Paper strength

Dispersion at temperatures of 90—110°C is a common final step io European mills processiog wax-coated old cormgated containers. Dispersion temperatures less than 90°C are reported to reduce wax particle size to improve pulp drainage properties on paper machines while improving paper strength (45). Dispersion has been used to reduce hot-melt adhesive, plastic coating, and asphalt particle size. These low density particles can then be removed from the pulp by flotation (46). 

Excellent paper strength Poor pulp color... 

Lorencak, P., Stange, M., Niessner, M., and Esser, A. (2000). Polyvinylamaine a new polymer for increasing paper strength. Wochenbl. Papierfar. 128,14 18. 

Cationic starches are widely used as wet-end additives in the pulp and paper industry to enhance starch and filler retention during papermaking. Use of cationic starches increases paper strength and decreases biological oxygen demand (BOD) of paper mill effluent. Presently only cationic corn and potato starches are used by Canadian paper mills. The degree of substitution (DS) of normal, waxy, high-amylose barley... 

Cationic starch is a frequently-utilized retention aid, especially when paper strength improvement is a second objective.141,142 Low pH activates tertiary amino starch, but at pH 6 an amphoteric starch, and at pH above 7 a quartenary ammonium starch, will be needed. 

A novel sizing strategy utilizes a microparticle system that enhances retention.166 A representative example is a combination of cationic potato starch (DS = 0.04), a metallosilicate hydrosol and AKD. In an approach to combine elevated filler retention, effective sizing and high paper strength, calcium carbonate is reacted with a starch-soap complex and combined with AKD.167168... 

Starch is added to the papermaking furnish for a variety of applications paper formation control furnish drainage improvement filler and cellulose fines retention size retention internal paper strength improvement surface strength enhancement and reduction of waste water pollution. 

Most frequently, com or potato starches are used, but there are also applications of wheat starch, rice starch, tapioca starch and others. Recently, waxy maize starch has found commercial application in the manufacture of paper. Thermally dispersed or pregelatinized unmodified starches are used for paper strength improvement by addition to the furnish or by spraying onto the papermaker s wire. 

Table VI. Influence of Initial Paper Strength on Activation Energies...

Santucci, L., Report on Paper Strength and Stability, Joint Meeting of... 

Corte and Schraschek (444a) used IR shifts on deuteration of cellulose to calculate binding energy in paper sheets. The values were of the proper order of magnitude but lower than experimental results. These authors also review the theories of paper strength and conclude that H bonds play a major part in it. Other workers (1788, 2225, 2224) have studied the same problem. 

Flexural strength varies primarily with thickness. It also varies with the tensile strength of the paper on the side tested, but the paper used on any one product is reasonably uniform. The correlation coefficients on individual products show slight increases indicating that there may be some correlation with the variations in paper strength, but the changes are hardly significant. 

The combined correlation coefficient does increase significantly showing that nail pull resistance can be predicted reasonably well from core hardness and flexural strength. Since the major component of flexural strength variation is thickness, the correlation is really with core hardness and thickness. There may be a small effect of paper strength, but it is confounded with the effect of thickness. 

Modification of the atomic force microscope with feedback loops enabled force-extension curves for individual polysaccharide molecules to be measured under constantly increasing force (rather than constant displacement), in a nanoscale version of the INSTRON tester for measuring paper strength. ... 

GF Leatham, GC Myers, TH Wegner, RA Blanchette. Biomechanical pulping of aspen chips paper strength and optical properties resulting from different fungal treatments. TappiJ 73 3) 249-255, 1990. 

Amino ethers (either free, or preferably cationized) have a broad range of current and potential applications in paper manufacturing as coatings and sizes that improve paper strength, retention of pigments and dyes, the production of conductive coatings, textile finishes, and other uses,597.i689,2311,2316,2317,2320,2328,2332,... 

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