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Patent 2205301 Summary

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(12) Patent: (11) CA 2205301
(54) English Title: PROCESS FOR PREPARING POLYETHER ETHER KETONE MEMBRANE
(54) French Title: PROCEDE DE PREPARATION D'UNE MEMBRANE EN POLYETHER ETHER CETONE
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • B01D 67/00 (2006.01)
  • B01D 71/52 (2006.01)
  • C08J 5/18 (2006.01)
  • C08J 9/28 (2006.01)
(72) Inventors :
  • SHIMODA, TERUYOSHI (Japan)
  • HACHIYA, HIROSHI (Japan)
(73) Owners :
  • ASAHI KASEI KOGYO KABUSHIKI KAISHA (Japan)
(71) Applicants :
  • ASAHI KASEI KOGYO KABUSHIKI KAISHA (Japan)
(74) Agent: GOUDREAU GAGE DUBUC
(74) Associate agent:
(45) Issued: 2000-07-25
(86) PCT Filing Date: 1995-12-05
(87) Open to Public Inspection: 1996-06-13
Examination requested: 1997-05-13
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/JP1995/002483
(87) International Publication Number: WO1996/017676
(85) National Entry: 1997-05-13

(30) Application Priority Data:
Application No. Country/Territory Date
6-300803 Japan 1994-12-05

Abstracts

English Abstract




The present invention is directed to a process for
manufacturing a polyether ether ketone (PEEK) membrane which may
be used for ultrafiltration or microfiltration at high
temperatures.
In this process for manufacturing a non-sulfonated PEEK
membrane which comprises dissolving PEEK in a solvent to obtain
a membrane forming stock solution, forming the stock solution
into a desired shape and bringing the formed stock solution in
contact with a coagulating liquid capable of coagulating PEEK,
the key features involve using concentrated sulfuric acid as the
solvent, dissolving PEEK therein to prepare the stock solution
and keeping the stock solution at 15 degrees C or lower until
initiation of membrane formation.


French Abstract

La présente invention concerne un procédé de préparation d'une membrane en polyéther éther cétone utilisable comme ultrafiltre ou microfiltre à haute température. Ce procédé consiste à dissoudre un polyéther éther cétone dans un solvant, puis on coule la solution stable ainsi obtenue pour que la membrane se constitue avec la forme désirée, et l'on met la matière coulée en contact avec un agent solidifiant pour le polyéther éther cétone afin d'obtenir une membrane faite de cette matière non sulfonée, et ce procédé est caractérisé en ce que le solvant utilisé est de l'acide sulfurique concentré et que la solution stable est maintenue à une température égale ou inférieure à 15 DEG C jusqu'à ce que la membrane commence à se former.

Claims

Note: Claims are shown in the official language in which they were submitted.




What is claimed is:
1. In a process for preparing a non-sulfonated polyether
ether ketone membrane which comprises dissolving polyether ether
ketone in a solvent to obtain a membrane forming stock solution,
forming the solution into a desired shape and bringing the
formed solution in contact with a coagulation liquid capable of
coagulating said ketone, the improvement which comprises
(a) using concentrated sulfuric acid as the solvent and
(b) after dissolving said ketone in the solvent,
maintaining the resulting solution at 15 degrees C or
lower until initiation of membrane formation.
2. The process according to claim 1, wherein the
concentration of concentrated sulfuric acid is 94 percent or
more.
3. The process according to claim 1, wherein the membrane
forming stock solution contains a thickening agent.
4. The process according to claim 3, wherein the
thickening agent is polyvinyl pyrrolidone or polyethylene glycol.
5. The process according to claim 1, wherein said ketone
is dissolved in the solvent at a temperature of 15 degrees C or
lower.
6. The process according to claim 1, wherein the
coagulation liquid is water or sulfuric acid having a
concentration lower than 70 percent.
7. The process according to claim 6, wherein the



-55-


coagulation liquid contains a water-soluble organic solvent.
8. The process according to claim 1, wherein the
coagulation liquid is a water-soluble organic solvent.
9. The process according to claim 1, wherein after
membrane formation the membrane is subjected to heat treatment
by using a heat stabilizing solvent under a wet condition at
temperatures between the glass transition point and the melting
point of said ketone.
10. The process according to claim 9, wherein the
temperature of the heat treatment ranges from 150 to 320 degrees
C.
11. The process according to claim 9, wherein the
solubility parameter of the heat stabilizing solvent ranges from
7 to 17.
12. The non-sulfonated polyether ether ketone membrane
obtained in accordance with claim 1.
13. The non-sulfonated polyether ether ketone membrane
obtained in accordance with claim 10.




- 56 -

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 02205301 1997-OS-13
DESCRIPTION
PROCESS FOR PREPARING A POLYETHER ETHER KETONE MEMBRANE
Technical Field
The present invention relates to a process for preparing a
filtration membrane of polyether ether ketone (hereinafter
referred to as PEEK). More particularly, the present invention
relates to a wet, sulfuric acid process for preparing a non-
sulfonated PEEK filtration membrane which may be used as an
ultrafiltration or microfiltration membrane at high temperatures
because of its excellence in mechanical strength and heat and
chemical resistance, and its low elution characteristics.
Background Art
In recent years polymeric separation membranes have widely
been used for the preparation of ultrapure water for
semiconductors in the electronic industry, the filtration,
purification or removal of microorganisms in the medical,
pharmaceutical or food industries, or the filtration of
industrial waste water, etc., and the current trend is one of
continuing expansion in the range and volume of their
applications and use. For example, a separation membrane whose
ion fractions and organic substances are scarcely eluted and
which is excellent in heat and chemical resistance is in demand
for the preparation of ultrapure water for the production of
semiconductors, while at thermal or nuclear power plants a
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CA 02205301 1997-OS-13
separation membrane excellent in heat resistance is in strong
demand for the stable, longtime filtration of condensed water
having temperatures exceeding 100 degrees C. Thus, from the
viewpoint of membrane performance the demand for increased heat
and chemical resistance is growing.
On the other hand, the materials which have widely been
used heretofore for manufacturing separation membranes for
ultrafiltration or microfiltration include cellulose derivatives
such as cellulose acetate, etc., polyacrylonitrile resins,
polyamide resins, polymethyl methacrylate resins, polysulfone
resins, polyvinylidene fluoride resins, polyolefin resins,
polycarbonate resins and the like. However, because of highly
advanced requirements for separation membranes in recent years
as mentioned above, these materials have been unsatisfactory
with regard to their elution characteristics and the heat
resistance and chemical resistance of the membranes made
therefrom.
Attention is being paid to PEEK because of its excellent
heat resistance, chemical resistance and low elution
characteristics, so that this resin has been tried as a material
for filtration membranes. For example, JP-A-61-115954
(equivalent to European patent 182506) describes a separation
membrane of a sulfonated polyaryl ether ketone and a process for
preparing the same. It is however known that such a membrane
swells in water (Macromolecules, 86p, 18, 1985) and therefore
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CA 02205301 1997-OS-13
degrades remarkably in mechanical strength and separation
performance, for example, in water of 60 degrees C or higher.
Further, non-sulfonated PEEK membranes have been proposed.
For example, JP-A-2-136229 (equivalent to U.S. Patent 4,992,485)
proposes a process for preparing a PEEK filtration membrane by
using the membrane casting solution prepared by dissolving a
specifically structured PEEK in a specific non-sulfonating acid
solvent. However, the non-sulfonating acid solvents employed in
this process are strong organic acids such as methane sulfonic
acid, trichloromethane sulfuric acid, etc., hydrofluoric acid or
mixtures of them and concentrated sulfuric acid. They are not
only strong in toxicity and corrosiveness but also high in price
and therefore are not suited for practical use from a commercial
viewpoint. Further, these acids are disadvantageous for
practical use because much work is required to make them
harmless when they are recovered or disposed of as wastes.
Still further, JP-A-3-56129 (equivalent to European patent
382356) and JP-A-5-192550 (equivalent to EP-A-499381) describe
methods of preparing asymmetric polyetherketone resin membranes,
but these methods use the aforementioned specific strong acids
such as methanesulfonic acid, hydrofluoric acid, etc. as
solvents for PEEK.
The acid that may be easily used industrially to dissolve
PEEK is concentrated sulfuric acid, which however has not been
used in general as a solvent for PEEK because it sulfonates the
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CA 02205301 1997-OS-13
phenylene groups between the ether groups of PEEK.
Summary of the Invention
It is an object of the present invention to provide a
process for preparing a PEEK filtration membrane which is not
only substantially non-sulfonated by using concentrated sulfuric
acid, which is easily procured and is inexpensive in the market
instead of organic acids or hydrofluoric acid, but is also
excellent in mechanical strength and heat and chemical
resistance, and has desirably low elution characteristics. The
PEEK membrane obtained according to the present invention is
useful as an ultrafiltration or microfiltration membrane in
fields wherein heat and chemical resistance are necessary.
Detailed Description of the Invention
The present invention provides
(1) in a process for preparing a non-sulfonated PEEK membrane
which comprises dissolving PEEK in a solvent to obtain a
membrane forming stock solution, forming the solution into a
desired shape and contacting the formed solution with a
coagulation liquid, capable of coagulating PEEK, the improvement
which comprises:
(a) using concentrated sulfuric acid as the solvent, and
(b) after dissolving PEEK in the solvent, maintaining the
resulting solution at 15 degrees C or lower until
initiation of membrane formation.
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CA 02205301 1997-OS-13
(2) the process for preparing a membrane as described in (1),
wherein the concentration of concentrated sulfuric acid is 94
percent or more,
(3) the process as described in (1), wherein the membrane
forming stock solution contains a thickening agent,
(4) the process as described in {3), wherein the thickening
agent is polyvinylpyrrolidone or polyethylene glycol,
(5) the process as described in (1), wherein PEEK is dissolved
in the solvent at a temperature of 15 degrees C or lower,
(&) the process as described in (1), wherein the coagulation
liquid is water or sulfuric acid having a concentration lower
than 70 percent,
{7) the process as described in (1), wherein the coagulation
liquid is a water-soluble organic solvent,
(8) the process as described in (6), wherein the coagulation
liquid contains a water-soluble organic solvent,
(9) the process as described in (1), wherein after membrane
formation the membrane is subjected to heat treatment by using a
heat stabilizing solvent under a wet condition at temperatures
between the glass transition point and the melting point of PEEK,
{10) the process as described in (9), wherein the temperature of
the heat treatment ranges from 150 to 320 degrees C,
(11) the process as described in (9), wherein the solubility
parameter of the heat stabilizing solvent ranges from 7 to 17,
(12) the non-sulfonated PEEK membrane obtained in accordance
- 5 -


CA 02205301 1997-OS-13
with (1), and
(13) the non-sulfonated PEEK membrane obtained in accordance
with (10)
The PEEK membrane obtained according to the process of
the present invention retains the heat and chemical resistance
that PEEK has intrinsically in spite of using concentrated
sulfuric acid which is procurable at low prices and is widely
employed in the manufacturing industries. Further, the heat
treatment for raising the crystallinity of the said membrane by
using a heat stabilizing solvent at a wet condition makes it
possible to obtain a heat resistant membrane durable even in
water of 130 degrees C or higher.
The membrane of the present invention is prepared in
accordance with a wet membrane production process. For example,
in the field of polymers such as cellulose, etc., the process
has been described by Zeob and Sourirajan (see Adv. Chem. Ser.
38, 117, 1963).
The process of the present invention at least comprises
the following steps:
(A) dissolving PEEK in concentrated sulfuric acid to
prepare a membrane forming stock solution,
(B) forming the solution into a desirable shape,
(C) coagulating the formed solution in a coagulation
liquid, and
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CA 02205301 1997-OS-13
(D) washing to remove the concentrated sulfuric acid
remaining in the resulting PEEK membrane.
First, step (A) will be described hereinafter. PEEK used
in accordance with the present invention is composed of the
repeating units represented by formulas of Group 1. It may be
either a homopolymer comprising the repeating units or a
copolymer comprising the repeating units represented by two or
more of these formulas. The phenylene groups of the said
repeating units may contain lower alkyl groups, halogen groups,
nitro groups, nitrile groups, amino groups, phenoxyl groups,
phenyl groups, biphenyl groups and substituents represented by
the formulas of Group 2.
Group
-o~-o-C- co--~o y
-o~o -o~o -co- o~co-0-
-O-~O -O O~ COO -O~O - CO- O~ (3)
-O O O -O~O -CO~ (4)
-o~o -o ~o - co-~o ~ coo -
-O~O - OO~-~O - COO -O-~O -CO-~O (6)
O O
_o-~O -COO _ (~)
_ ~ _


CA 02205301 1997-OS-13
O O -O-~O --CO
~ ~ -O-O~O~O -CO~ (9)
O O
_-O~-CO O O -COO (l0)
Group 2
~- CO
O
~- SOz- OO
-CHr OO
CHa
CHs
The homopolymers or copolymers comprising the repeating
units represented by the formulas of Group 1 may contain as
parts thereof, i.e., as copolymeric components, other repeating
units, for example, those having structures as represented by
the formulas of Group 3, within such quantities as may not
remarkably deteriorate the inherent properties of the said
homopolymers or copolymers.
_ g _


CA 02205301 1997-OS-13
Groin 3
-o- o~-soZ ~o -
-o~o - soz~o O- soZ-~O -
-o~o -s~o -soZ~o
-s~o -o~soz-~-
-o-~O -o- o~ soZ ~o
-o- o 0 o~soZ~o -
-o-Oo -o-~o - o~- so2- o~
CHa
-O- O~- i ~O ~ SOz - O~-
CHs
CHs
-O~O - SOz- O~-O-( ~ SOz ~O -
CHs
_ g _


CA 02205301 1997-OS-13
-O O~ SOz SOz ~-
O~CO-~~-CO- O
~CwO~H~OiC~_O~
CN
i
~O--~ O
U U
CN
v v
-~O- O
PEEK used in the present invention may be produced by
known polymerization methods. As an example thereof, there may
be mentioned a method of condensation polymerizing an aromatic
dihalogen compound and a diphenol in the presence of an alkali
salt. The said polymerization method is described in JP-B-57-
22938, U.S. patents 4,113,699 and 4,320,224 and JP-A-54-90296.
The polymerization degree of PEEK used in the present invention
is not particularly limited. The polymerization degree of PEEK
- 10 -
O


CA 02205301 1997-OS-13
is expressed as reduced viscosity obtained from measurements at
25 degrees C with an Ostwald viscometer of a 0.1 percent PEEK
solution (PEEK weight/concentrated sulfuric acid volume), the
solvent being concentrated sulfuric acid having a density of
1.83g/cm3. The measurement should be performed in the vicinity
of 25 degrees C immediately after PEEK is dissolved in order to
minimize the influence of sulfonation. The viscometer of ca.
two minute solvent efflux time is used in the measurement. The
reduced viscosity of PEEK used in the present invention is
ordinarily in the range of 0.5 to 2.5 d~/g. In order to obtain
high mechanical strength of the resulting membrane, it is
preferred that the reduced viscosity is in the range of 0.8 to
2.5 dQ/g.
Furthermore, the particle size of PEEK used according to
the present invention is not especially restricted, but the
smaller the better to accelerate the dissolving rate thereof
against concentrated sulfuric acid. For example, the particle
size of PEEK is 5 mm or smaller, preferably 1 mm or smaller and
more preferably 0.5 mm or smaller. PEEK may be used in the form
of pulverulent bodies obtained by polymerization or smaller
particles obtained by grinding pellets thereof.
According to the present invention, concentrated sulfuric
acid refers to that having a concentration of at least 85
percent or oleum. When PEEK of especially higher molecular
weight is dissolved or when the PEEK concentration is raised in
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CA 02205301 1997-OS-13
a membrane forming stock solution, it is preferred to raise the
concentration of concentrated sulfuric acid to 90 percent or
more. When the PEEK concentration is further raised in the
membrane forming stock solution or when the membrane forming
stock solution contains an additive, thickening agent or the
like, the concentration of concentrated sulfuric acid is
preferably at least 94 percent, particularly preferably at least
98 percent in order to raise the dissolvability of PEEK, the
additive, thickening agent and the like. According to the
present invention, the concentration of sulfuric acid is
expressed as percent by weight of the concentrated sulfuric acid
content when 100 percent concentrated sulfuric acid is diluted
with water.
According to the present invention, the temperature and
time required to dissolve PEEK in concentrated sulfuric acid are
not especially restricted if the ion exchange capacity of the
resulting PEEK filtration membrane is in the range of 0 to 0.5
meq./g. The temperature depends upon the molecular weight of
PEEK, the PEEK concentration of the membrane forming stock
solution and the concentration of concentrated sulfuric acid,
but should normally be within the range that may keep the
membrane forming stock solution in a liquid state. The time
necessary to completely dissolve PEEK ordinarily ranges from 3
to 100 hours. Especially, the temperature while dissolving PEEK
is preferably 15 degrees C or lower, more preferably 10 degrees
- 12 -


CA 02205301 1997-OS-13
C or lower. Further, in step (A), deaeration may be performed
under vacuum in the course of dissolving PEEK or immediately
after PEEK is dissolved.
According to the present invention, an inorganic compound,
lower molecular weight organic compound or the like may be added
as an additive to the aforesaid membrane making stock solution
to control the pore size of the resulting membrane. As
inorganic compounds, various salts may be used, while as lower
molecular weight organic compounds, compounds having a molecular
weight of 1, 000 or lower may be preferably used. As such lower
molecular weight compounds, listed are diphenylsulfone, 4,4'-
dichlorodiphenylsulfone, 2,4'-dichlorodiphenylsulfone, 4,4'-
difluorodiphenylsulfone, 2,4'-difluorodiphenylsulfone, 2,2'-
difluorodiphenylsulfone, benzophenone, 4,4'-dichlorobenzo-
phenone, 2,4'-dichlorobenzophenone, 4,4'-difluorobenzophenone,
2,4'-difluorobenzophenone, 2,2'-difluorobenzophenone, 4,4'-
difluoroterephthalophenone, 2,4'-difluoroterephthalophenone,
4,4'-dichloroterephthalophenone, 2,4'-dichloroterephthalophenone,
N,N-dimethylformamide, N,N-dimethylacetoamide, dimethyl-
sulfoxide, N-methylpyrrolidone, xanthone, terephthalic acid,
isophthalic acid, salicylic acid, halogenated hydrocarbons, 1,4-
butanediol, 1,3-butanediol, ethyleneglycol, diethyleneglycol,
triethyleneglycol, tetraethyleneglycol, ethyleneglycol mono-
methylether, diethyleneglycol monomethylether, triethyleneglycol
monomethylether, tetra-ethyleneglycol monomethylether, ethylene-
- 13 -

CA 02205301 1997-OS-13
glycol dimethylether, diethyleneglycol dimethylether,
triethyleneglycol dimethylether, tetraethyleneglycol
dimethylether, ethyleneglycol monoethylether, diethyleneglycol
monoethylether, triethyleneglycol monoethylether, tetra-
ethyleneglycol monomethylether, ethyleneglycol diethylether,
diethyleneglycol dimethylether, triethyleneglycol diethylether,
tetraethyleneglycol dimethylether, ethyleneglycol monoiso-
propylether, diethyleneglycol monoisopropylether, triethylene-
glycol monoisopropylether, tetraethyleneglycol monoisopropyl-
ether, propyleneglycol monoisopropylether, ethyleneglycol di-
isopropylether, diethyleneglycol diisopropylether, triethylene-
glycol diisopropylether, tetraethyleneglycol diisopropylether,
ethyleneglycolmonophenylether, diethyleneglycol monophenylether,
triethyleneglycol monophenylether, tetraethyleneglycol mono-
phenylether, ethyleneglycoldiphenylether, diethyleneglycol
diphenylether, triethyleneglycol diphenylether, tetraethylene-
glycol diphenylether, dichloroacetic acid, trichloroacetic acid,
difluoroacetic acid, trifluoroacetic acid, methanesulfonic acid,
chloromethanesulfonic acid, dichloromethanesulfonic acid,
trichloromethanesulfonic acid, f luoromethanesulfonic acid,
difluoromethanesulfonic acid, trifluoromethanesulfonic acid,
glycerol and the like. It is preferred that they are uniformly
dissolved in the membrane forming stock solution. They may be
dispersed in a microfine state or modified to such an extent so
as not to have any bad effect on the performance of the
- 14 -

CA 02205301 1997-OS-13
resulting membrane.
Furthermore, a thickening agent such as a water-soluble or
water-insoluble inorganic compound or high molecular weight
organic compound, oligomer thereof or the like may be added for
the purpose of controlling the viscosity of the above-mentioned
membrane forming stock solution. Examples of the inorganic
compounds include utrafine silica and the like which give a
thixotropic property to the membrane forming stock solution and
examples of the high molecular weight organic compounds include
polyvinylpyrrolidone, polyethyleneglycol, polyethyleneglycol-
monoalkylethers, polyethyleneglycoldialkylethers, sulfonated
polyetherketone, polysiloxane, polyethersulfone, polysulfone,
polyetherimide, etc., mixtures thereof and oligomers thereof.
Among them, polyvinylpyrrolidone or polyethyleneglycol is
preferably used. These thickening agents may be modified in the
membrane forming stock solution to such an extent that they do
not affect the performance of the resulting membrane.
The component ratios of the membrane forming stock
solution used in the instant invention are not especially
limited if respective components are dissolved uniformly therein.
Normally, the membrane forming stock solution of the present
invention comprises 5 - 20 parts by weight of PEEK, 30 - 95
parts by weight of concentrated sulfuric acid, 0 - 20 parts by
weight of an additive and 0 - 60 parts by weight of a thickening
agent per 100 parts by weight of the stock solution. The amount
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CA 02205301 1997-OS-13
of said additive is less than 40 percent by weight based on the
weight of concentrated sulfuric acid used therein. The
viscosity of the stock solution thus prepared according to the
aforesaid component ratios and used in the instant invention
ranges from 50 to 1,000 poise at a temperature of 15 degrees C.
In step (A) of the instant invention, it is preferred that
agitation is carried out in a closed system to prevent the
component ratios from changing because of the hygroscopic
property of concentrated sulfuric acid. In this case, the
membrane forming stock solution is prepared under vacuum or in
the presence of a water vapor-free gas such as dried nitrogen
gas. On the other hand, the hygroscopicity of concentrated
sulfuric acid may be controlled by adjusting the humidity in the
atmosphere of the membrane forming stock solution and as a
result, this makes it possible to adjust the water content of
the stock solution.
It is preferred that the state of the membrane forming
stock solution used in the present invention is one which is in
the neighborhood of microphase separation. If the stock
solution is in such a state, the resulting filtration membrane
tends to increase in water permeability. By the term
"microphase separation" mentioned in the present invention is
meant a suspended state in which a polymer rich phase of the
stock solution has been separated from a polymer poor phase by
the addition of water in extremely small increments to the
- 16 -

CA 02205301 1997-OS-13
prepared stock solution, with one of the phases being dispersed
as microfine particles in the other phase. Particularly, the
neighborhood of the microphase separation refers to the
concentrative composition of the stock solution which may
undergo the said microphase separation when 0.01 - 3 parts by
weight, preferably 0.05 - 2 parts by weight of water, is added
to 100 parts by weight of the stock solution at a membrane
formation temperature. Therefore, for the purpose of making the
stock solution one which is in the neighborhood of the
microphase separation it is important to accurately control the
ratio of each of the components such as the concentrated
sulfuric acid, additive, thickening agent, and the like.
Following step (A), step (B) of forming the membrane
forming stock solution into a desirable shape and step (C) of
coagulating the shaped membrane forming stock solution in a
coagulation liquid proceed in order.
According to the present invention, it is necessary to
cool the membrane forming stock solution immediately after step
(A) and to keep the temperature of the stock solution at 15
degrees C or lower until the beginning of membrane formation.
This temperature also refers to that of the piping and tanks in
which the stock solution is detained or stored in the course of
membrane formation and is preferably 10 degrees C or lower and
more preferably 6 degrees C or lower. The temperature of the
stock solution has a great influence on the sulfonation,
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CA 02205301 1997-OS-13
mechanical strength and chemical resistance of the filtration
membrane obtained according to the present invention.
The membrane forming stock solution may be deaerated
between steps {A) and (B). The method of deaeration is not
especially restricted, but the deaeration is carried out
generally under vacuum or by means of centrifugal separation.
In general, there is the possibility that the resulting
filtration membrane will have pinholes if the deaeration step is
omitted.
According to the present invention, the form of the
membrane obtained in step (B) is that of a flat-sheet, hollow
fiber, tubular and capillary membrane, though the form is not
especially limited. Examples of methods for forming a flat-
sheet membrane include application of the membrane forming stock
solution to a support and the consecutive immersion thereof in a
coagulation liquid, extrusion of the membrane forming stock
solution through a slit die into a coagulation liquid, and the
like. Examples of the supports not attacked immediately by
concentrated sulfuric acid include sheets of stainless steel,
polyethylene, polypropylene, polytetraf luoroethylene, glass and
the like. To obtain tubular, hollow fiber or capillary
membranes, a coaxial double-tube die is used, through an annular
orifice of which a membrane forming stock solution is extruded
and through the bore of which a liquid such as a good solvent or
non-solvent for the PEEK or an inert gas as a bore coagulant is
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CA 02205301 1997-OS-13
passed, and the stock solution thus extruded is immersed in a
coagulation liquid.
The thickness of the PEEK membrane obtained in the instant
invention is not particularly limited but ranges normally from 5
to 10,000 um. Particularly, if the form of the membrane is that
of a hollow fiber membrane, a membrane with a wall thickness
ranging from 5 to 2,000 um and an inside diameter ranging from
to 5,000 um may be produced preferably but the thickness and
inside diameter are not especially limited.
Furthermore, according to the present invention, it is
possible to obtain a composite membrane which may be produced by
flow casting a membrane forming stock solution on a porous
fabric substrate and coagulating it integrally. Examples of
materials for the porous substrates normally include fabrics of
polyethylene, polypropylene, polytetrafluoroethylene, polyester,
PEEK, polyether ketone (PEK), polyphenylenesulfide, carbon fiber
and glass fiber.
In step (B), the temperature of the membrane forming stock
solution is ordinarily 80 degrees C or lower and falls within a
range where the solution is in a liquid state. For example, if
the membrane forming stock solution is formed into a flat-sheet
membrane or hollow fiber membrane by use of a flat slit die or a
coaxial double-tube die, the temperature of the stock solution
may be adjusted by controlling the temperature of the said dies
so that it may be within the above-mentioned temperature range.
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CA 02205301 1997-OS-13
In this case, the temperature of the piping and tanks wherein
the stock solution is detained or stored is, of course, 15
degrees C or lower as mentioned hereinbefore.
The coagulation liquids used in step (C), are sufficient
if they are capable of coagulating PEEK and are mixable with
concentrated sulfuric acid and for example, include water,
dilute sulfuric acid, acetic acid, acetic acid ester, alcohols,
polyhydric alcohols, monoalkylethers of glycols, dialkylethers
of glycols, ketones, polymer-containing solutions, and mixtures
thereof. Further, inorganic salts or bases may be added to the
coagulation liquids. As the inorganic salts, preferably used
are, for example, lithium chloride, sodium chloride, calcium
chloride, magnesium chloride, ammonium chloride, ammonium
nitrate, lithium sulfate, magnesium perchlorate, sodium
perchlorate, sodium hypochlorite, sodium hydroxide, potassium
hydroxide, sodium carbonate, potassium carbonate, potassium
hydrogen carbonate and the like.
Particularly if a coagulation liquid highly capable of
coagulating the membrane forming stock solution is used, a
membrane having high fractionating characteristics tends to be
preferably obtained. Such coagulation liquids are, for example,
water and sulfuric acid having a concentration of less than 70
percent.
If a coagulation liquid low in the capability of
l... ~ ,.,~ i ., .~ ; ., ~. ~..~ _,,.. r _ _ s _ _
v.va.yuia.uimg ~mC Weu~tdme i~iW ing S'COCk SOlutlOn 1S uSeCl, a
- 20 -

CA 02205301 1997-OS-13
highly water-permeable membrane tends to be obtained.
Coagulability may be adjusted by using a water-soluble
organic solvent, a mixture of a water-soluble organic solvent
and water, a mixture of a strong acid and water, a mixture of a
strong acid and a water-soluble organic solvent or the like as a
coagulation liquid.
The surface of the formed stock solution may be contacted
with the vapor of a non-solvent against PEEK immediately before
the said solution is immersed in the coagulation liquid.
Particularly, if the form of the membrane is that of a
tube, hollow fiber or capillary tube, bore coagulants similar to
the aforesaid coagulation liquids may be used and they may be
the same as or different from the coagulation liquids. Various
inert gases may be used as the bore coagulants.
If the temperature of the membrane forming stock solution
is within a range where PEEK may not be substantially sulfonated
during membrane formation, the said temperature is not
especially limited but is normally in the range of the freezing
point of the stock solution to 80 degrees C. If the stock
solution is formed by use of a slit die or coaxial double-tube
die, the temperature of the stock solution during membrane
formation may be controlled by heating the said die. If the
temperature of the solution is, for example, 15 degrees C or
higher, it is preferred to shorten its detention time in the die
to minimize the sulfonation of PEEK.
- 21 -

CA 02205301 1997-OS-13
Further, the range of -10 to 90 degrees C that does not
sulfonate PEEK substantially may be adopted as the temperature
of the coagulation liquids and the bore coagulants used for
forming a hollow fiber membrane.
According to the present invention, the shaped membrane
forming stock solution may be stretched when or after it is
coagulated, if necessary.
Step (C) is followed by Step {D) in which residual
sulfuric acid is washed away from the resulting PEEK filtration
membrane. Further, in step (D), the additive, thickening agent
and coagulation liquid which are used in the membrane forming
stock solution are also removed from the resulting PEEK
filtration membrane in addition to the removal of the residual
sulfuric acid. However, step (D) may be omitted if the residual
sulfuric acid, additive and thickening agent are removed before
step (D) to such an extent that problems do not occur in the
heat treatment discussed hereinafter or in the use of the
resulting filtration membrane.
In step (D), the residual sulfuric acid and other
components are removed, for example, by means of the washing
treatment wherein an aqueous solvent or a solvent mostly
consisting of water is used as a washing solvent at temperatures
within the range between 5 degrees C and the boiling point of
water. Normally, water or an alkaline water is used preferably.
Particularly, if the form of the PEEK ffiltration membrane is
- 22 -

CA 02205301 1997-OS-13
that of a tube, hollow ffiber or capillary tube, it is also
effective to pass the said washing solvent through its bore.
If a small amount of sulfuric acid still remains in the
said membrane after step (D), it may be further rinsed with an
organic solvent. As the organic solvents, normally used are
methanol, ethanol, propanol, acetone, methylethylketone,
ethylene glycol, diethylene glycol, triethylene glycol,
dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone,
etc. For example, the range of -5 to 120 degrees C may be
adopted as the temperatures of the said organic solvents. If
thickening agents or additives insoluble to aqueous solvents are
used in step (A), the above-mentioned organic solvents are
preferable for washing and removing. Further, if polyvinyl
pyrrolidone is used as a thickening agent in step (A), residual
polyvinyl pyrrolidone may be decomposed, removed and rinsed with
an aqueous solution of a hypochlorite such as sodium
hypochlorite or the like, for example, after the above-mentioned
washing is performed. In this case, decomposition, removal and
rinse may be performed normally with an aqueous solution of a
100 - 80,000 ppm hypochlorite at temperatures of 5 - 95 degrees
C for 1 - 500 hours. It is also effective to make the resulting
PEEK filtration membrane sufficiently hydrophilic in advance by
immersing it in an aqueous organic solution such as ethanol or
the like.
After step (D), it is preferred to preserve the PEEK
- 23 -

CA 02205301 1997-OS-13
membrane from being dried, i.e., under the condition of
immersing the membrane in water, an alcohol, an aqueous solution
of an alcohol, formalin or a mixture thereof, or under the
condition of impregnating an aqueous solvent thereof into the
inside and the surface of the membrane. A preferred way of
preservation is to immerse the membrane in formalin or, to
immerse it in or to impregnate it with an alcohol such as
ethylene glycol, diethylene glycol, triethylene glycol,
tetraethylene glycol, propylene glycol, dipropylene glycol,
tripropylene glycol, low molecular weight polyethylene glycol,
glycerol or the like or a mixture thereof. If the PEEK membrane
is dried after step (D), its water permeability tends to be
lowered, which is not preferred.
In accordance with the present invention, it is preferred
to subject the membrane to heat treatment after the above-
mentioned rinse step by using a heat stabilizing solvent under a
wet condition at temperatures between the glass transition and
melting points of PEEK. The temperature of the heat treatment
ranges preferably from the glass transition point plus 20
degrees C to the melting point minus 20 degrees C of PEEK and
more preferably from the glass transition point plus 50 degrees
C to the melting point minus 50 degrees C. For example, if PEEK
is composed of the repeating units represented by formula (1) of
Group 1, the temperature of the heat treatment ranges preferably
from 150 to 320 degrees C and more preferably from 200 to 280
- 24 -

CA 02205301 1997-OS-13
degrees C. The glass transition and melting points of PEEK
mentioned in the present invention mean those obtained by
measuring with a differential thermal analyzer while raising the
temperature at a rate of 10 degrees C/min.
In accordance with the instant invention, the PEEK
membrane is maintained under the wet condition during the heat
treatment by use of a heat stabilizing solvent. The heat
stabilizing solvents mentioned in the present invention mean
those that are used for the heat treatment to increase the
crystallinity of the PEEK membrane and maintain the membrane in
the wet condition during the treatment. Further, the wet
condition mentioned in the present invention refers to the
condition wherein the said membrane is wet with the heat
stabilizing solvent used for the heat treatment. In more detail,
it refers to the condition wherein the membrane is wet from its
surface to the inside with the heat stabilizing solvent or the
like that may bring about the wet condition or the condition
wherein the membrane is wholly immersed in the said solvent.
The condition is attained by applying or atomizing the solvent
to the surface of the PEEK membrane, impregnating the solvent
into the membrane or immersing the membrane in the said solvent.
For example, a desirable wet condition according to the instant
invention is the condition wherein the said solvent is uniformly
applied to or impregnated into the PEEK membrane 0.5 time or
more, preferably 2 times or more, more preferably 10 times or
- 25 -

CA 02205301 1997-OS-13
more based on the weight of the PEEK membrane, although
depending upon the porosity of the PEEK membrane and the
specific gravity of the solvent used for obtaining the wet
condition.
The heat stabilizing solvents used for the heat treatment
of the present invention are not limited to specific ones if
they are solvents that do not dissolve the PEEK membrane and
that are stable during the said treatment. Of them, the
solvents with solubility parameters of 7 to 17 are used
preferably. The solvents having solubility parameters ranging
more preferably from 7 to 15, particularly preferably from 8 to
13 are used. If a heat stabilizing solvent outside the above
ranges is used, the water permeability of the resulting PEEK
membrane is remarkably lowered.
The solubility parameter according to the instant
invention is denoted by the following formula:
solubility parameter = (pEV/V)li2
wherein dE~ is molar evaporation energy, nearly equal to dH - RT
wherein DH is vapor heat, R is the gas constant and T is
absolute temperature, and V is the molar volume of a solvent.
Solubility parameters are described in many scientific
literatures and books. Particularly, "Polymer Data Handbook,
Basic Edition", compiled by The Society of Polymer Science,
- 26 -

CA 02205301 1997-OS-13
Japan and published by Baifukan Co., Ltd. has tables on
solubility parameters by solvent, so that a decision may be made
on the choice of the heat stabilizing solvents suitable for the
instant invention.
Other literatures giving considerations to solubility
parameters inc lude Ind . Chem. Prod . Res . Dev . 8 , Mar . 19 6 9 , p . 2
- 11, Chemical Reviews, 75(1975), p.731 - 753, and Encyclopedia
of Chemical Technology, 2nd Edition, Supplement Volume (1971),
p.889 - 910.
Examples of the heat stabilizing solvents used according
to the present invention include alcohols such as methanol,
ethanol, n-propanol, n-butanol, isobutanol, sec-butyl alcohol,
t-butyl alcohol, n-pentanol, n-hexanol, 2-ethylbutanol, n-
octanol, ethyl hexanol, 1-dodecanol, 3,5,5,-trimethyl hexanol,
cylohexanol, methyl isobutylcarbinol, n-amyl alcohol, allyl
alcohol, lauryl alcohol, benzyl alcohol, furfuryl alcohol, n-
heptanol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol,
ethylene glycol, diethylene glycol, triethylene glycol, tetra-
ethylene glycol, propylene glycol, dipropylene glycol, tri-
propylene glycol, tetraethylene glycol, neophenyl glycol, 1,5-
pentanediol, 2,4-pentanediol, 2,5-pentanediol, glycerol,
polyethylene glycol, polypropylene glycol and the like, ethers
such as dimethyl ether, diethyl ether, ethyl methyl ether,
isopropyl ether, dipropyl ether, diisopropyl ether, butyl ether,
dibenzyl ether, dihexyl ether, diamyl ether, ethyl isobutyl
- 27 -

CA 02205301 1997-OS-13
ether, methylisobutyl ether, diacetone alcohol methyl ether,
dichloroethyl ether, diphenyl ether, ethyleneglycol monomethyl
ether, diethyleneglycol monomethyl ether, triethyleneglycol
monomethyl ether, tetraethyleneglycol monomethyl ether,
propyleneglycol monomethyl ether, ethyleneglycol dimethyl ether,
diethyleneglycol dimethyl ether, triethyleneglycol dimethyl
ether, tetraethyleneglycol dimethyl ether, propyleneglycol
dimethyl ether, ethyleneglycol monoethyl ether, diethyleneglycol
monoethyl ether, triethyleneglycol monoethyl ether,
tetraethylene glycol monomethyl ether, propyleneglycol monoethyl
ether, ethyleneglycol diethyl ether, diethyleneglycol dimethyl
ether, triethyleneglycol diethyl ether, tetraethyleneglycol
dimethyl ether, propyleneglycol diethyl ether, ethyleneglycol
monoisopropyl ether, diethyleneglycol monoisopropyl ether,
triethyleneglycol monoisopropyl ether; tetraethyleneglycol mono-
isopropyl ether, propyleneglycol monoisopropyl ether,
ethyleneglycol diisopropyl ether, diethyleneglycol diisopropyl
ether, triethyleneglycol diisopropyl ether, tetraethyleneglycol
diisopropyl ether, propyleneglycol diisopropyl ether,
ethyleneglycol monophenyl ether, diethyleneglycol monophenyl
ether, triethyleneglycol monophenyl ether, tetraethyleneglycol
monophenyl ether, propyleneglycol monophenyl ether, ethylene-
glycol diphenyl ether, diethyleneglycol diphenyl ether,
triethyleneglycol diphenyl ether, tetraethyleneglycol diphenyl
ether, propyleneglycol diphenyl ether, methyl-2-pentanediol-1,3-
- 28 -

CA 02205301 1997-OS-13
methyl-2-pentanediol-2,4, ethylhexanediol-1,3 and the like,
acetals such as 1,4-dioxane, furan, furfural, tetrahydrofuran
and the like, esters such as methyl acetate, ethyl acetate, n-
propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl
acetate, sec-butyl acetate, n-amyl acetate, isoamyl acetate,
sec-amyl acetate, vinyl acetate, allyl acetate, methylamyl
acetate, butyl stearate, methyl formate, ethyl formate, propyl
formate, n-butyl formate, isobutyl formate, n-amyl formate,
isoamyl formate, methyl butyrate, ethyl butyrate, isobutyl
butyrate, n-butyl butyrate, propyl butyrate, isopropyl
isobutyrate, methyl propionate, ethyl propionate, butyl
propionate, propyl propionate, ethyl lactate, methyl lactate, n-
butyl lactate, methyl benzoate, ethyl benzoate, ethyl acrylate,
methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl
methacrylate, methyl isobutyrate, ethyl isobutyrate, dimethyl
phthalate, diethyl phthalate, dipropyl phthalate, dibutyl
phthalate, dimethyl oxalate, diethyl oxalate, dimethyl sebacate,
diethyl sebacate, dibutyl sebacate, dioctyl sebacate,
butyrolactone, caprolactone, methyl caprolactone, propiolactone,
dioctyl phthalate and the like, ketones such as acetone, methyl
ethyl ketone, methyl propyl kentone, methyl n-butyl ketone,
methyl amyl ketone, diethyl ketone, diisobutyl ketone,
diisopropyl ketone, methyl isoamyl ketone, ethyl amyl ketone,
methyl isobutyl ketone, methyl isopropyl ketone, methyl nonyl
ketone, cyclopentanone, cyclobutanedione, methylcyclohexanone,
- 29 -

CA 02205301 1997-OS-13
acetophenone, diacetone alcohol, mesityl oxide, acrolein,
benzophenone, chlorobenzophenone, dichlorobenzophenone,
difluorobenzophenone, fluorobenzophenone, hydroxybenzophenone,
dihydroxybenzophenone, difluoroterephthalophenone, dichlorotere-
phthalophenone, dihydroxyterephthalophenone and the like,
aldehydes such as acetaldehyde, benzaldehyde, butylaldehyde and
the like, hydrocarbons such as hexane, heptane, octane,
cyclohexane, decane, methyl cyclohexane, tetrahydronaphthalene,
benzene, toluene, xylene, styrene, ethyl benzene, n-propyl
benzene, cyclopentane and the like, halogenated hydrocarbons
such as methyl chloride, methylene chloride, trichloromethane,
carbon tetrachloride, ethyl chloride, ethylidene chloride,
methyl iodide, ethyl iodide, benzene iodide, bromobenzene,
chlorobenzene, dichlorobenzene, trichlorobenzene and the like,
fatty acids and phenols such as formic acid, acetic acid,
butyric acid, malefic acid, propionic acid, acetic anhydride,
propionic anhydride, succinic anhydride, malefic anhydride,
acrylic acid, methacrylic acid, phenol, m-cresol, bisphenol A
and the like, nitrogen compounds such as nitromethane,
nitroethane, nitropropane, nitrooctane, nitrobenzene, methyl-
amine, ethylamine, diethylamine, triethylamine, butylamine,
dibutylamine, tributylamine, amylamine, ethylenediamine, N,N-
dimethyl nitroamine, triethylene tetramine, formamide, N-methyl
formamide, N-ethyl formamide, methyl acetamide, N-ethyl
acetamide, N,N-dimethyl formamide, N,N-dimethylacetamide, N,N-
- 30 -

CA 02205301 1997-OS-13
diethyl acetamide, tetramethyl oxyamide, hexamethyl
phosphorylamide, aniline, dimethyl aniline, acetonitrile,
chloroacetonitrile, n-butyronitrile, benzonitrile, capronitrile,
propionitrile, acrylonitrile, malononitrile, n-valeronitrile,
quinoline, morpholine, N-ethyl morpholine, N-acetyl morpholine,
N-formyl morpholine, a -pyrrolidone, N-methyl-2-pyrrolidone,
pyridine, piperidine, N-acetyl piperidine, N-formyl piperidine,
N-acetyl piperidine, N,N-diacetyl piperazine, hydrazine, phenyl
hydrazine, a -caprolactam and the like, carbonates such as
dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate,
diphenyl carbonate, methyl phenyl carbonate, ethyl phenyl
carbonate and the like, sulfur compounds such as methyl ethyl
sulfone, tetramethylene sulfone, dimethyl sulfide, carbon
disulfide, methyl tetramethylene sulfone, methyl propyl sulfone,
dimethyl sulfone, dimethyl sulfoxide, dimethyl tetramethylene
sulfone, diethyl sulfone, sulfolane, thiophene, dipropyl sulfone,
.~~ ~w..___, __, r
u-~-~Ji1C11y1 sul=one, diziuorodiphenyl sulfone, dichlorodiphenyl
sulfone, dihydroxydiphenyl sulfone and the like, phosphorus
compounds such as dibutylphenyl phosphate, tricresyl phosphate,
triphenyl phosphate, hexamethylphosphoric triamide and the like,
and mixtures thereof.
Of the aforesaid heat stabilizing solvents, particularly
preferred for use are 1,4-butanediol, 1,3-butanediol, ethylene
glycol, diethylene glycol, triethylene glycol, tetraethylene
glycol, propylene glycol, dipropylene glycol, tripropylene
- 31 -

CA 02205301 1997-OS-13
glycol, glycerol, polyethylene glycol, polypropylene glycol,
N,N-dimethyl formamide, N,N-dimethyl acetamide, N-methyl-2-
pyrrolidone and mixtures thereof. If polyethylene glycol or
polypropylene glycol is used as a heat stabilizing solvent
according to the instant invention, each weight average
molecular weight is not particularly limited but ranges
preferably from 100 to 2,000.
The time necessary for the heat treatment of the instant
invention is not especially restricted but is in the range of
preferably 30 seconds to 100 hours, more preferably 1 minute to
50 hours, still more preferably 1 minute to 2 hours.
If the PEEK membrane is under the wet condition of being
immersed in a heat stabilizing solvent, the heat treatment of
the present invention may be carried out in an open system or in
a closed system wherein an autoclave or the like is used, while
if the PEEK membrane is in the wet condition of applying a heat
stabilizing solvent thereto or impregnating the solvent
thereinto, the heat treatment may be performed in an open system
by use of an oven or the like or in a closed system by use of an
autoclave or the like. However, in the open system, the PEEK
membrane is in some cases deformed or damaged on its surface
because of the intense evaporation of the heat stabilizing
solvent during the heat treatment. Therefore, in the open
system in which an oven or the like is used, attention must be
paid so that the PEEK membrane may not deviate from the wet
- 32 -

CA 02205301 1997-OS-13
condition owing to the evaporation of the heat stabilizing
solvent.
Furthermore, when the heat treatment of the present
invention is performed, the atmosphere of the heat stabilizing
solvent may be the air or an inert gas such as nitrogen, argon,
helium or the like. If oxygen in the air has such an influence
that it degrades the water permeability or fractionating
characteristics of the resulting PEEK filtration membrane
because oxygen deteriorates the heat stabilizing solvent during
the heat treatment, it is preferred that the heat treatment is
carried out under an inert gas.
If the heat treatment follows step (D) consecutively, it
is effective that residual low boiling point solvents such as
coagulation liquids, rinse solvents, etc. are removed from the
PEEK filtration membrane prior to the said treatment. Further,
it is preferred that the low boiling point solvents remaining in
the PEEK filtration membrane after step (D) are substituted by a
portion of the heat stabilizing solvent to be used in the heat
treatment. If the said low boiling point solvents remain in the
surface or inner regions of the membrane at the time of the heat
treatment, it is undesirable that the semipermeable membrane is
deformed or damaged in some cases on account of the boiling of
the residual low boiling point solvents.
Furthermore, if the heat treatment is performed
consecutively following step (D), the PEEK filtration membrane
- 33 -

CA 02205301 1997-OS-13
may be impregnated with a high molecular weight compound as
treatment prior to the heat treatment according to necessity.
This tends to result in a smaller difference between the water
permeability of the said membrane before and after the heat
treatment.
Any of the said high molecular weight compounds may be
used without particular restriction if it does not decompose at
temperatures not lower than the glass transition point of PEEK
and particularly at~the temperatures of the heat treatment to be
performed thereafter, has no chemical influence on PEEK and
further can be removed from the PEEK filtration membrane with a
solvent after the heat treatment.
If the heat treatment is carried out according to the
instant invention, the residual heat stabilizing solvent used '
for the heat treatment is normally removed by rinsing after the
heat treatment. As the said rinse solvent, water or an organic
solvent such as an alcohol, acetone or the like is used
preferably and the temperature for rinsing is in the range
between 5 and 120 degrees C. However, it is undesirable that
the deformation of the PEEK membrane and the damage of its
surface tend to take place if the rinse solvent for removing the
residual heat stabilizing solvent boils under reflux or the like.
The rinse step for washing away the residual heat stabilizing
solvent may be omitted, if there is no problem with the solvent
in using the PEEK membrane as a separation membrane.
- 34 -


CA 02205301 1997-OS-13
If the PEEK membrane dries in its inner regions and on its
surface even after the heat treatment of the present invention,
the aforesaid preservation method may be effectively applied
thereto because the water permeability tends to be lowered.
The PEEK membrane of the present invention has an ion
exchange capacity of 0 to 0.5 meq/g. Especially, in order to
enhance its heat and chemical resistance, the ion exchange
capacity should range preferably from 0.005 to 0.3 meg/g and
more preferably from 0.005 to 0.2 meq/g. To enhance its
hydrophilic property and fouling resistance, it is preferred
that the ion exchange capacity is in the range of 0.1 to 0.5
meq/g.
The aforesaid heat treatment enhances the crystallinity of
the PEEK membrane prepared according to the instant invention
and as a result, may further improve the heat and chemical
resistance thereof. If the heat and chemical resistance are
required at a temperature exceeding 100 degrees C, the
crystallinity is preferably at least 10 percent by weight, more
preferably at least 20 percent by weight, and still more
preferably at least 25 percent by weight, though depending upon
the application field of the PEEK membrane. The crystallinity
of the PEEK membrane in the present invention is expressed by
the ratio of the crystallized component to the total of the PEEK
membrane on a weight basis and is measured according to the
wide-angle X-ray diffractometry reported by Blundell and Osborn
- 35 -

CA 02205301 1997-OS-13
(Polymer, 24, 953, 1983).
The PEEK membrane obtained according to the present
invention is excellent in chemical resistance despite being
manufactured by using sulfuric acid and, for example, can be
used in an acid or alkaline solvent or even in a polar organic
solvent. If the crystallinity of the PEEK membrane is increased
by the aforesaid heat treatment, not only is the chemical
resistance further improved but also the mechanical strength,
for example, tensile strength and bursting strength are enhanced
remarkably. Furthermore, regarding heat resistance, the PEEK
membrane thus treated has excellent heat stability in water of
100 degrees C and even in water having temperatures exceeding
150 degrees C.
Because membrane formation is performed with the use of
concentrated sulfuric acid highly capable of dissolving PEEK, it
is possible to control the fractionating and water permeability
characteristics throughout a wide range and to prepare both an
asymmetric membrane having the surface and inner regions with
differing pore sizes and a symmetric membrane having pores
uniform in size throughout the whole thereof, depending upon the
composition of the membrane' forming stock solution and the
coagulation conditions thereof.
The PEEK membrane obtained according to the present
invention may contain a hygroscopic polymer such as polyvinyl
pyrrolidone or the like or further crosslink therewith to such
- 36 -

CA 02205301 1997-OS-13
an extent that it has no influence on the properties of the PEEK
membrane such as heat resistance and the like.
The form of the PEEK membrane prepared according to the
present invention is not especially restricted but is preferably
that of a hollow fiber. In this case, the wall thickness of the
hollow fiber is not particularly restricted but ranges generally
from 5 to 3, 000 um and particularly preferably from 10 to l, 000
um. The outside diameter of the said hollow fiber is not
especially limited, but ranges generally from 10 to 10,000 um
and particularly preferably from 300 to 5,000 um.
Best Mode For Carrying Out The Invention
Hereinbelow, the present invention will be described in
more detail with reference to the following examples, but they
should not be construed to limit the scope of the present
invention.
First, descriptions will be given on the measuring methods
to be adopted in the following examples and comparative examples.
(1) Method of measuring ion exchange capacity
Five grams of sodium chloride is dissolved in distilled
water so as to obtain 100 m~ of an aqueous sodium chloride
solution, in which 0.1 g of a PEEK membrane is immersed. After
agitation for two hours at room temperature, the membrane is
taken out therefrom and the said sodium chloride solution is
titrated with a 0.025 N aqueous sodium hydroxide solution. On
the other hand, the membrane thus taken out is immersed in 50 me
- 37 -

CA 02205301 1997-OS-13
of 0.1 N sulfuric acid and allowed to stand for two hours at
room temperature. The said membrane is taken out from the
sulfuric acid and is dried under vacuum at 50 degrees C for ca.
24 hours after being washed with pure water until it is
neutralized in order to measure the weight of the membrane.
Based upon the titer and the weight of the membrane obtained in
the above-mentioned method, the ion exchange capacity of the
PEEK membrane is calculated according to the following formula:
ion exchange capacity (meq/g)
=titer (m~) x 0.025 - membrane weight (g)
Provided that the ion exchange capacity of the membrane is
less than 0.1 meq/g, the measurement is made by increasing the
weight of the membrane or the sodium ion absorbed in the above-
mentioned method is measured by means of absorption spectroscopy.
(2) Water permeability
If the form of the membrane is that of a flat-sheet
membrane, the flat-sheet membrane is placed in a plastic filter
holder (Trade name: PP-25, a product of Advantec Toyo, Co.,
Ltd.) and 25 degree C distilled water is passed through the
membrane at a pressure of 1 kg/cm2 from the side exposed to a
coagulation liquid at the time of membrane formation to measure
the volume of the distilled water passed therethrough for 20
minutes. Water permeability is expressed as flux by calculating
- 38 -

CA 02205301 1997-OS-13
the said volume in terms of 8/m2~hr~kg/cmz. Further, if the form
of the membrane is that of a hollow fiber, 25 degree C distilled
water is injected at a pressure of 1 kg/cm2 into the bore of a
30-cm long hollow fiber whose one end is sealed to measure the
volume of the distilled water permeated through the wall of the
hollow fiber for 20 minutes. Water permeability is expressed as
flux by calculating the said volume in terms of 2/m2~hr~kg/cm2.
(3) Method of measuring the hollow fiber membrane rejection
ratio of dextran molecules
Dextran {a product of Pharmacia) having a weight average
molecular weight of 10,000 is added to distilled water to
prepare a feed dextran solution so that it may have a
concentration of 0.5 percent by weight. The said feed solution
is injected through the bore of a hollow fiber membrane having a
length of 30 cm at a temperature of 25 degrees C, a linear rate
of 1 m/sec. and an average filtration pressure of 1 kg/cmz for
minutes to obtain a filtrate through the wa i i of +ho h~" ~r.,
_--~7-- ~--~ .....v.a_~ vi a..ilG tiVllVW
fiber membrane. The rejection ratio of the hollow fiber
membrane is obtained from the following formula:
rejection ratio (a) - {1 - C/Co) x 100
wherein C and Co indicate the respective concentrations of the
obtained filtrate and the feed dextran solution.
- 39 -

CA 02205301 1997-OS-13
(4) Method of measuring the hollow fiber membrane rejection
ratio of polystyrene latex particles
Polystyrene latex (a product of Seradyn, Inc.) having a
particle size of 0.212 um is added to distilled water to prepare
a feed suspension so that it may have a concentration of 200 ppm.
The rejection ratio is obtained according to the same filtration
and calculation methods as in the aforesaid dextran case.
(5) Method of measuring the crystallinity of hollow fiber
membrane
By use of X-ray diffraction equipment (MXP-18, a product
of MAC Science Co.,Ltd.), the X-ray obtained from a Cu target
with an acceleration voltage of 50 kV and acceleration current
of 200 mA is made monochromic with an Ni monochrometer.
Specimens are placed on a fiber sample table and subjected to
measurement by means of penetration. The scattered X-ray from
each specimen is scanned in the range of 12° to 32° and 50
points are adopted per 1° and the measurement is performed for
1.2 seconds per point.
Example 1
Ten grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREX
PEEK 4506, particle size: ca. 4 mm) was added to 90 grams of
97.5 ~ concentrated sulfuric acid (a product of Kanto Chemical
Co., Inc.) at 17 degrees C and was uniformly dissolved therein
in a closed system while the temperature was being kept at 17
- 40 -

CA 02205301 1997-OS-13
degrees C to prepare a membrane forming stock solution. The
stock solution was deaerated under vacuum while the temperature
was being kept at 17 degrees C. The time required for the
dissolution and deaeration totaled 4 hours.
The membrane forming stock solution was cooled to 5
degrees C immediately after the deaeration and was preserved,
being allowed to stand for 40 hours.
The stock solution thus obtained was applied to a glass
plate in a thickness of 100 um and was consecutively immersed
and coagulated in 23 degree C distilled water, in which it was
allowed to stand for 5 minutes. The resulting membrane was
thereafter taken out from the water, immersed in running water
for 1 hour and soaked in ethanol for 2 hours to wash away
residual sulfuric acid therefrom.
The PEEK flat-sheet membrane thus obtained had an ion
exchange capacity of 0.09 meq/g and was not sulfonated
substantially. The flux of the membrane was 155 ~ /m2~ hr~kg/cmz .
As a result of observing the surface and cross-section of the
membrane at a magnification of 10,000 times with a scanning
electron microscope, it was found that the membrane was
asymmetrical in structure, having a surface with no open pores,
a tight skin layer in the vicinity of the surface and internal
voids which became larger gradually as they went inwards.
- 41 -

CA 02205301 1997-OS-13
Example 2
Ten grams of PEEK comprising the repeating units
represented by Formula (1} of Group 1 (a product of ICI, VICTREX
PEEK 450G) ground into particles of ca. 0.3 mm in diameter was
added to 90 grams of 97.5 a concentrated sulfuric acid (a
product of Kanto Chemical Co., Inc.) at 10 degrees C and was
uniformly dissolved therein in a closed system while the
temperature was being kept at 10 degrees C to prepare a membrane
forming stock solution. The stock solution was deaerated under
vacuum while the temperature was being kept at 10 degrees C.
The time required for the dissolution and deaeration totaled 4
hours.
The membrane forming stock solution was cooled to 5
degrees C immediately after the deaeration and was allowed to be
left for 40 hours.
The stock solution thus prepared was applied to a glass
plate to provide a thickness of 100 um on the glass plate and
was consecutively immersed and coagulated in 23 degree C
distilled water, in which it was allowed to stand for 5 minutes.
The resulting membrane was thereafter taken out from the water,
immersed in running water for 1 hour and soaked in ethanol for 2
hours to wash away the residual sulfuric acid remaining in the
membrane.
The PEEK flat-sheet membrane thus obtained had an ion
exchange capacity of 0.07 meq/g and was not sulfonated
- 42 -

CA 02205301 1997-OS-13
substantially. The flux of the membrane was 170 a /m2~ hr~kg/cm2 .
Further, as a result of observing the surface and cross-section
of the membrane at a magnification of 10,000 times with a
scanning electron microscope, it was found that the membrane was
asymmetrical in structure, having a surface with no open pores,
a tight skin layer in the neighborhood of the surface and
internal voids which became larger gradually as they went
inwards.
Example 3
Ten grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREX
PEEK 450G) ground into particles of ca. 1 mm in diameter was
added to 90 grams of 94.5 ~ concentrated sulfuric acid (a
product of Kanto Chemical Co., Inc.) at 18 degrees C and was
uniformly dissolved therein in a closed system while the
temperature was being kept at 10 degrees C to prepare a membrane
forming stock solution. The stock solution was deaerated under
vacuum while the temperature was being kept at 10 degrees C.
The time required for the dissolution and deaeration totaled 5
hours.
The membrane forming stock solution was cooled to 5
degrees C immediately after the deaeration and was allowed to
stand for 50 hours.
- 43 -

CA 02205301 1997-OS-13
The stock solution thus prepared was applied to a glass
plate to provide a thickness of 100 um on the glass plate and
was consecutively immersed and coagulated in 60 o sulfuric acid
of 23 degrees C, in which it was allowed to be left for 5
minutes. The resulting membrane was thereafter taken out from
the sulfuric acid, immersed in running water for 1 hour and
soaked in ethanol for 2 hours to wash away the sulfuric acid
remaining in the membrane. '
The PEEK flat-sheet membrane thus obtained had an ion
exchange capacity of 0.04 meq/g and was not sulfonated
substantially. The flux of the membrane was 350 ~/m2~hr~kg/cm2 .
Further, as a result of observing the surface and cross-section
of the membrane at a magnification of 10,000 times with a
scanning electron microscope, it was found that the membrane was
asymmetrical in structure, having a surface with no open pores,
a tight skin layer in the vicinity of the surface and internal
voids which became larger gradually as they went inwards.
Example 4
Ten grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREx
PEEK 450G) ground into particles of ca. 0.3 mm in diameter was
added to 90 grams of 97.5 o concentrated sulfuric acid (a
product of Kanto Chemical Co., Inc.) at 6 degrees C, and 3 grams
of polyvinyl pyrrolidone (weight average molecular weight:
10,000, a product of Kishida Chemical Co., Ztd.) was further
- 44 -

CA 02205301 1997-OS-13
added thereto. They were uniformly dissolved therein in a
closed system while the temperature was being kept at 6 degrees
C to prepare a membrane forming stock solution. The stock
solution was deaerated under vacuum while the temperature was
being kept at 6 degrees C. The time required for the
dissolution and deaeration totaled 10 hours.
The membrane forming stock solution was cooled to 3
degrees C immediately after the deaeration and was allowed to
stand for 20 days.
The stock solution thus prepared was applied to a glass
plate to provide a thickness of 100 um thereon and immediately
immersed and coagulated in 60 °s sulfuric acid of 23 degrees C,
in which it was allowed to be left for 10 minutes therein. The
resulting membrane was thereafter taken out from the sulfuric
acid, immersed in running water for 1 hour and soaked in ethanol
for 2 hours to wash away the sulfuric acid remaining in the
membrane. Further, by immersing the membrane in a 25°C aqueous
solution of 3,000 ppm sodium hypochlorite for 20 hours, residual
polyvinyl pyrrolidone was removed therefrom.
The PEEK flat-sheet membrane thus obtained had an ion
exchange capacity of 0.04 meq/g and was not sulfonated
substantially. The flux of the membrane was 980 a /m2 ~hr ~ kg/cm2.
Further, as a result of observing the surface and cross-section
of the membrane at a magnification of 10,000 times with a
scanning electron microscope, it was found that the membrane was
- 45 -

CA 02205301 1997-OS-13
asymmetrical in structure, having a surface with no open pores,
a tight skin layer in the neighborhood of the surface and
internal voids which became larger gradually as they went
inwards.
Comparative example 1
Ten grams of PEEK comprising the repeating units
represented by Formula (1} of Group 1 (a product of ICI, VICTREX
PEEK 4506, particle size: ca. 4 mm) was added to 90 grams of
97.5 % concentrated sulfuric acid (a product of Kanto Chemical
Co., Inc.) at 25 degrees C and was uniformly dissolved therein
in a closed system while the temperature was being kept at 25
degrees C to prepare a membrane forming stock solution. The
stock solution was deaerated under vacuum while the temperature
was being kept at 25 degrees C. The time required for the
dissolution and deaeration totaled 4 hours.
After the deaeration, the membrane forming stock solution
was allowed to stand for 20 hours, while it was being kept at a
temperature of 25 degrees C.
The stock solution thus prepared was applied to a glass
plate to provide a thickness of 100 um on the glass plate and
immediately immersed and coagulated in 23 degree C distilled
water, in which it was allowed to be left for 5 minutes. The
resulting membrane was thereafter taken out from the water,
immersed in running water for 1 hour and soaked in ethanol for 2
hours to wash away the sulfuric acid remaining in the membrane.
- 46 -

CA 02205301 1997-OS-13
The membrane thus obtained swelled when immersed in
ethanol. Further, the said membrane was swelled and intensively
deformed in boiling water.
The PEEK flat-sheet membrane obtained in this comparative
example had an ion exchange capacity of 0.7 meq/g and was
sulfonated substantially.
Comparative example 2
Ten grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREX
PEEK 4506, particle size: ca. 4 mm) was added to 90 grams of
97.5 % concentrated sulfuric acid (a product of Kanto Chemical
Co., Inc.) at 25 degrees C and was uniformly dissolved therein
in a closed system while the temperature was being kept at 25
degrees C to prepare a membrane forming stock solution. The
stock solution was deaerated under vacuum while the temperature
was being kept at 25 degrees C. The time required for the
dissolution and deaeration totaled 4 hours.
After the deaeration, the membrane forming stock solution
was allowed to stand for 20 days while the stock solution was
being kept at 18 degrees C.
The stock solution thus prepared was applied to a glass
plate to provide a thickness of 100 um on the glass plate and
was immediately immersed and coagulated in 23 degree C distilled
water, in which it was allowed to be left therein for 5 minutes.
The resulting membrane was then taken out from the water and
- 47 -


CA 02205301 1997-OS-13
immersed in running water for 1 hour.
The obtained membrane had an ion exchange capacity of 1.4
meq/g and was sulfonated substantially. As soon as the said
membrane was immersed and washed in ethanol, it dissolved
therein.
Example 5
One hundred grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREX
PEEK 450G) ground into particles of ca. 0.3 mm in diameter was
added to 900 grams of 97.5 ~ concentrated sulfuric acid (a
product of Kanto Chemical Co., Inc.) at 10 degrees C and was
uniformly dissolved therein in a closed system while the
temperature was being kept at 10 degrees C to prepare a membrane
forming stock solution. The stock solution was deaerated under
vacuum while the temperature was being kept at 10 degrees C.
The time required for the dissolution and deaeration totaled 10
hours.
Immediately after the deaeration, the membrane forming
stock solution was cooled to 6 degrees C.
The stock solution, of which the temperature was kept at 6
degrees C, was extruded through a tube-in-orifice type spinneret
for hollow fiber spinning at a flow rate of 6 m2/min., while 25°C
water was being injected as a coagulant through the bore at the
same time. The solution thus extruded was immersed in a 24 °C
water bath underlaid 9 cm below the spinneret and was wound
- 48 -


CA 02205301 1997-OS-13
after coagulation. About 80 minutes was required for the
spinning from the beginning to the end.
The wound hollow fiber membrane was washed by immersing it
in 25 °C running water for 10 hours and then in 25 °C ethanol
for
hours.
The portion of the hollow fiber membrane wound immediately
after the beginning of the spinning had an ion exchange capacity
of 0.02 meq/g, while the other portion of the hollow fiber
membrane wound in the neighborhood of the end of the spinning
had also an ion exchange capacity of 0.02 meq/g. Thus, the PEEK
hollow fiber membrane could be obtained by spinning without
substantial sulfonation.
The resulting hollow fiber membrane was heat treated,
without being dried, in 90 degree C triethylene glycol for 1
hour and further in 200 degree C triethylene glycol for 1 hour.
After this treatment, the PEEK hollow fiber membrane was
immersed in 25 degree C ethanol to remove residual triethylene
glycol therefrom and was kept in water.
The PEEK hollow fiber membrane thus obtained had a flux of
48 2 /m2 ~ hr ~ kg/cm2, crystallinity of 24 percent measured by the
wide-angle X-ray diffraction analysis and a dextran rejection
ratio of 92 percent.
The said membrane was excellent in heat resistance without
showing any change in appearance and water permeability even if
immersed in 130 degree C water for 10 hours.
- 49 -

CA 02205301 1997-OS-13
Example 6
One hundred grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREX
PEEK 450G) ground into particles of ca. 0.3 mm in diameter was
added to 900 grams of 97.5 o concentrated sulfuric acid (a
product of Kanto Chemical Co., Inc.) at 8 degrees C, and 30
grams of polyvinyl pyrrolidone {weight average molecular weight:
10,000, a product of Kishida Chemical Co., Ztd.) was further
added thereto. They were uniformly dissolved therein in a
closed system while the temperature was being kept at 8 degrees
C to prepare a membrane forming stock solution. The stock
solution was deaerated under vacuum while the temperature was
being kept at 8 degrees C. The time required for the
dissolution and deaeration totaled 15 hours.
Immediately after the deaeration, the membrane forming
stock solution was cooled to 3 degrees C.
The membrane forming stock solution, of which the
temperature was kept at 3 degrees C, was extruded through a
tube-in-orifice type spinneret at a flow rate of 6 m8 /min.,
while 25°C water was being injected as an inside coagulant into
the bore at the same time. The stock solution thus extruded was
immersed in a 24°C water bath underlaid 9 cm below the spinneret
and was wound after it coagulated. About 90 minutes was
required for spinning from the beginning to the end.
- 50 -


CA 02205301 1997-OS-13
The wound hollow fiber membrane was washed by immersing it
in 25 °C running water for 10 hours and then in 25 °C ethanol
for
hours. It was further rinsed by immersing it in a 26°C
aqueous solution of sodium hypochorite having a concentration of
3,000 ppm for 20 hours.
The portion of the hollow fiber membrane wound immediately
after the beginning of the spinning had an ion exchange capacity
of 0.01 meq/g, while the other portion of the hollow fiber
membrane wound near the end of the spinning also had an ion
_,~.._
e:x~:ma.tige CapaClty Of 0.01 meq/g. Thus, the PEEK hollow fiber
membrane could be spun without being sulfonated substantially.
The obtained hollow fiber membrane, without being dried,
was heat treated in 90°C triethylene glycol for 1 hour and
further heat treated in 200°C triethylene glycol for 1 hour.
After this treatment, the PEEK hollow fiber membrane was
immersed in 25°C ethanol to remove residual triethylene glycol
therefrom and was thereafter kept in water.
The PEEK hollow fiber membrane thus obtained had a flux of
80 a /m2 ~ hr - kg/cm2, crystallinity of 24 percent measured by the
wide-angle X-ray diffraction analysis and a dextran rejection
ratio of 92 percent.
Measured under the condition of a 5 cm distance between
grips, 50 mm/min. grip separation speed and 25 degrees C, the
- 51 -


CA 02205301 1997-OS-13
tensile strength of the PEEK hollow fiber membrane was found to
be 68 kg/cm2.
Example 7
One hundred grams of PEEK comprising the repeating units
represented by Formula (1) of Group 1 (a product of ICI, VICTREX
PEEK 450G) ground into particles of ca. 0.3 mm in diameter was
added to 900 grams of 97.5 ~ concentrated sulfuric acid (a
product of Kanto Chemical Co., Inc.) at 10 degrees C, and 30
grams of polyvinyl pyrrolidone (weight average molecular weight:
10,000, a product of Kishida Chemical Co., Ltd.) was further
added thereto. They were uniformly dissolved therein in a
closed system while keeping the temperature at 10 degrees C to
prepare a membrane forming stock solution. The stock solution
was deaerated under vacuum while keeping the temperature at 10
degrees C. The time required for the dissolution and deaeration
totaled 10 hours.
Immediately after the deaeration, the membrane forming
stock solution was cooled to 3 degrees C.
The stock solution, of which the temperature was kept at 3
degrees C, was extruded through a tube-in-orifice type spinneret
at a flow rate of 6 m$/min., while passing 25°C 50~ sulfuric acid
as an inside coagulant through the bore. The stock solution
thus extruded was immersed in a 24 °C water bath underlaid 5 cm
below the spinneret and was wound after it coagulated. About 90
- 52 -


CA 02205301 1997-OS-13
minutes was required for spinning from the beginning to the end.
The wound hollow fiber membrane was washed by immersing it
in 25°C running water for 10 hours and further immersing in 25°C
ethanol for 10 hours. The membrane was thereafter rinsed by
immersing it in a 26°C aqueous solution of sodium hypochorite
having a concentration of 3,000 ppm for 20 hours.
The portion of the hollow fiber membrane wound immediately
after the beginning of the spinning had an ion exchange capacity
of 0.02 meq/g, while the other portion of the hollow fiber
membrane wound near the end of the spinning also had an ion
exchange capacity of 0.02 meq/g. Therefore, the PEEK hollow
fiber membrane could be spun without being sulfonated
substantially.
The PEEK hollow fiber membrane thus obtained had a flux of
240 e/mz~hr~kg/cm2 and a dextran rejection ratio of 72 percent.
Comparative example 3
The membrane forming stock solution prepared and kept in
the same manner as in Comparative example 1 was spun into a
hollow fiber membrane in the same way as in Example 7.
The obtained hollow fiber membrane had an ion exchange
capacity of 0.84 meq/g. Its tensile strength was measured as in
Example 6 and resulted in a value of 21 kg/cm2. The membrane
was clearly inferior in tensile strength to that obtained in
Example 6.
- 53 -

CA 02205301 1997-OS-13
Industrial Applicability
In accordance with the present invention it is possible to
advantageously obtain a polyether ether ketone membrane by using
sulfuric acid which is easy to handle and available at low
prices generally from a commercial viewpoint, instead of using
organic acids or hydrofluoric acid in its preparation. The PEEK
membrane obtained by the production process of the present
invention is excellent in mechanical strength and heat and
chemical resistance and has low elution characteristics.
Further, the use of sulfuric acid which is highly effective in
dissolving PEEK, makes it possible to control membrane
performance throughout a wide range, so that a membrane having
an excellent balance of water permeability and fractionating
characteristics can be obtained.
For the above reasons, the PEEK membrane of the present
invention may be advantageously employed for filtration in the
preparation of ultrapure .water for semiconductors in the
electronic industry and for filtration in the fields of medical
appliances, pharmaceuticals and foods. Further, the PEEK
membrane of the present invention may also be advantageously
employed for severe use in stable filtration for a long term at
high temperatures exceeding 100 degrees C, if the crystallinity
of the membrane is heightened by the heat treatment wherein a
heat stabilizing solvent is used.
- 54 -

Representative Drawing

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Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date 2000-07-25
(86) PCT Filing Date 1995-12-05
(87) PCT Publication Date 1996-06-13
(85) National Entry 1997-05-13
Examination Requested 1997-05-13
(45) Issued 2000-07-25
Deemed Expired 2009-12-07

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Request for Examination $400.00 1997-05-13
Registration of a document - section 124 $100.00 1997-05-13
Application Fee $300.00 1997-05-13
Maintenance Fee - Application - New Act 2 1997-12-05 $100.00 1997-05-13
Maintenance Fee - Application - New Act 3 1998-12-07 $100.00 1998-08-26
Maintenance Fee - Application - New Act 4 1999-12-06 $100.00 1999-05-27
Final Fee $300.00 2000-04-18
Maintenance Fee - Application - New Act 5 2000-12-05 $150.00 2000-05-19
Maintenance Fee - Patent - New Act 6 2001-12-05 $150.00 2001-11-19
Maintenance Fee - Patent - New Act 7 2002-12-05 $150.00 2002-11-19
Maintenance Fee - Patent - New Act 8 2003-12-05 $150.00 2003-11-17
Maintenance Fee - Patent - New Act 9 2004-12-06 $200.00 2004-11-08
Maintenance Fee - Patent - New Act 10 2005-12-05 $250.00 2005-11-08
Maintenance Fee - Patent - New Act 11 2006-12-05 $250.00 2006-11-08
Maintenance Fee - Patent - New Act 12 2007-12-05 $250.00 2007-11-09
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
ASAHI KASEI KOGYO KABUSHIKI KAISHA
Past Owners on Record
HACHIYA, HIROSHI
SHIMODA, TERUYOSHI
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Cover Page 1997-07-23 1 41
Claims 1997-05-13 2 40
Description 1997-05-13 54 2,060
Abstract 1997-05-13 1 14
Claims 1997-11-12 2 54
Cover Page 2000-07-18 1 30
Correspondence 2000-04-18 1 33
Fees 1998-08-26 1 50
Assignment 1997-05-13 6 115
PCT 1997-05-13 7 124
Fees 1999-05-27 1 46
Fees 2000-05-19 1 41