# US 2014/0360145 A1 · Filter medium for filter, method for producing the same, and filter

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- Number: US 2014/0360145 A1
- Document ID: US20140360145A1
- Status: Published application
- Kind: A1
- Application number: 14/362,727
- Filed: 2012-09-25
- Published: 2014-12-11
- Earliest claimed: 2011-12-19
- Assignees: Teijin Limited; Mahle Filter Systems Japan Corporation
- Applicants: Mahle Filter Systems Japan Corporation; Teijin Limited
- Inventors: Yuichi Hamada; Mitsutoshi Suzuki; Hiroyuki Ishii; Kenji Inagaki
- Web page: https://patentgrep.com/patent/US20140360145A1

## CPC

- F02M 35/02458: {consisting of multiple layers, e.g. coarse and fine filters; Coatings; Impregnations; Wet or moistened filter elements}
- B01D 39/16: of organic material, e.g. synthetic fibres
- B01D 39/163: {sintered or bonded}
- B01D 39/18: the material being cellulose or derivatives thereof ({cork or peat B01D39/1646} ; making filter paper D21F11/14)
- D04H 1/4374: using different kinds of webs, e.g. by layering webs
- D04H 1/43828: {sheath-core}
- D04H 1/4383: {sea-island}
- D04H 1/43835: {Mixed fibres, e.g. at least two chemically different fibres or fibre blends}
- D04H 1/43838: {Ultrafine fibres, e.g. microfibres}
- D21H 27/08: Filter paper (self-supporting filtering material B01D39/14; making on paper-making machines D21F11/14)
- D21H 27/30: Multi-ply (for surface covering D21H27/18; making on paper-making machines D21F9/00, D21F11/00)
- F02M 35/024: using filters, e.g. moistened (F02M35/026 takes precedence; cleaning of the filtering material F02M35/08)
- B01D 2239/025: comprising nanofibres
- B01D 2239/065: More than one layer present in the filtering material
- B01D 2239/086: Binders between particles or fibres
- B01D 2239/10: Filtering material manufacturing
- B01D 2239/1233: Fibre diameter
- F02M 35/02408: {Manufacturing filter elements}
- F02M 35/02441: {Materials or structure of filter elements, e.g. foams}
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- D04H: MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL (weaving D03; knitting D04B; braiding D04C; net-making D04G; sewing D05B; tufting D05C; finishing non-woven fabrics D06); FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING {; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION}(non-woven fabrics having an intermediate or external layer of a different kind, e.g. of woven fabric, B32B)
- D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR

## Abstract

Provided are a filter medium for a filter, which makes it possible to obtain a filter high in collection efficiency, low in pressure loss and long in filter lifetime, a method for producing the same, and a filter using the filter medium for a filter. A filter medium for a filter is used as a constituent member of a filter and composed of a wet type nonwoven fabric, wherein the filter medium for a filter has a multilayer structure of two or more layers, and there is no interface between the above-mentioned two layers.

## Claims

### Claim 1

A filter medium for a filter, which is used as a constituent member of a filter and composed of a wet type nonwoven fabric, characterized in that the filter medium for a filter has a multilayer structure of two or more layers and in that there is no interface between two adjacent layers of the multilayer structure.

### Claim 2 (depends on 1)

The filter medium for a filter according to claim 1, wherein the filter medium for a filter contains short-cut nanofibers composed of a fiber-forming thermoplastic polymer, having a single fiber diameter (D) of 100 to 1,000 nm and obtained by performing cutting so that the ratio (L/D) of the length (L) to the single fiber diameter (D) is within the range of 100 to 2,500.

### Claim 3 (depends on 2)

The filter medium for a filter according to claim 2, wherein the short-cut nanofibers are ones obtained by dissolving and removing a sea component from a conjugate fiber comprising an island component composed of a fiber-forming thermoplastic polymer and having an island diameter (D) of 100 to 1,000 nm and a sea component composed of a polymer more easily soluble in an alkaline aqueous solution than the fiber-forming thermoplastic polymer.

### Claim 4 (depends on 3)

The filter medium for a filter according to claim 3, wherein the sea component in the conjugate fiber is polyethylene terephthalate copolymerized with 6 to 12% by mole of 5-sodium sulfoisophthalic acid and 3 to 10% by weight of polyethylene glycol having a molecular weight of 4,000 to 12,000.

### Claim 5 (depends on 3)

The filter medium for a filter according to claim 3, wherein the island component in the conjugate fiber is a polyester.

### Claim 6 (depends on 3)

The filter medium for a filter according to claim 3, wherein the number of islands in the conjugate fiber is 100 or more.

### Claim 7 (depends on 1)

The filter medium for a filter according to claim 1, further containing core-sheath conjugate type binder fibers.

### Claim 8 (depends on 1)

The filter medium for a filter according to claim 1, wherein when the delamination strength between the two adjacent layers of the multilayer structure is measured with n=10, for the remaining 8 values except for the maximum value and the minimum value thereof, the ratio of the maximum value/the minimum value is 1.5 or more.

### Claim 9 (depends on 1)

The filter medium for a filter according to claim 1, wherein in both surfaces of the filter medium for a filter, when the number of fibers on a surface on which more fibers are exposed is taken as DL and the number of fibers on the other surface on which fewer fibers are exposed is taken as DU, the DU/DL ratio is 0.8 or less.

### Claim 10 (depends on 1)

The filter medium for a filter according to claim 1, wherein the basis weight thereof is within the range of 30 to 300 g/m2.

### Claim 11 (depends on 1)

The filter medium for a filter according to claim 1, wherein the thickness thereof is within the range of 0.5 to 4.0 mm.

### Claim 12

A method for producing a filter medium for a filter comprising (1) performing papermaking using a slurry for a first layer, (2) additionally putting a slurry for a second layer therein until the papermaking process is completed, and (3) further repeating the same operation as in the process of (2) also in a subsequent process as needed.

### Claim 13 (depends on 1)

A filter using the filter medium for a filter according to any one of claim 1.

### Claim 14 (depends on 13)

The filter according to claim 13, wherein the filter is an air filter for an internal combustion engine.