Glyoxalated Polyacrylamide Composition for Paper Drainage and Strength
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Solution Overview
Problem
Conventional glyoxalated polyacrylamide (gPAM) resins used in papermaking suffer from drawbacks such as underperformance in difficult furnishes, particularly in terms of dewatering and drainage, and are inefficient in providing both high retention and dry strength.
Innovation Solution
A drainage-optimized additive composition comprising a glyoxalated polyacrylamide (gPAM) resin with a high weight average molecular weight (Mw) and tailored zeta potential, prepared in situ during papermaking, which is achieved by controlling the concentration of a cationic acrylamide prepolymer during glyoxalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional high molecular weight drainage aids are used, then drainage performance is improved, but dry strength deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the molecular weight (at least 5 MDa) and charge density (at least 0.5 mEq/g) of the gPAM resin, as well as the glyoxal-to-prepolymer ratio (0.5:99.5 to 45:55). These parameter optimizations enable the resin to achieve both excellent drainage performance and good dry strength, resolving the traditional trade-off between drainage rate and dry strength
Solution Approach 2:
The patent uses composite materials by creating gPAM resin through the chemical reaction of polyacrylamide prepolymer with glyoxal. This composite structure combines the high molecular weight characteristics of PAM for drainage with the crosslinked gel structure from glyoxal for strength enhancement, achieving both drainage efficiency and mechanical strength
2Strength
If conventional gPAM resins are used, then strength benefits are improved, but drainage performance deteriorates
Solution Approach 1:
The patent reverses the conventional approach by prioritizing drainage parameters first. It specifies molecular weight of at least 5 MDa and charge density of at least 0.5 mEq/g as primary parameters, with controlled glyoxalation degrees. This parameter hierarchy ensures drainage performance is optimized first, while maintaining sufficient strength through controlled crosslinking
3Productivity
If high charge density drainage aids are used, then drainage is improved, but retention deteriorates
Solution Approach 1:
The patent optimizes charge density to a specific range (at least 0.5 mEq/g but controlled through glyoxal-to-prepolymer ratios of 0.5:99.5 to 45:55). This controlled charge density provides sufficient drainage performance while preventing excessive charge that would cause over-flocculation and retention loss. The controlled crosslinking also maintains floc integrity for better retention
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition provides enhanced drainage and good dry strength to paper products, significantly improving papermaking processes by decoupling the molecular weight and charge of the gPAM resin from that of the prepolymer, thereby overcoming the limitations of conventional gPAM resins.
Implementation Method 1
conventional high molecular weight drainage aids can give excellent drainage and retention, but offer little to no strength benefits, and in some instances even result in a reduced strength due to over-flocculation
Implementation Method 2
Examples of functional additives include strength aids, e.g. for imparting temporary wet-strength (TWS), wet-strength (WS), and/or dry-strength (DS) to the final product
Data Source
AI summary
A drainage-optimized additive composition for papermaking is disclosed. The composition comprises an aqueous media and a glyoxalated polyacrylamide (gPAM) resin having a weight average molecular weight (Mw) of at least about 5 MDa. The composition comprises from about 1.95 to about 2.45 wt. % of the gPAM resin. A method of preparing the composition is also disclosed, and comprises preparing a cationic acrylamide (cAM) prepolymer having at least one predetermined property, and selectively glyoxalating the cAM prepolymer by controlling the concentration of the cAM prepolymer in the aqueous media during glyoxalation in relation to the predetermined property. The method may be carried out in situ during a papermaking process (i.e., as an on-site method). A process of forming paper with the composition also disclosed, and comprises combining the composition with the aqueous suspension of cellulosic fibers, forming the cellulosic fibers into a sheet, and drying the sheet to produce a paper.