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WO2025188873A1 - Composition de polyester pour récipients moulés par extrusion-soufflage contenant un polyester post-consommation et son procédé de préparation - Google Patents

Composition de polyester pour récipients moulés par extrusion-soufflage contenant un polyester post-consommation et son procédé de préparation

Info

Publication number
WO2025188873A1
WO2025188873A1 PCT/US2025/018539 US2025018539W WO2025188873A1 WO 2025188873 A1 WO2025188873 A1 WO 2025188873A1 US 2025018539 W US2025018539 W US 2025018539W WO 2025188873 A1 WO2025188873 A1 WO 2025188873A1
Authority
WO
WIPO (PCT)
Prior art keywords
copolyester
blow molded
extrusion blow
rpet
container
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/US2025/018539
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English (en)
Other versions
WO2025188873A8 (fr
Inventor
Xinfei YU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Auriga Polymers Inc
Original Assignee
Auriga Polymers Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Auriga Polymers Inc filed Critical Auriga Polymers Inc
Publication of WO2025188873A1 publication Critical patent/WO2025188873A1/fr
Publication of WO2025188873A8 publication Critical patent/WO2025188873A8/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/0005—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor characterised by the material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0017—Combinations of extrusion moulding with other shaping operations combined with blow-moulding or thermoforming
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/02—Combined blow-moulding and manufacture of the preform or the parison
    • B29C49/04—Extrusion blow-moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0085—Copolymers

Definitions

  • This invention relates to polyester polymers, and more particular to polyethylene terephthalate copolyesters for transparent extrusion blow molded containers that contain post-consumer polyester.
  • Aromatic polyesters generally are semi-crystalline and have low melt strength.
  • Containers made from polyethylene terephthalate (PET), with minor amounts of a modifying comonomer, by the injection stretch molding process (ISBM) are the most common transparent container on the market.
  • ISBM process is limited to uniform shapes and cannot produce bottles with a handle. Handles are a desirable feature for larger bottles and containers to facilitate handling by the consumer. Large bottles and containers with handles can be produced by the extrusion blow molding (EBM) process.
  • EBM extrusion blow molding
  • a typical EBM process involves: a) melting the resin in an extruder b) extruding the molten resin through a die to form a tube of molten polymer (a parison) c) clamping a mold having the desired finished shape around the parison d) blowing air into the parison, causing the extrudate to stretch and expand to fill the mold e) cooling the molded container f) ejecting the container from the mold and g) removing excess plastic (flash / flashing) from the container.
  • the hot parison that is extruded in this process often must hang for several seconds under its own weight prior to the mold being clamped around it.
  • the extrudate must possess high melt strength — a feature that enables the material to resist stretching, flowing, and sagging that would cause uneven distribution in the parison and thinning of the parison walls.
  • the sag of the extruded parison is directly related to the weight of the parison, whereby larger and heavier parisons will have a greater tendency to sag.
  • Melt strength is directly related to the polyester resin's viscosity, under zero shear rate, and temperature when the molten extrudate exits the die.
  • an optimal-polyester resin tailored for EBM end uses, must have a rheology such that the viscosity at the shear rates associated with the extrusion process, generally 100 to 1000 s’ 1 , is lower than the viscosity at zero shear rate (i.e. it exhibits shear thinning).
  • the molten polyester cannot thermally crystallize on cooling; otherwise, a cloudy container is produced.
  • the EBM process produces waste from the flash that has to be cut off the molded container (e.g. clamped sites). This waste (or recycled material) from the EBM process must be ground and blended with virgin resin and dried prior to re-extrusion. This waste (regrind) usually comprises about 40-50% of the feedstock in the EBM manufacturing process.
  • high melt strength copolyester resins with an ultra-high molecular weight (IV > 1.1 dl/g) that contain a low amount of IPA or CHDM can be used to provide the necessary melt strength as they exhibit some degree of shear thinning (US 9,399,700).
  • These ultra-high IV polyester resins have to be processed at higher temperatures which cause the resin to thermally degrade giving not only an increased yellowness in the container but a narrower EBM processing window. Decreasing the temperature leads to melt fracture and a marked increase in the pressure required from the extruder to feed molten polymer to the die.
  • these tough resins are more difficult to cut and to cleanly remove flash from the finished container.
  • W02023/017038 discloses a process in which the rPET flakes are solid state polymerized to the high TV range of 0.9 to 1.4 dL/g required for EBM processes.
  • US2023/0182365 discloses a process in which the rPET flakes are reactively extruded with chain extenders or chain branchers to increase the molecular weight prior to a final solid state polymerization process.
  • US 11,254,797 discloses a process in which the rPET is extruded in the presence of water to reduce its molecular weight prior to solid state polymerization.
  • the present invention relates to a process to manufacture polyester resin for extrusion blow molded bottles comprising at least 25% of PCR content.
  • the present invention relates to the process of preparing EBM bottles from this composition.
  • the present invention relates to the EBM containers made from this composition. DESCRIPTION OF THE INVENTION
  • Polyester EBM resins are generally prepared by the addition of comonomers to retard the crystallization rate of the polyester resin together with a multifunctional branching comonomer to increase the melt strength and provide the resin with a shear thinning rheological behavior.
  • polyester compositions suitable for use in this invention typically comprise:
  • a diacid component comprising 95 to 100 mole % of di carboxylic acid residues based on the total mole % of dicarboxylic acid residues in the polyester compositions, and
  • glycol component comprising 90 to 100 mole % of glycol residues based on the total mole percent of glycol residues in the polyester compositions
  • the di carboxylic acid residues may comprise terephthalic acid, naphthalene dicarboxylic acids or mixtures thereof.
  • the glycol residues comprise ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol, branched aliphatic glycols or mixtures thereof.
  • the copolyester contains from about 20 wt. % to about 50 wt. % recycled polyethylene terephthalate (rPET) and an intrinsic viscosity of at least 0.9 dL/g.
  • the di carboxylic acid component may comprise up to 5 mole % of one or more modifying aromatic dicarboxylic acids chosen from 4,4'-biphenyldicarboxylic acid, 1,4- naphthalene dicarboxylic acid, 1,5- naphthalene dicarboxylic acid, 2,6- naphthalene dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, trans-4,4'-stilbenedicarboxylic acid, heterocyclic dicarboxylic acid and esters thereof.
  • At least one additive can be added to the copolyester chosen from colorants, toners, dyes, mold release agents, flame retardants, plasticizers, stabilizers, impact modifiers, or a mixture thereof.
  • the copolyester may also comprise up to 5 mole % of one or more aliphatic dicarboxylic acids chosen from malonic, succinic, glutaric, adipic, pimelic, suberic, octanoic, azelaic, sebacic, dodecanedioic-dicarboxylic acids, diethyl-di-n-propyl malonate, dimethyl benzylmalonate, 2,2-dimethyl-malonic acid and 2,3-dimethyl glutaric acid.
  • aliphatic dicarboxylic acids chosen from malonic, succinic, glutaric, adipic, pimelic, suberic, octanoic, azelaic, sebacic, dodecanedioic-dicarboxylic acids, diethyl-di-n-propyl malonate, dimethyl benzylmalonate, 2,2-dimethyl-malonic acid and 2,3-dimethyl glut
  • An extrusion blow molded process for forming a container may typically comprise:
  • glycol component comprising 90 to 100 mole % of glycol residues based on the total mole percent of glycol residues in the polyester compositions
  • the process may further comprise grinding the scrap from the container and then mixing with the resin in step (a).
  • the container may include, but is not limited to, bottles, bags, vials, tubes, and jars.
  • the melting point of the resin is between 235°C to 255°C.
  • the dicarboxylic acid residues comprise terephthalic acid, naphthalene dicarboxylic acids or mixtures thereof, and the glycol residues comprise ethylene glycol, diethylene glycol, 1,4-cyclohexanedimethanol, branched aliphatic glycols or mixtures thereof.
  • the copolyester contains from about 20 wt. % to about 50 wt.
  • the dicarboxylic acid component may comprise up to 5 mole % of one or more modifying aromatic di carboxylic acids chosen from 4,4'-biphenyldicarboxylic acid, 1,4- naphthalene dicarboxylic acid, 1,5- naphthalene dicarboxylic acid, 2,6- naphthalene dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, trans-4,4'-stilbenedicarboxylic acid, heterocyclic dicarboxylic acid and esters thereof.
  • At least one additive can be added to the copolyester chosen from colorants, toners, dyes, mold release agents, flame retardants, plasticizers, stabilizers, impact modifiers, or a mixture thereof.
  • the copolyester may also comprise up to 5 mole % of one or more aliphatic dicarboxylic acids chosen from malonic, succinic, glutaric, adipic, pimelic, suberic, octanoic, azelaic, sebacic, dodecanedioic-dicarboxylic acids, diethyl-di-n-propyl malonate, dimethyl benzylmalonate, 2,2-dimethyl-malonic acid and 2,3-dimethyl glutaric acid.
  • the container color is provided in Table 2
  • the bottle drop performance is provided in Table 3.
  • An extrusion blow molded container comprising a copolyester may comprise:
  • a diacid component comprising 95 to 100 mole % of di carboxylic acid residues based on the total mole % of dicarboxylic acid residues in the polyester compositions, and
  • glycol component comprising 90 to 100 mole % of glycol residues based on the total mole percent of glycol residues in the polyester compositions
  • the dicarboxylic acid residues may comprise terephthalic acid, naphthalene dicarboxylic acids or mixtures thereof.
  • the glycol residues comprise ethylene glycol, di ethylene glycol, 1,4-cyclohexanedimethanol, branched aliphatic glycols or mixtures thereof.
  • the copolyester contains from about 20 wt. % to about 50 wt. % recycled polyethylene terephthalate (rPET) and an intrinsic viscosity of at least 0.9 dL/g.
  • the di carboxylic acid component may comprise up to 5 mole % of one or more modifying aromatic dicarboxylic acids chosen from 4,4'-biphenyldicarboxylic acid, 1,4- naphthalene di carboxylic acid, 1,5- naphthalene dicarboxylic acid, 2,6- naphthalene dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, trans-4,4'-stilbenedicarboxylic acid, heterocyclic dicarboxylic acid and esters thereof.
  • At least one additive can be added to the copolyester chosen from colorants, toners, dyes, mold release agents, flame retardants, plasticizers, stabilizers, impact modifiers, or a mixture thereof.
  • the copolyester may also comprise up to 5 mole % of one or more aliphatic dicarboxylic acids chosen from malonic, succinic, glutaric, adipic, pimelic, suberic, octanoic, azelaic, sebacic, dodecanedioic-dicarboxylic acids, diethyl-di-n-propyl malonate, dimethyl benzylmalonate, 2,2-dimethyl-malonic acid and 2,3-dimethyl glutaric acid.
  • aliphatic dicarboxylic acids chosen from malonic, succinic, glutaric, adipic, pimelic, suberic, octanoic, azelaic, sebacic, dodecanedioic-dicarboxylic acids, diethyl-di-n-propyl malonate, dimethyl benzylmalonate, 2,2-dimethyl-malonic acid and 2,3-dimethyl glut
  • the container has a drop height of more than 160 cm when tested according to ASTM D 2463-95, procedure B, Bruceton Staircase Method, after two weeks, and has a % haze of less than 3%.
  • the container may include, but is not limited to, bottles, bags, vials, tubes, and jars.
  • the container color is provided in Table 2, and the bottle drop performance is provided in Table 3.
  • a method for manufacturing copolyester polymer for extrusion blow molded containers containing recycled polyethylene terephthalate (rPET) in a continuous polymerization unit comprising the following steps: a) feeding said rPET to an extruder, and b) melting said rPET in said extruder, and c) extruding said molten rPET into a molten stream containing oligomers from said continuous polymerization unit creating a prepolymer, and d) polymerizing said prepolymer thereby producing copolyester containing rPET, and wherein the color of the said copolyester containing rPET is adjusted during said polymerization step (d) to match the color of the copolyester manufactured without said rPET.
  • rPET recycled polyethylene terephthalate
  • the container may include, but is not limited to, bottles, bags, vials, tubes, and jars.
  • the container color is provided in Table 2, and the bottle drop performance is provided in Table 3.
  • polyyester as used herein, is intended to include “copolyesters” and is understood to mean a synthetic polymer prepared by the reaction of one or more difunctional carboxylic acids and/or multifunctional carboxylic acids with one or more difunctional hydroxyl compounds and/or multifunctional hydroxyl compounds, for example, branching comonomers.
  • the difunctional carboxylic acid can be a dicarboxylic acid
  • the difunctional hydroxyl compound can be a dihydric alcohol such as, for example, glycols and diols.
  • glycol as used herein includes, but is not limited to, diols, glycols, and/or multifunctional hydroxyl compounds, for example, branching comonomers.
  • the difunctional carboxylic acid may be a hydroxy carboxylic acid such as, for example, p-hydroxybenzoic acid
  • the difunctional hydroxyl compound may be an aromatic nucleus bearing 2 hydroxyl substituents such as, for example, hydroquinone, resorcinol or other heterocyclic diols, and isosorbide, for example.
  • residue means any organic structure incorporated into a polymer through a polycondensation and/or an esterification reaction from the corresponding monomer.
  • replicaating unit means an organic structure having a dicarboxylic acid residue and a diol residue bonded through a carbonyloxy group.
  • the dicarboxylic acid residues may be derived from a dicarboxylic acid monomer or its associated acid halides, esters, salts, anhydrides, and/or mixtures thereof.
  • dicarboxylic acid is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, and/or mixtures thereof, useful in a reaction process with a diol to make polyester.
  • terephthalic acid is intended to include terephthalic acid itself and residues thereof as well as any derivative of terephthalic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, and/or mixtures thereof or residues thereof useful in a reaction process with a diol to make polyester.
  • the polyesters used in the present invention typically can be prepared from dicarboxylic acids and diols which react in substantially equal proportions and are incorporated into the polyester polymer as their corresponding residues.
  • the polyesters of the present invention therefore, can contain substantially equal molar proportions of acid residues (100 mole %) and glycol (and/or multifunctional hydroxyl compound) residues (100 mole %) such that the total moles of repeating units is equal to 100 mole %.
  • the mole percentages provided in the present disclosure therefore, may be based on the total moles of acid residues, the total moles of diol residues, or the total moles of repeating units.
  • a polyester containing 1 mole % isophthalic acid means the polyester contains 1 mole % isophthalic acid residues out of a total of 100 mole % acid residues.
  • polyester containing 1.5 mole % di ethylene glycol out of a total of 100 mole % glycol residues has 1.5 moles of di ethylene glycol residues among every 100 moles of glycol residues.
  • the glycol component employed in making the polyesters useful in the invention can comprise, consist essentially of, or consist of ethylene glycol and one or more difunctional glycols chosen from diethylene glycol, 1,2- propanediol, 1,5 -pentanediol, 1,6-hexanediol, branched aliphatic glycols such as 2- methyl-1, 3 -propane diol, 2-ethyl- 1,3 -propane diol, 2-butyl- 1,3 -propane diol, 2,2'-dimethyl- 1,3-propanediol, 2-methyl-l,4-butanediol, 2-ethyl- 1,4-butanediol, 2-butyl- 1,4-butanediol, 3-methyl-l,5-pentanediol, 2,4-dimethyl-l,5-pentanediol and mixtures thereof.
  • the preferred glycol chosen from diethylene
  • the dicarboxylic acid component of the polyesters useful in the invention can comprise up to 5 mole %, or up to 1 mole % of one or more modifying aromatic dicarboxylic acids.
  • modifying aromatic dicarboxylic acids which may be used in this invention include, but are not limited to, 4,4'-biphenyldicarboxylic acid, 1,4-, 1,5-, 2,6-, 2,7- naphthalenedicarboxylic acid, and trans-4,4'-stilbenedicarboxylic acid, and esters thereof.
  • Heterocyclic dicarboxylic acid for example 2,5-furan dicarboxylic acid may also be used.
  • the preferred modifying aromatic dicarboxylic acid is 2,6-naphthalene dicarboxylic acid.
  • the dicarboxylic acid component of the polyesters useful in the invention can be further modified with up to 5 mole % or up to 1 mole % of one or more aliphatic dicarboxylic acids containing 2 to 16 carbon atoms, such as, for example malonic, succinic, glutaric, adipic, pimelic, suberic, octanoic, azelaic, sebacic, dodecanedioic- dicarboxylic acids, diethyl-di-n-propyl malonate, dimethyl benzylmalonate, 2,2- dimethyl-malonic acid and 2,3 -dimethyl glutaric acid.
  • the preferred aliphatic dicarboxylic acid is adipic acid.
  • the polyesters of the invention can also comprise at least one chain extender.
  • Suitable chain extenders include, but are not limited to, multifunctional (including, but not limited to, bifunctional) isocyanates, multifunctional epoxides, including for example, epoxylated novolacs, and phenoxy resins.
  • chain extenders may be added at the end of the polymerization process or after the polymerization process. If added after the polymerization process, chain extenders can be incorporated by compounding or by addition during conversion processes such as injection molding or extrusion.
  • the amount of chain extender used can vary depending on the specific monomer composition used and the physical properties desired but is generally about 0.1 to about 5 % by weight, or about 0. 1 to about 2 % by weight, based on the total weight of the polyester.
  • polyester compositions and the polymer blend compositions useful in the invention may also contain any amount of at least one additive, for example, from 0.01 to 2.5% by weight of the overall composition common additives such as colorants, dyes, mold release agents, flame retardants, plasticizers, stabilizers, including but not limited to, UV stabilizers, thermal stabilizers and/or reaction products thereof, and impact modifiers.
  • additives such as colorants, dyes, mold release agents, flame retardants, plasticizers, stabilizers, including but not limited to, UV stabilizers, thermal stabilizers and/or reaction products thereof, and impact modifiers.
  • Examples of typical commercially available impact modifiers well known in the art and useful in this invention include, but are not limited to, ethylene/propylene terpolymers, functionalized polyolefins such as those containing methyl acrylate and/or glycidyl methacrylate, styrene-based block copolymeric impact modifiers, and various acrylic core/shell type impact modifiers.
  • ethylene/propylene terpolymers functionalized polyolefins such as those containing methyl acrylate and/or glycidyl methacrylate
  • styrene-based block copolymeric impact modifiers styrene-based block copolymeric impact modifiers
  • various acrylic core/shell type impact modifiers for transparent EBM containers the refractive index of these additives must closely match the refractive index of the polyester composition to prevent a hazy container. Residues of such additives are also contemplated as part of the polyester composition.
  • a bluing toner can be used to reduce the yellowness of the resulting polyester polymer melt phase product.
  • Such bluing agents include cobalt salts, blue inorganic and organic toner(s) and the like.
  • red toner(s) can also be used to adjust the redness.
  • Organic toner(s), e.g., blue and red organic toner(s) can be used.
  • the organic toner(s) can be fed as a premix composition.
  • the premix composition may be a neat blend of the red and blue compounds or the composition may be pre-dissolved or slurried in one of the polyester's raw materials, e.g., ethylene glycol.
  • the total amount of added toner components depends on the amount of inherent yellow color in the base polyester and the efficacy of the toner. Generally, a concentration of up to about 15 ppm of combined organic toner components and a minimum concentration of about 0.5 ppm are used, with the total amount of bluing additive typically ranging from about 0.5 ppm to about 10 ppm.
  • Conventional production of polyesters can be achieved by a batch, semi-continuous, or continuous process. A typical polyesterification process is comprised of multiple stages and commercially carried out in one of two common pathways.
  • the initial stage of the process reacts the dicarboxylic acids with one or more diols at a temperature of about 200° C to about 250° C to form macro-monomeric structures and a small condensate molecule, water. Because the reaction is reversible, the water is continuously removed to drive the reaction to the desired first stage product. The branching comonomer is normally added at this stage of the process.
  • an Ester Interchange process is used to react the ester groups of the diesters and diols with certain well known catalysts, as manganese acetate, zinc acetate, or cobalt acetate. After completing the ester interchange reaction these catalysts are sequestered with a phosphorus compound, such as phosphoric acid, to prevent degradation during the polycondensation process.
  • the catalysts generally used for the polycondensation reaction are compounds containing antimony, germanium, aluminum, titanium or other catalysts known to those skilled in the art, or mixtures thereof.
  • the specific additives used and the point of introduction during the reaction is known in the art and does not form a part of the present invention. Any conventional system may be employed and those skilled in the art can select among various commercially-available systems for the introduction of additives so as to achieve an optimal result.
  • the polyester pellets can be further polymerized to a higher molecular weight by well-known solid state polymerization processing techniques.
  • the terephthalic acid and/or ethylene glycol are preferably derived from a biomass feedstock rather than a petroleum based feedstock.
  • the use of chemically recycled terephthalic acid (or dimethyl terephthalate) and ethylene glycol from post-consumer polyester waste is also preferred for the polyesters of this invention.
  • Another preferred method of manufacturing the polyester resins of this invention utilizes bis-(hydroxyethyl)-terephthalate, purified from the reaction product of glycolysis of postconsumer polyester waste — this monomer can be added to the polymerization process, preferably prior to the polycondensation stages.
  • polyester compositions suitable for use in this invention include those having an intrinsic viscosity of at least about 0.90 dl/g, preferably at least about 1.0 dl/g, and more preferably between about 0.9 and about 1.2 dl/g.
  • Lower intrinsic viscosity resins have insufficient melt strength for an EBM process, whereas higher intrinsic viscosity resins have too high a melt viscosity at the extrusion temperatures above which there is thermal degradation and a loss of molecular weight.
  • the branching monomer residues are chosen from at least one of the following: pentaerythritol, trimethylolpropane, trimethylolethane, trimellitic acid, trimellitic anhydride and/or benzene- 1, 3, 5 -tricarboxylic acid.
  • the branching comonomer can be present in an amount ranging from 50 to 2000 pmol based on the copolyester.
  • this invention relates to a process for preparing extrusion blow molded containers.
  • the extrusion blow molding process can be accomplished via any EBM manufacturing process known in the art.
  • a typical description of extrusion blow molding manufacturing process involves: 1) melting the resin in an extruder 2) extruding the molten resin through a die to form a tube of molten polymer (i.e.
  • fl ash/fl ashing removing excess plastic (commonly referred to as fl ash/fl ashing) from the container.
  • container as used herein is understood to mean a receptacle in which material is held or stored.
  • Containers include, but are not limited to, bottles, bags, vials, tubes, and jars. Applications in the industry for these types of containers include, but are not limited to, food, beverage, cosmetics, household or chemical containers, and personal care applications.
  • bottle as used herein, is understood to mean a receptacle containing resin which is capable of storing or holding liquid.
  • the exact resin formulation must provide a melt such that when extruded has a high melt strength capable of resisting stretching and flowing, sagging, or other undesirably aspects that would lead to uneven material distribution in the parison and thinning of the parison walls.
  • Melt strength is directly related to the polyester resin's viscosity, under zero shear rate, and temperature when the molten extrudate exits the die.
  • a resin with high melt strength, or high melt viscosity at zero shear rate is too viscous to be extruded in the extruder and pumped through the die without using high temperatures which cause the polymer to degrade and lose its melt viscosity.
  • an optimal polyester resin designed for EBM end uses, must have a rheology such that the viscosity at the shear rates associated with the extrusion process, generally 100 to 1000 s’ is lower than the viscosity at zero shear rate (i.e. exhibits shear thinning).
  • the molten polyester should not thermally crystallize; otherwise, a cloudy container is produced.
  • the EBM process produces waste from the flash that has to be cut from the molded container where, for instance, it has been clamped. This waste from the EBM process must be ground and mixed with the virgin resin and dried prior to re-extrusion. Therefore, the designed resin of interest has to possess and maintain a low level of crystallinity such that it does not agglomerate during drying.
  • the polyester resins of this invention must be semicrystalline (i.e. exhibit a melting endotherm as detected by Differential Scanning Calorimetry).
  • the melting point for an EBM resin should be in the range of 225-255° C.
  • Another parameter that must be met by the resin relates to the drop resistance of an EBM container filled with liquid when dropped from a height of 4 feet (122 cm). After such a drop test, it is expected that no more than one out of ten containers break, split or leak. As copolyesters age with time, it is important that the drop resistance is measured after several weeks, e.g. 2 to 4 weeks, from manufacture.
  • TEST METHODS a The Intrinsic Viscosity of the polyesters are measured according to ASTM D 460396, and reported in units of dL/g. b. Hie haze of the bottle walls was measured with a Hunter Lab ColorQuest II instrument. D65 illuminant was used with a CIE 1964 10° standard observer. The haze is defined as the percent of tire CIE Y diffuse transmittance to the CIE Y total transmission. The color of the preform and bottle walls was measured with the same instrument and is reported using the CIELAB color scale. L* is a measure of brightness, a* is a measure of redness (+) or greenness (-) and b* is a measure of yellowness (+) or blueness (-).
  • the drop resistance of the containers was measured according to ASTM D 2463- 95, procedure B, Bruceton Staircase Method.
  • the containers were filed with 2.6 liter of water (23 °C) prior to dropping.
  • the containers were stored at 23 °C and 50% Relative Humidity for aging (1 day, 1 week, 2 weeks, 3 weeks, 4 weeks, etc.).
  • the content of the diacids and diols, including DEG (diethylene glycol), in the polymer was determined from proton nuclear magnetic spectra (1H MNR), using a JOEL ECX-300, 300 MHz instrument.
  • General sample preparation was as follows:
  • polyester 20 mg is placed in a suitable 2 mL glass reaction vessel or vial with 1 mL of 10: 1 chloro form-d:TFA-d [Cambridge Isotope Laboratories, Inc. Chloroform-d (d, 98.9%)+0.05% V/V TMS: Cambridge Isotope Laboratories, Inc. Tri fluoro acetic acid-d (d, 99.5%)] and capped.
  • the reaction vessel / vial is placed on a heating block at a temperature of 100°C for approximately 10 minutes, or until sample is fully solvated.
  • the sample is then removed from the heat block and placed in the hood to equilibrate to RT.
  • the solvated sample is then transferred to a standard NMR tube and analyzed via a pre-defined NMR experimental protocol. Resultant spectral integrations were worked-up via Excel macros in order to determine the reported monomer contents.
  • a 90 mm Bekum H-155 Continuous EBM Machine fitted with a barrier screw was used to produce model EBM containers. These containers were standard 2.63 liter, rectangular handleware containers weighing 105 g. The extrusion temperature was adjusted between 245 and 260° C to obtain an even polymer distribution in the containers. The polyesters were dried to a moisture level of less than 50 ppm prior to extrusion.
  • the control EBM resin was made on a commercial continuous polymerization (CP) PET unit manufacturing.
  • the target amorphous IV of this copolyester is 0.72 dL/g, with 5.3 mole % isophthalic acid (IP A) and 2.1 mol % diethylene glycol (DEG); antimony trioxide is used as the polycondensation catalyst with process conditions typical of standard operating procedures known in the art.
  • the amorphous copolyester was further polymerized in the solid state to achieve the target IV of 1.25 dL/g.
  • the EBM extrusion conditions used to produce bottles are summarized in Table 1, the bottle color provided in Table 2, and the bottle drop performance provided in Table 3.
  • Example 2 The same process as used in Example 1 was changed with 25% rPET (EcoMex) flake melted in an extruder and metered into the secondary esterifier through a 20- micron filter. This rPET flake replaced 25% of the monomer, made in the primary esterifier, to maintain a constant throughput in the CP unit.
  • the IPA, DEG and color of the rPET was measured and the amount of IPA, DEG and toners adjusted in the CP unit to meet the target values of these parameters (IPA, DEG and color) as the 100% virgin PET product.
  • the EBM bottle extrusion conditions are summarized in Table 1, the bottle color provided in Table 2, and the bottle drop performance provided in Table 3.
  • EcoMex rPET having an IV of 0.81 dL/g was dried, but not solid state polymerized, and mixed with the EBM resin made in Example 1, dried and extruded into EBM bottles.
  • the EBM extrusion conditions are summarized in Table 1, and the bottle color provided in Table 2.
  • EcoMex rPET was solid state polymerized to 1.25 dL/g and 25 % mixed with 75 % the EBM resin made in Example 1, dried and extruded into EBM bottles.
  • the EBM extrusion conditions are summarized in Table 1, and the bottle color provided in Table 2, and the initial bottle drop performance provided in Table 3.
  • EcoMex rPET flake 25 % was compounded with the EBM resin made in Example 1. This polymer was solid state polymerized to 1.25 dL/g, dried and extruded into EBM bottles.
  • the EBM extrusion conditions are summarized in Table 1, and the bottle color provided in Table 2, and the bottle drop performance provided in Table 3.
  • Example 2 produced resin with 25% rPET made EBM bottles comparable to the control virgin type 5507 resins (Example 1). The slight increase in yellowness can be adjusted by the addition of toners in the polymerization process.
  • Example 3 in which the rPET was not solid state polymerized to the same IV as the virgin EBM resin had low melt strength, such that EBM bottles could not be made.
  • Example 4 in which the rPET was solid stated to the same IV as the virgin EBM resin had high haze and exhibited black specks in the bottle walls.
  • Example 5 in which the rPET was compounded with the virgin EBM resin, had unacceptable color (yellowness).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Polyesters Or Polycarbonates (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)

Abstract

L'invention concerne un copolyester pour un récipient moulé par extrusion-soufflage qui comprend d'environ 60 % en poids à environ 90 % en poids de copolyester, comprenant : (i) un composant diacide comprenant de 95 à 100 % en moles de résidus d'acide dicarboxylique par rapport au % en moles total de résidus d'acide dicarboxylique dans les compositions de polyester ; (ii) un composant glycol comprenant de 90 à 100 % en moles de résidus glycol par rapport au pourcentage molaire total de résidus glycol dans les compositions de polyester ; (iii) facultativement, un comonomère de ramification ; et (iv) d'environ 10 % en poids à environ 40 % en poids de poly(téréphtalate d'éthylène) recyclé (rPET). Le récipient a une hauteur de chute supérieure à 160 cm, évaluée selon ASTM D 2463-95, procédure B, méthode de l'escalier de Bruceton, après deux semaines un % de trouble inférieur à 3 %.
PCT/US2025/018539 2024-03-06 2025-03-05 Composition de polyester pour récipients moulés par extrusion-soufflage contenant un polyester post-consommation et son procédé de préparation Pending WO2025188873A1 (fr)

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