by Heat Seal Coverings play a crucial role in the packaging industry by creating strong, reliable seals between packaging materials like plastic films, foils and paperboards. These specialty coatings allow for packages to remain securely sealed even when exposed to heat, pressure, moisture and other stresses during transport, storage and everyday usage. By using scientifically formulated Heat Seal Coverings, packaging manufacturers can develop versatile packaging solutions that protect products and maintain freshness.
Types of Heat Seal Coverings
There are different types of Heat Seal Coatings available depending on the substrate material and end use application. Some of the most common Heat Seal Coveringstypes include:
Low Density Polyethylene (LDPE) Coatings
LDPE coatings are one of the most widely used heat seal materials due to their versatility and economical pricing. LDPE forms strong, heat-resistant seals with substrates like polyester, polypropylene, paper and aluminum foil. It is suitable for packaging food, pharmaceutical and various consumer goods. LDPE coated films can seal within a temperature range of 120°C to 170°C providing manufacturing flexibility.
Ethylene Vinyl Acetate (EVA) Coatings
EVA is similar to LDPE but has enhanced clarity, toughness and lower sealing temperatures ranging from 95°C to 150°C depending on the vinyl acetate content. EVA forms excellent seals with itself and polyester films. It is used for packaging that requires clarity like snacks, fresh produce and medical devices. EVA seals offer high burst strength.
Polyolefin Coatings
Polyolefins like polyethylene and polypropylene are low cost polymers that provide strong heat seals. Linear low-density polyethylene (LLDPE) offers sealing temperatures close to 120°C while polypropylene seals around 160°C. Polyolefin coated films are compatible with a variety of substrates and favored for packaging food and household items.
Properties of Effective Heat Seal Coatings
For Heat Seal Coverings to create reliable seals, they must demonstrate certain important properties:
Compatibility with Substrates
The heat seal layer should be thermally compatible with the substrate film so that an efficient seal fusion occurs between the two surfaces. Successful heat sealing depends on having chemically similar polymers on either side of the seal interface.
Optimized Sealing Temperature
The Heat Seal Coveringscomposition is formulated to melt and seal within a specific temperature window. A narrow sealing range allows for consistency on high-speed packaging lines without overheating. The target seal initiation and seal strength temperatures are often 115°C to 135°C.
High Bond Strength
The formed heat seal bond should have ample peel and shear strengths to withstand stresses during distribution, stacking and normal usage conditions. Peel values greater than 1 N/mm and shear strength over 20 N/25 mm are generally desired.
Heat and Water Resistance
Packages may experience temperature fluctuations during transportation and storage. The heat seals need to maintain integrity when exposed to heat, steam, moisture and other environmental factors without delaminating or opening prematurely.
Chemical Resistance
Seals formed with Heat Seal Coverings should resist degradation when in contact with foodstuffs, preservatives, disinfectants and cleaning chemicals commonly present in packaged products and production/washup areas.
Aesthetic Appeal and Regulatory Compliance
The heat sealing surface and process should not introduce undesirable odors, flavors, or migrants into the packaged product. It must comply with food contact material approvals and regulations in target markets.
Application of Heat Seal Coatings
Heat Seal Coverings are applied on film & foil substrates through different coating methods to achieve superior performance:
Extrusion Coating
In this continuous process, the sealant polymer is melted and extruded directly onto the substrate film moving through nip rolls. It offers uniform, economical coating of sealant up to several microns thick.
Lamination
Pre-made films of sealant polymers like LDPE are bonded to substrate films under heat and pressure to laminate them. This method works well for specialty substrates that cannot withstand extrusion temperatures.
Corona Treatment
The substrate surface is energized with corona discharge right before coating, which increases surface energy for better coating-substrate adhesion. Corona treatment enhances seal strength.
Printing Technologies
Flexographic, rotogravure, inkjet – Newer digital printing techniques are utilized to apply patterned or customized Heat Seal Coverings onto filmic substrates.
With appropriate coatings applied efficiently via the right methods, packaging manufacturers can unlock new package design possibilities. Converting operations also gain optimization in terms of output, reduced waste and enhanced shelf appeal.
Testing and Quality Control of Heat Seal Coverings
Comprehensive testing plays a key role in developing effective Heat Seal Coverings and ensuring consistent quality. Laboratory evaluation methods include:
– Seal Strength Testing – Peel and shear strength quantification at different temperatures, ambient and abusive conditions.
– Heat Seal Temperature Measurement – Differential scanning calorimetry to pinpoint seal initiation and melting properties.
– Microscopy – Visual examination under microscope to analyze coating morphology and seal interface.
– Aging Studies – Packages are stored at varying temperature/humidity levels and tested periodically for seal integrity over time.
– Extractable Testing – Chemical analysis of package/food contact to check compliance of seal layer components with regulations.
– Environmental Stress Testing – Simulated distribution simulations like stacking, shock, vibration etc. to evaluate durability.
Only Heat Seal Coverings that clear multiple rounds of stringent internal and third-party testing gain approval for use in high-volume packaging lines and applications with strict quality demands. Thorough QA/QC helps seal coat suppliers deliver consistent, safe products.
High-performance Heat Seal Coatings based on scientific formulation advance the packaging technology. Their diverse capabilities enable the manufacture of innovative, user-friendly and attractively designed packaging tailored to a wide range of market segments from food and beverage to consumer goods. With continued research on novel polymers, coating methods and testing techniques, heat seal technology will keep pushing packaging boundaries to deliver advanced protection and convenience. Heat Seal Coverings therefore remain a cornerstone of the thriving flexible packaging industry.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.
About Author - Money Singh
Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. LinkedIn Profile
