Package

Abstract

The present invention relates to a blend comprising a polyester, such as polyethylene terephthalate (PET), and a second component, where the second component may be a monomer that can be polymerized into the polyester suitably when the blend is melt processed at high temperatures, such as during polyester recovery. The blends may be used to produce articles of improved opacity (and / or reduced light transmittance), such as packaging articles (such as bottles, cans, trays, cups or films) and / or films / sheets, where after use of the articles, opacity may be reduced (and / or improved light transmittance) to facilitate recovery of the articles with a primary PET recovery stream.

Description

Technical Field

[0001] The present invention relates to a blend comprising a thermoplastic polymer. In particular, but not limited to, the present invention relates to blends for use in making articles such as packaging materials, films, and / or sheets. Preferred embodiments relate to articles (e.g., containers or films / sheets) that are bright white (e.g., high L*) and / or opaque or translucent and / or have high haze. Such articles are useful in household / personal care products that require a certain degree of opacity. Preferred embodiments are intended to facilitate the recycling of such articles with the main recycling stream to produce high-quality recycled PET (rPET). Background Art

[0002] The plastic packaging industry has long used inorganic particles such as titanium dioxide or calcium carbonate in PET to produce packaging with opacity, light-blocking properties and different colors, especially white, pastel and so-called "color opaque" packaging. More recently, polymers have also been used in PET packaging to produce opacity, light-blocking and whiteness. In these cases, the plastic may need to be stretched secondary 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-blocking properties, in which polymethylpentene and cycloolefin copolymer are added to the main PET plastic matrix together with inorganic shielding fillers including TiO2.

[0003] Other plastic containers that solve the same problem of protecting their contents (such as UHT long-shelf-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] One problem associated with current methods is that PET packaging (bottles, jars, trays, etc.) made from known materials cannot be recycled with the main PET recycling stream of clear, colorless or colored packaging to produce clear, high-value recycled PET (rPET) for use in making new PET packaging. Adding opaque / white PET packaging to the clear recycling stream in any proportion will produce a degree of haze or whiteness that is undesirable in the rPET if used to make new packaging (e.g., bottles or film). This means that currently, opaque or white PET packaging is destined for low-value applications such as strapping, building materials, fibers and insulation after recycling. Summary of the Invention

[0005] SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems.

[0006] The purpose of a preferred embodiment of the present invention is to produce articles (such as bottles, jars, trays, cups, films or sheets) that are bright white, opaque or translucent and / or have high haze and can be recycled with the main PET recycling stream of clear, 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 component.

[0008] Suitably, the blend is arranged to produce an article of increased opacity (and / or reduced light transmittance), such as a packaging article (e.g. a bottle, jar, tray, cup or film) and / or film / sheet, wherein after use of the article the opacity may be reduced (and / or light transmittance increased) to facilitate recycling of the article with the main PET recycling stream.

[0009] Suitably, the blend is arranged to be melt processed, such as injection molding or extrusion, to produce an article having relatively low light transmittance and / or high opacity compared to the polyester (e.g. PET) when used alone. Suitably, the blend also preferably has a relatively high L*, such as at least 65 or at least 70, as determined in Test 2. The second component may be an inorganic pigment, or at least act as a pigment in the blend and / or article made from the blend.

[0010] Preferably, the second component is arranged to react at an elevated temperature that is suitably above the blend's lowest melt processing temperature (e.g., at least 20°C or at least 30°C above) to produce a blend having higher light transmittance and / or lower opacity. Furthermore, the blend preferably has a lower level of visible particles of the second component (e.g., as observed under an optical microscope at 50-500x magnification) than the level of visible particles before treatment (preferably, substantially no visible particles of the second component). Thus, such a blend can be used to produce articles having low light transmittance, such as film / sheet and / or packaging article layers; after use of such articles (where low light transmittance is a desired characteristic), the blend and / or article can be treated at elevated temperatures (e.g., in a polyester recycling process) to produce polyester having higher light transmittance. After such elevated temperature treatment, the polyester (e.g., PET) can have a light transmittance and / or L* similar to that of virgin polyester (e.g., PET). Thus, the blend can be recycled as described to produce relatively high-quality (i.e., transparent) polyester, such as rPET.

[0011] Preferably, the second component is arranged to react with the polyester (eg in an acidolysis reaction). It may be arranged to react during recycling of the blend (eg at an elevated temperature of at least 290°C or 310°C).

[0012] The second component is preferably not a polymer. The second component is preferably not an oligomer. The second component is preferably not a dimer.

[0013] The second component is preferably not a dye. The second component is preferably not an inorganic material, such as a pigment. The second component is preferably not titanium dioxide.

[0014] The second component may be a monomer that is preferably polymerized into the polyester when the blend is melt processed at an elevated temperature (e.g., in a polyester recycling process). Preferably, the blend is arranged to be melt processed at a first temperature to produce a useful article or component of an article, wherein the second component does not substantially react with the polyester at the first temperature and / or wherein the second component remains as discrete particles dispersed in the polyester. Preferably, the blend is arranged to be melt processed at a second temperature, suitably after it has been melt processed at the first temperature and / or when it is in the form of a useful article or component of such an article. The second temperature is suitably higher than the first temperature, and the second component is arranged to polymerize into the polyester, suitably enabling the blend to be recycled and / or increasing the light transmittance of the blend.

[0015] Preferably, at the second temperature, the second component is arranged to react with the polyester, thereby forming a covalent bond between the polyester and the second component.

[0016] The second component is preferably an organic substance, which can be an organic acid, an organic acid derivative, or a salt derived from an organic acid.

[0017] The second component may comprise a carboxylic acid moiety or a derivative moiety of a carboxylic acid moiety.

[0018] The second component may comprise 1 to 5, preferably 1 to 3, more preferably 1 to 2 carboxylic acid moieties or derivative moieties of carboxylic acid moieties.

[0019] The second component may include a sulfonic moiety. For example, the second component may include -SO3, such as -SO3 - part.

[0020] The second component may contain 1-5, preferably 1-3, more preferably 1-2 sulfonic moieties, such as SO3 - part.

[0021] The second component preferably comprises an aromatic moiety. The second component preferably comprises 1-5, preferably 1-3, more preferably 1-2, and especially only one aromatic moiety. An organic acid, an organic acid derivative, or a salt derived from an organic acid may be attached to the aromatic moiety. For example, a carboxylic acid moiety or a derivative of a carboxylic acid moiety may be attached to the aromatic moiety. Alternatively, or preferably in addition, for example, a -SO3- The sulfonic moiety of the moiety may be attached to the aromatic moiety.

[0022] The aromatic moiety may comprise a single aromatic ring or a fused aromatic ring. The aromatic moiety (excluding any attached functional groups) may comprise only carbon and hydrogen atoms. For example, the aromatic moiety is preferably not a heteroaromatic moiety. The aromatic moiety is preferably a benzene moiety.

[0023] The second component preferably comprises:

[0024] at least one moiety that is a carboxylic acid moiety or a derivative moiety of a carboxylic acid moiety (referred to herein as "the first functional group"); and

[0025] At least one sulfonic moiety, such as SO3 - moiety (referred to herein as "the second functional group"),

[0026] Preferably, the first and second functional groups are bonded to the same aromatic moiety. In this case, preferably, the first and second functional groups are bonded to atoms in the aromatic moiety that are 1 and 3 relative to each other. The first and second functional groups may be meta to each other.

[0027] The second component may comprise the following parts:

[0028]

[0029] in:

[0030] X contains part -COO - ;and

[0031] Y contains some SO3 - ;

[0032] Wherein, suitably, the free bonds on the C atom and the S atom respectively represent bonds directly bonded to the benzene ring.

[0033] Preferably, Y is meta-bonded to X.

[0034] Preferably, X is -COOH. Preferably, Y is -SO3M, wherein M represents a metal or ammonium ion, and is preferably Na + .

[0035] The second component may comprise the following parts:

[0036]

[0037] wherein R represents an optional substituent, and n is 0 to 4.

[0038] R may be selected from the corresponding moieties of X and Y, or may represent a bridging atom or group (eg, to another aromatic moiety).

[0039] Preferably, the second component comprises the following parts:

[0040]

[0041] The hydrogen atoms of part III may be optionally substituted. Preferably, in part III, the part -CO2 - It is -COOH, partly -SO3 - It is -SO3Na.

[0042] In a preferred embodiment, the second component is selected from sulfoisophthalic acid (eg, SIPA) and sulfobenzoic acid (eg, SSBA).

[0043] The melting point (eg, onset of melting) of the second component may be greater than 300° C., or preferably greater than 325° C. The melting point of the second component may be less than 400° C. or less than 350° C.

[0044] The second component can be dispersed in the polyester, preferably substantially uniformly dispersed in the polyester. The second component is preferably in the form of particles, and preferably dispersed in the polyester as discrete particles. The particles can be observed under an optical microscope (magnification 50-500 times).

[0045] As used herein, "d 50 Particle size" is the median particle size, where 50% of the volume consists of particles larger than the d 50 d value, 50% of the volume is composed of particles smaller than the d 50 As used herein, the median particle size is the same as d 50 The particle size can be measured using a Beckman Coulter LS230 laser diffraction particle size analyzer.

[0046] The second component is preferably composed of d 50 The particle size is less than 200 μm, preferably less than 100 μm, more preferably less than 50 μm, and especially less than 25 μm. 50 It may be greater than 0.010 μm, preferably greater than 0.10 μm, and more preferably greater than 1.0 μm. 50 Measurements can be made as described herein.

[0047] Less than 5%, less than 3%, or less than 1% by weight of the particles of the second component may have a particle size greater than 100 μm, as measured as described herein. Preferably, at least 99%, more preferably about 100%, by weight of the particles of the second component have a size less than 100 μm, preferably less than 50 μm.

[0048] The second component preferably has a pKa, measured at STP, of less than 5.0. The pKa can be at least 1.0, at least 2.0, or at least 3.0. Preferably, the pKa is in the range of 3.0 to 5.0. If the pKa is too high, the second component may be too reactive toward polyester (e.g., PET). This may mean that during the first melt processing of a blend comprising the polyester and the second component, the second component reacts with the polyester polymer to produce an article, such as a packaging article. Any such reaction reduces the second component's ability to act as a pigment in the blend and, therefore, may not reduce the polyester's light transmittance as much as a second component that does not react with the polyester to the same extent. However, the second component preferably exhibits some reactivity toward the polyester so that it can react and form a covalent bond with the polyester when the blend is subsequently melt processed at a higher temperature (e.g., during a recycling step). Thus, the second component preferably exhibits a balance of properties—not being too reactive with the polyester at a first temperature at which the blend can be melt processed to produce a useful article, but reacting sufficiently with the polyester at a second temperature, which is higher than the first. The second temperature may represent a temperature at which the blend may be recycled alone or with other polyesters having different properties than the polyesters in the blend. The difference between the first temperature and the second temperature may be at least 10°C, 20°C, 30°C or 40°C.

[0049] Suitably, the blend comprises less than 2 wt%, preferably less than 1 wt%, more preferably less than 0.5 wt%, more preferably less than 0.1 wt% of particulate material other than the second component. Suitably, the blend comprises substantially 0 wt% of particulate material other than the second component.

[0050] The blend may be in the form of a masterbatch, such as a solid masterbatch, preferably in the form of granules or pellets.

[0051] The blend (herein a "masterbatch blend") may comprise the polyester (less than 50 wt. %) in combination with the second component.

[0052] The masterbatch blend may comprise at least 30 wt%, preferably at least 35 wt%, more preferably at least 40 wt% of the second component. The masterbatch blend may comprise less than 90 wt%, preferably less than 80 wt% or less than 70 wt% of the second component.

[0053] The sum of the weight percentages of the polyester and the second component in the masterbatch blend may be at least 80 weight percent, preferably at least 90 weight percent, more preferably at least 95 weight percent, and especially at least 98 weight percent. The balance may comprise additives selected from antioxidants, processing stabilizers, UV additives, compatibilizers, slip agents, and chemical or digital markers.

[0054] The masterbatch may comprise:

[0055] 40% to 80% by weight, preferably 55% to 65% by weight, of said polyester;

[0056] 20% to 60% by weight, preferably 35% to 45% by weight of the second component.

[0057] The polyester in the masterbatch blend can be PET, PBT, or copolymers thereof.

[0058] As an alternative to a masterbatch blend, the blend can be an article blend, which can be an article blend used to produce at least a portion of an article (e.g., a film / sheet or packaging article), or the blend itself can define at least a portion of an article (e.g., a film / sheet or packaging article). The article (e.g., a film / sheet or packaging article) can comprise or consist of the article blend. The packaging article described herein can be, for example, a bottle, a can, a tray, a cup, or a film, or a preform of a container.

[0059] Suitably, the container preform as described herein is a test tube shaped article which may be produced by injection moulding and which is suitably arranged to be stretch blow moulded to form a bottle.

[0060] The article blend may be formed in a melt processing apparatus and / or may define at least a portion of an article (e.g., a packaging article and / or film / sheet) suitably prepared by melt processing. The article may be a preform or a container (e.g., a bottle) which may be made by adding a masterbatch blend (e.g., as described above) to additional polyester to define an article blend.

[0061] The product blend may contain at least 0.5 wt%, preferably at least 1.0 wt%, more preferably at least 1.5 wt% of the second component. The product blend may contain less than 20.0 wt%, preferably less than 10.0 wt%, more preferably less than 6.0 wt% of the second component.

[0062] The article blend may comprise at least 80 wt%, preferably at least 90 wt%, more preferably at least 94 wt% of a polyester, preferably a single type of polyester, which is preferably polyethylene terephthalate (PET). The packaging blend may comprise less than 99 wt% of the polyester.

[0063] In the article blend, the sum of the weight percentages of the polyester (eg PET) and the second component is preferably at least 90 weight percent, more preferably at least 95 weight percent, especially at least 99 weight percent.

[0064] In the article blend, the ratio defined as the weight percent of polyester (e.g., PET) divided by the weight percent of the second component may be at least 12 and may be less than 80. This ratio is preferably in the range of 10 to 50.

[0065] The product blend may comprise:

[0066] 65 to 99 wt%, suitably 80 to 99 wt%, preferably 90 to 99 wt% polyester;

[0067] 1 to 35 wt%, suitably 1 to 20 wt%, preferably 1 to 10 wt% of the second component.

[0068] When the blend is an article blend, it can define at least a portion of an article (e.g., a packaging article and / or a film / sheet). The article blend can define a layer of a laminate or a layer of a container (e.g., a bottle, a can, a tray, or a cup). Such a layer can be combined with another layer made of a different material than the article blend. For example, the other material can have a lower solubility in water than the material of the layer made from the article blend.

[0069] The polyester of the first aspect, for example in a blend, a masterbatch blend or an article blend, is preferably polyethylene terephthalate, and in the context of this specification, the term may include copolyethylene terephthalate. The copolyethylene terephthalate of polyethylene terephthalate can comprise at least 85 mol % (for example at least 92 mol %, or at least 97 mol %) of terephthalic acid (or terephthalic acid derivatives) and at least 85 mol % (for example at least 92 mol %, or at least 97% mol %) of repeating units of ethylene glycol. In a preferred embodiment, the polyethylene terephthalate has a comonomer substitution of less than 10 mol %, more preferably less than 6 mol %, particularly less than 2 mol %. Preferably, the polyethylene terephthalate substantially comprises a homopolymer prepared by the esterification or transesterification of terephthalic acid or dimethyl terephthalate and ethylene glycol. Monomer can be subjected to polycondensation at high temperature in the presence of a catalyst in a vacuum.

[0070] As used herein, the term "IV" refers to the intrinsic viscosity of a polymeric material. It can be measured by dissolving 0.5 grams of polymer in 100 milliliters of a mixture of 60% by volume phenol and 40% by volume tetrachloroethane. 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 may be less than 0.80 dL / g.

[0071] According to a second aspect, there is provided a concentrated formulation for adding to polyester to reduce the light transmittance of the polyester and / or articles made therefrom, for example by melt processing the polyester with the formulation, the concentrated formulation comprising a carrier and the second component according to the first aspect.

[0072] The carrier may be a polyester and the concentrated formulation may be a solid masterbatch. In this case, the concentrated formulation may be a solid masterbatch and / or the concentrated formulation may be the "masterbatch blend" and may have any of the features of the masterbatch blend as described in the first aspect.

[0073] Alternatively, the concentrated formulation may be a liquid formulation comprising a liquid carrier and the second component.

[0074] The material state (e.g. liquid) mentioned herein refers to the state at standard temperature and pressure (STP). Thus, suitably, the liquid formulation is liquid at STP; and suitably, the liquid carrier is liquid at STP.

[0075] The concentrated formulation may contain at least 10 wt%, preferably at least 20 wt%, more preferably at least 25 wt% of liquid carrier. It may contain less than 70 wt%, preferably less than 60 wt%, more preferably less than 50 wt% of liquid carrier.

[0076] The concentrated formulation may contain at least 30 wt%, preferably at least 40 wt%, more preferably at least 50 wt% of the second component. It may contain less than 90 wt%, preferably less than 80 wt%, more preferably less than 75 wt% of the second component.

[0077] Preferably, the concentrated formulation comprises 50 wt% to 70 wt% of the second component and 30 wt% to 50 wt% of the polyester.

[0078] The liquid carrier is preferably a liquid at 25°C and atmospheric pressure. The liquid carrier should ensure that it has good solubility in the polyester to be added. It may comprise an oil (e.g. a vegetable oil or a mineral oil) or ethylene glycol. Typical carriers include hydrocarbons, hydrocarbon mixtures, alcohols, esters, polyethers and mixtures of two or more thereof. Compatible organic liquid carriers may be oil-based carriers. An example of such a carrier is ColorMatrix Europe Ltd (Address: Unity Grove 9-11, Knowsley Business Park, L34 9GT, Merseyside, UK) marketed under the trade name Clearslip TM 2. Clearslip TM 3&Process Aid-1 sold materials.

[0079] According to a third aspect of the present invention, there is provided an article, such as a film / sheet or a packaging article (such as a bottle, a can, a tray, a cup or a film), comprising the mixture according to the first aspect.

[0080] At least 90% by weight, preferably at least 95% by weight, more preferably at least 99% by weight of the layers of the article may consist of the blend.

[0081] A portion of the article comprising the blend may exhibit increased opacity (and / or decreased light transmittance) compared to an article made from polyester alone, and suitably, after use of the article, the opacity may be reduced (and / or the light transmittance increased) to facilitate recycling of at least the polyester-containing portion of the article with the main PET recycling stream.

[0082] The layers of the article may comprise:

[0083] 65 to 99% by weight, preferably 90 to 99% by weight, of polyester;

[0084] 1 to 35 wt%, preferably 1 to 10 wt% of the second component.

[0085] The article and / or the polyester-containing portion of the article may include an identification means to enable the article (or portion) to be identified as described herein and / or to be treated so that the opacity of the composition comprising the packaging article can be reduced (and / or the light transmittance increased), for example to facilitate recycling of the article with the main PET recycling stream. The identification means may be an identifier (e.g., a code) marked on the article, for example, which is not visible to the naked eye, or it may include an additive whose presence can be identified, for example, optically or otherwise. The identification means may be arranged to be identified by spectroscopic means, for example, by near-infrared radiation.

[0086] According to a fourth aspect of the present invention there is provided a method of producing an article, the method comprising melt processing a polyester and a second component to produce a blend.

[0087] The method may include treating the polyester (e.g., PET) to reduce the light transmittance of the polyester, wherein the method includes reducing the light transmittance of the polyester by blending the polyester with the second component, suitably by melt processing. Preferably, the method includes reducing the light transmittance of the polyester by dispersing the second component into the polyester, suitably such that discrete particles of the second component are visible in the polyester (e.g., using an optical microscope as described herein). The method may also include selecting the second component to react with the polyester at an elevated temperature (referred to herein as the "second temperature"), such that covalent bonds are formed between the polyester and the second component, suitably at the elevated temperature.

[0088] Preferably, the method produces a blend according to the first aspect. The polyester may be according to the first aspect. The second component may be according to the first aspect.

[0089] The method preferably includes melt processing the polyester and the second component at a temperature below the temperature at which the second component reacts with the polyester and / or forms covalent bonds with the polyester (referred to herein as the "first temperature").

[0090] The method of the fourth aspect may include:

[0091] (i) selecting a blend according to the first aspect and melt processing the blend to produce an article, such as a film / sheet or a packaging article, such as a preform for a container (e.g., a bottle); or

[0092] (ii) selecting a second component according to the first aspect and contacting the second component with the polyester (e.g., PET); and melt processing the second component and the polyester (e.g., PET) to produce an article, such as a film / sheet or a packaging article, such as a preform for a container (e.g., a bottle).

[0093] The method may comprise stretch blow moulding a preform to produce a packaging article in the form of a container, such as a bottle.

[0094] The method may comprise associating the identification device of the third aspect with the article.

[0095] Advantageously, the blend can be used to produce articles, such as films / sheets or packaging articles (e.g., bottles, jars, trays, cups, or films), having increased opacity (and / or reduced light transmittance), and after use of the article, the opacity can be reduced (and / or light transmittance increased) to facilitate recycling of the article. Preferably, by reducing opacity (and / or increasing light transmittance), the article or portion thereof can be recycled with the main PET recycling stream and / or recycled to produce transparent, high-value recycled PET (rPET). In one embodiment, multiple articles (e.g., bottles) containing the blend can be selected and processed together to achieve the reduced opacity (and / or increased light transmittance) as described above. The treated blend can then be mixed with the main recycling stream (e.g., containing other PET) to produce rPET.

[0096] Preferably, the article (e.g. container) has a light transmittance at 400 nm of less than 75%, for example less than 70%, suitably as determined by Test 1. The article may be arranged so that the second component can react with a polyester (e.g. PET) to produce a material which, if melt processed to produce another article (e.g. a bottle) of the same thickness, will have a light transmittance at 400 nm that is higher (e.g. at least 5% or at least 10%) than the light transmittance of the article (e.g. container) from which it was derived.

[0097] In a fifth aspect, the invention extends to a method of recycling an article (e.g., a film / sheet or packaging article) comprising selecting an article comprising a polyester and a second component and treating the article to reduce opacity (and / or increase light transmittance).

[0098] The recovery method may include:

[0099] (i) selecting an article or fragment of an article, wherein the article or fragment comprises a polyester and discrete particles of a second component dispersed in the polyester;

[0100] (ii) melt processing the article or the fragment at a temperature at which the second component reacts with the polyester (referred to herein as the "second temperature") and / or at a temperature at which the light transmittance of the melt processed product is greater than the light transmittance of the article or fragment selected in step (i).

[0101] Suitably, light transmittance may be assessed in a manner understood by those skilled in the art.

[0102] Discrete particles can be observed under an optical microscope (magnification 50-500 times).

[0103] The reaction in step (ii) can be confirmed by showing that the polyester after step (ii) contains relatively few (preferably substantially no) discrete particles of the second component, while the polyester from step (i) contains discrete particles of the second component. Suitably, the product of step (ii) is recycled polyester.

[0104] The method of the fifth aspect may include determining whether the article includes an identification device (e.g., as described in the third aspect) to confirm whether the article is as described herein and / or the article has been treated to reduce the opacity (and / or increase the light transmittance) of the blend comprising the packaging article. Thus, suitably, the method includes selecting an article that includes an identification device.

[0105] The method of the fifth aspect may comprise blending the article or fragment thereof selected in step (i) or treated as in step (ii) with additional polyester (e.g., PET). The additional polyester (e.g., PET) may comprise another polyester (e.g., PET), for example, a polyester having a relatively high light transmittance (and / or not containing significant amounts of additives that may be detrimental to the recycling stream), or a polyester (e.g., PET) derived from an article (e.g., a container) having a higher light transmittance at 400 nm than the comparable transmittance of the article selected in step (i).

[0106] In the method of the fifth aspect, granules or pellets of recycled PET (rPET) may be produced. The granules or pellets are preferably such that an injection-molded plaque having the same thickness as the article selected in step (i) has a light transmittance at 400 nm that is greater (e.g., at least 10% or at least 20%) than the light transmittance of the packaging article selected in step (i).

[0107] According to a sixth aspect, there is provided the use of a second component as described in any of the preceding aspects for increasing the opacity of polyester (e.g., PET) and / or reducing the light transmittance of a film / sheet or packaging article (e.g., a bottle, jar, tray, cup, or film), wherein the opacity can preferably be reduced or the light transmittance increased by a reaction involving the second component (e.g., an acid hydrolysis reaction) (suitably to facilitate recycling of the polyester (e.g., PET)). The present invention therefore extends to the use of the second component to increase opacity and / or reduce light transmittance as described above, and to improve the recyclability of the article.

[0108] In a seventh aspect, the invention extends to recycled PET (rPET), for example obtained by the process of the fourth aspect, and / or recycled PET (rPET) comprising a blend comprising a polyester and a second component as described herein, wherein suitably the blend is treated to react the second component with the polyester. The rPET may comprise the blend and additional PET, which may comprise PET from a source other than the blend.

[0109] Any aspect of any invention described herein may be combined with any other aspect of any invention described herein, with corresponding modifications as necessary. BRIEF DESCRIPTION OF THE DRAWINGS

[0110] Specific embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0111] Figure 1 is a graph showing the relationship between light transmittance and wavelength for Examples 4 to 9; and

[0112] Figure 2Graph showing the relationship between light transmittance and wavelength for Examples 6 and 10. DETAILED DESCRIPTION

[0113] The following materials are mentioned below:

[0114] PET-X—refers to a proprietary bottle-grade PET (lightweight C93 from Equippolymers, with an intrinsic viscosity (IV) of 0.80 + / - 0.02).

[0115] Sodium 5-sulfoisophthalate (SIPA) has a melting point in the range of 373-375°C and a particle size of less than 20 microns.

[0116] Sodium 3-sulfobenzoate of the following structure was obtained from Tokyo Chemical Industry UK Ltd. with a melting point in the range of 340-350°C and a particle size of less than 20 microns.

[0117]

[0118] Titanium dioxide - refers to ChemoursTi Pure R-104 rutile titanium dioxide pigment powder with a primary particle size of 3-5 microns.

[0119] Generally speaking, in a preferred embodiment, PET is melt-blended with a white crystalline organic material used as a pigment in a twin-screw extruder. This material is subsequently referred to as an "organic pigment." An organic pigment is a metal salt containing aromatic groups that is relatively incompatible with PET. Organic pigments can be processed with PET using standard processes (such as injection molding) to produce partially or completely opaque white articles, or by extrusion to produce films. Opacity / whiteness can be further increased by biaxial orientation and stretching (for example, in the injection stretch blow molding process commonly used to make PET bottles). It is believed that the organic pigment may act as a cavitating agent during the stretching and biaxial orientation of PET, creating voids in the PET, thereby increasing whiteness / opacity.

[0120] In a preferred embodiment, when desired, the polyester blend and articles made therefrom (such as containers and films) can be subjected to a further processing step in which the blend is remelted (e.g., in a twin-screw extruder) to allow the organic pigment to react with the PET (e.g., in an acid hydrolysis reaction). This reaction can result in a decrease in the IV of the PET. Organic pigment particles that were observable under an optical microscope (50-500 times magnification) prior to the step are now essentially invisible, resulting in a highly transparent extrudate. Thus, by using further processing steps, the polyester blend and articles can be recycled alone or in combination with a clear polyester source (e.g., a clear polyester bottle) to produce high-quality, clear recycled polyester.

[0121] This article covers the following tests:

[0122] Test 1—Measurement of light transmittance of blow-molded bottles

[0123] The light transmittance of each bottle was evaluated at a cut section of the bottle wall using a Shimadzu UV-visible spectrophotometer with an integrating sphere in the wavelength range of 300 nm–700 nm.

[0124] Test 2 - L*a*b* Color Space Evaluation of Blow Molded Bottles and Sheets

[0125] For bottles, first cut a small (60mm x 60mm) square section from the bottle wall. This section is placed on the sample stage of a Minolta CM3600A spectrophotometer, with the outer surface of the bottle section facing the instrument aperture. For samples, place the area of ​​interest on the sample stage of the Minolta CM3600A spectrophotometer. A D65 illuminant is used. L* is determined by measuring the reflectance of a black area on a Leneta Form 2A opacity chart using the LAV mask in specular exclusion mode.

[0126] Example 1 - General Procedure for Preform Manufacturing

[0127] The preforms were manufactured on a Husky GL160 injection molding machine equipped with a dual-cavity mold. PET-X and organic pigment were premixed manually and added to a hopper mounted above the injection molding machine's feed port. Standard PET injection molding processes were used to produce the preforms.

[0128] Example 2 - Alternative Procedure for Preform Fabrication Using Precomposite Materials

[0129] Alternatively, PET-X and organic pigment are separately fed at the desired mass feed rate via gravimetric feeders into the feed throat of a Thermo Prism TSE 24HC twin-screw extruder operating at temperatures typical of PET extrusion processes. The composite extrudate is cooled on a fan conveyor and pelletized. The collected pellets are then crystallized and dried using standard PET crystallization and drying procedures and used to manufacture preforms on a Husky GL160 injection molding machine equipped with a dual-cavity mold. The preforms are produced using standard PET injection molding techniques.

[0130] Example 3 - Bottle Production from Preforms

[0131] Preforms were stretch blow molded into 1-liter cylindrical bottles using a Sidel SB01 blow molding machine. A standard blow molding process was employed. The total oven power percentage was adjusted to achieve a preform temperature of 115°C to 120°C before the preforms left the oven and entered the blow mold. This is referred to as the blow temperature.

[0132] Examples 4 to 9 - Production of bottles using compounds

[0133] Following the procedure of Example 1, preforms were prepared by mixing PET-X and the specified organic pigments (Examples 4 to 6) or inorganic pigments (Examples 7 to 9) at the specified charging ratios, as shown in the following table.

[0134]

[0135] Bottles were blown from the preforms as described in Example 3 and the light transmittance of the bottles was evaluated as described in Test 1. Figure 1 As shown, the following table provides the cross-sectional thickness of the test samples for measuring light transmittance.

[0136] Example No. Wall section thickness (mm) PET-X 0.238 4 0.238 5 0.24 6 0.21 7 0.239 8 0.239 9 0.246

[0137] This graph shows that adding the specified pigments to PET-X reduces transmittance. The bottles generally appear opaque compared to bottles containing 100% PET-X. Furthermore, the incorporation of organic pigments (Examples 4 to 6) results in opacity comparable to that achieved using conventional inorganic pigments (Examples 7 to 9).

[0138] Example 10 - Recovery

[0139] The composite material of Example 6 was dried to a moisture content of <50 ppm using standard techniques known to those skilled in the art and incorporated into a 3:1 blend of PET-X and the material of Example 6. The composite material was then processed on a Thermo Prism 24HC twin-screw extruder with a barrel temperature set to 315°C and a throughput of 4 kg / hr, corresponding to a residence time of at least 2 minutes. During this extrusion step, sodium 3-sulfobenzoate reacted with the PET polyester. In this regard, it was observed that no sodium 3-sulfobenzoate particles were visible in the highly transparent extrudate. The extruded material was collected on an air-cooled conveyor belt, and the strands were then pelletized. The collected pellets were crystallized and then dried.

[0140] The reaction of sodium 3-sulfobenzoate with the polyester reduces the molecular weight of the polymer, thereby reducing the intrinsic viscosity. The dried material is then subjected to solid state processing (SSP) under vacuum at 210°C (applicable to PET and similar polyesters), a common operation performed on recycled polyester materials to promote reactions that increase the molecular weight of the polyester to a level suitable for the production of new articles, as determined by IV testing using appropriate tests.

[0141] The material was then processed into preforms and then bottles according to Examples 1 to 3. The light transmittance of these bottles was then evaluated as described in Test 1. The results are shown in Table 1. Figure 2The figure also includes the results for the virgin composite, Example 6, and PET-X. Example 10 shows the results for the material treated in this example.

[0142] Example 11 - L* Value

[0143] The composite materials detailed in selected Examples were evaluated for L* following the procedure described in Test 2, and the results are shown in the table below.

[0144] Example No. L*(D65) 4 68.12 5 78.4 6 62.76 9 84.78 PET-X 10.3 10 22.59

[0145] From these and other experiments, the inventors have concluded that organic pigments have the following advantageous properties: they can be blended with polyester (e.g., PET) to produce a blend that, on the one hand, can be used to make opaque bottles; and, on the other hand, can subsequently be treated to substantially eliminate the opacity (and / or bring the light transmittance of the blend to or near that of pure PET), thereby allowing the blend to be recycled with substantially pure PET obtained from bottles (or other sources).

[0146] Favorable characteristics include the following:

[0147] (i) High melting point: above the typical target polymer processing temperature. For PET, this means >300°C.

[0148] (ii) Contains at least one aromatic ring having at least one carboxyl group thereon.

[0149] (iii) There is at least one strong electron-withdrawing group attached to the same aromatic ring as the carboxyl group.

[0150] (iv) The material is crystalline, forming white or colorless crystals.

[0151] The present invention is not limited to the details of the foregoing embodiments. The present invention extends to any novel feature or combination of novel features disclosed in this specification (including any accompanying claims, abstract and drawings), or any innovative step or combination of innovative steps in any disclosed method or process.

Claims

1. A blend comprising a polyester, such as polyethylene terephthalate (PET); and a second component.

2. The blend of claim 1 , wherein the blend is arranged to produce an article having increased opacity, wherein after use of the article, the opacity can be reduced to facilitate recycling of the article with the main PET recycling stream.

3. A blend according to claim 1 or 2, wherein the second component is arranged to react at an elevated temperature to produce a blend having a higher light transmittance and / or a lower opacity than the blend before the reaction.

4. A blend according to any preceding claim, wherein the second component is arranged to react with the polyester in an acidolysis reaction and / or thereby form a covalent bond between the polyester and the second component.

5. The blend according to any one of the preceding claims, wherein the second component is not a polymer and / or is not an oligomer and / or is not a dimer and / or is not a dye and / or is not an inorganic material.

6. A blend according to any preceding claim wherein the second component is a particle and is dispersed in the polyester as discrete particles.

7. The blend according to any preceding claim, wherein the second component is composed of 50 The particle size is less than 200 μm (preferably less than 50 μm), and optionally, the particle size is less than 200 μm (preferably less than 50 μm). 50 Greater than 0.010 μm (more preferably greater than 1.0 μm).

8. A blend according to any preceding claim, wherein the second component is a monomer, wherein at a first temperature the second component is substantially unreactive with the polyester, and / or wherein the second component is arranged as discrete particles dispersed in the polyester; and wherein the blend is arranged to be melt processed at a second temperature, higher than the first temperature, at which temperature the second component is polymerized into the polyester, suitably allowing the blend to be recycled and / or increasing the light transmittance of the blend.

9. The blend according to any preceding claim, wherein the second component comprises 1 to 5 carboxylic acid moieties or derivatives of carboxylic acid moieties.

10. A blend according to any preceding claim wherein the second component comprises 1 to 5 sulfonic moieties, such as SO3 - part.

11. A blend according to any preceding claim, wherein the second component comprises an aromatic moiety, preferably a benzene moiety.

12. The blend according to any preceding claim, wherein the second component comprises: at least one moiety that is a carboxylic acid moiety or a derivative moiety of a carboxylic acid moiety (referred to herein as "the first functional group"); and At least one sulfonic moiety, such as SO3 - moiety (referred to herein as "the second functional group"); wherein the first functional group and the second functional group are bonded to the same aromatic moiety.

13. The blend according to any preceding claim, wherein the second component comprises the following parts: in: X contains part -COO - ;and Y contains part -SO3 - ; The free bonds on the C and S atoms represent the bonds directly bonded to the benzene ring.

14. A mixture according to any preceding claim, wherein the second component has a melting point (e.g. onset of melting) greater than 300°C, or preferably greater than 325°C; and / or a temperature below 400°C or below 350°C.

15. The blend according to any preceding claim, wherein the second component has a pKa measured at STP of less than 5.0; and / or a pKa of at least 1.

0.

16. A mixture according to any preceding claim, wherein the blend comprises less than 2 wt% of particulate material other than the second component.

17. A blend according to any preceding claim, wherein the blend is a masterbatch, such as a solid masterbatch in the form of granules or pellets.

18. The blend of claim 15, wherein the masterbatch blend comprises: 40% to 80% by weight, preferably 55% to 65% by weight, of said polyester; 20% to 60% by weight, preferably 35% to 45% by weight of the second component.

19. The blend according to any one of claims 1 to 14, wherein In an article blend, the sum of the weight percentages of the polyester (e.g., PET) and the second component is at least 90 weight percent; and the ratio, defined as the weight percent of the polyester (e.g., PET) divided by the weight percent of the second component, is at least 12 and less than 80, wherein the article blend comprises: 80% to 99% by weight, preferably 90% to 99% by weight, of polyester; 1 to 20 wt%, preferably 1 to 10 wt% of the second component.

20. A blend according to any preceding claim wherein the polyester is polyethylene terephthalate having less than 10 mol % (preferably less than 2 mol %) comonomer substitution.

21. The blend of any preceding claim wherein the polyester is polyethylene terephthalate, which consists essentially of a homopolymer prepared by esterification or transesterification of terephthalic acid or dimethyl terephthalate with ethylene glycol.

22. The blend of any preceding claim, wherein the IV of the polyester in the blend is greater than 0.5 dL / g, and optionally less than 0.80 dL / g.

23. A blend according to any preceding claim in the form of a concentrate formulation for addition to a polyester to reduce the light transmittance of the polyester and / or articles produced therefrom, the concentrate formulation comprising a carrier and a second component according to any preceding claim.

24. The blend according to claim 23, wherein the concentrated formulation comprises at least 10 wt%, preferably at least 25 wt% of a liquid carrier; and / or comprises less than 70 wt%, preferably less than 50 wt% of a liquid carrier.

25. The blend according to claim 23 or 24, wherein the concentrated formulation comprises at least 30 wt%, preferably at least 50 wt% of the second component; and / or comprises less than 90 wt%, preferably less than 75 wt% of the second component.

26. The blend of any one of claims 18 to 20, wherein the concentrated formulation comprises 50% to 70% by weight of the second component and 30% to 50% by weight of the polyester.

27. An article, such as a film / sheet or a packaging article (such as a bottle, jar, tray, cup or film), comprising a blend according to any preceding claim.

28. The article of claim 27, wherein a layer of the article comprises: 80% to 99% by weight, preferably 90% to 99% by weight, of polyester; 1 to 35 wt%, preferably 1 to 20 wt% of the second component.

29. A method of producing an article, such as an article according to claim 27 or 28, comprising melt processing the polyester and a second component to produce a blend.

30. The method of claim 29, comprising reducing the light transmittance of the polyester by dispersing the second component in the polyester such that discrete particles of the second component are visible in the polyester; and further comprising selecting the second component to react with the polyester at an elevated temperature (herein referred to as the "second temperature") such that covalent bonds are formed between the polyester and the second component at the elevated temperature.

31. A method according to claim 29 or 30, wherein the method produces a blend according to any one of claims 1 to 26.

32. A method for recycling an article, such as a film / sheet or packaging article, comprising selecting an article comprising a polyester and a second component and treating the article to reduce opacity (and / or increase light transmittance).

33. The method of claim 32, wherein the recovery method comprises: (i) selecting an article or fragment of an article, wherein the article or fragment comprises a polyester and discrete particles of a second component dispersed in the polyester; (ii) melt processing the article or the fragment at a temperature at which the second component reacts with the polyester (referred to herein as the "second temperature") and / or at a temperature at which the melt processed product has a light transmittance greater than the light transmittance of the article or fragment selected in step (i).

34. A method according to claim 33, comprising blending the article or fragments thereof selected in step (i) or treated as in step (ii) with an additional polyester (e.g. PET).

35. Use of the second component according to any one of claims 1 to 26 for increasing the opacity of polyester (e.g. PET) and / or reducing the light transmittance of films / sheets or packaging articles (e.g. bottles, jars, trays, cups or films), wherein the opacity is reduced or the light transmittance is increased by a reaction involving the second component and the polyester.

Images