PET resin WK-631-The Perfect Solution for Flexible BOPET Packaging Films

1. What is BoPET

BoPET is a polyester film made from PET resin and was the first biaxially oriented polymer produced on a mass commercial scale. Known for its high transparency and durability, BoPET offers exceptional tensile strength, chemical stability, and dimensional stability. It also provides effective barriers against gases and moisture and serves as a superior electrical insulator.

BoPET film production involves extruding molten PET onto a chill roll, biaxially orienting it using heated rollers and ovens, and then heat setting and crystallizing it at temperatures above 200°C. Microscopic inert particles are added to prevent sticking, and the film can be metallized and laminated with polyethylene to enhance barrier properties and sealability for applications such as food packaging.

2. Applications of BoPET Films

In packaging and food contact, BoPET films offer superior barrier protection against oxygen, moisture, and light, significantly extending shelf life. They are used in advanced packaging solutions like metallized polybags and coffee foil packaging, and their excellent sealability and puncture resistance make them ideal for products such as Pop-Tarts and yogurt lids.

In industrial and technical fields, BoPET films are crucial for roasting bags, metallized films, and can manufacturing, replacing lacquers. They also enhance paper durability, serve as decorative surfaces, and provide archival protection for collectibles. Additionally, BoPET's insulating properties are utilized in spacesuits, emergency blankets, and various thermal and electrical applications. Emerging uses in aerospace, solar energy, and electronics highlight BoPET's broad adaptability.

3. BoPET Market Overview

The BoPET (Biaxially Oriented Polyethylene Terephthalate) market has seen substantial growth, driven by its diverse applications in packaging, electronics, optics, and industry. According to a report by Grand View Research, the global BoPET market was valued at approximately $9 billion in 2023 and is projected to grow at a compound annual growth rate (CAGR) of 6.8% through 2030.

The flexible packaging sector is a key driver, with PET's market share expected to grow at an annual rate of 6%-8%. However, the expanding share of PET films in new applications may impact its traditional dominance in the packaging sector.

According to Research and Markets, the Asia-Pacific region accounts for over 40% of the global BoPET market and is expected to continue its expansion. Overall, the BoPET market is poised for robust growth, supported by technological advancements and increasing demand for high-performance, eco-friendly materials.

4. WK-631: Optimal PET Resin for High-Quality BoPET Films

For high-quality BoPET films, PET resin should exhibit high crystallinity, good melt fluidity, and medium to low intrinsic viscosity for optimal stability and uniformity. It must also provide excellent optical clarity, gloss, and barrier properties to protect against oxygen, moisture, and light, ensuring both enhanced visual appeal and extended shelf life.

PET Chip Super Bright Type WK-631, developed by Wankai New Materials Co., Ltd, is a high-performance PET resin designed specifically for producing top-quality BoPET films. 

WK-631 exhibits the intrinsic viscosity(IV) of 0.64±0.02, which is lower compared to typical bottle-grade PET resins. PET resin with low IV facilitates easier stretching and molding during BoPET production, enhancing both production efficiency and film quality.

This PET resin provides an excellent color appearance, with a b-value of 0.55±2, ensuring high-quality aesthetics. Moreover, through advanced processing and stringent quality control by Wankai, WK-631 features extremely low impurity levels, further ensuring high film transparency and visual appeal.

The end-carboxyl group (-COOH）content of PET resin is a crucial factor influencing the performance of the final BoPET product. In terms of melt fluidity, PET resins with lower end-carboxyl content (such as 20-30 meq/kg) generally have higher molecular weight and less molecular chain interaction, which enhances melt fluidity. WK-631's end-carboxyl content of 26±4 contributes to its excellent flow properties, maintaining uniformity during BoPET films extrusion and stretching processes, thereby ensuring consistent films quality.

Additionally, an appropriate end-carboxyl content facilitates the crystallization rate and degree of crystallinity of PET. WK-631's end-carboxyl content endows it with excellent crystallinity, ensuring that BoPET films achieve optimal crystallinity during stretching and cooling, which enhances both mechanical and optical properties of the film.

WK-631 also demonstrates superior thermal stability with a melting peak temperature of 254±2, maintaining stability under high-temperature processing and usage conditions. This reduces issues related to fouling and degradation, thereby improving production efficiency and film consistency.

More importantly, Wankai's PET resin WK-631 boasts a IV value of 0.64±0.02, which offers significant advantages in international trade. Notably, WK-631 is minimally affected by export anti-dumping taxes, providing a competitive edge in global markets. This allows Wankai to maintain stable pricing and market presence, ensuring consistent access to international customers and enhancing trade opportunities. As a result, WK-631 stands out as a reliable and cost-effective choice for manufacturers worldwide.

5. Advantages of BoPET Over PE and PP in Flexible Packaging

In flexible packaging, BoPET excels over polyethylene (PE) and polypropylene (PP) due to its superior barrier properties, durability, and transparency. BoPET effectively blocks oxygen, moisture, and light, significantly extending shelf life for sensitive items like coffee and pharmaceuticals, whereas PE and PP have inferior barrier performance and are less suitable for long-term storage.

BoPET's mechanical strength surpasses that of PE and PP, offering greater resistance to tearing and impact. Additionally, BoPET provides high transparency and gloss, enhancing visual appeal and supporting high-quality printing. This contrasts with PE and PP, which require additional processing to achieve similar visual and printing quality.

BoPET also has a recycling rate of 30%-50%, benefiting from a well-established recycling infrastructure, compared to LDPE's 5%-10% and PP's 20%-30%, making it a more sustainable choice.

6. Conclusion

In summary, PET is a highly promising polymer, and its derivative, BoPET, is distinguished by its superior transparency, durability, and barrier properties. BoPET proves to be an invaluable material across flexible packaging and industrial applications due to its sustainability and effectiveness. With ongoing innovations, BoPET will continue to be essential for various industrial and commercial uses. Selecting the right PET resin for BoPET production requires careful consideration of its comprehensive performance attributes to ensure optimal results.