Method for colouring polyesters, and master batch composition therefor

Abstract

The invention relates to a method for colouring polyesters such as PET, comprising at least the following method steps: (a) providing a first component, substantially consisting of one or more polyesters and / or a recycled polyester material, (b) providing a second component, and (c) mixing and melting the two components. According to the invention, the second component consists of at least one PEF mixed with a colourant. Mixing and melting the two components results in a plastics mixture having a dye or colour which differs from the dye or colour of the first component. The resulting plastics mixture has, for example, a stronger tint, a different colour, a more intense colour and / or a darker colour than the first component originally has. The invention also relates to a master batch for colouring polyesters, in particular recycled polyester material, such as PET or in particular rPET, the master batch containing PEF mixed with a colourant.

Description

[0001] Process for coloring polyesters and masterbatch composition therefor

[0002] Field of the invention

[0003] The invention relates to a process for dyeing polyesters according to the preamble of claim 1.

[0004] State of the art

[0005] Humanity's resource consumption inevitably leads to the need to reuse raw materials for recycling. Of all plastics, polyesters, especially polyethylene terephthalate (PET), play one of the most important roles in terms of recycling. This is also due to the fact that polyester chains can be subjected to both mechanical and chemical recycling processes, and the degradation of polyester chains can be repaired during processing or at the recycling plant.

[0006] Today, thousands of tons of PET are recycled every year into new packaging, textiles, etc. using mechanical and chemical recycling processes.

[0007] It is often desired to modify the properties of plastic materials. This also applies to recycled plastic materials. This can be achieved through additives. Additives generally serve to introduce active substances or active ingredients that influence the properties of the plastic. Active substances are chemical substances or compounds that produce a chemical or physical effect on the starting plastic. For example, acetaldehyde scavengers, oxygen scavengers, infrared absorbers, UV absorbers, nucleating agents, and / or lubricants are frequently added.

[0008] Plastics, especially polyesters such as polyethylene terephthalate (PET), can contain colorants. Colorants are essentially divided into dyes and pigments. Chemical substances and compounds that have the property of coloring other materials can be referred to as colorants. According to DIN 55934, dyes are those colorants that are soluble in their application medium. Insoluble colorants are called pigments.

[0009] The coloring of plastics with dyes and pigments can be considered a type of additive. Coloring, for example, changes the color and / or color intensity. Colored PET can be problematic for recycling, partly because there are many different colors and only a very few colors have their own collection, sorting, and recycling processes, currently mostly only for transparent, green, and blue PET. This is also problematic because colors cause technical problems in the recycling process.

[0010] In the PET manufacturing process (which includes film extrusion, injection molding, blow molding and thermoforming processes), colors are not added in their pure form, but as a masterbatch in which the colorants are already finely distributed in a carrier material.

[0011] Carrier materials can include glycerides, fats, oils, fatty acids, and oleic acids. This carrier, such as rapeseed oil, is added to the PET during each new processing step to incorporate additives and colors, and accumulates with each subsequent cycle in the recycling process.

[0012] Rapeseed oil, for example, has limited heat stability and degrades over time during the recycling process. Degradation products are formed that yellow the PET, reduce its viscosity, and / or act as chain terminators that interrupt polycondensation or polymerization during the chemical recycling process.

[0013] Known carrier systems that result in less yellowing, degradation products, and chain breakers during recycling include PET or PET copolymers or polybutylene terephthalate (PBT). However, these known systems and many other carrier systems pose significant problems either during their manufacturing process or later in the recycling cycle.

[0014] Amorphous PET as a carrier material becomes plastic, soft, and sticky far too quickly, usually at temperatures between 60°C and 100°C, depending on the copolymer content. Since the PET to be colored is usually dried at temperatures above 100°C, amorphous PET as a carrier material inevitably leads to adhesions, sticking, and thus disruptions in the production process.

[0015] Crystalline PET as a carrier softens and melts at temperatures between 215°C and 250°C, depending on the degree of copolymerization. Adhesion and bonding problems do not exist, as PET is usually dried below 195°C. However, if the crystalline PET as a carrier melts at the same time as the polyester material to be colored, or too late, the carrier cannot achieve homogeneous mixing with the polyester material to be colored, despite the mixing and shearing action of the screw during the extrusion process, and thus cannot be distributed sufficiently evenly during plasticizing. This primarily affects carrier PET variants that melt at the same temperature as the PET to be colored, or only 5°C to 15°C lower. Polybutylene terephthalate (PBT) as a carrier is very frequently used in PET additives and coloring.Depending on the copolymer content, crystalline PBT melts at temperatures between 210°C and 230°C, making it ideal as a carrier material. However, PBT can have a detrimental effect on the properties of PET. This is not normally a problem when colored for the first time, but can become problematic during repeated recycling and coloring, where the PBT accumulates through repeated additions during the recycling process. Firstly, the PBT itself in PET is viewed as a contaminant and cannot be removed using either mechanical or chemical recycling methods. Secondly, the process temperatures prevailing during recycling can lead to undesirable degradation reactions (such as the formation of tetrahydrofuran), resulting in the formation of degradation products that negatively impact the material properties of the PET.

[0016] Object of the invention

[0017] The objective is to improve the recyclability of colored polyesters, particularly colored PET. The recyclate should be particularly suitable for stretch blow molding bottles and containers. Furthermore, the objective is to provide a carrier system that poses fewer or no problems during chemical and mechanical recycling. Furthermore, the disadvantages of the described prior art should be avoided. For example, the accumulation of PBT through multiple recycling cycles should be prevented. In particular, the objective is to provide an alternative carrier system for the purpose of coloring polyesters that is also suitable for recycled or repeatedly recycled material, such as rPET.

[0018] The further objective is to provide a colored preform suitable for stretch blow molding bottles. In particular, the objective is to provide a colored preform consisting primarily of polyester(s) and suitable for stretch blow molding bottles and containers. Furthermore, bottles and containers produced in this way should be recyclable, allowing them to be further processed into bottles and containers after recycling.

[0019] Description

[0020] The stated problem is solved in a process for dyeing polyesters by the features stated in the characterizing portion of patent claim 1. Further developments and / or advantageous embodiments are the subject of the dependent patent claims.

[0021] Further advantages and features will become apparent from the following description of embodiments and variants of the invention.

[0022] A method is described for coloring polyesters, such as PET, which are suitable for producing preforms, in particular stretch-blow-moldable preforms, i.e. preforms which can be further processed into a hollow body by means of a stretch blow molding process. The method for coloring polyesters, such as PET, which are suitable for producing preforms, has at least the following method steps: (a) providing a first component consisting of one or more polyesters and / or a polyester recyclate, (b) providing a second component (this is also called a masterbatch), and (c) mixing, shearing and melting the two components, wherein the second component consists at least of a PEF mixed with a colorant.

[0023] The PEF of the second component serves as a carrier for at least one colorant.

[0024] Also described is a method for producing a preform from polyester, in particular PET, comprising the method for coloring polyester with its method steps (a), (b) and (c) and further comprising the method step (d), ie the molding of a preform from the colored polyester, e.g. by injection molding.

[0025] Also described is a method for producing a hollow body, such as a bottle or a container, from polyester, comprising the method for coloring polyester with its process steps (a), (b) and (c), the further processing of the preform to a hollow body according to process step (d) and further comprising process step (e), ie the forming of a hollow body from the preform by stretch blow molding.

[0026] When the two components are mixed, sheared and melted (which can take place, for example, in an extruder by adding the second component at the beginning of the extrusion process), a plastic mixture is created with a color that differs from the color of the first component. The resulting plastic mixture has, for example, a stronger tint, a different color, a more intense color and / or a darker color than the first component originally had, or contains a higher concentration of a colorant or contains one or more additional colorants. The mixing, shearing and melting of the different components preferably takes place in an extruder. The different components are expediently mixed in the melt by adding the second component. The second component is preferably added as early as possible during the extrusion process.In this context, "as early as possible at the beginning of the extrusion process" means that the second component is added at or just above the extruder inlet, where there is no melt yet, i.e., where the first component has not yet melted. Alternatively, the components could be premixed in a solid state by using a premixer directly upstream of the extruder inlet.

[0027] A process is also described comprising the coloring of polyester, such as PET, the forming of a preform from the colored polyester and the stretch blow molding of a hollow body from the preform.

[0028] PEF is the abbreviation for polyethylene furanoate or more precisely poly(ethylene-2,5-furandicarboxylate), a thermoplastic from the polyester family.

[0029] PET is the abbreviation for polyethylene terephthalate, a thermoplastic from the polyester family, usually produced by polycondensation. rPET is the abbreviation for PET recyclate.

[0030] The one or more polyesters and / or the polyester recyclate of the first component, if present, are preferably essentially PET plastic materials. Polyester material or PET material that is suitable for the production of beverage bottles is particularly preferred. PET material that can be recycled in a PET recycling cycle, in particular in the PET recycling cycle for beverage bottles, is particularly advantageous. The polyester recyclate of the first component, if present, preferably originates from beverage bottle production and / or beverage bottle recycling. This is preferably PET recyclate (rPET), in particular from the PET recycling cycle for beverage bottles. The polyester, PET or rPET used therefore expediently has a quality that is suitable for beverage packaging or is typically used for beverage packaging.This means that the PET or rPET used should be colored in such a way that, upon repeated coloring, the material properties are not adversely affected by the carrier. This particularly means that material properties relevant to the processability and suitability of the PET or rPET material in the production and use of beverage bottles should not deteriorate as a result of coloring or fall outside the normally tolerated property ranges.

[0031] The polyester material or polyester recyclate of the first component may contain small amounts of PEF and / or other copolymers and / or additives, such as colorants, and / or impurities, as is common, particularly for beverage packaging grades. PET or rPET, in particular, may contain PEF, other copolymers, other additives, and / or impurities, especially if the material of the first component has already undergone one or more recycling cycles. The amount of PEF and / or other copolymers and / or additives increases with the number of recycling cycles the material has already undergone.

[0032] The proportion of the first component, i.e., the proportion of the material to be colored, is preferably as high as possible. The proportion of the first component can, for example, make up to 99.99 wt.% of the mixture, i.e., the sum of the first and second components.

[0033] The proportion of the second component, i.e., the proportion of the colorant together with the carrier, preferably amounts to 0.01% to 15% by weight of the sum of the first and second components. Generally speaking, the higher the proportion of the second component, the less efficient the dyeing process and the more contaminated the resulting material, making it less suitable for further recycling.

[0034] PET achieves its special properties through the effect of strain hardening, which occurs through interactions between the individual PET molecules. Any contamination or copolymerization reduces this interaction and thus weakens the products made from it.

[0035] The proportion of colorant in the second component expediently makes up 0.01 wt.% to 70 wt.%, preferably 5 wt.% to 70 wt.%, more preferably 20 wt.% to 70 wt.%, more preferably 35 wt.% to 70 wt.%, more preferably 40 wt.% to 70 wt.%, of the second component. In principle, the higher the colorant loading in the second component, the more cost-effective the coloring and the less carrier material is introduced into the material to be colored. The higher the concentration of the colorant or color-imparting active substance in relation to the carrier, the poorer the distribution in the polymer mass to be colored.

[0036] The proportion of PEF in the second component therefore expediently makes up at least 30 wt.% of the second component. This ensures that a sufficiently homogeneous distribution of the colorant in the first component is achieved. The mixing, shearing and melting of the two components causes a coloration or colour of the resulting plastic mixture, in particular of the resulting plastic mixture in the cooled state, which differs from the coloration or colour of the first component. A different colouration is particularly evident, for example, in a stronger tint, different colour, more intense colour and / or darker colour of the resulting plastic mixture than the first component originally had. The mixing, shearing and melting of the two components should in particular lead to the most homogeneous mixing of the two components and thus the most homogeneous distribution of the colourant in the first component.

[0037] Also described is a product made of plastic material, in particular of colored plastic material, produced from at least one mixture of the first component consisting essentially of a polyester, several polyesters and / or a polyester recyclate and the second component consisting essentially of a PEF mixed with a colorant.

[0038] Described below is a masterbatch or masterbatch composition for coloring polyesters, such as PET, in particular for coloring recycled polyester, such as rPET, for preforms. The masterbatch or masterbatch composition essentially comprises PEF and colorant, in particular PEF mixed with a colorant. Optionally, further additives can be added, provided the additives do not conflict with the use of the masterbatch composition for producing preforms for the stretch blow molding process. The aforementioned second component—considered separately—can be referred to as a masterbatch.

[0039] The masterbatch is produced through a compounding process. The goal of compounding is to ensure that the pigments and dyes are distributed as finely as possible within the masterbatch and do not form agglomerates. The shearing and mixing processes (especially an extruder) in preform production are unsuitable for achieving a fine distribution of the colorants without agglomeration in the material to be colored if the colorants are added directly to the material to be colored.

[0040] The use of the masterbatch or masterbatch composition as a second component in an extrusion blow molding process is further described, in which a material or material mixture to be colored is added as the first component, the second component during the extrusion process, in particular at the beginning of the extrusion process, whereby the two components (ie the material or material mixture to be colored and the masterbatch) mix and melt and then the ideally as homogeneously mixed component mixture is bias molded into a product.

[0041] Due to a similar viscosity of the material to be colored or the material mixture to be colored (ie the first component) and the masterbatch (ie the second component), shear forces occur when these are mixed, which help to distribute the colorants of the masterbatch (ie the second component) evenly in the material to be colored or the material mixture (ie the first component).

[0042] Due to the melting behavior in the extrusion process of any polyester container production, masterbatches (second component) with a lower melting point than the respective polyester material (first component) are preferred, as this makes homogeneous mixing easier to achieve. For these reasons, masterbatch compositions or carrier materials with a lower melting point than PET are particularly preferred, for example in PET bottle production. In general, combinations of the first and second components are preferred in which the melting point of the second component, i.e. essentially the melting point of the carrier material (which is contained in the second component or in the masterbatch composition), is 15°C, more than 15°C or optionally more than 20°C lower than the melting point of the first component, i.e. essentially the melting point of the polyester material (or the polyester bottle material).Particularly preferably, the melting point of the second component or the carrier material contained therein is more than 15°C to a maximum of 20°C lower than the melting point of the first component (i.e., the polyester bottle material, such as PET). This applies in particular to PET and rPET beverage bottle materials.

[0043] The water content in the masterbatch or the second component is advantageously a maximum of 0.04 wt.% or less, based on the masterbatch composition or the second component. The water content in the masterbatch or the second component is predominantly contained in its PEF material portion.

[0044] Both pigments and dyes can be used as colorants, and combinations of these are also conceivable.

[0045] Additional additives are possible, e.g., acetaldehyde scavengers, oxygen absorbers, infrared absorbers, UV absorbers, and lubricants. In particular, a masterbatch or masterbatch composition is disclosed which comprises PEF mixed with one or more colorants and optionally one or more active substances from the group consisting of acetaldehyde scavengers, oxygen scavengers, IR absorbers, UV absorbers, and lubricants. In a particularly preferred embodiment, a masterbatch or masterbatch composition is disclosed which consists of PEF mixed with one or more colorants and optionally one or more active substances from the group consisting of acetaldehyde scavengers, oxygen scavengers, IR absorbers, UV absorbers, and lubricants.Since the process according to the invention is intended, among other things, to prevent PBT from accumulating through a plurality of recycling cycles, it is particularly expedient that the masterbatch composition and thus the masterbatch contains as little or essentially no PBT as possible, preferably no PBT at all.

[0046] Dyes are molecules that absorb light. Preferably used dye molecules are conveniently selected from a group consisting of solvent dyes and / or combinations thereof. Commonly used dyes include:

[0047] - 2-(2-quinolyl)-1,3-indanedione (ie Solvent Yellow 33),

[0048] - 2-(3-Hydroxyquinolin-2-yl)-1H-indene-1,3(2H)-dione (ie Solvent Yellow 114),

[0049] 1.4-bis(butylamino)anthracene-9,10-dione (i.e. Solvent Blue 35),

[0050] 1,4-Bis(mesitylamino)anthraquinone (i.e. Solvent Blue 104), 1-[(1-methylethyl)amino]anthraquinone (i.e. Solvent Red 169), and

[0051] - 8,9,10,11-tetrachloro-12H-phthaloperin-12-one (i.e. Solvent Red 135)

[0052] Pigments are colored particles. Typical pigments for black are carbon black or iron oxide black. A typical pigment for white is titanium dioxide. Typical effect pigments are mica (i.e., mother-of-pearl). Pigments preferred for beverage bottle production are titanium oxides, especially titanium dioxide, iron oxides, and mica. Combinations of different pigments are also possible.

[0053] Iron oxides, titanium oxide and mica are preferably in crystalline form and can optionally be coated with organic and inorganic materials.

[0054] Titanium oxide pigment particles preferably consist of titanium dioxide. The preferably used titanium oxide pigment is present in at least 70 wt.%, preferably at least 80 wt.%, particularly preferably at least 90 wt.% crystalline form, in particular in the rutile crystal form, i.e., as rutile. Rutile is preferred because it has particularly high hiding power. The titanium oxide crystals can optionally be coated.

[0055] An inorganic oil such as silicone oil or an organic oil (e.g., rapeseed oil) can be used as a coating. This can suppress or reduce any potential nucleating effect of the pigment. The pigment particles are preferably pre-ground to a size in the range of 100 nm to 2000 nm, more preferably to a size in the range of 200 nm to 400 nm.

[0056] The reason for the preferred size is that in the stretch blow molding process, the manufactured preforms are heated using IR light so that they can then be stretched into bottles. If the pigments are too large, they can scatter or block the IR light, resulting in a preform that is not fully heated and therefore cannot be stretched.

[0057] Pigments with an average value of <100 nm are avoided if possible, as they may be considered undesirable nanomaterials.

[0058] If pigments are used, the loading of colorant in the masterbatch (or in the second component) is advantageously preferably in the range from 1 wt.% to 70 wt.%, more preferably 5 wt.% to 70 wt.%, more preferably 20 wt.% to 70 wt.%, more preferably 35 wt.% to 70 wt.%, more preferably 40 wt.% to 70 wt.% or more preferably 40 wt.% to 60 wt.%. The PEF content of the masterbatch is accordingly preferably 99 wt.% to 30 wt.%, more preferably 95 wt.% to 30 wt.%, more preferably 80 wt.% to 30 wt.%, more preferably 65 wt.% to 30 wt.%, more preferably 60 wt.% to 30 wt.% or more preferably 60 wt.% to 40 wt.%, so that the PEF content and the colorant content together make up essentially 100% of the masterbatch material, insofar as no further additives or impurities are present or these can be neglected.In principle, other additives of a different type can be added to the masterbatch consisting of colorant and PEF, for example, replacing part of the aforementioned colorant content. Overall, it is advisable for the PEF content of the masterbatch to be at least 30% by weight, while the remaining portion of the masterbatch, up to a maximum of 70% by weight, consists primarily of colorant and, if appropriate, other additives.

[0059] In the masterbatch or in the second component, the weight ratio of pigment to PEF is expediently in the range from 1:99 to 70:30, preferably 5:95 to 70:30, more preferably in the range from 20:80 to 70:30, more preferably in the range from 35:65 to 70:30, more preferably in the range from 40:60 to 70:30.

[0060] If dyes are used as colorants, the colorant load in the masterbatch or in the second component is expediently 0.01 wt% to 20 wt%, preferably 5 wt% to 20 wt%. The weight ratio of dyes to PEF is expediently in the range from 0.01:99.99 to 20:80, preferably in the range from 5:95 to 20:80. The PEF is advantageously present in the masterbatch or in the second component as a crystallized material; in particular, the PEF has a degree of crystallization of 10% or more, or preferably 20% or more. In practice, the degree of crystallization is in the range from 10 to 70%, or preferably in the range from 20% to 70%. A crystallized masterbatch with a crystallization of more than 20% of the PEF has the advantage that the masterbatch material only bonds at temperatures above 185°C.

[0061] The masterbatch or the second component is in the form of granules, particularly strand granules. This facilitates mixing into the first component to be colored. The first component is advantageously also in the form of granules. The granules preferably have a maximum size of 2 mm to 5 mm in their largest dimension. The granules are expediently cylindrical or spherical, for example. The granules are fed into the extruder and melted there, where the components are mixed.

[0062] The PEF carrier is conveniently produced by polycondensation of monoethylene glycol with furandicarboxylic acid. It is particularly advantageous to use biological or biologically produced starting materials, i.e., biomonoethylene glycol and biofurandicarboxylic acid. The polycondensation product is further condensed (also referred to as further polymerization) to an IV (intrinsic viscosity) of 0.6 to 0.8 dl / g (measured according to ASTM D4603).

[0063] The PEF used to produce the second component or the PEF carrier is preferably a polycondensation product which consists essentially, in particular 80% by weight or more, of PEF and may optionally contain additional comonomers.

[0064] Hollow polyester containers, especially PET containers, are typically manufactured using the stretch blow molding process. A polyester material, such as PET, is first injected into a preform. The preform is then blown into a bottle and stretched at temperatures just above the glass transition temperature, which for PET is between 80°C and 130°C. This stretching process gives the material its enormous strength.

[0065] It is important that the injection-molded preform is in an amorphous state or essentially in an amorphous state and is therefore soft and stretchable in the glass transition temperature range, i.e. in the case of PET in the temperature range of approximately 80 to 130°C. Crystalline regions are hard and non-stretchable, i.e. they can no longer be deformed using a stretch blow molding process. Therefore, the preform should contain as few crystalline regions as possible. A PET material used for the production of preforms (i.e. PET and / or PET recyclate) is preferably modified with copolymers and / or diethylene glycol and / or isophthalic acid in order to prevent premature crystallization of the PET material. In addition, after injection molding the preform is cooled as quickly as possible in order to give the material or the molecules as little time as possible to form crystalline structures.

[0066] Colorants for preforms should, if possible, have no nucleation effect, since, as shown above, a crystalline preform in the glass transition temperature range (such as PET at 80 to 130 °C) is too hard and therefore no longer stretchable.

[0067] When pigments are used as colorants, it may be necessary to condition them through a surface treatment so that they can be easily distributed in polyesters, such as PET, but do not act as a starting point for crystallization (i.e., do not have a nucleating effect). In particular, the pigments should not contain any PET-like groups, which could serve as a starting point for crystallization in polyester materials, especially PET. For example, by coating the pigment particles, a crystallizing effect of the pigments can be suppressed or prevented.

[0068] Implementation example 1

[0069] In one embodiment, a PEF masterbatch contains 50 weight percent PEF and 50 weight percent titanium oxide pigment. The pigment particles used have a size range of 200 nm to 400 nm. The majority of the titanium oxide pigment particles are in the "rutile" crystallization form. More preferably, the titanium oxide is present in the rutile crystal form to an extent of over 90 weight percent.

[0070] Implementation example 2

[0071] In one embodiment, a PEF masterbatch contains 50 weight percent PEF and 50 weight percent titanium oxide pigment. The pigment particles used have a size in the range of 200 nm to 400 nm. The majority of the titanium oxide pigment particles are in the crystallization form "anatase." Particularly preferably, the titanium oxide is present in anatase form to an extent of over 90 weight percent. Advantages of the invention

[0072] The use of PEF as a carrier material for additives and especially for colorants brings the following advantages:

[0073] PEF (polyethylene furanoate, i.e., polyethylene-2,5-furandicarboxylate) has a melting point of 190°C to 240°C, ideally between 210°C and 230°C, depending on the copolymer content. It therefore melts significantly earlier than the PET being processed, which melts in the range of approximately 250°C to 270°C. Similar to PBT, PEF is an ideal carrier for coloring PET. Due to its low melting point, the PEF carrier has the potential to release additives or colorants early and thus distribute them evenly throughout the material or material mixture to be colored.

[0074] Due to the compatibility of the PEF carrier with polyesters, and especially with PET, the mixing and distribution of PEF in polyesters, and especially in PET, is very good. Other plastics that do not dissolve well in polyesters, such as PET, also disperse poorly and can therefore cloud the material or material mixture to be colored, such as PET.

[0075] For example, in an extruder or during plasticizing, the PEF reacts with the PET to be colored, forming heat-stable copolymers. Due to their heat resistance, these PET-PEF copolymers do not produce undesirable degradation products during mechanical recycling and therefore do not cause yellowing or clouding of the finished plastic product. The PET-PEF copolymer degrades in the SSP (Solid State Polycondensation) reactors, during drying, and in the extruder, just like pure PET, and does not cause any disruption. During copolymerization, the PEF carrier virtually disappears and is completely absorbed into the PET matrix.

[0076] In chemical recycling, the oligomers or monomers formed from the PET-PEF copolymers are not chain terminators.

[0077] In packaging or textile applications, PEF is not seen as a contaminant, but rather as an added value, as PEF has much better barrier properties and mechanical parameters than PET itself.

[0078] There is therefore no reason to separate the PEF or prevent its accumulation in PET recycling.

[0079] If the carrier in the color masterbatch consists solely of PEF (and no other plastics), the recyclability of other polyesters, and especially PET, improves in that more carrier material can be incorporated during coloring, either once or repeatedly, especially when coloring recycled material such as rPET, without increasing the accumulation of substances considered contaminants in the colored end product. A masterbatch consisting solely of PEF and colorant can thus prevent the accumulation of contaminants such as PBT, ensuring that the colored material remains recyclable.

[0080] Unlike BPT and PET themselves, PEF is usually made from 100% biological sources and not from petroleum.

[0081] PEF-based masterbatches contain much less water or moisture than, for example, PET- or PBT-based masterbatches. Since water molecules generally tend to hydrolyze polyester, a lower water input via PEF carriers is advantageous compared to other carrier materials.

Claims

Patent claims 1. A method for coloring polyester, such as PET, suitable for the production of (stretchable blow molding) preforms, comprising at least the following process steps, (a) providing a first component consisting substantially of one or more polyesters and / or a polyester recyclate, (b) provide a second component, (c) mixing, shearing and melting the two components, characterized in that the second component consists of at least one PEF containing a colouring agent.

2. The method according to claim 1, characterized in that the one or more polyesters and the polyester recyclate of the first component, insofar as it is present, consist essentially of PET.

3. Method according to claim 1 or 2 characterized in that the first component consists essentially of recycled polyester, in particular recycled PET.

4. Method according to one of the preceding claims 2 or 3, characterized in that the PET or PET recyclate of the first component is modified with copolymers and / or with diethylene glycol and / or isophthalic acid.

5. Method according to one of the preceding claims, characterized in that the proportion of the second component is 0.01 to 15 percent by weight of the sum of the first and second components.

6. Method according to one of the preceding claims characterized in that the mixing, shearing and melting of the two components leads to a coloring or colour of the resulting plastic mixture which differs from the coloring or colour of the first component.

7. Method according to one of the preceding claims characterized in that the second component or the PEF contained therein has a melting point 15°C or more than 15°C lower than the first component, or particularly preferably that the second component or the PEF contained therein has a melting point 15°C to 20°C lower than the first component. Method for producing a preform and for optionally further processing the preform into a hollow body, such as a bottle or a container, made of polyester, in particular PET, comprising the method for coloring polyester, according to one of the preceding claims, further comprising the process step (d) forming a preform from the colored polyester, e.g. by injection molding, and optionally the process step (e) Forming a hollow body from the preform by stretch blow molding. Masterbatch composition for coloring polyesters, in particular recycled polyester, such as PET or, in particular, rPET, for preforms that substantially comprise a masterbatch composition PEF combined with a colorant. Method or masterbatch composition according to any one of the preceding claims, characterized in that the PEF constitutes at least 30 wt.% of the second component or the masterbatch composition. Method or masterbatch composition according to any one of the preceding claims, characterized in that the water content of the second component or the masterbatch composition is a maximum of 0.04 wt.% based on the second component or the masterbatch composition.A process or masterbatch composition according to any one of the preceding claims, characterized in that the colorant is selected from a group consisting of pigments, dyes, and / or combinations thereof. A process or masterbatch composition according to claim 12, characterized in that the pigments comprise or consist of colored particles, wherein the pigments are preferably pre-milled to a size in the range of 200 nm to 400 nm. A process or masterbatch composition according to claim 12 or 13, characterized in that the pigments are selected from a group consisting of iron oxides, titanium oxide, and mica, wherein these pigments are preferably in crystalline form and / or may optionally be coated. A process or masterbatch composition according to the preceding claim 14, characterized in that the pigments are coated with inorganic or organic oil. A process or masterbatch composition according to any of the preceding claims, characterized in that at least titanium dioxide pigment is selected as the colorant, wherein the titanium dioxide is preferably present as rutile crystals to a weight of over 90%. A process or masterbatch composition according to any one of the preceding claims 12 to 16, characterized in that the dyes are selected from a group consisting of 2-(2-quinolyl)-1,3-indandione, 2-(3-Hydroxyquinolin-2-yl)-1H-indene-1,3(2H)-dione, 1,4-bis(butylamino)anthracene-9,10-dione, 1,4-bis(mesitylamino)anthraquinone, 1-[(1-methylethyl)amino]anthraquinone, and 8,9,10,11-tetrachloro-12H-phthaloperin-12-one and combinations thereof.A process or masterbatch composition according to any one of the preceding claims, characterized in that the colorant charge in the second component or in the masterbatch composition is in the range of 0.01 wt.% to 70 wt.%, preferably 5 wt.% to 70 wt.%, more preferably 20 wt.% to 70 wt.%, more preferably 35 wt.% to 70 wt.%, more preferably 40 wt.% to 70 wt.% of the second component or the masterbatch composition. A process or masterbatch composition according to any one of the preceding claims, characterized in that… - that, if the colouring agent contains colouring agent, the colouring agent constitutes a maximum of 20% by weight of the second component or the masterbatch composition, or - that, if the colorant consists of dye (i.e., no additional pigments are present), the charge of colorant is in the range of 0.01 wt.% to 20 wt.%, more preferably in the range of 5 wt.% to 20 wt.% of the second component or the masterbatch composition. A process or masterbatch composition according to any of the preceding claims, wherein the masterbatch composition contains further active substances, in particular from the group consisting of acetaldehyde scavenger, oxygen scavenger, IR absorber, UV absorber, and lubricant. Masterbatch for coloring polyesters, in particular recycled polyester, such as PET or especially rPET, for preforms, comprising a composition according to claim 9.