Cellulosic pine pulps prepared using the sulphate method

Ingredients

Pine wood (Pinus sylvestris L.), NaOH, Na2S, H2O2, MgSO4, Na2SiO3, water

Preparation Steps

Original Recipe Text

Cellulosic pine pulps were prepared using the sulphate method. Materials were kept in a hermetically sealed container before treatment with NaOH and Na2S solutions (20–38% active alkali, water to wood ratio of 4). Delignification processes were conducted in 15 dm3 PD-114 stainless steel reactors with regulated temperature and agitation. Suspensions were heated for 120 min to achieve a temperature of 172 °C and incubated for a further 120 min. Suspensions were then cooled to 25±5 °C, washed with demineralised water, and incubated overnight (p. 3). Solids were disintegrated for 3 min in a laboratory JAC SHPD28D propeller pulp disintegrator, and fibers were screened using a 0.2 mm gap screen. For comparison, a completely bleached pine pulp was prepared using peroxide bleaching. The bleaching liquor consisted of 3% H2O2, 2.5% NaOH, 0.2% MgSO4, and 1% Na2SiO3. This mixture was held at 80 °C for three hours and manually mixed every 30 min (p. 3). Laboratory test sheets were formed in a Rapid–Koethen class apparatus according to PN-EN ISO 5269-2 (2007) with a basis weight of 80 g/m2 (p. 3).

Evidence

"Pine wood (Pinus sylvestris L.) was used in this work. Cellulosic pine pulps were prepared using the sulphate method described by Modrzejewski et al.52 from industrial woodchips containing 7–8% moisture."

Remarks

The study investigated the impact of lignin content (ranging from Kappa number 1 to 90) on the durability of paper produced in neutral environments (p. 2). Results observed no significant effect of lignin content on the ageing rate of paper produced at neutral pH (p. 1, p. 9). The degree of polymerisation (DP) of cellulose varied from 1074 (bleached) to 3273 depending on the delignification degree (p. 4). Mechanical tests revealed that unbleached papers lost 62.1–70.5% of their initial tear resistance after 90 days of accelerated ageing at 90 °C and 59% relative humidity (p. 5). The research challenges the historical consensus that lignin is the primary agent of paper degradation, instead highlighting that acidification from aluminum sulfate in acidic papermaking environments (pH 4.5–5.5) is the major cause of low paper strength in the 19th and 20th centuries (p. 2).