Amphoteric cationic polymers for controlling deposition of pitch and stickies in papermaking

Abstract

The present invention relates to a method and composition for controlling pitch and stickies deposit in a pulp and papermaking process using amphoteric copolymers of diallyldimethylammonium chloride (DADMAC) with acrylic acid and / or acrylamide and optionally a siliceous material.

Description

[0001] This application claims the benefit of Provisional Application No. 60 / 585,184, filed Jul. 2, 2004 and Provisional Application No. 60 / 662,755, filed Mar. 17, 2005.[0002] The present invention relates to a method for controlling pitch and stickies deposition in a pulp and papermaking process using amphoteric copolymers formed from the monomers diallyldimethylammonium chloride (DADMAC), acrylic acid and optionally acrylamide. The method may optionally further comprise the addition of a siliceous material. The pitch and stickies are found in mechanical pulps, recycled fiber, coated broke, white water and the like. The invention also encompasses a composition for pitch and stickies control in papermaking comprising the amphoteric copolymer and optionally, a siliceous material. BACKGROUND OF THE INVENTION [0003] The present invention is directed to the use of amphoteric copolymers or terpolymers of diallyldimethylammonium chloride (DADMAC) with acrylic acid and optionally acrylamid...

AI Technical Summary

Benefits of technology

[0052] The present inventors have discovered that a cationic amphoteric DADMAC polymer with a ratio of cationic charge to anionic charge greater t

Problems solved by technology

Homopolymers of DADMAC and polyamines with high cationic charge density are good for neutralizing anionic trash but have limited success for controlling pitch and stickies deposition.

Pitch and stickies are interfering substances in the wet end of papermaking that can affect both the machine runnability and paper quality.

Deposition of pitch and stickies often leads to defects in the finished product and paper machine downtime causing lost profits for the mill.

These problems become more significant when paper mills “close up” their process water systems for conservation and environmental reasons.

Unless the pitch and stickies are continuously removed from the system in a controlled manner, these interfering substances will accumulate and eventually lead to deposition and runnability problems.

These methods are, however, not commonly used together since they may conflict with each other.

However, pitch adsorbents such as talc can end up contributing to the pitch deposit problem if the talc / pitch particles are unable to be retained in the paper sheet with surfactants and water-soluble polymers.

Anionic trash consists of colloidal (pitch and stickies) and dissolved materials that adversely affect the paper making in a variety of ways through deposit formation or interference with chemical additives.

The patent does not teach use of the polyDADMAC for stickies containing pulps from recycled secondary fibers.

The Canadian patent is also limited to use of DADMAC homopolymer.

This process however, relates to retention and drainage, not pitch and sticky deposit control.

However, they may not carry sufficient charge and / or molecular weight to fix pitch and stickies complexes to the fiber.

If not strongly fixed to the fibers, the complexes will become concentrated in the system and will lead to deposition problems.

The search for polymer compositions which will prevent pitch and stickies deposition has met with limited success and is still ongoing.

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