U.S. patent number RE33,489 [Application Number 07/411,962] was granted by the patent office on 1990-12-11 for photolytically cleavable, n-acylated sterically hindered amines.
This patent grant is currently assigned to Ciba-Geigy Corporation. Invention is credited to Godwin Berner, Mario Slongo.
United States Patent |
RE33,489 |
Berner , et al. |
December 11, 1990 |
Photolytically cleavable, N-acylated sterically hindered amines
Abstract
Sterically hindered cyclic amines which are substituted by a
photoactivatable acyl group at the basic nitrogen atom can be
deacylated by irradiation with UV light. This is advantageous if
the basicity of the amines proves troublesome during application.
Examples of such photoactivatable acyl groups are phenylglyoxyl,
phenylacetyl or naphthylacetyl groups.
Inventors: |
Berner; Godwin (Binningen,
CH), Slongo; Mario (Tafers, CH) |
Assignee: |
Ciba-Geigy Corporation
(Ardsley, NY)
|
Family
ID: |
4260940 |
Appl.
No.: |
07/411,962 |
Filed: |
September 25, 1989 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
899133 |
Aug 21, 1986 |
04785102 |
Nov 15, 1988 |
|
|
Foreign Application Priority Data
|
|
|
|
|
Aug 27, 1985 [CH] |
|
|
3668/85 |
|
Current U.S.
Class: |
546/20; 544/137;
544/157; 544/198; 546/188; 546/22 |
Current CPC
Class: |
C07D
211/46 (20130101); C07D 235/02 (20130101); C07D
471/10 (20130101); C08K 5/3435 (20130101) |
Current International
Class: |
C07D
235/02 (20060101); C07D 211/00 (20060101); C07D
211/46 (20060101); C07D 235/00 (20060101); C07D
471/00 (20060101); C07D 471/10 (20060101); C08K
5/00 (20060101); C08K 5/3435 (20060101); C07D
471/10 () |
Field of
Search: |
;546/20,22,188
;544/198,337,357 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Chemical Abstracts, vol. 100, (1984), Abstracting Japanese Kokai
Tokkyo Koho JP 58,29,033 [83, 29033] May 12, 1983, (Item 104558n).
.
Chemical Abstracts, vol. 103, (1985), Abstracting Japanese Kokai
Tokkyo Koho JP 59,116,747 [84, 116,747], Jul. 5, 1984, (Item
96306y). .
Chemical Abstracts, vol. 97, (1982), Abstracting Eur. Patent Appln.
EP No. 52,073, published May 19, 1982, (Item 73998u). .
Chemical Abstracts, vol. 99, (1983), Abstracting Eur. Patent Appln.
EP No. 83,308, published Jul. 6, 1983, (Item 100958f). .
Synthesis, (Aug. 1981), pp. 616-620, Cabre-Castellvi et al. .
J. Am. Chem. Soc., vol. 82, pp. 1600-1607, (1960). .
Eur. J. Med. Chem., pp. 188-192, (1974)..
|
Primary Examiner: Bond; Robert T.
Attorney, Agent or Firm: Villamizar; JoAnn
Claims
What is claimed is:
1. A compound of formula I ##STR14## wherein m is 1, 2 or 3,
A is a R.sup.1 --CO-- or R.sup.2 --CH.sub.2 -- group, wherein
R.sup.1 is phenyl or phenyl which is substituted by halogen,
C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.4 alkoxy or hydroxy, or is
naphthyl.[., C.sub.1 -C.sub.12 alkoxy, cyclohexyloxy, phenoxy or
benzyloxy.]. and, if m=1, may also be a radical B,
R.sup.2 is --CN, --P(O)(OR.sup.3).sub.2, CH.sub.3 CO-- or OR.sup.4,
wherein
R.sup.3 is C.sub.1 -C.sub.4 alkyl or phenyl, and
R.sup.4 is phenyl or phenyl which is substituted by halogen or
C.sub.1 -C.sub.4 alkyl, and
when m is 1,
B is a radical corresponding to the formulae ##STR15## wherein
R.sup.5 is hydrogen, --OR.sup.8, ##STR16## --N(R.sup.10 R.sup.11),
R.sup.6 is --OH or --OR.sup.12 and R.sup.7 is --OR.sup.12, --CN,
--COOR.sup.13 or --CONH.sub.2, or R.sup.6 and R.sup.7 together are
the oxo radical (.dbd.O), or R.sup.6 and R.sup.7, together with the
C-atom to which they are attached, form an unsubstituted
2-spiro-1,3-dioxolane, 2-spiro-1,3-dioxane,
5-spiro-1,3-oxazolidine, 2-spiro-1,3-oxazolidine or
5-spiro-1,3-imidazolidine ring or said ring substituted by one or
more identical or different members selected from C.sub.1 -C.sub.12
alkyl or the oxo radical,
R.sup.8 is C.sub.1 -C.sub.12 alkyl, benzyl, allyl or
2-cyanoethyl,
R.sup.9 is C.sub.1 -C.sub.18 alkyl, C.sub.2 -C.sub.12 alkenyl,
C.sub.5 -C.sub.8 cycloalkyl, phenyl or phenyl which is substituted
by halogen, C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.4 alkoxy or
hydroxyl, or is C.sub.7 -C.sub.12 phenylalkyl, C.sub.1 -C.sub.4
alkoxy or phenoxy,
R.sup.10 is C.sub.1 -C.sub.12 alkyl, cyclohexyl, phenyl, naphthyl,
or phenyl which is substituted by C.sub.1 -C.sub.4 alkyl,
R.sup.11 is C.sub.2 -C.sub.12 alkanoyl, C.sub.3 -C.sub.8 alkenoyl,
benzoyl or a group of the formula ##STR17## wherein R.sup.14 and
R.sup.15 are each independently of the other C.sub.1 -C.sub.8
alkoxy, phenoxy, or a group --N(R.sup.10)(R.sup.16), in which
R.sup.16 is hydrogen or C.sub.1 -C.sub.12 alkyl,
R.sup.12 is C.sub.1 -C.sub.12 alkyl and R.sup.13 is C.sub.1
-C.sub.4 alkyl, and
Y is hydrogen, C.sub.1 -C.sub.12 alkyl, allyl or benzyl;
when m is 2,
B is a divalent radical corresponding to the formulae ##STR18##
wherein Z is --O--, --NH-- or --NR.sup.10 --,
R.sup.17 is methylene, 1,2-ethylene, C.sub.3 -C.sub.20
polymethylene, or branched C.sub.3 -C.sub.20 alkylene, C.sub.2
-C.sub.10 alkenylene, 1,4-cyclohexylene, 1,3-cyclohexylene,
cyclohexane-1,4-dimethylene, 1,3- or 1,4-phenylene, 1,4- or
1,5-naphthylene, 4,4'-diphenylene, diphenylmethane-4,4'-diyl,
diphenyl oxide-4,4'-diyl or m- or p-xylene, or a radical
--NR--R.sup.19 --NH--,
R.sup.18 is 1,2-ethylene, 1,2-propylene, 1,3-propylene,
1,2-butylene, 1,4-butylene, hexamethylene, 1,4-cyclohexylene or
cyclohexane-1,4-dimethylene,
R.sup.19 is 1,2-ethylene, trimethylene, tetramethylene,
hexamethylene, oxtamethylene, dodecamethylene,
2,2-dimethyltrimethylene, trimethyloctamethylene,
1,4-cyclohexylene, cyclohexane-1,4-dimethylene, 1,3-phenylene,
4,4'-diphenylene, diphenylmethane-4,4'-diyl, diphenyl
oxide-4,4'-diyl, or m- or p-xylylene, and
R.sup.10 and R.sup.14 are as defined above;
and, when m is 3,
B is a trivalent radical corresponding to the formulae ##STR19##
wherein R.sup.20 is propane-1,2,3-triyl, butane-1,2,4-triyl,
benzene-1,3,5-triyl, benzene-1,2,4-triyl or
naphthalene-1,4,5-triyl, R.sup.21 is a 1,3,5-triazin-2,4-triyl
radical and Z is as defined above.
2. A compound according to claim 1 of formula I, wherein A is a
R.sup.1 --CO-- or R.sup.2 --CH.sub.2 --group, wherein R.sup.1 is
phenyl which is substituted by halogen, C.sub.1 -C.sub.12 alkyl or
C.sub.1 -C.sub.4 alkoxy, or is unsubstituted naphthyl, and R.sup.2
is --CN or CH.sub.3 CO--.
3. A compound according to claim 1 of formula I, wherein A is a
benzoyl group.
4. A compound according to claim 1 of formula I, wherein m is 1 or
2 and B is a group of formula II, III or IV.
5. A compound according to claim 4 of the formula ##STR20##
Description
The present invention relates to photolytically cleavable,
N-acylated sterically hindered amines and to the use thereof for
stabilising polymers against light-induced damage, in particular
for stabilising acid curable resins.
It is known that sterically hindered amines are effective light
stabilisers for polymers. Particular importance attaches to the
light protection of varnishes for producing industrial finishes of
which a long service life is required, e.g. automotive finishes or
machine finishes. Acid-catalysed stoving varnishes are often used
for obtaining such finishes. The addition of acid curing catalysts
as well as amine light stabilisers to such varnishes before curing
may result in unwanted interactions of both these components. This
problem can be overcome by using N-acylated piperidines as "amine
light stabilisers" in accordance with the teaching of European
patent application No. EP-A-52 073. These compounds are no longer
basic and thus do not give rise to interactions with acid
catalysts. However, the light protective action of the N-acylated
piperidines is usually inferior to that of the analogous
N-unsubstituted or N-alkylated piperidines. The problem was
therefore to provide light stabilisers which do not undergo
interaction with the acid catalyst and which induce in the cured
varnish as good a light-stabilising effect as the N-unsubstituted
or N-alkylated amine light stabilisers. The same consideration also
applies to acid curable resins, aside from their utility as
varnishes.
It has been found that this problem can be solved by using
N-acylated, sterically hindered amines as light stabilisers, which
amines can be cleaved by photolysis and converted into
N-unsubstituted amine light stabilisers after curing the resin by
irradiation. These photolytically curable amine light stabilisers
are so far not known in the art and therefore had to be developed
specially for this purpose.
Accordingly, the invention relates to compounds of formula I
##STR1## wherein m is 1, 2 or 3,
A is a R.sup.1 --CO-- or R.sup.2 --CH.sub.2 -- group, wherein
R.sup.1 is phenyl or phenyl which is substituted by halogen,
C.sub.1 -C.sub.12 -alkyl, C.sub.1 -C.sub.4 alkoxy or hydroxy, or is
naphthyl, C.sub.1 -C.sub.12 alkoxy, cyclohexyloxy, phenoxy or
benzyloxy and, if m=1, may also be a radical B,
R.sup.2 is halogen, phenyl, naphthyl, --CN, --P(O)(OR.sup.3).sub.2,
--CH.sub.3 CO-- or --OR.sup.4, wherein
R.sup.3 is C.sub.1 -C.sub.4 alkyl or phenyl, and
R.sup.4 is phenyl or phenyl which is substituted by halogen or
C.sub.1 -C.sub.4 alkyl, and
B is a radical of valency m of a sterically hindered cyclic amine
which is attached to the A--CO-- radical through the sterically
hindered nitrogen atom.
The cyclic amine radical B can be a 5-, 6- or 7-membered ring which
may also contain other hetero atoms in addition to the basic
nitrogen atom. However, the radical B is not an aromatic
heterocyclic radical. In particular, where m=1, B may be a radical
of formula ##STR2## wherein R.sup.5 is hydrogen, --OR.sup.8,
##STR3## --N(R.sup.10 R.sup.11), R.sup.6 is --OH or --OR.sup.12 and
R.sup.7 is --OR.sup.12, --CN, --COOR.sup.13 or --CONH.sub.2, or
R.sup.6 and R.sup.7 together are the oxo radical (.dbd.O), or
R.sup.6 and R.sup.7, together with the C-atom to which they are
attached, form a heterocyclic spiro ring which may be a
2-spiro-1,3-dioxolane, 2-spiro-1,3-dioxane,
5-spiro-1,3-oxazolidine, 2-spiro-1,3-oxazolidine or
5-spiro-1,3-imidazolidine ring and which may be substituted by one
or more identical or different members selected from alkyl,
substituted alkyl, alkylene and/or the oxo radical,
R.sup.8 is C.sub.1 -C.sub.12 alkyl, benzyl, allyl or
2-cyanoethyl,
R.sup.9 is C.sub.1 -C.sub.18 alkyl, C.sub.2 -C.sub.12 alkenyl,
C.sub.5 -C.sub.8 cycloalkyl, phenyl or phenyl which is substituted
by halogen, C.sub.1 -C.sub.12 alkyl, C.sub.1 -C.sub.4 alkoxy and/or
hydroxyl, or is C.sub.7 -C.sub.12 phenylalkyl, C.sub.1 -C.sub.4
alkoxy or phenoxy,
R.sup.10 is C.sub.1 -C.sub.12 alkyl, cyclohexyl, phenyl, naphthyl,
or phenyl which is substituted by C.sub.1 -C.sub.4 alkyl,
R.sup.11 is C.sub.2 -C.sub.12 alkanoyl, C.sub.3 -C.sub.8 alkenoyl,
benzoyl or a group of the formula ##STR4## wherein R.sup.14 and
R.sup.15 are each independently of the other C.sub.1 -C.sub.8
alkoxy, phenoxy, or a group --N(R.sup.10)(R.sup.16), in which
R.sup.16 is hydrogen or C.sub.1 -C.sub.12 alkyl,
R.sup.12 is C.sub.1 -C.sub.12 alkyl and R.sup.13 is C.sub.1
-C.sub.4 alkyl, and
Y is hydrogen, C.sub.1 -C.sub.12 alkyl, allyl or benzyl.
Where m is 2, B may in particular be a divalent radical selected
from: ##STR5## wherein Z is --O--, --NH-- or --NR.sup.10,
R.sup.17 is a divalent aliphatic, cycloaliphatic or aromatic
radical of 1 to 20 carbon atoms or a radical --NH--R.sup.19
--NH--,
R.sup.18 is a divalent aliphatic or cycloaliphatic or aromatic
radical of 2 to 12 carbon atoms,
R.sup.19 is a divalent aliphatic, cycloaliphatic or aromatic
radical of 2 to 16 carbon atoms, and
R.sup.10 and R.sup.14 are as previously defined.
Where m=3, B may be in particular a trivalent radical of formula
##STR6## wherein R.sup.20 is a trivalent aliphatic radical of 3 to
8 carbon atoms or a trivalent aromatic radical of 6 to 10 carbon
atoms, R.sup.21 is a 1,3,5-triazin-2,4,6-triyl radical, and Z is as
previously defined.
Substituents defined above as alkyl may be unbranched or branched
alkyl. R.sup.3 and R.sup.13 as C.sub.1 -C.sub.4 alkyl are methyl,
ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or
tert-butyl. R.sup.8, R.sup.10, R.sup.12, R.sup.16 and Y as C.sub.1
-C.sub.12 alkyl may be pentyl, n-hexyl, 2-ethylbutyl, n-octyl,
2-ethyl-n-hexyl, n-nonyl, isodecyl or n-dodecyl. R.sup.9 as C.sub.1
-C.sup.18 alkyl may be tetradecyl, hexadecyl or octadecyl.
R.sup.9 as C.sub.2 -C.sub.12 alkyl may be vinyl, allyl, 2-propenyl,
methallyl, 2-buten-1-yl, 2-buten-2-yl, 2-hexen-1-yl, 2-octen-1-yl
or 10-un-decen-1-yl.
R.sup.9 as C.sub.5 -C.sub.6 cycloalkyl may be cyclopentyl,
cyclohexyl, methylcyclohexyl or cyclooctyl. R.sup.9 as C.sub.7
-C.sub.12 phenylalkyl may be benzyl, 1- or 2-phenylethyl or
3-phenylpropyl.
R.sup.1, R.sup.4 and R.sup.9 as substituted phenyl radicals may be
4-chlorophenyl, 3-bromophenyl, 2-fluorophenyl, 4-methylphenyl,
2,4-dimethylphenyl, 4-tert-butylphenyl, 3-methoxyphenyl or
4-ethoxyphenyl. R.sup.1 and R.sup.9 may also be 4-octylphenyl,
4-dodecylphenyl, 4-hydroxyphenyl, 2-methyl-4-hydroxyphenyl or
3,5-di-(tert-butyl)-4-hydroxyphenyl.
R.sup.9, R.sup.14 and R.sup.15 as alkoxy radicals may be methoxy,
ethoxy or butoxy. R.sup.14 and R.sup.15 may also be hexyloxy,
octyloxy, decyloxy or dodecyloxy.
R.sup.11 as alkanoyl or alkenoyl may be acetyl, propionyl,
butyroyl, hexanoyl, octanoyl, lauroyl, acryloyl, methacryloyl or
crotonoyl.
R.sup.17 as a divalent aliphatic, cycloaliphatic or aromatic
radical may be methylene, 1,2-ethylene or C.sub.3 -C.sub.20
polymethylene; or branched C.sub.3 -C.sub.20 alkylene such as
1,2-propylene or trimethyltetramethylene; or C.sub.2 -C.sub.10
alkenylene such as vinylene or 2-buten-1,4-ylene; or cycloalkylene
such as 1,4-cyclohexylene or 1,3-cyclohexylene; or
cycloalkane-dialkylene such as cyclohexane-1,4-dimethylene; or
arylene such as 1,3- or 1,4-phenylene, 1,4- or 1,5-naphthylene,
4,4'-diphenylene, diphenylmethane-4,4'-diyl or diphenyl
oxide-4,4'-diyl; or aralkylene such as m- or p-xylene.
R.sup.18 as a divalent aliphatic, cycloaliphatic or aromatic
radical is preferably a radical of 2 to 8 carbon atoms. Examples of
such radicals are 1,2-ethylene, 1,2-propylene, 1,3-propylene,
1,2-butylene, 1,4-butylene, hexamethylene, 1,4-cyclohexylene or
cyclohexane-1,4-dimethylene.
R.sup.19 as a divalent aliphatic, cycloaliphatic or aromatic
radical may be an unbranched or branched alkylene radical such as
1,2-ethylene, trimethylene, tetramethylene, hexamethylene,
octamethylene, dodecamethylene, 2,2-dimethyltrimethylene or
trimethyloctamethylene; or a cycloalkylene radical such as
1,4-cyclohexylene; or cycloalkanealkylene such as
cyclohexane-1,4-dimethylene; or arylene such as 1,3-phenylene,
4,4'-diphenylene, diphenylmethane-4,4'-diyl or diphenyl
oxide-4,4'-diyl; or arene-dialkylene such as m- or p-xylylene.
R.sup.20 as a trivalent aliphatic or aromatic radical may be
propane-1,2,-3-triyl, butane-1,2,4-triyl, benzene-1,3,5-triyl,
benzene-1,2,4-triyl or naphthalene-1,4,5-triyl.
Preferred compounds of formula I are those wherein A is a R.sup.1
--CO-- or R.sup.2 --CH.sub.2 -- group, wherein R.sup.1 is phenyl or
phenyl which is substituted by halogen, C.sub.1 -C.sub.12 alkyl or
C.sub.1 -C.sub.4 alkoxy, or is unsubstituted naphthyl, and R.sup.2
is phenyl, naphthyl, --CN or CH.sub.3 CO--.
Particularly preferred compounds of formula I are those wherein A
is a benzoyl group or an .alpha.-naphthylmethyl group. Further
preferred compounds of formula I are those wherein m is 1 or 2 and
B is a group of formulae II, III or IV.
Where m=1 and A is B--CO, the compounds conform to the formula
B--CO--CO--B, wherein both radicals B are attached to the --CO
group through their sterically hindered nitrogen atoms.
The compounds of formula I can be prepared in principle from the
N-unsubstituted amines (H).sub.m B by reaction with the
corresponding carboxylic acid chlorides A--COCl or anhydrides
(A--CO).sub.2 O. The compounds B--CO--CO--B can be prepared by
reaction of 2 moles of H--B with 1 mole of oxalyl chloride. The
N-unsubstituted sterically hindered cyclic amines are known
compounds which have been described in a number of patent
specifications, for example U.S. Pat. Nos. 3,640,928, 3,790,525 and
3,639,409.
Some of the acid chlorides A--COCl are known compounds or can be
prepared from the corresponding carboxylic acids by known methods,
for example by reaction with thionyl chloride. Some of the
anhydrides are also known and can be prepared e.g. by the method
described in J. Cabre-Castelvi et al., in Synthesis, 1981, 616.
Representative examples of individual compounds of formula I are
listed below. In these compounds, ##STR7## denotes a
2,2,6,6-tetramethylpiperidine radical Ph- is a phenyl radical and
Naphth- is an .alpha.-naphthyl radical. ##STR8##
The compounds of formula I are intrinsically light stabilisers for
organic polymers and can be used for stabilising them without the
need for irradiation. To this end they are normally incorporated in
the polymers before these are processed to moulded articles.
However, they can also be added during the manufacture of the
polymers. The following classes of polymer are examples of polymers
which are sensitive to the action of light and which can be
stabilised by addition of the compounds of this invention.
1. Polymers of mono- and diolefins, for example polyethylene
(uncrosslinked or crosslinked), polypropylene, polyisobutylene,
polybut-1-ene, polymethylpent-1-ene, polyisoprene or polybutadiene,
and polymers of cycloolefins, e.g. of cyclopentene or
norbornene.
2. Mixtures of the polymers mentioned under (1), for example
mixtures of polypropylene with polyethylene or with
polyisobutylene.
3. Copolymers of mono- and diolefins with each other or with other
vinyl monomers, for example ethylene/propylene copolymers,
propylene/but-1-ene copolymers, propylene/isobutylene copolymers,
ethylene/but-1-ene copolymers, propylene/butadiene copolymers,
isobutylene/isoprene copolymers, ethylene/alkylacrylate copolymers,
ethylene/alkylmethacrylate copolymers, ethylene/vinyl acetate
copolymers, or ethylene/acrylic acid copolymers and salts thereof
(isomers), as well as terpolymers of ethylene with propylene and a
diene such as hexadiene, dicyclopentadiene or ethylidene
norbornene.
4. Polystyrene, poly-(p-methylstyrene).
5. Copolymers of styrene or .alpha.-methylstyrene with dienes or
acrylic derivatives, for example styrene/butadiene,
styrene/acrylonitrile, styrene/alkylmethacrylate,
styrene/acrylonitrile/methyl acrylate, mixtures of high impact
strength obtained from styrene copolymers and another polymer, for
example a polyacrylate, a diene polymer or an
ethylene/propylene/diene terpolymer; and also block copolymers of
styrene, for example styrene/butadiene/styrene,
styrene/isoprene/styrene, styrene/ethylene/butylene/styrene, or
styrene/ethylene/propylene/styrene.
6. Graft copolymers of styrene, e.g. styrene with polybutadiene,
styrene and acrylonitrile with polybutadiene, styrene and maleic
anhydride with polybutadiene, styrene and alkyl acrylates or alkyl
methacrylates with polybutadiene, styrene and acrylonitrile with
ethylene/propylene/diene terpolymers, styrene and acrylonitrile
with polyalkylacrylates or polyalkylmethacrylates, styrene and
acrylonitrile with acrylate/butadiene copolymers, and mixtures
thereof with the copolymers listed under (5), known e.g. as ABS,
MBS, ASA or AES polymers.
7. Halogen-containing polymers, e.g. polychloroprene, chlorinated
rubber, chlorinated or chlorosulfonated polyethylene, especially
polymers of halogenated vinyl compounds, e.g. polyvinyl chloride,
polyvinylidene chloride, polyvinyl fluoride, polyvinylidene
fluoride and their copolymers such as vinyl chloride/vinylidene
chloride, vinyl chloride/vinyl acetate or vinylidene chloride/vinyl
acetate polymers.
8. Polymers which are derived from .alpha.,.beta.-unsaturated acids
and their derivatives, e.g. polyacrylates and polymethacrylates,
polyacrylamides and polyacrylonitriles.
9. Copolymers of the monomers listed in (8) with one another or
with other unsaturated monomers, e.g. acrylonitrile/butadiene
copolymers, acrylonitrile/alkylacrylate copolymers,
acrylonitrile/vinyl halide copolymers, or
acrylontrile/alkylmethacrylate/butadiene terpolymers.
10. Polymers which are derived from unsaturated alcohols and amines
or their acyl derivatives or acetals, e.g. polyvinyl alcohol,
polyvinyl acetate, polyvinyl stearate, polyvinyl benzoate,
polyvinyl maleate, polyvinylbutyral, polyallyl phthalate, polyallyl
melamine.
11. Homopolymers and copolymers of cyclic ethers such as
polyethylene glycols, polyethylene oxide, polypropylene oxide or
their copolymers with bisglycidyl ethers.
12. Polyacetals such as polyoxymethylene, and also those
polyoxymethylenes which contain e.g. ethylene oxide as
comonomer.
13. Polyphenyl oxides and polyphenyl sulfides and mixtures thereof
with styrene polymers.
14. Polyurethanes which are derived on the one hand from
polyethers, polyesters and polybutadienes containing hydroxy end
groups, and from aliphatic or aromatic polyisocyanates on the
other, as well as their precursors (polyisocyanates, polyols,
prepolymers).
15. Polyamides and copolyamides which are derived from diamines and
dicarboxylic acids and/or from aminocarboxylic acids or the
corresponding lactams, such as polyamide 4, polyamide 6, polyamide
66, polyamide 610, polyamide 11, polyamide 12,
poly-2,4,4-trimethylhexamethyleneterephthalamide,
poly-m-phenylene-isophthalamide, and their block copolymers with
polyethers, e.g. with polyethylene glycol, polypropylene glycol or
polytetramethylene glycol.
16. Polyureas, polyimides and polyamide-imides.
17. Polyesters which are derived from dicarboxylic acids and diols
and/or from hydroxycarboxylic acids or the corresponding lactones,
e.g. polyethylene terephthalate, polybutylene, terephthalate,
poly-1,4-dimethylolcyclohexane terephthalate, polyhydroxybenzoates,
and also block polyether esters which are derived from
hydroxyl-terminated polyethers.
18. Polycarbonates.
19. Polysulfones, polyether sulfones and polyether ketones.
20. Crosslinked polymers which are derived from aldehydes on the
one hand and from phenols, ureas and melamines on the other hand,
e.g. phenol/formaldehyde resins, urea/formaldehyde resins and
melamine/formaldehyde resins.
21. Drying and non-drying alkyd resins.
22. Unsaturated polyester resins which are derived from
copolyesters of saturated and unsaturated dicarboxylic acids with
polyhydric alcohols and from vinyl compounds as crosslinking
agents, and also their halogen-containing modifications of low
combustibility.
23. Crosslinkable acrylic resins which are derived from substituted
acrylic esters, e.g. from epoxy acrylates, urethane acrylates or
polyester acrylates.
24. Alkyd resins, polyester resins and acrylate resins which are
crosslinked with melamine resins, urea resins, polyisocyanates or
epoxy resins.
25. Crosslinked epoxy resins which are derived from polyepoxides,
e.g. bisglycidyl ethers, or from cycloaliphatic diepoxides.
26. Naturally occurring polymers such as cellulose, natural rubber
and gelatin, and also chemically modified homologous derivatives
thereof such as cellulose acetates, cellulose propionates and
cellulose butyrates, and cellulose ethers such as
methylcellulose.
The amount of stabiliser added is in general 0.01 to 5% by weight,
preferably 0.03 to 1.5% by weight and, most preferably, 0.2 to 0.6%
by weight, based on the polymer to be stabilised.
The polymers may also contain other known stabilisers, for example
antioxidants, light stabilisers, metal deactivators, phosphites,
thiodicarboxylates, salts of higher fatty acids or other
co-stabilisers. Other modifiers conventionally employed in plastics
technology may also be added, for example antistats, plasticizers,
lubricants, flame retardants, pigments, reinforcing agents or
fillers.
If the stabilised polymers are in the form of thin layers, as they
are in the case of sheets, filaments, varnishes and coatings, the
stabilisers of formula I can be cleaved photochemically by
irradiation with shortwave light to form compounds which are
unsubstituted at the sterically hindered nitrogen atom. Irradiation
is preferably effected with UV light in the wavelength range from
250 to 400 nm. Suitable light sources for the irradiation are for
example medium-pressure, high-pressure and low-pressure mercury
lamps as well as superactinic neon tubes. At the present time a
whole range of suitable devices is available, especially for
continuous irradiation, in which the material to be irradiated is
transported beneath the light source. The same effect is achieved
when using the stabilised polymers in the open.
As mentioned at the outset, the photochemical conversion of the
N-acylated stabiliser to an N-unsubstituted stabiliser is of
particular importance for stabilising acid-catalysed stoving
varnishes by effecting irradiation after stoving.
Acid-curable varnishes are in particular those based on a binder
that contains an amine resin, e.g. an etherified, esterified or
otherwise modified melamine resin, urea resin or guanidine resin.
These varnishes are normally used in admixture with alkyd,
polyester or acrylic resins which contain functional groups (e.g.
--OH or --COOH groups) that are crosslinked by reaction with the
methylol groups of the amine resins. This crosslinking is catalysed
by acids. Instead of the amine resin, the varnish can also contain
methylol derivatives of polycarboximides or their ethers or esters.
Sulfonic acids are usually employed as acid curing catalysts, but
carboxylic acids or phosphonic acids or masked sulfonic acids are
also suitable.
Acid-catalysed stoving varnishes often contain mixtures of alkyd
resins, polyester resins and acrylic resins with one another or
with other film-forming resins. Such film-forming resins may also
be self-crosslinking, for example if they are modified by
methylolamide groups, in which case they do not require the
addition of an amine resin or other crosslinking agent.
The stabilisers of this invention are incorporated in the varnishes
before application, preferably by adding them to a solution of the
stabiliser in an organic solvent. The stoving of the varnish is
usually effected in the temperature range from
100.degree.-200.degree. C. During stoving, the stabiliser must not
volatilise and decompose. Not until the subsequent irradiation of
the cured varnish coating does the photochemical cleavage of the
stabilise occur.
For many finishes, especially automotive finishes, the two-coat
method is employed at the present time. This method comprises
applying first the pigmented varnish and then the clear varnish to
the undercoat. The light stabiliser can be added to the clear
varnish as well as to the pigmented varnish or to both
coatings.
To obtain maximum light-resistance, the concurrent use of other
conventional light stabilisers, e.g. UV absorbers or organic nickel
compounds, can be advantageous. The concurrent use of UV absorbers
of the 2-hydroxybenzophenone, 2-(2-hydroxyophenyl)benztriazole or
oxanilide type, which may have a synergistic effect, is especially
useful. Examples of such compounds are:
2-(2-hydroxy-3,5-di-tert-amylphenyl)benztriazole,
2-(2-hydroxy-5-tert-octylphenyl)benztriazole,
2-(2-hydroxy-3,5-di-tert-octylphenyl)benztriazole,
2,4-dihydroxybenzophenone, 2-hydroxy-4-octyloxybenzophenone,
2-hydroxy-5-dodecyloxybenzophenone,
2-ethyl-2-ethoxy-4'-tert-butyloxalanilide or
2-ethyl-2'-ethoxyoxalanilide.
When using such combinations, the sum of all light stabilisers is
0.2 to 5% by weight, preferably 0.5 to 2% by weight, based on the
film-forming resin.
Further modifiers which may be present in the varnish are
antioxidants, for example of the sterically hindered phenol
derivative type, phosphorus compounds such as phosphites or
phosphonites, plasticisers, levelling agents, thickeners,
dispersants or bonding agents.
The following Examples illustrate the preparation of the compounds
of this invention and the use thereof as stabilisers.
EXAMPLE 1
(a) 1 ml of piperidine is added to 30 g (0.2 mole) of
phenylglyoxylic acid and 18.9 ml (0.26 mole) of thionyl chloride
are added dropwise, with stirring, under nitrogen such that the
temperature of the reaction mixture is 25.degree.-30.degree. C. The
reaction mixture is then stirred for 24 hours at
35.degree.-40.degree. C. and concentrated by evaporation at a
maximum temperature of 40.degree. C. under vacuum. The residual
crude phenylglyoxylyl chloride is a yellow oil containing an
insignificant amount of powdery deposit. This crude product is used
without further purification for the subsequent reactions.
(b) 24.1 g (0.1 mole) of 4-hexyloxy-2,2,6,6-tetramethylpiperidine
are dissolved in 100 ml of absolute methylene chloride. To this
solution are added 15.2 g (0.15 mole) of absolute triethylamine and
the whole solution is cooled to -10.degree. C. At this temperature
a solution of 16.8 g (0.1 mole) of phenylglyoxylyl chloride in 100
ml of methylene chloride is slowly added dropwise. When this
addition is complete, the reaction mixture is allowed to warm to
room temperature and stirred for about 4 hours. Precipitated
hydrochloride is removed by filtration and the solution is
clarified by filtration over a small amount of silica gel and
concentrated by evaporation, affording 28.4 g of
1-(4-hexyloxy-2,2,6,6-tetramethylpiperidino)-2-phenylethane-1,2-dione
as a yellow oil (stabiliser 1).
______________________________________ Analysis: theory C = 73.96%
found C = 73.77% H = 9.44% H = 9.20% N = 3.75% N = 3.25%
______________________________________
Analogous reaction of phenylglyoxylyl chloride with the
corresponding cyclic amines gives the following compounds:
3-dodecyl-8-(2-phenylethane-1,2-dion-1-yl)-7,7,9,9-tetramethyl-1,3,8-triaza
spiro[4.5]decane-2,4-dione (stabiliser 2);
______________________________________ Analysis: theory C = 70.82%
found C = 70.46% H = 9.02% H = 8.82% N = 7.99% N = 7.96%
______________________________________
3-dodecyl-1,8-bis(2-phenylethane-1,2-dion-1-yl)-7,7,9,9-tetramethyl-1,3,8-t
riazaspiro[4.5]decane-2,4-dione (stabiliser 3);
______________________________________ Analysis: theory C = 71.20%
found C = 68.82% H = 7.81% H = 7.72% N = 6.38% N = 6.19%
______________________________________
bis-[1-(2-phenylethane-1,2-dion-1-yl)-2,2,6,6-tetramethylpiperidin-4-yl]adi
pate, m.p. 135.degree.-137.degree. C. (stabiliser 4);
1-(4-benzoyloxy-2,2,6,6-tetramethylpiperidino)-2-phenylethane-1,2-dione,
m.p. 122.degree.-124.degree. C. (stabiliser 5);
1-(4-dodecyloxy-2,2,6,6-tetramethyl(piperidino)-2-phenylethane-1,2-dione
in the form of a yellow oil (stabiliser 6);
______________________________________ Analysis: theory C = 76.10%
found C = 75.78% H = 10.35% H = 10.18% N = 3.06% N = 2.93%
______________________________________
EXAMPLE 2
Analogous reaction of ethyl oxalyl chloride (C.sub.2 H.sub.5
OCOCOCl) with the corresponding cyclic amines gives the following
compounds:
ethyl 2-[4-hexyloxy-2,2,6,6-tetramethylpiperidino]-2-oxoacetate
(stabiliser 7);
______________________________________ Analysis: theory C = 66.82%
found C = 66.80% H = 10.33% H = 10.32% N = 4.10% N = 4.07%
______________________________________
3-dodecyl-8-(ethoxyoxalyl)-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane
-2,4-dione (stabiliser 8) of formula ##STR9## m.p.
81.degree.-82.degree. C. ethyl
2-(4-benzoyloxy-2,2,6,6-tetramethylpiperidino)-2-oxoacetate
(stabiliser 9);
______________________________________ Analysis: theory C = 66.46%
found C = 66.33% H = 7.53% H = 7.56% N = 3.88% N = 3.90%
______________________________________
cyclohexanespiro-2'-[1-(ethoxyoxalyl)-1,3-diazolidin-4-one]-5'-spirocyclohe
xane of formula ##STR10## (stabiliser 10), m.p.
211.degree.-213.degree. C.
bis[1-(ethoxyoxalyl)-2,2,6,6-tetramethylpiperidin-4-yl]adipate
(stabiliser 11), m.p. 74.degree.-76.degree. C.
Analogous reaction with oxalyl chloride gives the following
compounds:
oxalyl di(4-benzoyl-2,2,6,6-tetramethyl)piperidide ##STR11##
(stabiliser 12), m.p. 211.degree.-214.degree. C.
1,1'-oxalyl-bis(2,2-pentamethylene-5,5-pentamethylene-1,3-diazolidin-4-one
##STR12## (stabiliser 13), m.p. 192.degree.-193.degree. C.
EXAMPLE 3
A 750 ml sulfonating flask is charged with 49.7 g (0.19 mole) of
4-benzoyloxy-2,2,6,6-tetramethylpiperidine and 25.4 g (0.1 mole) of
phenylacetic anhydride. The mixture is heated under nitrogen to
150.degree. C. and the resultant orange melt is stirred for 6 hours
at this temperature. After this time, no more starting material can
be detected in a thin-layer chromatogram (in ethyl acetate as
eluant). The melt is allowed to cool and then dissolved in ethyl
acetate. The solution is purified through a column of silica gel
and concentrated by evaporation, affording a yellow resinous
product (stabiliser 14) of formula ##STR13##
______________________________________ Analysis: theory C = 75.96%
found C = 75.75% H = 7.70% H = 7.56% N = 3.69% N = 3.17%
______________________________________
EXAMPLE 4
A two-layer metallic varnish is aplied to aluminium sheets. The
undercoat (20 .mu.m) consists of an aluminum-pigmented varnish
based on a polyester/cellulose acetobutyrate/melamine resin
mixture. A clear varnish (40 .mu.m) based on a hydroxylated acrylic
resin (Macrynal.RTM. SM 510 N, ex Hoechst AG) and a polyisocyanate
(Desmodur.RTM. N 75, ex Bayer AG) is applied as topcoat. A solution
of a stabiliser listed in Table 1 in a 1:1 mixture of ethylene
glycol/xylene is added to the clear varnish. For curing, the
samples are heated to 80.degree. C. for 45 minutes.
The samples are subjected to solar radiation in Florida (5.degree.
south) and the surface gloss is measured at 6 month intervals in
accordance with ASTM Test Method D 523. An unstabilised sample of
the same varnish serves as comparison.
TABLE 1 ______________________________________ 20.degree. Gloss (%)
after Stabiliser 0 6 12 18 24 months
______________________________________ none 96 84 81 59 43 1% of 2
96 87 84 78 73 2% of 2 96 84 84 80 79 2% of 3 96 87 87 81 77
______________________________________
EXAMPLE 5
Samples are prepared using a two-layer metallic stoving varnish
comprising an undercoat (20 .mu.m) of an aluminium-pigmented
polyester/cellulose acetobutyrate/melamine resin varnish and a
topcoat of a clear varnish (40 .mu.m) based on a thermosetting
acrylic resin (Viacryl.RTM. VC 373, ex Vianova) and a melamine
resin (Maprenal.RTM. MF 590, ex Hoechst AG) as crosslinking agent.
A stabiliser listed in Table 2 is added to the acrylic resin. The
samples are stoved for 30 minutes at 130.degree. C.
The samples are exposed in a Xenotest 1200 weathering device and
the 20.degree. gloss is measured at intervals of 800 hours in
accordance with DIN 67 530. The results are reported in Table
2.
TABLE 2 ______________________________________ 20.degree. Gloss (%)
after Stabiliser 0 800 1600 2400 3200 4000 h
______________________________________ none 81 53 26 20 -- -- 1% of
5 87 65 52 35 23 19 1% of 6 88 77 55 42 31 26
______________________________________
Noticeable cracks occur in the samples without stabiliser after
2800 hours exposure to weathering, whereas cracks do not appear in
the stabilised samples until after 5200 hours exposure.
* * * * *