Note: Descriptions are shown in the official language in which they were submitted.
~0')47~3
O.Z. 0050/40451
4-(2'-Ethylhexanoyloxy)-2 2,6,6-tetr~methylpiperidine
and use thereof
It i~ known that tetramethylpiperidine deriva-
tives protect polymers from degradation by light, oxygen
and heat. For instance, DE-C-1,929,928 de~cribes esters
of 2,2,6,6-tetrame~-hylpiperidinol and DE-A-2,258,752
describes l-substituted e~ters of this compound for use
as light stabilizers.
However, the compatibility with the polymers to
be protected and the duration and effectiveness of the
li~ht-stabilizing action of these compounds is not always
satisfactory.
It is an object of the present invention to
provide a new stabilizer which i~ free of the aforemen-
tioned disadvantage~.
We have found, ~urpri~ingly, that this object is
achieved by the novel piperidine compound.
The present invention accordingly provides 4-(2'-
ethylhexanoyloxy)-2,2,6,6-tetramethylpiperidine (I) and
acid addition ~alts thereof.
Surprisingly, (I) gives better stabilization of
plastics ~uch as polyurethanes or polyolefins or of
coatings than the neare~t known e~ters.
The compound according to the present invention
can be pr~pared by art recognized methods, for example by
esterifying 2,2,6,6-tetramethyl-4-piperidinol (II) and 2-
ethylhexanoic acid (IIIj or reactive derivative~ thereof,
~uch a~ the acyl chloride, or by tran~esterifying (II)
with e~ters o~ (III) with lower alcohols such a~ the
methyl-or ethyl ester.
The e~terification of 2,2,6,6-tetramethyl-4-
piperidinol with 2-ethylhexanoyl chloride i8 preferably
carried out in an inert organic solvent, eg. dichloro-
methane, toluene, ethyl acetate, butyl acetate, xylene,
ethylene glycol dimethyl ether or methyl benzoate. An
auxiliary base ~uch a~ triethylamine, tributylamine or
pyridine may be present. If a two-phase ~ystem compri~ing
;~3t)~7~3
- 2 - O.Z. 0050/40451
water and a water-Lmmiscible organic inert solvent is
used, it is also possible to use for example sodium
hydroxide, potassium hydroxide, sodium carbonate or
potassium carbonate as auxiliary base. The esterification
is carried out a~ from -20 to 100C, preferably at from
0 to 50C, in particular at around room temperature.
The reaction of 2,2,6,6-tetramethyl-4-piperidinol
with a lower alkyl ester of 2-ethylhexanoic acid, such as
methyl or ethyl 2-ethylhexanoate, can be carried out in
the presence or preferably in the ab~ence of a solvent.
The reaction is advantageously carried out at from 150C
to 200C, preferably at from 175 to 180C. Advantage-
ously, the reaction mixture contains a catalyst, for
example ~odium ethoxide, ~odium methoxide, ~odium hydrox-
ide or an orthotitanate ~uch as tetrabutyl orthotitanateor tetraisopropyl orthotitanate.
The compound (I) according to the pre~ent inven-
tion is usually isolated and purified by di~tillation.
The compound (I) may be pre~ent as the free base
or a3 the salt. Suitable anions come for example from
inorganic acids, carboxylic acids and sulfonic acids. Of
the salts, those of carboxylic acids and ~ulfonic acid~
are preferred.
Suitable inorganic anions are for example chlor-
ide, bromide, sulfate, methosulfate, tetrafluoborate,phosphate and thiocyanate.
Carboxylic acid anions are for example: formate,
acetate, propisnate, hexanoate, cyclohexanoate, lactate,
stearate, palmitate, dodecylbenzoate, benzoate, acrylate,
methàcrylate, citrate, malonate, succinate and anions of
polycarboxylic acids, such as polyacrylic acid, polymeth-
acrylic acid and (meth)acrylic acid copolymers of up to
3000 COOH groups.
Sulfonic acid anion~ are for example benzene-
sulfonate, tosylate and methanesulfonate.
The present invention al80 relates to the use of(I) for stabilizing pla tics and coating~, in particular
~0~47~3
- 3 - O.Z. 0050/40451
polyolefins and polyurethanes.
The plastic to be stabilized is mixed with
compound (I) in a concentration of from 0.01 to 5% by
weight, preferably from 0.02 to 2~ by weight, before,
S during or after polymer formation.
The mixture of the compound (I) according to the
present invention and the plastic to be stabilized can be
prepared by any known method for mixing stabilizers or
other additives into polymers.
Besides the compound tI) according to the pres~nt
invention the stabilized plastic may al~o contain other
additives, for example antioxidants, additional light
stabilizers, metal deactivators, antistats, flame retar-
dants and also pigments and filler~.
Antioxidants and liqht stabilizers which may be
added to the plastic a~ well a~ the compound according to
the present invention are for example compounds based on
~terically hindered phenols and sulfur- andJor phos-
phorus-containing costabilizers.
Such phenolic antioxidants are for example 2,6-
di-tert.-butyl-4-methylphenol, n-octadecyl ~-(3,5-di-
tert.-butyl-4-hydroxyph~nyl)propionata, 1,1,3-tris(2-
methyl-4-hydroxy-5-tert.-butylphenyl)butane, 1,3,5-
trimethyl-2,4,6-tri~(3,5-di-tert.-butyl-4-hydroxy-
benzyl)benzene, 1,3,5-tris(3,5-di-tert.-butyl-4-hydroxy-
ben~yl) isocyanurate, 1,3,5-tris[~-(3,5-di-tert.-butyl-
4-hydroxyphenyl)pxopionyloxyethyl~ i~ocyanurate, 1,3,5-
tris~2,6-dimethyl-3-hydroxy-4-tert.-butylben~yl~ i~o-
cyanurate and pentaerythritol tetrakis~-(3,5-di-tert.-
buty~-4-hydroxyphenyl)propionats].
Suitable phosphoru~-containing antioxidant~ are
for example tris(nonylphenyl) pho~phite, distearyl
pentaerythritol dipho~phite, tri~(2,4-di-tert.-butyl-
phenyl) phosphite, tri~(2-tert.-butyl-4-methylphenyl)
phosphite, bis(2,4-di-tert.-butylphenyl) pentae L y~hritol
diphosphite and tetrakis(2,4-di-tert.-butylphenyl) 4,4'-
biphenylene dipho~phite.
47~3
- 4 - O.Z. 0050/40451
Suitable sulfur-containing antioxidants are for
example dilauryl thiodipropionate, dimyristyl thiodiprop-
ionate, distearyl thiodipropionate, pentaerythritol
tetrakis(~-laurylthiopropionate) and pentaerythritol
tetrakis(~-hexylthiopropionate).
Further antioxidants and light stabilizers which
may be used together with the compound according to the
present invention are for example 2-(2'-hydroxyphenyl)-
benzotriazoles, 2-hydroxybenzophenone, phenyl esters of
hydroxybenzoic acids, ~-cyanocinnamic acid derivatives,
nickel compounds, benzimidazolecarboxanilides and/or
oxalodianilide~.
Suitable organic polymers for stabilization by
the compound according to the present invention are for
example:
polymers of mono- and diolefins, such as low and
high density polyethy.ene, linear low density polyethyl-
ene, polypropylene, polyisobutylene, poly-1-butene,
polyisoprene, polybutadiene and copolymer~ of mono- and
diolefins and mixtures thereof;
copolymers of mono- and diolefins with other
vinyl monomer~, eg. ethylene/alkyl acrylate copolymers,
ethylene/alkyl methacrylate copolymers, ethylene/vinyl
acetate copolymers or ethylene/acrylic acid copolymers;
polystyrene;
copolymer~ of ~tyrene or ~-methyl~tyrene with
diene~ or acryloyl derivative3, ~uch as styrene-buta-
diene, ~tyrenQ-acrylonitrile, styrene/ethyl methacrylate,
styrene/butadiene/ethyl acrylate, styrene-acrylonitrile-
meth~crylate;
~BS, NBS or similar polymers;
halogen-containing polymers, eg. polyvinyl
chloride, polyvinyl fluoride, polyvinylidene fluoride and
copolymers thereof;
polymers derived from ~,~-un~aturated acids or
dQrivativQs thereof, such as polyacrylate~ and polymeth-
acrylates, polyacrylamides and polyacryloni~rile~;
)47~3
- 5 - O.Z. 0050/40451
polymers derived from unsaturated alcohol and
amines and acryloyl derivatives or acetal~ thereof, such
as polyvinyl alcohol or polyvinyl acetate;
polyurethanes, polyamides, polyureas, polyesters,
polycarbonates, polysulfones, polyether sulfones and
polyether ketones.
Further organic polymers which can be stabilized
with the compound according to the present invention are
industrial coatings, especially the two-coat automotive
baking finishes. Here too the abovementioned further
antioxidants and light stabilizers may be included as
well.
Particular preference is given to u~ing the
compound according to the present invention in polyure-
thanes, and especially in polyurethanes having polyether-
018 as polyol component.
In polyurethanes, it i8 advantageous to use a
combination of
a) the compound according to the present invention and
one or more component~ from the group3 con~isting of
b) the W absorberY and/or
c) antioxidants of the classe~ of the sterically
hindered phenols, the phosphites or of vitamin E and
derivatives thereof.
Besides the sterically hindered zmine (I) the
stabilizer combLnation may also contain other sterically
hindered amines in minor amounts.
Sterically hindered amines which may additionally
be included are for example :
bis(~,-2,2,6,6-pentamethylpiperidyl) es~er~ ~uch as bis-
(2,2,6,6-tetramethylpiperidyl) sebacata, bis~1,2,2,6,6-
pentamethylpiperidyl) sebacate, the condensation product
of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine
and succinic acid, the condensation product of N,N'-
(2,2,6,6-tetramethylpiperidyl)hexamethylenediaminQand4-
tert.-octylamino-2,6-dichloro-1,3,5-s-triazine, tris-
(2,2,6,6-tetramethylpiperidyl) nitrilotriacetate, tetra-
~30~7~3
- 6 - O.~. 0050/40451
kis(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetra-
carboxylate and 1,1'-(1,2-ethanediyl)bist3,3,5,5-tetra-
methylpiperazinone).
A suitable component ~b) W absorber can be
selected, for example from the classes of the benzotri-
azoles, the formamidines and N-cyanoethyleneindoline.
Specific examples of (b) are the 5'-methyl,
3',5'-di-tert.-butyl, 5'-tert.-butyl, 5'-(1,1,3,3-tetra-
methylbutyl),5-chloro-3',5'-di-tert.-butyl,5-chloro-3'-
tert.-butyl-5'-methyl,3'-sec.-butyl-5'-butyl,4'-octoxy,
3~,5'-di-tert.-amyl and/or 3',5'-bis(~,~-dimethylbenzyl)
derivative of 2-(2'-hydroxyphenyl)benzotriaz-le.
A suitable indoline compound is for example
~ IN
CH=C-COOCH3
Suitable representatives of the class of the
formamidines are for example the compound~ of the for-
mulae
~ --- O ~ , ." ..,..,~,
H 3C 2--C~H~ _
CH3
and
2 0 H 3C 2--C~:I~
Cl~ 2CH 3
Suitable antioxidants (component (c)) are for
examples
cl~ Phenolic antioxidants:
c1.1) alkylated monophenols eg. 2,6-di-tert.-
butyl-4-methylphenol, 2-tert.-butyl-4,6-
dimethylphenol, 2,6-di-tsrt.-butyl-4-ethyl-
phenol, 2,6-di-tert.-butyl-4-n-butylphenol,
2,6-di-tert.-butyl-4-i-bu~ylphenol, 2,6-di-
cyclopentyl-4-methylphenol, 2-(~-methyl-
47~;~
- 7 - O.Z. 0050/40451
cyclohexyl)-4,6-dimethylphenol, 2,6-di-
octadecyl-4-methylphenol, 2,4,6-tricyclo-
hexylphenol and 2,6-di-tert.-butyl-4-meth-
oxymethylphenol.
c1.2) Alkylated hydroquinone~, eg. 2,6-di-tert.-
butyl-4-methoxyphenol, 2,5-di-tert.-butyl-
hydroquinone, 2,5-di-tert.-amylhydroquinone
and 2,6-diphenyl-4~octadecyloxyphenol.
c1.3) Hydroxylated thiodiphenyl ethers, eg. 2,2~-
thio-bis(tert.-butyl-4-methylphenol), 2,2'-
thio-bis(4-octylphenol), 4,4'-thio-bis(6-
tert.-butyl-3-methylphenol~ and 4,4'-thio-
bis(6-tert.-butyl-2-methylphenol).
c1.4) Alkylidene-bisphenols, eg. 2,2'-methylene-
bis(6-tert.-butyl-4-methylphenol), 2,2'-
methylene-bic(6-tert.wbutyl-4-ethylphenol),
2,2'-methylene-bis(~4-methyl-6-8~-methyl-
cyclohexyl3-phenol], 2,2'-methylene-bi~((4-
methyl-6-cyclohaxyl)-phenol), 2,2'-methyl-
ene-bi~(6-nonyl-4-methylphenol), 2,2'-
methylene-bis(4,6-di tert.-butylphenol)~
2,2'-ethylidene-bis(4,6-di-tert.-butyl-
phenol), 2,2'-ethylidene-bis(6-tert.-butyl-
4-isobutylphenol), 2,2'-methylene-bis[6(~-
methylbenzyl)-4-nonylphenol], 2,2'-methyl-
ene-bis[6-( 3, ~-dimethylbenzyl)-4-nonyl-
phanol], 4,4'-methylene-bis-(2,6-di-tert.-
butylphenol), 4,4'-methylene-bis(6-tert.-
butyl-2-methylphenol), l,l-bis-~5-tert.-
- - butyl-4-hydroxy-2-methylphenyl)-butane, 2,6-
di-(3-tert.-butyl-5-m~thyl-2-hydroxybenzyl)-
4-methylphenol, 1,1,3-tris(5-tert.-butyl-4-
; hydroxy-2-methylphenyl)-butane, 1,1-bi~(5-
tert.-butyl-4-hydroxy-2-methylphenyl)-3-n-
dodecylmercaptobutane, ethylene glycol bis-
~3,3-bis(3'-tert.-butyl-4'-hydroxyphenyl)-
butyTate]~ di(3-tert.-butyl-4-hydroxy-5-
7~3
- 8 - O.Z. OOS0/40451
methylphenyl)-dicyclopentadiene and bis[2-
(3'-tert.-butyl-2'-hydroxy-5'-methylbenzyl)-
6-tert.-butyl-4-methylphenyl] terephthalate.
c1.5) Benzyl compounds, eg. 1,3,5-tris(3,5-di-
tert.-butyl-4-hydroxybenzyl)-2,4,6-tri-
methylbenzene, di-(3,5-di-tert.-butyl-4-
hydroxybenzyl) sulfide, isooctyl 3,5-di-
tert.-butyl-4-hydroxybenzyl-mercaptoacetate,
bis~4-tert.-bu~yl-3-hydroxy-2,6-dimethyl-
benzyl)dithioterephthalate,1,3,5-tri~(3,5-
di-tert.-butyl-4-hydroxybenzyl) isocyanur-
ate, 1,3,5-tris(4-tert.-butyl-3-hydroxy-2,6-
dimethylbenzyl) isocyanurate, dioctadecyl
3,5-di-tert.-butyl-4-hydroxybenzylphosphon-
ate and calcium monoethyl 3,5-di-tert.-
butyl-4-hydroxybenzylphosphonate.
c1.6) Acylaminophenols,eg.4-hydroxylauro~nilide,
4-hydroxystearanilide, 2,4-bi~-octylmer-
capto-6-(3,5-di-tert.-butyl-4-hydroxyani-
lino)-s-tria~ine and octyl N-(3,5-di-tert.-
butyl-4-hydroxyphenyl)carbamate.
cl.7) E~ters of ~-(3,5-di-tert.-butyl-4-hydroxy-
phenyl)propionic acid with monohydric or
polyhydric alcohol~, eg. with methanol,
octadecanol, 1,6-hexanediol, neopentyl-
glycol, thiodiethylene glycol, diethylene
glycol, triethylene glycol, pentaerythritol,
tris-hydroxyethyl isocyanurate and di-
hydroxyethyl oxamide.
- -cl-.8) E~texs of ~-(5-tert.-butyl-4-hydroxy-3-
methylphenyl)propionlc acid with monohydric
or polyhydric alcohols, eg. with methanol,
octadecanol, 1,6-hexanediol, neopentyl-
glycol, thiodiethylene glycol, diethylene
glycol, triethylene glycol, pantaerythritol,
tris-hydroxyethyl isocyanurats and di-
hydroxyethyl oxamide.
7 ~ ~
- 9 - o.Z. 0050/40451
c1.9) Amides of ~-(3,5-di-tert.-butyl-4-hydroxy-
phenyl)propionic acid, eg. N,N'-di~3,5-di-
tert.-butyl-4-hydroxyphenylpropionyl)-
hexamethylenediamine, N,N'-di(3,5-di-tert.-
butyl-4-hydroxyphenylpropionyl)trimethylene-
diamine and N,N'-di(3,5-di-tert.-butyl-4-
hydroxyphenylpropionyl)hydrazine.
c2) Phosphorus-containing antioxidants, eg. triphenyl
phosphite, diphenyl alkyl phosphite3, phenyl dialkyl
phosphites, tri(nonylphenyl) phoRphite, trilauryl
phosphite, trioctadecyl phosphite, distearyl
pentaerythritol diphosphite, tri~(2,4-di-tert.-
butylphenyl) pho~phite, diisodecyl pentaerythritol
diphosphite, di(2,4-di-tert.-butylphenyl) penta-
erythritol diphoRphite, tri~tearyl ~orbitol triphos-
phite, tetraki~(2,4-di-tert.-butylphenyl) 4,4'-
biphenylene dipho~phonite and 3,9-bi~(2,4-di-tert.-
butylphenoxy)-2,4,8,10-tetraoxa-3,9-dipho~pha~piro-
[5.5]undecane.
c3) Vitamin E and derivatives thereof, eg. derivatives
of 6-hydroxy-2,5,7,8-tetramethylchroman, such as ~-
tocopherol, 6-hydroxy-2,5,7,8-tetramethylchroman-2-
ylethyl ~tearate, vitamin-E acetate and vitamin-~
propionate.
It i~ al~o possible to uqe as (c3 in the mixtures
according to the pre~ent invention mixture~ of similar
and differant antioxidants, for examplo mixtures of ~-
tocopherol and tri~nonylphenyl~ phosphite in a weight
ratio of from 1~10 to 10:1.
- - Preferred W absorber~ (b~ come from the cla~s
of the 2-~2'-hydroxyphenyl)benzotriazole3 and of N-
cyanoethyleneindoline. Particular preference for use as
(b) is given to the 5'-methyl, the 3',5'-di-tort.-butyl,
the S'-tert.-butyl, the 3',5'-di-tert.-amyl, the 5-
chloro-3',5'-ditert.-butyl and the 3',5'-bis(~,~-dime-
thylbenzyl) derivativ~ of 2-(2'-hydroxyphenyl~bsnzotria-
zole, the compound of the formula
7~3
- 10 - O.Z. 0050/40451
~CH3
CH= I--COOCH 3
CN
and a mixture of compounds of the formulae
( C~ 2 ) 2COO [CH 2CH 2~3n H
and
S ~
(CH2) 2COO[cH2cH2~}2
where n i~ such that the average molecular weight of the
mixture i~ approximately 600 - 1900.
Preferred antioxidant~ are 2,6-di-tert.-butyl-4-
methylphenol,2-tert.-butyl-4,6-dimethylphenol,triethyl-
eneglycolbi~-3-(3-tert.-butyl-4-hydroxy-5-methylphenyl)
propionate, pentaerythritol tetra-3-(3-tert.-butyl-4-
hydroxy-5-methylphenyl) propionate, ~-tocopherol, 6-
hydroxy-2,5,7,8-tetramethylchroman-2-ylethyl stearate,
tri(nonylphenyl) pho~phite and tetra-bi~(2,4-di-tert.-
butylphenyl) 4,4'-biphenylene diphosphonite.
Pref~rence i8 further given to a mixture of ~-
tocopherol and tri(nonylphenyl) phosphite in a weight
ratio of from 1:10 to lOsl, in particular 1:10.
- The component3 (a), (b) and (c) of the stabilizer
mixture according to the present invention csn be mixed
into the pol~urethane individually a~ such or a~ a
mixture, each in amount~ of from 0.01 to 5, preferably
from 0.05 to 2.5, in particular from 0.1 to 2, % by
weight, based on the material to be ~tabilized.
The stabilizer mixture i3 usually added by
di~olving the individual components or the mi~ture of
~)47~3
- 11 - O.Z. 0050/40451
(a), (b) and/or (c) in the polyol component of the
polyurethane, if necessary by gentle heating. However,
the mixture according to the present invention can also
be introduced by mixing the individual compounds or the
ready-prepared mixture into the melt in a conventional
manner before or during shaping. However, the stabilizer
may also be incorporated by applying the dissolved or
dispersed compounds (a), (b) and/or (c) to the polymer or
by mixing them into a solution, suspension or emulsion of
the polymer, if necessary by subsequent evaporation of
the solvent.
The following Examples will illustrate and
explain the invention in more detail:
PREPARATION EXAMPLE
A solution of 2-ethylhexanoyl chloride in 200 ml
of dichloromethane was added dropwise at room temperature
to a solution of 139.9 g of 2,2,6,6-tetramethyl-4-
hydroxypiperidine in 800 ml of dichloromethane. After 3
hours of stirring at room temperature, the precipitated
2,2,6,6-tetramethyl-4-hydroxypiperidinehydrochloridewas
filtered off, the dichloromethane phase was concentrated,
and the residue was distilled under an oil pump vacuum.
Thi~ gave 126 g of the compound of the formula
H3C
H 3~_o~ ( CH 2 ) 3--CH 3 ( I )
H 3C CH 2CH 3
as a colorle~ liquid of boiling point 101-C/0.2 torr.
Calculated: C 72.0 H 11.7 N 4.9 O 11.3%
Found s C 72.1 H 11.7 N 5.2 O 11.8%
USE EXAMPLE
Stabilization of polyurethanes
A) Preparation of samples for irradiation te~t
A polyol component, comprising 41.9 parts of a
polyetherol (OH number: 29.0; obtained by addition of
propylene oxide and ethylene oxide to propylen~ glycol
and having approximately 84~ of primary hydroxyl groups)~
7 ~3
- 12 - ~.Z. 0050/40451
42.5 parts of a polyetherol (OH number: 27.0; obtained by
addition of propylene oxide and ethylene oxide to tri-
methylolpropane and having approximately 88% of prLmary
hydroxyl groups), 8.1 part~ of 1,4-butanediol, 1724 parts
of a 25% strength solution of diazabicyclooctane in 1,4-
butanediol, 0.016 part of dibutyltin dilaurate, 0.1 part
of silicone stabilizer OS 710 (Bayer AG), 5.49 parts of
Frigen 11 and 0.17 part of water were admixed with the
stabilizers indicated in the table and foamed in a mixing
ratio of 100:48.5 parts with a prepolymer having an
isocyanate group content of 23.0~ at a component and mold
temperature of 25C to give test sheets.
The NCO prepolymer was prepared from 87.17 part~
of 4,4'-diphenylmethane diisocyanate and 4.83 part~ of a
polyetherol of OH number 250 (obtained by addition of
propylene oxide to propylene glycol) and 8.0 parts of
dipropylene glycol.
B) Testing of polyurethane samples
The sdmples were exposed in a Xenotest~ 450 to
determine the Yellownes~ Index per ASTM D 1925.
The stabilizer mixtures u~ed and the result~ of
the light exposure te~t are summarized in the following
table:
TABL~ 1
Stabilizer Amount Yellowness Index per
(% by weight) AST~ D 1925 in Xeno-
te~t 450 after 96 h
_
0 - 49.4
MiXtur~ of
C 1, o.5
C 2 and 0.5 15.3
C 3 0.25
Mixture of
3S C 4, 0.5
C 2 and 0.5 17.5
C 3 0.25
47~3
- 13 - O.Z. 0050/40451
C 1 = compound of preparation example
C 2 = mixture of
C~
. ~ CH 2 ) 2COO tCH 2CH 2~] ~ and
( CH 2 ) 2COO [CH 2CH 2-]--] ~ and
average molecular weight of mixture >600.
C 3 = mixture of ~-tocopherol and tri(nonylphenyl)
pho3phite (1:10 by weight~
C 4 = compound of the formula
CH3 0 CH3
H 3C ) ~ ~CH 3
H 3C--N ~C--( CH 2 J 8--C~< ~CH 3
H 3C ~ CH 3
CH3 CH3,
~ . .
