Some properties of a glass used in paper manufacture

Abstract

The chemi cal durability, heterogeneou s equilibria, h ygroscopicity, pH response, disper·sal, and t hermal ex pa nsion characteristics of a fib er glass used in paper manufacture were inves tiga ted . The chemi cal durabili ty of t his gl as~, was found to be ver y poor between pH 2 and pH -2, apparently du e to the high alumina"and low silica composition. Above and below t his range t he chemical durability greatly improved , showing with t he interferom eter no detectable attack for expos ures of 6 hours at 80° C either in high concentrations of H 2 S04, or between pH 4 and pH 8. At a lkalinities above pH 8 t h e durabili ty again decreased as is characteristic of man y silica te gla sses. In a ddi tion, t he h eterogeneous equilibria at the solu Lion-glass interface, using Ag (NH 3lz+ ions as indi cator , showed t he fib er glass when leached at pH 4.1. to have an un even distribution of migratable ions between t h e negatively charged glass surface and ambient aqueoll s sol utions, to a greater extent t han m ost commercial gl a~se~. In acco rd wi th the very low h ygroscopici ty and poor chemical durabi lity, clcctrodes prcpa rcd fro m Lhis glass gave no defini te r esponse Lo h ydrogen ion activi Ly of the ambient solli tions. Thc di spersal ch aracteri stics of t he fib ers in aqueo us solu tions foll ow t he "cri t ical" poin ts indicated l ,by t h e chemi cal du rabili ty CllI'VC co vering t he range fr o m pH -8.1 to pH 11 .8. Th c a nnealing and softelling temperatures a s obtained from Lhe r es pective expansion cur ves \I'ere found to be higher fo r t he fi ber glass than for either P y rex 7740 or Kimble N 51-A.Th c chemi cal durabili ty data, t he acid t itrat ion of sodium Silicate, and t he di s persal-pH series a re consistent wi th t he fi ndin gs of O'Leary et al. in emphasizing p H 2.9 as a cri t ical co nditi on for Lhc m ost slI cccss ful produ ction of paper from fib ers o f t his glass.

Paper from Inorganic Fibers

“…7870 Madison Ave., Toledo 7, Ohio. 6 Mini mum and maximum average diameter allowable. Measured using Williams freeness tester or by an air-flow resistance check using a 1-gram or larger sample.…”

“…It is possible that some manufacturers have cured this problem with better design of AV6. DIAM., MICRONS 6 Many other grades available for papermaking 5R or 7R customarily used in these laboratories. c 7R grade not ordinarily used in papermaking, but in combination with other inorganic fibers has been found satisfactory.…”

Factors Affecting Preparation of Glass Paper

“…Interest in papers made from inorganic fibers has increased greatly in recent years. The unique properties of these papers as well as some of the factors involved in their preparation have been discussed by O'Leary and others (5)(6)(7). Some of the interrelationships among several groups of variables, which affect the preparation of paper, are indicated below.…”