Heat Seal Coating Formulations for Food Packaging Applications

The integrity of a package must be maintained by a material that can be heat sealed, particularly in medical, food, and pharmaceutical packaging applications. Obtaining an appropriate heat seal in packaging is crucial since, compared to package failure, heat seal failure is a more common reason for product degradation. Material selection and packaging methods should be evaluated carefully to choose the proper material that can effectively function under proper conditions. Hermetic seal property ensures the effectiveness of barrier layers in preventing oxygen permeation, loss of odor, and transmission of water vapor. Polylactic acid (PLA) is one of the biodegradable polymers with the greatest potential for heat sealing and thermal processing. To establish manufacturing protocols, verify seal effectiveness, and ensure product integrity, it is essential to consider the effects of controlling process parameters during package design. Therefore, to undercover the role of PLA structure on its properties, the factors impacting its heat-sealing feature are elaborated on in this chapter. More... Read More

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Sealing is one of the most important process steps in industrial packaging, because the sealed seam is the most sensitive section of a package in terms of quality. For this reason, a major focus in flexible packaging is the sealing process, and among this, heat sealing is the most frequently used technology. In detail, applications of heat sealing processes are confronted with four conflicting objectives: increasing seam quality, reducing dwell time, reducing sealing temperature, and increasing process robustness towards varying conditions. Typical problems, such as identification of the optimum process parameters or selection of the most appropriate packaging film, are subject to these conflicting objectives. This paper presents a recently published design of experiments for characterizing and comparing heat sealing properties of packaging films based on a multi-objective optimization algorithm. The approach provides easy-to-read charts showing all optimum sealing parameters with regard to the four essential objectives of heat sealing: seam quality, dwell time, sealing temperature, ... Read More

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The book explains concept and principle of heat sealing and the correlation between molecular properties and seal performance. First, theoretical aspects of heat sealing and the mechanism involved in seal formation are discussed. Then different test methods for evaluating seal and hot tack performance and quality are reviewed. Different common sealant materials in fl exible packaging are discussed including multiphase and bioplastic sealants. Effect of processing condition and material characteristics on seal and hot tack performance of sealant materials are reviewed. Mathematical models are presented as powerful tools to optimize sealing condition in order to balance production cost and seal properties. Finally, practical examples of sealant design are introduced in food and industrial packaging.

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Freudenberg Sealing Technologies (FST) continues to add products to its portfolio that are certified to meet the latest regulatory requirements for food-contact materials and address the temperature, media resistance and cleaning-in-place and sterilisation-in-place (CIP/SIP) needs prevalent in the food sector.

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Condition of heat seal region in flexible food packaging is decisive to preserve food quality along the shelf life. The main process parameters of heat sealing, naming time, temperature, and pressure are adjusted by manufacturers based on the characteristics of the film being used. Nonetheless, issues with seal integrity are still encountered. This thesis aims to understand the mechanisms that lead to problems in the heat sealing process of flexible packaging and to identify ways of preventing seal integrity issues. It explores various factors that can impact the quality of heat seal in different types of conventional flexible films. The research findings indicate that there are many different material properties, process parameters, contaminants, and future processes that can contribute to the formation of gaps and micro-leakages in the seal area, and these parameters can be interrelated. To understand the relationships between these parameters and their impact on the leak formation, some chosen parameters such as contaminant food particles, film tension, melt flow index (MFI), seal... Read More

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Abstract Flexible packaging has many advantages in the food industry, arising from low weight, formability, multilayer complexity and cost. Heat sealing is a very efficient technique to close flexible food packaging. Currently, many thermoplastic materials are used in seal layers. A seal can be formed when these materials are heated and brought into contact; thereafter, polymer chains diffuse across the seal interface and entangle. Hydrogen bonds, polar and ionic interactions are molecular forces that can come into play, depending on the thermoplastic materials that are used in the seal layer. Bonds between identical polymers, referred to as autohesion, are formed in pouch applications (e.g., horizontal and vertical formfillseal packages). In lidding applications, the flexible film is sealed to a rigid cup, tray or bottle, whereby bonds can be formed between nonidentical polymers because the materials are often provided by different suppliers. All heat seal technologies imply heating of seal layers but differ in the heating principle. In the food industry and in most scientific se... Read More

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Heat sealing is one of the primary unit operations of flexible packaging. In this chapter heat sealing is described from a science and engineering perspective: why it is important, how to measure it, and factors that influence performance, as well as the scientific fundamentals of heat sealing with an eye toward understanding how to troubleshoot heat seal issues. The technology of easy-open seals and reclosable technology is described. Hot bar heat sealing, the predominant method used in flexible packaging, is the focus but ultrasonic sealing is introduced. The chapter ends with a comparison of sealant attributes that may be important for selecting one sealant over another for a specific application.

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Sealing is a critical step in different packaging industries. In heat sealing as one of the major types of sealing processes, two layers of materials (typically thermoplastics) are joined together through the application of heat and pressure load for a certain sealing time. Due to the capabilities of the heatsealing process to seal different kinds and sizes of packages, it has a wide range of applications in many different industries such as the packaging of food and medical products. The quality and integrity of sealings produced by these techniques are crucial for the quality and safety of the contained materials. In this paper, different types and processes of sealing are discussed. Due to the variations in shape, size, and complexity of the sealing region, quality testing and inspection of these products is a challenging task. Nondestructive testing and evaluation (NDTE) techniques can be promising tools to overcome these challenges. Furthermore, a detailed study of various types of potential defects and their generation mechanism in heat sealing is presented. Then, various type... Read More

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This chapter describes all of the packaging options for thermally processed foods. Details of the materials used to make the packaging as well as the method of packaging manufacture are described. The chapter covers making and use of tinplate cans, and discusses prevention of corrosion. Glass manufacture is described and advice to prevent cracking is given. Finally, all of the options of packaging using plastic materials and laminates are given, and processing and handling recommendations are described.

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Abstract Seal area represents the most problematic part in food packaging for controlling the moisture and gas ingress and preserving product quality. Understanding the mechanism of heat sealing, which is a widely used method in flexible packaging, is critical for maintaining product quality throughout the storage and preventing food waste. Likewise, understanding the factors causing the leak formation in the seal interface helps to avoid failures and increase integrity for all seal types produced by heat sealing methods. This review looks at heat sealing and its mechanisms in flexible food packaging materials and particularly focuses on the reasons behind the encountered seal integrity problems that have a detrimental effect on food quality and shelf life. Heat sealing mechanisms, form fill seal systems and seal types were analyzed. Then, factors affecting the leak formation have been grouped as process parameters, material properties, contaminants, and further processes, which is uncharted territory in open literature. Finally, the details of these groups and their interrelationshi... Read More

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Abstract Heat sealing is one of the most common techniques for sealing food packages. In this study, the effects of sealer parameters such as dwell time (0.52 s), jaw temperature (225250C) and pressure (69345 KPa) and the seal contaminants (coffee particles [0.700.85 mm]) were studied on polymer materials used in coffee capsules: (1) lidding, poly(ethylene terephthalate) (PET)/Al/linear lowdensity poly(ethylene) (LLDPE); (2) wall, polystyrene (PS)/ethylenevinyl alcohol copolymer (EVOH)/PS; and nonwoven filter, NW1 (monocomponent fibre) or NW2 (bicomponent fibre [core/sheath]). The presence of NW1 and NW2 nonwoven in the seal structures decreased the interfacial temperature by 5C and 11C, respectively in comparison to seal structures without nonwoven. The degradation of the seal bonding caused a decline in the seal strength at elevated temperature (NW: >240C without NW: >235C) and longer dwell time (NW: >1 s, without NW: >1.5 s). The core and sheath structure of NW2 (969 N/mm) was responsible for higher seal strength in comparison to NW1 and without NW, as t... Read More

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Seal strength is a key indicator of heat seal quality in flexible packaging. In this study, the effect of seal bar geometry, material composition and food particle contamination on the seal strength of widely used lowdensity polyethylene (LDPE)based compound films was examined. Additionally, the maximum level of allowable solid food particle contamination was determined for ground coffee particles and powdered sugar. The results showed that adding metallocene LLDPE compound decreases seal initiation temperature (SIT) and increases overall seal strength. Also, changing seal bar geometry from flat to grooved bar with 0.56mm pitch height enhanced the seal strength significantly. Moreover, pressure mapping and Tpeel tests at SIT pointed out that grooved bars alter the pressure distribution and first contact points through the seal surface. Contamination of ground coffee particles at the seal interface as occurs during the packaging process when a powdery product is dropped in a package did not affect the seal strength up to 10 g/m 2 at 0.5s dwell time. Above that amount, seal streng... Read More

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For thermal preservation of food, various types of retail polymeric packaging can be used: rigid, semi-rigid, flexible, and other kinds of containers. To make polymeric (plastic) containers usable for thermal sterilisation, and to ensure long storage of food, they should have a barrier layer that will make them heat-resistant, prevent oxygen ingress, and preserve the products quality and nutritive value. Every polymer material has its individual heat resistance characteristics. This paper considers such retail containers for food packaging as a composite can made of metal with a plastic lid and a semi-rigid heat-resistant polymer container with a foil cover. When using different container types for heat sterilisation and prevention of physical defects in cans, the following technological characteristics of cans should be taken into account: closure strength, depressurisation pressure, method of closure, diameter of a containers opening, absence or presence of a stiffness relief on the cover, temperature of packaging, and other factors. The research includes analysis of existing typ... Read More

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This chapter provides a basic grounding in the principles of sealing a product inside a package. It includes the principles of making a seal using heat, ultrasonic energy and other sealing systems such as cold sealing using adhesives. The chapter includes considerations of the chemistry of the materials being sealed together and how the sealing system must be designed and operated in a way that is compatible with the physical and chemical properties of the materials and also the product to be packaged. It provides an overview of the various packaging system options available in the food industry such as bag making, pouch sealing, tray sealing, flow wrapping and form fill seal systems. The chapter also reviews the industry sectors that routinely use sealing technologies in their packaging processes-pharmaceuticals, food and other consumer products and their need for pack security, shelf life extension and product protection from contamination and loss.

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Heat sealing is one of the primary unit operations of flexible packaging. In this chapter, heat sealing is described from a science and engineering perspective: why it is important, how to measure it, and factors that influence performance, as well as the scientific fundamentals of heat sealing with an eye toward understanding how to troubleshoot heat seal issues. The technology of easy-open seals and reclosable technology is described. Hot bar heat sealing, the most common method used in flexible packaging, is the focus but ultrasonic sealing is introduced. This chapter ends with a comparison of sealant attributes that may be important for selecting one sealant over another for a specific application.

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