Elevate Your Bottle Quality: How PET WK-811 and WK-811L Optimize Hot-Fill Applications

The core principle of hot filling technology involves using high temperatures to instantaneously kill microorganisms in the liquid, thereby extending the product's shelf life. During the filling process, the liquid is heated to a temperature between 85°C and 95°C and then rapidly filled into pre-sterilized containers. The high-temperature filling creates a certain degree of vacuum inside the bottle, effectively preventing microbial growth and enhancing product safety.

Most soft drinks are packaged in PET bottles; however, due to the specific requirements of the hot filling process, the PET resin used for this application differs significantly from standard water bottle-grade PET. Hot-fill PET must exhibit exceptional heat resistance, stability, and good processing performance to meet stricter production standards.

Special Requirements for PET in Hot Filling

In the hot filling process, PET materials must withstand the impact of high-temperature liquids, necessitating elevated performance standards. Typically, the melting point of hot-fill PET needs to reach approximately 240°C to maintain its shape and physical properties during high-temperature filling without deformation or softening. Additionally, hot-fill PET should have high oxygen and water vapor barrier properties. As the temperature of the liquid inside the bottle gradually decreases post-filling, the PET material must maintain a low oxygen permeability to prevent oxygen infiltration, which could compromise the flavor and quality of the food product. Furthermore, low water vapor permeability effectively prevents moisture loss in high-temperature environments, preserving the freshness and taste of the beverage.

Beyond excellent barrier properties, hot-fill PET must also possess good mechanical strength to withstand the pressure and impacts encountered during the filling process. Its impact resistance and tensile strength must be sufficiently high to ensure the bottle maintains structural integrity throughout production and filling. Moreover, as PET can become hazy at high temperatures, hot-fill PET must have good crystallization properties to ensure exceptional clarity and surface finish, meeting high standards for visual appeal and packaging quality. Importantly, materials must not release any harmful substances under high-temperature filling conditions to comply with strict food safety and hygiene standards.

Wankai Brand Hot-Fill Grade PET: WK-811 and WK-811L

Wankai New Materials Co., Ltd. is a leading enterprise focused on the research, development, production, and sales of high-performance PET materials. Committed to providing quality, efficient, and sustainable material solutions to global customers, Wankai has established itself as a preferred partner in the food, beverage, and other packaging industries through years of experience and ongoing technological innovation.

Wankai’s diverse product range includes standard bottle-grade PET, hot-fill bottle-grade PET, oil bottle-grade PET, carbonated soft drinks bottle-grade PET, and specialty functional PET resins. All products strictly adhere to international standards, ensuring stable quality, superior performance, and broad market applicability.

Among these, WK-811 and WK-811L are two high-performance PET resins specifically developed for hot-filling applications, designed to meet the performance requirements of bottle integrity under high-temperature conditions. Unlike traditional bottle-grade PET, these hot-fill grades offer outstanding heat resistance, stability, and excellent processing performance, making them ideal for packaging tea beverages, juices, condiments, and other products that require high-temperature filling for sterilization.

Superior Properties of WK-811 and WK-811L

1.Outstanding Heat Resistance

WK-811 and WK-811L have a melting peak temperature of 251±2°C, significantly higher than that of standard water bottle-grade PET, enabling them to meet the hot-filling process requirements below 90°C. Under high-temperature conditions, the bottles maintain stable shapes without deformation, softening, or shrinkage, ensuring the packaging's appearance and usability.

2.Excellent Barrier Properties

In hot-filled soft drinks, controlling internal oxygen and moisture levels becomes critical as the temperature decreases post-filling. WK-811 and WK-811L exhibit high oxygen and water vapor barrier properties, effectively preventing oxygen infiltration that can degrade the beverage's flavor while maintaining stable moisture levels to prolong shelf life and ensure the beverage's taste and quality.

3.High Mechanical Strength and Attractive Appearance

Both PET resins maintain excellent mechanical performance in high-temperature environments, including impact resistance and tensile strength, ensuring the bottle's integrity during filling, transportation, and storage, while preventing breakage, bursting, or deformation. Additionally, superior crystallization properties enhance the bottle's clarity and finish, meeting market demands for high-end packaging aesthetics.

4.Excellent Processing Performance and Equipment Compatibility

The molecular weight and distribution of WK-811 and WK-811L are finely tuned to ensure high orientation rates and stable crystallization during bottle production. The uniform wall thickness distribution and low residual stress allow compatibility with various mainstream bottling equipment, improving production efficiency and reducing yield fluctuations, significantly enhancing the operational stability of customers’ production lines.

5.Compliance with International Food Safety Standards

Wankai maintains stringent quality control, employing advanced impurity removal technologies during production. As a result, WK-811 and WK-811L have heavy metal and acetaldehyde content well below international standards, complying with EU and FDA regulations for food contact safety, offering customers safer and more environmentally friendly packaging material options.

Broad Application Spectrum of WK-811 and WK-811L

WK-811 and WK-811L are primarily used for liquid packaging under high-temperature conditions, including but not limited to:

Tea and Juice Bottles: Particularly suitable for green tea, oolong tea, and mixed fruit juices that require high-temperature filling around 90°C.

Condiment Packaging: Widely used for packaging soy sauce, vinegar, and other condiments, ensuring bottle performance stability during high-temperature filling.

Other Hot-Filled Food Packaging: Applicable for soups, liquid sauces, and other food products requiring high-temperature processing, ensuring effective protection of flavor and safety.

Conclusion

Wankai has effectively addressed the challenges of hot filling technology with its innovative WK-811 and WK-811L PET resins. With ongoing technological innovation, Wankai maintains a leading position in the PET resin market, providing efficient, sustainable, and safe packaging solutions for its customers.