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Alkenyl Succinic Anhydride (ASA) is a sizing agent used in papermaking to increase the water repellency of paper. Almost 60 years after the introduction of the chemical in papermaking, scientists still have differing views on how ASA interacts with cellulose. Several experiments were conducted to bring more clarity to the ASA sizing mechanism, especially on the contentious question of ASA-cellulose covalent bonding or the esterification reaction between ASA and cellulose during papermaking. Herein, research papers and patents, including experiments and results, from the 1960s to 2020 were reviewed. Our investigation revealed that the ester bond formation between ASA and cellulose is insignificant and is not a prerequisite for sizing effectiveness; the main ASA-related material found in sized paper is hydrolyzed ASA or both hydrolyzed ASA and ASA salt. In addition, ASA emulsion stability and ASA emulsion retention are important for sizing efficiency improvement. [ABSTRACT FROM AUTHOR]

Alkenyl Succinic Anhydride (ASA) is a sizing agent used in papermaking to increase the water repellency of paper. Almost 60 years after the introduction of the chemical in papermaking, scientists still have differing views on how ASA interacts with cellulose. Several experiments were conducted to bring more clarity to the ASA sizing mechanism, especially on the contentious question of ASA-cellulose covalent bonding or the esterification reaction between ASA and cellulose during papermaking. Herein, research papers and patents, including experiments and results, from the 1960s to 2020 were reviewed. Our investigation revealed that the ester bond formation between ASA and cellulose is insignificant and is not a prerequisite for sizing effectiveness; the main ASA-related material found in sized paper is hydrolyzed ASA or both hydrolyzed ASA and ASA salt. In addition, ASA emulsion stability and ASA emulsion retention are important for sizing efficiency improvement.

The binding mechanisms of two reactive sizing agents, alkenyl succinic anhydride (ASA) and maleated sunflower oil high-oleic (MSOHO), with cellulose were studied. While ASA is produced from olefins out of fossil resources, MSOHO is a green sizing agent based on renewable plant materials. In contrast to common assumptions, that ASA is mostly covalently bound to cellulose, this study showed the largest part of ASA to be bound only by physisorption and only a rather small fraction, typically about 0.5 %, to be covalently attached by ester bonds. In the case of MSOHO, the covalent binding was only slightly higher, with about 3 % of the total amount being covalently linked. In both cases, covalently bound sizing agents were found to be almost uniformly distributed over the whole DP range of the cellulose as seen by carboxyl-selective fluorescence labeling in combination with size exclusion chromatography ('FDAM method'). [ABSTRACT FROM AUTHOR]

Alkenyl succinic anhydride (ASA) is a widely used paper sizing agent that is applied in the form of oil-in-water (o/w) emulsions in order to impart a water-resistant character to the resulting paper. To obtain stable o/w emulsions of ASA, laponite, a highly hydrophilic synthetic clay, was selected as the stabilizer after it had been modified with tetramethylammonium chloride (TMAC), a quaternary ammonium salt with the shortest possible hydrocarbon groups. It was found that the TMAC moderately neutralized the negative charges of laponite particles, lowered the apparent viscosity, but enhanced the turbidity of laponite aqueous dispersion by enhancing the hydrophobicity of the laponite particles, favoring adsorption of laponite particles on the ASA-water interface. Meanwhile, the TMAC significantly decreased the interfacial tension between ASA and water/aqueous laponite dispersion, promoting the formation of an emulsion with small droplets. When the added amount of TMAC reached 1wt% based on laponite, the as-prepared ASA emulsion had small droplet size, low viscosity and uniform droplet size distribution, and exhibited good creaming/coalescence stability. By using TMAC to modify laponite nanoparticles, the hydrolysis stability and sizing performance of ASA emulsion were also improved. [ABSTRACT FROM AUTHOR]

The sizing efficiency of maleated high oleic sunflower oil (MSOHO), a green reactive sizing agent, was studied in various sizing tests. MSOHO can be applied in the papermaking process according to protocols that are commonly used for the currently popular alkenyl succinic anhydride (ASA) sizing. While an adequate degree of sizing was reached with pure MSOHO, blends of MSOHO and fatty acid anhydride (FAA), another green sizing agent, gave even better results, coming close to the efficiency of pure ASA. Although both pure sizing agents - FAA as well as MSOHO - lack some efficiency when compared to ASA, blending those two sizing agents at an optimum ratio closes this gap with respect to ASA. This synergism was not caused by simply decreasing the viscosity of MSOHO. Blends of ASA-MSOHO and ASA-MSOHO-FAA were proposed for full-scale mill trials. [ABSTRACT FROM AUTHOR]

Maleated oils derived from high oleic sunflower oil (MSOHO) have promising applications in paper sizing as a green alternative to conventional reactive sizing agents, such as alkenyl succinic anhydride. In this study, MSOHO was comprehensively characterized analytically by attenuated total reflection infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy with full resonance assignment, and mass spectrometry. [ABSTRACT FROM AUTHOR]

The hydrolytic stability and sizing behavior of a new paper sizing agent based on renewable vegetable oils (maleated sunflower oil, high oleic: MSOHO) was compared to two conventional alkenyl succinic anhydride (ASA) specimens, a commercial sample, and a reagent-grade ASA sample. At various pH conditions as well as upon addition of Ca2+ ions, MSOHO was more stable than both ASA samples. This superior stability of MSOHO was also supported by zeta potential measurements over 1 week. Whereas for sizing of paper higher dosages of MSOHO were needed to gain certain water repellency as compared to the ASA samples, the addition of alum had a pronounced positive effect on the sizing efficiency of MSOHO. The higher stability of MSOHO made it possible to size with an MSOHO-starch emulsion that was aged for one day at room temperature, when conventional ASA-starch emulsion had long lost any sizing efficiency. [ABSTRACT FROM AUTHOR]

Natural oils derived from linseed, rapeseed, soybean, and a special breed of sunflower were tested for the production of maleated fatty oils for paper sizing in the ene-reaction with maleic anhydride. All these maleated oils were subjected to a conventional sizing test proving their ability to hydrophobize handsheets. Natural oils having only monounsaturated fatty acid residues (oleic acid) in the triglycerides worked best by having lower product viscosity and higher yields. The optimized production procedure employs antioxidant addition, an increased maleic anhydride:triglyceride ratio of 4:1, as well as increased pressure to reduce undesired polymeric byproducts and to increase yield. [ABSTRACT FROM AUTHOR]