Cold-Seal Packaging
Cold-Seal Packaging is a packaging method for a range of products. Cold-seal technology uses a special adhesive that makes it possible to package and ship heat-sensitive products. When compared to conventional heat-sealable films, which require heat to seal a packaging component, cold-seal technology reduces energy costs and improves co-packing speeds since heat is absent. Spoilage and setup on the packing line are also reduced with cold-seal packaging.
A cold-seal package can consist of a single structure or two separate films. The first film is reverse-printed with the company name, logo, and graphics. The second film is a barrier that protects the package’s contents. A laminate is then used to secure the two films in a conjoined web. Next, a cold seal adhesive is applied to the web’s inner surface in a pattern that aligns with and preserves the exterior graphics.
The cold-seal which makes this packaging solution possible is an adhesive that is engineered to stick to itself with low pressure. This makes it possible to protect sensitive materials inside the package. Cold-seal adhesives are naturally-based materials. If handled incorrectly, they are a relatively unstable substance.
While cold-seal technology brings many possibilities to the market regarding the manufacture and shipping of sensitive materials, such as food and medical products. Specialized knowledge is required to properly apply cold-seal technology to packaging.
Cold-Seal Adhesives[edit]
Cold-seal adhesives are commonly used to seal and protect heat-sensitive products. Often referred to as self-seal adhesives, the adhesive substance is applied to the packaging material in a way that allows the packaging to seal without using heat. The packaging is bonded together with pressure where the cold-seal adhesive only sticks to itself, unlike pressure-sensitive adhesives.
Packaging that uses cold-seal technology does not need a release liner. In its place, a release coating is either applied after printing, or is part of the inherent packaging structure. The adhesive won’t stick to itself, and will flow and release freely while running on an automated packaging line. As a result, cold-seal adhesive reduces material usage often required in paper packaging, but without risking damage to the packaging contents.
Cold-seal adhesives are composed of mixtures of natural latex rubber, and adhesive substances. Since natural latex rubber is a known allergen[1], medical packaging must be labeled appropriately. In 1999, the Food and Drug Administration (FDA)[2] required medical packaging that uses cold-seal technology and natural rubber latex to include the appropriate labels.
Base polymers used in cold-seal adhesives must bond to themselves with little pressure, while being durable enough to withstand adhering to another substrate when the packaging is assembled and stored. Natural latex rubber, butyl, polyisoprene, and some silicone rubber formulations are polymers that offer the ideal autohesion necessary for cold-seal technology.
Synthetic cold-seal technology also exists to avoid the use of potential allergens like natural rubber latex. The same bonding benefits present in cold-seal adhesives with natural rubber latex is also present in synthetic cold-seal adhesives. Layered substrates are also reeled into rolls and stored. These rolls are ideal for forming packages used to protect and ship medications and food.
Cold-Seal Technology and Pharmaceuticals[edit]
Cold-seal technology (also called self-seal or cohesive seals) has an important role in creating sterile and non-sterile packaging in the pharmaceutical industry. Specialized packaging using self-seal adhesives is often required for bandages, pharmaceutical drugs, overwraps, and other medical devices. Cold-seal solutions form a strong adhesive bond suitable for the rigors of the medical profession. Therefore, this type of packaging is ideal to meet the exacting standards required in the pharmaceutical industry.
Blister packaging is one way cold-seal adhesives can be used effectively in pharmaceuticals. Cold-seal bonds have excellent adhesion to foil, making them an ideal sealant for various drugs and medical supplies. Packaging using cold form blister packaging includes capsules, tablets, pills, syringes, and ampoules. Using cold-seal foils, manufacturers can create cost-effective peelable, push-through, tear-open, peel-push, and child-resistant seals.
Synthetic latex in cold-seal pharmaceutical packaging means that all hospitals and medical facilities can safely use a wide range of medical products. Many hospitals in the United States have banned the use of any products containing latex.
History[edit]
Cold-seal adhesive was developed in 1984 by adhesive manufacturing company Bostik. Until then, heat-seal technology was the standard for sealing plastic packaging. The disadvantages of heat-seal technology made it impractical for mass production of certain products. Using a combination of rubber, resins, and other additives, an adhesive bond was formed that only required pressure to seal it — without using heat.
Advancements in technology have made it possible to use a wide range of products, suitable for many uses. For example, combining ethylene and vinyl acetate with rubber latex created an adhesive formulation of varying strengths.
The use of synthetic rubber was another step forward in creating a new type of latex-free cold-seal adhesives. In 1998, the company 3M filed a patent for a “substantially natural latex rubber-free contact adhesive.” This was a breakthrough in creating cold-seal packages suitable for the pharmaceutical industry. The advantages of this technology are that it is suitable for people with latex allergies, it does not discolor with age, and it does not have an unpleasant rubbery odor.
Although cold-seal adhesive technology was described as a “disruptive technology” when it was first introduced, it is now the standard for packaging many types of products.
Limits of Heat-Seal Technology[edit]
Cold-seal adhesive revolutionized the packaging industry because it addressed many of the limitations of heat seal packaging. The disadvantages of heat seal adhesives are that they require heat to seal the packaging. While this can be an effective way of applying and fixing adhesive, its use is limited. High temperatures are not suitable for packaging chocolate, flammable liquids, or other volatile substances. Additionally, heat seal adhesives are not effective on corrugated packaging.
Other limitations of heat-seal adhesives are the length of time and the pressure required to fix the adhesives. Heat, pressure, and dwell time must be in precise balance for the bond to be effective. This sealing process limits the use of heat seal technology on many packaging lines. The result is often packaging that does not meet a manufacturer’s standards or slow processing in the packaging line.
The main disadvantage of heat-sealing technology is speed. Compared to heat seal adhesives, the cold seal process is quicker, with processing speeds of up to 10 times faster than heat sealing. The slower processing speed involved in heat sealing occurs because heat must be generated at startup, and equipment needs to cool down. It is not until the product is cold does the adhesive solidify, forming a strong bond between the two packaging layers. There is also a risk of burn injuries using heal sealing equipment.
Limitations in Cold-Seal Technology[edit]
The primary limitation of cold-seal adhesives is that there is no chemical resistance that may be necessary for certain products depending on FDA requirements. Additionally, cold seal applications are sensitive to air contact and require a suitable release surface.
Some types of products are not suitable for using cold seal adhesive coatings. While cold seal is better for candy bars and medical packaging, heat seal is better for sealing bottle caps and yogurt tubs.
Compared to heat sealing, cold sealing results in a weaker bond strength, which may not be suitable for all types of products.
Uses and Economic Importance[edit]
Cold-seal adhesives have a broad range of use in the packaging industry. No heat is used in cold-seal packaging, meaning that manufacturers can use the technology to package granola bars, chocolate bars, or protein bars. Packaging medical products like blister cards, pharmaceutical wallets, adhesive bandages, and other products is possible with cold seal.
Cold-seal technology is alow-cost method: it only requires pressure results in a simpler and faster process. No heat is involved, which makes cold sealing more environmentally friendly. Energy costs are also reduced when companies switch from heat sealing to cold-seal technology. Faster line speeds, lower energy bills, and simplified maintenance mean that production can be more cost-effective. It is possible to either make savings or increase production. There is also less waste and product damage. There is no risk of damaging heat-sensitive products due to heat or thermal burning.
Companies using cold-seal production lines also limit their exposure to workplace injuries. Studies show that over 40% of all work-related injuries are related to thermal burns. By eliminating heat-producing equipment, companies create a safer workplace environment for employees. Additionally, people working on cold-seal packaging lines are exposed to less noise, smell, and fewer hazardous conditions.
Cold sealing equipment can handle a wide range of eco-friendly materials. Cold seal solutions can use recycled cardboard and recycled plastic. It is also possible to produce recyclable products because of a 100% separation of board from plastic.
Typically, it is easy to make the transition from heat seal to cold seal. Existing heat-sealing equipment can often run a cold seal flow wrap by switching off the heat. In other cases, companies may need to purchase a cold-seal jaw to install on existing production lines.
References[edit]
- ↑ "Latex Allergies | NIOSH | CDC". www.cdc.gov. 2020-02-24. Retrieved 2021-03-27.
- ↑ "CFR - Code of Federal Regulations Title 21". www.accessdata.fda.gov. Retrieved 2021-03-27.
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