Vinylic hindered amine light stabilizers

Details Vinylic hindered amine light stabilizers Vinylic hindered amine light stabilizers

2001-02-22

2004-05-18

Morris, Patricia L. (Department: 1625)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S216000, C546S221000, C546S224000, C546S226000, C546S244000, C546S247000, C546S248000

Reexamination Certificate

active

06737528

ABSTRACT:

FIELD OF INVENTION
This invention relates to vinylic-derivatives of Hindered Amine Light Stabilizer (HALS) having general formula (I):
wherein:
R
1
is C
1
to C
8
alkyl, alkoxy, alkyl phenyl, hydroxy alkyl (all linear and branched), allyl, acyl, cycloalkyl (cyclopentyl, cyclohexyl or cumyl: linear and branched); R
2
is hydrogen and methyl, R
3
is vinyl, C
1
-C
4
vinyl alkyl [H
2
C═C(R
4
)C
1
-C
4
] R
4
is H, C
1
-C
4
alkyl and alkyl phenyl and R
5
is H, C
1
-C
4
alkyl, X is O, NH, C
1
-C
8
alkyloxy and alkylamino: (linear or branched) and the process for the synthesis thereof.
BACKGROUND OF INVENTION
Monomeric hindered amine light stabilizers are gaining much more importance to stabilize the polyolefins and dicne elastomers. Natural and synthetic polymers in common use are susceptible to photo-oxidative degradation upon exposure to natural and artificial weathering. The deterioration of these polymeric materials is mainly due to the UV portion of sunlight reaching the earth surface. The net result of degradation is the loss in the Molecular weight and macroscopic physical properties. Polyolefins and unsaturated synthetic elastomers, being highly sensitive to oxidation, require the addition of stabilizers to provide protection during processing, storage and end-use. The low Molecular weight stabilizers are easily lost from the polymer through evaporation, migration and extraction but, the compatible and mobile stabilizers usually give the best protection. In older to avoid this loss polymer-bound and polymeric stabilizes have been devised. Moreover, since the degradation of a polymer commences from the surface and slowly proceeds into the matrix of the polymeric substrate, the stabilizers are therefore expected to be most potent if they are concentrated at the surface. Therefore, they should be anchored covalently to the polymer surface. Monomeric light stabilizers thus prove to be the best choice to attain the desired photostability.
A discrete literature on the synthesis of the vinylic derivatives of HALS is available; some of these methods are quite trivial and employ complex routes using expensive reagents. Following patents and literature: DE 2950067 (January 1981); DE 2642446 (March 1978),; F. E. Karrer,
Markromol. Chem
. 181, 595 (German) 1980, N. S. Prostakov, A. V. Varlomov and G. A. Vasilev,
Khim., Geterotsikl. Soedin
., 6, 787 (Russian) 1977, JP 53015385 (February 1978); D. V. Sokolov, M. N. Akimova, K. D. Praliev, V. M. Kurilenko, Zh. N. Khlienko and K M. Moiseeva, Khim.-Farm. Zh. 11, 47 (Russian) 1977; P. Hrdlovic and S. Chmela,
Int. J. Polym. Mater
., 13, 245 (1990); J. Pan, Z. Yang, L. Tong, W. Lau, W. Y. Wayne and C. S. Lee,
Polym. Degrad. Stab
. 44, 85, 1994; disclose the preparation and the mechanism of application of HALS derivatives.
Some of the authors have reported vinylic derivatives of HALS as polymerizable light stabilizers wherein, the vinyl group is attached to the hindered nitrogen atom. One of the vinylic derivative of HALS having formula
is disclosed in the patent EP 24999145 A1 (December 1987). Upon UV irradiation under atmospheric condition; the hindered nitrogen bearing the vinyl group gets converted into nitroxyl radical (N—O*).
As a result of which the hindered amine moiety gets detached from the covalently bonded vinyl group attached to the surface and is thus prone to be lost due to leaching/extraction/evaporation (shown in the Scheme 1), making it inefficient. The objective of the present invention is therefore, to provide a process for the preparation of novel vinylic HALS, which can the firmly bound to the polymer surface. Moreover, this class of monomeric HALS are known to be compatible with polyolefins, polystyrene and diene clastomers and can even be co-polymerized in a desired proportion to obtain ‘in chain’ and ‘chain end’ radical scavengers.
DESCRIPTION OF THE INVENTION
Accordingly the present invention provides novel vinylic Hindered Amine Light Stabilizers derivatives having general formula (I):
R
1
is C
1
to C
8
: alkyl, alkoxy, alkyl phenyl, hydroxy alkyl (all linear and branched), allyl, acyl, cycloalklyl (cyclopentyl, cyclohexyl or cumyl: linear and branched); R
2
is hydrogen and methyl, R
3
is vinyl, C
1
-C
4
vinyl alkyl [H
2
C═C(R
4
)C
1
-C
4
], R
4
is H, C
1
-C
4
allyl and alkyl phenyl and R
5
is H, C
1
-C
4
alkyl, X is O, N C
1
-C
8
alkyloxy and alkylamino: (linear or branched).
In one of the other embodiments of the present invention, the carbonyl compound having formula (III) used to react with compound having formula (II) is selected from formalin, formaldehyde, acetaldehyde, benzaldehyde, methyl ethyl ketone, methyl benzyl ketone, cyclohexyl methyl ketone.
In yet another embodiments of the present invention, the organic solvent used for extracting the products is selected from the group consisting of diethylether; dieliloromethane, ethyl acetate and benzene.
In another embodiment the catalyst use is selected from the group consisting of alkyl substituted amino pyridines exemplified by N,N-dimethyl-4-aminopyridine-(DMAP) 4-amino pyridine and 2-mercaptobenzoxazole.
In yet another embodiment the dry organic sloven used to dissolve the catalyst and compound (IV) is selected from the group consisting of dieliloromethane dichloroethane, carbon tetrachloride, cyclohexane, n-hexane and chlorobenzene.
In still another embodiment the base used is selected from aliphatic and aromatic substituted amine selected from the group consisting of triethyl amine, trimethyl amine 2,6-lutidine and pyridine.
In another embodiment the compound (V) added to react with compound (IV) is selected from the group consisting of acryloyl chloride, methacryloyl chloride, pentenoyl chloride and 3-butenoyl chloride-3-phenyl.
In yet another embodiment the inert gas used is selected from Nitrogen and Argon.
In yet another embodiment the inorganic base used to neutralize the solvent fraction containing the product is selected from the group consisting of sodium carbonate and pottassium sodium bicarbonate, potassium carbonate.
HALS monomers and some of its derivatives may be prepared by any of the methods known in the art including those disclosed in Patents No. JP 53015385 28 (July 1978), Swiss CH 610898 (May 15, 1979), Swiss CH 605927 (October 1978), Brit. GB 1492494 (November 1977) and Literature: T. Tsuchiya and H. Sashida,
Heterocycles
, 14, 1925-8 (1980). All these patents are incorporated herein by reference. HALS namely 2,2,6,6-tetramethyl piperidine and 2,2,6,6-tetramethyl-4-piperidinol may be prepared by synthetic route disclosed by W. B. Lutz, S. Lazams and R. I. Meltzer,
J. Org. Chem
., 14, 530 (1949). All these patents and literature are incorporated herein by reference The present invention is described herein below with references to examples which are illustrative only and should not be construed to limit the scope of the present invention in any manner whatsoever.


REFERENCES:
patent: 3904581 (1975-09-01), Murayama et al.
patent: 4210612 (1980-07-01), Karrer
patent: 4256627 (1981-03-01), Moser et al.
patent: 4294949 (1981-10-01), Karrer
patent: 4344876 (1982-08-01), Berner
patent: 4880859 (1989-11-01), Slongo et al.
patent: 5047489 (1991-09-01), Ravichandran et al.
patent: 1401924 (1975-08-01), None

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