Package

Abstract

The present invention relates to a blend comprising a polyester, such as polyethylene terephthalate (PET), and a second polymer wherein the blend has two glass transition temperatures (Tg), one representing a polyester and the second Tg representing the second polymer. The second polymer is preferably suitable for transesterification with the polyester. The blends can be used to produce bottles that are bright white (e.g., high L *) and / or opaque or translucent and / or have high haze. Preferred embodiments are directed to facilitate recovery of such containers with a main recovery stream to produce high quality recovered PET (rPET).

Description

Technical Field

[0001] The present invention relates to packaging and its materials. Preferred embodiments relate to containers, such as PET bottles, which are bright white (e.g., high L*) and / or opaque or translucent and / or have high haze. Such containers can be used for household / personal care products that require some opacity. Preferred embodiments aim to facilitate the co-recycling of such containers with the main recycling stream to produce high-quality recycled PET (rPET). Background Art

[0002] The plastic packaging industry has long utilized inorganic particles such as titanium dioxide or calcium carbonate in PET to produce packaging with opacity, light-shielding properties, and different colors, especially white, pastel, and so-called "colored opaque" packaging. More recently, polymers and other organic materials have also been used in PET packaging to produce opacity, light-shielding properties, and whiteness. In these cases, it may be necessary to subject the plastic to secondary stretching to produce opacity / whiteness. Typically, the polymers and organic materials used are incompatible with PET. For example, WO2019117725A1 and WO2020106156A1 relate to a single-layer plastic container with light-shielding properties, where polymethylpentene and cycloolefin copolymer are added to the main PET plastic substrate together with an inorganic shielding filler including TiO 2 respectively.

[0003] Other plastic containers that solve the same problem of protecting their contents (such as UHT long-life milk) from light radiation have different plastic media and different types of structures, such as: three-layer polyethylene, three-layer PET, two-layer PET, or single-layer PET.

[0004] A problem associated with current methods is that PET packaging (bottles, jars, trays, cups, or films, etc.) made of known materials cannot be recycled with the main PET recycling stream of transparent colorless or colored packaging to produce transparent, high-value recycled PET (rPET) for manufacturing new PET packaging. Adding opaque / white PET packaging to the transparent recycling stream in any proportion will result in a certain degree of haze or whiteness, which is not desirable in rPET if used for manufacturing new packaging (bottles, etc.). This means that currently, opaque or white PET packaging is destined for low-value applications such as strapping tapes, building materials, fibers, and insulation materials after recycling. Summary of the Invention

[0005] The object of the present invention is to solve the above problems.

[0006] The aim of the preferred embodiment of the present invention is to produce packaging articles (such as bottles, jars, trays, cups or films) that are brightly white, opaque or translucent and / or have a high haze, and can be recycled together with the main PET recycling stream of transparent colorless or colored packaging.

[0007] According to a first aspect of the present invention, there is provided a blend comprising a polyester, such as polyethylene terephthalate (PET), and a second polymer, wherein suitably, the blend has two glass transition temperatures (Tg).

[0008] The blend is suitably arranged for producing packaging articles (such as bottles, jars, trays, cups or films) with increased opacity, and the opacity can be reduced after using the packaging articles to facilitate the recycling of the packaging articles with the main PET recycling stream.

[0009] Suitably, one Tg represents the polyester and the second Tg represents the second polymer.

[0010] Unless otherwise specified, the glass transition temperature (Tg) can be evaluated by DSC and / or as described in ASTM E1356. Unless otherwise specified, the Tg referred to herein is the midpoint of the transition region.

[0011] The Tg of the polyester is at least 70 °C, preferably at least 75 °C. The Tg of the polyester can be lower than 90 °C or lower than 85 °C.

[0012] The Tg of the second polymer can be at least 100 °C. The Tg of the second polymer can be in the range of 100 °C to 200 °C, for example in the range of 100 °C to 150 °C.

[0013] Suitably, the blend has a Tg corresponding to the polyester. Therefore, the Tg of the blend can be at least 70 °C. The Tg of the blend can be at least 75 °C. The Tg of the blend can be lower than 90 °C or lower than 85 °C.

[0014] Suitably, the blend has a second Tg, for example at least partly due to the Tg formed by the inclusion of the second polymer in the blend. Suitably, the second Tg of the blend is at least 100 °C, for example in the range of 100 °C to 200 °C or in the region of 100 °C to 150 °C. Suitably, the second polymer is incompatible with the polyester, which means that the polyester and the second polymer have a certain degree of immiscibility, which in turn means that the blend has the two Tgs described.

[0015] The difference in Tg between the polyester and the second polymer can be at least 10 °C, preferably at least 15 °C, more preferably at least 20 °C. The difference in Tg between the polyester and the second polymer can be less than 130 °C or less than 100 °C or less than 75 °C.

[0016] The blend can comprise one or more additional polymers. For example, it can comprise a third polymer that may be incompatible with the polyester. If a third polymer is included, it can be substantially compatible with the second polymer, which may mean that a blend of the second polymer and the third polymer exhibits a single Tg and / or the blend of the first aspect exhibits a single Tg due to the polyester and a second Tg due to the presence of the second polymer and / or the third polymer.

[0017] Thus, suitably, the blend comprises a first Tg formed due to the presence of the polyester and a second Tg exhibited due to the presence of the second polymer and / or the third polymer.

[0018] When the blend comprises the polyester and the only polymer in the blend that is incompatible with the polyester is the second polymer, the blend can have a Tg corresponding to that of the second polymer. The Tg can be at least 100 °C, for example in the range of 100 °C to 200 °C or in the range of 100 °C to 150 °C.

[0019] The polyester and the second polymer of the first aspect are preferably such that when tested as described, a 1:1 weight blend of the polyester and the second polymer exhibits at least two glass transition temperatures (Tg) as described above.

[0020] When the blend is subjected to a heat orientation step, the presence of two Tgs can confirm the incompatibility of the polymers in the blend. In this case, preferably, the Tg of the second polymer is at least 20 °C - 30 °C higher than the Tg of the polyester.

[0021] In addition, the refractive index can be used to select the second polymer. The opacity can be increased by increasing the absolute value of the difference in refractive index between the polyester and the second polymer. The refractive indices can differ by at least 0.02 in absolute value.

[0022] The polyester of the first aspect and the second polymer are preferably such that when the polyester and the second polymer are blended at a weight ratio of 1:1 to form a sample as described in Example 16, when evaluated as described in Tests 3 and 2 respectively, for light with a wavelength of 550 nm, the transmittance of the sample through the 3 mm area of the sample is less than 70% (preferably less than 60% or less than 50%) and / or the haze % is greater than 20%. Suitably, the sample is made by injection molding on a Boy 22A injection molding machine having a barrel with a diameter of 75 mm and a screw with a diameter of 24 mm. The program of this machine sets the barrel temperature to achieve a melt temperature of 295 °C, the polymer residence time is 90 - 120 seconds, and the screw speed during the plasticizing part of the injection molding process is between 150 - 350 rpm.

[0023] The polyester and the second polymer preferably have a "robustness ratio" (R) of the blend less than 1.15, preferably less than 1.10, where:

[0024]

[0025] where: (I) Specimen A is prepared in a method including the following steps: Select a blend containing 88 wt% of the polyester and 12 wt% of the second polymer; and injection mold the blend at 295 °C to produce a standard sample, where the injection molding is suitably carried out on a Boy 22A injection molding machine having a barrel with a diameter of 75 mm and a screw with a diameter of 24 mm. The program of this machine sets the barrel temperature to achieve a melt temperature of 295 °C, a polymer residence time of 90 - 120 seconds, and the screw speed during the plasticizing part of the injection molding process is between 150 - 350 rpm, and

[0026] where: (II) Specimen B is made as described for Specimen A, but at a temperature of 310 °C instead of 295 °C.

[0027] The polyester of the first aspect and the second polymer are preferably such that when a 1:1 weight ratio blend of the polyester and the second polymer is granulated together with 600 ppm of titanium metal introduced using a n-butanol solution of 90% titanium butoxide (the titanium metal suitably acts as a transesterification catalyst), the particles exhibit a single glass transition temperature (Tg).

[0028] The second polymer is preferably suitable for transesterification with the polyester.

[0029] As described above, the blend may optionally contain a third polymer. The third polymer may have any characteristics of the second polymer (but is suitably different from the second polymer). The third polymer may be substantially incompatible with the polyester in the blend. The third polymer is preferably suitable for transesterification with the polyester.

[0030] The second polymer is preferably incompatible with PET (e.g., as shown by the blend having two Tgs), preferably incompatible with PET prepared from PTA and MEG, such as Lighter TM C93 PET copolymer.

[0031] The second polymer preferably comprises one or more repeating units that result in its incompatibility as described above. In a first embodiment, the second polymer may comprise repeating units that do not contain an aromatic moiety, such as repeating units that do not contain a cyclic or polycyclic aromatic moiety. Preferably, the second polymer comprises repeating units that do not contain a phenyl or naphthyl moiety. In the first embodiment, the second polymer may comprise repeating units that contain a combination of an ester moiety and a saturated hydrocarbon moiety. In such a case, the second polymer may comprise lactic acid repeating units. The second polymer may be polylactic acid.

[0032] In a second embodiment, the second polymer may comprise repeating units that result in its incompatibility with PET. The repeating units may comprise a cyclic moiety, such as a saturated cyclic moiety. Such a cyclic moiety may be relatively large and may result in the incompatibility of the second polymer and the PET. The cyclic moiety may contain only carbon atoms and hydrogen atoms, or may be a heterocyclic moiety. The cyclic moiety may be an optionally substituted four- to six-membered cyclic moiety. The cyclic moiety preferably comprises only carbon atoms and hydrogen atoms. In the second embodiment, the second polymer may comprise repeating units that include an ester moiety. The second polymer may be a copolyester. It may comprise repeating units derived from a diol that incorporates the cyclic moiety. Such a diol may be selected from:

[0033] and

[0034]

[0035] In a preferred embodiment, the copolyester comprises repeating units derived from I and II.

[0036] The copolymer may be prepared by reacting diol I and / or II with a dicarboxylic acid (or dicarboxylic acid derivative), where dimethyl terephthalate is a preferred example. Tritan TM copolyester described herein is preferred.

[0037] In a third embodiment, the second polymer may be a polycarbonate. The polycarbonate may comprise repeating units that result in its incompatibility with the PET. The repeating units may comprise a cyclic moiety, particularly a heterocyclic moiety; preferably an unsaturated cyclic moiety, particularly an unsaturated heterocyclic moiety.

[0038] The cyclic moiety can be a fused cyclic moiety, can be relatively large, and can render the second polymer incompatible with the PET. In a preferred embodiment, the polycarbonate can incorporate isosorbide-derived repeating units and / or can be prepared using isosorbide monomer.

[0039] When a third polymer is included as described above, the third polymer preferably comprises one or more repeating units that render it incompatible as described above. In a first instance, the third polymer can include repeating units that do not contain an aromatic moiety (e.g., no cyclic or polycyclic aromatic moiety). Preferably, the third polymer includes repeating units that do not contain a phenyl or naphthyl moiety. In the first embodiment, the third polymer can include repeating units that include a combination of an ester moiety and a saturated hydrocarbon moiety. In such a case, the third polymer can include lactic acid repeating units. The third polymer can be polylactic acid.

[0040] In a second embodiment, the third polymer can include repeating units that render it incompatible with the PET. The repeating units can include a cyclic moiety, such as a saturated cyclic moiety. Such a cyclic moiety can be relatively large and can result in incompatibility between the third polymer and the PET. The cyclic moiety can contain only carbon and hydrogen atoms or can be a heterocyclic moiety. The cyclic moiety can be an optionally substituted four- to six-membered cyclic moiety. The cyclic moiety preferably includes only carbon and hydrogen atoms. In the second embodiment, the third polymer can include repeating units that include an ester moiety. The third polymer can be a copolyester. It can include repeating units derived from a diol that incorporates the cyclic moiety. Such a diol can be selected from the diols of formula I and / or II as described above.

[0041] In a third embodiment, the third polymer can be a polycarbonate. The polycarbonate can include repeating units that render it incompatible with the PET. The repeating units can include a cyclic moiety, particularly a heterocyclic moiety; preferably an unsaturated cyclic moiety, particularly an unsaturated heterocyclic moiety.

[0042] The cyclic moiety can be a fused cyclic moiety, can be relatively large, and can render the third polymer incompatible with the PET. In a preferred embodiment, the polycarbonate can contain isosorbide-derived repeating units and / or can be prepared using isosorbide monomer.

[0043] The blend can be a masterbatch, such as a solid masterbatch, preferably in the form of pellets or granules.

[0044] The blend (herein "masterbatch blend") can comprise less than 20% by weight, preferably less than 10% by weight, of a combination of the polyester with the second polymer and optional third polymer as described above. The total weight percentage of the second polymer and the third polymer in the masterbatch blend can be at least 80% by weight, preferably at least 90% by weight. This total is preferably less than 99% by weight or less than 95% by weight. Preferably, the masterbatch blend comprises at least 80% by weight, more preferably at least 90% by weight, of the first polymer.

[0045] The masterbatch blend can comprise:

[0046] 1 to 20% by weight, preferably 3 to 10% by weight, of the polyester;

[0047] 45 to 99% by weight, preferably 90 to 97% by weight, of the second polymer; and

[0048] 0 to 45% by weight, preferably 0 to 7% by weight, of the third polymer.

[0049] As an alternative to the masterbatch blend, the blend can be a packaging blend, suitably a blend for packaging materials (such as bottles, jars, trays, cups or films). In a preferred embodiment, the container is a container preform or a container such as a bottle. The packaging blend can be formed in a melt processing apparatus and / or can define at least a portion (preferably substantially all, suitably excluding any closures) of a packaging article (such as a preform or a container such as a bottle), which can be made, for example, by placing the masterbatch mixture into additional polyester to define the packaging blend.

[0050] The packaging blend can comprise at least 0.5% by weight, preferably at least 1.0% by weight, more preferably at least 2.0% by weight, of the second polymer. The packaging blend can comprise less than 20% by weight, preferably less than 15% by weight, more preferably less than 10% by weight, of the second polymer.

[0051] The packaging blend can comprise at least 50% by weight, preferably at least 65% by weight, more preferably at least 80% by weight, of polyester, preferably a single type of polyester, which is preferably polyethylene terephthalate (PET). The packaging blend can comprise less than 99% by weight, preferably less than 96% by weight, of the polyester.

[0052] In the packaging blend, the sum of the weight percentages of the polyester (such as PET), the second polymer and the optional third polymer is preferably at least 95% by weight, preferably at least 98% by weight.

[0053] In the packaging blend, the ratio defined as the weight percentage of the polyester (e.g., PET) divided by the sum of the weight percentages of the second polymer and the optional third polymer can be at least 5, for example in the range of 5 to 25.

[0054] The blend can be a packaging blend in the form of a packaging article (e.g., a bottle, a jar, a tray, a cup, or a film). In a preferred embodiment, the packaging article is, for example, a preform or a container (such as a bottle). The preform or the container (suitably excluding any closures) can consist essentially of the packaging blend.

[0055] The polyester of the first aspect, for example in the masterbatch blend or the packaging blend, is preferably polyethylene terephthalate, and in the context of this specification, the term can include copolyethylene terephthalate. The copolyethylene terephthalate of polyethylene terephthalate can contain at least 85 mol% (e.g., at least 92 mol%, or at least 97 mol%) of terephthalic acid (or terephthalic acid derivatives) and at least 85 mol% (e.g., at least 92 mol%, or at least 97 mol%) of ethylene glycol repeating units. In a preferred embodiment, the polyethylene terephthalate has less than 10 mol%, more preferably less than 6 mol%, and particularly less than 2 mol% of comonomer substitution. Preferably, the polyethylene terephthalate essentially comprises a homopolymer prepared by esterification or transesterification of terephthalic acid or dimethyl terephthalate with ethylene glycol. The monomers can be subjected to a polycondensation reaction at a high temperature in a vacuum in the presence of a catalyst.

[0056] The term "IV" as used herein refers to the intrinsic viscosity of a polymeric material. It can be measured in a solution of dissolving 0.5 grams of the polymer in 100 milliliters of a mixture of phenol (60 volume%) and tetrachloroethane (40 volume%). The IV of the polyester in the blend is preferably greater than 0.5 dL / g, more preferably greater than 0.65 dL / g. It can be less than 0.80 dL / g.

[0057] Suitably, the container preform as described herein is a test tube-shaped article, which can be prepared by injection molding and is suitably arranged for stretch blow molding to define a bottle.

[0058] According to a second aspect, there is provided a packaging article comprising the packaging blend according to the first aspect. At least 90 wt%, preferably at least 95 wt%, more preferably at least 99 wt% of the layers of the packaging article can be constituted by the packaging blend. The packaging article preferably includes only one layer. The packaging article is preferably a single-layer container.

[0059] The packaging article is preferably in the form of a single-layer preform or container (such as a bottle) that contains the packaging blend and is preferably composed essentially of the packaging blend. At least 90% by weight, preferably at least 95% by weight, more preferably at least 99% by weight of the single-layer preform or container can be constituted by the packaging blend. For example, the single layer of the preform or container (such as a bottle) can comprise:

[0060] 2 to 20% by weight, preferably 4 to 15% by weight of the second polymer;

[0061] 0 to 20% by weight, preferably 0% by weight of the third polymer; and

[0062] more than 80 wt% or more than 85 wt% of a polyester (preferably PET), which is suitably different from the second polymer and the optional third polymer.

[0063] The packaging article can include an identification device so as to be able to identify the packaging article as described herein and / or be arranged for treatment, thereby reducing the opacity of the composition constituting the packaging article, for example to facilitate the recycling of the packaging article with the main PET recycling stream. The identification device can be an identifier (such as a code) marked on the packaging article, for example which is not visible to the naked eye, or it can include an additive, the presence of which can be identified by optical or other means. The identification device can be arranged to be identified by a spectroscopic device (such as by near-infrared radiation).

[0064] According to a third aspect of the present invention, there is provided a method for producing a packaging article, the method comprising melt-processing a polyester and a second polymer to produce a blend, wherein suitably the blend has two glass transition temperatures (Tg).

[0065] The method can include melt-processing the blend according to the first aspect.

[0066] The packaging article can be as described according to the second aspect.

[0067] The method can include:

[0068] (i) selecting a blend according to the first aspect, optionally contacting the blend with one or more other polymers, such as with an additional polyester, preferably PET, for example to define a packaging blend according to the first aspect; and melt-processing the blend to produce a packaging article (such as a preform for a container such as a bottle); or

[0069] (ii) Select a second polymer according to the first aspect (and optionally a third polymer according to the first aspect), and bring the second polymer (and optionally the third polymer) into contact with the polyester (such as PET); and melt process the second polymer, the optional third polymer, and the polyester (such as PET) to produce a packaging article (such as a preform for a container such as a bottle).

[0070] The method may include stretch blow molding the preform to produce a packaging article in the form of a container (such as a bottle).

[0071] The method may include associating an identification device according to the first aspect with the packaging article.

[0072] The method of the third aspect is preferably a method of increasing the opacity of a container (such as a bottle, for example a polyester (such as PET) bottle). The method may include producing a container with increased opacity, for example having increased opacity compared to other identical containers that do not contain the second polymer and / or that consist only of the polyester (such as PET).

[0073] Advantageously, the blend can be used to produce packaging articles (such as bottles, jars, trays, cups or films) with increased opacity, and after use of the packaging article (such as a bottle, jar, tray, cup or film), the opacity can be reduced to facilitate the recycling of the packaging article (such as a bottle, jar, tray, cup or film). Preferably, by reducing the opacity, the packaging article can be recycled with the main PET recycling stream and / or recycled to produce transparent, high-value recycled PET (rPET). In one embodiment, a plurality of packaging articles (such as bottles) containing the blend can be selected and processed together (such as by transesterification) to reduce the opacity. Then, the transesterified material can be mixed with the main recycling stream (such as containing virgin PET or other PET) to produce rPET. In another embodiment, a packaging article (such as a bottle) containing the blend can be selected and processed, for example with a transesterification catalyst, together with the main recycling stream (such as containing virgin PET or other PET) to effect transesterification and produce transparent, high-value recycled PET (rPET).

[0074] Preferably, the packaging article (such as a container) of the third aspect has a transmittance at 400 nm of less than 75%, such as less than 70%, suitably determined as described in Test 3. The packaging article can be arranged such that the second polymer can transesterify with the polyester (such as PET) to produce a material that, if melt processed to produce another packaging article (such as a bottle) with the same wall thickness, has a transmittance at 400 nm that is higher (such as at least 5% or at least 10%) than the transmittance of the packaging article (such as a container) from which the material is derived.

[0075] In a fourth aspect, the invention extends to a method of recycling a packaging article (such as a bottle, can, tray, cup or film, in particular a PET bottle), as described in any of the foregoing aspects, the method comprising selecting a packaging article that comprises a polyester, a second polymer and optionally a third polymer, and treating the packaging article to reduce opacity and / or effect transesterification of the second polymer with the polyester.

[0076] The method may comprise:

[0077] (i) selecting a packaging article that comprises a polyester, a second polymer and optionally a third polymer as described in any of the foregoing aspects, wherein the packaging article has a transmittance at 400 nm of less than 75%, less than 70%, less than 60% or less than 50%, the transmittance being measured, for example, on a cut portion of the wall of the packaging article as described in Test 3; and

[0078] (ii) treating the packaging article to reduce opacity and / or effect transesterification. After treatment, a blend may be prepared which, when molded into a specimen having a thickness comparable to that of the cut portion of the wall, has a transmittance at 400 nm greater than that of the cut portion. The difference in transmittance at 400 nm between the cut portion and the specimen may be at least 10%, at least 20%, at least 30% or at least 40%.

[0079] The treatment method may comprise using a transesterification catalyst to facilitate transesterification.

[0080] The method of the fourth aspect may comprise determining whether the packaging article comprises an identification device (such as the identification device as described in the first aspect) to confirm that the packaging article is as described herein and / or is arranged to be treated (such as to effect transesterification), whereby the opacity of the composition constituting the packaging article may be reduced. Suitably, therefore, the method comprises selecting a packaging article that comprises the identification device as described in the first aspect. The method may comprise selecting a plurality (such as at least 10 or at least 50) of packaging articles that comprise the identification device as described in the first aspect and treating the plurality of packaging articles as described in step (ii).

[0081] The method of the fourth aspect may comprise mixing the packaging article selected in step (i) or treated as described in step (ii) with additional polyester (such as PET). The additional polyester (such as PET) may comprise virgin polyester (such as polyester) or polyester (such as PET) derived from a packaging article (such as a container) and has a higher transmittance at 400 nm compared to the comparable light transmittance of the packaging article selected in step (i).

[0082] In the method of the fourth aspect, pellets or granules of recycled PET (rPET) can be produced. The pellets or granules are preferably such that, for example when evaluated as described in Test 3, the light transmittance at 400 nm of an injection molded specimen having the same thickness as the packaging article selected in step (i) is greater than (e.g., at least 10% or at least 20%) the light transmittance of the packaging article selected in step (i).

[0083] According to a fifth aspect, there is provided the use of a second polymer (and optionally a third polymer) as described in any of the foregoing aspects for increasing the opacity of a polyester (e.g., PET) in a packaging article (such as a bottle, can, tray, cup or film), wherein the opacity can preferably be reduced by a transesterification reaction involving the second polymer (and optionally the third polymer) (suitably to facilitate the recycling of the polyester (e.g., PET)). Accordingly, the present invention extends to the use of the second polymer (and optionally the third polymer) to increase the opacity as described above and improve the recyclability of a packaging article (such as a bottle, bottle, tray, cup or film).

[0084] In a sixth aspect, the present invention extends to recycled PET (rPET), such as recycled PET obtained by the method of the fourth aspect, and / or recycled PET comprising a blend of a polyester and a second polymer as described herein, wherein the blend has been treated to transesterify the second polymer. The rPET can comprise the blend and additional PET, and the additional PET can comprise PET from a source other than the blend and / or can include virgin PET.

[0085] Any aspect of any invention described herein can be combined with other aspects of any invention described herein, with appropriate modifications if necessary. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Specific embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0087] Figure 1 shows the light transmittance of the bottle wall of a bottle containing the blend as described in Examples 4 to 12;

[0088] Figure 2 shows the DSC analysis of the blends of Examples 13 and 14;

[0089] Figure 3 shows a graph of the light transmittance vs. wavelength of specimens of Examples 13, 14 and pure PET-X;

[0090] Figure 4 shows the average haze of specimens of Examples 13, 14 and pure PET-X;

[0091] Figure 5 Shows the relationship between the light transmittance and wavelength of the bottles of Example 18a, 18b and pure PET-X; and

[0092] Figure 6 Includes the relationship between the light transmittance and wavelength of the bottles of Examples 19 to 23. Detailed Description

[0093] The following materials are mentioned below:

[0094] PET-X - Refers to a proprietary bottle-grade PET (Lightweight C93 from Equippolymers, intrinsic viscosity (IV) of 0.80 + / - 0.02), refractive index n 1.575.

[0095] Natureworks 4043D (polylactic acid) - A general polylactic acid grade, MFR of 6 (210 °C / 2.16 kg), glass transition temperature of 55 °C - 60 °C, melting point temperature of 145 °C. Refractive index n 1.465.

[0096] Tritan TX1001 (PET copolyester) - An amorphous copolyester proprietary to Eastman, composed of the dibasic acid terephthalic acid and the diols ethylene glycol, 1,4-cyclohexanedimethanol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The glass transition temperature of the copolyester is 110 °C. Refractive index n 1.54.

[0097] Tritan TX2001 (PET copolyester) - An amorphous copolyester proprietary to Eastman, composed of the dibasic acid terephthalic acid and the diols ethylene glycol, 1,4-cyclohexanedimethanol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. The glass transition temperature of the copolyester is 120 °C. Refractive index n 1.54.

[0098] Natureworks 4043D / Tritan TX1001 - A mixture of Natureworks 4043D and Tritan TX1001 in a weight ratio of 1:1. This can be a melt-blended and pelletized mixture or a physical mixture of two polymer resin pellets.

[0099] Verbatim Durabio 3D printing polymer (isosorbide polycarbonate) - A proprietary polycarbonate from Mitsubishi Chemical based on isosorbide and containing no bisphenol A (BPA). Its melting temperature is 235 °C.

[0100] Generally, in a preferred embodiment, PET is melt blended with a second polymer in a twin-screw extruder, and the second polymer can be a polyester or polycarbonate that is relatively incompatible with PET to produce a partially or completely opaque white compound. This compound can be processed using standard techniques (such as injection molding) to make a partially or completely opaque white article. The opacity / whiteness can be further enhanced by biaxial orientation and stretching of the article, which occurs, for example, in the injection stretch blow molding process commonly used to manufacture PET bottles. In a preferred embodiment, when needed, the polyester blend and the articles made therefrom can be subjected to a further processing step where the blend (e.g., in a twin-screw extruder) is remelted and the polyester blend undergoes an ester exchange reaction in the molten phase, preferably with the addition of a suitable ester exchange catalyst (such as titanium(IV) alkoxide). In a preferred embodiment, during melt processing (such as injection molding), the ester exchange reaction is minimized to produce articles (such as bottles), thereby optimizing the incompatibility between PET and the second polymer and the resulting opacity / whiteness; but during the production of rPET from PET recycling, the ester exchange reaction is optimized and / or promoted.

[0101] This document relates to the following tests:

[0102] Test 1 - L*a*b* color space evaluation of blow molded bottles and specimens

[0103] For bottles, first, a small (60 mm × 60 mm) square portion is cut from the bottle wall. This portion is placed on the holder of a Minolta CM3600A spectrophotometer, with the outer surface of the bottle portion facing the instrument aperture. For specimens, the area of interest is placed on the holder of a Minolta CM3600A spectrophotometer. The large area view (LAV) aperture is used, and the color of the sample is measured in transmission mode using a D65 light source. The L*, a*, and b* values are recorded.

[0104] Test 2 - Haze measurement in specimens according to ASTM D1003

[0105] The specimen is placed in the path between a D65 light source and the detector of a Minolta CM3600A spectrophotometer and measured against reference white and black backgrounds. The spectrophotometer uses these measurements to calculate the haze percentage of the sample. Compared with the reference measurement where the reference sample is air (i.e., no specimen), the lower the haze percentage, the higher the transparency.

[0106] Test 3 - Transmittance measurement of blow molded bottles or specimens

[0107] The transmittance of each bottle is evaluated on the cut portion of the bottle wall in the wavelength range of 300 nm - 700 nm using a Shimadzu ultraviolet-visible spectrophotometer with an integrating sphere. Specimens can be evaluated in a similar manner.

[0108] Example 1 - General procedure for preform manufacture

[0109] The preforms are manufactured on a Husky GL160 injection molding machine equipped with a double cavity mold. PET-X and the second polymer are manually premixed and added to a hopper installed above the feed inlet of the injection molding machine. Standard PET injection molding processes are used to produce the preforms.

[0110] Example 2 - Production of bottles from preforms

[0111] A Sidel SB01 blow molding machine is used to stretch blow the preforms into 1-liter cylindrical bottles. Standard blowing processes are employed. Before the preforms leave the oven and enter the blow mold, the total power percentage of the heating furnace is adjusted to bring the preform temperature to 115°C - 120°C. This is referred to as the blow temperature.

[0112] Examples 3 to 12 - Production of bottles with compounds

[0113] Following the procedure of Example 1, preforms are produced by mixing PET-X and the specified second polymer material at the specified let-down ratio, as shown in the following table.

[0114]

[0115] As described in Example 2, bottles are blown from the preforms and the light transmittance of the bottles is evaluated as described in Test 3. Figure 1 Results are provided normalized to a cross-sectional thickness of 330 μm. In this regard, since the wall thickness of the samples does not vary significantly from the nominal thickness of 330 μm, normalization involves multiplying the measured transmittance percentage by the nominal thickness divided by the actual thickness. Figure 1 It is shown that adding the specified polymer to PET-X reduces the transmittance. Compared to bottles containing 100% PET-X, the bottles generally appear opaque.

[0116] Example 13 - Preparation of PET-X and Tritan TX1001 blend

[0117] A blend of PET-X and Tritan TX1001 in a weight ratio of 1:1 is mixed and pelletized in a twin-screw extruder.

[0118] The extrudate made from the pellets has a milky, translucent appearance and exhibits high viscoelasticity in the molten state. The extrudate is pelletized.

[0119] Example 14 - Preparation of blend of PET-X, Tritan TX1001 and transesterification catalyst

[0120] A 1:1 (weight ratio) blend of PET-X and Tritan TX1001 was mixed in a twin-screw extruder. A 90% n-butanol solution of titanium butoxide with 0.427 wt% LDR was added as a transesterification catalyst at the feed port of the twin-screw extruder (equivalent to adding 600 ppm of titanium metal). Transparent extrudates were produced and pelletized.

[0121] Example 15 - Comparison of DSC profiles of blends of Examples 13 and 14

[0122] DSC analysis was performed on the blends of Examples 13 and 14, and the results are as Figure 2 shown. The blend of Example 13 showed two glass transitions, indicating the immiscibility of the physical blend of the two polymers. The blend of Example 14 showed a single glass transition temperature and no melting or crystallization peaks, indicating the formation of an amorphous copolyester.

[0123] Example 16 - Comparison of specimens made from blends of Examples 13 and 14

[0124] The crystalline and dried pellets of the blend of Example 13 were injection-molded to prepare stepped specimens with thicknesses of 2 mm and 3 mm (steps). Unless otherwise stated, the measurements were made through a 3-mm thickness. The specimens were found to show a significant degree of opacity.

[0125] The dried pellets of the blend of Example 14 were injection-molded into stepped specimens with a thickness of 3 mm. The transparency of the specimens was found to be comparable to that of specimens made of pure PET-X.

[0126] The specimens were evaluated as described in Test 1, and the specimen data are shown in the following table. The values are the average of ten measurements.

[0127]

[0128] Figure 3 Transmission data for Examples 13, 14, and pure PET-X were provided. The average haze of the specimens of Examples 13, 14, and pure PET-X was evaluated as described in Test 2, as Figure 4 shown.

[0129] The results of Example 15 showed that the blend of Example 13 contained incompatible polymers, which were immiscible. This immiscibility means that the blend can be used to produce opaque bottles, as shown in Examples 9 to 12. However, when the blend contains a transesterification catalyst as described in Example 14, the blend becomes compatible, which is demonstrated by the blend having a single Tg and the blend showing a high transmittance when compared as described in Example 16. That is, the specimen containing the blend of Example 14 had an L* similar to that of pure PET-X and a low haze (<10%), while the specimen containing the blend of Example 13 had a significantly lower L* and was substantially opaque (with a measured haze of 98%).

[0130] Example 17 - Preparation of blend of PET-X, Tritan and transesterification catalyst

[0131] Following the procedure of Example 14, titanium metal equivalent to 400 ppm was used. A transparent extrudate was produced using this material.

[0132] Example 18 - Comparison of bottles made from alternative blends of PET-X and Tritan with and without transesterification catalyst and production of bottles using the blends and production of bottles using the blends

[0133] The glass transition temperature of Tritan TX2001 is 120 °C. It was mixed in PET-X at 12% LDR, and a n-butanol solution of 90% titanium butoxide (the content is equivalent to adding 1200 ppm of titanium metal) was added at the feed port. A transparent copolyester extrudate was produced, granulated, crystallized, and dried.

[0134] The produced pellets were used to manufacture 1 L bottles with a nominal wall thickness of 250 microns (referred to as Example 18a). Bottles (referred to as Example 18b) were produced using an equivalent process but without a transesterification catalyst (i.e., without titanium butoxide).

[0135] Figure 5 It was shown that the bottles made from the catalyst-free blend (Example 18b) were white and opaque (low transmittance), while the bottles made with the catalyst were substantially transparent (high transmittance) and / or had a transparency / color similar to those made from pure PET-X.

[0136] Examples 19 to 23 - Comparison of blends containing Tritan TX2001 with blends containing polyethylene naphthalate (PEN) Figure 6

[0137] Following the procedure described in Example 1, preforms containing PET-X and Tritan TX2001 or PEN were prepared. The preforms were injection molded at a temperature of 295 °C or 310 °C. The following table describes the components and conditions used to manufacture the preforms.

[0138]

[0139] As described in Example 2, the preform is blown into a bottle. Then, the transmittance of the bottle is evaluated as described in Test 3, and the results are as Figure 6 shown.

[0140] Reference ​ , the transmittance percentages of Examples 22 and 23 are substantially the same. In contrast, compared with Examples 22 and 23, the transmittance percentage of Example 20 is unfavorably higher (i.e., the opacity of the bottle is lower), indicating that the incompatibility between PEN and PET is lower compared to Tritan TX2001, and / or it is not strong enough during the injection molding production of the preform. For example, an ester exchange reaction may occur between PET / PEN during the injection molding process, increasing their compatibility, thereby increasing the transmittance and reducing the opacity.

[0141] Example 21 has a transmittance similar to that of pure PET-X of Example 19, indicating that at a higher injection molding temperature (e.g., 310 °C), PET-X and PEN undergo ester exchange and become substantially completely compatible, thereby producing a bottle with a transparency similar to that of a bottle composed of PET-X. Therefore, if PEN is used as a polymer incompatible with PET, it must be processed very carefully and / or processed at a low injection molding temperature. Even with such careful treatment (e.g., as shown in Example 20), its ability to make PET opaque is significantly lower than that of Tritan TX2001.

[0142] The inventors have summarized from the above and other experiments that the second polymer has the following advantageous properties: It can be blended with a polyester (e.g., PET) to produce a blend, which on the one hand can be used to manufacture an opaque bottle; on the other hand, it can then be processed to substantially eliminate the opacity (and / or make the transmittance of the blend reach or approach that of pure PET) so that the blend can be recycled together with substantially pure PET obtained from bottles (or other sources).

[0143] The advantageous properties include the following:

[0144] (i) The second polymer is a polyester or polycarbonate polymer or copolymer.

[0145] (ii) When 50 wt% of standard PET (e.g., PET-X) and 50 wt% of the selected second polymer are blended and extruded to produce uniform pellets, when tested using DSC, the pellets exhibit at least two glass transition temperatures (Tg).

[0146] (iii) As described in Example 16, when a specimen is prepared using a 1:1 weight ratio blend of standard PET and the selected second polymer, when evaluated as described in Tests 3 and 2 respectively, the transmittance of the specimen for light with a wavelength of 550 nm is less than 70% and / or the haze percentage is greater than 20%.

[0147] (iv) When tested as described above, the "robustness ratio" (R) of the second polymer is less than 1.10.

[0148] Wherein:

[0149]

[0150] Wherein: Specimen A is prepared by a method comprising the steps of: selecting a blend comprising 88% by weight of said polyester and 12% by weight of a second polymer; and injection molding the blend at 295 °C to produce a standard specimen, wherein the injection molding is suitably carried out on a Boy 22A injection molding machine having a barrel diameter of 75 mm and a screw diameter of 24 mm, the program of the machine setting the barrel temperature to achieve a melt temperature of 295 °C, a polymer residence time of 90 - 120 seconds, and a screw speed during the plasticizing part of the injection molding process between 150 - 350 rpm; and

[0151] Wherein: Specimen B is prepared as described for Specimen A, but at a temperature of 310 °C instead of 295 °C.

[0152] The present invention is not limited to the details of the above embodiments. The present invention extends to any novel feature or any combination of novel features disclosed in the features of this specification (including any accompanying claims, abstract, and drawings), or to any innovative step or any combination of innovative steps in the steps of any method or process disclosed.

Claims

1. A blend comprising a polyester, such as polyethylene terephthalate (PET); and a second polymer, wherein the blend has two glass transition temperatures (Tg).

2. The blend according to claim 1, wherein the blend is configured for producing a packaging article with increased opacity, and wherein the opacity can be reduced after using the packaging article to facilitate the recycling of the packaging article into the main PET recycling stream.

3. The blend according to claim 1 or 2, wherein the Tg of the polyester is at least 70 °C and less than 90 °C; and the Tg of the second polymer is at least 100 °C, such as 100 °C to 150 °C.

4. The blend according to any one of the preceding claims, wherein the blend has one Tg corresponding to the polyester and a second Tg formed at least in part due to the inclusion of the second polymer in the blend, wherein, preferably, the second polymer is incompatible with the polyester and / or the polyester and the second polymer have a degree of immiscibility.

5. The blend according to any one of the preceding claims, wherein the difference in Tg between the polyester and the second polymer is at least 10 °C, preferably at least 20 °C; and / or the difference in Tg between the polyester and the second polymer is less than 130 °C or less than 75 °C.

6. The blend according to any one of the preceding claims, wherein the blend optionally includes a third polymer that is incompatible with the polyester and / or is substantially compatible with the second polymer.

7. The blend according to any one of the preceding claims, wherein the polyester and the second polymer are such that when a blend having a weight ratio of the polyester to the second polymer of 1:1 is made into a specimen as described in Example 16, and suitably when evaluated as described in Tests 3 and 2 respectively, for light with a wavelength of 550 nm, the transmittance of the specimen through a 3 mm region of the specimen is less than 70%, preferably less than 60% or less than 50%, and / or the haze is greater than 20%.

8. The blend according to any one of the preceding claims, wherein the polyester and the second polymer are such that when tested as described herein, the "robustness ratio" (R) of their blend is less than 1.15, preferably less than 1.10, wherein: wherein: (I) Specimen A is prepared in a method comprising the steps of: selecting a blend comprising 88 wt% of the polyester and 12 wt% of the second polymer; and injection molding the blend at 295 °C to produce a standard specimen, wherein the injection molding is suitably carried out on a Boy 22A injection molding machine having a barrel with a diameter of 75 mm and a screw with a diameter of 24 mm, and the program of the machine sets the barrel temperature to achieve a melt temperature of 295 °C, a polymer residence time of 90 - 120 seconds, and a screw speed during the plasticizing part of the injection molding process between 150 - 350 rpm; and wherein: (II) Specimen B is prepared as described for Specimen A, but at a temperature of 310 °C instead of 295 °C.

9. The blend according to any one of the preceding claims, wherein the polyester and the second polymer are such that when a blend of the polyester and the second polymer in a weight ratio of 1:1 is granulated together with 600 ppm of titanium metal introduced using a n-butanol solution of 90% titanium butoxide (the titanium metal suitably acting as a transesterification catalyst), the granules exhibit a single glass transition temperature (Tg).

10. The blend according to any one of the preceding claims, wherein the second polymer is suitable for transesterifying with the polyester.

11. The blend according to any one of the preceding claims, wherein: (i) the second polymer comprises repeating units that do not contain an aromatic moiety, such as repeating units that do not contain a cyclic or polycyclic aromatic moiety; wherein, optionally, the second polymer includes repeating units that contain a combination of an ester moiety and a saturated hydrocarbon moiety; or (ii) the second polymer comprises repeating units that contain a cyclic moiety, such as a saturated cyclic moiety, wherein, optionally, the cyclic moiety contains only carbon atoms and hydrogen atoms or the cyclic moiety is a heterocyclic moiety; or (iii) the second polymer is a polycarbonate.

12. The blend according to claim 11, wherein, when the second polymer is as described in (i), the second polymer comprises lactic acid repeating units, such as the second polymer is polylactic acid; and when the second polymer is as described in (ii), the cyclic moiety is an optionally substituted four- to six-membered cyclic moiety; or the second polymer is a copolyester that includes repeating units derived from a diol selected from: and when the second polymer is as described in (iii), the second polymer is a polycarbonate that contains a cyclic moiety, particularly a heterocyclic moiety; preferably an unsaturated cyclic moiety, particularly an unsaturated heterocyclic moiety.

13. The blend according to claim 12, wherein the second polymer is as described in (ii) and is a copolyester that contains repeating units derived from I and II.

14. The blend according to claim 12, wherein the second polymer is as described in (iii), and the polycarbonate contains isosorbide-derived repeating units and / or is prepared using isosorbide monomer.

15. The blend according to any one of the preceding claims, wherein the blend is a solid masterbatch.

16. The blend according to any one of the preceding claims, wherein the blend comprises: 1 to 20% by weight, preferably 3 to 10% by weight of the polyester; 45 to 99% by weight, preferably 90 to 97% by weight of the second polymer; and 0 to 45% by weight, preferably 0 to 7% by weight of the third polymer.

17. The blend according to any one of the preceding claims, wherein the blend is a packaging blend that contains at least 0.5% by weight, preferably at least 2.0% by weight of the second polymer; and less than 20% by weight, preferably less than 10% by weight of the second polymer; and contains at least 50% by weight, preferably at least 80% by weight of polyester.

18. The blend according to claim 16 or 17, wherein, In the packaging blend, the sum of the weight percentages of the polyester (e.g., PET), the second polymer, and optionally the third polymer is at least 95 wt%, preferably at least 98 wt%; and / or In the packaging blend, the ratio defined as the weight percentage of the polyester (e.g., PET) divided by the sum of the weight percentages of the second polymer and optionally the third polymer is at least 5, e.g., in the range of 5 to 25.

19. The blend according to any one of the preceding claims, wherein the blend is in the form of a packaging article, such as a preform or a container such as a bottle.

20. A packaging article comprising the packaging blend according to any one of the preceding claims.

21. The packaging article according to claim 20, wherein the packaging article is in the form of a single-layer preform or container (such as a bottle) comprising the packaging blend, preferably consisting essentially of the packaging blend.

22. The packaging article according to claim 21, wherein the single layer of the preform or container comprises: from 2 to 20 wt%, preferably from 4 to 15 wt% of the second polymer; from 0 to 20 wt%, preferably 0 wt% of the third polymer; and more than 80 wt% or more than 85 wt% of polyester (preferably PET).

23. The packaging article according to any one of claims 20 to 22, wherein the packaging article comprises an identification means so that it is possible to identify that the packaging article is arranged to be processed, thereby reducing the opacity of the composition constituting the packaging article, e.g., to facilitate the recycling of the packaging article into the main PET recycling stream.

24. The packaging article according to any one of claims 20 to 23, wherein the packaging article, such as a container, has a transmittance at 400 nm of less than 75%, e.g., less than 70%, and wherein the packaging article is arranged such that the second polymer can transesterify with the polyester (e.g., PET) to produce a material which, if melt processed to produce another packaging article, such as a bottle, with the same wall thickness, has a higher transmittance at 400 nm (e.g., at least 5% or at least 10% higher) than the packaging article (e.g., container) from which the material is sourced.

25. A method of producing a packaging article, such as a method of producing a packaging article according to any one of claims 20 to 24, the method comprising melt processing a polyester and a second polymer to produce a blend, wherein the blend has two glass transition temperatures (Tg).

26. The method according to claim 25, wherein the method is a method of increasing the opacity of a container (such as a bottle, e.g., a polyester (such as PET) bottle); and / or the method comprises producing a container having an increased opacity compared to other identical containers that do not contain the second polymer and / or that consist only of the polyester (e.g., PET).

27. The method according to claim 25 or 26, wherein the blend is used to produce a packaging article with increased opacity, wherein the opacity can be reduced after use of the packaging article to facilitate the recycling of the packaging article (e.g., a bottle).

28. The method according to any one of claims 25 to 27, wherein a plurality of packaging articles comprising the blend are selected and processed together to reduce opacity, for example by transesterification.

29. The method according to claims 25 to 28, wherein the blend is treated to transesterify the second polymer with the polyester.

30. A method of recycling a packaging article, such as a container (e.g., a PET bottle), the method comprising selecting a packaging article comprising a polyester, a second polymer, and optionally a third polymer as described in any one of the preceding claims; and treating the packaging article to reduce opacity and / or effect transesterification of the second polymer with the polyester.

31. The method according to claim 30, the method comprising: (i) selecting a packaging article comprising a polyester, a second polymer, and optionally a third polymer as described in any one of the preceding claims, wherein the packaging article has a transmittance at 400 nm of less than 75%, less than 70%, less than 60% or less than 50%, the transmittance being measured, for example, on a cut portion of the wall of the packaging article according to Test 3; and (ii) treating the packaging article to reduce opacity and / or effect transesterification.

32. The method according to claim 30 or 31, wherein the method comprises using a transesterification catalyst to facilitate transesterification.

33. The method according to any one of claims 30 to 32, wherein the method comprises selecting a packaging article comprising an identification means so as to be able to identify that the packaging article is arranged to be treated so that the opacity of the composition constituting the packaging article can be reduced, for example to facilitate the recycling of the packaging article into the main PET recycling stream.

34. The method according to any one of claims 31 to 33, the method comprising blending the packaging article selected in step (i) or the packaging article treated as described in step (ii) with additional polyester (e.g., PET).

35. Use of the second polymer (and optionally the third polymer) as described in any one of the preceding claims for increasing the opacity of a polyester (e.g., PET) in a packaging article (such as a bottle), wherein the opacity can be reduced by a transesterification reaction involving the second polymer (and optionally the third polymer).

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