CS254607B1 - Paper for filtering hydraulic fluids with a nominal efficiency of 12 µm - Google Patents

Abstract

The solution concerns the production of filter paper for hydraulic fluids. It solves the problem of removing glass granules, which cause serious operational difficulties in paper processing, while reducing material costs and maintaining all required functional parameters. The essence of the solution lies in replacing the original mixture of refined cellulose fibers, cotton linters and coarser glass microfibers with a diameter of 2.5 to 3.5 μm containing glass granules with a mixture consisting, in addition to bleached magnesium bisulfite pulp, of fine glass microfibers with a diameter of 0.8 to 2.1 μm without glass granules.

Description

The invention relates to filter paper for filtering hydraulic fluids with a nominal efficiency of 12 µm.

During processing, i.e. folding into inserts, the paper used so far, which is made of a mixture of refined pulp fibers, cotton liner and glass microfibers with a fiber diameter of 2.5 to 3.5 µm, results in a disproportionately high wear of the functional parts - heads - abrasion caused by the release of glass granules. These granules are contained in glass microfibers of relatively high fiber diameter, i.e. 2.5 to 3.5 µm. Therefore, the heads need to be replaced quite often, leading to high financial losses in paper processing. Preliminary removal of granules from the aqueous suspension prior to the actual production of the base paper has proved to be unreliable and not sufficient in all cases for long-term monitoring.

Another negative consequence of the occurrence of granules in the produced paper is the possibility of piercing the paper with these granules during folding and thus preventing the fulfillment of the utility function, eventually. releasing the granule during the actual function of the finished insert and then causing a failure (seizure) in the hydraulic circuit.

The problem does not solve the material for filtration of liquids in hydraulic circuits according to MS.

AO 228 178, since this material contains, besides cotton liners, highly refined pulp and glass microfibers with a fiber diameter of 0.8 to

1.2 .mu.m also glass microfibers having a fiber diameter of 2.5 to 3.5 .mu.m containing a higher percentage of glass granules. Another unfavorable phenomenon in the use of both the hitherto used paper and the possible use of the paper produced according to AO 228 178 is the fact that a significant part of the pulp part of the furnish is made of expensive raw materials.

These drawbacks are overcome by the hydraulic fluid filter paper produced in accordance with the present invention. Its essence is that it is made from a blend of fibers of bleached sodium bisulfite pulp and fine glass microfibers with a fiber diameter of 0.8 to 2.1 µm. In this case, a conventional sorting system in the line of the papermaking machine producing the paper is sufficient to remove any granules.

Example

A fiber blend is prepared comprising 99% by weight bleached magnesium bisulfite pulp and 1% by weight glass microfibers having a fiber diameter of 1.3 to 2.0 µm. After homogenization of the mixture, a paper having a basis weight of about 100 to 115 g / m 2 is produced on a paper machine with an oblique or longitudinal screen 2.

Further, the paper is impregnated with an ethanolic phenolic resin solution by conventional method 2 to achieve a total basis weight gain of about 20 g / m 2.

The paper produced in this way achieves at least the same functional properties as the paper produced so far. At the same time, its folding does not lead to wear of the heads of the folding mechanisms and the material cost of the raw paper production is significantly reduced. The solution according to the invention can be used for the production of materials for filtration of hydraulic fluids.

Claims (2)

Paper for filtering hydraulic fluids with a nominal filtration efficiency of 12 µm, characterized in that it consists of a mixture of 90 to 99.5% by weight of bleached magnesium bisulfite pulp fibers and 0.5 to 10% by weight of glass microfibers with a fiber diameter of 0.8 to 2.1 µm. 2. The paper of claim 1, further comprising 10 to 25% by weight of phenol formaldehyde resin based on the weight of the fibers.