When to Use Cpet Film？

Polyethylene terephthalate (PET) has been used in the beverage industry for many years, largely replacing other materials as the most common type of plastic in packaging materials worldwide.

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C-PET (crystallisable PET) shrink film can be used for shrink sleeve labelling. CPET shrink sleeve label film is made from sustainable, 100% recyclable PET bottles. CPET shrink sleeve label film has a high lateral shrinkage rate and is recommended for use in steam ovens.

CPET Shrink Sleeve Label Film

In view of the growing demand for the reuse of packaging materials, PET bottles are increasingly made from post-consumer recycled materials, and a number of bottles made from 100 per cent recycled PET materials are already on the market. The development of "ultra-clean technologies" capable of effectively removing molecular contaminants has been a major boost in this regard. This is a prerequisite for the reuse of recycled materials in food applications such as PET bottle recycling.

The global product decoration and branding market is expected to witness significant growth due to the ability of shrink sleeves to fully decorate bottles, cups, trays and various other packaging types from top to bottom in 360°.

As a result, shrink sleeves help reduce the need for large quantities of coloured bottles. This helps to improve the quality of recycled bottle materials and supports the wider use of recycled materials.

CPET Shrink Sleeve Label Film

Shrink sleeve offers an effective labelling technology that combines high quality graphics with complex container geometries to maximise the shelf appeal of fast moving consumer goods (FMCG) products.

In terms of volume, PETC is currently the most used shrink sleeve label film type in Europe and North America, largely replacing PVC and polystyrene based shrink sleeves.

Washable shrink sleeve films printed with specially developed washable ink and primer solutions are based on crystallisable PET (cPET). This approach represents a significant upgrade to the existing PET bottle recycling process, as cPET shrink sleeves can be fully recycled along with the bottle flakes, contributing to higher yields and quality of rPET.

CPET Shrink Sleeve Label Film

Advanced external and internal analytical tests have confirmed that the deinking process does not have any impact on the quality of the recovered PET recyclate and is safe for use in PET bottle recycling processes requiring food-grade rPET quality.

It has long been the case that when recycling PET containers labelled with full-body shrink sleeves, the shrink sleeve material must be completely removed from the PET bottle recycling stream to avoid subsequent processing of the recycled PET due to material incompatibility.

CPET Shrink Sleeve Label Film

While brand owners are striving to achieve 100% recyclability of their packaging materials, the current PETG shrink sleeve is considered an interfering factor in PET bottle recycling and must be removed from the PET bottle recycling stream. Given the trend towards thinner-walled PET bottles, this situation is made even more problematic because the quantitative mechanical separation of shrink sleeves also leads to increased loss of PET bottle recycling material during the separation process.

In order to avoid material separation and thus increase the yield and quality of rPET, crystallisable PET (cPET) was developed as a technical alternative to PETG. Unlike PETG, crystallisable PET is compatible with the PET bottle recycling stream and does not adversely affect the quality of rPET, making it possible to recycle both bottle PET and cPET shrink tubing.

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Compliance with FCM legislation

Beverage companies that use PET bottles with recycled content for their products have to prove compliance with the European food contact material (FCM) legislations. These are the general requirements of the European “Framework Regulation” (EC) No / and the “Plastic Regulation” (EU) No 10/ as well as the demands of the “Recycled Plastic Regulation” (EC) No 282/. According to these regulations, several criteria must be met: no harm to human health, the Overall Migration Limit (OML) requirement of 10 mg/m2 of food contact area has to be met and (if applicable) the Specific Migration Limits (SMLs) as well as the safety requirements regarding Non-Intentionally Added Substances (NIAS) have to be fulfilled. Moreover, the process for the production of recycled PET needs to have received an EFSA opinion in favor of authorization[2].

Food-safety aspects of the bottle-to-bottle PET recycling process

It is essential to ensure that any substances migrating from the packaging material into the food do not harm the consumer. In the case of printed and deinked crystallizable PET shrink sleeve labels, which are recycled together with the PET bottles, an analytical screening after washing and the “super clean process” must be done to demonstrate the safety of the process. In this context, particular attention must be paid to the presence of any NIAS that still might be present in the recyclate and which could originate from the PET bottles as well as from other materials like printing inks. NIAS are chemical substances that, in contrast to IAS, are present in a packaging material but have not been added intentionally during the production process. NIAS can be by-products or impurities of starting substances as well as reaction or decomposition products. In the case of PET beverage bottles some NIAS are related to degradation or reaction side-products of additives or the polymer itself. Additionally, PET oligomers can be considered as NIAS either[1].

Samples and sample preparation

The main objective of this study was to confirm that there are no food safety risks regarding washable inks used on crystallizable PET shrink labels within a bottle-to-bottle recycling process. Against this background four PET recyclate samples, based on combined recycling of PET-bottles/printed cPET shrink sleeves, were analyzed in comparison to reference PET-bottles/unprinted cPET shrink sleeve samples, to determine the presence of NIAS after hot washing to remove the printing ink, and a “super clean process” to remove potential migrants.

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Sample description

All samples (including the reference) had been hot-washed applying typical conditions used in the PET industry and after drying decontaminated via a “super-clean process”. In each case a ratio of 97/3 PET/cPET had been used as input material which represents a typical ratio of bottle to sleeve material.

Flow chart

Fraunhofer IVV results: Non-target screening of volatile compounds[5]

Each sample (in duplicate) was analyzed using headspace gas chromatography with flame ionization detection (FID).

All investigated samples were found to contain the typical PET degradation products acetaldehyde (CAS 75-07-0) and 2-methyl-1,3-dioxolane (CAS 497-26-7). In addition, traces of benzene (CAS 71-43-2) as well as the residual monomer ethylene glycol (CAS 107-21-1) were detected. It has to be pointed out, that benzene is most probably a degradation product from PVC impurities in the PET recycling stream and is present in trace amounts in all bottles with recycled content[2]. No substances resulting from the printing ink could be detected in the samples.

Table 1: Quantification of volatile substances in the investigated sample. Concentrations are given as mg/kg PET; *The results of these quantification are only single values, therefore no standard deviation can be given.

Fraunhofer IVV results: Non-target screening of semi-volatile compounds[5]

Each sample was extracted with dichloromethane by total immersion. These extraction solutions were analyzed by gas chromatography with flame ionization detection (GC-FID). The findings were that only PET typical oligomers, e.g. cyclic PET trimer (C30H24O12) up to cyclic PET hexamer (C60H48O24), were present whereas no substances resulting from the printing ink could be detected in the samples.

Fraunhofer IVV results: Targeted analysis of inorganic compounds, bisphenol A, phthalates and adipates[5]

Traces of these substances could be detected, but only in very low concentrations which are comparable to standard samples of recycled PET.

Bisphenol A as well as phthalate and adipate esters might be from ubiquitous sources whereas DEHP, DINP and DIDP can be used as technical support agents.

Migration modeling[2,3,4]

Migration research has shown that migration from the packaging material to food obeys Fick’s laws of diffusion and is therefore predictable and can be calculated using suitable software and appropriate, scientifically-based modeling parameters.

Migration is dependent on the molecular weight (or rather the molecular volume) of the migrant. Figure 1-6 show a correlation between the bottle wall concentration, which corresponds to a migration of 10 µg/kg (10 ppb) food after storage for 365 days at 25 °C and the molecular volume of the migrant (green curve). These concentrations were calculated for a PET container with a surface-volume ratio of 6 dm2 per 1 kg food, the so called “EU-cube”. As an additional safety factor, a deviation of 20 % on the molecular volume was considered (red line). The red dots in the assorted diagrams represent the concentration of the substances in each sample, which were detected in the above described screening tests.

It can be seen, that all of the experimental dots, except acetaldehyde and ethylene glycol, are well below the 10 µg/l curve, which is the migration limit for non-evaluated substances (provided that they are not classified as ‘mutagenic’, ‘carcinogenic’ or ‘toxic to reproduction’). This means, that the migration of these substances will be below 10 ppb after a storage time of 1 year at 25 °C.

Fig. 1: Sample Ref_flake / Fig. 2: Sample LMUV_flake

Fig. 3: Sample Ref_pellet / Fig. 4: Sample LMUV_pellet

Fig. 5: Sample StdUV_pellet / Fig. 6: Sample SB_pellet

Figure 1-6[5]: Correlation between the bottle wall concentration which corresponds to a migration of 10 µg/kg food after storage for 365 days at 25 °C and the molecular volume of the migrant.

green line: predicted from molecular volume; red line: deviation of -20% on the molecular volume V (worst-case).

red dots: experimental data points of the different samples.

Acetaldehyde (FCM substance No 128) and ethylene glycol (FCM substance No 227) are listed in the Annex I of the Regulation 10/ with specific migration limits of 6 mg/kg and 30 mg/kg, respectively. Therefore, the above mentioned specific migration limits can be applied for these substances instead of 10 ppb.

Siegwerk analysis results

All six samples had also been analyzed by Siegwerk in a targeted analysis for printing ink components after an extraction in Ethanol for 3 days at ambient temperatures via GC/MS or LC/HRMS respectively. Additionally, as a comparison, a sample of a printed sleeve (which hadn´t been hot-washed, deinked and decontaminated) with the printing structure of LMUV_flake was analyzed. No printing ink ingredients could be detected in any of the samples that were originally printed either with one of the UV inks (LMUV_flakes, LMUV_pellet, StdUV_pellet) or the solvent-based ink (SB_pellets) by a detection limit of 1 ppm for most of the smaller molecules (MG < 240 g/mol) and 0.5 ppm for the others. On the other hand, all ink-related substances present in the printing structure printed with the LMUV-ink (LMUV_flakes) could be detected in the comparison sample of the printed sleeve. This clearly shows the efficiency of the washing and decontamination process.

In the extract analysis of the sample with the solvent-based printing ink structure (SB_flakes) only a few substances could be detected, namely Oleamide (CAS 301-02-0) and DOA (CAS 103-23-1)) but the concentration of these compounds was comparable to the unprinted sample (Ref_flakes). This indicates that these substances were present in the rPET substrate either. This assumption is further strengthened by the fact that no other printing ink specific substances such as paraffin waxes (CAS -74-2) or trimethylolpropane (CAS 77-99-6) could be found. As Oleamide and DOA are listed in the Annex I of the Regulation 10/ as well with high migration limits of 60 mg/kg (OML) and 18 mg/kg, respectively, these substances are of no toxicological concern, even if they had been detected.

[5]: Test report Fraunhofer IVV: Screening analysis of non-intentionally added substances (NIAS) in PET, January . Proprietary of Siegwerk, Klöckner Pentaplast and Multi-Color Corporation

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