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Title:
ELECTRET MATERIALS
Document Type and Number:
WIPO Patent Application WO/2008/122525
Kind Code:
A1
Abstract:
Disclosed are electret materials with outstanding thermal and charge stability. The electret materials comprise a melt blend of a thermoplastic polymer and one or more compounds selected from the aromatic trisamides. The aromatic trisamides are for example of the formula. The melt blends are subjected to an electret treatment, for example a corona treatment. The electret materials are for example nonwoven polyolefin webs and are employed as filter materials, wipes, absorbent materials, filter masks, acoustic materials, printing substrates, measuring devices or contactless switches. The present electret materials may also comprise a further additive selected from the hindered amine light stabilizers and the hydroxyphenylalkylphosphonic esters or monoesters.

Inventors:
CHIN, Hui (145 Route 100, Katonah, NY, 10536, US)
LEGGIO, Andrew, Joseph (41 Lexington Avenue, Franklin Square, NY, 11010, US)
GANDE, Matthew, Edward (26 Bettswood Road, Norwalk, CT, 06851, US)
DEBELLIS, Anthony, David (9 Gooler Court, Stony Point, NY, 10980, US)
SHUM, Sai, Ping (23 Hopper Street, Pleasantville, NY, 10570, US)
KRISTIANSEN, Per, Magnus (Hochstrasse 81, Zürich, CH-8044, CH)
STOLL, Klaus (Am Sonnenrain 18, Binzen, 79589, DE)
Application Number:
EP2008/053707
Publication Date:
October 16, 2008
Filing Date:
March 28, 2008
Export Citation:
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Assignee:
CIBA HOLDING INC. (Klybeckstrasse 141, Basel, CH-4057, CH)
CHIN, Hui (145 Route 100, Katonah, NY, 10536, US)
LEGGIO, Andrew, Joseph (41 Lexington Avenue, Franklin Square, NY, 11010, US)
GANDE, Matthew, Edward (26 Bettswood Road, Norwalk, CT, 06851, US)
DEBELLIS, Anthony, David (9 Gooler Court, Stony Point, NY, 10980, US)
SHUM, Sai, Ping (23 Hopper Street, Pleasantville, NY, 10570, US)
KRISTIANSEN, Per, Magnus (Hochstrasse 81, Zürich, CH-8044, CH)
STOLL, Klaus (Am Sonnenrain 18, Binzen, 79589, DE)
International Classes:
H01G7/02; H01G7/00
Attorney, Agent or Firm:
CIBA HOLDING INC. (Patent Department, Klybeckstrasse 141, Basel, CH-4057, CH)
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Claims:

What is claimed is:

1. An electret material with enhanced thermal and charge stability, which material has been subjected to an electret treatment, comprising a thermoplastic polymer and incorporated therein, an effective stabilizing amount of one or more aromatic trisamide compounds of formula I

wherein

Ri, R 2 , R 3 , R 4 , R 5 and R 6 , independently of one another, are hydrogen, CrC 2 oalkyl, C 2 -C 2o al- kyl substituted by Ci-Ci 0 alkylamino, di(Ci-Ci 0 alkyl)amino, Ci-Ci 0 alkyloxy or hydroxy; C 3 -C 20 - alkenyl, C 5 -Ci 2 cycloalkyl, C 5 -Ci 2 cycloalkyl substituted by 1 , 2 or 3 Ci-Ci θ alkyl; cyclohexyl- methyl; cyclohexylmethyl substituted by 1 , 2 or 3 Ci-Ci θ alkyl; C 5 -C 9 cycloalkenyl, C 5 -C 9 cyclo- alkenyl substituted by 1 , 2 or 3 Ci-Ci θ alkyl; phenyl substituted by 1 , 2 or 3 radicals selected from the group consisting of CrCi O alkyl, CrCi θ alkyloxy, hydroxy, halogen, trihalogenmethyl, trihalogenmethoxy, benzoyl, phenylamino, acylamino and phenylazo; Cr-Cgphenylalkyl, C 7 -C 9 phenylalkyl which is substituted on the phenyl by 1 , 2 or 3 radicals selected from the group consisting of CrCi O alkyl, Ci-Ci θ alkoxy and hydroxy; naphthyl, naphthyl substituted by Ci-Ci θ alkyl; adamantyl, or a 5 to 6 membered heterocyclic group;

or an effective stabilizing amount of one or more aromatic trisamide compounds of the formula Na, Nb or Nc

wherein

Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 independently of one another are C 1 - C 20 alkyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkenyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkyl interrupted by oxygen or sulfur; C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl; (C 3 -C 12 cycloalkyl)- CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; bis[C 3 -C 12 cycloalkyl]-Cr C 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more CrC 20 alkyl; phenyl unsubstituted or substituted by one or more radicals selected from C 1 - C 20 alkyl, CrC 20 alkoxy, CrC 20 alkylamino, di(CrC 20 alkyl)amino, hydroxy and nitro; phenyl-d- C 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 - C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; phenylethenyl unsubstituted or substituted by one or more CrC 20 alkyl; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-CrC 20 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; naphthoxymethyl unsubstituted or substituted by one or more CrC 2 oalkyl; biphenylenyl, flourenyl, anthryl; a 5- to 6-membered heterocyclic radical unsubstituted or substituted by

one or more CrC 2 oalkyl; a CrC 2 ohydrocarbon radical containing one or more halogen; or tri(Ci-Cioalkyl)silyl(Ci-Ci O alkyl); with the proviso that at least one of the radicals Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 2 oalkyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 - alkyl interrupted by oxygen or sulfur; C 3 -Ci 2 cycloalkyl unsubstituted or substituted by one or more Ci-C 20 alkyl; (C 3 -Ci 2 cycloalkyl)-CrCi 0 alkyl unsubstituted or substituted by one or more Ci-C 2 oalkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more Ci-C 20 alkyl; phenyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, CrC 20 alkoxy, Ci-C 20 alkylamino, CIi(C 1 - C 20 alkyl)amino, hydroxy and nitro; phenyl-CrC 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 -C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-d- C 20 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; or tri(C 1 -C 10 alkyl)silyl(C 1 - C 10 alkyl).

2. An electret material according to claim 1 comprising one or more trisamide compounds of formula I.

3. An electret material according to claim 1 comprising one or more trisamide compounds of formula Na, Nb or Nc.

4. An electret material according to claim 1 in which the thermoplastic polymer is polypropylene.

5. An electret material according to claim 1 in which the thermoplastic polymer is a non- woven polypropylene web.

6. An electret material according to claim 1 where in the compounds of formula Na, Nb and Nc, at least one of the radicals R 1 , R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 20 alkyl, or is C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl.

7. An electret material according to claim 1 where the electret treatment is a corona treatment.

8. An electret material according to claim 1 wherein the thermoplastic polymer further has incorporated therein an additive selected from the group consisting of the hindered amine light stabilizers.

9. An electret material according to claim 1 wherein the thermoplastic polymer further has incorporated therein an additive selected from the group consisting of the hydroxyphenylal- kylphosphonic esters or monoesters.

10. An electret material according to claim 1 wherein the aromatic trisamide compounds are present from 0.005 to 0.5% by weight, based on the weight of the thermoplastic polymer.

11. A method for preparing an electret material with enhanced thermal and charge stability, which method comprises melt blending a thermoplastic polymer with an effective stabilizing amount of one or more aromatic trisamide compounds of formula I

Ri

wherein R 1 , R 2 and R 3 , independently of one another, are CrC 2 oalkyl, C 2 -C 2 oalkyl substituted by Ci-Ci 0 alkylamino, di(Ci-Ci 0 alkyl)amino, Ci-Ci 0 alkyloxy or hydroxy; C 3 -C 20 alkenyl, C 5 -Ci 2 - cycloalkyl, C 5 -Ci 2 cycloalkyl substituted by 1 , 2 or 3 Ci-Ci O alkyl; cyclohexylmethyl; cyclohexyl- methyl substituted by 1 , 2 or 3 Ci-Ci O alkyl; C 5 -C 9 cycloalkenyl, C 5 -C 9 cycloalkenyl substituted by 1 , 2 or 3 Ci-Ci O alkyl; phenyl substituted by 1 , 2 or 3 radicals selected from the group consisting of Ci-Cioalkyl, Ci-Ci 0 alkyloxy, hydroxy, halogen, trihalogenmethyl, trihalogenmethoxy, benzoyl, phenylamino, acylamino and phenylazo; C 7 -C 9 phenylalkyl, C 7 - Cgphenylalkyl which is substituted on the phenyl by 1 , 2 or 3 radicals selected from the group consisting of Ci-Ci O alkyl, d-Ci 0 alkoxy and hydroxy; naphthyl, naphthyl substituted by

Ci-Cioalkyl; adamantyl, or a 5 to 6 membered heterocyclic group; or an effective stabilizing amount of one or more aromatic trisamide compounds of the formula Na, Nb or Nc

wherein

Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 , independently of one another, are CrC 20 al- kyl unsubstituted or substituted by one or more hydroxy; C 2 -C 2 oalkenyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkyl interrupted by oxygen or sulfur; C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl; (C 3 -C 12 cycloalkyl)-CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; bis[C 3 -C 12 cycloalkyl]-CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more CrC 20 alkyl; phenyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, CrC 20 alkoxy, CrC 20 alkylamino, di(CrC 20 alkyl)amino, hydroxy and nitro; phenyl-CrC 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 - C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; phenylethenyl unsubstituted or substituted by one or more CrC 20 -alkyl; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl unsubstituted or substituted by one or more CrC 20 alkyl;

naphthyl-CrC 2 oalkyl unsubstituted or substituted by one or more Ci-C 2 oalkyl; naphthoxymethyl unsubstituted or substituted by one or more CrC 2 oalkyl; biphenylenyl, flourenyl, anthryl; a 5- to 6-membered heterocyclic radical unsubstituted or substituted by one or more Ci-C 2 oalkyl; a Ci-C 20 hydrocarbon radical containing one or more halogen; or tri(Ci-Cioalkyl)silyl(Ci-Ci O alkyl); with the proviso that at least one of the radicals Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 20 alkyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 - alkyl interrupted by oxygen or sulfur; C 3 -Ci 2 cycloalkyl unsubstituted or substituted by one or more Ci-C 20 alkyl; (C 3 -Ci 2 cycloalkyl)-Ci-Ci 0 alkyl unsubstituted or substituted by one or more Ci-C 2o alkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more Ci-C 2o alkyl; phenyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, CrC 20 alkoxy, Ci-C 20 alkylamino, CIi(C 1 - C 20 alkyl)amino, hydroxy and nitro; phenyl-CrC 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 -C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; biphenyl-(CrC 1o alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-d- C 2o alkyl unsubstituted or substituted by one or more CrC 20 alkyl; or tri(C 1 -C 1o alkyl)silyl(C 1 - C 1o alkyl); and subjecting the blend to an electret treatment.

12. A method according to claim 1 1 which comprises melt blending the thermoplastic polymer with a further additive selected from the group consisting of the hindered amine light stabilizers.

13. A method according to claim 1 1 which comprises melt blending the thermoplastic polymer with a further additive selected from the group consisting of the hydroxyphenylalkylphosphonic esters or monoesters.

14. A method according to claim 1 1 where the aromatic trisamides are present from 0.005 to 0.5% by weight, based on the weight of the thermoplastic polymer.

Description:

Electret Materials

The present invention is aimed at electret materials having excellent thermal stability and charge stability. The electret materials are for example polyolefin fibers or films and are suitably employed as filter materials, wipes, absorbent materials, filter masks, acoustic materials, printing substrates, measuring devices or contactless switches.

U.S. 5,057,710 teaches electret materials comprising hindered amines, nitrogen containing hindered phenols or metal-containing hindered phenols.

U.S. 5,556,618 discloses antibacterial electret materials.

U.S. 6,123,752 teaches high efficiency filter medium containing a performance enhancing additive.

U.S. 6,743,464 teaches a method of making electrets through vapor condensation.

U.S. 6,969,484 discloses a method of making electret.

US-A-2005/0203226 and WO-A-2004/072168 teach trisamide nucleating agents.

Mohmeyer, et al., in Polymer, 48(2007), 1612-1619, discusses electret materials.

Disclosed is an electret material with enhanced thermal and charge stability, which material has been subjected to an electret treatment, comprising a thermoplastic polymer and incorporated therein, an effective stabilizing amount of one or more aromatic trisamide compounds.

Also disclosed is a method for preparing an electret material with enhanced thermal and charge stability, which method comprises melt blending a thermoplastic polymer with an effective stabilizing amount of one or more aromatic trisamide compounds and subjecting the blend to an electret treatment.

The present invention pertains to an electret material with enhanced thermal and charge stability, which material has been subjected to an electret treatment, comprising a thermoplastic polymer and incorporated therein, an effective stabilizing amount of one or more aromatic trisamide compounds of formula I

wherein

Ri, R 2 , R3, R 4 , R5 and R 6 , independently of one another, are hydrogen, CrC 2 oalkyl, C 2 -C 2o al- kyl substituted by Ci-Ci 0 alkylamino, di(Ci-Ci 0 alkyl)amino, Ci-Ci 0 alkyloxy or hydroxy; C 3 -C 20 - alkenyl, C 5 -Ci 2 cycloalkyl, C 5 -Ci 2 cycloalkyl substituted by 1 , 2 or 3 Ci-Ci θ alkyl; cyclohexyl- methyl; cyclohexylmethyl substituted by 1 , 2 or 3 Ci-Ci θ alkyl; C 5 -C 9 cycloalkenyl, C 5 -C 9 cyclo- alkenyl substituted by 1 , 2 or 3 Ci-Ci θ alkyl; phenyl substituted by 1 , 2 or 3 radicals selected from the group consisting of CrCi O alkyl, CrCi θ alkyloxy, hydroxy, halogen, trihalogenmethyl, trihalogenmethoxy, benzoyl, phenylamino, acylamino and phenylazo; C 7 -C 9 phenylalkyl, Cr-Cgphenylalkyl which is substituted on the phenyl by 1 , 2 or 3 radicals selected from the group consisting of CrCi O alkyl, Ci-Ci θ alkoxy and hydroxy; naphthyl, naphthyl substituted by Ci-Ci θ alkyl; adamantyl, or a 5 to 6 membered heterocyclic group;

or an effective stabilizing amount of one or more aromatic trisamide compounds of the formula Na, Nb or Nc

wherein

Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 independently of one another are C 1 - C 20 alkyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkenyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkyl interrupted by oxygen or sulfur; C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl; (C 3 -C 12 cycloalkyl)- CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; bis[C 3 -C 12 cycloalkyl]-Cr C 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more CrC 20 alkyl; phenyl unsubstituted or substituted by one or more radicals selected from C 1 - C 20 alkyl, CrC 20 alkoxy, CrC 20 alkylamino, di(CrC 20 alkyl)amino, hydroxy and nitro; phenyl-d- C 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 - C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; phenylethenyl unsubstituted or substituted by one or more CrC 20 alkyl; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-CrC 20 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; naphthoxymethyl unsubstituted or substituted by one or more CrC 2 oalkyl; biphenylenyl, flourenyl, anthryl; a 5- to 6-membered heterocyclic radical unsubstituted or substituted by

- A -

one or more CrC 2 oalkyl; a CrC 2 ohydrocarbon radical containing one or more halogen; or tri(Ci-Cioalkyl)silyl(Ci-Ci O alkyl); with the proviso that at least one of the radicals Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 2 oalkyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 - alkyl interrupted by oxygen or sulfur; C 3 -Ci 2 cycloalkyl unsubstituted or substituted by one or more Ci-C 20 alkyl; (C 3 -Ci 2 cycloalkyl)-CrCi 0 alkyl unsubstituted or substituted by one or more Ci-C 2 oalkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more Ci-C 20 alkyl; phenyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, CrC 20 alkoxy, Ci-C 20 alkylamino, CIi(C 1 - C 20 alkyl)amino, hydroxy and nitro; phenyl-CrC 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 -C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-d- C 20 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; or tri(C 1 -C 10 alkyl)silyl(C 1 - C 10 alkyl).

Examples of CrC 20 alkyl are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert- butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1 ,3-dimethylbutyl, n-hexyl, 1-methyl- hexyl, n-heptyl, isoheptyl, 1 ,1 ,3,3-tetramethylbutyl, 1-methylheptyl, 3-methylheptyl, n-octyl, 2-ethylhexyl, 1 ,1 ,3-trimethylhexyl, 1 ,1 ,3,3-tetramethylpentyl, nonyl, decyl, undecyl, 1-methyl- undecyl, dodecyl, 1 ,1 ,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and eicosyl. Preferred examples are butyl, octyl and octadecyl.

Examples of C 2 -C 20 alkyl substituted by CrC 10 alkylamino , di(CrC 10 alkyl)amino, CrC 10 alkyl- oxy or hydroxy are 3-methylaminopropyl, 2-dimethylaminoethyl, 2-diethylaminoethyl, 3-di- methylaminopropyl, 3-diethylaminopropyl, 2-methoxyethyl, 2-ethoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 2-ethoxypropyl, 3-isopropoxypropyl and hydroxyethyl. Preferred examples are 3-dimethylaminopropyl, 3-methoxypropyl and 2-methoxyethyl.

Examples of C 3 -C 2 oalkenyl are allyl, 2-methallyl, butenyl, pentenyl, hexenyl and oleyl. The carbon atom in position 1 is preferably saturated. Preferred examples are allyl and oleyl.

Examples of C 5 -C 12 cycloalkyl are cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and cyclododecyl. Preferred examples are cyclohexyl, cycloheptyl, cyclooctyl and cyclododecyl.

Preferred examples of C 5 -Ci 2 cycloalkyl substituted by 1 , 2 or 3 Ci-Ci O alkyl are 3-methylcyclohexyl and 2,3-dimethylcyclohexyl.

An example of cyclohexylmethyl substituted by 1 , 2 or 3 Ci-Ci O alkyl is 1-cyclohexylethyl.

An example of C 5 -C 9 cycloalkenyl is cyclohexenyl.

An example of C 5 -C 9 cycloalkenyl substituted by 1 , 2 or 3 d-Ci O alkyl is methylcyclohexenyl.

Examples of phenyl substituted by 1 , 2 or 3 radicals selected from the group consisting of Ci-Cioalkyl, Ci-Ci 0 alkyloxy, hydroxy, halogen, trihalogenmethyl, trihalogenmethoxy, benzoyl, phenylamino, acylamino and phenylazo are 4-methylphenyl, 2-ethylphenyl, 4-ethylphenyl, 4- isopropylphenyl, 4-tert-butylphenyl, 4-sec-butylphenyl, 4-isobutylphenyl, 3,5-dimethylphenyl, 3,4-dimethylphenyl, 2,4-dimethylphenyl, 2,6-diethylphenyl, 2-ethyl-6-methylphenyl, 2,6-diiso- propylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-hydroxyphenyl, 4-fluorophenyl, 3,5- difluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 3-chloro-6-methylphenyl, 3,5- di(trifluoromethyl)phenyl, 4-trifluoromethoxyphenyl, 2-benzoylphenyl, 4-phenylaminophenyl, 4-acetamidophenyl and 4-(phenylazo)phenyl. A preferred example is 3,4-dimethylphenyl.

Examples of C 7 -C 9 phenylalkyl are benzyl and 2-phenylethyl. Benzyl is preferred.

Examples of C 7 -C 9 phenylalkyl which is substituted on the phenyl by 1 , 2 or 3 radicals selected from the group consisting of CrCioalkyl, Ci-Cioalkoxy and hydroxy are methylbenzyl, di- methylbenzyl, trimethylbenzyl, tert-butylbenzyl, methoxybenzyl and 3,5-di-tert-butyl-4-hydr- oxybenzyl.

An example of naphthyl substituted by CrCioalkyl is methylnaphthyl.

Examples of a 5 to 6 membered heterocyclic group are 2-picolyl, (2-furyl)methyl, (2-tetrahy- drofuryl)methyl, 2-pyrimidyl, 6-methyl-2-pyridyl, 1 ,2,4-triazol-3-yl and 2-(1-piperazinyl)ethyl.

Examples of CrC 2 oalkyl, e.g. branched C 3 -C 2 oalkyl, unsubstituted or substituted by one or more hydroxy, e.g. 1 , 2 or 3 hydroxy, are ethyl, n-propyl, 1-methylethyl, n-butyl, 2-methylpro- pyl, 1-methylpropyl, tert-butyl, pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1 ,1-

dimethylpropyl, 1 -ethyl propyl, tert-butyl methyl, hexyl, 1-methylpentyl, heptyl, isoheptyl, 1- ethylhexyl, 2-ethylpentyl, 1-propylbutyl, octyl, nonyl, isononyl, neononyl, 2,4,4- trimethylpentyl, undecyl, tridecyl, pentadecyl, heptadecyl, hydroxymethyl and 1 - hydroxyethyl. Branched C 3 -Ci 0 alkyl is particularly preferred. One of the preferred meanings of the radicals Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 10 alkyl with a quaternary C atom in position 1 , in particular -C(CH 3 ) 2 -H or -C(CH 3 ) 2 -(CrC 7 alkyl).

Examples of C 2 -C 20 alkenyl unsubstituted or substituted by one or more hydroxy, e.g. 1 , 2 or 3 hydroxy, are 9-decenyl, 8-heptadecenyl and 1 1-hydroxy-8-heptadecenyl.

Examples of C 2 -C 2 oalkyl interrupted by oxygen are t-butoxymethyl, t-butoxyethyl, tert-butoxy- propyl and t-butoxybutyl.

Examples of C 2 -C 20 alkyl interrupted by sulfur are (H 3 C) 3 C-S-CH 2 -, (H 3 C) 3 C-S-C 2 H 4 -, (H 3 C) 3 C-S-C 3 H 6 - and (H 3 C) 3 C-S-C 4 H 8 -.

Examples of C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl, e.g. 1 , 2, 3 or 4 CrC 4 alkyl, are cyclopropyl, 3-methylcyclopropyl, 2,2,3,3-tetramethylcyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, 1-methylcyclohexyl, 2-methylcyclohexyl, 3-methylcyclo- hexyl, 4-methylcyclohexyl, 4-tert-butylcyclohexyl and cycloheptyl.

Examples of (C 3 -C 12 cycloalkyl)-CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl, e.g. 1 , 2 or 3 CrC 4 alkyl, are cyclopentylmethyl, 2-cyclopentylethyl, cyclohexyl- methyl, 2-cycohexylethyl, 3-cyclohexylpropyl, 4-cyclohexylbutyl and (4-methylcyclohexyl)- methyl.

An example of bis[C 3 -C 12 cycloalkyl]-CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl, e.g. 1 , 2 or 3 CrC 4 alkyl, is dicyclohexylmethyl.

Examples of a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstitu-

ted or substituted by one or more Ci-C 2 oalkyl, e.g. 1 , 2 or 3 CrC 4 alkyl, are

Examples of phenyl unsubstituted or substituted by one or more radicals, e.g. 1 , 2 or 3 radicals, selected from CrC 2 oalkyl, CrC 2 oalkoxy, Ci-C 2 oalkylamino, di(Ci-C 20 alkyl)amino, hydroxy and nitro, preferably Ci-C 4 alkyl, d-C 4 alkoxy, Ci-C 4 alkylamino, di(Ci-C 4 alkyl)amino, hydroxy and nitro, are phenyl, 3-methylphenyl, 3-methoxyphenyl, 4-methylphenyl, 4-ethyl- phenyl, 4-propylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-isopropoxyphenyl, 2,3-di- methoxyphenyl, 2-nitrophenyl, 3-methyl-6-nitrophenyl, 4-dimethylaminophenyl, 2,3-dimethyl- phenyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 3,5-di-tert-butylphenyl, 2,4,6-trimethylphenyl and 3,5-di-tert-butyl-4-hydroxyphenyl.

Examples of phenyl-Ci-C 20 alkyl unsubstituted or substituted by one or more radicals, e.g. 1 , 2 or 3 radicals, selected from CrC 20 alkyl, C 3 -Ci 2 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy, preferably OC 4 alkyl, C 3 -C 6 cycloalkyl, phenyl, d-C 4 alkoxy and hydroxy, are benzyl, α- cyclohexylbenzyl, diphenylmethyl, 1-phenylethyl, α-hydroxybenzyl, 2-phenylethyl, 2-phenyl- propyl, 3-phenylpropyl, 3-methylbenzyl, 3,4-dimethoxybenzyl and 2-(3,4-dimethoxyphenyl)- ethyl.

An example of phenylethenyl unsubstituted or substituted by one or more Ci-C 20 alkyl, e.g. 1 , 2 or 3 Ci-C 4 alkyl, is 2-(4-methylphenyl)ethenyl.

An example of biphenyl-(Ci-Ci O alkyl) unsubstituted or substituted by one or more Ci-C 2 oalkyl, e.g. 1 , 2 or 3 CrC 4 alkyl, is 4-biphenylmethyl.

Examples of naphthyl unsubstituted or substituted by one or more CrC 2 oalkyl, e.g. 1 , 2 or 3 CrC 4 alkyl, are 1 -naphthyl and 2-naphthyl.

Examples of naphthyl-CrC 2 oalkyl unsubstituted or substituted by one or more Ci-C 2 oalkyl, e.g. 1 , 2 or 3 CrC 4 alkyl, are 1-naphthylmethyl and 2-naphthylmethyl.

An example of naphthoxymethyl unsubstituted or substituted by one or more CrC 2 oalkyl, e.g. 1 , 2 or 3 Ci-C 4 alkyl, is 1 -naphthoxymethyl.

An examples of biphenylenyl, flourenyl or anthryl is 2-biphenylenyl, 9-flourenyl, 1-flourenyl or 9-anthryl, respectively.

Examples of a 5- to 6-membered heterocyclic radical unsubstituted or substituted by one or more Ci-C 2 oalkyl, e.g. 1 , 2 or 3 Ci-C 4 alkyl, are 3-pyridinyl, 4-pyridinyl, 2-hydroxypyridin-3-yl, 3-quinolinyl, 4-quinolinyl, 2-furyl, 3-furyl and 1-methyl-2-pyrryl.

Examples of a Ci-C 2 ohydrocarbon radical containing one or more halogen, e.g. 1 , 2, 3, 4, 5, or 6 -F, -Cl or -J, are 1-bromo-2-methylpropyl, dichloromethyl, pentafluoroethyl, 3,5-bis[tri- fluoromethyl]phenyl, 2,3,5,6-tetrafluoro-p-tolyl, 2,3-dichlorophenyl, 3,4-dichlorophenyl and 2,4-bis[trifluoromethyl]phenyl.

Preferably, the electret material comprises one or more trisamide compounds of formula I.

Of interst are electret materials comprising one or more trisamide compounds of formula Na, Nb or Nc.

According to a preferred embodiment, at least one of the radicals R-i, R 2 and R3, or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 20 alkyl, or C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl.

According to a particular preferred embodiment, at least one of the radicals R-i, R 2 and R3, Or Y 1 , Y 2 and Y 3 , Or Z 1 , Z 2 and Z 3 is branched C 3 -C 10 alkyl.

The aromatic trisamide compounds are taught for example in US-A- 2005/0203226 and WO-A-2004/072168.

Examples of compounds of formula (Na) are:

1 ,3,5-tris[cyclohexylcarbonylamino]benzene,

1 ,3,5-tris[2,2-dimethylpropionylamino]benzene,

1 ,3,5-tris[4-methylbenzoylamino]benzene,

1 ,3,5-tris[3,4-dimethylbenzoylamino]benzene,

1 ,3,5-tris[3,5-dimethylbenzoylamino]benzene,

1 ,3,5-tris[cyclopentanecarbonylamino]benzene,

1 ,3,5-tris[1 -adamantanecarbonylamino]benzene,

1 ,3,5-tris[2-methylpropionylamino]benzene,

1 ,3,5-tris[3,3-dimethylbutyrylamino]benzene,

1 ,3,5-tris[2-ethylbutyrylamino]benzene,

1 ,3,5-tris[2,2-dimethylbutyrylamino]benzene,

1 ,3,5-tris[2-cyclohexyl-acetylamino]benzene,

1 ,3,5-tris[3-cyclohexyl-propionylamino]benzene,

1 ,3,5-tris[4-cyclohexyl-butyrylamino]benzene,

1 ,3,5-tris[5-cyclohexyl-valeroylamino]benzene,

1-isobutyrylamino-3,5-bis[pivaloylamino]benzene,

2,2-dimethylbutyrylamino-3,5-bis[pivaloylamino]benzene,

3,3-dimethylbutyrylamino-3,5-bis[pivaloylamino]benzene,

1 ,3-bis[isobutyrylamino]-5-pivaloylaminobenzene,

1 ,3-bis[isobutyrylamino]-5-(2,2-dimethyl-butyryl)aminobenzene ,

1 ,3-bis[isobutyrylamino]-5-(3,3-dimethyl-butyryl)aminobenzene ,

1 ,3-bis[2,2-dimethylbutyrylamino]-5-pivaloylaminobenzene,

1 ,3-bis[2,2-dimethylbutyrylamino]-5-isobutyrylaminobenzene,

1 ,3-bis[2,2-dimethylbutyrylamino]-5-(3,3-dimethylbutyryl)-ami nobenzene,

1 ,3-bis[3,3-dimethylbutyrylamino]-5-pivaloylamino-benzene,

1 ,3-bis[3,3-dimethylbutyrylamino]-5-isobutyryl-aminobenzene,

1 ,3-bis[3,3-dimethylbutyrylamino)-5-(2,2-dimethyl-butyrylamin o)aminobenzene, and

1 ,3,5-tris[3-(trimethylsilyl)propionylamino]benzene.

Further examples of compounds of formula (Na) are:

1 ,3,5-tris[2,2-dimethylvaleroylamino]benzene,

1 ,3,5-tris[3,3-dimethylvaleroylamino]benzene,

1 ,3,5-tris[2,4-dimethylvaleroylamino]benzene,

1 ,3,5-tris[4,4-dimethylvaleroylamino]benzene,

1 ,3,5-tris[4-methylvaleroylamino]benzene,

1 ,3,5-tris[2-methylbutyrylamino]benzene,

1 ,3,5-tris[2-methylvaleroylamino]benzene,

1 ,3,5-tris[3-methylvaleroylamino]benzene,

1 Aδ-trisP^AS-tetramethyl-cyclopropanecarbonylaminolbenzene,

1 ,3,5-tris[cyclopentylacetylamino]benzene,

1 ,3,5-tris[3-cyclopentylpropionylamino]benzene,

1 ,3,5-tris[2-norbornyl-acetylamino]benzene,

1 ,3,5-tris[4-t-butylcyclohexane-1 -carbonylamino]benzene,

1 ,3,5-tris[2-(t-butoxy)-acetylamino]benzene,

1 ,3,5-tris[3-(t-butoxy)-propionylamino]benzene,

1 ,3,5-tris[4-(t-butoxy)-butyrylamino]benzene,

1 ,3,5-tris[5-t-butoxy-valeroylamino]benzene, l Aδ-tristcyclopropanecarbonylaminoJbenzene,

1 ,3,5-tris[2-methylcyclopropane-1 -carbonylamino]benzene,

1 ,3,5-tris[3-noradamantane-1 -carbonylamino]benzene,

1 ,3,5-tris[biphenyl-4-acetylamino]benzene,

1 ,3,5-tris[2-naphthyl-acetylamino]benzene,

1 ,3,5-tris[3-methylphenyl-acetylamino]benzene,

1 ,3,5-tris[(3,4-dimethoxyphenyl)-acetylamino]benzene,

1 ,3,5-tris[(3-trimethylsilyl-propionylamino]benzene, and

1 ,3,5-tris[(4-trimethylsilyl-butyrylamino]benzene.

Examples of compounds of formula (lib) are: N-t-butyl-3,5-bis-(3-methylbutyrylamino)-benzamide, N-t-butyl-3,5-bis-(pivaloylamino)-benzamide, N-t-octyl-3,5-bis-(pivaloylamino)-benzamide,

N-(1 ,1-dimethyl-propyl)-3,5-bis-(pivaloylamino)-benzamide,

N-(t-octyl)-3,5-bis-(isobutyrylamino)-benzamide,

N-(t-butyl)-3,5-bis-(pivaloylamino)-benzamide,

N-(2,3-dimethyl-cyclohexyl)-3,5-bis-(pivaloylamino)-benza mide,

N-t-butyl-3,5-bis-(cyclopentanecarbonylamino)-benzamide,

N-(3-methylbutyl)-3,5-bis-(3-methylbutyrylamino)-benzamid e,

N-(3-methylbutyl)-3,5-bis-(pivaloylamino)-benzamide,

N-(3-methylbutyl)-3,5-bis-(4-methylpentanoylamino)-benzam ide,

N-(3-methylbutyl)-3,5-bis-(cyclopentanecarbonylamino)-ben zamide,

N-(3-methylbutyl)-3,5-bis-(cyclohexanecarbonylamino)-benz amide,

N-cyclopentyl-3,5-bis-(3-methylbutyrylamino)-benzamide,

N-cyclopentyl-3,5-bis-(pivaloylamino)-benzamide,

N-cyclopentyl-3,5-bis-(4-methylpentanoylamino)-benzamide,

N-cyclopentyl-3,5-bis-(cyclopentanecarbonylamino)-benzami de,

N-cyclopentyl-3,5-bis-(cyclohexanecarbonylamino)-benzamid e,

N-cyclohexyl-3,5-bis-(3-methylbutyrylamino)-benzamide,

N-cyclohexyl-3,5-bis-(pivaloylamino)-benzamide,

N-cyclohexyl-3,5-bis-(4-methylpentanoylamino)-benzamide,

N-cyclohexyl-3,5-bis-(cyclopentanecarbonylamino)-benzamid e,

N-cyclohexyl-3,5-bis-(cyclohexanecarbonylamino)-benzamide ,

N-isopropyl-3,5-bis-(pivaloylamino)-benzamide,

N-isopropyl-3,5-bis-(isobutyrylamino)-benzamide,

N-t-butyl-3,5-bis-(2,2-dimethylbutyrylamino)-benzamide, and

N-t-octyl-3,5-bis-(2,2-dimethylbutyrylamino)-benzamide.

Examples of compounds of formula (lie) are: 5-pivaloylamino-isophthalic acid N,N'-di-t-butyldiamide, 5-pivaloylamino-isophthalic acid N,N'-di-t-octyldiamide, 5-(2,2-dimethylbutyrylamino)-isophthalic acid N,N'-di-t-butyldiamide, 5-(2,2-dimethylbutyrylamino)-isophthalic acid N,N'-di-t-octyldiamide, 5-(3-methylbutyrylamino)-isophthalic acid N,N'-di-cyclohexyldiamide, 5-(pivaloylamino)-isophthalic acid N,N'-di-cyclohexyldiamide, 5-(cyclopentanecarbonylamino)-isophthalic acid N,N'-di-cyclohexyldiamide, 5-(cyclohexylcarbonylamino)-isophthalic acid N,N'-di-cyclohexyldiamide,

5-(cyclopentanecarbonylamino)-isophthalic acid N,N'-bis-(2-methylcyclohexyl)diamide,

5-(cyclohexanecarbonylamino)-isophthalic acid N,N'-bis-(2-methylcyclohexyl)diamide,

5-((1-methylcyclohexanecarbonyl)amino)-isophthalic acid N,N'-bis-(2-methylcyclohexyl)di- amide, and

5-((2-methylcyclohexanecarbonyl)amino)-isophthalic acid N,N'-bis-(2-methylcyclohexyl)di- amide.

The thermoplastic polymer is a non-conductive polymer that has the capability of possessing a non-transitory or long-lived trapped charge. The polymer is for example a polyolefin, a halogenated vinyl polymer (e.g. polyvinyl chloride), polystyrene, polycarbonate, a polyester (e.g. polyethylene terephthalate), a polyamide or a fluoropolymer (e.g. polytetrafluoroethy- lene).

The thermoplastic polymers are for example propylene homopolymers, propylene copolymers and polypropylene blends. Propylene copolymers may contain various proportions up to 90%, preferably up to 50%, of comonomers. Examples of comonomers are: olefins such as 1 -olefins, e.g. ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene or 1-octene, isobuty- lene, cycloolefins, e.g. cyclopentene, cyclohexene, norbornene or ethylidenenorborne, di- enes such as butadiene, isoprene, 1 ,4-hexadiene, cyclopentadiene, dicyclopentadiene or norbornadiene; also acrylic acid derivatives and unsaturated carboxylic anhydrides such as maleic anhydride.

Polypropylene blends which can be used are mixtures of polypropylene with polyolefins. Examples are blends of polypropylene with polyethylene selected from the group consisting of high density polyethylene (HDPE), high molecular weight high density polyethylene (HMW HDPE), ultra high molecular weight high density polyethylene (UHMW HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE) and ethylene-propylene-diene terpolymers (EPDM) containing small proportions of diene.

The polymer is especially a polyolefin, for example polypropylene, poly(4-methyl-1-pentene) or linear low density polyethylene, or blends or copolymers thereof. The polymer may be a blend of a polyolefin and a polymer that contains polar groups, for example a polyester or a polyamide.

Polypropylene includes for instance reactor (such as metallocene) and visbroken (e.g. peroxides, hydroxylamine esters, thermally broken, etc.) grades.

Preferably, the thermoplastic polymer is polypropylene.

The electret material comprising the thermoplastic material is in the form of a nonwoven web, preferably a nonwoven polypropylene web, a film, or a woven fabric. The electret material is in particular a nonwoven fibrous web.

The thermoplastic polymer may also be for example polyurethane or a polyester such as polylactic acid. The polyurethane may for example be in the form of a foam.

In addition to thermoplastic fibers, the electret material may be a natural fiber such as cotton.

The electret treatment may be any known treatment. Electret treatments are taught for example in U.S. 5,057,710; U.S. 5,556,618; U.S. 6,123,752; U.S. 6,743,464; U.S. 6,969,484; U.S. 6,284,339; U.S. 5,256,176 and U.S. 6,926,961. The electret treatment is for example hydro-charging, tribo-electric charging or corona treatment. The electret treatment is especially a corona treatment.

An electret material according to this invention is a thermoplastic material that has been subjected to an electret treatment.

The addition of the aromatic trisamides to the thermoplastic polymer can be carried out in all customary mixing machines in which the polymer is melted and mixed with the additives.

Suitable machines are known to those skilled in the art. They are predominantly mixers, kneaders and extruders.

The process is preferably carried out in an extruder by introducing the additives during processing.

Particularly preferred processing machines are single-screw extruders, contrarotating and corotating twin-screw extruders, planetary-gear extruders, ring extruders or cokneaders. It is also possible to use processing machines provided with at least one gas removal compartment to which a vacuum can be applied.

Suitable extruders and kneaders are described, for example, in Handbuch der Kunststoffex- trusion, Vol. 1 Grundlagen, Editors F. Hensen, W. Knappe, H. Potente, 1989, pp. 3-7, ISBN:3-446-14339-4 (Vol. 2 Extrusionsanlagen 1986, ISBN 3-446-14329-7). For example, the screw length is 1 - 60 screw diameters, preferably 35-48 screw diameters. The rotational speed of the screw is preferably 10 - 600 rotations per minute (rpm), very particularly preferably 25 - 300 rpm.

The maximum throughput is dependent on the screw diameter, the rotational speed and the driving force. The process of the present invention can also be carried out at a level lower than maximum throughput by varying the parameters mentioned or employing weighing machines delivering dosage amounts.

If a plurality of components are added, these can be premixed or added individually.

The polymers need to be subjected to an elevated temperature for a sufficient period of time during incorporation of additives. The temperature is generally above the softening point of the polymers.

In a preferred embodiment of the processes of the present invention, a temperature range lower than 280 0 C, particularly from about 160 0 C to 280 0 C is employed. In a particularly preferred process variant, the temperature range from about 200°C to 270°C is employed.

In the processes and compositions of the present invention the above-described aromatic trisamide compounds are present in concentrations, based on the amount of the polymer, of from 0.001 to 1.0% by weight. For instance, the trisamides are present from 0.005 to 0.5% by weight, from 0.01 to 0.1 % by weight, from 0.01 to 0.09% by weight, based on the weight of the polymer. The aromatic trisamides can be added as individual compounds or as mixtures to the polymer.

lncorporation of additives into the polymers can be carried out, for example, by mixing the above-described aromatic trisamides or mixtures thereof and, if desired, further additives into the polymers using the methods customary in process technology.

The aromatic trisamides can also be added to the polymers in the form of a masterbatch in which these compounds are present, for example, in a concentration of from about 1 to 25% by weight. The present invention therefore further provides a concentrate in which the compounds of the invention are present in a concentration of 1 - 25% by weight and which can be added to the thermoplastic polymer.

Another aspect of this invention is that instead of melt blending, the present trisamides may be topically applied to the electret material.

For example in the case where the electret material is cotton the present trisamides may be topically applied.

Another aspect of this invention is the co-use of certain other additives along with the present aromatic trisamides. These certain other additives are incorporated in the same manner as the trisamides.

When employed without certain co-additives, the trisamides

are excluded from the present invention.

For instance, the class of stabilizers of the hindered amine light stabilizers (HALS) are advantageously also employed in the present compositions and processes.

The present sterically hindered amine stabilizers contain at least one moiety of formula

where Gi, G 2 , G 3 and G 4 are independently alkyl of 1 to 8 carbon atoms or Gi and G 2 or G 3 and G 4 together are pentamethylene and G 5 is hydrogen or alkyl of 1 to 8 carbon atoms.

The hindered amines are disclosed for example in U.S. 5,004,770; U. S 5,204,473; U.S. 5,096,950; U.S. 5,300,544; U.S 5,1 12,890; U.S. 5,124,378; U.S. 5,145,893; U.S. 5,216,156; U.S. 5,844,026; U.S. 5,980,783; U.S. 6,046,304; U.S. 6,1 17,995; U.S. 6,271 ,377; U.S. 6,297,299; U.S. 6,392,041 ; U.S. 6,376,584; U.S. 6,472,456 and U.S. 7,030,196.

U.S. 6,271 ,377; U.S. 6,392,041 and U.S. 6,376,584, cited above disclose hindered hydroxy- alkoxyamine stabilizers.

Suitable hindered amines include for example:

1 ) 1 -cyclohexyloxy^^^θ-tetramethyM-octadecylaminopiperidine,

2) bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate,

3) bis(1-acetoxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate,

4) bis(1 ,2,2,6,6-pentamethyl-4-yl) sebacate,

5) bis(1 -cyclohexyloxy^^θ.θ-tetramethylpiperidin^-yl) sebacate,

6) bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate;

7) bis(1-acyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate,

8) bis(1 ,2,2,6,6-pentamethyl-4-piperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate,

9) 2,4-bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)b utylamino]-6-(2-hydroxyethyl- amino-s-triazine,

10) bis(1 -cyclohexyloxy^^θ.θ-tetramethylpiperidin^-yl) adipate,

1 1 ) 2,4-bis[(1 -cyclohexyloxy^^^.θ-piperidin^-yObutylaminol-θ-chloro-s-tr iazine,

12) 1 -(2-hydroxy-2-methylpropoxy)-4-hydroxy-2,2,6,6-tetramethylpi peridine,

13) 1 -(2-hydroxy-2-methylpropoxy)-4-oxo-2,2,6,6-tetramethylpiperi dine,

14) 1 -(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetra methylpiperidine,

15) bis(1 -(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4- yl) sebacate,

16) bis(1 -(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4- yl) adipate,

17) 2,4-bis{N-[1 -(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4- yl]-N-butyl- amino}-6-(2-hydroxyethylamino)-s-triazine,

18) 4-benzoyl-2,2,6,6-tetramethylpiperidine,

19) di-(1 ,2,2,6,6-pentamethylpiperidin-4-yl) p-methoxybenzylidenemalonate,

20) 4-stearyloxy-2,2,6,6-tetramethylpiperidine,

21 ) bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate,

22) 1 ,2,2,6,6-pentamethyl-4-aminopiperidine,

23) 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4, 5]decane,

24) tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate,

25) tris(2-hydroxy-3-(amino-(2,2,6,6-tetramethylpiperidin-4-yl)p ropyl) nitrilotriacetate,

26) tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1 ,2,3,4-butane-tetracarboxylate,

27) tetrakis(1 ,2,2,6,6-pentamethyl-4-piperidyl)-1 ,2,3,4-butane-tetracarboxylate,

28) 1 ,1 '-(1 ,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone),

29) 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decan-2,4-dione,

30) δ-acetyl-S-dodecyl^J^.θ-tetramethyl-i ^.δ-triazaspiro^.δldecane^^-dione,

31 ) 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5- dione,

32) 3-dodecyl-1 -(1 ,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione,

33) N,N'-bis-formyl-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hex amethylenediamine,

34) the reaction product of 2, 4-bis[(1-cyclohexyloxy-2, 2,6, 6-piperidin-4-yl)butylamino]-6- chloro-s-triazine with N,N'-bis(3-aminopropyl)ethylenediamine),

35) the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid,

36) linear or cyclic condensates of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene- diamine and 4-tert-octylamino-2,6-dichloro-1 ,3,5-triazine,

37) linear or cyclic condensates of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene- diamine and 4-cyclohexylamino-2,6-dichloro-1 ,3,5-triazine,

38) linear or cyclic condensates of N,N'-bis-(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylene- diamine and 4-morpholino-2,6-dichloro-1 ,3,5-triazine,

39) linear or cyclic condensates of N,N'-bis-(1 , 2,2,6, 6-pentamethyl-4-piperidyl)-hexamethy- lenediamine and 4-morpholino-2,6-dichloro-1 ,3,5-triazine,

40) the condensate of 2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl )-1 ,3,5- triazine and 1 ,2-bis(3-aminopropylamino)ethane,

41 ) the condensate of 2-chloro-4,6-di-(4-n-butylamino-1 , 2,2,6, 6-pentamethylpiperidyl)- 1 ,3,5-triazine and 1 ,2-bis-(3-aminopropylamino)ethane,

42) a reaction product of 7,7,9, 9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro [4,5]decane and epichlorohydrin,

43) poly[methyl-(3-oxy-(2,2,6,6-tetramethylpiperidin-4-yl)propyl )] siloxane, CAS#182635-99-0,

44) reaction product of maleic acid anhydride-Ci 8 -C 22 -a-olefin-copolymer with 2,2,6,6-tetra- methyl-4-aminopiperidine,

45) the oligomeric compound which is the condensation product of 4,4'-hexamethylene-bis- (amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(2,2,6,6-tetramethylpiperidin-4-yl)- butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine,

46) the oligomeric compound which is the condensation product of 4,4'-hexamethylene-bis- (amino-1 ,2,2,6,6-pentaamethylpiperidine) and 2,4-dichloro-6-[(1 , 2,2,6, 6-pentamethylpiperi- din-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine,

47) the oligomeric compound which is the condensation product of 4,4'-hexamethylene- bis(amino-1 -propoxy-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1 -propoxy-2, 2,6,6- tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutyl- amino)-s-triazine,

48) the oligomeric compound which is the condensation product of 4,4'-hexamethylene- bis(amino-1 -acyloxy-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6-[(1 -acyloxy-2, 2,6,6- tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutyl- amino)-s-triazine and

49) product obtained by reacting a product, obtained by reacting 1 ,2-bis(3-aminopropyl- amino)ethane with cyanuric chloride, with (2,2,6,6-tetramethylpiperidin-4-yl)butylamine.

Also included are the sterically hindered N-H, N-methyl, N-methoxy, N-propoxy, N-octyloxy, N-cyclohexyloxy, N-(2-hydroxy-2-methylpropoxy) and N-acyl analogues of any of the above mentioned compounds. For example, replacing an N-H hindered amine with an N-methyl hindered amine would be employing the N-methyl analogue in place of the N-H.

The class of additives known as the hydroxyphenylalkylphosphonic esters or monoesters are also advantegously employed in the processes and compositions of this invention. The hydroxyphenylalkylphosphonic esters or monoesters are disclosed for example in U.S. published app. No. 2004/0106767. The hydroxyphenylalkylphosphonic esters or monoesters are of the formula

wherein

R 6 is isopropyl, tert-butyl, cyclohexyl or cyclohexyl which is substituted by 1 -3 Ci-C 4 alkyl groups,

R 7 is hydrogen, d-C 4 alkyl, cyclohexyl or cyclohexyl which is substituted by 1-3 Ci-C 4 alkyl groups,

R 8 is CrC 2 oalkyl, unsubstituted or Ci-C 4 alkyl-substituted phenyl or naphthyl,

R 9 is hydrogen, CrC 2 oalkyl, unsubstituted or Ci-C 4 alkyl-substituted phenyl or naphthyl; or is

M r+

M r+ is an r-valent metal cation, p is 1 , 2, 3, 4, 5 or 6, and r is 1 , 2 or 3.

For example, the present hydroxyphenylalkylphosphonic ester or monoester is a compound of the formula P1 or P2

(P1 ) (P2).

The further additives of the hindered amine light stabilizers and the hydroxyphenylalkylphos- phonic esters or monoesters are employed at levels, based on the weight of the polymer, of from 0.001 to 5.0% by weight, in particular from 0.01 to 2.0% by weight and particularly preferably from 0.02 to 1.0% by weight.

The invention relates also to a method for preparing an electret material with enhanced thermal and charge stability, which method comprises melt blending a thermoplastic polymer with an effective stabilizing amount of one or more aromatic trisamide compounds of formula I

? 1

wherein R 1 , R 2 and R 3 , independently of one another, are CrC 2 oalkyl, C 2 -C 2 oalkyl substituted by Ci-Ci 0 alkylamino, di(Ci-Ci 0 alkyl)amino, Ci-Ci 0 alkyloxy or hydroxy; C 3 -C 20 alkenyl, C 5 -Ci 2 - cycloalkyl, C 5 -Ci 2 cycloalkyl substituted by 1 , 2 or 3 Ci-Ci O alkyl; cyclohexylmethyl; cyclohexyl- methyl substituted by 1 , 2 or 3 Ci-Ci O alkyl; C 5 -C 9 cycloalkenyl, C 5 -C 9 cycloalkenyl substituted by 1 , 2 or 3 Ci-Ci O alkyl; phenyl substituted by 1 , 2 or 3 radicals selected from the group consisting of Ci-Cioalkyl, Ci-Ci 0 alkyloxy, hydroxy, halogen, trihalogenmethyl, trihalogenmethoxy, benzoyl, phenylamino, acylamino and phenylazo; C 7 -C 9 phenylalkyl, C 7 - Cgphenylalkyl which is substituted on the phenyl by 1 , 2 or 3 radicals selected from the group consisting of Ci-Ci O alkyl, d-Ci 0 alkoxy and hydroxy; naphthyl, naphthyl substituted by C-i-C-ioalkyl; adamantyl, or a 5 to 6 membered heterocyclic group; or an effective stabilizing amount of one or more aromatic trisamide compounds of the formula Na, Nb or Nc

wherein

Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 , independently of one another, are CrC 20 al- kyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkenyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 alkyl interrupted by oxygen or sulfur; C 3 -C 12 cycloalkyl unsubstituted or substituted by one or more CrC 20 alkyl; (C 3 -C 12 cycloalkyl)-CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; bis[C 3 -C 12 cycloalkyl]-CrC 10 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more C-ι-C 2 oalkyl; phenyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, CrC 20 alkoxy, CrC 20 alkylamino, di(CrC 20 alkyl)amino, hydroxy and nitro; phenyl-CrC 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 - C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; phenylethenyl unsubstituted or substituted by one or more CrC 20 -alkyl; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-CrC 20 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; naphthoxymethyl unsubstituted or substituted by one or more CrC 2 oalkyl; biphenylenyl, flourenyl, anthryl; a 5- to 6-membered heterocyclic radical unsubstituted or substituted by

one or more CrC 2 oalkyl; a CrC 2 ohydrocarbon radical containing one or more halogen; or tri(Ci-Cioalkyl)silyl(Ci-Ci O alkyl); with the proviso that at least one of the radicals Ri, R 2 and R 3 , or Y 1 , Y 2 and Y 3 , or Z 1 , Z 2 and Z 3 is branched C 3 -C 2 oalkyl unsubstituted or substituted by one or more hydroxy; C 2 -C 20 - alkyl interrupted by oxygen or sulfur; C 3 -Ci 2 cycloalkyl unsubstituted or substituted by one or more Ci-C 20 alkyl; (C 3 -Ci 2 cycloalkyl)-CrCi 0 alkyl unsubstituted or substituted by one or more Ci-C 2 oalkyl; a bicyclic or tricyclic hydrocarbon radical with 5 to 20 carbon atoms unsubstituted or substituted by one or more Ci-C 20 alkyl; phenyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, CrC 20 alkoxy, Ci-C 20 alkylamino, CIi(C 1 - C 20 alkyl)amino, hydroxy and nitro; phenyl-CrC 20 alkyl unsubstituted or substituted by one or more radicals selected from CrC 20 alkyl, C 3 -C 12 cycloalkyl, phenyl, CrC 20 alkoxy and hydroxy; biphenyl-(CrC 10 alkyl) unsubstituted or substituted by one or more CrC 20 alkyl; naphthyl-d- C 20 alkyl unsubstituted or substituted by one or more CrC 20 alkyl; or tri(C 1 -C 10 alkyl)silyl(C 1 - C 10 alkyl); and subjecting the blend to an electret treatment.

The preferences for the method for preparing an electret material are the same as those disclosed above for the electret material itself.

Preferably, the method for preparing an electret material comprises melt blending the thermoplastic polymer with a further additive selected from the group consisting of the hindered amine light stabilizers.

Of special interest is a method for preparing an electret material which comprises melt blending the thermoplastic polymer with a further additive selected from the group consisting of the hydroxyphenylalkylphosphonic esters or monoesters.

Of interest is also a method for preparing an electret material where the aromatic trisamides are present from 0.005 to 0.5% by weight, based on the weight of the thermoplastic polymer.

The following Examples further illustrate the invention. All percentages are in weight percent unless otherwise indicated.

Example 1 :

Polypropylene with MFI index of 1 ,100 is tumble mixed to contain 5.0% total weight of a sterically hindered amine (HALS), 2.0% total weight of a sterically hindered hydroxyphenylalkylphosphonic monoester (HPPME), 0.25% total weight aromatic trisamide (TA1 ) - (TA14).

These mixes are individually compounded using a Leistritz 27 mm twin screw extruder. The melt is cooled in a water trough and the strand is converted into pellets via a Conair-Jetro Model 304 pelletizer. The pellets collected are considered the masterbatches.

The same polypropylene is tumble mixed with the appropriate amounts of masterbatch for each of the evaluations. The tumble mixing is via a Marion Mixer SPS 1224 which is a paddle type slow RPM mixer. These are considered the final mixes.

Final mixes at 45Kg each are converted into melt blown non woven textiles using a 500mm Reifenhauser Meltblowing Pilot Line. Also a 1 ,50Og portion of each final mix is processed on a 6-inch Meltblowing Pilot Line.

The polypropylene webs are then treated by corona discharge. The samples are tested using TSI Filter Tester (Model 8130) which employs challenges of sodium chloride aerosol at 32 liters per minute using a test area of 100 cm 2 . The results are summarized in the tables below.

Table 1 : 6-inch Meltblowing Pilot Line

Table 2: 6-inch Meltblowing Pilot Line

Table 3: 500mm Reifenhauser Meltblowing Pilot Line

Table 4: 500mm Reifenhauser Meltblowing Pilot Line

Table 5: PP 6-inch Meltblowing Pilot Line

It can be seen that the present aromatic trisamides provide polypropylene with excellent thermal and charge stability. The trisamides are present at very low levels.

sterically hindered hydroxyphenylalkylphosphonic monoester (HPPME)

sterically hindered amine (HALS)

aromatic trisamide (T A1 )

aromatic trisamide (T A2)

aromatic trisamide (T A3)

aromatic trisamide (T A4)

aromatic trisamide (T A5)

aromatic trisamide (T A6)

aromatic trisamide (T A7)

aromatic trisamide (T A8)

aromatic trisamide (T A9)

aromatic trisamide (TA10)

aromatic trisamide (TA11 )

aromatic trisamide (TA12)

aromatic trisamide (TA13)

aromatic trisamide (TA14)