U.S. patent application number 15/377265 was filed with the patent office on 2017-03-30 for polymer composition and porous membrane.
This patent application is currently assigned to Mitsubishi Rayon Co., Ltd.. The applicant listed for this patent is Mitsubishi Rayon Co., Ltd.. Invention is credited to Shingo Hikita, Tetsuya Noda.
Application Number | 20170087520 15/377265 |
Document ID | / |
Family ID | 50978548 |
Filed Date | 2017-03-30 |
United States Patent
Application |
20170087520 |
Kind Code |
A1 |
Hikita; Shingo ; et
al. |
March 30, 2017 |
Polymer Composition and Porous Membrane
Abstract
A polymer composition containing a polymer (B) obtained by
polymerizing a monomer composition containing: a methacrylic acid
ester macromonomer (b1) represented by the following formula (1);
and another monomer (b2). Also, a porous membrane formed from a
membrane forming polymer (A) and the aforementioned polymer
composition. ##STR00001##
Inventors: |
Hikita; Shingo; (Hiroshima,
JP) ; Noda; Tetsuya; (Hiroshima, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Rayon Co., Ltd. |
Tokyo |
|
JP |
|
|
Assignee: |
Mitsubishi Rayon Co., Ltd.
Tokyo
JP
|
Family ID: |
50978548 |
Appl. No.: |
15/377265 |
Filed: |
December 13, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14652506 |
Jun 16, 2015 |
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PCT/JP2013/084318 |
Dec 20, 2013 |
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15377265 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 61/145 20130101;
C08J 2451/00 20130101; C02F 1/444 20130101; C08L 27/16 20130101;
B01D 71/40 20130101; B01D 2323/02 20130101; C08F 290/04 20130101;
C08J 5/18 20130101; C08J 9/28 20130101; B01D 71/80 20130101; H01M
10/0525 20130101; C08J 2205/042 20130101; Y02E 60/10 20130101; B01D
69/08 20130101; C08L 101/00 20130101; H01M 2300/0085 20130101; B01D
71/34 20130101; B01D 61/14 20130101; C08L 55/00 20130101; H01M
2/1653 20130101; B01D 69/02 20130101; B01D 2325/36 20130101; H01M
10/0565 20130101; C08J 9/0061 20130101; B01D 71/32 20130101; C08J
2201/0544 20130101; C09D 127/16 20130101; B01D 2325/02 20130101;
C08J 2327/16 20130101; B01D 67/0006 20130101; C09D 127/16 20130101;
C08L 33/06 20130101 |
International
Class: |
B01D 71/80 20060101
B01D071/80; B01D 71/34 20060101 B01D071/34; B01D 61/14 20060101
B01D061/14; B01D 69/08 20060101 B01D069/08; C08J 9/28 20060101
C08J009/28; H01M 10/0525 20060101 H01M010/0525; H01M 2/16 20060101
H01M002/16; H01M 10/0565 20060101 H01M010/0565; C08L 27/16 20060101
C08L027/16; C08J 9/00 20060101 C08J009/00; B01D 71/40 20060101
B01D071/40; C02F 1/44 20060101 C02F001/44 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2012 |
JP |
2012-278592 |
Feb 19, 2013 |
JP |
2013-029966 |
Claims
1. A polymer composition comprising: a membrane forming polymer
(A); and a polymer (B) obtained by polymerizing a monomer
composition containing a methacrylic acid ester macromonomer (b1)
represented by the following Formula (1) ##STR00004## and another
monomer (b2), where R and R.sup.1 to R.sup.n of Formula (1) each
independently represents a hydrogen atom, an alkyl group, a
cycloalkyl group, an aryl group or a heterocyclic group, Z is a
terminal group, and n is an integer from 2 to 10,000.
2. The polymer composition according to claim 1, further comprising
a membrane forming polymer (A).
3. The polymer composition according to claim 2, wherein the
membrane forming polymer (A) is a fluorine-containing polymer.
4. The polymer composition according to claim 1, wherein the other
monomer (b2) is (meth)acrylic acid or a (meth)acrylate.
5. The polymer composition according to claim 1, wherein a contact
angle of pure water on an outer surface of a porous membrane formed
from the polymer composition is 75.degree. or less.
6.-10. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to a polymer composition and a
porous membrane.
[0002] This application is based upon and claims the benefit of
priority of the prior Japanese Patent Application No. 2012-278592,
filed in the Japan Patent Office on Dec. 20, 2012, and the prior
Japanese Patent Application No. 2013-029966, filed in the Japan
Patent Office on Feb. 19, 2013, the entire contents of which are
incorporated herein by reference.
BACKGROUND ART
[0003] Porous membranes are utilized in various fields such as a
water treatment field including drinking water production, water
purification treatment, and waste water treatment. In recent years,
simplified manufacturing process is desired in addition to the
membrane performance such as high fractionation performance or
hydrophilicity.
[0004] As a porous membrane, a polymer membrane containing a
hydrophobic matrix polymer such as polyvinylidene fluoride and an
amphiphilic block copolymer has been proposed in Patent Document 1.
However, the porous membrane described in Patent Document 1 has a
bubble point diameter of about from 122 to 198 nm and thus the
fractionation performance thereof cannot be said to be sufficient
for an ultrafiltration application. In addition, the block
copolymer used in Patent Document 1 is produced by a controlled
radical polymerization method such as nitroxide-mediated
polymerization (NMP), thus the monomer is required to be removed
after the polymerization, and as a result, the porous membrane
cannot be said to be cost-effective.
CITATION LIST
Patent Document
[0005] Patent Document 1: JP 2012-506,772 W
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0006] An object of the invention is to provide a polymer
composition and a porous membrane suitable for obtaining a membrane
exhibiting favorable fractionation performance and high water
permeability by the use of a polymer easily obtained by a usual
radical polymerization.
Means for Solving Problem
[0007] The above problem is solved by the following inventions [1]
to [10].
[0008] [1] A polymer composition including a polymer (B) obtained
by polymerizing a monomer composition containing a methacrylic acid
ester macromonomer (b1) represented by the following Formula (1)
(hereinafter, referred to as macromonomer (b1)) and another monomer
(b2).
##STR00002##
[0009] In Formula (1), R and R.sup.1 to R.sup.n each independently
represent a hydrogen atom, an alkyl group, a cycloalkyl group, an
aryl group or a heterocyclic group,
[0010] Z is a terminal group, and
[0011] n is an integer from 2 to 10,000.
[0012] [2] The polymer composition according to [1], further
including a membrane forming polymer (A).
[0013] [3] The polymer composition according to [2], in which the
membrane forming polymer (A) is a fluorine-containing polymer.
[0014] [4] The polymer composition according to any one of [1] to
[3], in which the other monomer (b2) is (meth)acrylic acid or a
(meth)acrylate.
[0015] [5] The polymer composition according to any one of [1] to
[4], in which a contact angle of pure water on an outer surface of
a porous membrane formed from the polymer composition is 75.degree.
or less.
[0016] [6] A porous membrane formed from a resin composition
containing:
[0017] a membrane forming polymer (A); and
[0018] a polymer (B) obtained by polymerizing a monomer composition
containing a methacrylic acid ester macromonomer (b1) represented
by the following Formula (1) and another monomer (b2).
##STR00003##
[0019] In Formula (1), R and R.sup.1 to R.sup.n each independently
represent a hydrogen atom, an alkyl group, a cycloalkyl group, an
aryl group or a heterocyclic group,
[0020] Z is a terminal group, and
[0021] n is an integer from 2 to 10,000.
[0022] [7] The porous membrane according to [6], in which the
membrane forming polymer (A) is a fluorine-containing polymer.
[0023] [8] The porous membrane according to [6] or [7], in which a
contact angle of pure water on an outer surface of the porous
membrane is 75.degree. or less.
[0024] [9] The porous membrane according to any one of [6] to [8],
in which the porous membrane includes pores having an average pore
size of 500 nm or less.
[0025] [10] The porous membrane according to any one of [6] to [8],
in which the porous membrane includes pores having an average pore
size of 120 nm or less.
Effect of the Invention
[0026] According to the invention, it is possible to obtain a
polymer composition and a porous membrane suitable for obtaining a
membrane exhibiting favorable fractionation performance and high
water permeability by using a polymer easily obtained by a usual
radical polymerization.
[0027] In addition, the polymer composition and the porous membrane
of the invention exhibit the above performance, and thus the
application thereof is not limited to the water treatment field but
they are suitable for a support of an electrolyte solution, in
particular, for a support that is swollen with a lithium ion
electrolyte solution in a lithium ion battery.
MODE(S) FOR CARRYING OUT THE INVENTION
[0028] <Membrane Forming Polymer (A)>
[0029] A membrane forming polymer (A) may be contained in the
polymer composition according to the first aspect of the invention
and is one of the constituents of the porous membrane according to
the second aspect of the invention.
[0030] The membrane forming polymer (A) is used for maintaining the
structure of the polymer composition and the porous membrane of the
invention, and the composition of the membrane forming polymer (A)
can be selected according to the properties required to the polymer
composition and the porous membrane.
[0031] In a case in which chemical resistance, oxidative
deterioration resistance, and heat resistance are required,
examples of the membrane forming polymer (A) may include a
fluorine-containing polymer such as polyvinylidene fluoride (PVDF),
PVDF-co-hexafluoropropylene (HFP),
ethylene-co-chlorotrifluoroethylene (ECTFE), polyvinyl fluoride, or
polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC),
polyethylene, polypropylene, polystyrene, a polystyrene derivative,
a polyamide, a polyurethane, a polycarbonate, a polysulfone, a
polyethersulfone, and cellulose acetate. Among these, a
fluorine-containing polymer such as polyvinylidene fluoride (PVDF),
PVDF-co-hexafluoropropylene (HFP),
ethylene-co-chlorotrifluoroethylene (ECTFE), polyvinyl fluoride, or
polytetrafluoroethylene (PTFE) is preferred from the viewpoint of
chemical resistance and oxidative deterioration resistance of the
polymer composition and the porous membrane. Among these, PVDF is
preferred from the viewpoint of oxidative deterioration resistance
and mechanical durability of the polymer composition and the porous
membrane.
[0032] The membrane forming polymer (A) can be used singly or in
combination of two or more kinds thereof.
[0033] The membrane forming polymer (A) is preferably a polymer
that is soluble in a solvent (C2) to be described later and does
not dissolve in pure water.
[0034] Among the polymers described above, PVDF is preferred from
the viewpoint of compatibility with a polymer (B) and the solvent
(C2) to be described later, chemical resistance, and heat
resistance.
[0035] The mass average molecular weight (hereinafter, referred to
as "Mw") of the membrane forming polymer (A) is preferably from
100,000 to 2,000,000. The mechanical strength of the polymer
composition and the porous membrane of the invention tends to be
favorable when the Mw is 100,000 or more, and the solubility in the
solvent (C2) tends to be favorable when the Mw is 2,000,000 or
less. The Mw is more preferably 300,000 or more, and the Mw is more
preferably 1,500,000 or less. More specifically, the mass average
molecular weight of the membrane forming polymer (A) is more
preferably from 300,000 to 1,500,000, even more preferably from
400,000 to 1,000,000, and particularly preferably from 500,000 to
700,000.
[0036] Incidentally, in the present specification, the Mw adopts
the mass average molecular weight in terms of polystyrene by GPC
(gel permeation chromatography).
[0037] Incidentally, in the case of using those which have the Mw
described above as the membrane forming polymer (A), it is possible
to mix those having different Mw to be used as the membrane forming
polymer (A) having a predetermined Mw.
[0038] <Macromonomer (b1)>
[0039] The macromonomer (b1) is one of the constituents of the
polymer (B) contained in the polymer composition and the porous
membrane of the invention.
[0040] The macromonomer (b1) is a monomer represented by Formula
(1) and is one in which a radically polymerizable group having an
unsaturated double bond is added at one terminal of the
polymethacrylic acid ester segment. In Formula (1), the notation "
. . . " indicates a state in which the monomer unit is
polymerized.
[0041] Incidentally, in the present specification, the "monomer"
means a compound having a radically polymerizable group.
[0042] Specific examples of the radically polymerizable group may
include a group having a double bond.
[0043] In Formula (1), R and R.sup.1 to R.sup.n each independently
represent a hydrogen atom, an alkyl group, a cycloalkyl group, an
aryl group or a heterocyclic group. An alkyl group, a cycloalkyl
group, an aryl group or a heterocyclic group can have a
substituent.
[0044] Examples of the alkyl group for R or R.sup.1 to R.sup.n may
include a branched or linear alkyl group having from 1 to 20 carbon
atoms. Specific examples of the alkyl group for R or R.sup.1 to
R.sup.n may include a methyl group, an ethyl group, a n-propyl
group, an iso-propyl group, a n-butyl group, an isobutyl group, a
t-butyl group, an isoamyl group, a hexyl group, an octyl group, a
lauryl group, a dodecyl group, a stearyl group, and a 2-ethylhexyl
group. Specific examples in a case in which the alkyl group for R
or R.sup.1 to R.sup.n has a substituent may include a benzyl group,
a 2-hydroxyethyl group, a 2-hydroxypropyl group, a 2-hydroxybutyl
group, a 3-hydroxybutyl group, a 4-hydroxybutyl group, a
polyethylene glycol group, a polypropylene glycol group, a
methoxyethyl group, an ethoxyethyl group, a n-butoxyethyl group, an
iso-butoxyethyl group, a t-butoxyethyl group, a phenoxyethyl group,
a nonylphenoxyethyl group, a 3-methoxybutyl group, a
methoxy-diethylene glycol group, a methoxy-tetraethylene glycol
group, a methoxy-nonaethylene glycol group, an octoxy-octaethylene
glycol-hexapropylene glycol group, and a nonylphenoxy(ethylene
glycol-polypropylene glycol) group.
[0045] Examples of the cycloalkyl group for R or R.sup.1 to R.sup.n
may include a cycloalkyl group having from 3 to 20 carbon atoms.
Specific examples of the cycloalkyl group for R or R.sup.1 to
R.sup.n may include a cyclopropyl group, a cyclobutyl group, and an
adamantyl group.
[0046] Examples of the aryl group for R or R.sup.1 to R.sup.n may
include an aryl group having from 6 to 18 carbon atoms. Specific
examples of the aryl group for R or R.sup.1 to R.sup.n may include
a phenyl group and a naphthyl group.
[0047] Examples of the heterocyclic group for R or R.sup.1 to
R.sup.n may include a heterocyclic group having from 5 to 18 carbon
atoms. Specific examples of the heterocyclic group for R or R.sup.1
to R.sup.n may include a glycidyl group, a .gamma.-lactone group
and an .epsilon.-caprolactone group. Examples of the heteroatom
contained in the heterocyclic ring may include an oxygen atom, a
nitrogen atom, and a sulfur atom.
[0048] Examples of the substituent for R or R.sup.1 to R.sup.n may
each independently include a group selected from the group
consisting of an alkyl group, an aryl group, a carboxyl group, an
alkoxycarbonyl group (--COOR'), a carbamoyl (--CONR'R'') group, a
cyano group, a hydroxyl group, an amino group, an amide group
(--C(.dbd.O)NR'R''), a halogen, an allyl group, an epoxy group, an
alkoxy group (--OR') and a group exhibiting hydrophilicity or
ionicity. Incidentally, examples of R' or R'' may each
independently include the same groups as those for R except the
heterocyclic group. Incidentally, the number of carbon atoms of the
substituent is not included in the number of carbon atoms of R or
R.sup.1 to R.sup.n.
[0049] Examples of the alkoxycarbonyl group of the substituent for
R or R.sup.1 to R.sup.n may include a methoxycarbonyl group.
[0050] Examples of the carbamoyl group of the substituent for R or
R.sup.1 to R.sup.n may include a N-methylcarbamoyl group and a
N,N-dimethylcarbamoyl group.
[0051] Examples of the amide group of the substituent for R or
R.sup.1 to R.sup.n may include a dimethylamide group.
[0052] Examples of the halogen of the substituent for R or R.sup.1
to R.sup.n may include fluorine, chlorine, bromine and iodine.
[0053] Examples of the alkoxy group of the substituent for R or
R.sup.1 to R.sup.n may include an alkoxy group having from 1 to 12
carbon atoms, and specific examples thereof may include a methoxy
group, an ethoxy group, a n-butoxy group, an iso-butoxy group, a
t-butoxy group, a phenoxy group, and a nonylphenoxy group.
[0054] Examples of the group exhibiting hydrophilicity or ionicity
of the substituent for R or R.sup.1 to R.sup.n may include an
alkali salt of a carboxyl group or an alkali salt of a sulfo group,
a poly(alkylene oxide) group such as a polyethylene oxide group or
a polypropylene oxide group, and a cationic substituent such as a
quaternary ammonium salt group. Specific examples of the
poly(alkylene oxide) group may include a polyethylene oxide group
such as a diethylene oxide group, a triethylene oxide group, a
tetraethylene oxide group, a pentaethylene oxide group, a
hexaethylene oxide group, a heptaethylene oxide group, or an
octaethylene oxide group; a polypropylene oxide group such as
dipropylene oxide group, a tripropylene oxide group, a
tetrapropylene oxide group, a pentapropylene oxide group, a
hexapropylene oxide group, a heptapropylene oxide group, an
octapropylene oxide group, or a hexapropylene oxide group; and a
combination of a polyethylene oxide group and a polypropylene oxide
group. These groups may be interposed between R.sup.1 to R.sup.n
and the oxygen atom (--O--) bonded thereto.
[0055] R is preferably a methyl group, an ethyl group, a n-propyl
group or an iso-propyl group and more preferably a methyl group
from the viewpoint of easy availability of the macromonomer (b1)
and handling properties and the balance in mechanical properties of
the polymer (B) to be obtained.
[0056] R.sup.1 to R.sup.n are preferably a methyl group, an ethyl
group, an n-propyl group or an iso-propyl group and more preferably
a methyl group.
[0057] Z is a terminal group of the macromonomer (b1). Examples of
the terminal group of the macromonomer (b1) may include a group
derived from a hydrogen atom and a radical polymerization initiator
as the terminal group of the polymer obtained by a known radical
polymerization.
[0058] n represents the number of moles of the monomer unit
(provided that, the number of the monomer unit having a double bond
is excluded) contained in one molecule of the macromonomer (b1). n
in "R.sup.n" means the same number. In other words, 1 to n of
R.sup.1 to R.sup.n (R.sup.1, R.sup.2, R.sup.3 . . . R.sup.n) are
present so as to correspond to the number of the monomer unit
(provided that, the number of the monomer unit having a double bond
is excluded) constituting the macromonomer (b1). n is an integer
from 2 to 10,000. n is preferably from 10 to 1000 and more
preferably from 30 to 500.
[0059] The macromonomer (b1) has an effect to act as a chain
transfer agent at the time of radically polymerizing a monomer
mixture containing the macromonomer (b1). Hence, it is possible to
obtain the polymer (B) having at least one kind selected from a
block copolymer or a graft copolymer without using a metal catalyst
or a sulfur compound when a monomer composition containing the
macromonomer (b1) and the other monomer (b2) to be described later
is radically polymerized, and thus the polymer (B) to be obtained
is suitable for a molded product required to have a low content of
impurities such as a metal.
[0060] In addition, it is possible to obtain a polymerized product
containing a block copolymer at relatively lower cost than the
controlled radical polymerization of the related art by the use of
the macromonomer (b1). Incidentally, examples of the controlled
radical polymerization may include a reversible
addition-fragmentation chain transfer polymerization (RAFT), atom
transfer radical polymerization (ATRP), and nitroxide mediated
polymerization (NMP). These controlled radical polymerizations are
characterized by having a controlled molecular weight and a narrow
molecular weight distribution.
[0061] In the invention, the macromonomer refers to a high
molecular compound having a polymerizable functional group and is
also called a macromer in another name.
[0062] Examples of the radically polymerizable monomer to be a raw
material for constituting the polymethacrylic acid ester segment in
the macromonomer (b1) may include, from the viewpoint of the
balance in mechanical properties of the polymer (B), methyl
methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl
methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl
methacrylate, isoamyl methacrylate, hexyl methacrylate, octyl
methacrylate, lauryl methacrylate, dodecyl methacrylate, stearyl
methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl
methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl
methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl
methacrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl
methacrylate, polyethylene glycol methacrylate, polypropylene
glycol methacrylate, PLACCEL FM (trade name, manufactured by Daicel
Corporation, caprolactone-added monomer), methoxyethyl
methacrylate, ethoxyethyl methacrylate, n-butoxyethyl methacrylate,
iso-butoxyethyl methacrylate, t-butoxyethyl methacrylate,
phenoxyethyl methacrylate, nonylphenoxyethyl methacrylate,
3-methoxybutyl methacrylate, BLEMMER PME-100 (trade name,
manufactured by NOF CORPORATION, methoxy polyethylene glycol
methacrylate (one having two chains of ethylene glycol: methoxy
diethylene glycol methacrylate)), BLEMMER PME-200 (trade name,
manufactured by NOF CORPORATION, methoxy polyethylene glycol
methacrylate (one having four chains of ethylene glycol: methoxy
tetraethylene glycol methacrylate)), BLEMMER PME-400 (trade name,
manufactured by NOF CORPORATION, methoxy polyethylene glycol
methacrylate (one having nine chains of ethylene glycol: methoxy
nonaethylene glycol methacrylate)), BLEMMER 50POEP-800B (trade
name, manufactured by NOF CORPORATION, octoxypolyethylene
glycol-polypropylene glycol-methacrylate (one having eight chains
of ethylene glycol and six chains of propylene glycol:
octoxy-octaethylene glycol-hexapropylene glycol-methacrylate)), and
BLENM ER 20ANEP-600 (trade name, manufactured by NOF CORPORATION,
nonylphenoxy(ethylene glycol-polypropylene glycol) monoacrylate).
These can be used singly or in combination of two or more kinds
thereof.
[0063] Among these, methyl methacrylate, n-butyl methacrylate,
lauryl methacrylate, dodecyl methacrylate, stearyl methacrylate,
2-ethylhexyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl
methacrylate, 4-hydroxybutyl methacrylate, methacrylic acid,
BLEMMER PME-100, BLEMMER PME-200, and BLEMMER PME-400 are preferred
from the viewpoint of easy availability of a radically
polymerizable monomer to be a raw material and the balance in
mechanical properties of the polymer (B) to be obtained. In
addition, as the radically polymerizable monomer to be a raw
material, methyl methacrylate, n-butyl methacrylate, lauryl
methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate,
2-hydroxyethyl methacrylate, BLEMMER PME-100, BLEMMER PME-200, and
BLEMMER PME-400 are more preferred and methyl methacrylate is even
more preferred from the viewpoint of favorable compatibility with
the membrane forming polymer (A), in particular PVDF.
[0064] The number average molecular weight (hereinafter, referred
to as "Mn") of the macromonomer (b1) is preferably from 1,000 to
1,000,000 from the viewpoint of the balance in mechanical
properties of the polymer (B) to be obtained. The Mn is more
preferably 3,000 or more and even more preferably 4,000 or more.
The Mn is more preferably 60,000 or less and even more preferably
50,000 or less. More specifically, the number average molecular
weight of the macromonomer (b1) is preferably from 3,000 to 60,000,
more preferably from 4,000 to 50,000, even more preferably from
5,000 to 40,000, and particularly preferably from 8,000 to
38,000.
[0065] The molecular weight distribution (hereinafter, referred to
as "Mw/Mn") of the macromonomer (b1) is preferably 1.5 or more and
5.0 or less, more preferably from 1.8 to 3.0, and particularly
preferably from 1.9 to 2.5 from the viewpoint of the balance in
mechanical properties of the polymer (B) to be obtained.
[0066] The proportion of the macromonomer (b1) unit to the entire
monomer units constituting the polymer (B) is preferably from 10 to
90% by mole and preferably from 20 to 80% by mole.
[0067] The proportion of the other monomer (b2) unit to the entire
monomer units constituting the polymer (B) is preferably from 90 to
10% by mole and preferably from 80 to 20% by mole.
[0068] The "monomer unit" means the monomer unit (monomer units)
constituting the polymer. The "entire monomer units constituting
the polymer (B)" means the sum of the number of moles of the
"macromonomer (b1) unit" and the number of moles of the "other
monomer (b2) unit".
[0069] In the invention, the macromonomer (b1) can be used singly
or in combination of two or more kinds thereof.
[0070] Examples of the production method of the macromonomer (b1)
may include a method to produce the macromonomer (b1) using a
cobalt chain transfer agent (for example, U.S. Pat. No. 4,680,352),
a method using an .alpha.-substituted unsaturated compound such as
.alpha.-bromomethylstyrene as a chain transfer agent (for example,
WO 88/04,304 A), a method to chemically bond a polymerizable group
(for example, JP 60-133,007 A, U.S. Pat. No. 5,147,952), and a
method utilizing thermal decomposition (for example, JP 11-240,854
A). Among these, a method to produce the macromonomer (b1) using a
cobalt chain transfer agent is preferred from the viewpoint of
being able to efficiently produce the macromonomer (b1).
[0071] Examples of the production method of the macromonomer (b1)
may include a bulk polymerization method, a solution polymerization
method, and an aqueous dispersion polymerization method such as a
suspension polymerization method and an emulsion polymerization
method. Among these, an aqueous dispersion polymerization method is
preferred from the viewpoint of simplification of the recovery
process of the macromonomer (b1).
[0072] Examples of the solvent (C1) used at the time of obtaining
the macromonomer (b1) by a solution polymerization method may
include a hydrocarbon such as toluene; an ether such as diethyl
ether or tetrahydrofuran; a halogenated hydrocarbon such as
dichloromethane or chloroform; a ketone such as acetone; an alcohol
such as methanol; a nitrile such as acetonitrile; a vinyl ester
such as ethyl acetate; a carbonate such as ethylene carbonate; and
supercritical carbon dioxide. These can be used singly or in
combination of two or more kinds thereof.
[0073] <Other Monomer (b2)>
[0074] The other monomer (b2) is one of the raw materials for
constituting the polymer (B) contained in the polymer composition
and the porous membrane of the invention.
[0075] Examples of the other monomer (b2) may include the same
monomer as the radically polymerizable monomer to be a raw material
for constructing the polymethacrylic acid ester segment in the
macromonomer (b1) and methyl acrylate, ethyl acrylate, n-propyl
acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate,
t-butyl acrylate, isoamyl acrylate, hexyl acrylate, octyl acrylate,
lauryl acrylate, dodecyl acrylate, stearyl acrylate, phenyl
acrylate, benzyl acrylate, glycidyl acrylate, 2-ethylhexyl
acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, 4-hydroxybutyl
acrylate, polyethylene glycol acrylate, polypropylene glycol
acrylate, PLACCEL FA (Daicel Corporation, caprolactone-added
monomer), methoxyethyl acrylate, ethoxyethyl acrylate,
n-butoxyethyl acrylate, iso-butoxyethyl acrylate, t-butoxyethyl
acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate,
3-methoxybutyl acrylate, BLEMMER AME-100 and 200 (NOF CORPORATION),
BLEMMER 50AOEP-800B (NOF CORPORATION), acrylic acid, methacrylic
acid, fumaric acid, maleic anhydride, itaconic acid, itaconic
anhydride, bicyclo[2.2.1]-5-heptene-2,3-dicarboxylic anhydride,
N-phenylmaleimide, N-cyclohexyl maleimide, N-t-butyl-maleimide,
vinyl caprate, vinyl laurate, vinyl stearate, vinyl
trifluoroacetate, butadiene, isoprene, 4-methyl-1,3-pentadiene,
1,3-pentadienestyrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, o,p-dimethylstyrene, N-methylol methacrylamide,
butoxy methacrylamide, acrylamide, N-methylolacrylamide, butoxy
acrylamide, dimethylaminoethyl (meth)acrylate, dimethylaminoethyl
(meth)acrylate methyl chloride salt, dimethylaminoethyl
(meth)acrylate benzyl chloride salt, diethylaminoethyl
(meth)acrylate, diethylaminoethyl (meth)acrylate methyl chloride
salt, diethylaminoethyl (meth)acrylate benzyl chloride salt,
3-methacryloxypropyltrimethoxysilane,
3-methacryloxypropyltriethoxysilane, and vinyltrimethoxysilane.
Among these, (meth)acrylic acid or a (meth)acrylate is preferred
from the viewpoint of being highly copolymerizable with the
macromonomer (b1). Among them, methyl methacrylate,
methoxy-diethylene glycol methacrylate, methoxy-nonaethylene glycol
methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate,
and methacrylic acid are preferred.
[0076] Here, the term "(meth)acrylic acid" means one or both of
acrylic acid having a hydrogen atom bonded to the position of a and
methacrylic acid having a methyl group bonded to the position of a.
The term "(meth)acrylate" means one or both of an acrylate having a
hydrogen atom bonded to the position of a and a methacrylate having
a methyl group bonded to the position of a.
[0077] <Monomer Composition>
[0078] In the invention, the monomer composition contains the
macromonomer (b1) and the other monomer (b2).
[0079] The content of the macromonomer (b1) with respect to 100
parts by mass of the total amount of the macromonomer (b1) and the
other monomer (b2) in the monomer composition is preferably from 5
to 99 parts by mass. The uniformity of the membrane forming
solution at the time of preparing the membrane forming solution for
obtaining the porous membrane of the invention by adding the
polymer (B) to a solution prepared by dissolving the membrane
forming polymer (A) in the solvent (C2) tends to be improved in a
case in which the content of the macromonomer (b1) is 5 parts by
mass or more, and the contact angle of pure water on the porous
membrane of the invention is 75.degree. or less in a case in which
the content of the macromonomer (b1) is 99 parts by mass or less.
The content of the macromonomer (b1) is more preferably 20 parts by
mass or more, even more preferably 40 parts by mass or more, and
particularly preferably 50 parts by mass or more. The content of
the macromonomer (b1) is more preferably 98 parts by mass or less
and even more preferably 95 parts by mass or less. More
specifically, the content of the macromonomer (b1) with respect to
100 parts by mass of the total amount of the macromonomer (b1) and
the other monomer (b2) in the monomer composition is preferably
from 40 to 98 parts by mass and even more preferably from 50 to 95
parts by mass.
[0080] As the combination of the macromonomer (b1) and the other
monomer (b2), the combination of polymethyl methacrylate
macromonomer as the macromonomer (b1) and (meth)acrylic acid or a
(meth)acrylate as the other monomer (b2) is preferred, the
combination of polymethyl methacrylate macromonomer as the
macromonomer (M), and methyl methacrylate, methoxy-diethylene
glycol methacrylate, methoxy-nonaethylene glycol methacrylate,
2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate and
methacrylic acid as the other monomer (b2) is more preferred.
[0081] <Polymer (B)>
[0082] The polymer (B) is one of the constituents of the polymer
composition and the porous membrane of the invention.
[0083] The polymer (B) is one obtained by polymerizing the monomer
composition containing the macromonomer (b1) and the other monomer
(b2) and is constituted by at least one kind selected from a block
copolymer of the macromonomer (b1) and the other monomer (b2) or a
graft copolymer of the other monomer (b2) having the macromonomer
(b1) unit at the side chain.
[0084] In the invention, the polymer (B) can contain at least one
kind selected from a polymer having only the macromonomer (b1)
unit, a polymer having only the other monomer (b2) unit, the
unreacted macromonomer (b1), or the unreacted other monomer (b2) in
addition to those described above.
[0085] The "monomer unit" means the monomer unit (monomer unit)
constituting the polymer. The "entire monomer units constituting
the polymer (B)" means the sum of the number of moles of the
"macromonomer (b1) unit" and the number of moles of the "other
monomer (b2) unit".
[0086] The Mn of the polymer (B) is preferably 1,000 or more and
5,000,000 or less from the viewpoint of the tensile strength,
tensile elongation, flexural strength and thermal stability of the
polymer (B). The Mn of the polymer (B) is more preferably 2,000 or
more and even more preferably 5,000 or more. The Mn of the polymer
(B) is more preferably 300,000 or less. More specifically, the Mn
of the polymer (B) is more preferably from 2,000 to 300,000 and
even more preferably from 5,000 to 200,000.
[0087] The polymer (B) can be used singly or in combination of two
or more kinds of polymers having different composition ratios,
chain distributions or molecular weights.
[0088] Examples of the production method of the polymer (B) may
include a bulk polymerization method, a solution polymerization
method, a suspension polymerization method, and an emulsion
polymerization method.
[0089] Examples of the solvent (C2) used in the case of producing
the polymer (B) by a solution polymerization method may include the
same solvent as the solvent (C1) used at the time of obtaining the
macromonomer (b1) by a solution polymerization method, and
tetrahydrofuran (THF), toluene (TOL), dimethylformamide (DMF),
dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO),
N-methylpyrrolidone (NMP), hexamethylphosphoric triamide (HMPA),
tetramethyl urea (TMU), triethyl phosphate (TEP) and trimethyl
phosphate (TMP). Among these, THE TOL, DMF, DMAc, DMSO and NMP are
preferred from the viewpoint of solubility of the membrane forming
polymer (A) and the polymer (B) and ease of handling. The solvent
(C2) can be used singly or in combination of two or more kinds
thereof.
[0090] At the time of producing the polymer (B), it is possible to
use a chain transfer agent such as mercaptan, hydrogen, a
.alpha.-methylstyrene dimer, or a terpenoid in order to adjust the
molecular weight of the polymer (B).
[0091] It is possible to use a radical polymerization initiator at
the time of obtaining the polymer (B).
[0092] Examples of the radical polymerization initiator may include
an organic peroxide and an azo compound.
[0093] Specific examples of the organic peroxide may include
2,4-dichlorobenzoyl peroxide, t-butyl peroxypivalate,
o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide,
octanoyl peroxide, t-butyl peroxy-2-ethylhexanoate, cyclohexanone
peroxide, benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl
peroxide, lauroyl peroxide, diisopropylbenzene hydroperoxide,
t-butyl hydroperoxide, and di-t-butyl peroxide.
[0094] Specific examples of the azo compound may include
2,2'-azobisisobutyronitrile (AlBN),
2,2'-azobis(2,4-dimethylvaleronitrile), and
2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile).
[0095] As the radical polymerization initiator, benzoyl peroxide,
AlBN, 2,2'-azobis(2,4-dimethylvaleronitrile) and
2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile) are preferred from
the viewpoint of easy availability and having a half-life
temperature suitable for the polymerization condition. These can be
used singly or in combination of two or more kinds thereof.
[0096] The amount of the radical polymerization initiator added is
preferably 0.0001 part by mass or more and 10 parts by mass or less
with respect to 100 parts by mass of the other monomer (b2).
[0097] The polymerization temperature for obtaining the polymer (B)
is preferably from -100 to 250.degree. C., for example, from the
viewpoint that the boiling point of the solvent to be used or the
use temperature range of the radical polymerization initiator is
suitable. The polymerization temperature is more preferably
0.degree. C. or higher and more preferably 200.degree. C. or
lower.
[0098] The polymer composition according to the first aspect of the
invention is preferably a polymer composition containing the
polymer (B) obtained by polymerizing a monomer composition
containing the methacrylic acid ester macromonomer (b1) that is
represented by Formula (1) in which R and R.sup.1 to R.sup.n are a
methyl group and Z is a group derived from a hydrogen atom and a
radical polymerization initiator and has a number average molecular
weight of from 3,000 to 60,000; and the other monomer (b2) that is
at least one kind selected from the group consisting of methyl
methacrylate, methoxy-diethylene glycol methacrylate,
methoxy-nonaethylene glycol methacrylate, 2-hydroxyethyl
methacrylate, 2-hydroxyethyl acrylate, and methacrylic acid.
[0099] The polymer composition according to the first aspect of the
invention is preferably a polymer composition containing the
polymer (B) obtained by polymerizing a monomer composition
containing the methacrylic acid ester macromonomer (b1) that is
represented by Formula (1) in which R and R.sup.1 to R.sup.n are a
methyl group and Z is a group derived from a hydrogen atom and a
radical polymerization initiator and has a number average molecular
weight of from 3,000 to 60,000; and the other monomer (b2) that is
at least one kind selected from the group consisting of methyl
methacrylate, methoxy-diethylene glycol methacrylate,
methoxy-nonaethylene glycol methacrylate, 2-hydroxyethyl
methacrylate, 2-hydroxyethyl acrylate, and methacrylic acid, and
polyvinylidene fluoride having a mass average molecular weight of
from 300,000 to 1,500,000 as the membrane forming polymer (A).
[0100] <Porous Membrane>
[0101] The porous membrane according to the second aspect of the
invention is formed from a resin composition containing the
membrane forming polymer (A) and the polymer (B).
[0102] The resin composition may be one obtained by further adding
the membrane forming polymer (A) to the polymer composition
according to the first aspect of the invention.
[0103] The content of the membrane forming polymer (A) in the
porous membrane according to the second aspect of the invention is
preferably from 20 to 95 parts by mass with respect to 100 parts by
mass of the total amount of the membrane forming polymer (A) and
the polymer (B). There is a tendency that a porous membrane can be
formed when the content of the membrane forming polymer (A) is 20
parts by mass or more.
[0104] In addition, there is a tendency that it is possible to have
a contact angle of pure water on the outer surface of the porous
membrane of 75.degree. or less when the content of the membrane
forming polymer (A) is 95 parts by mass or less.
[0105] The content of the membrane forming polymer (A) in the
porous membrane is more preferably 25 parts by mass or more, even
more preferably 30 parts by mass or more, and particularly
preferably 40 parts by mass or more. The content of the membrane
forming polymer (A) is more preferably 92 parts by mass or less,
more preferably 90 parts by mass or less, and particularly
preferably 85 parts by mass or less. More specifically, the content
of the membrane forming polymer (A) in the porous membrane is
preferably from 25 to 92 parts by mass, more preferably from 30 to
90 parts by mass, and even more preferably from 40 to 85 parts by
mass with respect to 100 parts by mass of the total amount of the
membrane forming polymer (A) and the polymer (B).
[0106] The content of the membrane forming polymer (A) in the resin
composition is preferably from 20 to 95 parts by mass with respect
to 100 parts by mass of the total amount of the membrane forming
polymer (A) and the polymer (B) in the resin composition. There is
a tendency that a porous membrane can be formed when the content of
the membrane forming polymer (A) is 20 parts by mass or more.
[0107] In addition, there is a tendency that it is possible to have
a contact angle of pure water on the outer surface of the porous
membrane obtained from the resin composition of 75.degree. or less
when the content of the membrane forming polymer (A) is 95 parts by
mass or less.
[0108] The content of the membrane forming polymer (A) in the resin
composition is more preferably 25 parts by mass or more, even more
preferably 30 parts by mass or more, and particularly preferably 40
parts by mass or more. The content of the membrane forming polymer
(A) is more preferably 92 parts by mass or less, more preferably 90
parts by mass or less, and particularly preferably 85 parts by mass
or less. More specifically, the content of the membrane forming
polymer (A) in the resin composition is preferably from 25 to 92
parts by mass, more preferably from 30 to 90 parts by mass, and
even more preferably from 40 to 85 parts by mass with respect to
100 parts by mass of the total amount of the membrane forming
polymer (A) and the polymer (B).
[0109] The content of the polymer (B) in the porous membrane
according to the second aspect of the invention is preferably from
1 to 50 parts by mass with respect to 100 parts by mass of the
total amount of the membrane forming polymer (A) and the polymer
(B). A porous membrane can be formed when the content of the
polymer (B) is 1 part by mass or more.
[0110] In addition, it is possible for the porous membrane to
exhibit favorable oxidative deterioration resistance and mechanical
durability when the content of the polymer (B) is 50 parts by mass
or less.
[0111] The content of the polymer (B) in the porous membrane is
more preferably 2 parts by mass or more, even more preferably 5
parts by mass or more, and particularly preferably 10 parts by mass
or more. The content of the polymer (B) is more preferably 45 parts
by mass or less, more preferably 43 parts by mass or less, and
particularly preferably 40 parts by mass or less. More
specifically, the content of the polymer (B) in the porous membrane
is preferably from 2 to 45 parts by mass, more preferably from 5 to
43 parts by mass, and even more preferably from 10 to 40 parts by
mass with respect to 100 parts by mass of the total amount of the
membrane forming polymer (A) and the polymer (B).
[0112] The content of the polymer (B) in the resin composition is
preferably from 2 to 50 parts by mass with respect to 100 parts by
mass of the total amount of the membrane forming polymer (A) and
the polymer (B) in the resin composition. A resin composition
suitable for obtaining a membrane exhibiting high water
permeability can be prepared when the content of the polymer (B) is
2 parts by mass or more.
[0113] In addition, a public resin composition to obtain a porous
membrane can be prepared when the content of the polymer (B) is 50
parts by mass or less.
[0114] The content of the polymer (B) in the resin composition is
more preferably 2 parts by mass or more, even more preferably 5
parts by mass or more, and particularly preferably 10 parts by mass
or more. The content of the polymer (B) is more preferably 45 parts
by mass or less, more preferably 43 parts by mass or less, and
particularly preferably 40 parts by mass or less. More
specifically, the content of the polymer (B) in the resin
composition is preferably from 2 to 45 parts by mass, more
preferably from 5 to 43 parts by mass, and even more preferably
from 10 to 40 parts by mass with respect to 100 parts by mass of
the total amount of the membrane forming polymer (A) and the
polymer (B).
[0115] The average pore size of the pores in the porous membrane
according to the second aspect of the invention is preferably 500
nm or less. It is suitable for obtaining a membrane which is able
to remove viruses or suspended solids in service water and exhibits
favorable fractionation performance and high water permeability
when the average pore size of the pores in the porous membrane of
the invention is 500 nm or less.
[0116] The average pore size of the pores in the porous membrane is
preferably 1 nm or more and 500 nm or less from the viewpoint of
availability of using the porous membrane for the removal of
viruses, the purification of proteins or enzymes or a service water
application. There is a tendency that the removal of viruses or
suspended solids in service water is possible when the average pore
size of the pores is 500 nm or less, and there is a tendency that a
high seepage pressure is not required at the time of treating water
when the average pore size is 1 nm or more. The average pore size
of the pores is more preferably 300 nm or less, even more
preferably 120 nm or less, and particularly preferably 95 nm or
less. More specifically, the average pore size of the pores in the
porous membrane is more preferably from 3 to 120 nm and more
preferably from 5 to 95 nm.
[0117] Incidentally, the average pore size of the pores in the
porous membrane in the second aspect of the invention refers to the
average pore size obtained by actually measuring the greatest
diameter of the pores at the outer surface portion of the porous
membrane of the invention using a scanning electron microscope
(product name: JSM-7400 manufactured by JEOL Ltd.).
[0118] Specifically, the average pore size can be determined by a
method to obtain an average pore size by selecting five or more
arbitrary locations in a range of 500 .mu.m.times.500 .mu.m for
each from the outer surface of the porous membrane, measuring the
pore size of 30 pores which are present at the five locations and
randomly selected, and determining the average value of the pore
sizes measured.
[0119] The porous membrane according to the second aspect of the
invention can have an outer surface on which the contact angle of
pure water is 75.degree. or less. The contact angle on the outer
surface of the porous membrane is an index indicating the
hydrophilicity of outer surface of the porous membrane. The outer
surface of the porous membrane exhibits higher hydrophilicity as
the contact angle on the outer surface of the porous membrane of
the invention is smaller, and thus higher water permeating
performance of the porous membrane can be expected.
[0120] It is possible for the porous membrane of the invention to
exhibit favorable water permeability as the contact angle of pure
water on the outer surface of the porous membrane is decreased to
75.degree. or less.
[0121] Examples of the method to decrease the contact angle of pure
water on the outer surface of the porous membrane may include a
method in which the porous membrane is obtained using a copolymer
of the macromonomer (b1), and a monomer having a hydrophilic
functional group such as a hydroxyl group or a carboxyl group as
the other monomer (b2) as the polymer (B). It is possible to obtain
a porous membrane in which a polymer segment having a hydrophilic
functional group is efficiently unevenly distributed on the outer
surface thereof by obtaining the porous membrane using the above
copolymer.
[0122] In addition, in a case in which the porous membrane is a
flat membrane, it is possible to decrease the contact angle of pure
water on the outer surface of the porous membrane by forming a flat
membrane by a manufacturing method including a process of coating a
polymer composition on a smooth substrate through a discharge port
(spinneret) using the polymer composition according to the first
aspect of the invention and coagulating it in a coagulating liquid.
Furthermore, it is possible to have an average pore size in a
preferred range as the above manufacturing method includes a
process of preparing an aqueous solution of the solvent (C2) as the
coagulating liquid.
[0123] In a case in which the porous membrane is a hollow fiber
membrane, it is possible to decrease the contact angle of pure
water on the outer surface of the porous membrane by forming a
hollow fiber membrane by a manufacturing method including a process
of coating a polymer composition on a hollow support in the inside
of the spinning nozzle or in the vicinity of the discharge port of
the spinning nozzle using the polymer composition according to the
first aspect of the invention and coagulating it in a coagulating
liquid. At this time, it is preferable to provide an air gap region
before coagulating the precursor of the porous membrane. The air
gap refers to the space between the discharge port and the
coagulating liquid surface to be exposed to the precursor and the
air (outside air). It is possible to cause the spinodal
decomposition of the precursor surface of the porous membrane by
the water vapor contained in the air (outside air) as an air gap is
provided, and thus more precise configuration control is
possible.
[0124] Furthermore, it is possible to have an average pore size in
a preferred range as the above manufacturing method includes a
process of preparing an aqueous solution of the solvent (C2) as the
coagulating liquid.
[0125] The contact angle of pure water on the outer surface of the
porous membrane is more preferably 73.degree. or less. In addition,
it is more preferable as the lower limit value of the contact angle
of pure water on the outer surface of the porous membrane is lower,
and the lower limit value is generally 1.degree. or more. The lower
limit value of the contact angle of pure water on the outer surface
of the porous membrane varies depending on the kind of the polymer
(A) used, and the lower limit value is generally 20.degree. or more
in the case of using PVDF as the polymer (A). More specifically,
the contact angle of pure water on the outer surface of the porous
membrane is preferably from 1 to 73.degree., more preferably from
20 to 73.degree., and even more preferably from 40 to
65.degree..
[0126] In the porous membrane according to the second aspect of the
invention, the flux of pure water is preferably
1.0.times.10.sup.-10 (m.sup.3/m.sup.2/s/Pa) or more. In a case in
which the flux is less than 1.0.times.10.sup.-10
(m.sup.3/m.sup.2/s/Pa), it is required to operate at a higher
pressure to obtain a high permeable water volume and thus it is not
cost-effective. Here, the flux is a numerical value that can be
determined by inserting the porous membrane into a stainless holder
with tank (KST-47 (trade name) manufactured by ADVANTEC Co. Ltd.),
filling deionized water in the tank, and calculating using the
following Equation.
Flux=L/(S.times.t.times.P)
Flux: flux of pure water (m.sup.3/m.sup.2/s/Pa) L: permeable volume
of pure water (m.sup.3) S: effective membrane area (m.sup.2) t:
permeation time (s) P: measuring pressure (Pa)
[0127] It is preferable that the rejecting rate of the porous
membrane of the invention with respect to the fine particles of
0.130 .mu.m or less be 90% or more.
[0128] There is a tendency that clogging in the removal of viruses,
the purification of proteins or enzymes, or the service water
application or an increase in differential pressure in filtration
occurs and the lifespan is shortened when the rejecting rate is
less than 90%.
[0129] Here, the fine particle rejecting rate is a numerical value
that can be determined by filling an evaluation stock solution
prepared by dispersing polystyrene latex particles having an
average particle size of 0.132 .mu.m (manufactured by MAX FAIR,
nominal particle size of 0.132 .mu.m) in deionized water so as to
have a concentration of 25 ppm in the tank of a stainless holder
with tank (KST-47 (trade name) manufactured by ADVANTEC Co. Ltd.),
filtering the evaluation stock solution through the porous membrane
inserted into the stainless holder with tank, and calculating from
the absorbance of the evaluation stock solution and the filtrate
measured at a wavelength of 320 nm using the following
Equation.
Rjc=[(A1-A2)/A1].times.100
Rjc: fine particle rejecting rate (%) A1: absorbance of evaluation
stock solution (abs) A2: absorbance of filtrate (abs)
[0130] The absorbance can be measured using a spectrophotometer
(LAMBDA850 manufactured by PerkinElmer Co., Ltd.).
[0131] Examples of the form of the porous membrane according to the
second aspect of the invention may include a flat membrane and a
hollow fiber membrane.
[0132] The thickness is preferably from 10 to 1,000 .mu.m in a case
in which the porous membrane is a flat membrane. There is a
tendency that the membrane exhibits high stretchability and
satisfactory durability when the thickness is 10 .mu.m or more, and
there is a tendency that the membrane can be produced at low cost
when the thickness is 1,000 .mu.m less. The thickness is more
preferably 20 .mu.m or more and even more preferably 30 .mu.m or
more in a case in which the porous membrane is a flat membrane. The
thickness is more preferably 900 .mu.m or less and even more
preferably 800 .mu.m or less. More specifically, the thickness is
more preferably from 20 to 900 .mu.m and even more preferably from
30 to 800 .mu.m in a case in which the porous membrane is a flat
membrane.
[0133] In a case in which the porous membrane according to the
second aspect of the invention is a flat membrane, examples of the
internal structure of the membrane may include a dipping structure
in which the size of the pores in the membrane cross section
(namely, cross section in the case of cutting the membrane in the
thickness direction) decreases in a particular direction or a
structure having homogeneous pores.
[0134] In a ease in which the porous membrane according to the
second aspect of the invention is a flat membrane, it is possible
to have a macrovoid or a spherulitic structure in the membrane.
[0135] The macrovoid refers to a structure having an average pore
size of the porous membrane of approximately 10 .mu.m or more.
[0136] In a case in which the shape of the porous membrane
according to the second aspect of the invention is a hollow fiber
membrane, the outer diameter of the hollow fiber membrane is
preferably from 20 to 2,000 .mu.m. There is a tendency that the
thread breakage hardly occurs at the time of forming the membrane
when the outer diameter of the porous membrane is 20 .mu.m or more.
In addition, there is a tendency that the hollow shape is easily
maintained and the membrane is hardly flattened particularly even
though an external pressure is applied when the outer diameter of
the hollow fiber membrane is 2,000 .mu.m or less. The outer
diameter of the hollow fiber membrane is more preferably 30 .mu.m
or more and even more preferably 40 .mu.m or more. In addition, the
outer diameter of the hollow fiber membrane is more preferably
1,800 .mu.m or less and even preferably 1,500 .mu.m or less. More
specifically, the outside diameter of the hollow fiber membrane is
more preferably from 30 to 1,800 .mu.m and even more preferably
from 40 to 1,500 .mu.m in a case in which the shape of the porous
membrane is a hollow fiber membrane.
[0137] In a case in which the shape of the porous membrane
according to the second aspect of the invention is a hollow fiber
membrane, the wall thickness of the hollow fiber membrane is
preferably from 5 to 500 .mu.m. There is a tendency that the thread
breakage hardly occurs at the time of forming the membrane when the
wall thickness of the hollow fiber membrane is 5 .mu.m or more. In
addition, the hollow shape tends to be easily maintained when the
wall thickness of the hollow fiber membrane is 500 .mu.m or less.
The wall thickness of the hollow fiber membrane is preferably 10
.mu.m or more and even more preferably 15 .mu.m or more. The wall
thickness of the hollow fiber membrane is more preferably 480 .mu.m
or less and even more preferably 450 .mu.m or less. More
specifically, the wall thickness of the hollow fiber membrane is
more preferably from 10 to 480 .mu.m and even more preferably from
15 to 450 .mu.m in a case in which the shape of the porous membrane
is a hollow fiber membrane.
[0138] Here, the "wall thickness of the hollow fiber membrane"
means the length from the outer surface to the inner surface of the
cross section in the case of cutting the membrane in the thickness
direction.
[0139] The porous membrane according to the second aspect of the
invention is preferably a porous membrane formed from a resin
composition containing the polymer (B) obtained by polymerizing a
monomer composition containing the methacrylic acid ester
macromonomer (b1) that is represented by Formula (1) in which R and
R.sup.1 to R.sup.n are a methyl group and Z is a group derived from
a hydrogen atom and a radical polymerization initiator and has a
number average molecular weight of from 3,000 to 60,000; and the
other monomer (b2) that is at least one kind selected from the
group consisting of methyl methacrylate, methoxy-diethylene glycol
methacrylate, methoxy-nonaethylene glycol methacrylate,
2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and
methacrylic acid, and polyvinylidene fluoride having a mass average
molecular weight of from 300,000 to 1,500,000 as the membrane
forming polymer (A).
[0140] The porous membrane according to the second aspect of the
invention is preferably a porous membrane formed from a resin
composition containing the polymer (B) obtained by polymerizing a
monomer composition containing the methacrylic acid ester
macromonomer (b1) that is represented by Formula (1) in which R and
R.sup.1 to R.sup.n are a methyl group and Z is a group derived from
a hydrogen atom and a radical polymerization initiator and has a
number average molecular weight of from 3,000 to 60,000; and the
other monomer (b2) that is at least one kind selected from the
group consisting of methyl methacrylate, methoxy-diethylene glycol
methacrylate, methoxy-nonaethylene glycol methacrylate,
2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and
methacrylic acid, and polyvinylidene fluoride having a mass average
molecular weight of from 300,000 to 1,500,000 as the membrane
forming polymer (A).
[0141] The porous membrane according to the second aspect of the
invention is a porous membrane formed from a resin composition
containing the polymer (B) obtained by polymerizing a monomer
composition containing the methacrylic acid ester macromonomer (b1)
that is represented by Formula (1) in which R and R.sup.1 to
R.sup.n are a methyl group and Z is a group derived from a hydrogen
atom and a radical polymerization initiator and has a number
average molecular weight of from 3,000 to 60,000; and the other
monomer (b2) that is at least one kind selected from the group
consisting of methyl methacrylate, methoxy-diethylene glycol
methacrylate, methoxy-nonaethylene glycol methacrylate,
2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, and
methacrylic acid, and polyvinylidene fluoride having a mass average
molecular weight of from 300,000 to 1,500,000 as the membrane
forming polymer (A), and the porous membrane is preferably a porous
membrane in which the contact angle of pure water on the outer
surface thereof is from 20 to 73.degree..
[0142] Examples of the method for producing the porous membrane
according to the second aspect of the invention may include the
following methods.
[0143] First, a membrane forming solution is obtained by dissolving
the membrane forming polymer (A) and the polymer (B) in a solvent
(C3) to be described later. Subsequently, a porous membrane
precursor is obtained by coagulating the membrane forming solution
thus obtained in a coagulating liquid. Thereafter, the solvent (C3)
remaining in the porous membrane precursor is removed by washing,
and the porous membrane precursor after washing is dried, whereby
the porous membrane of the second aspect of the invention is
obtained.
[0144] In the above method, the mixing ratio of the membrane
forming polymer (A), the polymer (B), and the solvent (C3) is not
particularly limited as long as the membrane forming solution is
uniform.
[0145] In other words, the membrane forming solution is one which
contains the resin composition and the solvent (C3).
[0146] Examples of the method of preparing the membrane forming
solution may include a method in which the membrane forming polymer
(A) and the polymer (B) are mixed at once and dissolved in the
solvent (C3) and a method in which the membrane forming polymer (A)
and the polymer (B) are dissolved in the solvent (C3) while being
added little by little.
[0147] Incidentally, at the time of obtaining the membrane forming
solution, it is possible to dissolve the membrane forming polymer
(A) and the polymer (B) while heating the solvent (C3) as long as
the temperature is equal to or lower than the boiling point of the
solvent (C3). In addition, it is possible to cool the membrane
forming solution if necessary.
[0148] Examples of the solvent (C3) may include those which are the
same as the solvent (C2). Among these, DMF, DMAc, DMSO and NMP are
preferred from the viewpoint of the solubility of the membrane
forming polymer (A) and the polymer (B) and ease of handling. The
solvent (C3) can be used singly or in combination of two or more
kinds thereof.
[0149] The content of the membrane forming polymer (A) in the
membrane forming solution is preferably from 0.1 to 40% by mass and
more preferably from 5 to 30% by mass with respect to the total
mass of the membrane forming solution. In addition, the content of
the polymer (B) in the membrane forming solution is preferably from
0.1 to 30% by mass and more preferably 1 to 15% by mass with
respect to the total mass of the membrane forming solution. In
addition, the content of the solvent (C3) in the membrane forming
solution is preferably from 50 to 99.8% by mass and more preferably
from 65 to 94% by mass with respect to the total mass of the
membrane forming solution. There is a tendency that highly uniform
membrane forming solution can be prepared as the contents of the
membrane forming polymer (A), the polymer (B), and the solvent (C3)
in the membrane forming solution are set to be in the above ranges.
The phase separation or the like is less likely to occur with the
passage of time and the time-dependent change is also small in the
case of a highly uniform membrane forming solution. Incidentally,
the membrane forming solution may be in a state in which a part of
the membrane forming polymer (A) or the polymer (B) is dispersed as
long as the membrane forming solution is uniform and able to
maintain the uniformity even though a part of the membrane forming
polymer (A) or the polymer (B) is not dissolved but dispersed.
[0150] In a case in which the porous membrane is a flat membrane,
the membrane forming solution is coated on a substrate to obtain a
coating film layered body and the coating film layered body thus
obtained is coagulated by being immersed in a coagulating liquid,
whereby the porous membrane precursor can be obtained.
[0151] The material of the substrate is not particularly limited,
but a glass substrate is preferred.
[0152] The method to coat the membrane forming solution on a
substrate is not particularly limited, but it is preferable to use
a bar coater.
[0153] The thickness of the coating film layered body can be
appropriately changed according to the desired thickness of the
porous membrane.
[0154] In a case in which the porous membrane is a hollow fiber
membrane, the membrane forming solution of the polymer composition
is coated on a hollow support and is coagulated by being immersed
in a coagulating liquid, whereby the porous membrane precursor can
be obtained.
[0155] As the coagulating liquid used at the time of obtaining the
porous membrane precursor, an aqueous solution of the solvent (C3)
used in the membrane forming solution having a concentration of
from 0 to 50% by mass is preferred from the viewpoint of pore size
control of the membrane. The amount of the coagulating liquid used
is preferably from 500 to 100,000,000 parts by mass and more
preferably from 2,000 to 50,000,000 parts by mass with respect to
100 parts by mass of the membrane forming solution.
[0156] Examples of the method to control the pore size of the
porous membrane may include a method to use an aqueous solution of
the solvent (C2) as the coagulating liquid.
[0157] The temperature of the coagulation liquid is preferably
10.degree. C. or higher and 90.degree. C. or lower. There is a
tendency that the water permeating performance of the porous
membrane of the invention can be improved when the temperature of
the coagulating liquid is 10.degree. C. or higher, and there is a
tendency that the mechanical strength of the porous membrane of the
invention is not impaired when the temperature is 90.degree. C. or
lower. The time to immerse the support coated with the membrane
forming solution in the coagulation liquid is preferably from 0.001
to 60 minutes.
[0158] It is preferable to remove the solvent (C3) by immersing and
washing the porous membrane precursor obtained in hot water at from
60 to 100.degree. C. for from 0.001 to 60 minutes. A high washing
effect for the porous membrane precursor tends to be obtained when
the temperature of the hot water is 60.degree. C. or higher, and
the porous membrane precursor tends to be hardly fused when the
temperature of the hot water is 100.degree. C. or lower.
[0159] It is preferable to dry the porous membrane precursor after
washing at 60.degree. C. or higher and 120.degree. C. or lower for
1 minute or longer and 24 hours or shorter. It is preferable for
industrial production since the time for drying treatment is short
and the production cost is also cut down when the drying
temperature of the porous membrane precursor after washing is
60.degree. C. or higher. In addition, it is preferable that the
drying temperature of the porous membrane precursor after washing
be 120.degree. C. or lower since there is a tendency that porous
membrane precursor is not too shrunk during the drying process and
also fine cracks are not generated on the outer surface of the
membrane.
EXAMPLES
[0160] Hereinafter, the invention will be described in detail with
reference to Examples. Incidentally, in the following, the
composition and structure of the macromonomer (b1) and the polymer,
the Mw of the polymer, the Mn and Mw/Mn of the macromonomer (b1)
and the polymer were evaluated by the following methods.
[0161] In addition, in the following, the "parts" and the "%"
indicate the "parts by mass" and the "% by mass", respectively.
[0162] (1) Composition and Structure of Macromonomer (b1) and
Polymer
[0163] The composition and structure of the macromonomer (b1) and
the polymer were analyzed by .sup.1H-NMR (product name: JNM-EX270
manufactured by JEOL Ltd.).
[0164] (2) Mw of Membrane Forming Polymer (A)
[0165] The Mw of the membrane forming polymer (A) was determined
using a GPC ("HLC-8020" (trade name) manufactured by TOSOH
CORPORATION) under the following conditions.
[0166] Column: TSK GUARD COLUMN a (7.8 mm.times.40 mm) and three
TSK-GEL .alpha.-M (7.8.times.300 mm) are connected in series
[0167] Eluent: DMF 20 mM LiBr solution
[0168] Measuring temperature: 40.degree. C.
[0169] Flow rate: 0.1 mL/minute
[0170] Incidentally, the Mw was determined using a calibration
curve created using the polystyrene standards manufactured by TOSOH
CORPORATION (nine kinds of Mp (peak top molecular weight) of
76,969,900, 2,110,000, 1,260,000, 775,000, 355,000, 186,000,
19,500, 1,050 and the styrene monomer (M=104) manufactured by NS
styrene Monomer Co., Ltd.).
[0171] (3) Mn and Mw/Mn of Macromonomer (b1), Controlled
Polymerization Polymer (b'1) and Polymer (B)
[0172] The Mn and Mw/Mn of the macromonomer (b1) and the controlled
polymerization polymer (b'1) were determined using a GPC
("HLC-8220" (trade name) manufactured by TOSOH CORPORATION) under
the following conditions.
[0173] Column: TSK GUARD COLUMN SUPER HZ-L (4.6.times.35 mm) and
two TSK-GEL SUPER HZM-N (6.0.times.150 mm) are connected in
series
[0174] Eluent: chloroform, DMF, or THF
[0175] Measuring temperature: 40.degree. C.
[0176] Flow rate: 0.6 mL/minute
[0177] Incidentally, the Mw and Mn were determined using a
calibration curve created using polymethyl methacrylate
manufactured by Polymer Laboratories Ltd. (four kinds of Mp (peak
top molecular weight) of 141,500, 55,600, 10,290 and 1,590).
[0178] (4) Contact Angle
[0179] The contact angle of pure water on the porous membrane was
measured by the following method.
[0180] The test piece of porous membrane was placed on a sample
table of a contact angle measuring device (product name: DSA-10
manufactured by Kruss GmbH). Subsequently, the state of the water
droplet in 3 seconds after a drop (10 .mu.l) of pure water (for
LC/MS manufactured by Wako Pure Chemical Industries, Ltd.) was
dropped on the outer surface of the sample for the contact angle
measurement was photographed using a CCD camera attached to the
device. The contact angle of the water droplet of the photograph
thus obtained was determined by an automatic measurement using the
image processing program incorporated in the contact angle
measuring device.
[0181] (5) The Average Pore Size
[0182] Five or more arbitrary locations in a range of 500
.mu.m.times.500 .mu.m were selected from the outer surface of the
porous membrane, the pore size of 30 pores which were present at
the five locations and randomly selected was measured, and the
average value of the pore sizes measured was adopted as the average
pore size.
[0183] (6) Measurement of Flux
[0184] The test piece of porous membrane was cut into a circle
having a diameter of 4.2 cm and impregnated with ethanol by being
immersed in ethanol (manufactured by Wako Pure Chemical Industries,
Ltd., special grade reagent) for 20 minutes. Subsequently, the test
piece of porous membrane impregnated with ethanol was immersed in
deionized water for two hours or longer and inserted into a
stainless holder with tank (KST-47 (trade name) manufactured by
ADVANTEC Co. Ltd., effective membrane area of 12.5 cm.sup.2). The
inside of the stainless holder with tank was filled with about 150
ml of deionized water, the top cap was then sealed with a clamp so
that there is no leakage by pressure, and the flux was calculated
from the permeable water volume per unit time measured using the
air at a measuring pressure of 0.1 MPa using the following
Equation. A greater flux value indicates higher water permeating
performance.
Flux=L/(S.times.t.times.P)
Flux: flux of pure water (m.sup.3/m.sup.2/s/Pa) L: permeable volume
of pure water (m.sup.3) S: effective membrane area (m.sup.2) t:
permeation time (s) P: measuring pressure (Pa)
[0185] (7) Fine Particle Rejecting Rate
[0186] The porous membrane used in the flux measurement was
inserted into a stainless holder with tank (KST-47 (trade name)
manufactured by ADVANTEC Co. Ltd.), an evaluation stock solution
prepared by dispersing polystyrene latex particles having an
average particle size of 0.132 .mu.m manufactured by MAGS FAIR,
nominal particle size of 0.132 .mu.m) in deionized water so as to
have a concentration of 25 ppm was filled in the tank, the
evaluation stock solution was filtered through the porous membrane
inserted at a measuring pressure of 0.1 MPa, and the fine particle
rejecting rate was calculated from the absorbance of the evaluation
stock solution and the filtrate measured at a wavelength of 320 nm
using the following Equation:
Rjc=[(A1-A2)/A1].times.100
Rjc: fine particle rejecting rate (%) A1: absorbance of evaluation
stock solution (abs) A2: absorbance of filtrate (abs).
[0187] For the absorbance measurement, a spectrophotometer
(LAMBDA850 manufactured by Perkin Elmer Co., Ltd.) was used.
(Synthesis Example 1) Synthesis of Cobalt Chain Transfer Agent
CoBF-1
[0188] Into a reactor equipped with a stirrer, 1.00 g of cobalt(II)
acetate tetrahydrate (manufactured by Wako Pure Chemical
Industries, Ltd., Wako special grade), 1.93 g of diphenyl glyoxime
(manufactured by Tokyo Chemical Industry Co., Ltd., EP grade), and
80 ml of diethyl ether (manufactured by KANTO KAGAKU, special
grade) that was deoxygenated by nitrogen bubbling in advance were
introduced under a nitrogen atmosphere and stirred for 30 minutes
at room temperature. Subsequently, 10 ml of boron trifluoride
diethyl ether complex (manufactured by Tokyo Chemical Industry Co.,
Ltd., EP grade) was added thereto, and the mixture was further
stirred for 6 hours. The mixture was filtered, and the solid was
washed with diethyl ether (manufactured by KANTO KAGAKU, special
grade) and vacuum dried for 15 hours, thereby obtaining 2.12 g of
the cobalt chain transfer agent CoBF-1 of a red-brown solid.
(Synthesis Example 2) Synthesis of Dispersant 1
[0189] Into a reactor equipped with a stirrer, a cooling tube, and
a thermometer, 61.6 parts of 17% aqueous solution of potassium
hydroxide, 19.1 parts of methyl methacrylate (trade name: ACRYESTER
M manufactured by Mitsubishi Rayon Co., Ltd.), and 19.3 parts of
deionized water were introduced. Subsequently, the liquid in the
reactor was stirred at room temperature, the exothermic peak
thereof was confirmed, and then the liquid was further stirred for
4 hours. Thereafter, the reaction mixture in the reactor was cooled
to room temperature, thereby obtaining an aqueous solution of
potassium methacrylate.
[0190] Subsequently, 900 parts of deionized water, 70 parts of a
42% aqueous solution of sodium 2-sulfoethyl methacrylate (trade
name: ACRYESTER SEM-Na manufactured by Mitsubishi Rayon Co., Ltd.),
16 parts of the above aqueous solution of potassium methacrylate,
and 7 parts of methyl methacrylate (trade name: ACRYESTER M
manufactured by Mitsubishi Rayon Co., Ltd.) were introduced into a
polymerization apparatus equipped with a stirrer, a cooling tube,
and a thermometer and stirred, the temperature thereof was raised
to 50.degree. C. while purging the inside of the polymerization
apparatus with nitrogen. Thereto, 0.053 part of
2,2'-azobis(2-methyl propionamidine) dihydrochloride (trade name:
V-50 manufactured by Wako Pure Chemical Industries, Ltd.) was added
as the polymerization initiator and the temperature thereof was
further raised to 60.degree. C. After the polymerization initiator
was introduced, 1.4 parts of methyl methacrylate (trade name:
ACRYESTER M manufactured by Mitsubishi Rayon Co., Ltd.) was added
thereto every 15 minutes five times in total in a divided manner.
Thereafter, the liquid in the polymerization apparatus was held for
six hours at 60.degree. C. while stirring, then cooled to room
temperature, thereby obtaining the dispersant 1 that was a clear
aqueous solution and contained the solid matter at 8%.
(Synthesis Example 3) Synthesis of Macromonomer (b1-1)
[0191] Into a flask with a cooling tube, 100 parts of methyl
methacrylate (trade name: ACRYESTER M manufactured by Mitsubishi
Rayon Co., Ltd.), 150 parts of deionized water, 1.39 parts of
sodium sulfate, 1.53 parts of the dispersant 1, and 0.00075 part of
CoBF-1 were introduced. The CoBF-1 was dissolved in a state in
which the liquid in the flask was warmed to 70.degree., and the
inside of the flask was purged with nitrogen by nitrogen bubbling.
Subsequently, 1 part by mass of AlBN was added thereto, and the
mixture was held for 6 hours in a state in which the internal
temperature was maintained at 70.degree. C., thereby completing the
polymerization. Thereafter, the polymerization reaction mixture was
cooled to room temperature and further filtered to recover the
polymer. The polymer thus obtained was washed with water and vacuum
dried for the night at 50.degree. C., thereby obtaining the
macromonomer (b1-1). The Mn of the macromonomer (b1-1) was 11,000,
the Mw/Mn was 2.0, and the average degree of polymerization was
(110). The introduction rate of the terminal double bond into the
macromonomer (b1-1) was almost 100%. In the case of the
macromonomer (b1-1), R in Formula (1) above was a methyl group.
(Synthesis Example 4) Synthesis of Controlled Polymerization
Polymer (b'1-1)
[0192] In to a flask with a cooling tube, 100 parts of MMA, 0.221
part of 2-cyano-2-propyl benzothionate (manufactured by
Sigma-Aldrich Co., LLC., purity of 97%>HPLC), and 100 parts of
toluene (manufactured by Wako Pure Chemical Industries, Ltd.,
special grade reagent) as the solvent (C1) were introduced, the
inside of the flask was purged with nitrogen by nitrogen bubbling.
Subsequently, 0.1 part of AIBN (manufactured by Wako Pure Chemical
Co., Wako special grade) was added thereto as the radical
polymerization initiator in a state in which the liquid in the
flask was heated and the internal temperature was maintained at
70.degree. C., and the mixture was then held for four hours, the
temperature thereof was subsequently raised to 80.degree. C., and
the mixture was held for 30 minutes, thereby completing the
polymerization. Thereafter, the polymerization reaction mixture was
cooled to room temperature and reprecipitated with a great amount
of methanol (manufactured by Wako Pure Chemical Industries, Ltd.,
special grade reagent). The polymer precipitated by the
reprecipitation was recovered and vacuum dried for the night under
the conditions of 50.degree. C. and 50 mmHg (6.67 kPa), thereby
obtaining the controlled polymerization polymer (b'1-1). The Mn of
the controlled polymerization polymer (b'1-1) was 11,000, and the
Mw/Mn was 1.1.
(Synthesis Example 5) Synthesis of Polymer (B-1)
[0193] Into a flask with a cooling tube, a monomer composition
containing 50 parts of the macromonomer (b1-1), 50 parts of PME-400
(trade name: BLEMMER PME-400 manufactured by NOF CORPORATION) as
the other monomer (b2), and 150 parts of toluene (manufactured by
Wako Pure Chemical Industries, Ltd., special grade reagent) as the
solvent (C2) was introduced, and the inside of the flask was purged
with nitrogen by nitrogen bubbling. Subsequently, 0.1 part of AlBN
(manufactured by Wako Pure Chemical Industries, Ltd., Wako special
grade) as the radical polymerization initiator was added to the
monomer composition in a state in which the monomer composition was
warmed and the internal temperature thereof was maintained at
70.degree. C., and the mixture was held for 4 hours, the
temperature thereof was subsequently raised to 80.degree. C., and
the mixture was held for 30 minutes, thereby completing the
polymerization. Thereafter, the polymerization reaction mixture was
cooled to room temperature and reprecipitated with a great amount
of hexane (manufactured by Wako Pure Chemical Co., special grade
reagent). The polymer precipitated by the reprecipitation was
recovered and vacuum dried for the night under the conditions of
50.degree. C. and 50 mmHg (6.67 kPa), thereby obtaining the polymer
(B-1).
[0194] The yield of the polymer (B-1) thus obtained was about 100%.
For the GPC measurement, chloroform was used as the eluent. The Mn
of the polymer (B-1) was 14,000, and the Mw/Mn was 2.1. The content
of the macromonomer (b1-1) unit in the polymer (B-1) determined by
.sup.1H-NMR was 50%. The evaluation results are presented in Table
1.
TABLE-US-00001 TABLE 1 Syn- Syn- Syn- Syn- Syn- Syn- Syn- Syn- Syn-
Syn- Syn- thesis thesis thesis thesis thesis thesis thesis thesis
thesis thesis thesis Exam- Exam- Exam- Exam- Exam- Exam- Exam-
Exam- Exam- Exam- Exam- ple 5 ple 6 ple 7 ple 8 ple 9 ple 10 ple 11
ple 12 ple 13 ple 14 ple 15 Polymer (B) or polymer (B') B-1 B-2 B-3
B-4 B-5 B-6 B-7 B-8 B'-1 B'-2 B'-3 Mono- Macromonomer (b1-1) 50 70
70 70 70 70 50 40 -- -- -- mer Controlled polymerization -- -- --
-- -- -- -- -- -- -- 50 compo- polymer (b'1-1) sition Another MMA
-- -- -- -- -- -- 20 30 50 70 -- (parts) monomer (b-2) PME-100 --
-- 30 -- -- -- -- -- -- -- -- PME-400 50 30 -- -- -- -- -- -- 50 30
-- HEMA -- -- -- 30 -- -- -- -- -- -- -- HEA -- -- -- -- -- 30 30
30 -- -- 50 MAA -- -- -- -- 30 -- -- -- -- -- -- Solvent (C2) TOL
150 150 150 -- -- -- -- -- 150 150 150 DMF -- -- -- 150 150 -- --
-- -- -- -- DMAc -- -- -- -- -- 150 150 150 -- -- -- Eval- Compo-
Macromonomer 50 69 70 71 67 75 75 76 -- -- -- uation sition of
(b1-1) unit results polymer Controlled -- -- -- -- -- -- -- -- --
-- 77 (B) or polymerization polymer polymer (B') (b'1-1) unit
Another MMA -- -- -- -- -- -- -- -- 50 70 -- monomer PME-100 50 31
30 -- -- -- -- -- -- -- -- (b-2) unit PME-400 -- -- -- -- -- -- --
-- 50 30 -- HEMA -- -- -- 29 -- -- -- -- -- -- -- HEA -- -- -- --
-- 25 25 24 -- -- 23 MAA -- -- -- -- 33 -- -- -- -- -- -- Molecular
weight Mn 14,000 12,000 9,000 10,000 11,000 19,000 21.000 28,000
70,000 50,000 18,800 and molecular Mw/Mn 2.1 2.5 2.5 2.3 2.4 1.9
1.9 1.9 1.4 1.3 1.3 weight distribution
[0195] The abbreviations in Table 1 indicate the following
compounds, respectively.
MMA: methyl methacrylate (trade name: ACRYESTER M manufactured by
Mitsubishi Rayon Co., Ltd.) PME-100: (BLEMMER PME-100 (trade name)
manufactured by NOF CORPORATION) PME-400: (BLEMMER PME-400 (trade
name) manufactured by NOF CORPORATION) HEMA: 2-hydroxyethyl
methacrylate (ACRYESTER HOMA manufactured by Mitsubishi Rayon Co.,
Ltd.) HEA: 2-hydroxyethyl acrylate (manufactured by Wako Pure
Chemical Industries, Ltd., Wako first grade) MAA: methacrylic acid
(trade name: methacrylic acid manufactured by Mitsubishi Rayon Co.,
Ltd.) TOL: toluene (manufactured by Wako Pure Chemical Industries,
Ltd., special grade reagent) THF: tetrahydrofuran (manufactured by
Wako Pure Chemical Industries, Ltd., special grade reagent) DMF:
N,N-dimethylformamide (manufactured by Wako Pure Chemical
Industries, Ltd., special grade reagent) DMAc:
N,N-dimethylacetamide (manufactured by Wako Pure Chemical
Industries, Ltd., Wako first grade)
(Synthesis Examples 6, 7, 13 and 14) Synthesis of Polymers (B-2),
(B-3), (B'-1), and (B'-2)
[0196] The polymers (B-2), (B-3), (B'-1), and (B'-2) were obtained
in the same manner as Synthesis Example 5 except that the monomer
compositions having the compositions presented in Table 1 were
used. The yield of the polymers (B-2), (B-3), (B'-1), and (B'-2)
thus obtained was almost 100%. For the GPC measurement, chloroform
was used as the eluent. The evaluation results of the polymers
(B-2), (B-3), (B'-1), and (B'-2) are presented in Table 1.
(Synthesis Example 8) Synthesis of Polymer (B-4)
[0197] The polymer (B-4) was obtained in the same manner as
Synthesis Example 5 except that the monomer composition having the
composition presented in Table 1 and the solvent (C2) were used and
deionized water was used instead of hexane for reprecipitation of
the polymer. The yield of the polymer (B-4) thus obtained was
almost 100%. For the GPC measurement, DMF was used as the eluent.
The evaluation results of the polymer (B-4) are presented in Table
1.
(Synthesis Example 9) Synthesis of Polymer (B-5)
[0198] The polymer (B-5) was obtained in the same manner as
Synthesis Example 7 except that the monomer composition having the
composition presented in Table 1 was used. The yield of the polymer
(B-5) thus obtained was almost 100%. For the GPC measurement,
chloroform was used as the eluent. The evaluation results of the
polymer (B-5) are presented in Table 1.
(Synthesis Examples 10, 11, and 12) Synthesis of Polymers (B-6),
(B-7), and (B-8)
[0199] The polymers (B-6), (B-7), and (B-8) were obtained in the
same manner as Synthesis Example 5 except that the monomer
compositions having the compositions presented in Table 1 and the
solvent (C2) were used and deionized water was used instead of
hexane for reprecipitation of the polymers. The yield of the
polymers (B-6), (B-7), and (B-8) thus obtained was almost 100%. For
the GPC measurement, THF was used as the eluent. The evaluation
results of the polymers (B-6), (B-7), and (B-8) are presented in
Table 1.
(Synthesis Example 15) Synthesis of Polymer (B'-3)
[0200] The polymer (B'-3) was obtained in the same manner as
Synthesis Example 4 except that the monomer composition having the
composition presented in Table 1 was used. The yield of the polymer
(B'-3) thus obtained was almost 100%. For the GPC measurement, DMF
was used as the eluent. The evaluation results of the polymer
(B'-3) are presented in Table 1.
Example 1
[0201] In a glass container, 16 parts of Kynar 761A (manufactured
by Arkema Inc., PVDF homopolymer, trade names, Mw=550,000) as the
membrane forming polymer (A), 12 parts of the polymer (B-1) as the
polymer (B), and 72 parts of NMP (manufactured by Wako Pure
Chemical Industries, Ltd., Wako special grade) as the solvent (C3)
were blended and stirred for 10 hours at 50.degree. C. using a
stirrer, thereby preparing the membrane forming solution.
[0202] The membrane forming solution thus obtained was allowed to
stand for one day at room temperature, subsequently coated on a
glass substrate using a bar coater so as to have a thickness of 125
.mu.m, thereby obtaining a coating film layered body. The coating
film layered body was immersed in a coagulating bath containing 70
parts of deionized water and 30 parts of NMP as the coagulating
bath solvent at room temperature.
[0203] The coating film layered body was allowed to stand in the
coagulating bath for 5 minutes, and the coagulated product of
coating film was then peeled off from the glass substrate and
washed with hot water at 80.degree. C. for 5 minutes to remove NMP,
thereby fabricating the porous membrane having a flat membrane
shape. The porous membrane having a flat membrane shape thus
obtained was dried for 20 hours at 70.degree. C., thereby obtaining
a test piece of porous membrane having a thickness of 95 .mu.m. The
contact angle of water on the outer surface of the test piece of
porous membrane was 60.degree., and the average pore size was 60
nm. The evaluation results are presented in Table 2.
TABLE-US-00002 TABLE 2 Exam- Exam- Exam- Exam- Exam- Exam- Exam-
Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 Membrane
Polymer Kind Kyner Kyner Kyner Kyner Kyner Kyner Kyner Kyner
forming (A) 761A 761A 301F 761A 761A 761A 761A 761A solution
Content 16 17 16 16 16 16 16 16 (parts) Polymer Kind B-1 B-1 B-1
B-1 B-1 B-2 B-3 B-4 (B) Content 12 6 12 12 12 12 12 12 (parts)
Solvent Kind NMP NMP NMP DMF DMAc NMP NMP DMF (C3) Content 72 77 72
72 72 72 72 72 (parts) Coag- Coagulating Kind NMP NMP NMP DMF DMAc
NMP NMP DMF ulating bath Content 30 30 30 30 30 30 30 30 bath
solvent (parts) Deionized Content 70 70 70 70 70 70 70 70 water
(parts) Evaluation Contact 60 61 60 60 62 63 60 45 results of angle
porous (.degree.) membrane Pore 60 68 77 55 57 90 53 32 size (nm)
Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 9 ple 10 ple 11
ple 12 ple 13 ple 13 ple 14 ple 15 Membrane Polymer Kind Kyner
Kyner Kyner Kyner Kyner Kyner Kyner Kyner forming (A) 761A 761A
761A 761A 761A 761A 761A 762A Content 16 16 17 16 17 16 17 12
(parts) Polymer Kind B-5 B-6 B-6 B-7 B-8 B-8 B-8 B-6 (B) Content 12
12 6 12 6 12 6 4 (parts) Solvent Kind DMAc DMAc DMAc DMAc DMAc DMAc
DMAc DMAc (C3) Content 72 72 77 72 77 72 77 84 (parts) Coag-
Coagulating Kind DMAc DMAc DMAc DMAc DMAc DMAc DMAc DMAc ulating
bath Content 30 30 30 30 30 30 30 0 bath solvent (parts) Deionized
Content 70 70 70 70 70 70 70 100 water (parts) Evaluation Contact
51 48 45 52 50 53 46 73 results of angle porous (.degree.) membrane
Pore 48 30 50 36 68 31 49 45 size (nm)
[0204] The abbreviations in Table 2 indicate the following
compounds, respectively.
Kynar 761A: PVDF homopolymer (manufactured by Arkema Inc., trade
name, Mw=550,000) Kynar 301F: PVDF homopolymer (manufactured by
Arkema Inc., trade name, Mw=600,000) NMP: N-methylpyrrolidone
(manufactured by Wako Pure Chemical Industries, Ltd., Wako special
grade) DMF: N,N-dimethylformamide (manufactured by Wako Pure
Chemical Industries, Ltd., special grade reagent) DMAc:
N,N-dimethylacetamide (manufactured by Wako Pure Chemical
Industries, Ltd., Wako first grade)
Examples 2 to 15
[0205] The test pieces of porous membrane were obtained in the same
manner as in Example 1 except that those presented in Table 2 were
used as the membrane forming solution and the coagulating bath. The
evaluation results thereof are presented in Table 2.
Example 16
[0206] The flux was measured using the test piece of porous
membrane obtained in Example 15, and it was 2.21.times.10.sup.-9
(m.sup.3/m.sup.2/s/Pa). In addition, the rejecting rate of the same
test piece of porous membrane with respect to polystyrene fine
particles of 0.132 .mu.m was 99.9%.
Comparative Examples 1 to 6
[0207] The test pieces of porous membrane were obtained in the same
manner as in Example 1 except that those presented in Table 3 were
used as the membrane forming solution and the coagulating bath. The
evaluation results thereof are presented in Table 3.
Comparative Example 7
[0208] The flux was measured using the test piece of porous
membrane obtained in Comparative Example 6 in the same manner as in
Example 16, and it was 1.43.times.10.sup.-9
(m.sup.3/m.sup.2/s/Pa).
[0209] In addition, the rejecting rate of the same test piece of
porous membrane with respect to polystyrene fine particles of 0.132
.mu.m was 99.0%.
TABLE-US-00003 TABLE 3 Comparative Comparative Comparative
Comparative Comparative Comparative Example 1 Example 2 Example 3
Example 4 Example 5 Example 6 Membrane Polymer (A) Kind Kyner 761A
Kyner 761A Kyner 301F Kyner 761A Kyner 761A Kyner 762A forming
Content 16 17 16 16 16 12 solution (parts) Polymer (B) Kind B'-1
B'-1 B'-1 B'-1 B'-2 B'-3 Content 12 6 12 12 12 4 (Parts) Solvent
(C3) Kind NMP NMP NMP DMF NMP DMAc Content 72 77 72 72 72 84
(parts) Coagulating Coagulating Kind NMP NMP NMP DMF NMP DMAc bath
bath Content 30 30 30 30 30 0 solvent (parts) Deionized Content 70
70 70 70 70 100 water (parts) Evaluation results of Contact 75 78
76 76 82 83 porous membrane angle (.degree.) Pore size 750 700 720
690 590 50 (nm)
[0210] The abbreviations in Table 3 indicate the following
compounds, respectively.
Kynar 761A: PVDF homopolymer (manufactured by Arkema Inc., trade
name, Mw=550,000) Kynar 301F: PVDF homopolymer (manufactured by
Arkema Inc., trade name, Mw=600,000) NMP: N-methylpyrrolidone
(manufactured by Wako Pure Chemical Industries, Ltd., Wako special
grade) DMF: N,N-dimethylformamide (manufactured by Wako Pure
Chemical Industries, Ltd., special grade reagent) DMAc:
N,N-dimethylacetamide (manufactured by Wako Pure Chemical
Industries, Ltd., Wako first grade)
[0211] In Comparative Example 1, the polymer (B'-1) using MMA
instead of the macromonomer (b1-1) was used, thus the average pore
size of the porous membrane thus obtained was 750 nm to be great,
and it was not possible to obtain a porous membrane suitable for
obtaining a membrane exhibiting favorable fractionation performance
and high water permeability.
[0212] In Comparative Example 2, the polymer (B'-1) using MMA
instead of the macromonomer (b1-1) was used, thus the average pore
size of the porous membrane thus obtained was 750 nm to be great
and the contact angle of pure water thereon was 78.degree. to be
great, and it was not possible to obtain a porous membrane suitable
for obtaining a membrane exhibiting favorable fractionation
performance and high water permeability.
[0213] In Comparative Example 3, the polymer (B'-1) using MMA
instead of the macromonomer (b1-1) was used and the kind of the
polymer (A) was changed, but the average pore size of the porous
membrane thus obtained was 700 nm to be great and the contact angle
of pure water thereon was 76.degree. to be great, and thus it was
not possible to obtain a porous membrane suitable for obtaining a
membrane exhibiting favorable fractionation performance and high
water permeability.
[0214] In Comparative Example 4, the polymer (B'-1) using MMA
instead of the macromonomer (b1-1) was used and the kind of the
solvent (C3) of the membrane forming solution and the kind of the
coagulating bath solvent were changed, but the average pore size of
the porous membrane thus obtained was 690 nm to be great and the
contact angle of pure water thereon was 76.degree. to be great, and
thus it was not possible to obtain a porous membrane suitable for
obtaining a membrane exhibiting favorable fractionation performance
and high water permeability.
[0215] In Comparative Example 5, the polymer (B'-2) using MMA
instead of the macromonomer (b1-1) was used, but the average pore
size of the porous membrane thus obtained was 590 nm to be great
and the contact angle of pure water thereon was 82.degree. to be
great, and thus it was not possible to obtain a porous membrane
suitable for obtaining a membrane exhibiting favorable
fractionation performance and high water permeability.
[0216] In Comparative Example 6, the polymer (B'-3) using the
controlled polymerization polymer (b'1-1) instead of the
macromonomer (b1-1) was used, and the average pore size of the
porous membrane thus obtained was 60 nm to be favorable but the
contact angle of pure water thereon was 83.degree. to be great, and
thus it was not possible to obtain a porous membrane suitable for
obtaining a membrane exhibiting favorable fractionation performance
and high water permeability.
[0217] In addition, in Comparative Example 7, a test piece of
porous membrane exhibiting a great contact angle of pure water of
83.degree. was used, and thus the rejecting rate of the test piece
of porous membrane with respect to polystyrene fine particles of
0.132 .mu.m was 99.0% to be high but the flux of the test piece of
porous membrane was 1.43.times.10.sup.-9 (m.sup.3/m.sup.2/s/Pa) to
be lower as compared to Example 15, and thus it was not possible to
obtain a porous membrane for obtaining a membrane exhibiting high
water permeability.
INDUSTRIAL APPLICABILITY
[0218] According to the invention, it is possible to obtain a
polymer composition and a porous membrane suitable for obtaining a
membrane exhibiting favorable fractionation performance and high
water permeability by using a polymer easily obtained by a usual
radical polymerization.
* * * * *