Window paper bags have become a favored choice for premium dried fruit packaging, especially for products like jujubes. This structure combines a natural paper exterior with a transparent window, creating a balance of authenticity, product visibility, and practical performance. The sturdy paper body gives the bag a clean and rustic appearance, while the built-in window allows consumers to see the color and quality of the jujubes inside, increasing both trust and purchase confidence.
Designed with multi layer materials, these bags provide solid protection from moisture, oxygen, and external contaminants, helping preserve the natural sweetness and texture of jujubes during transportation and storage. The reinforced bottom gives the bag a steady standing effect on shelves, and the wide opening makes filling and sealing smooth and efficient.
From a branding perspective, window paper bags offer a warm and natural canvas for design. The paper surface supports rich printing effects, making room for storytelling, origin details, nutritional information, and other brand elements. Together with the clear window, the result is a package that looks inviting and communicates product quality at first glance.
As a well-known flexible converter located in Qingdao, China, we are making the best use of the packaging film materials in the market, listed below.
- fossil chemical polymer films
- Aluminum foil metal sheet
- vacuum metalized film materials
- Ceramic film substrates
- plant-based biopolymer materials
- biodegradable film materials
- compostable substrate films
- Fully recyclable substrate films
In this post, we will introduce details about the exact film structure used in the 150 g Chinese dates paper bag. We hope this article can be helpful for people in need and facilitate their own packaging development.
MatteBOPP Film
Matte BOPP, also known as matte biaxially oriented polypropylene, is a polymer film with a soft matte surface that absorbs light rather than reflecting it. With its gentle matte appearance, this film is often used to enhance visual quality and bring a modern, elegant feel to packaging.
The structure consists of several layers, including a polypropylene core and tie layers. It is commonly co extruded with a skin copolymer layer on one or both sides. The film is produced through extrusion followed by biaxial stretching, and it can be manufactured through either the tubular process or the tenter frame process.
This combination of appearance, structure, and processing makes matte BOPP a popular choice for brands looking to achieve both refined aesthetics and dependable performance in their packaging.
KraftPaper Film
Brown kraft paper is a strong and durable paper made from wood pulp. It has a natural brown color with visible wood fibers, giving it an earthy and authentic appearance. The paper is known for its strength and resistance to tearing, which makes it suitable for many types of applications.
Common uses of brown kraft paper：
- Packaging：Brown kraft paper is often used for shipping, wrapping, and protective packaging. It appears in corrugated boxes, carton structures, and fluting. It can also be used in grease resistant formats, since it can temporarily prevent the penetration of oils and fats.
- Arts and crafts：Because of its natural look and workable texture, kraft paper is popular for crafts, bookbinding, and creative projects.
- Additional applications：Kraft paper is also used for printing, gift wrapping, clothing tags, surface protection, and many everyday uses.
Kraft paper is considered environmentally friendly because it is made from renewable wood pulp and usually does not undergo heavy bleaching. It can be recycled and used again in packaging applications. When kraft paper is coated with polyethylene for moisture and grease resistance, its recyclability becomes more limited. Zein coated kraft paper is an alternative that offers moisture protection while maintaining better recyclability.
VMPET Film
VMPET film is the short form of vacuum metallized polyester film. It is produced by depositing a very thin layer of aluminum onto the surface of a PET film in a controlled vacuum environment. This process creates a bright metallic appearance and gives the material strong functional performance, making VMPET widely used in flexible packaging and standup pouches.
Vacuum metallizing serves both decorative and functional purposes:
- Decorative：The technique enhances the appearance of the material with metallic colors such as copper, brass, titanium, or stainless steel. It also gives packaging a distinctive visual effect with either a bright or matte metallic finish.
- Functional：Vacuum metallizing can create reflective and shielding layers. Aluminum based reflective coatings can reach very high reflectivity, while shielding coatings made from conductive metals such as aluminum or copper can help block electronic interference. The process can also improve vapor barrier properties and provide heat shielding.
VMPET film, through this process, combines aesthetic value with reliable protection, making it an important material in modern packaging applications.
LDPE Film
LDPE, or low-density polyethylene, is a thermoplastic polymer that is a member of the polyethylene family of plastics. It is known for its flexibility, toughness, transparency, and corrosion resistance. LDPE is also lightweight, easy to fabricate, and has good chemical and impact resistance. It is often used for manufacturing plastic goods like cling wrap, juice containers, orthotics, and prosthetics.
LDPE is recyclable and reusable, which makes it a popular option for reducing dependence on traditional plastics. However, the FDA does not consider recycled LDPE suitable for direct contact with food. Products made from LDPE are usually marked with the number four inside a triangle, most often found on the bottom or side of the item.
These 4 layers are bonded together into a finished laminated foil material under the dry lamination or solvent-free lamination process. Usually, we describe the finished laminate as MatteBOPP/KraftPaper/MPET/LDPE foil.
Great Standup Effect
This multi layer structure combines matte BOPP, kraft paper, metallized PET, and LDPE. The combination creates a pouch with excellent strength, refined visual texture, and reliable protection for a wide range of products. The kraft paper layer offers a natural and premium look, while the matte BOPP surface adds a soft and modern appearance. The metallized PET layer enhances barrier properties and improves light protection, and the LDPE layer provides solid sealing performance and flexibility.
This structure allows the pouch to stand upright even before filling and maintain stable standing after filling. The layers work together to improve shelf stability and reduce the chance of tipping. Kraft paper increases rigidity, metallized PET strengthens barrier performance, and LDPE supports dependable sealing. The full structure achieves both an attractive appearance and strong functional performance.
Advantages of the Transparent Window:
- Enhanced Shelf Appeal:A transparent window placed on the side panel introduces a clean and warm balance between natural kraft texture and product visibility. Customers can see the product clearly while the front panel remains neat and uninterrupted.
- Better Use of Branding Space:Since the window is positioned on the side, the entire front and back surfaces remain open for creative artwork, storytelling, ingredient details, or sustainability information. This helps brands achieve strong shelf presence while still providing a direct view of the product inside.
Excellent Airtight Property for Zipper lock
It forms a firm bond with the inner LDPE layer of the pouch, creating strong airtight protection. This makes it easy for customers to open and close the package many times while keeping the contents fresh for a long period after the first opening.
We follow a strict quality control process to confirm the zipper’s airtight performance. If you would like a clearer view of how the test is carried out, you can check the demonstration video below.
Mechanical Property
This reinforced laminated foil is achieved with great mechanical strength, with some standard items as below.
- Tensile Strength
- Sealing Strength
- Anti-puncture Strength
- Burst Impact Strength
- Anti-pressure Property
The above tests are performed against each order based on customer requirements.
Drop Test
During our daily quality control process, we use a dependable method to assess whether the strength of each bag meets the final expectations of different customers. Every order includes a drop test, and the testing standard is adjusted based on the customer’s specific requirements and the performance level they expect.
In this case, the drop test is carried out from a height of one point six meters. The bag is dropped three times, and we then check carefully to confirm that it has not broken.
Barrier Performance
Usually, the barrier performance of a multi-material laminate is evaluated by WVTR (short for water vapor transmission rate) and OTR (Oxygen Transmission Rate). The below table shows the typical value of the WVTR and OTR of the most common substrate films in flexible packaging.
Based on our experience, MatteBOPP/KraftPaper/MPET/LDPE foil laminate will be able to meet most of the requirements for platinum chips. WVTR (short for water vapor transmission rate) and OTR (Oxygen Transmission Rate) are evaluated for this laminated foil, with typical values listed in the below table.
| Item | Standard | Unit | Typical Value |
| Water Vapor Transimission Rate | ASTM E 96 | g/m2/24hr | 1.25 |
| Oxygen Transmission Rate | ASTM D 372-99 | cc/m2/24hr | 1.36 |
More Sustainable Materials Options
With the increasing environmental burden caused by fossil-based polymer waste, the demand for sustainable packaging continues to rise. Recent studies in the detergent market indicate that consumers are becoming more willing to purchase products that clearly demonstrate a commitment to environmental responsibility.
Compostable Packaging Materials
This kraft paper PLA+PBAT film pouch was burid into soil on Nov 26, 2021, and one and half years passed, dated on August 17, 2023, we are going to check the degradation process of this compostable foil pouch. Actually, all the outside layer kraft paper degraded into inorganic elements without any things left. However, the inner PLA+PBAT film did not degrade into nutrients. Surely, the activity of micro-organism is keeping a lower level for soil conditions and surely it will need a longer time to degrade. We got it well buried again, and surely, we will keep you posted with the progress of this composting test.
We have developed several compostable foil materials that can be intended for roasted sunflower seeds, with the list below.
- Cellulose/Metallized Cellulose/PLA+PBAT Film
- Metallized Paper/Cellulose/VMPET/PLA+PBAT Film
- Kraft Paper/Metallized Cellulose/PLA+PBAT Film
Fully Recyclable Mono Materials
Compared with the higher cost of compostable foil materials, fully recyclable sachets and roll films are quickly becoming the preferred choice in the market due to their cost-effectiveness and suitability for lightweight packaging.
Thanks to ongoing advancements in PE film barrier technology, recyclable foil-free laminates can now provide reliable protection for products such as sunflower seeds by effectively blocking moisture. For applications requiring even stronger performance, a PVA coating can be applied to LDPE or HDPE films to further improve moisture resistance. In addition, integrating an EVOH barrier layer into biaxially oriented PE (BOPE) films significantly enhances oxygen barrier properties, making this structure an excellent solution for modern flexible packaging.
If you have any questions or would like to learn more about our juice pouch packaging solutions, please feel free to reach out.
Have a great day!