# US 11,439,933 B2 · High capacity composite depth filter media with low extractables

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- Number: US 11,439,933 B2
- Document ID: US11439933B2
- Status: Granted
- Kind: B2
- Application number: 16/720,102
- Filed: 2019-12-19
- Published: 2020-04-30
- Granted: 2022-09-13
- Earliest claimed: 2013-08-30
- Assignees: EMD Millipore Corporation
- Applicants: EMD Millipore Corporation
- Inventors: Maybelle Woo; David Yavorsky; John Amara; Nripen Singh; Kwok-Shun Cheng
- Web page: https://patentgrep.com/patent/US11439933B2

## CPC

- B01D 39/1623: {of synthetic origin}
- B01D 29/66: by flushing, e.g. counter-current air-bumps
- B01D 39/163: {sintered or bonded}
- B01D 2239/0407: comprising particulate additives, e.g. adsorbents
- B01D 2239/0654: Support layers
- B01D 2239/086: Binders between particles or fibres
- 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)

## Abstract

A depth filtration device for the clarification of biological fluids including a composite depth filter media having a nonwoven first layer integral with a second layer containing a polyacrylonitrile (PAN) fibers, a filter aid, and a wet-strength resin. The depth filter media exhibits increased binding capacity for soluble impurities such as DNA and host cell proteins from biological/cell culture feedstreams during secondary clarification and low-level impurity clearance of harvested cell culture fluids, such as those used for the manufacture of monoclonal antibodies. The depth filter media additionally exhibits significantly lower flushing requirements, resulting in lower levels of organic, inorganic and bioburden extractables released, high dirt holding capacities and good chemical and/or radiation resistance.

## Claims

### Claim 1

A process for pre-use water flush of depth filters having lower bioburden comprising:
a. providing a synthetic composite depth filter media comprising at least two layers, wherein at least one layer comprises synthetic fibrillated polymeric fibers comprising polyacrylonitrile and/or polyacrylonitrile copolymers, and a synthetic filter aid comprising one or more of silica, alumina, glass, metal oxides or mixed-metal oxides, ion-exchange resins and carbon;
b. treating the depth filter media by,
i. irradiating the depth filter media at a dose of about 10 to 45 kGy; or
ii. flushing the depth filter media with 0.5 N NaOH for at 100 to 300 liters/m2/hr for 30 min., and
c. flushing the treated depth filter media with water at flow rates ranging from about 10 liter/m2/hr to about 600 liter/m2/hr such that the level of total organic extractables measured in the filtrate is about 0 to 3 ppm.

### Claim 2 (depends on 1)

The process of claim 1, wherein the at least one layer comprising synthetic fibrillated polymeric fibers comprising polyacrylonitrile or polyacrylonitrile copolymers, and a synthetic filter aid comprises at least 26% by weight of synthetic fibrillated polymeric fibers based on the total weight of the synthetic fibrillated polymeric fibers and filter aid.

### Claim 3 (depends on 1)

The process of claim 1, wherein the at least one layer comprising synthetic fibrillated polymeric fibers comprising polyacrylonitrile or polyacrylonitrile copolymers, and a synthetic filter aid comprises over 0 to 90% of the filter aid by weight based on the total weight of the synthetic fibrillated polymeric fibers and filter aid.

### Claim 4 (depends on 1)

The process of claim 1, wherein the synthetic composite depth filter media further comprises a wet strength resin, said wet strength resin comprising water-soluble synthetic polymers of urea or melamine-formaldehyde based polymers, polyaminopolyamide-epichlorohydrin (PAE) polymers or glyoxalated polyacrylamide (GPAM) resins.

### Claim 5 (depends on 4)

The process of claim 4, wherein the content by weight of the wet strength resin based on the total weight of the synthetic fiber and filter aid is over 0% to about 5%.

### Claim 6 (depends on 1)

The process of claim 1, wherein the synthetic composite depth filter media comprises at least one layer comprising a synthetic nonwoven or a microfiber layer, said synthetic nonwoven or microfiber layer comprising polypropylene, polyesters, polyethylene, nylon, polyacrylonitrile, carbon or glass.

### Claim 7 (depends on 1)

The process of claim 1, wherein a feed flow direction is from a first layer to a second layer.

### Claim 8 (depends on 7)

The process of claim 7, wherein the first filter layer is in direct contact with the second filter layer.

### Claim 9 (depends on 1)

The process of claim 1, wherein said level of total organic extractables (TOC) is 2.0 parts per million (ppm) or less.