Natralock® CNK®

Natralock CNK

Designed to deter thefts while encouraging sustainability efforts.

Natralock® CNK® is specifically engineered as a clamshell replacement package to deter theft and enhance environmental sustainability objectives. It is designed for fold-over or two-piece trap seal blister card applications where added pilfer resistance is desired. And because it includes recycled fibers it can help brands meet sustainability goals. From a production standpoint, Natralock® CNK® allows heat and RF sealing compatible with a wide range of thermoform blister materials.

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Features & Benefits

What you can expect from us:

Laminated Structure

Combines the rigidity of paperboard with the tear-resistance of a proprietary lamination and extruded heat-sealing coating for unsurpassed assembly performance of trap seal blister packaging.

Heat Seal Compatibility

Consistently seals to a wide variety of thermoformed blister materials, including APET, RPET, PETG, RPETG, PVC and PLA.

Low-Temperature Seal

Seals at a lower temperature than competitive alternatives resulting in increased line speed. This also minimizes risk of product damage and ink degradation. Dwell time is up to 20% less than other heat-seal coatings, which results in improved throughput and decreases costs.

Product Uniformity

A smooth surface, outstanding ink holdout and best-in-class print consistency. Ideal for promotional messages, graphics and compliance information for trade seal blister packaging. Also, polymer coat-weight uniformity offers improved efficiencies and maximum throughput on high-speed filling equipment.

Converting Efficiency

Direct printing on the board eliminates the need to apply heat-seal coating. This improves converting efficiency and reduces inventory costs.


Roll-to-roll and sheet-to-sheet consistency makes Natralock CNK ideal for high-speed converting, filling and sealing applications.

Recycled Fiber Content

Produced with up to 15% recycled fiber, providing an option for meeting your corporate sustainability goals.


Best used with:

  • Health and Beauty
  • Media and Electronics
  • Sporting Goods
  • Toys
  • Automotive
  • Home Improvement
  • Tools

Paperboard Calculator

We understand that you rely on us for more than paperboard. In order to provide the best service possible, WestRock has developed roll, sheet and metric conversion calculators to make your job easier.

View the paperboard calculator

Additional Product Information


  • Made with recycled fiber.
  • All WestRock North American paperboard mills are certified to the SFI®, PEFC™, FSC™ Chain of Custody Standards. Contact your WestRock sales representative for certified fiber availability for this product.
  • Certificate Codes: SFI Certified Sourcing: NSF-SFI-CS-6S751, SFI CoC: NSF-SFICOC-6S751, PEFC: NSF-PEFCCOC-6S751, FSC Company Code: FSC-C104002.

Environmental & Product Safety

  • Notices under US California Proposition 65 and the EU REACH regulation and Safety are not required.
  • Meets heavy metal limits of the US Model Toxics in Packaging rules andArticle 11 of EU Directive 94/62/EC.

This information is subject to change without notice.


  • Produced at an ISO 9001 certified facility.

A clear choice for better security

To help boost security and remove barriers to purchase, we offer Natralock® tear-resistant packaging. As durable and secure as clamshells, Natralock provides superior product visibility and a safer, easier opening experience to help drive sales and profits.

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How can we help you meet your business goals? Contact a member of our team to learn more about our paperboard products and services.

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