Paper internal sizing

Internal Sizing. The most widely used internal sizes are alkyl ketene dimers (AKD), alkenylsuccinic anhydrides (ASA), and rosin-based sizes that are used with papermaker s alum (aluminum sulfate with 14 waters of hydration), polyaluminum chloride (PAG), or polyaluminum siUcosulfate (PAS) (61). The rosin-based sizes are used under acidic conditions. Since the mid 1980 s there has been a steady conversion from acid to alkaline paper production, resulting in static to declining demand for the rosin-based sizing systems. Rosin is a complex mixture of compounds and consists primarily of monocarboxyhc acids with alkylated hydrophenan threne stmctures (62). A main constituent of wood rosin, gum rosin and taH-oil rosin is abietic acid. 

Internal reflection, 24 111-112 Beer s law expression for, 24 113 Internal resistance, batteries, 3 410 Internal return rate (IRR), 9 544-545 Internal sizing, in paper manufacture, 18 109-113... 

Internal sizing may be carried out over a wide pH range, but it is popular now to use neutral or slightly alkaline systems. When successfully performed, it retards the rate of penetration of a fluid through capillaries formed both within and between fibres. The fluid involved is, for most commercial grades of paper, water but resistance to non-aqueous fluids may also be important in some applications. This discussion will concern itself only with sizing against aqueous systems. 

Since the early days of machine made paper in the first half of the nineteenth century, the most widely applied method of Internal sizing has been the use of naturally occurring resinous materials ("rosins") in conjunction with an aluminium salt, usually aluminium sulphate (called "alum" by paper-makers). Various forms of rosin sizes (rosin soaps, rosin emulsions, fortified rosins) have been developed over the years to improve the process, but these variants still involve the use of alum as a means of ensuring that fibres retain a layer of size. 

Paper Sample Pulp Composition pH Internal Size... 

Paper specimens were obtained from Mead Paper, Printing and Writing Paper Division (Chillicothe, Ohio 45601). Samples were identified as being free from other materials, i.e., no preservatives, slimicides, defoamers, etc. Internally-sized samples were sized by conventional alum/rosin sizing surface-sized materials were prepared by an application of starch at the size press and all the other samples were unsized. Whatman filter paper was extracted with a 68/32 mixture of chloroform/acetone to remove any organic binder from the fiber surface. The fiber composition of the Whatman filter paper was identified by optical microscopy as cotton. The sample identified as "No Sizing" was... 

Table VI lists the relationship between the sample preparation and the amount of hydrocarbon (Cj) on the surface. Obviously, those samples with internal sizing added have an elevated hydrocarbon content. It is this hydrocarbon, in the form of rosin and rosin salts, that imparts the low surface energy and resistance to water penetration to the paper. In other cases, the hydrocarbon is probably in the form of lignin remaining from the pulping operation or adventitious carbon simply from the handling of the sample.

Chern. Descrip. Semirefined paraffin wax emulsion CAS 8002-74-2 EINECS/ELINCS 232-315-6 Uses Used for latex-based protective coating systems, wood coatings internal sizing applies, for wet processing provides exc. moisture barrier to paper, paperboard, building prods. 

Methacrylamidopropyltrimethylammonium, chloride Montan wax Potassium aluminate Sodium phosphoaluminate sizing, paper internal Starch, pregelatinized sizing, surface paper Starch, oxidized sizing, textiles... 

Seppanen, R., Tiberg, F. and Valignat, M. P., Mechanism of internal sizing by alkyl ketene dimers (AKD). The role of the spreading monolayer precursor, Nordic Pulp Paper Res. J., 15, 452-458 (2000). 

Schutz, R.A. Theoretical and practical aspects of sizing today and tomorrow. Proc. 3 Intern. Sizing Symp., Shirley Institute (Ed.) Manchester 1977, Paper n° 1 pp 1-9... 

Niemo L., Internal sizing of paper, in Papermaking Chemistry (Ed. Niemo L.), Tappi Press, Helsinki, 1999. 

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