Description

What is an OPP self-adhesive bag?

OPP self-adhesive bags are transparent, sturdy plastic packaging bags made from oriented polypropylene. Their standout feature is the self-adhesive strip at the opening; simply peel off the protective film to seal the bag quickly and easily, without any tools.

They have advantages such as resistance to dust and moisture, excellent display quality, and are often called “self-adhesive OPP bags” or “transparent OPP bags”, and are widely used for packaging clothing, stationery, food, postcards, and other products.

Key features and main applications of self-adhesive OPP bags:

Material and structure: OPP material is crisp and rigid with extremely high transparency, enhancing the product’s visual presentation.
Easy sealing: The self-adhesive design (usually including a flap) allows sealing in one second, saving packaging labor costs.

Usage examples:

E-commerce packaging: Clothing, stationery, cosmetics.
Food packaging: Cookies, baked goods (requiring food-grade OPP film).
Display packaging: Books, greeting cards, cultural and creative products, electronic components.
Specifications: The size, thickness, and length of the self-adhesive sealing flap can be customized (e.g.: +4cm is the length of the sealing fold).

Self-adhesive OPP bags are a standard packaging solution for fast-moving consumer goods. Transparent and clear, they are a professional choice for enhancing the aesthetic appeal of your products.

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OPP bag printing production process

The OPP bag printing production process mainly includes steps such as raw material extrusion, biaxial stretching (film formation), printing, and bag making (cutting, sealing, and tape application). First, PP raw material is extruded into a thick sheet, then stretched longitudinally and transversely to improve transparency and stiffness. After that, patterns can be printed, and finally, an automatic bag-making machine completes the production of three-side-sealed bags or self-adhesive bags.

Core production process:

Raw material extrusion: Polypropylene (PP) pellets are heated and melted, then extruded through a die to form a thick film sheet.
Biaxial stretching: Through longitudinal and transverse stretching, the molecules are arranged in an orderly manner.
This step is crucial for OPP’s high transparency, high stiffness, and tensile strength.
Printing: Color or pattern printing is carried out on the biaxially stretched film.

Bag production process:

Cutting and edge sealing: The film is cut to the required size using a bag-making machine, and both edges are sealed using a heat-sealing process.
Self-adhesive/Non-adhesive bags: Depending on requirements, open bags, flat bags, or bags with a pre-applied self-adhesive strip at the bag opening can be produced.

Common types of bags:

Self-adhesive OPP bags: Equipped with a pre-applied adhesive strip at the bag opening; simply peel and seal, easy to use.
Flat OPP bags: Standard opening, with no adhesive.
Hanging OPP bags: Equipped with convenient hanging holes for displaying products in supermarkets.

Common Issues When Producing Printed OPP Bags with Adhesive Seals

The production of printed OPP bags (biaxially oriented polypropylene film bags) is a precise process in industrial manufacturing. Common issues mainly fall into four aspects: printing quality, film handling, bag-making processes, and surface treatment:

1. Printing and Ink Issues

Faded Printing/Poor Adhesion: OPP has low surface tension. If it has not been treated with corona treatment (surface treatment), the ink will not adhere firmly, causing the printed image to peel off easily.
Ink Blocking/Adhesion: Printing over large areas or winding the film before the ink has completely dried can cause the printed surface to stick to the back of the bag, resulting in tearing or stains.
Misregistration (Ghosting): During multi-color printing, improper control of film tension or mechanical faults can cause color misregistration.
Blurred Printing/Uneven Printing Pressure: Insufficient printing pressure or ink drying too quickly can result in unclear printed images.

2. Film and Surface Treatment Issues

Insufficient Corona Treatment: If the OPP film surface does not meet the required surface tension standard (typically >38 dynes), it will directly cause the printed ink layer to peel off.
Static Electricity Issues: OPP is an insulator and is prone to static electricity during production, leading to dust attraction, uneven winding, or dust adhering to the film surface during bag making.
Foreign Matter/Scratches on the Film Surface: Unclean guide rollers or mechanical friction can cause scratches on the film surface, affecting its appearance.

3. Issues with bag making and sealing

Weak or brittle seals: Excessively high sealing temperatures lead to brittleness, while insufficient temperature or time results in weak seal adhesion.
Wrinkles at the sealing point: Improper adjustment of material tension leads to uneven film at the cutting machine.
Uneven cutting/Size errors: Worn cutting blades or an unstable tension control system result in inconsistent bag lengths or uneven edges.

4. Environmental and post-printing handling issues

Residual ink odor: Using solvents with low boiling points or setting the drying oven temperature too low leads to incomplete evaporation of ink solvents, affecting the packaged goods (especially food).
Self-adhesive bag glue does not adhere: Poor quality or moisture in the sealing strip causes the self-adhesive function to fail.

Solutions:

Enhance corona treatment: Ensure the surface tension meets the required standard before printing.
Strictly control tension and temperature: Adjust the heat-sealing temperature and web tension according to the film characteristics and printing speed.
Ensure the ink is completely dry: Ensure the ink is completely dry after printing before making bags or winding the bags.
Maintain a clean environment: Clean the guide rollers to reduce static electricity.

Characteristics of OPP bags:

Non-toxic, odorless, non-toxic, with a dull appearance, in the form of milky white waxy granules with a density of 0.920g/cm3, and a melting point of 130°C 145°C. Insoluble in water and slightly soluble in hydrocarbons, toluene, and other chemicals. It has low water absorption and can retain its softness and high electrical insulation properties even at low temperatures.

Five benefits of OPP bags:

Anti-fog: Anti-fog material reduces visual obstructions, allowing you to clearly see the freshness and beauty of fruits and vegetables. This will help increase product sales.
Food grade: Food-grade material that can come into direct contact with food. Grade A: Good flatness and gloss.
Breathable design: Ventilation holes on both sides allow fruits and vegetables to breathe freely. This extends freshness.
Custom color logo: Our professional design team will assist you in customizing the storefront and highlighting its features.
Explosion-proof edge sealing process: The side seals are made using a heat-sealing process. The 5mm self-adhesive glue is durable and secure.

The Opp bag packaging has high transparency and crispness. One piece of OPP is folded in half and the sides are sealed. The opening flap is sealed with self-adhesive glue. To protect the product, peel it off and fold the flap. It is flexible, beautiful, and widely used in food, clothing, stationery printing, cosmetics, paper, and other industries. Opp bag packaging Customers can request customized sizes and processes.

Applications of OPP bags in daily life

In daily life: used to wrap books, notebooks, package clothing, and stationery.
In food packaging: a top choice for packaging pastries, candy, and fast food.
In healthcare: used to preserve medical equipment, face masks, and herbal products.
In the garment industry: used to preserve and package clothing, bedding, bed sheets, and mattresses.
In organizations: used to package documents, records, or stationery.
In advertising: used as product display packaging and printed packaging to promote brands for businesses and stores.

Why should you choose OPP plastic bags?

Aesthetic appearance and transparency: One of the biggest advantages of OPP bags is their superior transparency. This allows the product to be clearly seen from all sides, providing an attractive and professional appearance. Whether it is confectionery such as cookies or candy, or food products such as nuts or cereals, these bags help highlight their natural beauty.
High quality and durability: Made from high-quality OPP plastic, these bags are sturdy and resistant to mechanical damage. They can withstand various loads and are suitable for packaging both small and large products. In addition, the securely sealed bottom provides extra stability and protection, ensuring that even bulk products are packaged safely.
Hygiene and safety: These bags are completely safe for use with food. They meet all food safety standards, making them perfect for direct contact with food. This is especially important for confectionery products, which need to retain their freshness and quality.
Economical solution: OPP plastic bags are sold in packs of 100, which is very convenient for both retail and wholesale orders. This is a cost-effective solution that allows you to optimize the packaging process and reduce costs.

Can OPP bags be recycled?

OPP plastic film can be recycled just like other types of PP film. Although it is a very common single-use plastic worldwide, it may be one of the least recycled types. OPP plastic film manufacturers often mistakenly consider OPP film waste to be simply general waste. However, this plastic material in various forms, such as OPP tape, labels, and OPP wrapping film, can be recycled.

How to Store OPP Plastic Bags

The important thing when storing OPP bags (polypropylene film bags) is “a dry, well-ventilated, cool place, away from light and pressure”. The bags should be placed in a well-ventilated, cool area, away from direct sunlight and high temperatures (to prevent shrinkage and deformation). They should be laid flat or neatly stacked to prevent wrinkling and kept dry. At the same time, they should be kept out of the reach of children to avoid the risk of suffocation.

Specific storage suggestions are as follows:

Choose the environment: Store in a dry, cool, well-ventilated place and avoid direct sunlight. Do not place the bags under direct sunlight or in places with high temperatures (such as inside a car), because OPP is a plastic material, and high temperatures can easily cause deformation, shrinkage or peeling of the self-adhesive layer.

Avoid exposure to light: Prolonged direct exposure to sunlight will cause OPP material to yellow and become brittle.
Store properly: Stack the bags flat to avoid prolonged compression by heavy objects, which can cause irreversible wrinkles.
Prevent mold and contamination: Use specialized bags or plastic boxes for storage, keep the packaging clean and prevent dust from entering inside.
Check regularly: If they are self-adhesive bags, check whether the self-adhesive layer has peeled off after a long period of storage.

Why store them this way?

OPP plastic bags (Oriented Polypropylene) are characterized by high transparency and good rigidity, but this material is sensitive to light and heat. It can easily melt and deform when the environment is too hot, and prolonged exposure to light will accelerate the aging process.

Why should you trust Hadupack for your packaging needs?

If you are looking for a packaging manufacturing and supply partner with extensive experience in providing quality products and services, d.a.pak is ready to support you. Here are our highlights:

Integrity is key: We are committed to always doing the right thing. This means paying fair wages, protecting rights, and never compromising our principles for profit.
We always strive for excellence: Whether it is developing more sustainable packaging or innovating to meet new challenges, we always strive to exceed expectations.
We are committed to sustainability: Creating a sustainable world requires continuous effort and dedication. We value our environmental responsibility and actively work to minimize our impact through sustainable practices.

Easy purchasing and fast delivery. You can purchase all types of BOPP plastic bags we offer at our online store or visit our physical store. We ensure fast and convenient delivery for customers shopping online – bags are delivered within 1-3 business days in Hanoi. This allows you to plan your activities without interruption and ensures a smooth workflow.

Why should you choose our bags?

By choosing our transparent OPP plastic bags, you will get a high-quality, practical, and attractive product. We understand that every customer’s needs are different, so we aim to provide personalized solutions that meet your business or personal expectations.

Let your products shine through high-quality, transparent OPP bags – this is a simple yet effective way to highlight their uniqueness and quality !