Paper alkaline

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. 

Sodium chlorite has also been used for treatment and removal of toxic and odorous gases such as hydrogen sulfide and mercaptans. Chlorine dioxide from chlorite is also useful for microbial and slime control in paper mills and alkaline paper machine systems (164,165). The use of sodium chlorite in textile bleaching and stripping is well known. Cotton is not degraded by sodium chlorite because the oxidation reactions are specific for the hemiceUulose and lignin components of the fibers. 

No specific information on the possible effect of the synthetic sizes on permanence is available, and they are not mentioned in the standard 04), but it seems unlikely that they would be deleterious. Presumably they have been used in comnercial grades of neutral/alkaline paper subjected to accelerated ageing tests. In terms of general effects on paper, the synthetic sizes have a tendency to reduce the surface frictional properties of paper to a greater extent than rosin. For example, this makes it more difficult to stack piles of cut sheets without slippage. However, the effect is less noticeable when high proportions of chalk filler are used, because the blocky particles increase friction. 

While Barrow solved the main problem, there are other modes of degradation which must be considered. As an organic material, cellulose and paper can be easily oxidized. Very small amounts of the transition metals, compounds of iron, copper, and cobalt, under humid conditions can accelerate oxidation and embrittlement of paper. This type of degradation, as is shown later, does not show up in the dry-oven accelerated aging which Barrow used. Thus his alkaline papers, if they contained the oxidation catalysts, may not always have been permanent. 

Three alkaline papers performed well after 36 years of natural aging, but retention of properties was not as great as expected (24). 

The data show that pH is not the only indicator of stability of paper, and that folding endurance is not a universal method of measuring degradation. For example, one would have expected the three alkaline papers to have retained a much higher percentage of their initial folding endurance (26). 

The mechanism of the enzymes action in deinking is not well understood. The desired pH range for treating alkaline paper, which has become much more common than acid paper, is pH 7 to 8 to minimize degradation of the calcium carbonate. This is suited to the Humicola and Aspergillus cellulase enzymes, which are used in this appfication. 

Barrow measured the pH of many old pieces of paper and also measured their strength and found that alkaline papers were generally strong but acid... 

Chem. Descrip. Cone, polymeric surfactant Uses Defoamer for wet-end, size press, coating applies., alkaline paper machine systems... 

Uses Water resist, aid, abrasion resist, aid for neutral and si. alkaline paper coatings improves printability Features Lowformaldehycie... 

Uses Optical brightener for alkaline paper stock conditions and for paper coatings based on casein, casein/latex, and all-syn. binders Eeatures Cone. suitable for furnishes with unbleached pulp and ground-... 

Uses Optical brightener for alkaline paper stock conditions and for paper coatings based on casein, casein/latex, and all-syn. binders Features Suitable for furnishes with unbleached pulp and groundwood Regulat DOT nonregulated SARA 304/313 nonreportable Properties YeL-brn. liq. char, odor misc. with water sp.gr. 1.10-1.14 vise. 25 mPa s vapor pressure 20 mm Hg (20 C) m.p. < 10 C b.p. 100 C pH 9-10.5 anionic... 

Wang F, Tanaka H., Mechanisms of neutral-alkaline paper sizing with usual rosin size using alum-polymer dual retention aid system, 7 Pulp Pap. Sci, 27(1), 2001, 8-13. 

Skimmings (tall oil) n. Curd, not acidified or otherwise processed, skimmed firom the black liquor of the alkaline paper pump industry, from which tall oil is obtained. 

A simple procedure for the rapid determination of the total acidity in wines and fruit juices was patented by Holzbach (1936). He prepared alkaline pieces of filter paper corresponding to 0.05% to 0.01 % acid, which he added to the solution. Bromocresol was used as an indicator, and from the number of pieces of alkaline paper added the acidity was calculated. A simple blue patented German indicator, useful for aU except the medium-to-dark red wines, was employed by Larsen (1961). Indicators, such as acridine and umbeUiferone, which are fluorescent in ultraviolet light for the end point in the acidity determination, were proposed by Volmar and davera (1931). One advantage of these was that they can be used in red wines. 

Water molecules are so small and cellulose and so hydrophilic that this solution usually affords only temporary protection. Formaldehyde, glyoxal, polyethylen-imine, and, more recently, derivatized starch (50) and derivatized cationic polyacrylamide resins (51) have been used to provide temporary wet strength. The first two materials must be applied to the formed paper, but the other materials are substantive to the fiber and may be used as wet-end additives. Carboxymethylcellulose-calcium chloride and locust-bean gum-borax are examples of two-component systems applied separately to paper that were used to a limited extent before the advent of the amino resins. Today three major types of wet-strength resins are used in papermaking polyamide-polyamine resins cross-linked with epichlorohydrin (52) are used in neutral to alkaline papers cationic polyacrylamide resins cross-linked with glyoxal are used for acid to neutral papers and melamine-formaldehyde resins are used for acid papers. 

Uses All-purpose defoamer for solid and surfactant-stabilized aq, foaming systems, e,g, acid and alkaline paper machines, puipmiii screening, deinking operations, size press and calender sol ns, mill effluent systems Regulatory FDA compliance... 

Another group of effective sizes include alkyl ke-tene dimers (- fatty diketenes) and alkenylsucci-nic anhydrides. These products react with the OH-groups of the cellulose fiber. While rosin-based sizes can only by used in acid paper making processes, the cellulose-reactive sizes are used in neutral and alkaline paper making. The result is better sheet strength, reduced corrosion on the equipment, less salt in the effluent and better stability of the paper towards aging (archival paper). 

Pure, white CaCOa is used in a wide variety of products. For example, it is used in papermaking to impart brightness, opacity, smoothness, and good ink-absorbing qualities to paper. It is particularly suited to newer papermaking processes that produce acid-free (alkaline) paper wifh an expecfed shelf life of 300 years or more. CaCOs is used as a filler in plastics, rubber, floor tiles, putties, and adhesives, as well as in foods and cosmetics. If is also used as an antacid and as a dietary supplement for the prevention of osfeoporosis, a condition in which the bones become porous and brittle and break easily. 

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