U.S. patent application number 14/111938 was filed with the patent office on 2014-10-09 for polyolefin pipe with improved migration behaviour.
This patent application is currently assigned to BOREALIS AG. The applicant listed for this patent is Martin Anker, Svein Jamtvedt. Invention is credited to Martin Anker, Svein Jamtvedt.
Application Number | 20140302266 14/111938 |
Document ID | / |
Family ID | 44584791 |
Filed Date | 2014-10-09 |
United States Patent
Application |
20140302266 |
Kind Code |
A9 |
Anker; Martin ; et
al. |
October 9, 2014 |
POLYOLEFIN PIPE WITH IMPROVED MIGRATION BEHAVIOUR
Abstract
The present invention relates to a pipe comprising a polyolefin
composition with low migration of the used additives and its
decomposition products, especially phenolics, out of the
composition, at the same time showing good pressure testing
performance.
Inventors: |
Anker; Martin; (Hisings
Karra, SE) ; Jamtvedt; Svein; (Stathelle,
NO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Anker; Martin
Jamtvedt; Svein |
Hisings Karra
Stathelle |
|
SE
NO |
|
|
Assignee: |
BOREALIS AG
Vienna
AT
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20140037879 A1 |
February 6, 2014 |
|
|
Family ID: |
44584791 |
Appl. No.: |
14/111938 |
Filed: |
January 5, 2012 |
PCT Filed: |
January 5, 2012 |
PCT NO: |
PCT/EP2012/000041 PCKC 00 |
371 Date: |
October 25, 2013 |
Current U.S.
Class: |
428/36.9 |
Current CPC
Class: |
F16L 9/133 20130101;
C08K 5/33 20130101; C08K 5/3462 20130101; C08K 5/3462 20130101;
Y10T 428/139 20150115; C08K 5/3435 20130101; Y10T 428/1393
20150115; F16L 9/12 20130101; F16L 9/127 20130101; C08L 23/02
20130101; C08L 23/02 20130101; C08K 5/3435 20130101; C08K 5/32
20130101; C08L 23/02 20130101; C08K 5/32 20130101 |
Class at
Publication: |
428/36.9 |
International
Class: |
C08K 5/3462 20060101
C08K005/3462; C08K 5/32 20060101 C08K005/32; C08K 5/3435 20060101
C08K005/3435; C08K 5/33 20060101 C08K005/33 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 15, 2011 |
EP |
11003199.4 |
Claims
1-14. (canceled)
15. A pipe comprising a polyolefin composition comprising a) a
polyolefin base resin (A), b) a stabilizer (B) according to formula
(I) ##STR00005## or formula (II) ##STR00006## wherein R.sup.1,
R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are independently from each
other non-substituted or substituted aliphatic or aromatic
hydrocarbyl radicals with not more than 50 carbon atoms each, which
may comprise heteroatoms; c) a stabilizer (C) according to formula
(III) ##STR00007## or formula (IV) ##STR00008## wherein R.sup.6 is
hydrogen or a non-substituted or substituted aliphatic or aromatic
hydrocarbyl radical, which may comprise heteroatoms, R.sup.7,
R.sup.8, R.sup.9 and R.sup.10 are independently from each other
non-substituted or substituted aliphatic or aromatic hydrocarbyl
radicals, which may comprise heteroatoms, R.sup.11 and R.sup.12 are
independently from each other hydrogen or non-substituted or
substituted aliphatic or aromatic hydrocarbyl radicals, which may
comprise heteroatoms, or are together a substituent .dbd.O, and
R.sup.13 and/or R.sup.14 are independently from each other hydrogen
or non-substituted or substituted aliphatic or aromatic hydrocarbyl
radicals, which may comprise heteroatoms.
16. The pipe according to claim 15, wherein the base resin (A)
comprises an ethylene homo- or copolymer.
17. The pipe according to claim 15, wherein stabilizer (B) is
according to formula (I) and stabilizer (C) is according to formula
(III).
18. The pipe according to claim 15, wherein R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 are non-substituted or substituted aliphatic or
aromatic hydrocarbyl radicals, which do not comprise heteroatoms
and comprise between twelve and 25 carbon atoms each.
19. The pipe according to claim 18, wherein R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 are alkyl chains.
20. The pipe according to claim 15, wherein R.sup.5 is an aliphatic
hydrocarbyl radical not comprising heteroatoms and comprises not
more than five carbon atoms.
21. The pipe according to claim 20, wherein R.sup.5 is an alkyl
chain.
22. The pipe according to claim 15, wherein R.sup.6 is a hydrogen
atom or comprises an alkyl chain with 1 to 5 carbon atoms and does
not comprise heteroatoms.
23. The pipe according to claim 15, wherein R.sup.7, R.sup.8,
R.sup.9 and R.sup.10 are alkyl chains comprising 1 to 10 carbon
atoms and do not comprise any heteroatom.
24. The pipe according to claim 15, wherein both R.sup.11 and
R.sup.12 are hydrogen atoms.
25. The pipe according to claim 15, wherein R.sup.13 comprises a
backbone of a polymeric structure, wherein the atom of the
polymeric structure which is directly attached to the carbon atom
of formula (III) or (IV) is a nitrogen atom.
26. The pipe according to claim 15, wherein R.sup.14 is a hydrogen
atom.
27. The pipe according to claim 15, wherein from the polyolefin
composition an amount of at most 5 microgram of phenolic
decomposition and/or by-products per liter of water (microg/liter)
migrates into water, measured according to the migration-into-water
analysis method.
Description
[0001] The present invention relates to a pipe made of a polyolefin
composition providing acceptable process-stability and long-term
stability and at the same time showing low migration of the used
additives and its decomposition products, especially phenolics. The
present invention is also directed to the use of a polyolefin
composition for the production of a pipe which has the advantageous
properties mentioned above. The present invention further relates
to the use of a combination of particular types of stabilizers in a
polyolefin composition for providing acceptable process-stability
and long-term stability to a pipe made of said polyolefin
composition and at the same time maintaining low migration of the
used additives and its decomposition products, especially
phenolics, out of said polyolefin composition or pipe,
respectively.
[0002] Recent progress in the manufacturing and processing of
polymers has led to the application of plastics in virtually every
aspect of modern day life. However, polymeric compounds are prone
to aging under the effects of oxidants, light and heat. This
results in a loss of lifetime such as loss of strength, stiffness
and flexibility, discoloration and scratching as well as loss of
gloss.
[0003] It is well-known in the art that antioxidants and light
stabilizers can prevent or at least reduce these effects. Several
types of additives are added to polymers to protect them during
processing and to achieve the desired end-use properties. Additives
are generally divided in stabilizers and modifiers. Stabilizers,
like antioxidants, traditionally and currently used comprise
sterically hindered phenolics, aromatic amines, hindered amine
stabilizers, organo-phosphites/phosphonites and thioethers.
However, appropriate combinations of stabilizers have to be
carefully selected, depending on the desired final properties, the
polymeric article should have and depending on the field of
application.
[0004] Besides many other applications, polyolefins are used for
the preparation of pipes for drinking water distribution systems.
Due to the permanent contact to the inner pipe surface, compounds
can migrate from the pipe material into the water. The admissible
amounts of compounds within the drinking water are fixed by legal
requirements and even stricter requirements are to be expected in
the future.
[0005] Migration behavior of stabilizers and modifiers added to
polyolefin-based materials is dependent from a number of different
properties such as diffusion rate of the molecules within the
polymer matrix, chemical stability of the additives, etc. Similar
considerations apply for decomposition products of said stabilizers
and modifiers. Furthermore, it has to be taken into account that an
improvement in migration behavior must not be obtained on the
expense of stabilization of the polymer matrix. Thus, providing an
additive composition of low migration tendency is not
straight-forward but rather needs a careful selection of
appropriate compounds.
[0006] GB 2 305 180 discloses polyolefin compositions which are in
permanent contact with extracting media, e.g. water, these
compositions further comprising organic phosphites/phosphonites and
phenolic compounds or sterically hindered amines as stabilizing
components.
[0007] EP 1 911 798 discloses low migration polyolefin compositions
for water pipes comprising a sterically hindered phenolic compound
and an organo-phosphite/phosphonite compound.
[0008] EP 2 014 704 discloses low migration polyolefin compositions
for water pipes comprising a sterically hindered phenolic compound
and a vitamin E-type compound. Particularly the migration of
phenolic decomposition and/or by-products is reduced.
[0009] Generally speaking, phenolic antioxidants play an important
role for such pipe applications. They mainly confer long-term
stability and also process-stability. They are usually added in
combination with phosphite stabilizers which mainly confer
process-stability. Most of them also comprise phenolic residues,
e.g. the 2,4-di-tert. butyl group. Upon hydrolysis phenolic spezies
may be created which can migrate into the drinking water.
[0010] However, considering stricter legal requirements to be
expected in the near future, it is highly appreciated to provide
pipes of high thermal and chemical stability which release only a
very much smaller amount of additives and/or decomposition products
into the water. Particularly, migration of phenolic compounds, e.g.
compounds comprising at least one phenyl residue, into drinking
water is a problem.
[0011] Thus, it is an object of the present invention to provide a
polyolefin composition for pipes showing low migration of the used
additives and its decomposition products, especially phenolic
decomposition and/or by-products, out of the composition, without
losing the stabilisation effect of the stabilisers, in particular
as regards stabilisation during processing and for obtaining the
desired long-term properties.
[0012] The present invention is based on the finding that the
object of the invention can be achieved, if the polyolefin
composition comprises a specific combination of two types of
stabilizers.
[0013] Therefore, the present invention relates to a pipe
comprising a polyolefin composition comprising [0014] a) a
polyolefin base resin (A), [0015] b) a stabilizer (B) according to
formula (I)
[0015] ##STR00001## [0016] or formula (II)
[0016] ##STR00002## [0017] wherein R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 are independently from each other
non-substituted or substituted aliphatic or aromatic hydrocarbyl
radicals with not more than 50 carbon atoms each, which may
comprise heteroatoms; [0018] c) a stabilizer (C) according to
formula (III)
[0018] ##STR00003## [0019] or formula (IV)
[0019] ##STR00004## [0020] wherein [0021] R.sup.6 is hydrogen or a
non-substituted or substituted aliphatic or aromatic hydrocarbyl
radical, which may comprise heteroatoms, [0022] R.sup.7, R.sup.8,
R.sup.9 and R.sup.10 are independently from each other
non-substituted or substituted aliphatic or aromatic hydrocarbyl
radicals, which may comprise heteroatoms, [0023] R.sup.11 and
R.sup.12 are independently from each other hydrogen or
non-substituted or substituted aliphatic or aromatic hydrocarbyl
radicals, which may comprise heteroatoms, or are together a
substituent .dbd.O, and [0024] R.sup.13 and/or R.sup.14 are
independently from each other hydrogen or non-substituted or
substituted aliphatic or aromatic hydrocarbyl radicals, which may
comprise heteroatoms.
[0025] Preferably, the pipe according to the invention consists of
said polyolefin composition, more preferably is made from said
polyolefin composition e.g. by extrusion.
[0026] It has been found that pipes according to the invention both
show process-stability and high long-term stability as measured by
pressure testing also without addition of usual amounts of phenolic
antioxidants or phosphites. This helps to provide low migration of
the used additives and its decomposition products, especially
phenolic decomposition and/or by-products, out of the
composition.
[0027] R.sup.1, R.sup.2, R.sup.3 and R.sup.4 preferably comprise at
least six carbon atoms each. More preferably, R.sup.1 and R.sup.2
comprise at least ten carbon atoms each, even more preferably at
least twelve carbon atoms each.
[0028] R.sup.1, R.sup.2, R.sup.3 and R.sup.4 preferably comprise
not more than 40 carbon atoms each, more preferably not more than
35 carbon atoms each, still more preferably not more than 30 carbon
atoms each and most preferably not more than 25 carbon atoms
each.
[0029] The heteroatoms which may be present in the non-substituted
or substituted aliphatic or aromatic hydrocarbyl radicals R.sup.1,
R.sup.2, R.sup.3, R.sup.4 and/or R.sup.5 of stabilizer (B)
according to formula (I) or (II) may be oxygen, sulphur, nitrogen
and/or phosphorus. It is, however, preferred that R.sup.1, R.sup.2,
R.sup.3, R.sup.4 or R.sup.5, more preferred R.sup.1, R.sup.2,
R.sup.3, R.sup.4 and R.sup.5, do not comprise heteroatoms, i.e. are
non-substituted or substituted aliphatic or aromatic hydrocarbyl
radicals.
[0030] Preferably R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5
comprise non-substituted aliphatic hydrocarbyl radicals, more
preferably alkyl chains.
[0031] R.sup.1 and R.sup.2 is preferably the same organic
residue.
[0032] R.sup.3 and R.sup.4 preferably comprise non-substituted
aliphatic hydrocarbyl radicals, more preferably alkyl chains, with
12 to 25 carbon atoms.
[0033] R.sup.3 and R.sup.4 is preferably the same organic
residue.
[0034] R.sup.5 preferably comprises not more than five carbon
atoms, more preferably not more than three carbon atoms. It is
particularly preferred that R.sup.5 is a methyl group.
[0035] Suitable compounds for formula (I) are e.g.
N,N-dibenzylhydroxylamine (CAS-no. 143925-92-2, Irgastab FS 042
available from Ciba Specialty Chemicals) and
N,N-bis(octadecyl)hydroxylamine (CAS-no. 621-07-8, BNX-2000
available from Mayzo).
[0036] A suitable class of compounds for formula (II) is e.g. a di
(rape-oil) alkyl N-methyl amine oxide (CAS-no. 204933-93-7, Genox
EP available from Chemtura).
[0037] R.sup.6 preferably comprises an aliphatic hydrocarbyl
radical, more preferably an alkyl chain, comprising heteroatoms,
more preferably the amount of carbon atoms is between 1 and 10,
even more preferably between 1 and 5. It is also preferred that
there is an oxygen atom which is directly attached to the nitrogen
atom.
[0038] In a particular preferred embodiment R.sup.6 comprises an
aliphatic hydrocarbyl radical, more preferably an alkyl chain, with
1 to 5 carbon atoms, without any heteroatom, more preferably
R.sup.6 is a methyl group.
[0039] In an alternative particular preferred embodiment R.sup.6 is
hydrogen. R.sup.7, R.sup.8, R.sup.9 and R.sup.10 are independently
from each other preferably non-substituted or substituted aliphatic
hydrocarbyl radicals, which may comprise heteroatoms, more
preferably do not comprise any heteroatom.
[0040] It is further preferred that R.sup.7, R.sup.8, R.sup.9 and
R.sup.10 are independently from each other non-substituted
aliphatic hydrocarbyl radicals, more preferably alkyl chains, which
do not comprise any heteroatom, more preferably comprise 1 to 10
carbon atoms, still more preferably comprise 1 to 5 carbon atoms,
and most preferred are a methyl group.
[0041] In a preferred embodiment the preferred requirements for
R.sup.7, R.sup.8, R.sup.9 and R.sup.10 mentioned above are
fulfilled for all of R.sup.7, R.sup.8, R.sup.9 and R.sup.10 at the
same time, more preferably R.sup.7, R.sup.8, R.sup.9 and R.sup.10
are the same.
[0042] In a particular preferred embodiment R.sup.7, R.sup.8,
R.sup.9 and R.sup.10 are a methyl group.
[0043] R.sup.11 and R.sup.12 are independently from each other
preferably non-substituted or substituted aliphatic hydrocarbyl
radicals, which may comprise heteroatoms, more preferably do not
comprise any heteroatom.
[0044] It is further preferred that R.sup.11 and R.sup.12 are
independently from each other non-substituted aliphatic hydrocarbyl
radicals, more preferably alkyl chains, which do not comprise any
heteroatom, more preferably comprise 1 to 10 carbon atoms, still
more preferably comprise 1 to 5 carbon atoms.
[0045] In a preferred embodiment R.sup.11 and R.sup.12 are
independently from each other non-substituted aliphatic hydrocarbyl
radicals, more preferably alkyl chains, which do not comprise any
heteroatom with 1 to 5 carbon atoms, or hydrogen.
[0046] It is particularly preferred that R.sup.11 and R.sup.12 are
independently selected from hydrogen and a methyl group, more
preferably both R.sup.11 and R.sup.12 are a hydrogen atom.
[0047] In case of a stabilizer (C) according to formula (IV) it is
particularly preferred that R.sup.11 and R.sup.12 are together a
substituent .dbd.O.
[0048] R.sup.13 preferably comprises a backbone of a polymeric
structure, wherein the atom of the polymeric structure which is
directly attached to the carbon atom of formula (III) or (IV) is a
nitrogen atom.
[0049] More preferably, stabilizer (C) according to formula (III)
or (IV) comprises a polymeric backbone with attached groups of
either of formula (III) or (IV), wherein the attachment is via a
nitrogen atom of the backbone to the carbon atom bonded to
R.sup.13. More preferably, the stabilizer (C) comprises only
attached groups according to formula (III). Still more preferably,
two attached groups according to formula (III) are grouped together
insofar that the backbone between the two nitrogen atoms used for
attachment comprises --(CH.sub.2).sub.6--, thereby defining a
backbone unit b1. Even more preferably, two of said backbone units
b1 are connected to each other by a backbone unit b2 which
comprises a 1,3,5-triazine group and b2 is attached to said
nitrogen atom of b1 by carbon atoms 2 and 6 of the 1,3,5-triazine
group. More preferably, the 1,3,5-triazine group comprises
substituents at carbon atom 4, which may comprise heteroatoms. More
preferably, the substituent at carbon atom 4 of said 1,3,5-triazine
group is attached to carbon atom 4 of said 1,3,5-triazine group by
a nitrogen atom.
[0050] Still more preferably said nitrogen atom comprises two
further attached groups selected from hydrogen, C1-C10, preferably
C1-C5 alkyl, and a 4-piperidinyl group, or said nitrogen atom is
part of a 6-morpholino group.
[0051] It is particularly preferred that R.sup.6 is a hydrogen atom
or a methyl group.
[0052] It is particularly preferred that all of R.sup.7, R.sup.8,
R.sup.9 and R.sup.10 are methyl groups.
[0053] It is particularly preferred that R.sup.11 and R.sup.12 are
hydrogen atoms.
[0054] In case of a stabilizer (C) according to formula (III) it is
preferred that R.sup.14 is hydrogen.
[0055] Suitable compounds for formula (III) are e.g. Chimassorb
2020 (CAS-no. 192268-64-7 available from Ciba Specialty Chemicals),
Chimassorb 944 (CAS-no. 71878-19-8 available from Ciba Specialty
Chemicals), Tinuvin NOR 371 (available from Ciba Specialty
Chemicals), Cyasorb UV-3346 (CAS-no. 82451-48-7 available from
Cytec) and Cyasorb UV-3529 (CAS-no. 193098-40-7 available from
Cytec).
[0056] The concentration of stabilizer (B) in the polyolefin
composition is preferably at least 50 ppm, more preferably at least
100 ppm, still more preferably at least 500 ppm based on the total
composition.
[0057] The concentration of stabilizer (B) in the polyolefin
composition is preferably 5000 ppm or less, more preferably 3000
ppm or less, still more preferably 2000 ppm or less, based on the
total composition.
[0058] The concentration of stabilizer (C) in the polyolefin
composition is preferably at least 50 ppm, more preferably at least
100 ppm, still more preferably at least 500 ppm, based on the total
composition.
[0059] The concentration of stabilizer (C) in the polyolefin
composition is preferably 5000 ppm or less, more preferably 3000
ppm or less, based on the total composition.
[0060] The term "base resin" denotes the entirety of polymeric
components in the polyolefin composition according to the
invention, usually making up at least 90 wt % of the total
composition.
[0061] The favourable effect of the stabilizers according to the
present invention is not dependent on the type of polyolefin base
resin used. The base resin may therefore be any polyolefin or
polyolefin composition.
[0062] However, it is preferred that the base resin (A) comprises
an ethylene homo- or copolymer or a propylene homo- or copolymer.
Preferably, the comonomer is selected from ethylene and
alpha-olefins with 4 to 8 carbon atoms. Still more preferably
ethylene or an alpha-olefin selected from 1-butene, 1-hexene,
4-methyl-1-pentene and 1-octene is used.
[0063] The amount of comonomer in the base resin (A) is preferably
between 0.1 mol % and 7.0 mol %.
[0064] It is particularly preferred that the base resin (A)
comprises an ethylene homo- or copolymer, more preferably that the
base resin (A) consists of an ethylene homo- or copolymer.
[0065] In one embodiment of the invention the base resin comprises
two or more polyolefin, more preferably polyethylene, fractions
with different weight average molecular weight. Such resins usually
are denoted as multimodal resins.
[0066] Polyolefin, in particular polyethylene, compositions
comprising multimodal resins are frequently used e.g. for the
production of pipes due to their favourable physical and chemical
properties as e.g. mechanical strength, corrosion resistance and
long-term stability. Such compositions are described e.g. in EP 0
739 937 and WO 02/102891. The term molecular weight used herein
generally denotes the weight average molecular weight M.sub.w.
[0067] As mentioned, usually a polyolefin composition comprising at
least two polyolefin fractions, which have been produced under
different polymerisation conditions resulting in different weight
average molecular weights for the fractions, is referred to as
"multimodal". The prefix "multi" relates to the number of different
polymer fractions the composition is consisting of: Thus, for
example, a composition consisting of two fractions only is called
"bimodal".
[0068] The form of the molecular weight distribution curve, i.e.
the appearance of the graph of the polymer weight fraction as
function of its molecular weight, of such a multimodal polyolefin
will show two or more maxima or at least be distinctly broadened in
comparison with the curves for the individual fractions.
[0069] For example, if a polymer is produced in a sequential
multistage process, utilising reactors coupled in series and using
different conditions in each reactor, the polymer fractions
produced in the different reactors will each have their own
molecular weight distribution and weight average molecular weight.
When the molecular weight distribution curve of such a polymer is
recorded, the individual curves from these fractions are
superimposed into the molecular weight distribution curve for the
total resulting polymer product, usually yielding a curve with two
or more distinct maxima.
[0070] In a preferred embodiment wherein the base resin consists of
two polyethylene fractions, the fraction having a lower weight
average molecular weight is denoted fraction (A), the other is
denoted fraction (B).
[0071] Fraction (A) preferably is an ethylene homopolymer.
[0072] Fraction (B) preferably is an ethylene copolymer, and
preferably comprises at least 0.1 mol % of at least one
alpha-olefin comonomer. The amount of comonomer is preferably at
most 14 mol %.
[0073] In the preferred embodiment wherein the polyolefin
composition is a polyethylene composition, the base resin of the
polyethylene composition preferably comprises at least 0.1 mol %,
more preferably at least 0.3 mol %, and still more preferably at
least 0.7 mol % of at least one alpha-olefin comonomer. The amount
of comonomer is preferably at most 7.0 mol %, more preferably at
most 6.0 mol %, and still more preferably at most 5.0 mol %.
[0074] As an alpha-olefin comonomer, preferably an alpha-olefin
having from 4 to 8 carbon atoms is used. Still more preferably an
alpha-olefin selected from 1-butene, 1-hexene, 4-methyl-1-pentene
and 1-octene is used.
[0075] The polyolefin base resin preferably has an MFR.sub.5
(190.degree. C., 5 kg) of from 0.01 to 5.0 g/10 min, more
preferably from 0.1 to 2.0 g/10 min, and most preferably from 0.2
to 0.5 g/10 min.
[0076] The density of the base resin preferably is from 930 to 960
kg/m.sup.3, more preferably is from 935 to 958 kg/m.sup.3, and most
preferably is from 938 to 952 kg/m.sup.3.
[0077] In addition to the base resin and the stabilizers, usual
additives for utilization with polyolefins, such as pigments (for
example carbon black), further stabilizers, antiacids and/or
anti-UVs, antistatic agents and utilization agents (such as
processing aid agents) may be present in the polyolefin
composition.
[0078] The amount of such additives usually is 10 wt % or
below.
[0079] The polymerisation catalysts for the production of the base
resin include coordination catalysts of a transition metal, such as
Ziegler-Natta (ZN), metallocenes, non-metallocenes, Cr-catalysts
etc. The catalyst may be supported, e.g. with conventional supports
including silica, Al-containing supports and magnesium dichloride
based supports. Preferably the catalyst is a ZN catalyst, more
preferably the catalyst is a non-silica supported ZN catalyst, and
most preferably a MgCl.sub.2-based ZN catalyst.
[0080] The Ziegler-Natta catalyst further preferably comprises a
group 4 (group numbering according to new IUPAC system) metal
compound, preferably titanium, magnesium dichloride and
aluminium.
[0081] The catalyst may be commercially available or be produced in
accordance or analogously to the literature. For the preparation of
the preferable catalyst usable in the invention, reference is made
to WO 2004/055068 and WO 2004/055069 of Borealis and EP 0 810 235.
The content of these documents in its entirety is incorporated
herein by reference, in particular concerning the general and all
preferred embodiments of the catalysts described therein as well as
the methods for the production of the catalysts. Particularly
preferred Ziegler-Natta catalysts are described in EP 0 810
235.
[0082] The composition preferably is produced in a process
comprising a compounding step, wherein the base resin--which is
typically obtained as a base resin powder from the
reactor--together with the stabilizers and optionally other
additives is extruded in an extruder to yield the polyolefin
composition used in the present invention.
[0083] Of course, when using the polyolefin composition, further
compounds selected from conventional additives, fillers, minerals
and lubricants may be added for improving processability and
surface characteristics thereof.
[0084] A pipe according to the present invention--black as well as
natural (i.e. non-colored) or colored pipe is made of the
polyolefin composition, preferably by extrusion. Preferably, the
pipe is used in a drinking water supply system. It is furthermore
preferred that the pipe is a cold water pipe, i.e. that it is
designed for the transport of cold water.
[0085] The present invention is also directed to the use of a
polyolefin composition as defined above, including all of the
preferred embodiments, for the production of a pipe, preferably by
extrusion.
EXAMPLES
1. Definitions and Measurement Methods
a) Density
[0086] Density is measured according to ISO 1183. Sample
preparation is done in accordance with ISO 1872/2B.
b) Melt Flow Rate/Flow Rate Ratio
[0087] The melt flow rate (MFR) is determined according to ISO 1133
and is indicated in g/10 min. The MFR is an indication of the
flowability, and hence the processability, of the polymer. The
higher the melt flow rate, the lower the viscosity of the polymer.
The MFR is determined at 190.degree. C. for polyethylene and may be
determined at different loadings such as 2.16 kg (MFR.sub.2), 5.00
kg (MFR.sub.5) or 21.6 kg (MFR.sub.21).
[0088] The quantity FRR (flow rate ratio) is an indication of
molecular weight distribution and denotes the ratio of flow rates
at different loadings. Thus, FRR.sub.21/5 denotes the value of
MFR.sub.21/MFR.sub.5.
c) Pressure Testing
[0089] The pressure resistance (in hours) of the pipe was
determined according to ISO 1167. The pipes (32 mm outer diameter,
3 mm wall thickness) were tested at different temperature and
pressure as indicated in the individual example (table 1).
d) Measurement of Phenolic Decomposition and/or By-Products
Migration-into-Water
[0090] Pipe samples (32.times.3 mm) were leached with unchlorinated
water according to EN-12873-1 at room temperature (23.+-.2.degree.
C.). Water from the third migration period was analyzed for content
of organic compounds. Water samples were extracted with methylene
chloride. Isotopically labelled internal standards were added to
the water before said extraction. After concentration of the
extracts, isotopically labelled injection standard was added, and
the extracts were analyzed by gas chromatography with mass
selective detector according to the draft CEN standard "The GC-MS
identification of water leachable organic substances from materials
in contact with water intended for human consumption". This draft
CEN Standard has been prepared by CEN TC 164 WG3 AHG7 based on the
co-normative research project EVK1-CT 2000-00052 and work funded by
DG Enterprise and Industry (Grant Agreement S12.403892).
[0091] As procedural blank, ultra pure water (Milli-Q) stored in
acid washed glassware under the same time periods as leaching
tests, was extracted with methylene chloride and all standards were
added as described in the test method.
[0092] The ratio of the surface area (S) of the test piece intended
to come into contact with test water to volume (V) of the test
water shall be expressed per decimeter, i.e. dm.sup.-1 (which is
dm.sup.2/dm.sup.3 or dm.sup.2/liter). Surface-to-volume (S/V) ratio
should be in the range of 5 dm.sup.-1 to 40 dm.sup.-1. In the
present invention the ratio S/V was 15.4 dm.sup.-1.
[0093] The concentrations were then calculated according to
[D]=AD/AI.times.[I]
where [D] is the concentration of a compound D (in .mu.g/liter); AD
is the peak area of compound D; AI is the peak area of the internal
standard; [I] is the concentration of the internal standard (in
.mu.g/liter)
[0094] Phenolic compounds were quantified using the same compounds
as calibrant, where possible. Other phenolic compounds found in the
samples were quantified using structurally similar compounds.
2. Samples Prepared and Results Obtained
[0095] The compositions of the examples were compounded/melt
homogenized in a Buss-Co-Kneader 100 MDK/E-11 L/D. Polymer and
additives were fed into the first mixer inlet of the Buss
Co-Kneader which is a single screw extruder with a downstream
discharge single extruder with pelletizing unit cutting pellets in
molten stage and cooled via water. The mixer temperature profile
was 113/173/199/193/200.degree. C. from first inlet to outlet, and
discharge extruder temperature 166.degree. C. The mixer screw rpm
was 201 rpm and the throughput 200 kg/h. Pipes 32.times.3 mm (outer
diameter.times.wall thickness) were prepared by extrusion in a
Battenfeld 45-25B extruder, which gave an output of 33 kg/h at a
screw speed of 54 rpm. The extruder melt temperature was
215.degree. C. Pipes 12.times.2 mm (outer diameter.times.wall
thickness) were prepared by extrusion in a Battenfeld 45-25B
extruder, which gave an output of 15 kg/h at a screw speed of 20
rpm. The extruder melt temperature was 214.degree. C. 12.times.2 mm
pipes were used in the lifetime tests, 32.times.3 mm pipes in the
migration tests.
[0096] The following compounds were used in the preparation of the
compositions/pipes:
Tris(2,4-di-t-butylphenyl)phosphate (Irgafos 168, CAS-no.
31570-04-4) commercially available from Ciba Speciality Chemicals.
Pentaerythrityl-tetrakis(3-(3',5'-di-tert.
butyl-4-hydroxyphenyl)-propionate (Irganox 1010, CAS-no. 6683-19-8)
commercially available from Ciba Speciality Chemicals. Octadecyl
3-(3',5'-di-tert. butyl-4'-hydroxyphenyl)propionate (Irganox 1076,
CAS-no. 2082-79-3) commercially available from Ciba Speciality
Chemicals. Irgastab FS 042 (CAS-no. 143925-92-2) commercially
available from Ciba Specialty Chemicals). Chimassorb 2020 (CAS-no.
192268-64-7) commercially available from Ciba Speciality
Chemicals.
Carbon Black Masterbatch:
[0097] The carbon black masterbatch (Carbon black MB) contained
60.4 wt % high density polyethylene, 39.5 wt % carbon black and 0.1
wt % Irganox 1010.
Base Resin:
[0098] Polyolefin (A) used as base resin in all samples is an
unstabilised bimodal high density polyethylene with a total
1-butene comonomer content of 1.0 wt % whereby the comonomer is
present exclusively in the high molecular weight part of the
polyethylene, an MFR.sub.5 of 0.25 g/10 min, and a density of 949
kg/m.sup.3.
[0099] Table 1 shows the compositions prepared. If not indicated
otherwise, the values are given in wt %. Still further, in Table 1
the results of the migration testing are also shown, the latter are
given as total amount of phenolic compounds in water. Finally, the
result of pressure testing under different conditions is shown.
TABLE-US-00001 TABLE 1 Comp. Example Example Example 1 1 2 base
resin 93.88 93.89 93.69 Calcium stearate 0.15 0.15 0.15 Carbon
black MB 5.75 5.75 5.75 Irgafos 168/ppm 1100 -- -- Irganox 1076/ppm
1100 -- -- Irgastab FS 042/ppm -- 1100 1100 Chimassorb 2020/ppm --
1000 3000 stabilizers, total/ppm 2200 2100 4100 total amount of
phenolic comp./ppb 0.8 0.0 0.0 time to failure (20.degree. C., 12.4
MPa)/h 571 1191 1382 time to failure (20.degree. C., 12.4 MPa)/h
2618 2132 1538 time to failure (20.degree. C., 12.4 MPa)/h 1395
4088 820 time to failure (20.degree. C., 12.4 MPa)/h .sup.a 1528
2470 1247 time to failure (80.degree. C., 5.0 MPa)/h >15000
>15000 >15000 time to failure (80.degree. C., 5.0 MPa)/h
>15000 14147 >15000 time to failure (80.degree. C., 5.0
MPa)/h >15000 6598 >15000 .sup.a average of three samples
[0100] The requirements of standard EN 12201-2 for PE100 pipes are
fulfilled (20.degree. C., 12.4 MPa: >100 h; 80.degree. C., 5.0
MPa: >1000 h).
* * * * *