Use of sterically hindered amines or stabilised ethylene...

Details Use of sterically hindered amines or stabilised ethylene... Use of sterically hindered amines or stabilised ethylene...

2000-06-08

2003-04-15

Sanders, Kriellion A. (Department: 1714)

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

Synthetic resins

Processes of preparing a desired or intentional composition...

C524S099000, C523S100000

Reexamination Certificate

active

06548580

ABSTRACT:

The present invention relates to the use of ethylene homo- and copolymers stabilized by sterically hindered amines or their N-hydroxy or N-oxyl derivatives to produce articles of plastic and components for the storage and transport of vegetable oil esters.
The invention also relates to articles of plastic and components for the transport and storage of vegetable oil esters, which are produced using such stabilized polymers, and to ethylene homo- and copolymers stabilized by adding derivatives of quinoline or of diphenylamine.
In automotive fuel systems there is increasing use of plastic fuel tanks (PFTs) of polyethylene for spark-ignition and diesel-engined vehicles. For diesel-operated vehicles in particular the biodiesel fuels based on renewable raw materials are increasing in importance. The principal biodiesel fuels are based on vegetable oil methyl esters (VMEs), of which rapeseed oil methyl ester (RME) is the major representative. As the biodiesel fuels become more important, so will their storage and transport in containers or pipes made of polyethylene.
RME proves to be aggressive to many of the plastics used in the fuel system of a motor vehicle. Even high molecular mass polyethylene, as is used to produce PFTs and other hollow articles, may be attacked by RME, especially at elevated temperature. Its effect is to accelerate the embrittlement of the material, thereby impairing its long-term service properties.
Coating the interior of the hollow articles has been proposed for overcoming this problem. One disadvantage of an interior coating, however, is that it is highly complex to implement industrially and so always gives rise to considerable additional manufacturing costs. Moreover, in the PFT sector there is increasing use of co-extruded 6-layer tanks with a central barrier layer, whose additional internal fluorination would weigh heavily on the manufacturing costs of such PFTs.
It is an object of the present invention to provide ethylene homo- and copolymers, for producing articles of plastic and components for the storage and transport of vegetable oil esters, which are stabilized against the effect of vegetable oil esters.
We have found that this object is achieved by the use of ethylene homo- and copolymers stabilized by sterically hindered amines or by N-hydroxy or N-oxyl derivatives for producing articles of plastic and components for the storage and transport of vegetable oil esters.
We have also found articles of plastic and components for the transport and storage of vegetable oil esters, produced using such stabilized polymers, and ethylene homo- and copolymers stabilized by adding derivatives of quinoline or of diphenylamine.
Suitable stabilizers for the ethylene homo- and copolymers are N-hydroxy and N-oxyl derivatives of sterically hindered amines, but preferably the sterically hindered amines themselves.
By sterically hindered amines are meant all secondary amines whose substitution on the carbons adjacent to the amine nitrogen is such that no single hydrogen remains at these positions. Preference is given to derivatives of 2,2,6,6-tetramethylpiperidine, substituted either at the 4-position or on the amine nitrogen, and to derivatives of quinoline and of diphenylamine.
Examples of suitable amines are the following structures
where the Rs are identical or different alkyls, cycloalkyls, aralkyls or aryls, alone or joined in pairs to form a ring system, and Y is a group required to complete a 5- or 6-membered ring. Examples of R are C
1
-C
20
-alkyl, especially C
1
-C
8
-alkyl, C
5
- or C
6
-cycloalkyl, benzyl or phenyl. Examples of Y are the alkylene groups —(CH
2
)
2
— and —(CH
2
)
3
—.
Also suitable are the following structures
where the aromatic rings may each carry 1 to 3 inert substituents such as C
1
-C
4
-alkyl, C
1
-C
4
-alkoxy or cyano, for example.
It is preferred to employ sterically hindered amine derivatives of cyclic amines, such as of piperidine or pyrrolidine compounds, whose ring may contain a further heteroatom such as nitrogen, oxygen or sulfur which is not adjacent to the hindered amine nitrogen. The steric hindrance is provided by substituents in both positions adjacent to the amine nitrogen, suitable substituents being hydrocarbon radicals which replace all 4 hydrogens of the &agr;-CH
2
-groups. Examples of substituents are phenyl, C
3
-C
6
-cycloalkyl, benzyl and especially C
1
-C
6
-alkyls, it being possible for alkyls attached to the same &agr; carbon to be linked with one another in a 5- or 6-membered ring. The radicals set out individually under R
1
and R
2
are particularly preferred. Preference is given to using 2,2,6,6-tetraalkylpiperidine derivatives.
Preferred sterically hindered amines or their N-hydroxy or N-oxyl derivatives for use in accordance with the invention are those of the formula I
where
R
1
and R
2
are C
1
-C
4
-alkyl or phenyl or together with the carbon to which they are attached are a 5- or 6-membered saturated hydrocarbon ring,
R
3
is hydrogen, hydroxyl, amino or an m-valent, oxygen- or nitrogen-bonded organic radical or together with R
4
is oxygen or a ring structure defined under R
4
,
R
4
is hydrogen or C
1
-C
12
-alkyl or together with R
3
is oxygen or together with R
3
and the carbon to which they are attached is a ring structure
where m is 1 when R
3
and R
4
unite to form a radical,
R
5
is hydrogen, C
1
-C
12
-alkyl or —(CH
2
)
z
—COOR
6
,
R
6
is identical or different C
1
-C
18
-alkyl,
X is hydrogen, hydroxyl or oxygen,
k is 0 or 1,
z and p are from 1 to 12 and
m is from 1 to 100.
R
1
and R
2
may, for example, be the C
1
-C
4
-alkyls methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl or together may form tetra- or pentamethylene. R
1
and R
2
are preferably methyl.
Examples of R
4
are hydrogen, the abovementioned C
1
-C
4
-alkyls and also pentyl, sec-pentyl, tert-pentyl, neopentyl, hexyl, 2-methylpentyl, heptyl, 2-methylhexyl, octyl, isooctyl, 2-ethylhexyl, nonyl, 2-methylnonyl, isononyl, 2-methyloctyl, decyl, isodecyl, 2-methylnonyl, undecyl, isoundecyl, dodecyl and isododecyl (isooctyl, isononyl and isodecyl are trivial names deriving from the carbonyl compounds obtained by oxo synthesis; cf. in this respect Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A1, pages 290-293, and Vol. A10, pages 284 and 285).
p is preferably 6-12, especially 9.
z is preferably 1-4, especially 2.
Examples of R
5
in addition to hydrogen are the abovementioned C
1
-C
12
-alkyls. R
5
is preferably hydrogen, C
1
-C
4
-alkyl or (CH
2
)
z
—COO(C
1
-C
6
-alkyl), and with particular preference is —CH
2
—CH
2
—COO(CH
2
)
11
—CH
3
and —CH
2
—CH
2
—COO(CH
2
)
13
—CH
3
.
Possible examples of R
6
are one of the abovementioned C
1
-C
12
-alkyls or tridecyl, isotridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl. Dodecyl and hexadecyl are preferred.
Examples of preferred radicals R
3
are the following m-valent radicals
where
R
7
is C
1
-C
12
-alkyl or —(CH
2
)
z
—COOR
6
R
8
is hydrogen or C
1
-C
18
-alkyl,
R
9
is C
1
-C
18
-alkyl, vinyl or isopropenyl,
R
10
is C
8
-C
22
-alkyl,
R
11
is hydrogen or an organic radical as is normally formed in the free-radical polymerization of the initial monomers,
k is 0 or 1,
x is from 1 to 12 and
n is an even number m.
If R
3
is one of these radicals, then R
4
is preferably hydrogen. The variable m can be from 1 to 100, and is preferably 1,2,3,4 or a number from 10 to 50, with mixtures generally being employed especially in the case of the oligomeric or polymeric radicals R
3
.
It has been found that oligomeric and polymeric amine derivatives where m≧2 have a particularly good stabilizing action. Preference is also given to those amine derivatives comprising no hydrolyzable groups, such as ester groups.
Suitable radicals R
7
are the same as for R
5
. R
7
is preferably C
1
-C
4
-alkyl.
In addition to hydrogen, suitable radicals R
8
are the same as for R
6
. R
8
is preferably hydrogen.
Particularly suitable radicals R
9
are vinyl, isopropenyl or C
15
-C
17
-alkyls.
Examples of suitable radic

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