The packaging bag looks better standing up!

People's purchasing power for fast-moving consumer goods continues to grow, and the rapid development of the FMCG market has also driven the rise of the flexible packaging industry. Nowadays, the types and uses of packaging bags are very widespread. At the same time, good packaging can also establish a high-quality image for products, enhance product competitiveness, and thus promote product sales.

1. Classification and advantages of stand-up pouches

Shunxingyuan Stand-up Pouch Family

There are many classifications of product packaging. If classified by technology, they can be divided into: moisture-proof packaging, waterproof packaging, mildew-proof packaging, fresh-keeping packaging, quick-freeze packaging, breathable packaging, microwave sterilization packaging, aseptic packaging, inflatable packaging, vacuum packaging, deoxidized packaging, blister packaging, skin packaging, stretch packaging, retort pouch packaging, etc. All the above-mentioned packaging bags are made of different composite materials, and their packaging characteristics correspond to the requirements of different products, effectively maintaining the quality and stable function of the product itself.

Stand-up pouches are considered a classic of modern packaging and a relatively new form of packaging. They offer certain advantages in terms of enhancing product grade, strengthening shelf visual effects, portability, convenience of use, water-proof, moisture-proof, oxidation-proof, and re-sealability. Stand-up pouches can be divided into five types: ordinary stand-up pouches, spouted stand-up pouches, zipper stand-up pouches, shaped spouted stand-up pouches, and custom-shaped stand-up pouches. They are mainly used in products such as fruit juice beverages, condiments, apparel, hardware electronics, washing products, and cosmetics.

Stand-up pouch packaging is very convenient for consumers because it is a plastic packaging bag, which is lightweight and not easily damaged. In addition, stand-up pouches with zippers can be reused, spouted stand-up pouches make it easier to pour out food, and exquisite printing can help products attract consumer attention.

Stand-up pouches are generally laminated with PET/FOIL/PET/PE structural layers, and can also have other specifications and materials such as 2-layer or 3-layer. Depending on the product being packaged, an oxygen barrier layer can be added as needed to reduce oxygen permeability and extend the product's shelf life.

Ordinary stand-up pouches and general forms of stand-up pouches adopt a four-sided sealed form and cannot be re-sealed or re-opened; spouted stand-up pouches are more convenient for pouring or sucking out contents, and can be re-sealed and re-opened, which can be considered a combination of a stand-up pouch and a common bottle mouth; imitation spouted stand-up pouches combine the convenience of spouted stand-up pouches with the low cost of ordinary stand-up pouches, meaning the function of a spout is achieved through the shape of the bag itself, but imitation spouted stand-up pouches cannot be re-sealed; custom-shaped stand-up pouches are new types of stand-up pouches with various shapes created by making changes to traditional bag shapes according to product needs, such as waist-cinching designs, bottom deformation designs, handle designs, etc.

2. Three common quality issues with stand-up pouches

1. Stand-up pouch leakage

The main reasons for stand-up pouch leakage lie in the selection of composite materials and heat seal strength.

1. Material selection

The choice of material for stand-up pouches is very important for preventing leakage. The purpose is to improve the peel strength between the outer layer and the intermediate barrier layer, and between the barrier layer and the heat seal layer materials, as well as the heat seal strength of the bag. Therefore, the film's surface tension on its composite side must be greater than 38 dyn/cm; the inner heat-sealable film must have good low-temperature heat-sealing performance, and the surface tension of the heat-sealable side must be less than 34 dyn/cm; in addition, inks with good bonding properties, high-solid-content, low-viscosity adhesives, and high-purity organic solvents should be used.

2. Heat seal strength

Low heat seal strength is also one of the important factors affecting stand-up pouch leakage. During heat sealing, the matching relationship between heat sealing temperature, heat sealing pressure, and heat sealing time must be adjusted properly. In particular, it is important to explore the heat sealing temperature for different bag structures, as different types of plastic films have different melting points and thus different heat sealing temperatures; the heat sealing pressure should not be too high, and the heat sealing time should not be too long, to prevent macromolecular degradation and the heat sealing layer from being sheared by the heat sealing knife in a high-temperature molten state, which would reduce the sealing strength. Furthermore, the four-layer sealing area at the bottom of the stand-up pouch is the most critical part, and the heat sealing temperature, heat sealing pressure, and heat sealing time should only be determined after thorough experimental verification.

In actual production, leakage tests should be performed on stand-up pouches according to the different requirements of the contents. The simplest and most practical method is to fill the bag with a certain amount of air, heat seal the opening, place it in a basin of water, and squeeze different parts of the bag with your hand. If no bubbles escape, it indicates good sealing integrity; otherwise, the heat sealing temperature and pressure of the leaking area should be adjusted promptly. Stand-up pouches containing liquid contents require even more careful handling; their leakage can be checked by squeezing and dropping methods. For example, fill the bag with a certain amount of water, seal it, and test according to the pressure test method in GB/T1005-1998. The drop test method can also refer to the above standard.

2. Uneven bag shape

Flatness is one of the indicators for evaluating the appearance quality of packaging bags. In addition to material factors, the flatness of stand-up pouches is also related to heat sealing temperature, heat sealing pressure, heat sealing time, and cooling effect. Too high a heat sealing temperature, too much heat sealing pressure, or too long a heat sealing time will cause shrinkage and deformation of the composite film. Insufficient cooling will result in insufficient setting after heat sealing, inability to eliminate internal stress, and cause wrinkles in the bag. Therefore, process parameters should be adjusted properly, and the cooling water circulation system should be ensured to work normally.

3. Poor symmetry

Asymmetry not only affects the appearance of the stand-up pouch but also its sealing performance. The most common asymmetry in stand-up pouches often manifests in the bottom material part. Improper tension control of the bottom material can cause deformation of the bottom hole or wrinkles due to a mismatch with the main material tension, leading to reduced heat seal strength. When the bottom material hole deforms, the unwinding tension should be appropriately reduced, and a waiting time should be increased during heat sealing for correction, so that the four-layer intersection at the bottom of the bag is sufficiently heat-sealed. In addition, asymmetric bag shape can also be related to factors such as photoelectric tracking, unwinding, mark design, rubber roller balance, and synchronization of stepping motors or servo motors. This problem needs to be resolved during specific operations based on different products and different bag-making equipment.

3. Two examples of stand-up pouch applications

1. Successful application of custom-shaped stand-up pouches

The zipper/bone strip also facilitates repeated opening and closing. However, the difference is that the repeated sealing method is a zipper/bone strip, so this type of design is not suitable for liquid packaging, but for packaging some dry goods, such as: clothing, hardware accessories, candy, dried fruit, chocolate, biscuits, jelly, tea, etc.

Shunxingyuan Packaging is a supplier of hardware packaging bags for famous sub-brands such as Masco's LIBERTY, BRAINERD, and HOME DECORATORS COLLECTION. Shunxingyuan Packaging can deeply explore customer needs and reasonably design specific solutions for product packaging upgrades, truly enabling enterprises to achieve more convenient and safe product usage, reduce costs, improve efficiency, enhance product aesthetics, and meet more environmentally friendly needs. Ultimately, when the supporting hardware packaging is delivered to the customer, the customer is also very satisfied.

2. Successful application of spout pouches

Nowadays, people's living standards are constantly improving, and more and more people are accustomed to using laundry detergent instead of laundry powder for washing. Because laundry detergent is convenient, quick, and does not require repeated cleaning, it saves time, effort, and water. Laundry detergent packaging mainly includes bagging and canning. Bagged laundry detergent packaging has higher requirements than ordinary soft packaging. The requirements for bag firmness, resistance to liquid corrosion and penetration, ability to withstand pressure from heavy objects, resistance to drops and scratches, transportation safety, and shelf display effects are more stringent.

Laundry detergent packaging bags are color-printed composite structures, the most common specification is 2 kg, and there are two common structures:

PET12/PA15/PE120

PET12/PA15/FOIL5/PE100

For the above composite structure film material selection, the specifications and performance of biaxially oriented polyester PET and biaxially oriented nylon PA are standardized. Polyethylene PE is the key to the quality of laundry detergent packaging bags. The laundry detergent packaging bags of a well-known brand use a Borstar bimodal polyethylene formula, which, compared with traditional polyethylene products, has the characteristics of high strength, burst resistance, impact resistance, good barrier properties, good rigidity and ability to stand upright, good stress cracking resistance, and good sealing.

Bagged laundry detergent mostly uses stand-up pouches. Adding a capped low-pressure polyethylene (HDPE) hard spout to the stand-up pouch forms a spout pouch. In addition to the advantages of bottle packaging, such as convenient opening and multiple sealing, it also has advantages such as less packaging material consumption, high printing and packaging level, low packaging storage and transportation costs, and small garbage disposal volume, and is known as environmentally friendly packaging. According to statistics, compared with the same capacity, the raw material consumption of bagged packaging is reduced by more than 30% compared with bottled packaging, the storage and transportation cost of packaging is reduced by more than 60%, and the amount of garbage disposal is also reduced by more than 5 times.