Michelman Repulpable Water-Based Coatings for Paper, Paint and Coating Applications

Michelman products enhance the surface qualities of coatings and inks, make composites tougher, and expand the possibilities of paper and film with barrier, functional, and aesthetic features. Michelman's extraordinary technical support helps ensure those products deliver all they can to your bottom line.

Michelman can help you build next-generation performance into your products today. If you’re looking for a product using established surface modifier or coating technology, chances are we have it in stock. If you want something new, Michelman like to discuss your needs. Many customer collaborations have resulted in product breakthroughs that still lead their markets today.

Paper Packaging with Repulpable Water-Based Coatings

Since pioneering repulpable water-based coatings for corrugated paper packaging in 1963, thousands of packaging converters have used, recycled, and repulped hundreds of Michelman coating formulations. In the past Michelman demonstrated repulpability by using the TAPPI Method T205 (British disintegrator).

Benefits of Repulpable Coatings - Environmental and Economical

There are many environmental and financial benefits to using repulpable coatings on paper and corrugated. The water-based chemistry Michelman uses for its coatings is environmentally friendly, and the OCC (Old Corrugated Containers) can then be sold to recyclers for profit. This saves box users the expense of paying to send their OCC to landfills.

Michelman is testing and validating the repulpability of its coatings when applied to liner board, using a voluntary yet more stringent protocol established by a joint committee of the Fibre Box Association and the American Forest & Paper Association. (see sidebar) This joint committee represents manufacturers of container board, corrugated containers and others who use recovered corrugated container fiber.

Applications of Michelman Repulpable Coatings

A few of the coatings that Michelman has successfully tested for repulpability, and their applications include:

  • VaporCoat® 330C - a wax replacement solution typically used on roll wrap, produce boxes, poultry boxes and anywhere packaged goods require protection from water and/or moisture vapor.
  • Michem® Coat 40EAF - another wax replacement coating that is water resistant and also demonstrates some grease resistance. Typically used on fruit, vegetable and protein/meat boxes.
  • Nomar™ 70AF - a water based, abrasion resistant coating, generally used to provide abrasion protection for gas flushed food packaging or small appliances.
  • Coating X300AF™ - another waterborne coating that provides a high level of water resistance and good moisture resistance on kraft paper. It is used to protect food products from excessive moisture, freezer burn and sticking.
  • MaxWhite™ 17 - a decorative white coating that provides excellent brightness before and after wax applications.

Michem Surface Modifiers for the Paint and Coating Applications

Likewise, in the paint and coatings industries, Michelman technology helps manufacturers eliminate solvents and reduce VOCs. Michelman works with nearly every type of wax and wax-like polymer in use today, and formulators have used Michem® surface modifiers to meet a wide variety of objectives in paint and coating formulations including:

  • Stopping water penetration into wood and concrete
  • Adding scratch and mar resistance to plastic
  • Producing desired wood and metal finishes
  • Creating special effect such as soft feel and gloss matting
  • Controlling lubricity for high speed processing and rough service protection
  • Eliminating blocking in trim paints.

In both the paper and corrugated, and paint and coatings industries, Michelman incorporates stringent testing procedures allowing its customers to meet sustainability and compliance goals, as well as R&D and product development initiatives.

Repulpability Testing Procedure in Accordance with FBA Protocols

Repulpability Testing Procedure Followed by Michelman for Each Tested Coating per the FBA protocol entitled "Voluntary Standard for Repulping and Recycling Corrugated Fiberboard Treated to Improve Its Performance in the Presence of Water and Water Vapor."

The samples used for testing were sheets of 42 lb. liner board coated with a variety of Michelman coatings.*

Step 1 - Cut board into 1¼" (31.8 mm) by 4" (102 mm) strips.

Step 2 - Weigh out 0.55 lb. (25 g) of board.
Michelman note: This weight measurement must exclude moisture content using the following calculation (assume moisture content is 7%):
100% - 7% = 93%
25 g = 0.93(x)
26.9 = x
Conclusion: 26.9 grams of sample must be used for the test.

Step 3 - Place the sample in 1500 mL of 125 °F ± 10 °F (52 °C ± 3 °C).
Michelman note: Water should have a pH of 7.0. Hot tap water can be used provided the temperature is within the proper range, and sulfuric acid can be used to lower the pH level.

Step 4 - Preheat a modified one-gallon Waring blender (equipped with special blades) to 125 °F ± 10 °F (52 °C ± 3 °C).
Michelman note: Preheating the blender can be accomplished by running it under the same hot tap water used in Step 3.

Modified Waring blender

Step 5 - Blend the sample in the Waring blender at 15,000 rpm (low speed) for four minutes.
Michelman note: Holding the blender firmly in place, especially at the beginning of the cycle is recommended.

Special blades in Waring blender

Step 6 -Rinse all remaining fibers from the blender with 500 mL of hot water.
Michelman note: Pour the mixture from the Waring blender into a British disintegrator, also heated to 125 °F ± 10 °F (52 °C ± 3 °C).

Water running into the slotted, open screen box.

Step 7 - Deflake for five minutes in the British disintegrator (2000 ml total volume) at 3000 rpm.

Step 8 - Run the mixture on a 0.010 in. (0.254 mm) slotted open flat screen, maintaining a 1" water head for 20 minutes. Save the accepts and rejects in aluminum weighing pans.

Michelman notes: The fibers that pass through the screen are called the "accepts" and the fibers that accumulate on top of the screen are called "rejects."

To start the flow of water into the screener box, the water escape is first closed, and the flow for water entry opened, flooding the screen with water. Once the 1" (minimum) water head is achieved, the water escape flow is opened, and the water entry flow increased to equilibrate the system. Once the 1" water head is consistently maintained, the pulp mixture from the British Disintegrator is poured onto the screen. Ordinary tap water can be used to rinse the disintegrator canister and capture all of the mixture.

When the pulp is added, the flow through the water escape will slow and the water head will begin to rise. To compensate, the flow of water from the water entry will need to be slowed. Flow rates of the entry and escape hoses should be monitored and adjusted as necessary during the 20 minute period to maintain the minimum 1" water head.

As the test runs, water and some of the paper fiber will filter cleanly through the screen. This mixture is expelled through the water escape tube, with the fibers being captured in a sieve. The rejects will accumulate on top of the screen and not pass through to the collection sieve.

When 20 minutes has elapsed, the flow of water from the water entry is stopped, and the screen is entirely drained. The accepts are then removed from the sieve, scraping and using tap water to rinse (if necessary) to completely collect all material. The accepts can be hand wrung if necessary to remove any excess moisture, and are placed in a previously tared beaker for drying. The rejects are removed from the screen using a scraper and are also placed in a previously tared beaker.

Screen box, showing water entry, water escape with shut-off valve. Drying oven is shown in background (green).

Step 9 - Dry in a laboratory oven for 12 hours (± 4 hours) at 221 °F (105 °C).

Step 10 - Weigh the samples and record the net weights of the accepts and rejects. The following equation is then used to determine the % rejects.

The sample passes if the % of rejects is less than 15% rounded to the nearest 0.1%

* Before beginning the repulpability testing procedure, the moisture content of the treated sample must be measured as a percentage. The test must be run at least twice on each sample, and pass two out of three tests.

Source: Michelman

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Comments

  1. Menon Mannikum Menon Mannikum Mauritius says:

    Dear Sir,

    I am a producer of paper bag, I used MG Bleach and Brown Kraft Paper in reel, could you please inform me which product you can supply me to coat the paper.
    Thank you,
    Mannikum

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