Akzo N.v.

Akzona Incorporated

Arno Wegerhoff

Hans G Zengel

Heinz Beck

Walter Brodowski

Ernst Seeberger

Gerhard Steenken

Karlheinz Hillermeider

Dieter Frank

Hans-Dieter Achtsnit

Fibrous silicon dioxide material that is resistant to high temperatures, particularly in the form of mats or plates, is produced by dry-spinning water glass into water glass fibers, the water glass fibers being then transformed into silica fibers by treatment with aqueous acid or salt solutions that contain hydrogen ions. The silica fibers are thereupon treated with an agent that accelerates the formation of cristobalite from amorphous silica. Such agents include, in particular, alkali hydrogen phosphates, sodium acetate and solium chloride. The fibers are dried and dehydrated at temperatures above 600.degree. C., particularly between 950.degree. C. and 1050.degree. C., before or after treatment with the accelerating agent. There dehydration occurs after such treatment, the fibers are subsequently subjected to thermal aftertreatment. When subjected to 1500.degree. C. temperatures, the material thus obtained generally shrinks by less than 3%; it has very little tendency to become brittle and is particularly well suited for the fabrication of high temperature insulation material.

High temperature-resistant fibrous silicon dioxide material

Water-containing water glass fibers are disclosed, substantially free from non-alkaline compounds and having a water content of from about 15 to 30% by weight, a tear strength of from about 5 to 30 cN/tex, a ratio of alkaline oxide to silicon dioxide of from about 1:3 to 1:1.9, an amorphous structure and a density of from about 2 g/cm.sub.3 to 2.5 g/cm.sup.3. The fibers are preferably cut into lengths of from 1 to 40 mm. They may be used for subsequent production of silica fibers, a technique more advantageous than producing the latter from a melt containing SiO.sub.2 or by acid-leaching of glass fibers. The silica fibers are useful for producing wet webs, filter linings and reinforcing material.

Water-containing water glass fibers

Process for the production of silica fibers of the type in which alkali water glass is dry spun into water-containing alkali silicate fibers which are then contacted with solutions containing hydrogen ions for transforming into silica fibers, the improvement being dry-spinning glass free from non-alkaline compounds having a molar ratio of alkaline oxide to silic dry dioxide of from about 1:3 to 1:1.9 and a viscosity of about 10-700 Pa measured at 30.degree. C., at 10.degree.-50.degree. C. in a drying funnel of a temperature of more than 100.degree. C., at a discharge velocity of minimum 5 m/min.

Method for making silica fibers

Process for the production of water containing water glass fibers of the type in which alkali water glass is dry spun into water containing fibers, the improvement being dry-spinning water glass free from non-alkaline compounds having a molar ratio of alkaline oxide to silicon dioxide of from about 1:3 to 1:1.9 and a viscosity of about 10-700 Pa measured at 30.degree. C., at 10.degree.-50.degree. C. in a drying funnel of a temperature of more than 100.degree. C., at a discharge velocity of minimum 5m/min.

Flame resistant foam plastics of cellulose and kieselguhr or one of several types of mica such as roscoelite, lepidolite, biotite, phlogopite, vermiculite or muscovite where at least 80 percent by weight of the kieselguhr or the mica show grain sizes ranging from 0.4 to 650 microns and where the bulk density of the kieselguhr is less than 0.40 g./cc. and the bulk density of the mica is less than 0.37 g./cc.

Filled foams of regenerated cellulose and process for the manufacturing

A process for producing a hydroperoxide in highly concentrated form by oxidation of its corresponding liquid hydrocarbon with oxygen or an oxygen-containing gas while simultaneously subjecting the liquid reaction mixture to a carrier gas distillation to remove unreacted hydrocarbon with the carrier gas while withdrawing a portion of the liquid reaction mixture which is enriched in the hydroperoxide.

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Worth, Germany

Arno Wegerhoff