Note: Descriptions are shown in the official language in which they were submitted.
--` 1087344
This invention relates to light-stable polyolefin
compositions. More particularly, it relates to polyolefin
compositions stabilized against the deteriorative effects of
light by the incorporation therein of a light-stabilizing ~ ;
amount of a combination of (a) a 2-hydroxy-4-alkoxybenzo-
phenone or a 2-(2'-hydroxy-5'-alkylphenyl)benzotriazole, and ~ -
(b) a compound represented by the formula (I):
NO~C ORl
wherein Rl represents an alkyl or alkenyl radical having
1-20 carbon atoms; R2 represents an alkyl radical having 1-8
carbon atoms; and R3 represents an alkyl radical branched on
; the alpha carbon atom having 3-8 carbon atoms. Preferably,
Rl is alkyl of 6-20 carbon atoms and R2 and R3 are both
t-butyl.
It is well-known that sunlight and other sources
of ultraviolet radiation cause degradation of polymers as
evidenced by embrittlement or yellowing of plastic articles
made therefrom. It is also well-known that this degradation
can be inhibited by incorporating light stabilizer additives
in or on such articles.
Various additives, used alone or in combinations,
have been suggested in order to prolong the useful lives of
articles made from polyolefins. Since none has been found
; to be completely satisfactory, research continues in order
to find new compounds, or combinations of compounds, which
will be more satisfactory.
In accordance with the invention there is provided
- ` 1087344
a composition of matter stabilized against the deteriorative
effects of light comprising in combination a polyolefin, and
light-stabilizing amounts of (a) a 2-hydroxy-4-alkoxybenzo-
phenone or a 2-(2'-hydroxy-5'-alkylphenyl)benzotriazole,
wherein the aIkoxy and alkyl substituents have up to 12 car-
bon atoms, and (b) a compound represented by formula (I).
Generally, effective stabilization occurs when the
polyolefin compositions contain from about 0.1% to about
4.0% of each of the light stabilizer compounds, based on the
weight of the polyolefin.
Preferably, the compositions comprise polypropyl-
ene containing from about 0.2% to about 2.0% of each of the
light stabilizer compounds, basea on the weight of the poly-
propylene. More preferably, the compositions comprise poly-
propylene containing about 0.25% by weight of either 2-hy-
droxy-4-n-octyloxybenzophenone or 2-(2'-hydroxy-5'-t-octyl-
phenyl)benzotriazole, and 0.25% by weight of n-hexadecyl
3,5-di-t-butyl-4-hydroxybenzoate, based on the weight of the
polypropylene.
The compositions of this invention have signifi-
cantly better resistance to the deteriorative effects of
light than similar compositions comprising a polyolefin and
equal total amounts of any single one of these known light
stabilizer compounds used alone.
The compositions of this invention provide light-
stable polyolefins which are useful in films, sheets and
fibers, particularly in films and sheets.
The light stabilizer compounds may be incorporated
into or on such plastic materials by any of the various pro-
cedures known in the art for such purpose, such as by dry
- 2 -
1087344
1 blending the additive with the polyolefin in powder or gran-
ular form, followed ! byimillih~.Banbury m~xing~ mo(lding,
casting;-extrud-ing~, swe~ling,la~a the likeY~by immérsing;the
polyolefin as film, sheet, fibers,:etc. ih~a-solution of the
additive in an appropriate solvent (as ip a dyeing process),
etc.
The amounts of the light-stabilizer compounds
needed for effective stabilization of the polyolefin against
degradation will depend on the nature of the polyolefin and
the amount of exposure to ultraviolet light to which the art-
icle will be subjected.
The esters of formula (I) may be prepared by the
reaction of a suitable 3,5-dialkyl-4-hydroxybenzoic acid
with an appropriate alcohol in the presence of a catalyst
such as sulfuric acid. They may also be prepared by react-
ing the appropriate alcohol with a suitable 3,5-dialkyl-4-
-hydroxybenzoyl chloride.
The preparation of many compounds of formula (I)
can be found in the literature. For example, Dexter et al.,
in Examples 1-3 of United States Patent 3,681,431, describe
the preparations of the n-octadecyl, n-hexyl and n-dodecyl
esters of 3,5-di-t-butyl-4-hydroxybenzoic acid.
Suitable compounds within the scope of formula (I)
include the following: n-octadecyl 3,5-di-t-butyl-4-hydroxy-
benzoate, n-hexadecyl 3,5-di-t-butyl-4-hydroxybenzoate, n-octa-
decyl 3,5-diisopropyl-4-hydroxybenzoate, isobutyl 3,5-di-t-
-octyl-4-hydroxybenzoate, methyl 3-methyl-5-isopropyl-4-hy-
droxybenzoate, cyclohexyl 3,5-di-t-amyl-4-hydroxybenzoate,
allyl 3,5-di-t-butyl-4-hydroxybenzoate, 2-butenyl 3,5-di-
isopropyl-4-hydroxybenzoate and n-octadecyl 3-n-octyl-5-t-
- 3 -
~1187344
. .
1 -butyl-4-hydroxybenzoate.
Suitable light stabilizers of the 2-hydroxy-4-
-alkoxybenzophenone class include the following: 2-hydroxy-
-4-n-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone,
2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-n-butoxy-
benzophenone, 2,2'-dihydroxy-4-n-octyloxybenzophenone, 2,2'-
-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-n-decyl-
oxybenzophenone, 2,2'-dihydroxy-4,4'-di-n-(octyloxy)benzo-
phenone, 2,2'-dihydroxy-4-i-butoxybenzophenone, 2,2'-dihydroxy-
-4-methoxybenzophenone and 2-hydroxy-4-isooctyloxybenzophen-
one.
Suitable light stabilizers of the 2-(2'-hydroxy-
-5'-alkylphenyl)benzotriazole class include the following:
2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-(2'-hydroxy-
-5'-methylphenyl)-benzotriazole, 2-(2'-hydroxy-5'-t-butyl-
phenyl)-benzotriazole, 2-(2'-hydroxy-5'-amylphenyl)-benzo-
- triazole, 2-(2'-hydroxy-3',5'-dimethylphenyl)-benzotriazole,
2-(2'-hydroxy-5'-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-
-hydroxy-5'-t-octylphenyl)-5-methoxybenzotriazole, 2-(2'-
20 -hydroxy-5'-t-octylphenyl)-5-methylbenzotriazole, 2-(2'-hy- -~
droxy-5'-dodecylphenyl)-benzotriazole, 2-(2'-hydroxy-3'-t-
-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and 2-(2'-
-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole.
The combination of light-stabilizing compounds of
this invention is useful for protecting organic polymeric
materials normally subject to deterioration by ultraviolet
light, particularly polyolefins. As used herein, the term
polyolefins includes homopolymers such as low density poly-
ethylene, high density polyethylene, polypropylene, polysty-
rene, polybutadiene, polybutylene, polyisoprene, and the
1087344
1 like, and copolymers such as ethylene-propylene copolymer,
ethylene-butylene copolymer, ethylene-vinyl acetate copoly-
mer, styrene-butadiene copolymer, acrylonitrile-styrene-buta-
diene copolymer, and the like.
The aforementioned combination of light-stabilizing
compounds may also be used in combination with other addi-
tives such as antioxidants, fillers, pigments, dyes, anti-
static agents, and the like.
The following examples, in which parts and percent-
ages are by weight unless otherwise stated, are presented
to further illustrate the present invention.
Examples 1 - 6
General Procedure
Unstabilized polypropylene (100 parts) was dry
blended with 2,6-di-t-butyl-4-methylphenol (0.05 part), octa-
decyl 3,5-di-t-butyl-4-hydroxyhydrocinnamate (0.05 part),
calcium stearate (0.10 part) and a stabilizer additive (0.50
part), or a combination of two stabilizer additives (0.25
part each), under test. The blended composition was extruded
at a maximum temperature of 440F., and pelletized. The pel-
lets were then extruded into monofilaments at a maximum temp-
erature of 485F. with a draw ratio of 7 to 1. After expos-
ure to a xenon arc in a Weather-Ometer for various periods
of time, the monofilaments were tested for breaking strength
and the results obtained were converted into percent of the
original strength of the filament.
The following results were obtained with light-
stabilizer compounds and combinations of light-stabilizer
compounds, following the procedure described above. The
table shows (Examples 1-4) the results obtained using 0.5
_ 5 _
1~87344
1 part of each of the light-stabilizer compounds alone. Also
included are results obtained with combinations of the 2-hy-
droxy-4-alkoxybenzophenone of the 2-(2'-hydroxy-5'-alkoxy-
phenyl)benzotriazole with the aromatic 3,5-di-alkyl-4-hydroxy-
benzoate (Examples 5-6, illustrative of the prior art) or
with the alkyl 3,5-di-alkyl-4-hydroxybenzoate (Examples 7-8,
illustrative of the present invention).
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-- 6 --
1~7344
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-- 7 --
1~7344
1 These results show that the combinations of stab-
ilizer additives of this invention provide a significant
improvement in light stabilization of polypropylene.
In the manner described above, substituting 0.25
part of n-octadecyl 3,5-diisopropyl-4-hydroxybenzoate, iso-
butyl 3,5-di-t-octyl-4-hydroxybenzoate, methyl 3-methyl-5-
-isopropyl-4-hydroxybenzoate, cyclohexyl 3,5-di-t-amyl-4-hy-
droxybenzoate, allyl 3,5-di-t-butyl-4-hydroxybenzoate, n-octa- ;
decyl 3,5-di-t-butyl-4-hydroxybenzoate, or n-dodecyl 3,5-
-di-t-butyl-4-hydroxybenzoate for the additive of Example 4,
similar results are obtained.
In the manner described in Example 7, substituting -;
0.1-4.0 parts of 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-
-4-dodecyloxybenzophenone, 2-hydroxy-4-n-butoxybenzophenone,
2,2'-dihydroxy-4-n-octyloxybenzophenone, 2,2'-dihydroxy-4,4'- -;
-dimethoxybenzophenone, 2,2'-4,4'-n-octyloxybenzophenone,
2,2'-dihydroxy-4-i-butoxybenzophenone or 2,2'-dihydroxy-4-
-methoxybenzophenone for the 2-hydroxy-4-n-octyloxybenzophen-
one, similar results are obtained.
In the manner described in Example 8, substituting
0.1-4.0 parts of 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole,
2-(2'-hydroxy-5'-t-butylphenyl)-benzotriazole, 2-(2'-hy-
droxy-5'-amylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-
methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)-
-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)-5-
-methoxybenzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)-5-
-methylbenzotriazole, 2-(2'-hydroxy-5'-n-dodecylphenyl)-
benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-
-chlorobenzotriazole, or 2-(2'-hydroxy-3',5'-di-t-butyl-
phenyl)-5-chlorobenzotriazole for 2-(2'-hydroxy-5'-t-octyl-
.. , . :. ,
7344
1 phenyl)benzotriazole, similar results are obtained.
Example 9
In the manner described in Examples 7-8 utilizing
0.125 part each of the light stabilizers of Examples l and
2 and 0.25 part of the ester of Example 4, per hundred parts
of polypropylene, similar results are obtained.
- Examples 10 - 11
In the manner described in Examples 7-8, substi-
tuting a high impact ethylene-butylene copolymer for the
polypropylene, similar results are obtained.
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