobalt compounds such as cobalt acetate, manganese compounds such as manganese acetate, zinc compounds such as zinc acetate, or combinations thereof. Alternatively, the catalyst can be tetraalkyl titanate Ti(OR)4, for example tetraisopropyl titanate, tetra-n-butyl titanate, tetra(2-ethylhexyl) titanate, titanium chelates, such as acetylacetone titanate, ethyl acetoacetate titanate, triethanolamine titanate, lactic acid titanate, or combinations thereof. Suitable metal catalysts can be commercially obtained or prepared by known methods.

[0134] During the contacting step, the dialkyl furandicarboxylate is transesterified with the 1,3-propanediol, resulting in the formation of bis(1,3-propanediol) furandicarboxylate prepolymers and the alkyl alcohol corresponding to the alcohol of the ester of the furandicarboxylic acid starting material. For example, when dimethyl furandicarboxylate is used, methanol is formed in addition to the prepolymers. The alkyl alcohol is removed by distillation during step a). The contacting step can be carried out at atmospheric pressure, or in other embodiments at slightly elevated or reduced pressure. The contacting step is carried out at a temperature in the range of from 160 °C to 220 °C, for example in the range of from 170 °C to 215 °C or from 180 °C to 210 °C or from 190 °C to 210 °C or 165 °C to 215 °C or from 170 °C to 210 °C or from 180 °C to 210 °C.

[0135] After the prepolymer is formed, at least a portion of the unreacted 1,3-propanediol is removed from the reaction mixture. The removal of the unreacted 1,3-propanediol is typically performed by distillation, for example by reducing the pressure relative to the pressure of the contacting step. In some embodiments, the temperature can be maintained in the range used in the contacting step. In other embodiments, the temperature can be increased to be in the range of from about 180 °C to about 220 °C. In one embodiment, at least 50% by weight of the unreacted 1,3-propanediol is removed. In other embodiments, at least 60% or 65% or 70% or 75% or 80% or 85% or 90% or 95% or 96% or 97% or 98% or 99% by weight of the unreacted 1,3-propanediol is removed. The amount of unreacted 1,3-propanediol present in the reaction mixture after the contacting step is calculated by subtracting the amount of 1,3-propanediol required to produce the prepolymer, assuming the prepolymer is 100% bis(1,3-propanediol) furandicarboxylate, which means two moles of 1,3-propanediol have reacted with each mole of the furandicarboxylic acid dialkyl ester used, from the total amount of 1,3-propanediol added in the contacting step.

[0136] Once at least 50% by weight of the unreacted 1,3-propanediol has been removed, the prepolymer is heated under reduced pressure to a temperature in the range of from 230 °C to 260 °C to form a poly(trimethylenefurandicarbonate) polymer while removing the byproduct 1,3-propanediol. The temperature is typically in the range of from 230 °C to 260 °C, for example from 230 °C to 255 °C or from 230 °C to 250 °C. The pressure can be from less than about one atmosphere to 0.0001 atmosphere. During step c), the prepolymer is subjected to a polycondensation reaction, increasing the molecular weight of the polymer (as indicated by an increasing intrinsic viscosity) and releasing 1,3-propanediol. Step c) can continue at a temperature in the range of from 230 °C to 260 °C for a time such that the intrinsic viscosity of the polymer reaches 0.70 to 1.2 dL / g. The time is typically from 1 hour to several hours, for example 2, 3, 4, 5, 6, 7, 8, 9, or 10 hours or any time in between 1 hour and 10 hours. Once the desired intrinsic viscosity of the polymer is reached, the reactor and its contents can be cooled, for example to room temperature, to obtain the poly(trimethylenefurandicarbonate) polymer. If desired, the 1,3-propanediol removed from steps b) and c) can be recycled into the process. The process steps a), b), and c) can be performed in a batch, semi-continuous, or continuous melt polymerization reactor.

[0137] Optionally, the PTF polymer can then be crystallized at a temperature in the range from about 110°C to 130°C, preferably from about 115°C to 125°C. It is preferred to crystallize the polymer by slowly ramping the temperature from room temperature to the desired temperature of from about 110°C to 130°C. At this temperature range, typical crystallization times are in the range from about one hour to several hours. By heating the polymer at a slower rate of 1 °C per minute relative to 10 °C per minute, the melting temperature of the polymer can be increased from about 170°C to about 180°C. A crystallized polymer having an L* value greater than 60 and a b* color value less than 15 can be obtained. In some embodiments, the b* color value can be less than 10. Solid state polycondensation to increase the intrinsic viscosity to the range of 0.70 to 1.2 dL / g is not required, although an additional polycondensation step can be used if it is desired to have a poly(trimethylene furandicarboxylate) polymer having a viscosity greater than 1.2 dL / g.

[0138] The poly(trimethylene furandicarboxylate) polymers obtained by the methods disclosed herein are relatively free of impurities, particularly color-forming impurities. In one embodiment, the poly(trimethylene furandicarboxylate) polymers obtained by the methods disclosed herein comprise:

[0139] i) from 95% to 99.9% by weight of trimethylene furandicarboxylate repeat units;

[0140] ii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0141] iii) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0142] iv) less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone;

[0143] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0144] vi) less than or equal to 1.0% by weight of cyclic dimer oligomeric esters;

[0145] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0146] viii) an intrinsic viscosity in the range from 0.70 to 1.2 dL / g;

[0147] where the weight percentages are based on the total weight of the poly(trimethylene furandicarboxylate) polymer.

[0148] Allyl end groups are believed to be due to thermal degradation of the polymer chain during the polycondensation stage. In some embodiments, the amount of allyl end groups can be less than 20 milliequivalents per kilogram (meq / kg) of polymer, or less than 19, or 18, or 17, or 16, or 15, or 14, or 13, or 12, or 11, or 10 meq / kg of polymer.

[0149] Carboxylic acid ends are believed to be formed by degradation or side reactions that occur during the increasing molecular weight in the later portion of the polycondensation stage where the temperature is high. Typically, the higher the molecular weight of the polymer, the higher the concentration of carboxylic acid ends. Due to the lower polycondensation temperature, the carboxylic acid end concentration of a solid state polymerized polymer is relatively lower than that of a melt polymerized polymer. In some embodiments, the amount of carboxylic acid end groups can be less than 15 meq / kg of polymer, or less than 14, or 13, or 12, or 11, or 10, or 9, or 8, or 7, or 6, or 5, or 4, or 3, or 2, or 1 meq / kg of polymer.

[0150] To build a high molecular weight polymer in the polycondensation stage, it is desirable to fully transesterify both ester groups of each furandicarboxylate with 1,3-propanediol. In some embodiments, the PTF polymers obtained by the methods disclosed herein do not have alkyl ester end groups as determined by H NMR spectroscopy. In some embodiments, the amount of alkyl ester end groups in the PTF polymer can be less than 10 meq / kg of polymer. The amount of alkyl ester end groups excludes the hydroxyl functional trimethylene end groups from 1,3-propanediol. In other embodiments, the alkyl ester end groups can be less than 9, or 8, or 7, or 6, or 5, or 4, or 4, or 3, or 2, or 1 meq / kg of polymer. 1 H NMR spectroscopy. In some embodiments, the amount of alkyl ester end groups in the PTF polymer can be less than 10 meq / kg of polymer. The amount of alkyl ester end groups excludes the hydroxyl functional trimethylene end groups from 1,3-propanediol. In other embodiments, the alkyl ester end groups can be less than 9, or 8, or 7, or 6, or 5, or 4, or 4, or 3, or 2, or 1 meq / kg of polymer.

[0151] CIE b* color is a measure of both yellow (positive values) and blue (negative values), and b* color values can be less than 0. Typically, it is difficult to produce poly(trimethylenefurandicarboxylate) having a b* color value less than 15 without additional purification steps or without additives that reduce the b* color value. Minimizing the amounts of components ii) through vii) listed above to less than or equal to the amounts listed above can provide poly(trimethylenefurandicarboxylate) polymers having a b* color value less than 15. In some embodiments, the b* color value can be less than 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1. When measuring the b* color value of a poly(trimethylenefurandicarboxylate) polymer, the color value should be measured prior to the addition of any components that can contribute color, except for components known to provide a lower b* color value, such as blue pigments or optical brighteners. In one embodiment, a b* color value less than 15 can be achieved where the poly(trimethylenefurandicarboxylate) polymer is free of blue pigments and / or optical brighteners. In another embodiment, a b* color value less than 15 can be achieved where the poly(trimethylenefurandicarboxylate) polymer contains one or more blue pigments and / or one or more optical brighteners. Suitable blue pigments can include, for example, anthraquinone. Suitable optical brighteners can include, for example, thiophene or KS1P pigments. Blue pigments and optical brighteners are commercially available.

[0152] In some embodiments, the composition comprising the poly(trimethylenefurandicarboxylate) polymer can further comprise one or more additives, such as heat stabilizers, UV absorbers, antioxidants, nucleating agents, processing aids (plasticizers), toners / optical brighteners, oxygen barrier additives, chain extenders, chain terminators, multifunctional branching agents, reheat agents, light blockers, or combinations thereof.

[0153] The PTF polymers disclosed herein are suitable for forming a variety of shaped articles, including films, sheets, tubes, preforms, molded articles, containers, and the like. Suitable methods for forming the articles are known and include extrusion, extrusion blow molding

[0154] melt casting, injection molding, stretch blow molding, and thermoforming.

[0155] Non-limiting embodiments of the disclosure herein include:

[0156] 1. A method comprising:

[0157] a) contacting a mixture comprising dialkyl furandicarboxylate, 1,3-propanediol, and a metal catalyst at a temperature in the range of from 160 °C to 220 °C to form a prepolymer,

[0158] wherein the molar ratio of the dialkyl furandicarboxylate to the 1,3-propanediol is in the range of from 1:1.3 to 1:2.2, and

[0159] the concentration of the metal catalyst is in the range of from 20 ppm to 400 ppm based on the total weight of the mixture;

[0160] b) removing at least a portion of unreacted 1,3-propanediol; and c) heating the prepolymer under reduced pressure to a temperature in the range of from 230 °C to 260 °C to form a poly(trimethylenefurandicarboxylate) polymer while removing 1,3-propanediol.

[0161] 2. The method of embodiment 1, wherein the poly(trimethylenefurandicarboxylate) polymer has a b* color value of less than 15 as determined by spectral colorimetry.

[0162] 3. The method of embodiment 1 or 2, wherein the poly(trimethylenefurandicarboxylate) polymer has an intrinsic viscosity in the range of from 0.70 to 1.2 dL / g.

[0163] 4. The method of embodiment 1, 2, or 3, wherein the method is batch, semi-continuous, or continuous.

[0164] 5. The method of embodiment 1, 2, 3, or 4, wherein at least 50% by weight of the excess 1,3-propanediol is removed in step b).

[0165] 6. The method of embodiment 1, 2, 3, 4, or 5, wherein at least 90% by weight of the excess 1,3-propanediol is removed in step b).

[0166] 7. The method of embodiment 1, 2, 3, 4, 5, or 6, wherein the dialkyl furandicarboxylate is dimethyl 2,5-furandicarboxylate.

[0167] 8. The method of embodiment 1, 2, 3, 4, 5, 6, or 7, wherein the poly(trimethylenefurandicarboxylate) polymer has a crystallization half-time of less than or equal to 100 minutes measured at 120 °C.

[0168] 9. The method of embodiment 1, 2, 3, 4, 5, 6, 7, or 8, wherein step a) further comprises simultaneously removing at least a portion of the formed alkyl alcohol.

[0169] 10. The method of embodiment 1, 2, 3, 4, 5, 6, 7, 8, or 9, further comprising step d) crystallizing the poly(trimethylenefurandicarboxylate) polymer at a temperature in the range of from about 110 °C to about 130 °C to obtain a crystallized poly(trimethylenefurandicarboxylate) polymer.

[0170] 11. A poly(trimethylene furandicarboxylate) polymer obtained by the method of embodiments 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0171] 12. The poly(trimethylene furandicarboxylate) polymer of embodiment 11, wherein the polymer comprises:

[0172] i) from 95% to 99.9% by weight of trimethylene furandicarboxylate repeat units;

[0173] ii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0174] iii) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0175] iv) less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone;

[0176] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0177] vi) less than or equal to 1% by weight of cyclic dimer oligoester;

[0178] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0179] viii) an intrinsic viscosity ranging from 0.70 to 1.20 dL / g;

[0180] wherein the weight percentages are based on the total weight of the poly(trimethylene furandicarboxylate) polymer.

[0181] 13. The poly(trimethylene furandicarboxylate) polymer of embodiment 11, wherein the polymer comprises:

[0182] i) from 95% to 99.9% by weight of trimethylene furandicarboxylate repeat units;

[0183] ii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0184] iii) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0185] iv) less than or equal to 1% by weight of di-PDO repeat units in the polymer backbone;

[0186] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0187] vi) less than or equal to 1 % by weight of cyclic dimer oligoesters;

[0188] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0189] viii) an intrinsic viscosity ranging from 0.60 to 1.20 dL / g;

[0190] wherein the weight percent is based on the total weight of the poly(trimethylene furandicarboxylate) polymer.

[0191] 14. A composition comprising:

[0192] a poly(trimethylene furandicarboxylate) polymer comprising:

[0193] i) from 95% to 99.9% by weight of trimethylene furandicarboxylate repeat units;

[0194] ii) less than or equal to 1 % by weight of di-PDO repeat units in the polymer backbone;

[0195] iii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0196] iv) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0197] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0198] vi) less than or equal to 1 % by weight of cyclic dimer oligoesters;

[0199] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0200] viii) an intrinsic viscosity ranging from 0.670 to 1.2 dL / g;

[0201] wherein the weight percent is based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition.

[0202] 15. A composition comprising:

[0203] a poly(trimethylene furandicarboxylate) polymer comprising:

[0204] i) from 95% to 99.9% by weight of trimethylene furandicarboxylate repeat units;

[0205] ii) less than or equal to 1 % by weight of di-PDO repeat units in the polymer backbone;

[0206] iii) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer;

[0207] iv) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer;

[0208] v) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer;

[0209] vi) less than or equal to 1% by weight of cyclic dimer oligoester;

[0210] vii) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; and

[0211] viii) an intrinsic viscosity ranging from 0.60 to 1.2 dL / g;

[0212] wherein the weight percentages are based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition.

[0213] 16. The composition of Example 14, wherein the composition has a b* color value of less than or equal to 15 as determined by spectrocolorimetry.

[0214] 17. The composition of Example 14 or 15, wherein the composition has a b* color value of less than 10 as determined by spectrocolorimetry.

[0215] 18. The composition of Example 14, 15, or 16, wherein the composition has an L* color value of greater than or equal to 60 as determined by spectrocolorimetry.

[0216] 19. The composition of Example 14, 15, 16, or 17, having an L* color value of greater than or equal to 60 as determined by spectrocolorimetry.

[0217] 20. The composition of Example 14, 15, 16, 17, or 18, wherein the dialkyl furandicarboxylate is dimethyl 2,5-furandicarboxylate.

[0218] Example

[0219] Unless otherwise expressly specified, all ingredients can be obtained from Sigma-Aldrich Chemical Company, St. Louis, Missouri.

[0220] 2,5-furan dicarboxylic acid (FDCA) and dimethyl 2,5-furan dicarboxylate (FDME) were obtained from Sarchem Laboratories Inc, Farmingdale, NJ.

[0221] 1,3-propanediol (BioPDO TM ) was obtained from DuPont Tate & Lyle LLC. For this ingredient, the abbreviation “PDO” is used throughout the examples.

[0222] Titanium isopropoxide (IV) TPT) and tetra-n-butyl titanate TBT) were obtained from Aldrich.

[0223] Butyl tin trichloride 9100) was obtained from PMC Organometallix. REACTHEAT BLUE-2 (titanium nitride dispersion) was obtained from ColorMatrix, Berea, OH.

[0224] All materials were used as received, unless otherwise noted.

[0225] As used herein, “Comp. Ex.” means comparative example; “Ex.” means example.

[0226] Test Methods

[0227] Color Measurement

[0228] The color of the crystallized PTF polymers was measured using a Hunterlab COLORQUEST TM Spectrocolorimeter (Reston, Virginia). Color data were obtained with illuminant D65 at an observer angle of 10 degrees. Color was measured according to the tristimulus color scale, CIE L*a*b*: the color value (L*) corresponds to the lightness or darkness of the sample, the color value (a*) is with respect to the red-green scale, and the color value (b*) is with respect to the yellow-blue scale. Typically, the reported color values are for polymers crystallized overnight in an oven under vacuum at 115-125 °C. The whiteness index (WI) is the calculated value from the equation WI = L*-3b.

[0229] Thermal Analysis

[0230] The glass transition temperature (T) of the crystalline polymers was determined by differential scanning calorimetry (DSC) according to ASTM D3418-08. g )、Melting point (T m ) and enthalpy (ΔH m ). DSC thermograms were recorded using a DSC Q2000 from TA Instruments. 3 to 4 mg of PTF sample was heated from 0°C to 230°C at a heating rate of 10°C / min in a heating-cooling-reheating temperature profile, with a hold time of 3 minutes at 220°C. As reported in the literature reference, Polymer [Polymer] 62, 28, 2015, by using the heat of fusion and by taking a ΔH° of 141.7 J / g. m The crystallinity percentage was calculated from the values.

[0231] Isothermal crystallization

[0232] A sample of approximately 2 to 3 mg of PTF was heated from room temperature to 230°C at a heating rate of 30°C / min, held for 3 minutes, and then cooled to 0°C at 30°C / min to obtain amorphous PTF (quenched in the DSC instrument). The quenched sample was then rapidly heated to a crystallization temperature of 110°C to 120°C and held there for 2-4 hours. A single heating experiment was then applied to the crystallized sample to examine the degree of crystallinity.

[0233] Molecular weight based on size exclusion chromatography

[0234] Size exclusion chromatography (SEC) system, Alliance 2695 TM (Waters Corporation, Milford, MA), equipped with a Waters 2414 TM Differential refractive index detector, multi-angle light scattering photometer DAWN Heleos (Wyatt Technologies, Santa Barbara, CA) and VISCOSTAR II TM The differential capillary viscometer detector was from Wyatt Corporation. The software used for data acquisition and simplification was from Wyatt Corporation. Version 6.1. The column used has an exclusion limit of 2×10 7 Two Shodex GPC HFIP-806M with 8,000 / 30cm theoretical plates TM Styrene-divinylbenzene column; and exclusion limit of 2×10 5and a Shodex GPC HFIP-804M with a theoretical plate count of 10,000 / 30 cm TM styrene-divinylbenzene column.

[0235] The sample was dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) containing 0.01 M sodium trifluoroacetate by mixing at room temperature with moderate agitation for four hours, followed by filtration through a 0.45 μm PTFE filter. The solution concentration was approximately 2 mg / mL.

[0236] Data were obtained with the chromatograph set at 35°C with a flow rate of 0.5 mL / min. The injection volume was 100 μL. The run time was 80 min. Data reduction was performed by combining data from all three detectors described above. Eight scattering angles were used with the light scattering detector. No standards for column calibration were involved in the data processing. Weight average molecular weights (M w ) of the polymers were reported.

[0237] Molecular weights in terms of intrinsic viscosity

[0238] Goodyear R-103B equivalent IV method using PET T-3, DUPONT TM PT-X250, DUPONT TM 2864 as calibration standards, and Intrinsic viscosity (IV) was determined on a forced flow viscometer model Y-501C. Methylene chloride was the carrier solvent and a 50 / 50 methylene chloride / trifluoroacetic acid mixture was the polymer solvent. Samples were prepared at 0.4% (w / v) and shaken overnight at room temperature.

[0239] Number average molecular weight (M 1 ) and end group quantification by n H (proton) NMR

[0240] Approximately 55 mg of sample in 0.7 mL of 1,1,2,2-tetrachloroethane-d2 (tce-d2) was collected on a 700 MHz NMR at 110°C using a 4.68 sec acquisition time, 90 degree pulse, and 30 sec recycle delay, and 16 transients averaged. 1 H NMR spectrum.

[0241] 1 H NMR calculation method

[0242] The sample was integrated and the mole percent was calculated as is standard in the art. The peak assignments for the PTF polymers are shown in Table 1 below.

[0243] Table 1

[0244]

[0245]

[0246] According to 1 Method for determining the total amount of cyclic ester in poly(trimethylene-2,5- furandicarboxylate) by H NMR

[0247] As shown in Table 1, the hydrogen on the furan ring of the cyclic dimer (δ 6.89) and the hydrogen on the furan ring of the PTF polymer (δ 7.2) have different chemical shifts. The weight percent of the cyclic dimer was calculated using the following equation:

[0248]

[0249]

[0250] nI = normalized integral value

[0251] Comparative Example A

[0252] Synthesis of poly(trimethylene-2,5-furandicarboxylate) (PTF)

[0253] The transesterification temperature used in this comparative example was 185°C - 245°C.

[0254] Dimethyl-2,5-furandicarboxylate (27 kg), 1,3-propanediol (20.08 kg), and titanium (IV) tetrabutoxide (40.8 g) were charged into a 15 gallon stainless steel autoclave equipped with an agitator, oil heated jacket, and condenser on an exhaust line. A nitrogen purge was applied and agitation was started at 50 rpm to form a slurry. While agitating, the autoclave was subjected to three cycles of pressurization with 50 psi of nitrogen followed by a pressure leak check at 60 psi. A weak nitrogen purge was then established to maintain an inert atmosphere. While heating the autoclave to a set point of 240°C, methanol evolution began at a batch temperature of 175°C. The methanol distillation was continued for 180 minutes during which the batch temperature increased from 185°C to 245°C. At this point, a vacuum ramp was started which reduced the pressure from 760 torr (101.3 kPa) to 110 torr (14.66 kPa) over a 30 minute period (pumped through the column), and from 110 torr to 0.7 torr over the next 2 hours (pumped through a separate exhaust line to a vacuum pump). While at 0.7 torr, the mixture was left under vacuum and agitated for 2 hours. During this time, the agitator speed was gradually reduced from 50 rpm to 20 rpm, after which the vessel was pressurized back to 760 torr using nitrogen.

[0255] The PTF polymer was recovered by pressurizing the autoclave to 50 psi and pushing the melt through an outlet valve at the bottom of the vessel into a melt gear pump, die orifice, and water quench bath to form strands. The strands were banded through a granulator equipped with air jets to dry the polymer without moisture, and the polymer strands were cut into pieces that were about 3 mm long and about 2 mm in diameter.

[0256] The granulated polymer was initially crystallized by placing the material in a vacuum rotary drum dryer, followed by heating the granules to 110 °C under vacuum for 6 hours. The polymer was characterized by proton NMR, DSC, intrinsic viscosity, SEC, and spectrophotometer and the results are reported in Tables 2 and 3.

[0257] Comparative Example B

[0258] Solid State Polymerization of the PTF Polymer of Comparative Example A

[0259] The granulated and crystallized PTF polymer was prepared as described in Comparative Example A. The crystallized polymer was heated in a rotary drum dryer at a temperature of 165 °C, and the granules were under nitrogen purge conditions for 154 hours to build high molecular weight. The oven was turned off and the granules were allowed to cool. The solid state polymerized polymer was analyzed and the results are reported in Tables 2 and 3.

[0260] Table 2

[0261]

[0262] ND = not determined

[0263] Table 3

[0264]

[0265] ND = not determined

[0266] Comparative Examples A and B illustrate problems associated with forming poly(trimethylene furandicarboxylate) using typical polycondensation techniques followed by solid state polymerization with poly(ethylene terephthalate), namely (i) very long solid state polymerization times (> 150 hours) to build the desired high molecular weight PTF polymer; (ii) low melting temperature of the crystallized polymer melt product; (iii) high levels of di-PDO in the polymer backbone and at the chain ends that can alter the properties and stability of the polymer; (iv) low L* and high b* color values of the resin; (v) the as-prepared melt polymer is amorphous, has no melting temperature during thermal cycling, and the melt has no crystallization peak upon cooling; (vi) the crystallized polymer has very slow thermal crystallization rates, as indicated by the half cold crystallization time; and (vii) significant reduction in the melting temperature of the solid state polymer after isothermal crystallization due to low crystallinity in the polymer backbone and high levels of di-PDO.

[0267] Comparative Example C

[0268] Comparative Example C differs from Comparative Example A in batch size and transesterification temperature.

[0269] Dimethyl 2,5-furandicarboxylate (60 g, 0.32 mol), BioPDO TM (1,3-propanediol, 44.6 g, 0.59 mol) and titanium (IV) isopropoxide (200 ppm titanium based on weight of polymer) were charged into a pre-dried 250 mL three necked round bottom glass reactor fitted with an overhead stirrer equipped with a SS 304 half moon stir bar, a distillation condenser and a nitrogen inlet / outlet. A nitrogen blanket was applied to the flask, which was maintained at a temperature of 23 °C. Stirring was initiated at 50 rpm to form a slurry. While stirring, the flask was evacuated to 0.13 MPa and then pressurized with N2, for a total of three cycles.

[0270] After the three cycles of evacuation and pressurization, the flask was immersed into a preheated liquid metal bath set at 190 °C. After the contents of the flask were placed into the liquid metal bath while being sparged with N2 gas at a slow rate, it was stirred for 10 min, allowing the solid ingredients to melt. The actual temperature of the reaction medium was slightly lower than the metal bath set temperature by 5 °C to 10 °C. Next, the stirring speed was increased to 180 rpm. The flask was initially maintained at 190 °C for one hour and then the set temperature was increased to 210 °C for an additional 1.5 hours while stirring at 180 rpm to distill off most of the methanol formed in the reaction. After this transesterification step, the set temperature of the metal bath was increased to 250 °C while the pressure of the reactor was slowly decreased from about atmospheric to about 900 mTorr for a period of 45 minutes. The major portion of the excess PDO present in the reactor was removed when the reaction mixture was at 250 °C. The condensation reaction continued at 250 °C for 3 hours while removing the reaction byproducts when the vacuum was at a maximum (typically 150-250 mTorr).

[0271] After cooling to room temperature, the produced polymer was recovered from the flask. The recovered polymer was pelletized using a Wiley mill cooled with liquid nitrogen. The polymer pellets were dried in an oven under vacuum and a weak nitrogen stream at 110 °C overnight to crystallize the pellets. The method conditions and properties of the crystallized polymer are reported in Table 4.

[0272] Comparative Example D

[0273] A PTF polymer was prepared as described in Comparative Example C, except that dimethyl 2,5-furandicarboxylate was replaced with 2,5-furandicarboxylic acid. The method conditions and properties of the polymer are reported in Table 4.

[0274] Table 4

[0275]

[0276]

[0277] NA = Not Applicable

[0278] These comparative examples show that the polymers obtained under the described melt conditions have di-PDO levels greater than 1 wt% in the polymer backbone and are significantly discolored as seen by their visual appearance, which is undesirable for most commercial uses. In the case of Comparative Example D, the b* value appears to be lower than that of Comparative Example C, which can be due to the masking effect of black color (very low L* value) on yellowness.

[0279] Example 1

[0280] A pre-polymer was first prepared as described below: Dimethyl 2,5-furandicarboxylate (60 g, 0.326 mol) and 1,3-propanediol (37.2 g, 0.489 mol) were charged into a pre-dried 250 mL three-necked round bottom glass reactor fitted with an overhead stirrer equipped with a SS 304 half-moon stir bar, a distillation condenser, and a nitrogen inlet / outlet in a 1.5 mole ratio of 1,3-propanediol to dimethyl 2,5-furandicarboxylate. Titanium tetrabutylate was diluted by adding 0.23 mL to 10 mL of 1,3-propanediol and 1 mL of this solution (50 ppm of titanium based on the weight of the polymer) was added to the flask. A nitrogen blanket was applied to the flask, which was maintained at a temperature of 23 °C. Stirring was started at 50 rpm to form a slurry. While stirring, the flask was evacuated to 0.13 MPa and then pressurized with N2, for a total of three cycles.

[0281] After the three cycles of evacuation and pressurization, the flask was immersed in a preheated liquid metal bath set at 190 °C. After placing the contents of the flask in the liquid metal bath while sparging it with N2 gas at a slow rate, it was stirred for 10 minutes, allowing the solid ingredients to melt. The actual temperature of the reaction medium was slightly lower than the metal bath set temperature by 5 °C to 10 °C. Next, the stirring speed was increased to 180 rpm. The ester exchange reaction was carried out at a set temperature of 190 °C for 1 hour and for an additional hour at 10 °C while distilling off most of the methanol (24.5 mL) formed in the reaction. After 2 hours, the pressure was reduced by slowly applying vacuum to 2.5 torr (0.33 kPa) for a period of 45 min. After 45 minutes, full vacuum (150-220 mtorr) was applied for 90 minutes to remove excess PDO from the reaction. The reaction temperature was maintained not to exceed 210 °C, and this step is referred to as the pre-polycondensation step.

[0282] The reaction mixture was cooled to room temperature while the pressure was allowed to reach atmospheric. A small sample of prepolymer was collected for analysis and the remaining material was reheated to melt and the polycondensation reaction was carried out under full vacuum at a bath set temperature of 250 °C for 3 hours. The polymer was recovered and crystallized in a vacuum oven at 120 °C overnight. The properties of the prepolymer and final polymer are reported in Table 5.

[0283] Example 2

[0284] Example 2 was scaled up from 250 mL (Example 1) to a 3 L reactor. The following amounts of ingredients were charged to a 3 L, three neck, glass reactor: dimethyl 2,5-furandicarboxylate (1.126 kg; 6.12 mol), 1,3-propanediol (0.698 kg, 9.176 mol), and tetra-n-butyl titanate (0.43 g; 50 ppm titanium based on the weight of the polymer). The molar ratio of PDO to FDME was 1.5. The flask was placed in a metal bath preheated to 160 °C. The reaction mixture was stirred at 100 rpm under a nitrogen atmosphere for 10 minutes to obtain a homogeneous solution and then the metal bath temperature was increased to 190 °C to initiate the transesterification reaction. The reaction was continued at this temperature for 2 h, the temperature was increased to 210 °C and the reaction was continued for an additional 30 min. The vacuum ramp was initiated while the nitrogen purge was discontinued. The pressure was gradually decreased from atmospheric to a final low pressure of 0.1 to 1.0 mm Hg absolute. Full vacuum and a temperature of 190 °C were maintained for 60 min while the excess PDO was removed. The solid prepolymer was recovered from the flask.

[0285] A small portion of the prepolymer (60 g) was charged to a 250 mL, three neck, flask and the flask was placed in a metal bath preheated to 190 °C. When full vacuum was achieved, the temperature of the metal bath was increased to 240 °C and the polycondensation reaction was continued under these conditions for 4 hours. The polymer after melt polymerization was recovered, crystallized and analyzed. The properties of the prepolymer and final polymer are reported in Table 5.

[0286] Example 3

[0287] The ester interchange reaction and prepolymerization steps were carried out at lower temperatures as described below. The following amounts of ingredients were charged into a 3 L three necked glass reactor: dimethyl 2,5-furandicarboxylate (1.408 kg; 7.64 mol) and 1,3-propanediol (0.873 kg; 11.47 mol). The molar ratio of PDO to FDME was 1.5. The flask was placed in a metal bath preheated to 160 °C. The reaction mixture was stirred at 100 rpm for 10 minutes under a nitrogen atmosphere to obtain a homogeneous solution. The catalyst tetra-n-butyl titanate (1.097 g; 110 ppm of titanium based on the weight of the polymer) was added at this temperature. The metal bath temperature was raised to 170 °C to initiate the ester interchange reaction. The reaction was continued at this temperature for 100 minutes, the temperature was raised to 180 °C and the reaction was continued for 40 min. The temperature was raised again to 190 °C and the reaction was continued for another 40 min. The vacuum ramp was started while the nitrogen purge was stopped. The pressure was gradually reduced from atmospheric pressure to a final low pressure of 0.1 to 1.0 mm Hg absolute. The full vacuum and the temperature of 190 °C were maintained for 60 min while the excess PDO was removed. The solid prepolymer was recovered from the flask.

[0288] A small portion of the prepolymer (60 g) was charged into a 250 mL three necked flask and the flask was placed in a metal bath preheated to 190 °C. When full vacuum was reached, the temperature of the metal bath was raised to 240 °C and the polycondensation reaction was continued at these conditions for 4 hours. The polymer after melt polymerization was recovered, crystallized and analyzed. The properties of the prepolymer and the final polymer are reported in Table 5.

[0289] Table 5

[0290]

[0291]

[0292] The prepolymers prepared as described in Examples 1-3 surprisingly had very low levels of di-PDO. Reducing the temperature during transesterification and precondensation had a significant impact on reducing ether formation. Controlling the temperature during transesterification and precondensation without the addition of any additives allowed the amount of di-PDO to be managed. Although the transesterification conditions were not optimized in the 3L, it was highly feasible to reduce the level of methyl ester in the prepolymer. The PTF melt polymers of Examples 1-3 had very low levels of di-PDO in the polymer backbone (as low as 0.17 wt%) and were not detectable at the chain end compared to Comparative Example A (3.4 wt%). It appears from the data that ether formation occurs more in the transesterification / precondensation step than in the condensation step. The higher temperature during condensation had little impact on di-PDO formation, which can be due to the absence of excess PDO limiting side reactions. In addition, the polymers of Examples 1-3 had lower carboxylic acid and allyl ends, indicating less polymer degradation and side reactions, resulting in polymers with higher stability and improved color. These three examples of the present invention show that using the disclosed process conditions and titanium catalyst loading, high molecular weight PTF polymers with superior properties can be produced in a melt polymerization process and thus eliminate the expensive and time consuming solid state polymerization step.

[0293] Examples 4 and 5

[0294] The polymers of Examples 4 and 5 were prepared as described for Example 1 with the following exceptions: the catalyst system was different as shown in Table 6 and the polymers were prepared in one stage (without cooling after precondensation). In Example 4, a mixture of FDA (Food & Drug Administration) grade butyl tin tracetate (REACTHEAT BLUE-1®) and tetra-n-butyl titanate (REACTHEAT BLUE-2®) catalyst system (80 ppm tin / 20 ppm titanium) was used. In Example 5, a mixture of butyl tin tracetate and titanium nitride (REACTHEAT BLUE-2) (90 ppm tin / 10 ppm titanium) was used. 9100) and tetra-n-butyl titanate (REACTHEAT BLUE-2®) catalyst system (80 ppm tin / 20 ppm titanium) was used. In Example 5, a mixture of butyl tin tracetate and titanium nitride (REACTHEAT BLUE-2) (90 ppm tin / 10 ppm titanium) was used.

[0295] The polymers after melt polymerization were crystallized and analyzed. The methods and properties of the polymers are reported in Table 6.

[0296] Table 6

[0297]

[0298]

[0299] ​The properties of each of the PTF polymers of Examples 2-5 were analyzed by DSC before and after measuring their isothermal semi-crystallization times. This data was compared to the data for the solid state PTF polymer of Comparative Example B in Tables 7 and 8.

[0300] Table 7

[0301]

[0302] When the crystallized PTF polymers of Example 2, Example 4, and Example 5 were heated at 1 °C / min instead of 10 °C / min, a different cold crystallization temperature (T cc ) peak of about 119-128 °C was observed. In addition, the melting temperature of the polymers was almost 10 °C higher when the polymers were crystallized at the slower heating rate, indicating a more uniform crystal morphology. This higher melting temperature of the polymers can be beneficial in improving the solid state polymerization rate, making it faster.

[0303] Table 8

[0304]

[0305] Isothermal crystallization temperature was 118 °C

[0306] The data in Table 8 indicates that the PTF polymers of Examples 2-5 have significantly lower semi-crystallization times (faster crystallization kinetics), higher glass transition temperatures, and higher melting temperatures than the solid state polymerized polymer of Comparative Example B. The lower di-PDO level in the polymer backbone helps the polymer to crystallize at a faster rate. The estimated percent crystallinity of the PTF polymers of Examples 2-5 was in the range of 29-30%.

[0307] Comparative Example E

[0308] An attempt was made to make a prepolymer by charging a 3 L, three necked glass reactor with the following: dimethyl 2,5-furandicarboxylate (1.300 kg; 7.06 mol), 1,4-butanediol (0.955 kg; 10.6 mol), and tetra-n-butyl titanate (0.21 g; 50 ppm of titanium based on the weight of the polymer). The molar ratio of 1,4-butanediol to FDME was 1.5. The flask was placed in a metal bath preheated to 160 °C. The reaction mixture was stirred at 100 rpm for 10 minutes under a nitrogen atmosphere to obtain a homogeneous solution. The metal bath temperature was raised to 180 °C and the transesterification reaction was continued at this temperature for 40 minutes, the temperature was raised to 200 °C and the reaction was continued for another 40 min. During this period, 600 mL of distillate was collected, which was greater than the theoretical amount of methanol (571 mL). While the distillate was still continuing, vacuum was applied to remove excess 1,4-butanediol. However, due to the production of low volatility gaseous product tetrahydrofuran (THF), we were unable to reduce the vacuum and thus terminated the prepolymerization process. When the distillate was analyzed, we found that the distillate contained a significant amount of THF (11.4 wt%) along with 83.8 wt% of methanol, and 3.5 wt% of 1,4-butanediol. This comparative example shows that the transesterification and prepolymerization process conditions employed are unique to 1,3-propanediol based PTF polymers and cannot be implemented for 1,4-butanediol based poly(2,5-furandicarboxylic acid butylene ester) polymers.

Claims

1. A composition comprising: A poly(trimethylene furandicarboxylate) polymer comprising: ix) 95% to 99.9% by weight of trimethylene furandicarboxylate repeating units; x) less than or equal to 1% by weight of di-PDO repeating units in the polymer backbone; xi) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer; xii) less than or equal to 15 milliequivalents of carboxylic acid end groups per kilogram of polymer; xiii) less than or equal to 10 milliequivalents of alkyl ester end groups per kilogram of polymer; xiv) less than or equal to 1% by weight of cyclic dimer oligoesters; xv) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; as well as xvi) an intrinsic viscosity within the range of from 0.70 to 1.2 dL / g; wherein the weight percentages are based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition, The poly(trimethylene furandicarboxylate) polymer has a crystallization half time less than or equal to 100 minutes, measured at 120°C, and The poly(trimethylene furandicarboxylate) polymer is obtained by a method comprising: a) contacting a mixture comprising a dialkyl furandicarboxylate, 1,3-propylene glycol, and a metal catalyst at a temperature in the range of from 160° C. to 220° C. to form a prepolymer, wherein the molar ratio of the dialkyl furandicarboxylate to the 1,3-propylene glycol is in the range of from 1:1.3 to 1:2.2, and the concentration of the metal catalyst is in the range of from 20 ppm to 400 ppm based on the total weight of the mixture; b) removing at least a portion of the unreacted 1,3-propanediol at a temperature in the range of from 180° C. to 220° C.; as well as c) heating the prepolymer under reduced pressure to a temperature in the range of from 230° C. to 260° C. to form the poly(trimethylene furandicarboxylate) polymer while removing 1,3-propylene glycol, In this case, at least 90% by weight of the excess 1,3-propanediol is removed in step b).

2. The composition according to claim 1, wherein The composition has a b* color value of less than 15 as determined by spectrocolorimetry.

3. The composition according to claim 1, wherein The composition has a b* color value of less than 10 as determined by spectrocolorimetry.

4. The composition according to claim 1, wherein The composition has an L* color value greater than or equal to 60 as determined by spectrocolorimetry.

5. The composition of claim 1 , further comprising one or more additives including a thermal stabilizer, a UV absorber, an antioxidant, a nucleating agent, a processing aid, a toner / optical brightener, an oxygen barrier additive, a chain extender, a chain terminator, a reheat agent, or a light blocker.

6. The composition according to claim 1, wherein The dialkyl furandicarboxylate is dimethyl 2,5-furandicarboxylate.

7. A composition comprising: A poly(trimethylene furandicarboxylate) polymer comprising: ix) 95% to 99.9% by weight of trimethylene furandicarboxylate repeating units; x) less than or equal to 1% by weight of di-PDO repeating units in the polymer backbone; xi) less than or equal to 20 milliequivalents of allyl end groups per kilogram of polymer; xii) less than or equal to 21 milliequivalents of carboxylic acid end groups per kilogram of polymer; xiii) less than or equal to 15 milliequivalents of alkyl ester end groups per kilogram of polymer; xiv) less than or equal to 1% by weight of cyclic dimer oligoesters; xv) less than or equal to 10 milliequivalents of di-PDO end groups per kilogram of polymer; as well as xvi) an intrinsic viscosity within the range of from 0.60 to 1.2 dL / g; wherein the weight percentages are based on the total weight of the poly(trimethylene furandicarboxylate) polymer in the composition, The poly(trimethylene furandicarboxylate) polymer has a crystallization half time less than or equal to 100 minutes, measured at 120°C, and The poly(trimethylene furandicarboxylate) polymer is obtained by a method comprising: a) contacting a mixture comprising a dialkyl furandicarboxylate, 1,3-propylene glycol, and a metal catalyst at a temperature in the range of from 160° C. to 220° C. to form a prepolymer, wherein the molar ratio of the dialkyl furandicarboxylate to the 1,3-propylene glycol is in the range of from 1:1.3 to 1:2.2, and the concentration of the metal catalyst is in the range of from 20 ppm to 400 ppm based on the total weight of the mixture; b) removing at least a portion of the unreacted 1,3-propanediol at a temperature in the range of from 180° C. to 220° C.; as well as c) heating the prepolymer under reduced pressure to a temperature in the range of from 230° C. to 260° C. to form the poly(trimethylene furandicarboxylate) polymer while removing 1,3-propylene glycol, In this case, at least 90% by weight of the excess 1,3-propanediol is removed in step b).

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