MATERIALS FOR PRODUCTION OF CONTAINERS

MATERIAUX POUR LA FABRICATION DE CONTENEURS DE TRANSPORT

English Abstract

The invention relates to the use of polyethylene materials for the production
of solid storage and transportation containers, and also for the production of
lined storage and transportation containers for chemicals, and in particular
for transportation and storage of high-purity, liquid chemicals for the
electronics industry. The invention also relates to the use of said materials
for producing equipment which is required to remove the chemicals from said
containers.

French Abstract

L'invention concerne l'utilisation de matériaux en polyéthylène pour la production de conteneurs pleins de stockage et de transport, et également pour la production de conteneurs de stockage et de transport revêtus destinés à des produits chimiques, et notamment pour le transport et le stockage de produits chimiques de haute pureté destinés à l'industrie électronique. L'invention concerne également l'emploi de ces matériaux pour la production des équipements nécessaires au prélèvement de ces produits chimiques dans lesdits conteneurs.

Claims

CLAIMS
1. Use of HD polyethylene (HD = high density) for the
production of solid storage and transport
containers for high-purity, liquid chemicals for
the electronics industry, characterized in that
the polyethylene has a specific density of 0.940 -
0.970 g/cm3 which, in contact with both high-purity
basic and acidic chemicals, releases ionic
impurities as follows:
Al = 60 ng/g,
Ca = 60 ng/g
Fe = 63 ng/g
Mg = 16 ng/g
Ti = 4.0 ng/g
Zn = 6 ng/g
Mn = 0.3 ng/g and
Cu = 1.5 ng/g.
2. Use according to Claim 1, characterized in that
the HD polyethylene contains no polymerization
catalyst.
3. Use of HD polyethylene (HD = high density) for the
production of solid storage and transport
containers for high-purity, liquid chemicals for
the electronics industry, characterized in that,
without addition of processing auxilliaries, the
polyethylene has a specific density of 0.940 -
0.970 g/cm3 which, in contact with high-purity,
liquid chemicals, releases particularly small
amounts of particles as impurities.
4. Use according to Claims 1-3, characterized in that
the polyethylene has a specific density of 0.942 -
0.961.
5. Use according to Claims 1-4 of HD polyethylene for
the production of linings for storage and

-2-
transport containers for high-purity, liquid
chemicals for the electronics industry.
6. Use according to Claims 1-4 of HD polyethylene for
the production of equipment, in particular
submerged tubes, and liquid-conveying pumps, for
storage and transport containers for high-purity,
liquid chemicals for the electronics industry.
7. Use according to Claim 5, characterized in that
the lining of the storage and transport container
is a two-shell inner container whose inner shell
is made from an HD polyethylene having a
particularly low content of polymerization
catalyst and a specific density of 0.940 -
0.970 g/cm3, in particular a specific density of
0.942 - 0.961, which, both in contact with
high-purity basic and acidic chemicals, releases
particularly small amounts of ionic impurities and
particularly small amounts of particles, which is
surrounded by a glass-fibre-reinforced outer
shell.
8. Use according to Claims 1-7, characterized in that
the HD polyethylene is from the group consisting
of Lupolen 6021 D, Lupolen 5021 D, Lupolen 4261 A
Q149 and Lupolen 4261 A Q 135.
9. Use according to Claims 1-7, characterized in that
the HD polyethylene is Lupolen 4261 A Q149.
10. Storage and transport containers for high-purity,
liquid chemicals for the electronics industry,
made from HD polyethylene having a specific
density of 0.940 - 0.970 g/cm3, in particular a
specific density of 0.942 - 0.961, which, both in
contact with high-purity basic and acidic
chemicals, releases ionic impurities as follows:
Al 60 ng/g, Ca 60 ng/g, Fe 63 ng/g, Mg

-3-
16 ng/g, Ti = 4.0 ng/g, Zn - 6.0 ng/g, Mn =
0.3 ng/g and Cu = 1.5 ng/g, and simultaneously
releases particularly small amounts of particles.
11. Linings for storage and transport containers for
high-purity, liquid chemicals for the electronics
industry, made from HD polyethylene having a
specific density of 0.940 - 0.970 g/cm3, in
particular a specific density of 0.942 - 0.961,
which, both in contact with high-purity basic and
acidic chemicals, releases ionic impurities as
follows: Al = 60 ng/g, Ca = 60 ng/g, Fe = 63 ng/g,
Mg = 16 ng/g, Ti = 4.0 ng/g, Zn = 6.0 ng/g, Mn =
0.3 ng/g and Cu = 1.5 ng/g, and simultaneously
releases particularly small amounts of particles.
12. Submerged tubes for use in storage and transport
containers for high-purity, liquid chemicals for
the electronics industry, made from HD
polyethylene having a specific density of 0.940 -
0.970 g/cm3, in particular a specific density of
0.942 - 0.961, which, both in contact with
high-purity basic and acidic chemicals, releases ionic
impurities as follows: Al = 60 ng/g, Ca = 60 ng/g,
Fe = 63 ng/g, Mn = 16 ng/g, Ti = 4.0 ng/g, Zn =
6.0 ng/g, Mn = 0.3 ng/g and Cu = 1.5 ng/g, and
simultaneously releases particularly small amounts
of particles.
13. Liquid-conveying pumps for high-purity, liquid
chemicals fox the electronics industry, made from
HD polyethylene having a specific density of 0.940
- 0.970 g/cm3, in particular a specific density of
0.942 - 0.961, which, both in contact with
high-purity basic and acidic chemicals, releases ionic
impurities as follows: Al = 60 ng/g, Ca = 60 ng/g,
Fe = 63 ng/g, Mg = 16 ng/g, Ti = 4.0 ng/g, Zn =
6.0 ng/g, Mn = 0.3 ng/g and Cu = 1.5 ng/g, and

-4-
simultaneously releases particularly small amounts
of particles.

Description

CA 02261114 l999-01-lS
.,~. . .~ , 4~
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Materials for the manufacture of transport containers
The invention relates to the use of polyethylene
materials for the manufacture of massive transport and
storage containers and also for the manufacture of lined
transport and storage containers for chemicals,
especially for the transport and storage of high-purity
liquid chemicals for the electronics industry. The
invention further relates to the use of these materials
for the manufacture of the equipment required to dis-
charge the chemicals from the transport containers and tofill said containers.
In many instances the manufacture of electronic
components requires liquid chemicals which are subject to
the strictest purity standards. This is particularly the
case for the manufacture of large-scale integrated
microchips. On the one hand, the purity of these chemi-
cals is at a level where it is not sufficient just to
manufacture the chemicals to the purity demanded; it is
also necessary to ensure that no further impurities enter
the product during shipping or during storage and handl-
ing. On the other hand, the storage and transport safety
must be guaranteed because the aggressive properties of
some of these chemicals makes them difficult to handle
and store. In many cases they are also toxicologically
harmful or have hazardous chemical properties. An
accidental spillage, e.g. due to damage to the transport
container or leaks, caused by the aggressive properties
of some of these chemicals, must be ruled out with a high
degree of certainty.
Because of the demands on the chemicals to be
shipped, the choice of material for such transport
containers must be governed primarily by the exclusion
of any impurities. This demand is normally satisfied by
containers made of fluorinated or perfluorinated
materials or containers lined with such materials.
According to demands, these transport and storage
containers are manufactured as the pressureless version
or as pressure containers.

CA 02261114 1999-01-1
-- 2
Pressureless containers must not be exposed to
any internal pressure applied from outside.
Similarly, the liquid chemicals must be dis-
charged from such containers without the application of
pressure, i.e. with the aid of pumps. These pumps
necessarily have moving parts, so the possibility of
impurities due to wear occurring in the region of the
pumps cannot be completely ruled out.
However, especially where pressure resistant con-
tainers are used, it is known to discharge chemicals byintroducing pressurized inert gases through dip tubes so
that no pumps are required and no wear can thus occur.
DE 36 36 886 has disclosed a transport container for
high-purity liquid chemicals which has a double-shell
inner container, the innermost lining of which consists
of a fluorinated plastic. The multi-shell design of this
transport container is such that it can be pressurized.
The disadvantages, however, are on the one hand that the
only materials suitable for the manufacture of such inner
linings are special fluorinated plastics which have to be
produced in elaborate and therefore expensive processes,
and on the other hand that the processability of these
plastics is made more difficult by the fact that, because
of the high purity demands on the chemicals to be
shipped, not just any processing aids can be added to the
plastic and contamination by tools and environmental
factors has to be extensively minimized.
As regards the choice of material for the manu-
facture of massive transport containers, the polymer
material must have not only resistance to possible
leaching and embrittlement by chemicals to be shipped,
but also an adequate rigidity as well as a degree of
elasticity, so that containers made of the material are
insensitive and stable to pressure and impact and do not
tend to deform or crack. Furthermore, these material
properties must be durable so that, even during prolonged
storage, both the purity of the chemicals to be shipped
and the properties of the container are preserved.
One object of the invention is therefore to

CA 02261114 1999-01-1~
provide a suitable material for the manufacture of
transport containers for high-purity liquid chemicals,
and the associated e~uipment, which is economic to
produce, is obtained in high purity during synthesis,
contains only a very low concentration of polymerization
catalysts, if any, and can be processed easily, if
possible without the addition of processing aids or with
the addition only of processing aids which do not have a
detrimental effect in use or which are not leached out of
the material by the chemicals to be shipped. Another
object of the invention is to provide a suitable polymer
material from which it is possible to manufacture both
massive storage and transport containers for high-purity
liquid chemicals, and linings for corresponding con-
tainers which can be pressurized.
The object is achieved according to the inventionby the use of HD polyethylene (HD = high density) for the
manufacture of massive storage and transport containers
for high-purity liquid chemicals for the electronics
industry, and the associated equipment, and for the
manufacture of linings for corresponding containers which
can be pressurized, and the associated equipment. The
object is achieved in particular by the use of HD
polyethylene with a specific density of 0.940 - 0.970
25 g/cm3, especially 0.942 - 0.961 g/cm3.
According to current opinion, the only suitable
materials for containers which are to be used for ship-
ping high-purity acids or bases are plastics based on
fluorinated hydrocarbons. Examples of such materials are
polytetrafluoroethylene (PTFE), perfluoroalkoxy polymers
(PFA), polyvinylidene fluorides (PVDF) or
poly(ethylene/chlorotrifluoroethylene) (ECTFE), whichare
described in general usage by the well-known trademark
"Teflon". For those skilled in the art, plastics
described as Teflon are insensitive to the effect of
aggressive chemicals such as particularly strong acids or
bases, and also to the effects of temperature. These
plastics are expensive and therefore uneconomic
materials.
. ~ .

CA 0226lll4 l999-Ol-l~
Experiments have now shown, surprisingly, that
non-fluorinated plastics can also be used for the manu-
facture of high-quality transport containers and the
associated equipment, e.g. dip tubes, pump parts and
5 hoses, for high-purity liquid chemicals for the elec-
tronics industry. Selected HD polyethylenes (high
density polyethylenes), namely polyethylenes with a
specific density in the range 0. 940 - 0.970 g/cm3, espec-
ially 0. 942 - 0.961 g/cm3, have proved to be particularly
suitable materials for the desired use. Furthermore,
these polyethylene grades are distinguished analytically
by a particularly low content of catalyst residues.
Therefore, compared with other materials, these materials
release particularly small amounts of ionic impurities
15 when in contact with both basic and acidic high-purity
chemicals. Also, when in contact with chemicals, com-
paratively few particles are produced due to interactions
between the chemicals and the material. This is particu-
larly important with regard to use of the material in the
20 manufacture of the equipment for filling the containers
and discharging the chemicals. Surprisingly, these
materials are suitable both for the manufacture of dip
tubes and for the manufacture of pumps which are required
for discharging the high-purity chemicals from
25 pressureless transport containers and conveying them to
the processing site.
This was particularly surprising because other
corresponding polyethylene materials which for many years
have been used successfully for the transport of hazard-
30 OUS goods are suitable as unsuitable for the transportand storage of high-purity liquid chemicals. When
tested, these plastics were found to release too many
particles and an unacceptable amount of ionic impurities.
Polyethylene materials marketed by BASF under the
35 trademark Lupolen have proved to be particularly suitable
materials for said purpose. In storage tests, the
material grades commercially available under the names
Lupolen 6021 D, Lupolen 5021 D, Lupolen 4261 A Q 149 and
Lupolen 4261 A Q 135 have proved to be particularly

CA 02261114 1999-01-1~
suitable from this group of polyethylene specifications.
These materials are particularly suitable for the
use according to the invention because they are extrudab-
le but can also be welded without a loss of quality.
This affords the possibility of manufacturing almost any
size of container by welding appropriate slabs of this
material. By means of textile fabric applied to one side
of these slabs and anchored in the material, it is
possible to prefabricate relatively thin-walled inner
containers. By the application of glass fibre-reinforced
polyester resin, it is possible to manufacture containers
which are stable per se and which, when designed appro-
priately, comply with the regulations governing pressure
containers. Structurally these containers consequently
have a double-shell design.- In particular, said struc-
ture comprises shells which are joined together, the
inner shell consisting of the HD polyethylene selected
according to the invention and the outer shell consisting
of a glass fibre-reinforced polyester resin. There is
the further possibility of modifying the surface of the
manufactured containers by methods known to those skilled
in the art, for example by painting, backing or disper-
sion coating with suitable barrier polymers or by
covering with thin metal foil. Barrier polymers suitable
for this purpose are polyamide, polyester, polyvinylidene
difluoride or polymers based on acrylonitrile. The
permeability to gases, vapours and liquids can be reduced
in this way.
The values given in the following Tables will
explain the invention in greater detail but are not
intended to limit the invention to said Lupolen poly-
ethylene materials studied.
.

CA 0226lll4 l999-Ol-l~
Table 1
Release of cationic impurities from polyethylene
materials in the presence of high-purity chemicals
Values Lupolen Lupolen Lupolen LLDPE LLDPE VEPE
found in 5021 D 6031 M 6060 D Neste Neste Scair-
ng/g 1st 1st 1stNCPE NCPE link
pelletelution elution elution a682 8682 8000 G
Time: 7Time: 7 Time: 7 1st 2nd 5
days days days
Chemical: Chemical: Chemical: elution 1st elution
HCl 35% HCl 35%HCl 35% Time: 7 Time: 7 Time: 7
40 ~C40 ~C 40 ~C days days days
Chemical: Chemical: Chemical:
HF 49~~F 49% HF 49%
40 ~C 40 ~C 40 ~C
Aluminimum 16 170 8 218 238 815
Antimony - - - - - -
1 0 Arsenic
aarium - - - 3 - 3
Beryllium
i3ismuth - - - 72 84 18
50ron
Cadmium
Calcium 6.6 60 1797 110 147
Chromium 4 0.3 45
Cobalt
Copper
Gallium
Germanium
Gold
Indium
Iron 18 24 13 52 17 86
Lead - - - - - -
Lithium
Magnesium1.5 39 - 62 38 82
Manganese
Molybdenum
Nickel
Platinum - - - - - -
Potassium 3 - _ 30 45 94
Silicon
Silver
Sodium 20 - 16 110 150 300
Strontium
Thallium
Tin - - - - - 1.5
Titanium - 30 - 86 5 16
Vanadium - - - - - 3
Zinc 0.9 3.6 8 4800 714 72
Zirconium
. .

CA 0226lll4 l999-Ol-l~
Table 2
Release of cationic impurities from other polyethylene
materials in the presence of high-purity chemicals
Values Hostalen Hostalen Lupolen Lupolen Lupolen Lupolen
found in GM6255 GM6255 4261A 5261Z 5261Z 6021 D
ng/g 1st 1st Q135 Q135Q445 1st
pelletelution elution 1st lse 1st elution
Time: 6 Time: 26 elution elution elution Time: 7
days days Time: 7 Time: 7Time: 7 days
Chemical: Chemlcal: daysdays days Chemical:
HF 49% HF 49% Chemical: Chemical: Chemical: HCl 35S
25 ~C 25 ~C HCl 35%HCl 35%HCl 35% 40 ~C
40 ~C 40 ~C 40 ~C
Aluminimum 60 0.5 60 1040 110 17
Antimony - - - - - -
1 0 Arsenic
- Barium 1.5 - - - - -
Beryllium - - - - - --
Bismuth - - - - 84
Boron
15 Cadmium
Calcium 90 0.8 10 33 45 3.6
Chromium 13 1.3 70 110 147 3.6
Cobalt
Copper 4 - 1.5
20 Gallium
Germanium
Gold
Indium
Iron 80 2 63 33 33 6.3
25 Lead 0.5
Lithium
Magnesium 26 - 1.5 3 4.5
Manganese 1.3 - 0.3
Molybdenum
30 Nickel 2 - 1.5
Platinum - - - - - -
Potassium 10 - 30 2 1.5 6.3
Silicon
Silver
35 Sodium 7 - 16 36 24 24
Strontium
Thallium
Tin
Titanium - 5 2.5
40 Vanadium
Zinc29 - 1.5 0.3 2.4
Zirconium