CS233656B1 - Method of refining of pulp for production of paper for electrolytic capacitor - Google Patents

Abstract

The present invention relates to a method for purifying pulps for the production of paper for the basic assortment electrolytic capacitors it must be made of fibrous raw materials, not containing sulphates, chlorides, Na and Ca salts and Fe or Cu, which substances shorten lifetime of the capacitor. Ammonium salts do not matter in these papers phosphoric acid. Due to ion exchange the properties of cellulose cannot be expedient especially cellulose cations removed washing with water. After acidification with acid phosphoric is the removal of cations i anions by washing.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for cleaning paper pulp for a basic range of electrolytic capacitors.

The known paper making processes for the basic range of electrolytic capacitors are based on two basic raw materials, namely cotton raw material or bleached pulp. However, numerous problems arise in the processing of these raw materials. The cotton raw material is of varying quality and is highly contaminated. However, even its replacement with bleached pulp, which has recently been introduced in production, does not eliminate the difficulties of producing these special papers, since the import of pulps of the prescribed types is not always guaranteed in the same quality due to the fluctuations in the properties of the fibrous raw materials used.

Increasing the requirements for the properties of electrolytic capacitor papers also inevitably leads to an increase in the demands on the properties of the electrolytic capacitor papers and the maximum stabilization of these properties. Fluctuations in the properties of electrolytic capacitor papers contribute to increasing the scrapability of the capacitor coils, which has a negative effect on the failure rate of the devices into which the capacitors are mounted.

The main causes of scrap capacitors are also discussed in the literature. E.J.Smoljaninova in the journal Bumažnaja promyšlennost, vol., 1973j č, l, pp. 6-8 points to the uneven pore size as one of the reasons for rejection, and also in the same article points out that

233 658 washing the pulp with water places great demands on the quantity and purity of the washing water and is ineffective because the pulp contains mainly cations #

Another reason for rejection is dealt with AjF ^ Tiščenko et al., In the journal Bumažnaya promyšlennost roč, 1974, Č, 9 pp. 8-9 and the number 12, pp. 8-9. The authors describe the emerging presence of alkali salts of sulphates and chlorides, as well as the presence of metals (Fe, Cu), which shorten the lifetime of the capacitors and impair their properties. Also frequently occurring calcium and magnesium compounds cause scrap. Their negative influence is described in Bumažnaja promyšlennost roč, 1976, No 2, p. 17-18 also by the collective A ^ F ^ Mischief ·

The aforementioned drawbacks are eliminated by the pulp cleaning process of the invention. Its essence is that the sulphate or sulphite, bleached or unbleached coniferous pulp is treated with phosphoric acid in a dilute solution at a concentration of 1 to 10%, releasing ionically • These pollutants released from the pulp are then washed with deionized water. Then, the pulp is processed in a grinding line to a grinding stage that meets the density requirements of the paper produced, is stripped of the non-fibrous components in the knotter and processed without any additives on a paper machine ·

The small phosphate ion residues that remain in the pulp no longer compromise the capacitor's function or life.

Using the pulp cleaning method, it is possible to produce papers for the basic range of electrolytic capacitors even under conditions where the import of special natural fibers added to wood pulp is completely

233 658 unavailable. This cleaning method also fully replaces the previously used sophisticated pulp washing method. Example.

The kraft pulp in a 4% slurry was acidified to pH 3 with phosphoric acid. After homogenizing the slurry, the pulp was dewatered on a filter - washed with deionized water by re-pulping and dewatering. The pulp was then milled to 40 ° SR. The ground pulp was drained into a working vat, diluted with pure water to a concentration below 0.5% and processed on a self-scanning paper

15 g / m, with a porosity above 0.7.

Properties of finished paper and content of Cu .... 0,001%

0,004% content Pe content C.1

0.0005%.

Permeability factor / 2.8.

Claims (1)

SUBJECT OF THE INVENTION 233 6ŠB Process for cleaning sulphate or sulphite unbleached or bleached softwood pulps before processing on a paper machine for a basic range of electrolytic capacitors, characterized in that the pulp is treated with phosphoric acid in a dilute solution at a concentration of 1-10% and then released the pollutants are washed out with deionized water.