Dry Strength Agent Research Articles

Flocculation kinetics of precipitated calcium carbonate

When the percentage of filler in paper is increased, the optical properties are improved and the production cost lowered. However, fillers weaken paper strength by decreasing the fibre–fibre bonded area. Little is known about the optimum filler floc size or filler floc properties to allow developing optimum paper characteristics. Consequently, the kinetics of aggregation of scalenohedral precipitated calcium carbonate (PCC) filler was studied using various polymers (flocculants, coagulants and dry strength agents). The sodium salt of partially hydrolysed polyvinyl formamide copolymerized with acrylic acid (PVFA/NaAA) or C-starch lead to floc sizes, less sensitive to dosage within a certain range. Results from stability ratios correlate with PCC particle size. The change in particle size measured by photometric dispersion analysis (PDA) correlates well with the change in PCC particle size measured by light scattering/diffraction. Kinetic calculations show the orthokinetic aggregation times to be consistent with the experimental PDA results. The main uncertainty in the orthokinetic times is estimating the effective shear rate. It is proposed that the bridging surface area of PCC particles, the area which can form bonds between PCC particles or aggregates, should be used to study the kinetics of PCC aggregation, and not the total or projected surface area. In polymer induced aggregation, the PCC particle size increases to a plateau value with increasing polymer dosage. Two regions are most pronounced for C-PAM, PVFA/NaAA and A-starch. Region I corresponds to bridging flocculation. Region II is where the particle size reaches a plateau, and not the expected maximum predicted by classical polymer bridging theory or charge neutralisation theory, likely because of a competition between particle aggregation and polymer adsorption.

A Study on Improvement in Quality of Dry-strength Agents for Neutral Papermaking

A Study on Improvement in Quality of Dry-strength Agents for Neutral Papermaking

The use of CMC as a dry strength agent – the interplay between CMC attachment and drying

Article The use of CMC as a dry strength agent – the interplay between CMC attachment and drying was published on January 1, 2008 in the journal Nordic Pulp & Paper Research Journal (volume 23, issue 1).

Bonding between cellulosic fibers in the absence and presence of dry-strength agents – A review

Various hydrophilic polyelectrolytes, including cationic starch products, are used by papermakers to promote inter-fiber bonding and increase paper’s dry-strength. Thus, papermakers can meet customer requirements with a lower net cost of materials, more recycled fibers, or higher mineral content. In the absence of polymeric additives, key mechanisms governing bond development between cellulosic fibers include capillary action, three-dimensional mixing of macromolecules on facing surfaces, conformability of the materials, and hydrogen bonding. Dry-strength additives need to adsorb efficiently onto fibers, have a hydrophilic character, and have a sufficiently high molecular mass. Though it is possible to achieve significant strength gains by optimal usage of individual polyelectrolytes, greater strength gains can be achieved by sequential addition of oppositely charged polyelectrolytes. Superior strength can be achieved by in-situ formation of polyelectrolyte complexes, followed by deposition of those complexes onto fiber surfaces. Polyampholytes also hold promise as efficient dry-strength additives. Opportunities for further increases in performance of dry-strength agents may involve fiber surface modification, self-assembled layers, and optimization of the dry film characteristics of dry-strength polymers or systems of polymers.

The Effect of Wet-end Parameters on the Retention of Fines and Dry Strength Agent

The Effect of Wet-end Parameters on the Retention of Fines and Dry Strength Agent

実機の変動要因を考慮した紙力増強剤の開発と抄造条件の最適化

The tendency of the progress of highly utilization of recycled waste paper and closed system in the pulp and paper industries of Japan is growing bad to worse for the condition of paper machines. As such a worse condition, it is hard to get the effective performance for paper strength agent. As the countermeasures, it is important to clear the factor that influence on improvement of paper strength and select effective total system on efficiency of strength agents.In this paper, the situation of development on dry strength agents, the optimum condition of papermaking and finally, more effective application of paper strength agents are summarized.

板紙の共重合分岐型紙力剤の使用経験

For a few years, there is a tendency in paper industry that saving energy, increasing the rate of waste paper applied and making paperboard light-weight are making progress. Besides, we have seen that higher operating speed of paper machine for the improvement of productivity, and higher closed rate on waste water treatment in the paper making system. On the other hand, we can see variety of needs and demanding higher quality for paper board coming from the market at the same time. In order for paper mills to cope with such requirements, considering the tendency on environmental issue above mentioned, it is required to improve the quality and application know-how of dry paper strengthening agent.This is reported on the development of introduction and result of “Mix (anionic/amphibiatic PAM)” and its succeeding “Co-polymer of High-Density Dry Strength Agent” and described the summary.

ＰＡＭ系紙力剤の技術動向について

ＰＡＭ系紙力剤の技術動向について

Starch polyampholytes with amine and xanthate substituents: Characterization and application

In the reported experiments, starch polyampholytes (xanthated starch amines) that contained either diethylaminoethyl or 2-hydroxypropyltrimethylammonium ether and xanthate substituents were prepared, characterized, and evaluated as wet- and dry-strength agents in paper handsheets. In aqueous solutions, these xanthated starch amines (XSA), which had degrees of substitutions (D. S. ) of 0. 023-0. 33 amine and 0. 005-0. 165 xanthate, underwent intra- and interionic bonding at their isoelectric points to form soft flocculent precipitates. Properties of XSA resembled those of ″complex coacervates.″ Paper that was prepared from an unbleached kraft furnish treated with XSA (amine/xanthate molar ratios, from 1. 5 to 4. 0) had significantly stronger wet and dry strengths than paper treated with cationic starch amines typically used in commercial papermaking.

N-chloroamide Derivatives of Polymers as Strength Agent for Paper

Some polymers bearing amide groups can be readily converted into the corresponding N-chloroderivatives by treatment with hypochlorite in alkaline medium. The N-chloroamide groups have a high reactivity to the groups having an active hydrogen atom, such as alcohols, phenols, and amines. On this account, various polymer-derivatives bearing N-chloroamide groups were examined as wet-and dry-strength agent for papers. Remarkable increases in dry-and wet-strengths were obtained in low-grade pulp papers, such as news print paper, and in unbleached pulp papers by wet-end addition of the N-chloroamide derivatives of polymers. However, these additives were not so effective for bleached pulp papers. This fact suggests that the N-chloroamide groups can readily react with the unbleached fibers (probably with lignin), forming the closs-linkages between the fibers, and that they, however, can not easily react with the hydroxyl groups of cellulose. The combined use of the N-chloroamide derivatives with a polyamine (aminoethyl cellulose) brought about significant increases in the dry-and wet-strengths of the bleached pulp papers as well as in those of the unbleached pulp papers. This effect may be attributed to the carbamide linkages formed by the reaction of the N-chloroamide groups with the amino groups of the polyamine.