CS272484B1 - Method of fibres production from secondary fibres from waste paper and from fibres from solid municipal refuse for asbestos replacement in fibre-cement composites - Google Patents

Abstract

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Description

1 CS 272 484 Bl

BACKGROUND OF THE INVENTION The present invention relates to a process for the production of fibers from secondary fibers, from papermaking paper and from fibers from solid household waste for the substitution of asbestos in fiber cement composites. In the production of fiber-cement composites, asbestos can be replaced by various inorganic and organic fibers, natural or synthetic fibers (Alternatives and asbestos products, Aujalena Publication Ltd., 1985). 2 inorganic can be glass and synthetic mineral fibers. For example, from synthetic organic fibers, it may be: aramid (I. I. Du Pont de Nemours and Co., Wilmington, Delaware USA), polyolefin (Du Pont de Nemours and Co., Wilmington, DelawareUSA), polyacrylonitrile (Hoechst AG , NSR), polyvinyl alcohol (Kuraray Co. Ltd., Oapon) and other fibers. Of the natural organic fibers, they are, in particular, fibrous cells made of wood, straw, and other metallic materials. Of the industrially produced products of the fibrous cell type, it is mainly pulp, semi-cellular and high-lignified fiber.

Ooposially used processes apply primary fiber fibers to fiber cement composites with all their disadvantages, such as: wood consumption for their production, associated environmental pollution in production, and high cost.

The above-mentioned disadvantages are eliminated by the method according to the invention, wherein an aqueous solution containing an alkali metal hydroxide or carbonate or bicarbonate is added to the waste paper or solid household waste and 10 to 20% by weight by addition of sulfite or sulfide. expressed as the oxide of the respective alkali metal and based on the weight of the absolute dry fibers with optional addition of the quinone catalyst, preferably anthraquinone in an amount of 0.05 to 1% by weight. based on absolute dry fibers, at a temperature of 100 ° C to 180 ° C for 30 to 90 minutes, at a ratio of secondary fibers to a solution of 1: 1 to 1 µl.

The pulp produced has good physical-mechanical properties and can be produced at low cost. EXAMPLE 1 An aqueous solution of 500 liters was added to 1000 kg of newsprint (suppressed), which contained 10 wt. % NaOH, expressed as sodium oxide, 4% by weight, and SO 3, 0.1% by weight. anthraquinone, all related to absolute dry harvesting. paper. The mixture was heated at 150 ° C for 35 minutes. After the batch, the leachate is removed by filtration, the fiber washed with water. The pulp obtained in this way has a yield of 4.5% and a strength of 150 kPa. Example 2

As Example 1, but without the addition of Na 2 SO 3. A fiber with a yield of 73%, a market share of 4.0 fcm and a strength of 130 kPa is obtained. Example 3

As example 1, but with 15 wt. % NaOH and 2 wt. Na 2 SO 3. A fiber with a yield of 66%, a lag of 5 km and a strength of 155 kPa is obtained. Example 4

As Example 1, only kraft boiling liquor containing 20 wt. active alkali (such as Na 2 O) at 25% sulfite. A fiber with a yield of 80% and a lag of 4 km is obtained.

The pulp thus prepared has properties corresponding to semi-chemical to chemical celluloses. Its physical-mechanical properties can be used as a substitute for asbestos in fiber-cement compositions.

Claims (3)

OBJECT OF THE INVENTION A process for the production of fibers from secondary fibers, recovered paper and solid household waste fibers for the replacement of asbestos in fiber cement composites, characterized in that an aqueous alkali metal solution is added to the recovered paper or solid household waste in an amount of 10 to 20% by weight. expressed as the oxide of the corresponding alkali metal and based on the weight of the absolute dry fibers, at a temperature of 100 ° C to 180 ° C for 30 to 90 minutes, at a ratio of secondary fibers to solution of 1: 1 to 1:10. 2. A process for the production of fibers from secondary fibers, recovered paper and fibers from solid household wastes for asbestos replacement in fiber cement composites according to point 1, characterized in that alkali metal hydroxide or carbonate or bicarbonate with added sulphite is used as the aqueous alkali metal solution; sulfide. 3. A process for the production of fibers from secondary fibers, recovered paper and fibers from solid household wastes for asbestos replacement in fiber cement composites according to items 1 and 2, characterized in that a quinone-type catalyst, preferably anthraquinone, is added in an amount of 0.05 up to 1% by weight based on absolutely dry secondary fibers.