A New Catalyst System for Cross-Linking Cotton Cellulose with Formaldehyde

Abstract

A dual catalyst system containing magnesium and fluoborate ions facilitates the cross-linking of cotton cellulose with formaldehyde. Compared with previous formaldehyde cross-linking processes, the dual catalyst system permits operating at lower temperatures, shorter curing times, and lower concentrations of formaldehyde to produce high and nonvariable wash-wear characteristics which are durable in home and commercial launderings. In addition, this dual catalyst system may be used to impart durable-press properties to cotton fabric by using either pre-cure, partial cure, or postcure techniques.The magnesium cation seems to be unique in the dual catalyst system, since other divalent cations, e.g., barium and zinc, do not act synergistically with fluoborate. The role of fluoborate is discussed and data are shown which indicate that boron trifluoride is the active species which accelerates the cross-linking reaction in the presence of magnesium. 14 Carbon tracer studies reveal that, under equivalent processing conditions, more formaldehyde is bound to cellulose by the dual catalyst system than by a single catalyst (magnesium chloride) system.

Fluoborates in Catalysis of Durable Press Finishing Treatments for Cotton Fabrics

“…Both Zn(BF4)2 and NaBF4 have calculated constants close to that reported for HF; the constant for Mg(BF4)2 is two orders of magnitude greater. Kravetz and Ferrante reported contributions of hydrolysis of NaBF4 to the acidity of the NaBF4: MgCl2 mixed catalyst system used in a 1:10 gfw ratio in crosslinking treatments with formaldehyde [8]. They state that the BF3 produced from hydrolysis reacts synergistically with MgCl2.…”

“…Sodium fluoborate, although not a highly efficient catalyst by itself [8,13], has been discussed previously for inclusion in mixed catalyst systems with magnesium chloride in DP finishing [4,8,9,13]. Both the classical treatment of sodium fluoborate [11,15] and recent textile literature [8,9,13] consider sodium fluoborate, the salt of a hard acid and a hard base, to be a neutral salt. The textile literature claims that it is activated in the presence of MgCl2 by Lewis acid activity [8].…”

“…Both the classical treatment of sodium fluoborate [11,15] and recent textile literature [8,9,13] consider sodium fluoborate, the salt of a hard acid and a hard base, to be a neutral salt. The textile literature claims that it is activated in the presence of MgCl2 by Lewis acid activity [8]. The other fluoborates used as catalysts, magnesium fluoborate and zinc fluoborate, salts of a hard acid and soft base, are expected to have acid properties.…”

A New Catalyst System for Improved Durable Press Properties of Cotton Fabric

“…The increased catalytic activity of a mixed catalyst system had been attributed to increased protonation during the reaction and consequent liberation of a strong volatile acid [7,12]. This concept was not acceptable to others on the grounds that, if the liberation of a strong volatile acid had been the main cause for increased effectiveness of a mixed catalyst system, there should be more loss in strength, which is contrary to the observation that the relationship between WRA and strength retention improves when a mixed catalyst system is used in place of a single catalyst [5,6,10,13,16]. Pierce and Frick made a detailed study of a mixed catalyst system (magnesium chloride hexahydrate and citric acid) and found that the mixtures exhibited more catalytic activity than either component used separately.…”