DE2450919A1 - FILTER PAPER - Google Patents

Description

Patent attorneys Dlpl-lng. RBEET Z «en! Dlpl-Ing. K. LAMPRECHT

Dr..lng. R. BEETZJr. • Munich 22, Stelnedorfetr. 1 2450919

078-23.341P October 25, 1974

WIGGINS TEAPE RESEARCH & DEVELOPMENT LIMITED, London

(Great Britain)

Filter paper

The invention relates to highly effective air filter papers.

Papers for high efficiency air filters are mainly used to filter out particles below the used to-area from air.

The resistance to air flow or the pressure loss of the air filter paper is determined by the effectiveness of the paper and also determined by the physical properties of the paper sheets or sheets. In the case of very bulky paper, the pressure loss is low, but the paper is very soft and inclined for the delivery of loose fibers and dust. A dense paper has too high a pressure loss, but has good strength.

An ideal filter paper accordingly combines maximum effectiveness with low pressure loss sufficient strength and good dust retention capacity.

509818/0927

078- (45067) -SFBk

The invention provides a filter paper containing 15 - 95 wt .- ^ cotton linters or pulp or mercerized pulp, and 5-50 wt -.% Containing micro-glass fibers having a diameter from 0.05 to 1.49 / order, the Linters or the pulp or cellulose have a density of 0.5-0.4 and a Potts porosity of over 30000 ml / min based on an air-dried sheet of 60 g / m made of unground fibers.

Highly effective air filters with a very good filtration effect can be produced from this filter paper combine with low air resistance, the presence of cotton linters being the bulk good properties confers.

In a preferred embodiment of the invention, the filter paper contains up to 30 wt .- ^ solid cellulose fibers from a Potts porosity over 10,000 ml / min,

pulled onto a 60 g / m air dried sheet of unground fibers.

The addition of solid cellulose fibers results in highly effective air filters with very good filtration efficiency, combined with a low degree of fraying and sufficient strength.

The solid cellulose fibers can come from kraft pulp, from manila , eucalyptus or grass fibers.

On the other hand, the filter paper can be given additional strength by adding chemical binders will. Preferred chemical binders are starch, dextrin, carboxymethyl cellulose derivatives, polyvinyl

509818/0927

alcohol or cross-linking acrylic latex.

The invention is explained in more detail below with reference to production examples for filter paper.

example 1

45.5 kg of micro glass fibers (manufacturer Johns Manville, grade 106; fiber diameter 0.5-0.749 / μm) were processed with water in a hollander. The knife roller was set to a position about 3/4 down; After a processing time of 1 hour, the pH was lowered to 4 by adding dilute sulfuric acid. After a further processing time of 30 minutes, the glass fibers were well dispersed. The glass fibers were then tested using the Montigny sieve test method. In this method, a sheet-making paper machine (British Standard Sheet Making Machine), which has a sieve plate with 1 mm thick rods attached at a distance of 5 mm, instead of wire, and a Büchner funnel provided with a filter paper are used. A 400 ml sample of the pulp was processed into a sheet in the sheet paper machine, dried and weighed (yg). A sheet was then produced from a further 400 ml sample by dewatering the pulp on the filter paper in the Büchner funnel. The weight of the fiber mass was denoted by χ g. The ratio ^. 100 is the so-called modified sieve value and should be between 6 and 12 % when using glass fibers of the above specification (grade 106). In the present example, the modified sieve value was $ 10>. 98.5 kg of short-fiber cotton linters with a density of 0.3 were some

50981 8/0927

Minutes, 30.5 kg Kraft wood pulp mixed with water or slurried for 20 minutes. The micro-glass fibers, cotton linters and wood pulp (26 wt -.% Micro-glass fibers, 56.5 wt .- ^ cotton linters, 17.5 fo Kraft wood pulp) were then mixed together and run on a Fourdrinier paper machine at a speed of 10 m / min a fiber paper web of 105 g / m processed. The paper was dried, wound up and then tested for pressure loss and penetration. The pressure loss was 5 * 5 mm water column with an air flow of 1.5 m / min and the penetration 1 %, measured with a sodium chloride flame photometer with the same air flow (corresponding to the British Standard Test 4400).

Example 2

75 kg of micro glass fibers (manufacturer Johns Manville, grade 106, fiber diameter 0.5-0.749 / μm) were processed with water in a hollander. The knife roller was set to a position about 3/4 down; After a processing time of 1 hour, the pH was lowered to 4 by adding dilute sulfuric acid. After a further 30 minutes processing time, the glass fibers were well dispersed. 175 kg of cotton linters with a density of 0.3 were processed with water in a Hollander for 20 minutes. The micro glass fibers and the cotton linters (30 wt .- ^ micro glass fibers, 70 wt .- % cotton linters) were mixed together and this fiber mixture 9 1 PRIMAL HA 16 and 2.2 1 PRIMAL P 206 (both products acrylic latices, manufacturer Rohm and Haas, UK Ltd .) added. The slurry of fibers and latex was then processed into a fiber paper web on a Fourdrinier paper machine at a speed of 10 m / min, dried and wound up.

509818/0927

The paper was then tested for pressure loss and penetration. The pressure loss with an air flow of 1.5 m / min was 11.0 mm water column, the penetration 0.08 10 _s measured with the same air flow with a sodium chloride flame photometer (corresponding to the British Standard Test 4400).

Example 3

91 g microglass fibers (made by Johns Manville, grade 106, fiber diameter 0.5-0.749 μm) were processed in a hollander as described in Example 1. In the present example, the modified sieve value as in Example 1 was 10 %. 10 kg of short-fiber cotton lint with a density of 0.3 were mixed with water for a few minutes and 34 kg of Kraft wood pulp for 20 minutes. The micro-glass fibers, cotton linters, and the Kraft wood pulp (40.5 wt -.% Micro-glass fibers, 44.4 -.- wt -.% Cotton linters, 15.1 wt -.% Kraft wood pulp pulp) were mixed together and equal to the Way as described in Example 1 to a fiber paper

web of 105 g / m processed.

The paper was then tested for pressure loss and penetration. With an air flow of 1.5 m / min, the pressure loss was 15.5 mm ViS, the penetration 0.025 fo (corresponding to the British Standard Test 4400).

50981 8/0927

Claims (8)

- β claims ( 1J filter paper, characterized by 15 - 95 wt .- ^ cotton linters or mercerized pulp or cellulose and 5 - 50 wt .- % micro glass fibers of 0.05 - 1 * 49 / um diameter, the linters or pulp having a density of 0 , 3 - 0.4 and have a Potts porosity of over 30000 ml / min, based on an air-dried Sheets of 60 g / m made of unground or unground fibers. 2. Filter paper according to claim 1, characterized by up to 30 wt .- ^ solid cellulose fibers with a Potts porosity of over 10,000 ml / min, based on an air dried sheets of 60 g / m from unground fibers. 3. Filter paper according to claim 2, characterized by Kraft wood pulp, manila, eucalyptus or grass fibers than cellulose fibers. 4. Filter paper according to one of claims 1-3 * characterized by a chemical binder. 5. Filter paper according to claim 4, characterized by starch, dextrin, carboxymethyl cellulose derivatives, polyvinyl alcohol or cross-linking acrylic latices as chemical binders. 6. Filter paper according to claim 2, characterized by 26 wt. -Fo micro glass fibers with a fiber diameter of 0.5-0.749 / um, 56 * 5 wt .- ^ cotton lint of density 0.3 and 17.5 wt .- ^ Kraft- Wood pulp pulp. 609818/0927 2A50919 7. The filter paper according to claim 1, characterized by 30 wt -fo Mikrogl as fibers having a fiber diameter of 0.5 -. 0.749 / um and 70 wt -.% Cotton linters the density of 0.3. 8. Filter paper according to claim 2, characterized by 4-0.5 wt .- ^ microgl as fibers with a fiber diameter from 0.5-0.749 / µm, 44.4% by weight cotton linters Density 0.3 and 15.1 wt .- ^ Kraft wood pulp. 509818/0927