# US 12,760,168 B2 · Dual-function melt additives

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- Number: US 12,760,168 B2
- Document ID: US12760168B2
- Status: Granted
- Kind: B2
- Application number: 17/762,782
- Filed: 2020-10-15
- Published: 2022-12-01
- Granted: 2026-10-13
- Earliest claimed: 2019-10-16
- Assignees: 3M Innovative Properties Company
- Applicants: 3M Innovative Properties Company
- Inventors: Fuming B. Li; Nathan E. Schultz; John M. Brandner
- Web page: https://patentgrep.com/patent/US12760168B2

## CPC

- C08K 5/3475: condensed with carbocyclic rings
- B01D 39/163: {sintered or bonded}
- B03C 3/28: Plant or installations without electricity supply, e.g. using electrets
- C08J 5/18: Manufacture of films or sheets
- C08K 5/3477: Six-membered rings
- C08K 5/47: Thiazoles
- D04H 3/007: Addition polymers
- D04H 3/16: with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
- D06M 10/025: {Corona discharge or low temperature plasma}
- B01D 2239/0435: Electret
- B01D 2239/0442: Antimicrobial, antibacterial, antifungal additives
- B01D 2239/0622: Melt-blown
- C08J 2323/12: Polypropene
- D06M 2101/18: Synthetic fibres consisting of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D10B 2505/04: Filters
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- 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)
- B03C: MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS (separating isotopes B01D59/00; combinations of magnetic or electrostatic separation with separation of solids by other means B03B, B07B)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- 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)
- D06M: TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D10B: INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES

## Abstract

Charged polymeric webs, such as electret webs, include a thermoplastic resin and a charge-enhancing additive. The charge-enhancing additive is a dual-function charge-enhancing additive that enhances the charge of the electret and also has anti-microbial properties. The additives are substituted-benzimidazole or substituted-benzothiazole compounds. The electret webs may be a non-woven fibrous web or a film. The electret webs are suitable for use as filter media.

## Claims

### Claim 1

An electret web consisting of:
a thermoplastic resin consisting of polyolefin; polyvinyl chloride; polystyrene; polycarbonate; or polyester; and
a charge-enhancing additive consisting of substituted-benzimidazole compound with
the general structure of Formula 1:
wherein the Y is an NH or S group;
the groups R1, R2, R3, and R4 independently are a hydrogen atom, an alkyl, an aryl, or a substituted alkyl; and
A is a substituted 6-membered aromatic group or a substituted or unsubstituted heterocyclic aromatic 6-membered ring group; and
wherein the electret web has anti-microbial properties.

### Claim 2 (depends on 1)

The electret web of claim 1, wherein the web is a non-woven fibrous web.

### Claim 3 (depends on 1)

The electret web of claim 1, wherein the web is a film.

### Claim 4 (depends on 1)

The electret web of claim 1, wherein Y is NH; and
the A group of Formula 1 is a 6-membered cyclic or heterocyclic aromatic group described by the general structure of Formula 2:
wherein X is: a —C—R9 group, wherein R9 is a hydroxy group; or a nitrogen atom; and
each R5, R6, R7, and R8 independently is a hydrogen atom, an alkyl, an aryl, or a substituted alkyl.

### Claim 5 (depends on 1)

The electret web of claim 1, wherein the charge-enhancing additive is a compound of Formula 1:
wherein Y is an S group; and
the A group is a 6-membered aromatic group described by the general structure of Formula 2:
wherein X is: a —C—R9 group, wherein R9 is a hydroxy group; and
each R5, R6, R7, and R8 independently is a hydrogen atom, an alkyl, an aryl, or a substituted alkyl.

### Claim 6 (depends on 1)

The electret web of claim 1, wherein the charge-enhancing additive is a compound of Formula 1A, Formula 1B, or Formula 1C:

### Claim 7

An electret filter medium consisting of:
a web consisting of:
a thermoplastic resin consisting of polyolefin; polyvinyl chloride; polystyrene; polycarbonate; or polyester; and
a charge-enhancing additive consisting of a substituted-benzimidazole compound with the general structure of Formula 1:
wherein the Y is an NH or S group;
the groups R1, R2, R3, and R4 each independently is a hydrogen atom, an alkyl, an aryl, or a substituted alkyl; and
A is a substituted 6-membered aromatic group or a substituted or unsubstituted heterocyclic aromatic 6-membered ring group; and
wherein the electret filter media has anti-microbial properties.

### Claim 8 (depends on 7)

The electret filter medium of claim 7, wherein the charge-enhancing additive consisting of a compound of Formula 1:
wherein Y is an NH group; and
the A group is a 6-membered aromatic group described by the general structure of Formula 2:
wherein X is: a —C—R9 group, wherein R9 is a hydroxy group;
or a nitrogen atom; and
each R5, R6, R7, and R8 independently is a hydrogen atom, an alkyl, an aryl, or a substituted alkyl.

### Claim 9 (depends on 8)

The electret filter medium of claim 8, wherein X is:
a —C—R9 group, wherein R9 is a hydroxy group; and
each R5, R6, R7, and R8 independently is a hydrogen atom.

### Claim 10 (depends on 8)

The electret filter medium of claim 8, wherein X is:
a nitrogen atom; and
each R5, R6, R7, and R8 independently is a hydrogen atom.

### Claim 11 (depends on 7)

The electret filter medium of claim 7, wherein the charge-enhancing additive is a compound of Formula 1:
wherein Y is an S group; and
the A group is a 6-membered aromatic group described by the general structure of Formula 2:
wherein X is: a —C—R9 group, wherein R9 is a hydroxy group;
and each R5, R6, R7, and R8 independently is a hydrogen atom, an alkyl, an aryl, or a substituted alkyl.

### Claim 12 (depends on 7)

The electret filter medium of claim 7, wherein the charge-enhancing additive is 0.02-5.0% by weight of the web.

### Claim 13 (depends on 7)

The electret filter medium of claim 7, wherein the web contains an electrostatic charge, wherein the charge is imparted through corona treatment, hydrocharging, or a combination thereof.

### Claim 14 (depends on 7)

The electret filter medium of claim 7, wherein the filter medium retains at least 65% filtration performance as measured by Quality Factor after aging for 72 hours at 71° C.

### Claim 15 (depends on 7)

The electret filter medium of claim 7, wherein the charge-enhancing additive is at least one compound of Formula 1A, Formula 1B, or Formula 1C: