Method for manufacturing polyester containing recycled materials

Abstract

The present invention relates to a method for manufacturing polyester having various aspects of recycled materials. The method of the present invention effectively and cost-effectively incorporates recycled DMT into an existing TPA-based polyester manufacturing system. The present invention also relates to a recycled feed composition for manufacturing polyester having recycled materials and recycled polyester.

Description

Technology Field

[0001] The present invention relates to a polyester manufacturing process comprising the use of a methanolysis reaction product in forming a polyester having a recycle content, in general, in the field of polyester recycling and polyester manufacturing, more particularly in forming a polyester having a recycle content. Background Technology

[0002] Polyester is one of the most widely purchased and utilized classes of polymers in the world, and recent reports indicate that disclosed global production (including recycling) far exceeds 75 million tons. This level of commercial success is likely partly attributed to the attractive combination of polyester's relative cost, manufacturability, and competitive performance attributes. Due to its physical, chemical, and thermal properties, polyester is useful and desirable for a wide range of end-use applications. Polyethylene terephthalate (PET) is one of the most popular types of polyester for many end-uses. In general, as polyester and especially PET have achieved commercial success, efforts have been made to recover materials from after-consumption, after-industrial use, scrap, and other sources, and to reuse these materials as an alternative to primary disposal methods such as landfilling.

[0003] In one known recycling method, recycled PET is blended with virgin material. This approach has been used, for example, to produce PBT-based products with a recycle content by preparing a blend of virgin poly(butylene terephthalate) ("PBT") with recycled PET (see, for example, U.S. Patent Application No. 2009 / 0275698). However, such blends generally do not mix well and can produce relatively opaque materials. Therefore, blending is not a uniformly satisfactory method for providing recycle to a commercially valuable end product.

[0004] In other recycling methods, polyester is depolymerized to form the monomer units originally used in its manufacture. One commercially used method for polyester depolymerization is kameethanol cracking. In kameethanol cracking, polyester reacts with methanol to produce a depolymerized polyester mixture comprising polyester oligomers, dimethyl terephthalate ("DMT"), and ethylene glycol ("EG"). For example, other monomers such as 1,4-cyclohexanedimethanol ("CHDM") and diethylene glycol may also be produced depending on the composition of the polyester in the kameethanol cracking feed stream. Some representative methods for the kameethanol cracking of PET are U.S. Patents No. 3,037,050; No. 3,321,510; No. 3,776,945; No. 5,051,528; and No. 5,298,530. Described in Patents No. 5,414,022; No. 5,432,203; No. 5,576,456 and No. 6,262,294, the contents and disclosures thereof are incorporated herein by reference. Representative methods for ga-methanol cracking are also described in U.S. Patent No. 5,298,530, the contents and disclosures thereof are incorporated herein by reference. The '530 patent describes a method for recovering ethylene glycol and dimethyl terephthalate from scrap polyester. The method comprises the steps of dissolving scrap polyester in an oligomer of ethylene glycol (EG) and terephthalic acid (TPA) or dimethyl terephthalate (DMT), and passing superheated methanol through the mixture. The oligomer may comprise any low molecular weight polyester polymer having the same composition as the scrap material used as a starting component so that the scrap polymer dissolves in the low molecular weight oligomer. Dimethyl terephthalate and ethylene glycol are recovered from the methanol vapor stream coming out of the depolymerization reactor.

[0005] The uses of monomer units produced by depolymerization, particularly DMT and EG, are continuously being investigated by manufacturers with the aim of producing and selling new materials containing recycled materials. For example, the assignee of this disclosure proposes in U.S. Patent Application No. 2013 / 0041053 that recycled monomers, such as DMT, can generally be combined with unused monomers in polyester manufacturing. However, this proposal has drawbacks. First, consider the operation of the esterification / ester exchange step at a temperature, generally about 150 to about 250°C, for about 0.5 to about 8 hours, and at a pressure of about 0.0 to about 414 kPa gauge (pounds per square inch, psig). These conditions do not match the operating conditions suitable for current terephthalic anhydride-based (TPA-based) polyester manufacturing processes, in which the feed substantially does not contain intentionally added esters but only diacids, mainly terephthalic acid, and one or more glycols. Therefore, obtaining recycled materials by incorporating recycled materials, such as recycled DMT (r-DMT) and / or recycled ethylene glycol (r-EG), into current TPA-based processes would not be feasible without process setup and manipulation of related product uniformity and yield, and possible interruptions. Additionally, Publication '503 states that when using mixed acid / ester feedstocks, the three-step manufacturing process described in U.S. Patent No. 5,290,631 must be used. The additional process step entails additional capital, manufacturing, and labor costs.

[0006] Therefore, there continues to be an unmet need for a method to produce polyesters with recycled materials by effectively and cost-effectively incorporating recycled materials, such as recycled DMT (r-DMT) and recycled ethylene glycol (r-EG), into existing TPA-based polyester manufacturing systems.

[0007] In a first aspect, the present disclosure comprises the steps of: supplying a recycled feed comprising an ester recycled material selected from the group consisting of r-DMT, ester-exchanged r-DMT and combinations thereof to one or more reaction zones to form a reaction mixture comprising the recycled material in said one or more reaction zones; reacting said reaction mixture to form a polyester oligomer mixture having the recycled material; and polycondensing the recycled material oligomer mixture to form a polyester having the recycled material.

[0008] In another aspect, the present disclosure relates to a recycled feed composition for the production of a polyester having recycled materials. The recycled feed composition of the present disclosure comprises an ester recycled material selected from the group consisting of r-DMT, ester-exchanged r-DMT and combinations thereof; and one or more of a dimethyl isophthalate recycled material (r-DMI) and a residual catalyst material selected from the group consisting of germanium materials, antimony materials and combinations thereof.

[0009] In another aspect, the present disclosure relates to a polyester having recycled materials.

[0010] Additional aspects of the present disclosure are as disclosed and claimed herein. Specific details for implementing the invention

[0011] As used herein, the term “polyester” generally means including, but not limited to, homopolyesters, as well as copolyesters, terpolyesters, etc., and is typically prepared in the general sense by reacting a difunctional acid, its ester, or a mixture of such acid or ester with a difunctional hydroxyl compound, often a diol or glycol, or a mixture of such diol or glycol. Alternatively, the difunctional carboxylic acid may be a hydroxycarboxylic acid, and the difunctional hydroxyl compound may be an aromatic nucleus having two hydroxyl substituents, e.g., hydroquinone. Of particular interest in connection with the present disclosure as described herein is a polyester produced by depolymerization by gametholactic hydrolysis or glycolysis by gametholactic hydrolysis of the subsequent reaction product, which produces one or both of dimethyl terephthalate and ethylene glycol through gametholactic hydrolysis.

[0012] In a first aspect, the present disclosure relates to a method for producing a polyester having a recycled material. The method of the present disclosure comprises the steps of: supplying a recycled feed comprising an ester recycled material selected from the group consisting of r-DMT, ester-exchanged r-DMT, and combinations thereof to one or more reaction zones to form a reaction mixture having a recycled material in said one or more reaction zones; reacting said reaction mixture to form a polyester oligomer mixture having a recycled material; and polycondensing the recycled material oligomer mixture to form a polyester having a recycled material.

[0013] In one or more embodiments, the reaction step comprises reacting the reaction mixture at a temperature of 250°C or higher for a total average residence time of 30 minutes to 12 hours or 1 to 10 hours or 1 to 8 hours. In one or more embodiments, the reaction step comprises reacting the reaction mixture at a temperature of 250 to 350°C or 250 to 300°C or 260 to 300°C or 250 to 275°C.

[0014] As mentioned above, polyesters can be prepared in the general sense by reacting a diacid, its ester, or a mixture of such an acid or ester with a difunctional hydroxyl compound, often a diol or glycol, or a mixture of such a diol or glycol. Accordingly, those skilled in the art will understand that, in order to form a polyester having the recycled material of this disclosure, a reaction mixture of one or more reaction zones comprises components known in the art for forming polyesters, for example, (i) a diacid, its ester, or a mixture of such an acid or ester, and (ii) a difunctional hydroxyl compound such as a diol or glycol, or a mixture of such a diol or glycol. In one or more embodiments, the reaction mixture comprises a recycled component. In one or more embodiments, the reaction mixture comprises a recycled component and an unused component. As used herein, the term “recycled” is intended to mean that, for example, scrap, off-spec material, waste, post-consumption or post-industrial use material is supplied through recycling. As used herein, the term “unused” is intended to mean manufactured from raw materials, such as fossil fuel-based or bio-based materials, as opposed to being supplied through the recycling of, for example, scrap, substandard materials, waste, or materials after consumption or industrial use.

[0015] In one or more embodiments, the feeding step of the method of the present disclosure further comprises the step of feeding a diol recycling material selected from the group consisting of r-EG, recycled diethylene glycol (r-DEG) and combinations thereof to one or more reaction zones.

[0016] In one or more embodiments, the recycled feed further comprises a dimethyl isophthalate recycled material (r-DMI). In one or more embodiments, r-DMI is present in the recycled feed in an amount of 2,000 ppm or more, 1,500 ppm or more, 1,000 ppm or more, or 500 ppm or more. In one or more embodiments, the recycled feed may further comprise a terephthalic acid recycled material (r-TPA), which may comprise r-TPA formed through the hydrolysis of r-DMT. In one or more embodiments, the method of the present invention may comprise a step of hydrolyzing at least some r-DMT to form r-TPA prior to a reaction step.

[0017] In one or more embodiments, the recycled feed further comprises a residual catalytic material. The residual catalytic material may be one or more materials or compounds present in the recycled feed, the source of which is the original polyester depolymerized to form r-DMT. In one or more embodiments, the residual catalytic material may be selected from the group consisting of germanium materials, antimony materials, and combinations thereof. In one or more embodiments, the antimony material is present in the recycled feed in an amount of 5 to 500 ppm, 10 to 500 ppm, 20 to 500 ppm, or 5 ppm or more. In one or more embodiments, the germanium material is present in the recycled feed in an amount of 5 to 500 ppm, 10 to 500 ppm, 20 to 500 ppm, or 5 ppm or more.

[0018] In one or more embodiments, the recycled feed further comprises a dimethyl isophthalate recycled material (r-DMI) and a residual catalyst material selected from the group consisting of germanium material, antimony material and combinations thereof.

[0019] In one or more embodiments, the feeding step of the method of the present disclosure further comprises the step of feeding an unused feed to one or more reaction zones. In one or more embodiments, one or more diols of the unused feed feed feed unused diols. The unused feed may comprise one or more other unused materials, such as, for example, unused diacid, unused diester, unused branching agent, for example, trimellitic anhydride.

[0020] In one or more embodiments, the unused feed substantially does not contain an unused diester component. In one or more embodiments, the unused feed substantially does not contain an unused discate component. Accordingly, in one or more embodiments, the reaction mixture may contain an unused diol component, may not substantially contain an unused discate component, or may not substantially contain an unused diester component. As used herein, the phrase “substantially not” is generally intended to mean that the unused feed does not contain any intentionally added unused acid and / or ester content. However, those skilled in the art will understand that an accidental discate / diol reaction in the unused feed may form trace amounts of unused diester compounds. Accordingly, in one or more embodiments, when describing the unused diester content of the unused feed, the phrase “substantially not containing” is intended to mean that the unused feed contains 5 mol% or less, 4 mol% or less, 3 mol% or less, 2 mol% or less, or 1 mol% or less of unused diester compounds based on the total sum of discrete moles + diester moles in the unused feed. In one or more embodiments, the reaction mixture may contain 95 weight% or more, 96 weight% or more, 97 weight% or more, 98 weight% or more, 99 weight% or more, or 100 weight% of recycled feed based on the total weight of the reaction mixture.

[0021] In one or more embodiments of these aspects, the step of supplying unused feed to a reaction zone precedes the step of supplying recycled feed. In one or more embodiments of these aspects, the method further comprises the step of reacting at least a portion of the unused feed in a reaction zone to form an unused polyester oligomer before or simultaneously with the step of supplying recycled feed.

[0022] In one or more embodiments, the ester recycled material in the feed step is added in an amount sufficient to account for 1 to 100 mol%, 25 to 100 mol%, 90 to 100 mol%, or 1 to 50 mol% based on the total discrete molar of 1,4-dicarboxybenzene equivalents in the polyester having the recycled material. The relative amounts of r-DMT and the discrete component (if present in the polyester unused feed stream) in the reaction mixture will affect the type, structure, and total recycled material of the specific polyester formed by the method of the present disclosure.

[0023] In one or more embodiments, the step of adding the unused feed to the reaction zone is initiated after the step of feeding the ester recycling material to the reactor. In one or more embodiments, the step of adding the unused feed to the reaction zone and the step of feeding the recycled feed to the reaction zone are initiated simultaneously or at the same physical location. Although the disclosure has generally been described in terms of the step of feeding the recycled feed and, in some embodiments, feeding the unused feed to the reaction zone to form a reaction mixture, it will be acknowledged that the number and content of individual feed streams for the feed material are not necessarily limited. As a non-limiting example, the method may include the step of combining the recycled feed and the unused feed to form a combined recycled / unused feed, and the step of feeding the combined recycled / unused feed to one or more reaction zones to form a reaction mixture.

[0024] In some common TPA-based polyester manufacturing processes, the dominant acid component may be terephthalic acid and may optionally contain an amount of isophthalic acid less than the amount of terephthalic acid. Accordingly, in one or more embodiments, the unused feed comprises an unused diate component. In one or more embodiments, the unused feed comprises one or both of unused terephthalic acid and unused isophthalic acid. In one or more embodiments, the unused diate component of the unused feed comprises 90 mol% or more, 92 mol% or more, 94 mol% or more, 95 mol% or more, 96 mol% or more, or 98 mol% or more of unused terephthalic acid based on the total moles of the diate in the unused feed. In one or more embodiments, the unused feed comprises 10 mol% or less or 5 mol% or less of unused isophthalic acid based on the total moles of acid in the unused feed. In one or more embodiments, the discrete component of the unused feed comprises 100 mol% of terephthalic acid based on the total molar of acid in the unused feed.

[0025] A TPA-based polyester manufacturing process can be used to produce a copolyester having two or more diol residues. Accordingly, in one or more embodiments, the unused feed comprises one or more unused diols. Suitable diols are well known in the art and, as non-limiting examples, include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetrahydrofuran, polyoxymethylene, isosorbide, 1,3- and 1,4-cyclohexanedimethanol (CHDM), 1,4-cyclohexanedimethanol, 2,2,4,4-tetraalkylcyclobutanediol, e.g., 2,2,4,4-tetramethylcyclobutanediol (TMCD), neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerol, trimethylolpropane, It includes pentaeryltritol, resorcinol, hydroquinone, catechol, and isomers and combinations thereof. In one or more embodiments, the unused diol component of the unused feed comprises one or more diols selected from the group consisting of ethylene glycol, diethylene glycol, neopentyl glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), cyclohexanedimethanol (CHDM), and isomers and combinations thereof.

[0026] The ester recycling material in the feed step is selected from the group consisting of recycled dimethyl terephthalate (r-DMT), trans-esterified r-DMT, and combinations thereof. The trans-exchanged r-DMT used herein is intended to replace the methyl ester functional group of r-DMT with an ester functional group formed from one or more alcohols, e.g., r-DMT trans-exchanged with one or more alcohols. Accordingly, in one or more embodiments, the method of the present disclosure comprises, prior to the feed step, a step of pre-reacting at least a portion of r-DMT with one or more alcohols to form trans-esterified r-DMT. In one or more embodiments, the alcohol is ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetrahydrofuran, polyoxymethylene, isosorbide, 1,3- and 1,4-cyclohexanedimethanol (CHDM), 2,2,4,4-tetraalkylcyclobutanediol, e.g., 2,2,4,4-tetramethylcyclobutanediol (TMCD), neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerol, trimethylolpropane, pentaeryltritol, resorcinol, hydroquinone, catechol, and their The alcohol is a diol selected from the group consisting of isomers and combinations. In one or more embodiments, the alcohol is a diol selected from the group consisting of ethylene glycol, diethylene glycol, neopentyl glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, cyclohexanedimethanol, ethylene glycol, 2,2,4,4-tetramethyl-1,4-cyclobutanediol, and isomers and combinations thereof. In one or more embodiments, the pre-reaction step is carried out in the presence of a metal-based catalyst.Non-limiting examples of metals for metal-based catalysts include Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu, and combinations thereof. In one or more embodiments, the metal for the metal-based catalyst is selected from the group consisting of titanium, manganese, zinc, and combinations thereof. In one or more embodiments, the reaction conditions for the pre-reaction step will be selected to replace most of the methyl ester functional groups (greater than 50 mol%) of the recycled material with diol ester linkers from one or more glycols of the pre-reaction step, e.g., 2,2,4,4-tetramethyl-1,4-cyclobutanediol ester linkers. In one or more embodiments, one or more glycols of the pre-reaction step comprise 2,2,4,4-tetramethyl-1,4-cyclobutanediol, and the catalyst is a tin catalyst.

[0027] One measure of a reactant in a reaction mixture is known as the "molar ratio," which is the ratio of the molar amount of the diol in the reaction mixture to the molar amount of the total discate + ester in the reaction mixture:

[0028] MR = Md / (Ma + Me)

[0029] Here, MR is the molar ratio, Md is the mole of diol in the reaction mixture, Ma is the mole of acid in the reaction mixture, and Me is the mole of ester in the reaction mixture.

[0030] In one or more embodiments, the molar ratio of the reaction mixture is 4 or less, or 3 or less, or 2.5 or less, or 2 or less, or 1.5 or less, or 1 or less, or 1 to 6, or 1.5 to 6, or 2 to 6, or 2.5 to 6, or 1 to 4, or 1.5 to 4, or 2 to 4.

[0031] The inventors have unexpectedly discovered that a polyester having recycled material can be effectively and efficiently manufactured by a method in which a recycled monomer, in particular r-DMT, is combined with other recycled or unused materials and reacted using process parameters, equipment, reaction conditions, etc., more common to TPA-based manufacturing processes to form a polyester having recycled material. Accordingly, in one or more embodiments, the method of the present disclosure comprises the step of reacting a reaction mixture at a temperature of 250°C or higher, 260°C or higher, 270°C or higher, or 275°C or higher for a total average residence time of 30 minutes to 12 hours. In one or more embodiments, the method of the present disclosure comprises the step of reacting a reaction mixture at a temperature of 250°C or higher, 260°C or higher, 270°C or higher, or 275°C or higher for a total average residence time of 4 hours or less, 3 hours or less, 2 hours or less, or 1 hour or less.

[0032] Although the method described herein relates to a single (or more than one) reaction zone where the initial reaction mixture is formed, it will be understood that multiple reaction zones and / or multiple reactors that may be in series may be used. In one or more embodiments, a reactor may define one or more reaction zones, whereas in one or more embodiments, a reaction zone may include one or more reactors. The number of reactors in a reaction zone may be four or fewer, three or fewer, two or fewer, or one or fewer. A reaction zone is defined by a vessel (e.g., a CSTR or a pipe reactor) and is a region or zone where monomeric reactions of the methyl or acid terminus and the glycol occur to esterify or transexchange the methyl or acid terminus. Accordingly, the total average residence time for the reaction step means the sum of the average residence times in all reaction zones and all reactors. The average residence time is referred to as "average" to reflect that the average residence time on a molecular basis has been averaged over the total number of molecules in the reaction mixture. In one or more embodiments, the reaction step is carried out in the presence of a metal-based catalyst. Non-limiting examples of metals for metal-based catalysts include Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu, and combinations thereof. In one or more embodiments, the metal for the metal-based catalyst is selected from the group consisting of titanium, manganese, zinc, tin, and combinations thereof. The amount of catalyst may vary depending on a number of factors, such as reaction temperature.In one or more embodiments, the catalyst may be present in an amount of metal of 1 to 100 ppm, 1 to 50 ppm, 1 to 40 ppm, 1 to 30 ppm, 1 to 20 ppm, 1 to 15 ppm, 1 to 10 ppm, 1 to 5 ppm, 1 to 4 ppm, 1 to 3 ppm, or 1 to 2 ppm based on a part of the reaction mixture.

[0033] The reaction step of the method of the present disclosure comprises reacting a reaction mixture to form a polyester oligomer mixture having a recycled material. In one or more embodiments, the recycled material oligomer mixture has a degree of polymerization of 1 to 30 or 1 to 25 or 1 to 20 or 1 to 15. Those skilled in the art will recognize that in the case of an embodiment that may include multiple reaction bands in series, the degree of polymerization may increase in a continuous band.

[0034] In one or more embodiments, the method of the present disclosure may be carried out as an aspect of a waste polyester recycling process. Accordingly, in one or more embodiments, the method of the present disclosure further comprises a step of depolymerizing waste polyester prior to a feeding step to form a depolymerization product comprising r-DMT. In one or more embodiments, the depolymerization step forms a depolymerization product comprising r-EG. The depolymerization step may form a depolymerization product stream comprising recycled dimethyl terephthalate (r-DMT) and optionally recycled ethylene glycol (r-EG). As used herein, the term “waste polyester” includes, but is not limited to, post-consumption polyester material, post-industrial use polyester material, polyester scrap, polyester selvedge, substandard material, and consumer return polyester material.

[0035] Those skilled in the art will understand that the depolymerization product stream may contain a number of materials based in part on the specific composition of the waste polyester. Accordingly, in one or more embodiments, the depolymerization step further comprises separating r-DMT from the depolymerization product stream to form an r-DMT-rich stream.

[0036] Methods, techniques, and systems for depolymerizing polyester are well known in the art. A particularly suitable method is kameethanol cracking. Kameethanol cracking depolymerization is well known in the art and has been previously described in the references incorporated herein by reference. Polyester recycling methods are generally described in U.S. Patent Application No. 2013 / 0041053, which was assigned to the assignee of this disclosure, and the contents and disclosure thereof are incorporated herein by reference. As used herein, the term "kameethanol cracking" is intended to include the so-called applicable method comprising a step of forming r-DMT through a kameethanol cracking step.

[0037] The method of the present disclosure further comprises the step of polycondensing a mixture of recycled oligomers to form a polyester having recycled materials. Polycondensation is a well-known step in the manufacture of polyesters in which esters and ester oligomers formed by the direct esterification of a diol and / or the ester exchange of an ester are polymerized by condensation polymerization to form a polyester, and any diol that is readily volatilized and removed from the system under polycondensation conditions is removed. Polycondensation may be performed under vacuum at a temperature generally about 230 to about 350°C, preferably about 250 to about 310°C, most preferably about 260 to about 300°C for about 0.1 to about 6 hours, preferably about 0.2 to about 2 hours, until a polymer having a desired degree of polymerization determined by intrinsic viscosity is obtained. The polymer may undergo further polymerization in a solid state.

[0038] As discussed above, the recycled feed for the feeding step of the method of the present disclosure may comprise, in addition to an ester recycled material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof, additional components such as dimethyl isophthalate recycled material (r-DMI) and / or residual catalyst material. Accordingly, in another aspect, the present disclosure relates to a recycled feed composition for the production of a polyester having recycled material. The recycled feed composition of the present disclosure comprises an ester recycled material selected from the group consisting of r-DMT, transesterified r-DMT, and combinations thereof; and one or more of dimethyl isophthalate recycled material (r-DMI) and residual catalyst material. In one or more aspects, the recycled feed composition comprises dimethyl isophthalate recycled material (r-DMI). In one or more aspects, the recycled feed composition comprises residual catalyst material. In one or more embodiments, the recycled feedstock composition comprises a dimethyl isophthalate recycled material (r-DMI) and a residual catalyst material. In one or more embodiments, the recycled feedstock composition comprises r-TPA, for example, r-TPA formed by the hydrolysis of r-DMT.

[0039] In one or more embodiments, the residual catalyst material may be selected from the group consisting of germanium materials, antimony materials, and combinations thereof. In one or more embodiments, r-DMI may be present in an amount of 3,000 ppm or more, 2,000 ppm or more, 1,500 ppm or more, or 1,000 ppm or more based on the part of the recycled feed composition. In one or more embodiments, the residual catalyst material may be present in an amount of 5 to 500 ppm based on the part of the recycled feed composition.

[0040] The inventors have also surprisingly discovered that the method of the present disclosure produces a recycled polyester having unique and useful properties. Accordingly, in another aspect, the present disclosure relates to a polyester having recycled materials, or a recycled polyester, wherein the number of carboxyl ends present in the recycled polyester is less than 25 meq / kg polymer, less than 20 meq / kg polymer, or less than 15 meq / kg polymer. "Carboxyl ends" refers to free carboxyl groups (-COOH) present at the ends of polyester macromolecules. Carboxyl ends can be measured, for example, by acid-based titration using a dissolved polymer sample. In a suitable measurement technique, a weighed sample of the polyester polymer is dissolved in high-temperature ortho-cresol (120°C + / - 5°C), cooled, and then diluted with methylene chloride with a bromo-cresol green indicator solution. An automated titrator optically determines the endpoint and calculates the result.

[0041] In another aspect, the present disclosure relates to a polyester having recycled materials, or a recycled polyester, wherein the diethylene glycol content of the recycled polyester is less than 2.0 wt% or less than 1.8 wt%, less than 1.6 wt% or less than 1.5 wt% or less than 1.4 wt% or less than 1.2 wt% or less than 1.0 wt% or less than 0.8 wt% or less than 0.6 wt% based on the total weight of the polymer. “Diethylene glycol content” refers to the amount of diethylene glycol [(HOCH2CH2)20] present in the recycled polymer. In one or more aspects, at least a portion of the diethylene glycol content is “in-situ” diethylene glycol content, which means that the diethylene glycol used to form the polymer is formed during the polymer formation process (as opposed to being formed individually and intentionally added during the polymer formation process). The diethylene glycol content can be measured, for example, by conventional GC technology or proton NMR technology after hydrolyzing the polymer.

[0042] The following examples further illustrate how the polyester of the present disclosure may be manufactured and evaluated, and are intended to be purely illustrative and not to limit the scope thereof. Unless otherwise indicated, parts are by weight, the temperature is °C (Celsius) or room temperature, and the pressure is atmospheric pressure or near it.

[0043] The present disclosure may be further illustrated by the following examples of preferred embodiments thereof, but it will be understood that such examples are included merely for illustrative purposes and are not intended to limit the scope of the present disclosure unless specifically indicated otherwise.

[0044] Examples

[0045] Example 1 - Oligomer Synthesis Section

[0046] The oligomers used to produce the high polymer were synthesized in a 2-gallon stainless steel autoclave with a partial condenser heated with hot oil. For the series of experiments shown in Table 1, the reaction process was as follows: the raw materials were loaded into the reactor, sealed, heated to 260°C, pressurized to 30 psig, the partial condenser was heated to 130°C, and once the system reached the temperature, the reaction was run for 8 hours. Subsequently, the reactor was heated to the target composition of the final material containing 5% IPA-modified PET, and a titanium tetra-isopropoxide catalyst was added so that the content of the final polymer was 15 ppm in all cases.

[0047] [Table 1]

[0048]

[0049] 100 g of oligomer was loaded into a single-necked 500 mL round-bottom flask. The target level of antimony catalyst was added to the flask in an ethylene glycol solution. A stainless steel stirring device consisting of a 1 / 4" diameter shaft attached to a single 2.5" diameter stirring blade was inserted into the flask, and then a glass polymer head was mounted on the flask. The polymer head, consisting of a standard taper 24 / 40 male joint, was connected to the reaction flask; a side arm positioned at approximately 45° relative to the neck of the flask to allow for the removal of volatile substances; and a glass tubing section extending over the neck of the flask through which the stirring shaft passed. A Teflon bushing and a rubber hose were fitted to the section through which the stirring shaft passed to provide a vacuum seal around the stirring shaft. The shaft was rotated by a 1 / 8 horsepower motor connected by a flexible "universal" joint. The side arm was connected to a vacuum system consisting of a dry ice-cooled condenser and a vacuum pump. The pressure inside the reaction flask was controlled by venting nitrogen into a vacuum stream. The reaction flask was heated using a molten metal bath. All reaction parameters were monitored and controlled using a distributed data acquisition and control system. Table 2 shows the reaction sequence used by the automated control system, and a change in step 8 was used to produce a low-viscosity material through solid stating.

[0050] [Table 2]

[0051]

[0052] After polymerization, each polymer was removed from the blades of the stirring shaft and ground in a hammer mill to a particle size small enough to pass through a screen perforated with 6 mm holes. All tests and solid-state markings were performed on the granules.

[0053] Table 3 below details examples of the final IV for materials produced by varying amounts of DMT added to the TPA-based process. In Table 2, %DMT refers to the molar percentage in the reaction where TPA units are replaced by DMT. In this document, the intrinsic viscosity of the polyester was measured in 60 / 40 (wt / wt) phenol / tetrachloroethane at a concentration of 0.5 g / dL at 25°C and is reported in dL / g units. The metal content of the material was measured by X-ray fluorescence in a manner similar to ASTM D6247-18 (modified for sample matrix and analyte of interest). The use and amount of DMT added to the system do not have a negative effect on the IV build of the material.

[0054] [Table 3]

[0055]

[0056] To measure the effect of DMT on IV lift, a standard solid-state stating process (held at 220°C and 1 mmHg for 24 hours) was performed. The results shown in Table 4 demonstrate that, as with the resin-based process, there is no negative effect of adding DMT to the PTA-based process. These results are unexpected considering the poor reactivity of any residual methyl terminus in solid-state stating. Without being bound by any theory, it is believed that the high temperature and long residence time in the first reactor can reduce the methyl terminus content to a point where it no longer interferes with solid-state IV build.

[0057] [Table 4]

[0058]

[0059] To avoid any doubt, it is explicitly provided that the information and description of the present invention regarding features or elements of one aspect of the present disclosure is identified as applicable to and supporting such features and elements when described in relation to other aspects of the present disclosure.

[0060] The foregoing description of various aspects of the present disclosure is provided for illustrative and illustrative purposes only. It is not intended to make the present disclosure complete or limit it to the exact aspects disclosed. Numerous modifications or variations are possible in light of the foregoing teachings. The aspects discussed are selected and described to best illustrate the principles of the present disclosure and their practical application, enabling those skilled in the art to utilize the present disclosure in various aspects and various modifications considered suitable for a particular use. All such modifications and variations fall within the scope of the present disclosure as determined by the appended claims, when interpreted in a fair, lawful, and equitable manner.

Claims

Claim 1 A method for manufacturing a polyester having recycled content, comprising: a feeding step of supplying a recycled feed containing an ester recycling material selected from the group consisting of recycled dimethyl terephthalate (r-DMT), ester-exchanged r-DMT, and combinations thereof to one or more reaction zones to form a reaction mixture containing recycled content in said one or more reaction zones; a reaction step of reacting said reaction mixture to form a polyester oligomer mixture having recycled content; and a step of polycondensing the recycled content oligomer mixture to form a polyester having recycled content, wherein the feeding step further comprises a step of supplying an unused feed containing one or more virgin diol components to one or more reaction zones, said unused feed further comprises an unused diol component, said unused diol component being terephthalic acid (TPA) of 90 mol% or more based on the total diol content of said unused feed, and said reaction step comprising a step of reacting the reaction mixture at a temperature of 250°C or higher for a total average residence time of 30 minutes to 12 hours. Claim 2 A manufacturing method according to claim 1, wherein the supply step further comprises the step of supplying a diol recycling material selected from the group consisting of recycled ethylene glycol (r-EG), recycled diethylene glycol (r-DEG) and combinations thereof to one or more reaction zones. Claim 3 A method of manufacturing according to claim 1, wherein the recycled feed further comprises a dimethyl isophthalate recycled material (r-DMI). Claim 4 A method of manufacturing according to claim 1, wherein the recycled feed further comprises a residual catalyst material selected from the group consisting of germanium material, antimony material, and combinations thereof. Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 A method of manufacturing according to claim 1, wherein the unused acidic component further comprises isophthalic acid. Claim 11 A method for manufacturing according to claim 1, wherein the reaction step is carried out in the presence of a metal-based catalyst having a metal selected from the group consisting of Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu and combinations thereof. Claim 12 In claim 1, the unused diol component of the unused supply comprises ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,10-decanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polytetrahydrofuran, polyoxymethylene, isosorbide, 2,2,4,4-tetraalkylcyclobutanediol including 1,3- and 1,4-cyclohexanedimethanol (CHDM), 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethylcyclobutanediol (TMCD), neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, glycerol, trimethylolpropane, pentaeryltritol, A method of preparation comprising one or more of resorcinol, hydroquinone, catechol, and isomers and combinations thereof. Claim 13 A method of manufacturing according to claim 1, wherein the diol component of the unused feed comprises one or more diols selected from the group consisting of ethylene glycol, diethylene glycol, neopentyl glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD), cyclohexanedimethanol (CHDM), and isomers and combinations thereof. Claim 14 A manufacturing method according to claim 1, comprising, prior to the supply step, a depolymerization step of depolymerizing waste polyester to form a depolymerization product containing r-DMT, wherein the depolymerization step is performed by methanolysis. Claim 15 A manufacturing method according to claim 1, wherein the ester recycling material in the supply step is supplied in an amount sufficient to account for 1 to 100 mol% based on the total discrete moles of 1,4-dicarboxybenzene equivalents in the polyester having the recycled material. Claim 16 A manufacturing method according to claim 1, wherein the step of supplying an unused feedstock precedes the step of supplying a recycled feedstock; and the manufacturing method further comprises the step of reacting at least a portion of the unused feedstock in a reactor to form an unused polyester oligomer, either before or simultaneously with the step of supplying the recycled feedstock. Claim 17 A method for manufacturing according to claim 1, further comprising, prior to the supply step, a step of pre-reacting at least a portion of r-DMT with one or more diols selected from the group consisting of ethylene glycol, diethylene glycol, neopentyl glycol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,4-cyclobutanediol, and isomers and combinations thereof to form ester-exchanged r-DMT. Claim 18 A method of manufacturing according to claim 17, wherein the pre-reaction step is carried out in the presence of a metal-based catalyst having a metal selected from the group consisting of Sb, Ti, Sn, Mo, Ge, Zn, Co, Mn, Cd, Al, Li, Pb, Mg, Ca, Ag, Na, Ce, Ba, Hg, Fe, Cu and combinations thereof. Claim 19 A recycled feed composition for the manufacture of a polyester having recycled material, wherein the recycled feed comprises one or more of the following: an ester recycled material selected from the group consisting of recycled dimethyl terephthalate (r-DMT), ester-exchanged r-DMT, and combinations thereof; a terephthalic acid recycled material (r-TPA); a dimethyl isophthalate recycled material (r-DMI); and a residual catalyst material selected from the group consisting of germanium material, antimony material, and combinations thereof. Claim 20 In paragraph 19, the recycled feed composition comprises dimethyl isophthalate recycled material (r-DMI) in an amount of 3,000 ppm or more; or a residual catalyst material is present in an amount of 5 to 500 ppm based on a part of the recycled feed composition.

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