Process for stabilization of polyolefins in permanent...

Details Process for stabilization of polyolefins in permanent... Process for stabilization of polyolefins in permanent...

1996-09-09

2003-04-01

Szekely, Peter (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S099000, C524S117000, C524S119000, C524S126000, C524S127000, C524S151000, C524S153000, C524S194000, C524S350000

Reexamination Certificate

active

06541547

ABSTRACT:

The present invention relates to compositions comprising a polyolefin which is in permanent contact with extracting media, and stabilizer mixtures, to the use thereof for stabilizing thick-layer polyolefin mouldings, and to a process for stabilizing thick-layer polyolefin mouldings.
R. Gächter and H. Müller, “Plastics Additives Handbook, 3rd Edition”, pages 1 to 100 (1990), discloses, for example, that polyolefins can be protected against oxidative damage during preparation, processing and use by means of suitable stabilizer mixtures. In many cases, the stabilized polyolefin mouldings are in contact with liquid or gaseous media during use. It is therefore necessary that the stabilizer mixtures added to the polyolefin moulding have adequate chemical resistance to the particular contact media. Examples of polyolefin mouldings which are particularly at risk are pipes, undersea cables, tanks and geo-membranes which are in permanent contact with extracting media.
EP-A-0 324 106 describes a polyolefin moulding composition which has particularly good stability in permanent contact with extracting media. The stabilizer mixture used is a symmetrical triaryl phosphite and an ester of 3,3-bis(3′-tert-butyl-4′-hydroxyphenyl)butanoic acid.
It has now been found that a selected mixture comprising an organic phosphite or phosphonite and a specially selected group of sterically hindered phenols or a certain group of sterically hindered amines are particularly suitable as stabilizers for polyolefin mouldings which are in permanent contact with extracting media. It has also been found that a three-component mixture comprising a phosphite or phosphonite, a phenolic antioxidant and a certain group of sterically hindered amines is particularly suitable as stabilizer for polyolefin mouldings which are in permanent contact with extracting media.
The present invention therefore relates to compositions comprising
a) a polyolefin which is in permanent contact with extracting media,
b) at least one compound from the group consisting of organic phosphites or phosphonites,
c) (i) at least one compound of the formula I or II
 in which
n is the number 1 or 3,
R
1
is C
1
-C
18
alkyl, C
5
-C
12
cycloalkyl, phenyl or C
7
-C
9
phenylalkyl,
R
2
is hydrogen, C
1
-C
18
alkyl, C
5
-C
12
cycloalkyl, phenyl or C
7
-C
9
phenylalkyl,
R
3
is hydrogen or methyl,
if n is 1,
R
4
is hydrogen, C
1
-C
4
alkyl or
if n is 3,
R
5
is hydrogen or methyl,
R
6
is hydrogen, C
1
-C
20
alkyl, unsubstituted or C
1
-C
4
alkyl-substituted phenyl or naphthyl; or
M
r
+
r
,
R
7
is C
1
-C
20
alkyl, unsubstituted or C
1
-C
4
alkyl-substituted phenyl or naphthyl,
M
r+
is an r-valent metal cation, and
r is 1, 2 or 3; or
(ii) at least one compound from the group consisting of sterically hindered amines having a molecular weight of greater than 500 and containing at least one radical of the formula III or IV
 in which
G is hydrogen or methyl,
G
1
and G
2
are hydrogen, methyl or together are ═O; or
(iii) (x) at least one compound from the group consisting of phenolic antioxidants, and (y) at least one compound from the group consisting of sterically hindered amines having a molecular weight of greater than 500 and containing at least one radical of the formula III or IV.
Alkyl having up to 20 carbon atoms is a branched or unbranched radical, for example methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, 2-ethylbutyl, n-pentyl, isopentyl, 1-methylpentyl, 1,3-dimethylbutyl, n-hexyl, 1-methylhexyl, 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-methylundecyl, dodecyl, 1,1,3,3,5,5-hexamethylhexyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, eicosyl or docosyl. R
1
and R
2
are preferably C
1
-C
12
alkyl, in particular C
1
-C
8
alkyl, for example tert-butyl. R
7
is particularly preferably C
1
-C
12
alkyl, in particular C
1
-C
10
alkyl, for example C
1
-C
8
alkyl.
C
5
-C
12
cycloalkyl, in particular C
5
-C
8
cycloalkyl, is, for example, cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl. Cyclohexyl is preferred.
C
7
-C
9
phenylalkyl is, for example, benzyl, &agr;-methylbenzyl, &agr;,&agr;-dimethylbenzyl or 2-phenylethyl.
C
1
-C
4
alkyl-substituted phenyl or naphthyl, which preferably contains 1 to 3, in particular 1 or 2, alkyl groups, is, for example, o-, m- or p-methylphenyl, 2,3-dimethylphenyl, 2,4-di-methylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-di-methylphenyl, 2-methyl-6-ethylphenyl, 4-tert-butylphenyl, 2-ethylphenyl, 2,6-diethyl-phenyl, 1-methylnaphthyl, 2-methylnaphthyl, 4-methylnaphthyl, 1,6-dimethylnaphthyl or 4-tert-butylnaphthyl.
A monovalent, divalent or trivalent metal cation is preferably a cation of an alkali metal, alkaline earth metal, heavy metal or aluminium, for example Na
+
, K
+
, Mg
++
, Ca
++
, Ba
++
, Zn
++
or Al
+++
. Ca
++
is particularly preferred.
Of interest are compositions in which component (b) is an organic phosphite or phosphonite of the formula (1) to (7)
in which the indices are integers and
n′ is 2, 3 or 4; p is 1 or 2; q is 2 or 3; r is 4 to 12; y is 1, 2 or 3; and z is 1 to 6;
A′, if n′ is 2, is alkylene having 2 to 18 carbon atoms; alkylene having 2 to 12 carbon atoms which is interrupted by —S—, —O— or —NR′
4
—; a radical of the formula
A′, if n′ is 3, is a radical of the formula —C
r
H
2r−1
—;
A′, if n′ is 4, is the radical of the formula C(CH
2
&Parenclosest;
4
;
A″ is as defined for A′ if n′ is 2;
B′ is a radical of the formula —CH
2
—; —CHR′
4
—; —CR′
1
R′
4
—; —S—or a direct bond; or C
5
-C
7
cycloalkylidene; or cyclohexylidene which is substituted by 1 to 4 C
1
-C
4
alkyl radicals in position 3, 4 and/or 5;
D′, if p is 1, is methyl and, if p is 2, is —CH
2
OCH
2
—;
E′, if y is 1, is alkyl having 1 to 18 carbon atoms, a radical of the formula —OR′
1
or halogen;
E′, if y is 2, is a radical of the formula —O—A″—O—;
E′, if y is 3, is a radical of the formula R′
4
C(CH
2
O&Parenclosest;
3
;
Q′ is the radical of an at least z-valent alcohol or phenol, this radical being bonded to the P atom(s) via the alcoholic or phenolic O atom(s);
R′
1
, R′
2
and R′
3
, independently of one another, are alkyl having 1 to 30 carbon atoms; alkyl having 1 to 18 carbon atoms which is substituted by halogen, —COOR′
4
, —CN or —CONR′
4
R′
4
; alkyl having 2 to 18 carbon atoms which is interrupted by —S—, —O— or —NR′
4
—; phenyl-C
1
-C
4
—alkyl; cycloalkyl having 5 to 12 carbon atoms; phenyl or naphthyl; phenyl or naphthyl which is substituted by halogen, 1 to 3 alkyl radicals or alkoxy radicals having a total of 1 to 18 carbon atoms or phenyl-C
1
-C
4
alkyl; or a radical of the formula
in which m is an integer in the range from 3 to 6;
each R′
4
, independently of the others, is hydrogen; alkyl having 1 to 18 carbon atoms, cycloalkyl having 5 to 12 carbon atoms; or phenylalkyl having 1 to 4 carbon atoms in the alkyl moiety;
R′
5
and R′
6
, independently of one another, are hydrogen; alkyl having 1 to 8 carbon atoms or cycloalkyl having 5 or 6 carbon atoms;
R′
7
and R′
8
, in the case where q=2, are, independently of one another, C
1
-C
4
alkyl or together are a 2,3-dehydropentamethylene radical; and
R′
7
and R′
8
, in the case where q=3, are methyl;
the substituents R′
14
, independently of one another, are hydrogen; alkyl having 1 to 9 carbon atoms or cyclohexyl;
the substituents R′
15
, independently of one another, are hydrogen or methyl; and
R′
16
is hydrogen or C
1
-C
4
alkyl, and in the case where a plurality of radicals R′
16
are present, the radicals R′
16
are identical or different;
X′ and Y′ are each a

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