Electret webs with charge-enhancing additives

Patent metadata

Field	Value
Publication number	US-10240269-B2
Application number	US-201515320176-A
Country	US
Kind code	B2
Filing date	Jun 9, 2015
Priority date	Jun 23, 2014
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

Electret webs include a thermoplastic resin and a charge-enhancing additive. The charge-enhancing additive is a fused aromatic thiourea, a fused aromatic urea compound, or a combination thereof. The change-enhancing additive may also include a hindered amine light stabilizer compound. The electret webs may be a non-woven fibrous web or a film. The electret webs are suitable for use as filter media.

First claim

What is claimed is:

1. An electret web comprising:
a thermoplastic resin; and
a charge-enhancing additive comprising a fused aromatic thiourea, a fused aromatic urea compound, or a combination thereof.

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

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

4. The electret web of claim 1 , wherein the fused aromatic thiourea compound comprises a compound with the structure (a):

wherein X═S, the groups R1 and R2 independently comprise a hydrogen atom, or an alkyl group;
the groups R3, R4, R5, and R6 independently comprise a hydrogen atom, an alkyl, an aryl, a heteroalkyl, a substituted alkyl, substituted aryl, or alkoxy.

5. The electret web of claim 4 , wherein the groups R1 and R2 comprise hydrogen atoms;
three of the groups R3, R4, R5, and R6 comprise a hydrogen atoms, and one of the groups R3, R4, R5, and R6 comprises an alkyl group.

6. The electret web of claim 1 , wherein the fused aromatic urea compound comprises a compound with the structure (b):

wherein X═O, the groups R1 and R2 independently comprise a hydrogen atom, or an alkyl group;
the groups R3, R4, R5, and R6 independently comprise a hydrogen atom, an alkyl, an aryl, a heteroalkyl, a substituted alkyl, substituted aryl, or alkoxy.

7. The electret web of claim 6 , wherein the groups R1 and R2 comprise hydrogen atoms;
three of the groups R3, R4, R5, and R6 comprise a hydrogen atoms, and one of the groups R3, R4, R5, and R6 comprises an alkyl group.

8. The electret web of claim 1 , wherein the charge-enhancing additive further comprises at least one hindered amine light stabilizer compound.

9. The electret web of claim 1 , wherein the thermoplastic resin comprises:
polyolefin; polyvinyl chloride; polystyrene; polycarbonate; or polyester.

10. The electret web of claim 1 , wherein the charge-enhancing additive or additives comprise 0.02-5.0% by weight of the web.

11. The electret web of claim 1 , wherein the web contains an electrostatic charge, wherein the charge is imparted through corona treatment, hydrocharging, or a combination thereof.

12. The electret web of claim 1 , wherein the web further comprises at least one additional additive selected from pigments, light stabilizers, primary and secondary antioxidants, metal deactivators, nucleating agents, hindered amines, hindered phenols, fatty acid metal salts, triester phosphites, phosphorous-containing compounds, sulfur-containing compounds, fluorine-containing compounds and combinations thereof.

13. An electret filter medium comprising:
a web comprising:
a thermoplastic resin; and
a charge-enhancing additive comprising a fused aromatic thiourea, a fused aromatic urea compound, or a combination thereof.

14. The electret filter medium of claim 13 , wherein the fused aromatic thiourea compound comprises a compound with the structure (a):

wherein X═S, the groups R1 and R2 independently comprise a hydrogen atom, or an alkyl group;
the groups R3, R4, R5, and R6 independently comprise a hydrogen atom, an alkyl, an aryl, a heteroalkyl, a substituted alkyl, substituted aryl, or alkoxy.

15. The electret filter medium of claim 14 , wherein the groups R1 and R2 comprise hydrogen atoms;
three of the groups R3, R4, R5, and R6 comprise a hydrogen atoms, and one of the groups R3, R4, R5, and R6 comprises an alkyl group.

16. The electret filter medium of claim 13 , wherein the fused aromatic urea compound comprises a compound with the structure (b):

wherein X═O, the groups R1 and R2 independently comprise a hydrogen atom, or an alkyl group;
the groups R3, R4, R5, and R6 independently comprise a hydrogen atom, an alkyl, an aryl, a heteroalkyl, a substituted alkyl, substituted aryl, or alkoxy.

17. The electret filter medium of claim 16 , wherein the groups R1 and R2 comprise hydrogen atoms;
three of the groups R3, R4, R5, and R6 comprise a hydrogen atoms, and one of the groups R3, R4, R5, and R6 comprises an alkyl group.

18. The electret filter medium of claim 13 , wherein the charge-enhancing additive further comprises at least one hindered amine light stabilizer compound.

19. The electret filter medium of claim 13 , wherein the thermoplastic resin comprises:
polyolefin; polyvinyl chloride; polystyrene; polycarbonate; or polyester.

20. The electret filter medium of claim 13 , wherein the charge-enhancing additive or additives comprise 0.02-5.0% by weight of the web.

21. The electret filter medium of claim 1 , wherein the web contains an electrostatic charge, wherein the charge is imparted through corona treatment, hydrocharging, or a combination thereof.

22. The electret filter medium of claim 13 , wherein the web further comprises at least one additional additive selected from pigments, light stabilizers, primary and secondary antioxidants, metal deactivators, nucleating agents, hindered amines, hindered phenols, fatty acid metal salts, triester phosphites, phosphorous-containing compounds, sulfur-containing compounds, fluorine-containing compounds and combinations thereof.

Assignees

• 3M Innovative Properties Co

Inventors

• Schultz Nathan E
• Li Fuming B
• Sebastian John M

Classifications

• D06M10/025

  Corona discharge or low temperature plasma · CPC title

• B01D39/1623 Primary

  of synthetic origin · CPC title

• D04H1/56 Primary

  in association with fibre formation, e.g. immediately following extrusion of staple fibres · CPC title

• B01D2239/0622

  Melt-blown · CPC title

• B01D46/0032

  using electrostatic forces to remove particles, e.g. electret filters · CPC title