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  • Plastics in paper packaging

    Plastics in paper packaging

    Part 2: Important coating polymers

    In the first part of our series on plastic content in paper-based packaging for food and consumer goods, we focused on the reasons for using plastic layers and typical functional requirements – without going into specific types of polymers. In part 2, we now turn our attention to individual, sometimes specialised plastic materials and plastic substitutes that are used specifically to achieve certain functional properties. We look not only at conventional plastics, but also at bio-based and alternative materials that are important in terms of barrier effect, sealability and surface protection, as well as from an environmental and regulatory perspective. Our focus is on plastics in paper packaging: from PE to bio-based polyesters – an overview of functions, environmental aspects and regulatory requirements.

    Polyethylene (PE) 

    Polyethylene is the plastic most commonly used in paper-based packaging, usually applied as a thin coating on cardboard or paper. It primarily serves as a moisture and grease barrier, ensuring that liquids or oils do not penetrate the paper fibres. At the same time, PE’s thermoplastic properties enable reliable sealability, which is particularly important for bags, cups and food cartons. PE is chemically inert, food-safe and relatively inexpensive, which explains its widespread use. From an environmental point of view, however, it is problematic because it can only be separated from the fibre material in paper recycling through complex processes and remains persistent in nature. More recycling-friendly variants, such as thinner coatings or modified PE types, are currently being developed to improve the recyclability of paper-PE composites.

    Styrene acrylate copolymers 

    Styrene acrylate copolymers combine the properties of styrene and acrylic acid esters. In paper-based packaging, they are primarily used as binders in barrier or protective coatings, where they provide adhesion, mechanical stability and water resistance. They are also found in certain adhesives and printing inks, where they contribute to a robust, durable surface.

    Acrylate polymers 

    Acrylate polymers (pure acrylates) are frequently used in adhesives for labels and packaging tapes. They are characterised by strong adhesion, UV and moisture resistance, and temperature stability. In addition to adhesives, acrylates are also used as transparent coatings on films or paper to improve barrier properties against gases and aromas without compromising printability or optical quality.

    Polysiloxanes

    Polysiloxanes, also known as silicones, are primarily used in packaging as ultra-thin coatings or additives. For example, they serve as a non-stick or release layer on paper substrates, such as label backing papers, so that adhesive surfaces can be easily removed. When added in small quantities, polysiloxanes also improve the processability and lubricity of coatings, such as in the coating of paper. Due to their temperature and chemical resistance, they are suitable for many food contact applications.

    Polyhydroxybutyrate (PHB) 

    PHB belongs to the family of bio-based polyhydroxyalkanoates (PHA) and is produced by microorganisms from renewable raw materials. It is completely biodegradable and can replace polypropylene in certain applications. PHB is rigid, dimensionally stable and suitable for direct food contact, but it is more brittle and heat-sensitive than many conventional plastics. In paper composites, it can serve as a coating or film layer, especially in compostable disposable packaging.

    Bio-based polyesters 

    Bio-based polyesters comprise a range of materials that are made entirely or partially from renewable raw materials. A well-known example is polylactic acid (PLA), which is compostable under industrial conditions and is used in the form of films, trays or paper coatings. Other bio-based polyesters include PEF, which can replace PET, and PBS or PBAT, which are used for compostable films and bags. These materials offer potential for reducing fossil raw materials, but face challenges such as limited heat resistance or limited recycling infrastructure.

    Conclusion 

    The materials presented, which are not an exhaustive list, complement the range of functional plastics in paper-based packaging and demonstrate the wide variety of options available for achieving specific properties such as barrier effect, sealability or surface protection. Their choice depends heavily on technical requirements, regulatory compliance and environmental goals – an area that is likely to become even more dynamic in the coming years.

    Coating Properties Production volume (rough estimate)
    Polyethylene (PE) Moisture and grease barrier, thermoplastic, food-safe, cost-effective6 million tonnes
    Styrol-Acrylat-Copolymers Adhesion, mechanical stability, water resistance, in adhesives and printing inks1.5 million tonnes
    AcrylatpolymersStrong adhesion, UV and moisture resistance, temperature stability2 million tonnes
    Polysiloxanes Non-stick or release coating, temperature and chemical resistance500,000 tonnes
    Polyhydroxybutyrate (PHB) Biodegradable, rigid, dimensionally stable, suitable for food contact 200,000 tonnes
    Bio-based polyesters Compostable, reduction in fossil raw materials, limited heat resistance300,000 tonnes

    List of sources for research on the various coatings used on paper:

    1. Packoi. “PE Coated Paper.” Access on 3 September 2025. [https://packoi.com/de/blog/pe-coated-paper/](https://packoi.com/de/blog/pe-coated-paper/). 
    1. Siegwerk Druckfarben AG & Co. KGaA. “Paper Coating Guide.” Access on 3 September 2025. [https://www.siegwerk.com/fileadmin/Data/Documents/Publications/Flyer/210_297_4C_SW_Flyer_PaperCoatingGuide_DE_Final.pdf] (https://www.siegwerk.com/fileadmin/Data/Documents/Publications/Flyer/210_297_4C_SW_Flyer_PaperCoatingGuide_DE_Final.pdf).
    1. Guyenne Paper. “Coating: What is it?” Access on 3 September 2025. [https://www.guyennepapier.com/de/blog/detail/beschichtung-was-ist-das/](https://www.guyennepapier.com/de/blog/detail/beschichtung-was-ist-das/).

    Author: Dr. Daniel Wachtendorf, Innoform GmbH August 2025

  • Practical testing of water vapour permeability – which method makes sense when

    Practical testing of water vapour permeability – which method makes sense when

    Practical testing of water vapour permeability – which method makes sense when

    The Water / Moisture Vapour Transmission Rate (WVTR) is a key parameter for the durability, functionality and sustainability of flexible packaging. Innoform Testservice offers three recognised laboratory methods that together cover the entire practical range from breathable bags to high-barrier films. Below you can find out which test principle has proven itself in which application scenarios.

    1 Electrolytic / hydrolysis sensor (ISO 15106-3)

    Standards: DIN EN ISO 15106-3
    Area of application:

    • High-barrier films, metallised or inorganically coated structures
    • WVTR from 0.01 g – m-² – d-¹ to approx. 100 g – m-² – d-¹
    • Moulded packaging (pouches, bottles, pharmaceutical primary packaging)

    Why choose?
    The phosphorus pentoxide (or calcium chloride) sensor system decomposes incoming water vapour electrolytically; the required current is directly proportional to the permeate. As a result, the method achieves very low detection limits and is suitable for premium barrier and shelf-life studies. Innoform offers the same technology for both flat films and complete packaging chambers.

    2 Modulated infrared sensor (ASTM F 1249 / ISO 15106-2)

    Normen: ASTM F 1249, DIN EN ISO 15106-2
    Einsatzbereich:

    • Typical packaging barriers (≈ 0.05 – 50 g – m-² – d-¹)
    • Fast incoming goods and process control (results ≤ 2 h)
    • Temperature and RH-controlled tests for validation studies

    Why choose?
    A modulated infrared detector measures the water vapour absorption in the carrier gas behind the sample. The method delivers reproducible results with short analysis times and automatic climate control – ideal for series testing and comparative material benchmarking.

    3 Gravimetric cup method

    Standards: DIN 53122-1, DIN EN ISO 12572, ASTM E 96
    Area of application:

    • Medium to high WVTR values (≈ 1 – 1000 g – m-² – d-¹)
    • Straight, flat samples ≥ 50 cm²
    • Quality control for standard laminates, paper/plastic composites, breathable construction films

    Why choose?
    The cup method is robust, inexpensive and widely recognised in standards. It measures the actual mass loss and is therefore ideal as a reference or for comparative measurements between laboratories. The disadvantages are longer measurement times (hours to days) and limited sensitivity for high-quality barrier films.

    4 Decision-making aid at a glance

    RequirementTypical WVTRSampleRecommended Innoform methodComment
    Budget-friendly reference, standard-compliant> 0,5 g · m⁻² · d⁻¹≥ DIN A5 filmCup gravimetricslow, very robust
    Fast QC measurement in production0,05 – 50Foil or flat moulded partIR sensorResultate ≤ 2 h
    High barrier, food/pharmaceuticals0,01 – 0,05Foil or packElectrolyticHighest sensitivity

    5 Practical recommendations

    1. Sample conditioning – at least 24 h under test climate to harmonise moisture gradients.
    2. Double measurement – Innoform carries out two determinations as standard in order to recognise outliers at an early stage.
    3. Order reference foils at the same time – have a known barrier tested once a year; this way you can keep an eye on the calibration in the long term.
    4. Select test climate – typically 23 °C / 85 % rH for food packaging, 38 °C / 90 % rH for tropical simulation.

    Complete table of WVTR test methods for films & packaging

    Test methodImportant standardsTypical WVTR range (g – m-² – d-¹)Special featuresInnoform
    for Flexpack usual
    Gravimetric (cup: dry / wet)DIN 53122-1, ASTM E 96, ISO 125720,5 – 1000favourable, reference✔
    Capacitive humidity sensorISO 15106-10,05 – 1000fast QC, medium sensitivity✖
    Modulated IR sensorASTM F 1249, ISO 15106-20,02 – 100automated, ±2 h Result✔
    Electrolytic / hydrolysis sensorISO 15106-3, ASTM F 26220,005 – 0,05High barrier, moulded packs✔
    Calcium corrosion test(R&D, DIN SPEC in progress)- (R&D, DIN SPEC in progress)10⁻⁴ – 10⁻⁶Ultra-OLED barriers✖
    Optical-electrical hybrid calcium–< 10⁻⁶Combined measurement for photovoltaics✖

    Summary
    Whether standard laminate or high-tech barrier layer: Innoform’s gravimetric, IR and electrolytic processes cover practically every WVTR window of practical relevance. The choice depends on your target WVTR, the time window and the sample geometry – and ultimately determines how reliable your shelf life and process data are.

    You can find the Innoform tests and contact persons here:

    WVTR Prüfungen
  • Precise evaluation of weather resistance

    Precise evaluation of weather resistance

    Q-UV artificial weathering of films and papers helps evaluate weather resistance.

    Overall purpose

    Artificial weathering is an indispensable method for evaluating the long-term durability and weather resistance of plastics. With the help of modern testing devices, such as the Q-UV device, damage caused by UV radiation and moisture can be simulated in a targeted manner. Standardised procedures according to DIN EN ISO 4892-3 and DIN EN 14932 allow realistic ageing processes to be efficiently reproduced. This method provides important insights, particularly for applications in the construction, automotive and agricultural industries. The results are a significant aid to product development and quality assurance.

    Test methods to proof the weather resistance

    Artificial weathering of plastics is an essential part of materials testing focused on weather resistance. It is used to assess the long-term durability of materials when exposed to UV radiation, humidity and temperature. While test methods using xenon arc lamps simulate a broad light spectrum, UV fluorescent lamps enable targeted investigations in the short-wave UV range.

    With the addition of a Q-UV device, tests can now be carried out in accordance with DIN EN ISO 4892-3 and DIN EN 14932. These standards define test methods for assessing the artificial weathering of plastics with UV radiation and moisture. This greatly affects weather resistance. The procedure is particularly relevant for applications in which plastics are exposed to intense solar radiation. These applications include the building industry, the automotive industry, and especially in agriculture.

    The Q-UV tester simulates the damaging effect of UV light and moisture by cyclically exposing the samples. UV fluorescent lamps that emit in defined wavelength ranges are used. Radiation in the UV range has a high energy density and is capable of breaking molecular bonds in plastics. This process leads to embrittlement, discolouration or a loss of mechanical properties.

    In addition to UV radiation, the sample is periodically exposed to moisture in the form of condensation or spray. This cyclical combination of radiation and moisture provides a realistic ageing simulation. It is highly relevant to various classes of materials and their weather resistance.

    Advantages and areas of application 

    • More precise ageing simulation: specific damage mechanisms can be examined through targeted UV irradiation, enhancing the assessment of weather resistance. 
    • Standardised test procedures: meets the requirements of DIN EN ISO 4892-3 and DIN EN 14932. 
    • Comparability with natural weathering tests: artificial weathering enables an accelerated evaluation. The results can be correlated with field tests, which often measure weather resistance. 
    • Wide range of applications: the method is suitable for plastics, paints, coatings and other polymeric materials.

    The addition of Q-UV to the test capabilities complements existing artificial weathering methods. It allows detailed assessment of material ageing under specific conditions. This knowledge is vital for both product development and quality assurance across a range of industries.

    Find more tests on these subjects here.

    To relevant tests
  • Innoform Online Consulting is out!

    Innoform Online Consulting is out!

    Discover our new online consulting service from Innoform Test Service!

    We are delighted to present our new online consulting service at Innoform Testservice! With this innovative service, we offer you the opportunity to access our expertise conveniently and flexibly from anywhere.

    What is the Innoform Testservice?

    Innoform Testservice is a recognised testing service provider for flexible packaging made of paper and plastic, with a special focus on the food industry, packaging manufacturers and their suppliers as well as the trade. Our modern equipment and our comprehensive knowledge of food regulations and flexpack requirements enable us to provide you with precise answers to your questions, such as

    • Food contact (conformity testing, migration tests, etc.)
    • Material characterisation (type, properties, permeation, etc.)
    • Recyclates (quality, suitability, contamination)

    Our test results and assessments are recognised by manufacturers and users of paper and plastic packaging alike and help to assess and avoid risks.

    Our new online consulting service

    With our new online consulting service, you can now get in touch with our experts directly and discuss your questions and concerns about packaging testing and optimisation. Whether you need support in selecting the right packaging material or you have specific questions about our test methods – we are here for you!

    And all without any risk. Because if you come to the conclusion that we were unable to help you sufficiently in the team meeting, there are no costs involved.

    How can you book a consulting appointment?

    Booking a consulting appointment is easy! Use our online booking service and book the next available slot directly with our experts. Our online tool shows you all available dates and automatically creates an invitation for MS teams. You do not need to be familiar with MS Teams, all you need is a browser, a microphone and speakers, which should be available everywhere these days. So here we go.

    Make an appointment

    We look forward to being able to assist you even better, faster and more competently with our new online consulting service and to answering your testing and packaging questions. Do not hesitate to contact us and benefit from our expertise!

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