Filter for brewed beverages, especially coffee filter, and proce

Details Filter for brewed beverages, especially coffee filter, and proce Filter for brewed beverages, especially coffee filter, and proce

1997-03-11

1999-02-16

Walker, W. L.

Liquid purification or separation

Filter

Supported, shaped or superimposed formed mediums

156 628, 156148, 55487, 428218, B01D 3908

Patent

active

058716440

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a filter for brewed beverages, especially a coffee filter, having pores and a process for producing such a filter.
2. Description of the Related Art
Coffee filters made of paper are known, such as the filter bags "Filtertuten.RTM." of the applicant. These coffee filters are made of crepe paper in order to increase their surface and have pores which are not or hardly detectable with the naked eye. The German Utility Model 69 39 904 describes coffee filters with a pore size of between 5 .mu.m and 20 .mu.m which allow aromatic colloidal particles to pass through the filter.
Documents DE 28 02 240 (laid open), DE 34 34 687 (laid open), DE 36 42 898 (laid open) and DE 41 35 660 (laid open) relate to coffee filters of a sheet-type material made from plastics or metal having sharp-edged holes or pores.
It is the object underlying the present invention to provide a filter for brewed beverages, especially a coffee filter, which is easy to produce and which improves the filtrate, such as coffee, as well as a process for the production of such a filter.


SUMMARY OF THE INVENTION

This object is achieved by means of a filter and a process for producing a filter according to the patent claims.
The idea underlying the invention is to provide a filter for brewed beverages, especially a coffee filter, made from blotting paper-like, web-like or fibrous material having pores with an average pore width of at least about 0.1 mm measured at a fiber density of about 50% of the original or average fiber density of the material; the average maximal pore width is preferably from about 0.6 to about 0.7 mm and more preferably from about 0.3 mm to about 0.4 mm. A range of an average pore width of from 0.15 to 0.25 mm is especially preferred.
The terms original or average fiber density of the filter material relate to the fiber density of the material prior to the formation of the mentioned pores and the average fiber density of the material throughout the entire filter surface, respectively.
A filter according to the present invention is produced from suitable papers and non-woven fabrics made from natural and/or synthetic cellulose-based fibers and/or from fibers of synthetic polymers as well as from mixtures of the mentioned fibers. The weight per unit area of preferred materials is about 10 to about 100 g/m.sup.2. The fibrous material is preferably filter paper as it has already been used for the filter bags "Filtertuten.RTM.". After the formation of pores in this material, which is preferably carried out by means of needles or water jets, the margins or edges of the pores are not sharp but, due to the fibrous material, irregular or "frayed" or porous.
Pores of such a size are particularly easy to produce and in particular improve the flavor of the coffee filtrate. Despite their relatively large average pore width, these pores surprisingly also filter powder particles such as coffee particles which are of a markedly smaller size, down to 10 .mu.m. This effect is probably due to the relatively large capillary forces acting at the dull edges of the pores.
The formation of pores with average pore widths of larger than about 0.1 mm increases the filtration performance or flow rate of the filter. This way, clogging or overflowing of the filter, in particular in coffee machines, is avoided. In addition, due to the larger pores in the filter considerably more colloidal aromatic particles can pass through the filter and alkaloids, such as caffeine, which are easily absorbed by conventional paper filters during the brewing of coffee, are not held back as they are in conventional paper filters. This way, the flavor of the filtrate, in particular during the brewing of coffee, is enhanced.
When fibrous material with such large pores is used, the possible swelling of the filter material does not impair the flow properties of the filter to such a marked extent as it does in conventional filter papers.
The increase of the pore width compared to conventional paper co

REFERENCES:
patent: 3360132 (1967-12-01), Harvith
patent: 3719282 (1973-03-01), Schwartz
patent: 4279630 (1981-07-01), Nakamura et al.
patent: 5143767 (1992-09-01), Matsuura et al.

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