U.S. patent application number 14/846902 was filed with the patent office on 2015-12-31 for modification of drawn film.
The applicant listed for this patent is Rima HARING, Thomas HARING. Invention is credited to Rima HARING, Thomas HARING.
Application Number | 20150376360 14/846902 |
Document ID | / |
Family ID | 7684346 |
Filed Date | 2015-12-31 |
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United States Patent
Application |
20150376360 |
Kind Code |
A1 |
HARING; Thomas ; et
al. |
December 31, 2015 |
MODIFICATION OF DRAWN FILM
Abstract
The Invention relates to a drawn polymer film, comprising (A) a
polymer or polymer blend and at least (B) one additional component
with an average particle diameter of between 0.1 and 15 .mu.m,
which by means of (C) one or several secondary treatment steps is
processed to form a membrane after being drawn. The average
particle diameter of component (B) ranges between 0.1 and 15 .mu.m,
preferably 0.5-8.0 .mu.m, with the range between 1.0 and 7.0 .mu.m
being particularly preferred. The membranes are used for
alkene-alkane separation, electrodialysis, the desalinisation of
seawater, in fuel cell applications and other membrane
applications.
Inventors: |
HARING; Thomas; (Stuttgart,
DE) ; HARING; Rima; (Stuttgart, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HARING; Thomas
HARING; Rima |
Stuttgart
Stuttgart |
|
DE
DE |
|
|
Family ID: |
7684346 |
Appl. No.: |
14/846902 |
Filed: |
September 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13329112 |
Dec 16, 2011 |
9126147 |
|
|
14846902 |
|
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|
10477174 |
Jan 9, 2004 |
8079480 |
|
|
PCT/EP2002/005256 |
May 13, 2002 |
|
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13329112 |
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Current U.S.
Class: |
521/27 ;
264/129 |
Current CPC
Class: |
B29K 2023/12 20130101;
B01D 71/26 20130101; B29C 55/02 20130101; B29K 2105/04 20130101;
B29K 2105/256 20130101; B29L 2031/14 20130101; B01D 2325/42
20130101; Y10T 428/31504 20150401; B01D 2325/26 20130101; B01D
2323/30 20130101; Y02E 60/50 20130101; Y10T 428/25 20150115; B01D
69/141 20130101; C08J 2383/02 20130101; H01M 2008/1095 20130101;
B01D 2323/04 20130101; C08J 5/18 20130101; H01M 8/1093 20130101;
B01D 67/0088 20130101; B29C 55/005 20130101; B29L 2009/005
20130101; B29K 2995/0068 20130101; H01M 2300/0091 20130101; B29L
2031/3468 20130101; C08J 5/2206 20130101; B01D 67/0027 20130101;
C08J 5/2218 20130101; Y02P 70/50 20151101; B01D 67/0093 20130101;
B29C 37/0025 20130101; B01D 69/142 20130101; B29K 2105/16 20130101;
B01D 69/148 20130101; B01D 71/62 20130101; H01M 8/1079 20130101;
H01M 2300/0082 20130101; B29L 2007/008 20130101; C08J 5/22
20130101; C08J 2300/12 20130101; B29K 2105/0088 20130101 |
International
Class: |
C08J 5/22 20060101
C08J005/22; B01D 67/00 20060101 B01D067/00; B29C 37/00 20060101
B29C037/00; B29C 55/02 20060101 B29C055/02; B29C 55/00 20060101
B29C055/00; H01M 8/10 20060101 H01M008/10; B01D 69/14 20060101
B01D069/14 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2001 |
DE |
10122814.7 |
Claims
1. A membrane formed by a process which comprises: providing a foil
containing 20 to 98% by weight of a polymer component (A) and 80 to
2% by weight of a particle component (B), which comprises
phyllosilicates or tectosilicates distributed in the matrix of the
polymer component (A) and having a mean particle diameter of 0.1 to
15 .mu.m; stretching the foil monoaxially or biaxially to provide
cavities in the foil; filling the cavities using a process that
includes replacing the cations of the phyllosilicates or the
tectosilicates completely or partially by organic functionalizing
hydrophobization agents and post-treating with phosphoric acid to
fill the cavities in the foil.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 10/477,174, filed Jan. 9, 2004, which is a 35
U.S.C. 371 national stage application of PCT/EP2002/005256, filed
May 13, 2002, which claims priority of German Application No.
10122814.7 filed on May 11, 2001, all of which are incorporated
herein by reference.
STATE-OF-THE-ART
[0002] Already since more than 20 years stretched films are used in
technology. Polypropylene or polyethylene films formed by extrusion
are widely used in applications such as food packaging, food
container and the like. Stretched polypropylene films, particularly
biaxially stretched polypropylene films are widely used in
packaging materials for their excellent mechanical and optical
properties. They are produced generally by successive biaxial
stretching using a tenter.
[0003] Recently stretched foils with inorganic bulking agents are
used as breathable foils for diaper film. The pore diameter of
commonly employed, very economical films however is too big by
orders of magnitude, in that these foils could find use for
applications which require dense membranes, such as for use in a
fuel cell.
OBJECT OF THE PRESENT INVENTION
[0004] It is the object of the present invention to produce
economically membranes based on stretched films.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 shows a process for forming a drawn composite film
having particle components and pores or cavity formed around the
particle components, in accordance with the present invention.
[0006] FIG. 2 shows schematically intercalation of a dye molecule
into the cavities of a phyllosilicate particle.
DESCRIPTION OF THE INVENTION
[0007] The present invention concerns membranes based on stretched
films.
[0008] The above task can be resolved according to the present
invention by a stretched polymer film, comprising (A) a polymer or
polymer blend and at least (B) another component with an average
particle diameter of 0.1 to 15 .mu.m, which (C) by one or more
posttreatment steps is processed after the stretching to a
membrane.
[0009] It has now been found that you cannot process without the
stretching the foil consisting of the polymer (A) and the
particle-shaped component (B), at the same posttreatment steps (C)
to a membrane with the same properties.
[0010] The average particle diameter of the component (B) is in the
range of 0.1-15 .mu.m. Preferred is 0.5-8.0 .mu.m and particularly
preferred is the range of 1.0-7.0 .mu.m. If the diameter is smaller
than 0.1 .mu.m, a secondary agglomeration results and the resulting
particles have partly big diameters which usually lead to a tearing
of the foil in the stretching process. With regard to the form of
the particles there is no special restriction. However, spherical
particles are preferred.
[0011] Before the stretching the amount of the component (B) of the
non-stretched foil is 2 to 80% by weight, 10 to 70% by weight are
preferred and 20 to 60% by weight are preferred particularly. The
weight proportion of the polymer component (A) is correspondingly
98 to 20% by weight before the stretching, 90 to 30% by weight are
preferred and 80 to 40% by weight are preferred particularly.
[0012] There is no particular restriction as to the method by which
the particle-shaped component (B) is incorporated into the polymer
component (A). Said method includes a simple mixing method. The
mixing process can be carried out by adding the component (B) into
the melted component (A). The mixing process can take place by use
of a screw extrusion kneader (e.g. a single-screw extruder or a
twin-screw extruder), a Banbury mixer, a continuous mixer, a mixing
roll, or the like. When the component (A) can not be melted or when
it is not desired, it is dissolved in a suitable solvent or solvent
mixture. Suitable is any solvent that dissolves the component (A)
and which is at the same time not a solvent for the component (B).
Preferred solvents are water and aprotic solvents, such as
tetrahydrofurane (THF), dimethylsulfoxide (DMSO),
N-methylpyrrolidone (NMP), sulfolane and dimethylacetamide (DMAc).
The component (B) is then finely dispersed in the dissolved
component (A).
[0013] In all cases of the mixing process a composite results.
[0014] With the use of solvents these must be removed again after
drawing of a film on a suitable underlay in a drying or
precipitation process. This is state-of-the-art and for example
described in PCT/EP 00/03910 and WO 01/87992. The received foil
represents a composite foil or composit membrane. The component (B)
is dispersed in the matrix of the component (A). If the
crystallinity of the used polymer in the non-stretched film is so
great that the film in the dried state can not be stretched, then
the solvent is not completely removed. It was surprisingly noticed
that foils consisting of the components (A) and (B) which were
produced by a solvent process with a following drying process and
which are not stretchable in the dried state are very well
stretchable without destruction with a residual solvent
concentration. The stretching is carried out after this in a
temperature range which is over the melting point and below the
boiling point of the solvent remaining into the membrane. Another
solvent-free stretching process can follow this stretching
procedure.
[0015] The residual solvent concentration of the non-stretched foil
is between 2 and 30% by weight, particularly preferred is the range
between 5 and 20% by weight of solvent in the non-stretched
foil.
[0016] The stretched composite film of the present invention may be
subjected as necessary before or after the follow-up treatment (C)
to surface treatments, such as corona discharge, plasma treatment,
and the like, at one or both sides. The stretched composite film of
the present invention may be coated or laminated before or after
the post treatment (C) on one or both two sides with solvent or
solvent-free with a layer of a polymer or a polymer mixture which
carries if necessary functional groups. Indicate functional
groups.
[0017] In the case, that the component (A) can be melted
indestructibly, the stretched film containing the components (A)
and (B), not yet posttreated with the procedure (C), can be
produced by a known process without any restriction. The production
of a stretched composite film can be conducted, for example, by a
process which comprises subjecting a composition of a fusible
component (A), containing an at the same temperature not fusible
particle-shaped component (B) to melt extrusion by a T-die method
and passing the extrudate through a cooling roll, combined with an
air-knife or through nip rolls to form a film. The production of a
biaxially stretched film by successive biaxial stretching using a
tenter is preferably conducted by a process which comprises forming
a sheet or film from the above-mentioned composition by a T-die
method, an inflation method or the like, then feeding the sheet or
film into a longitudinal stretching machine to conduct longitudinal
stretching of 0.5- to 10-fold (expressed as a mechanical draw
ratio). at a heating roll temperature of 100-380.degree. C.,
preferred 120-350.degree. C. and particularly preferred
130-250.degree. C., and subjecting the monoaxially stretched film
to transversal stretching of 0.5- to 15-fold by the use of a tenter
at a tenter temperature of 100-380.degree. C., preferred
120-350.degree. C. and particularly preferred 130-250.degree. C.
The resulting biaxially stretched film is further subjected, as
necessary, to a heat treatment of 80-380.degree. C. (in this heat
treatment a transverse relaxation of 0-25% is allowed). Of course,
further stretching may be conducted after the above stretching. In
the longitudinal stretching, it is possible to combine multi-stage
stretching, rolling, drawing, etc. Monoaxial stretching alone may
be adopted to obtain a stretched film.
[0018] The particle-shaped component (B) can be organic or
inorganic. It is condition for the particle-shaped component (B)
that an opening or a void space forms around the preferably
spherical particle in the following stretching process (illus. 1).
The preferably spherical particle is after the stretching process
in a cavity or at an appropriate thickness of the film a pore has
formed around the particle-shaped component (B). If sufficient
cavities border on each other and their cross-sections overlap, a
continuous way or path from one side of the film to the other side
results, what, at long last, represents again a pore, too. The
component (B) remains after the stretching in the film.
[0019] A second path is created in the film through the stretching.
The first path or the first phase represents the polymer (A)
himself of which the film consists. The second path or phase is the
cavities which have arisen from the stretching procedure. The
particle-shaped component (B) is in the cavities. A continuous
phase from one side to the other shall be understood as a path. A
real percolation must be possible so that the way or the phase is
continuous. That is a permeating substance, a liquid (e.g. water),
a gas or ion must be able to penetrate from one side to the other
side. If the cavity is filled, then the properties of the new path
are dependent on the "filler". If the filler is ion conducting,
then the complete path is ion conducting. It is important that the
path is continuous.
[0020] All inorganic substances which form layer structures or
framework structures are particularly preferred as particle-shaped
component (B). Phyllosilicates and/or tectosilicates are
particularly preferred. All synthetic and natural zeolites are
preferred from the tectosilicates.
[0021] If the inorganic component (B) is a phyllosilicate, it is
based on montmorillonite, smectite, illite, sepiolite,
palygorskite, muscovite, allevardite, amesite, hectorite, talc,
fluorhectorite, saponite, beidellite, nontronite, stevensite,
bentonite, mica, vermiculite, fluorvermiculite, halloysite,
fluorine containing synthetical talc types or blends of two, or
more of the above-mentioned phyllosilicates. The phyllosilicate can
be delaminated or pillared. Particularly preferred is
Montmorillonite. Furthermore preferred is the protonated form of
the phyllosilicates and/or tectosilicates.
[0022] In one embodiment of the invention the component (B) which
includes layer structures and/or framework structures gets
functionalized before the stretching and/or after the stretching.
If the functionalization happens after the stretching, then it is a
part of the post treatment (C). In a preferred embodiment the
phyllosilicates and/or tectosilicates get functionalized before or
after the stretching.
[0023] Description of the Functionalized Phyllosilicate:
[0024] The term "a phyllosilicate" in general means a silicate, in
which the SiO.sub.4 tetraeders are connected in two-dimensional
infinite networks. (The empirical formula for the anion is
(Si.sub.2O.sub.5.sup.2-).sub.n). The single layers are linked to
one another by the cations positioned between them, which are
usually Na, K, Mg, Al or/and Ca in the naturally occurring
phyllosilicates.
[0025] By the term "a functionalized phyllosilicate or
tectosilicate" we understand phyllosilicates or tectosilicates in
which the layer distances are at first increased via a
intercalation of molecules by reaction with so-called
functionalization agents. The layer thickness of such silicates
before delamination of molecules carrying functional groups is
preferably 0.5 to 10 nm, more preferably 0.5 to 5 and most
preferably 0.8 to 2.
[0026] To functionalize the phyllosilicates or tectosilicates, they
are reacted (before or after production of the composites according
to the invention) with so-called functionalizing hydrophobization
agents which are often also called onium ions or onium salts. The
insertion of organic molecules often has a hydrophobization of the
silicates as a consequence, too. The expression functionalizing
hydrophobization agents is therefore used here.
[0027] The cations of the phyllosilicates or tectosilicates are
replaced by organic functionalizing hydrophobization agents in
which by the nature of the organic rest the desired chemical
functionalization can be adjusted inside and/or at the surface of
the silicate. The chemical functionalization depends on the kind of
the respective functionalizing molecule, oligomer or polymer, which
is to be incorporated into the phyllosilicate.
[0028] The exchange of the cations usually of metal ions or protons
can be complete or partial. A complete exchange of the cations,
metal ions or protons is preferred. The quantity of the
exchangeable cations, metal ions or protons is usually expressed as
milli equivalent (meq) per 1 g of phyllosilicate or tectosilicate
and is referred to as ion exchange capacity.
[0029] Preferred are phyllosilicates or tectosilicates having a
cation exchange capacity of at least 0.5, preferably 0.8 to 1.3
meq/g:
[0030] Suitable organic functionalizing hydrophobization agents are
derived from oxonium, ammonium, phosphonium and sulfonium ions,
which may carry one or more organic residues.
[0031] As suitable functionalizing hydrophobization agents those of
general formula I and/or II are mentioned:
##STR00001##
[0032] Where the substituents have the following meaning:
[0033] R1, R2, R3, R4 are independently from each other hydrogen, a
straight chain, branched, saturated or unsaturated hydrocarbon
radical with 1 to 40, preferably 1 to 20 C atoms, optionally
carrying at least one functional group or 2 of the radicals are
linked with each other, preferably to a heterocyclic residue having
5 to 10 C atoms, more preferably having one or more N atoms.
[0034] X represents phosphorous, nitrogen or carbon,
[0035] Y represents oxygen, sulfur or carbon,
[0036] n is an integer from 1 to 5, preferably 1 to 3 and
[0037] Z is an anion.
[0038] In case that Y represents carbon, one of the radicals R1, R2
or R3 is double bonded to this carbon.
[0039] Suitable functional groups are hydroxyl, nitro, phosphonic
acid or sulfonic acid groups, whereas carboxyl and sulfonic acid
groups are especially preferred. In the same way sulfonic acid
chloride and carboxylic acid chlorides are especially
preferred.
[0040] Suitable anions Z are derived from proton providing acids,
in particular mineral acids, wherein halogens such as chlorine,
bromine, fluorine, iodine, sulfate, sulfonate, phosphate,
phosphonate, phosphite and carboxylate, especially acetate are
preferred.
[0041] The phyllosilicates and/or tectosilicates used as starting
materials are generally reacted as a suspension. The preferred
suspending agent is water, optionally mixed with alcohols,
especially lower alcohols having 1 to 3 carbon atoms. If the
functionalizing hydrophobization agent is not water-soluble, then a
solvent is preferred in which said agent is soluble. In such cases,
this is especially an aprotic solvent. Further examples for
suspending agents are ketones and hydrocarbons. Usually a
suspending agent miscible with water is preferred. On addition of
the hydrophobizing agent to the phyllosilicate, ion exchange occurs
whereby the phyllosilicate usually precipitates from the solution.
The metal salt resulting as a by-product of the ion exchange is
preferably water-soluble, so that the hydrophobized phyllosilicate
can be separated as a crystalline solid, for example, by
filtration. When the functionalization takes place after the
stretching in the film, of course the phyllosilicate or
tectosilicate is available as a solid before the functionalization.
The cation exchange is made by secondary treatment of the stretched
film in a solution containing the functionalizing substances. The
removal of the cations originally bound to the silicate is carried
out either with the same solvent or with a suitable other solvent
in a second step. It is also possible to fix the cations originally
bound to the silicate as a solid, particularly as a hardly soluble
salt in and at the silicate surface. This is frequently the case
when the cation bound originally at the silicate is a two, three or
quadrivalent cation, particularly metal cation. Examples of it are
Ti4+, Zr4+, ZrO2+ and TiO2+.
[0042] The ion exchange is mostly independent from the reaction
temperature. The temperature is preferably above the
crystallization point of the medium in which the functionalizing
substances are, and below the boiling point thereof. For aqueous
systems the temperature is between 0 and 100.degree. C., preferably
between 40 and 80.degree. C.
[0043] As functionalizing substances alkylammonium ions are
preferred, in particular if as a functional group additionally a
carboxylic acid chloride or sulfonic acid chloride is present in
the same molecule. The alkylammonium ions can be obtained via usual
methylation reagents such as methyl iodide. Suitable ammonium ions
are alpha-omega-aminocarboxylic acids, especially preferred are
##STR00002##
[0044] Additional preferred ammonium ions are pyridine and
laurylammonium ions. After functionalization the layer distance of
the phyllosilicates is in general between 1 to 5 nm, preferably 1.3
to 4 nm.
[0045] The hydrophobized and functionalized phyllosilicate is freed
of water by drying. In general a thus treated phyllosilicate still
contains a residual water concentration of 0-5% by weight of water.
The functionalized phyllosilicate can then be mixed as a suspension
in a suspending agent as anhydrous as possible with the mentioned
polymers and be reprocessed to a film. In case the extrusion is
chosen to obtain the non-stretched foil, the functionalized
phyllosilicate or tectosilicate can be added to the melt. Preferred
is the addition of unmodified phyllosilicates or tectosilicates to
the melt and a functionalization of the silicates after the
stretching. This is especially preferred if the extrusion
temperature lies over the destruction temperature of the
functionalizing substances.
[0046] An especially preferred functionalization of the
tectosilicates and/or phyllosilicates is carried out with modified
dyes or their precursors, particularly with triphenyl methane dyes.
They have the
##STR00003##
general formula:
[0047] In the present invention dyes are used which are derived
from the following basic structure:
##STR00004##
[0048] The radicals R can be independently of each other hydrogen,
a group showing 1 to 40 carbon atoms, preferably a branched or non
branched alkyl, cycloalkyl- or an optionally alkylated aryl group,
these contain if necessary one or more flourine atoms. The radicals
R can correspond independently of each other to the radicals R1,
R2, R3 or R4 with the functional groups from the general formula
(I) and (II) mentioned above for functionalizing hydrophobation
agents.
[0049] To functionalize the phyllosilicate, the dye or its reduced
precursor is reacted with the silicate in an aprotic solvent (e.g.
tetrahydrofurane, DMAc, NMP). After approx. 24 hours the dye or the
precursor is intercalated into the cavities of the phyllosilicate.
The intercalation must be such, that an ion conducting group is
located on the surface of the silicate particle.
[0050] FIG. 2 shows schematically the process.
[0051] The so functionalized phyllosilicate is added as a
supplement to the polymer solution as described in application
DE10024575.7. The functionalization of the phyllosilicates or
tectosilicates can be again carried out via a cation exchange in
the stretched film. It has proved to be especially favorable to use
the preliminary stage of the dyes. The actual dyes are formed by
separation of water only in a following oxidation by an acidic
secondary treatment.
[0052] It was surprisingly noticed in the case of the triphenyl
methane dyes that a proton conductivity is supported in the
membranes produced from that. Whether it even is an anhydrous
proton conductivity cannot be said with sufficient safety. When the
dyes are not bound to the silicate so they are present in a free
form inside the stretched membrane, they bleed out already after
short
##STR00005##
time with the reaction water in the fuel cell.
[0053] According to the invention the polymer mixtures containing
sulfinate groups of the above mentioned parent application,
especially preferably the thermoplastic functionalized polymers
(ionomers) are added to the suspension of the hydrophobized
phyllosilicates. This can be done using already dissolved polymers
or the polymers are dissolved in the suspension itself. Preferably
the ratio of the phyllosilicates is between 1 and 70% by weight,
more preferably between 2 and 40% by weight and most preferably
between 5 and 15% by weight.
[0054] Another improvement compared with the parent application is
the additional addition of zirconium oxychloride (ZrOCl2) in the
membrane polymer solution and in the cavities of the
phyllosilicates and/or tectosilicates. If the secondary treatment
of the membrane is carried out in phosphoric acid, hardly soluble
zirconium phosphate is then precipitated in an immediate proximity
of the silica particle in the membrane. Zirconium phosphate
exhibits a self-proton conductivity in the operation of the fuel
cell. The proton conductivity functions by formation of hydrogen
phosphates as intermediate steps and is state-of-the-art. The
selective incorporation in a direct proximity to a water reservoir
(silicates) is new.
[0055] The stretched, micro porous film containing a
particle-shaped component (B) is subjected according to the present
invention one or more secondary treatments (C). In a special
embodiment of the invention, the micro porous foil contains
phyllosilicates and/or tectosilicates. These will be functionalized
now in one or several steps.
[0056] If the functionalized bulking agent, particularly zeolites
and representatives of the beidellite group and bentonites, is the
only ion conducting component, then its weight proportion is
generally between 5 to 80%, preferably between 20 and 70% and most
preferably in the range of 30 to 60% weight.
[0057] The polymers components of the component (A) of the
composite membranes of the present invention are defined as
follows:
(1) Main chains (backbones) of the polymer of the present
invention:
[0058] Actually all polymers are possibly as polymer main chains.
Preferred as main chains are, however: [0059] Polyolefines like
polyethylene, polypropylene, polyisobutylene, polynorbonene,
polymethylpentene, poly(1,4-isoprene), poly(3,4-isoprene),
poly(1,4-butadiene), poly(1,2-butadiene) [0060] Styrene(co)polymer
like polystyrene, poly(metylstyrene),
poly((.alpha.,.beta.,.beta.-trifluorostyrene), poly
(pentaflourostyrene) [0061] perflourinated ionomer like Nafion or
the SO.sub.2Hal-precursor of Nafion Cl, Br, I), Dow membrane,
GoreSelect membrane. [0062] N-basic polymer like
polyvinylcarbazole, polyethyleneimine, poly(2-vinylpyridine),
poly(3-vinylpyridine), poly (4-vinylpyridine) [0063] (Het) aryl
main chain polymers which contain the structural patterns listed in
illus. 1.
[0064] (Het) aryl main chain polymers are preferred particularly
as: [0065] Polyetherketones like polyetherlketone PEK Victrex,
polyetheretherketone PEEK Victrex, polyetheretherketoneketone
PEEKK, polyetherketoneetherketone ketone PEKEKK Ultrapek [0066]
Polyethersulfones like polysulfone Udel, polyphenylsulfone Radel R,
Polyetherethersulfone Radel A, polyethersulfone PES Victrex [0067]
Poly (Benz) imidazole like PBI Celazol and others the (Benz)
imidazole-group containing oligomers and polymers, in which the
(Benz) imidazole group can be available in the main chain or in the
polymer lateral chain [0068] Polyphenyleneether like e.g.
poly(2,6-dimethyloxyphenylene), poly(2,6-diphenyloxyphenylene)
[0069] Polyphenylenesulfide and copolymers [0070]
Poly(1,4-phenylene) or Poly (1,3-phenylene), which can be modified
in the lateral. group if necessary with benzoyl, naphtoyl or
o-phenyloxy-1,4-benzoyl group, m-phenyloxy-1,4-benzoyl group or
p-phenyloxy-1,4-benzoyl group. [0071] Poly(benzoxazole) and
copolymers [0072] Poly(benzthiazole) and copolymers [0073]
Poly(phtalazinone) and copolymers [0074] Polyaniline and copolymers
[0075] Polythiazole [0076] Polypyrrole (2) Polymer of the type A
(polymer with cation exchange group or the non-ionic
precursors):
[0077] The polymer type A comprises all polymers which consist of
the above-mentioned polymer main chains (1) and the following
cation exchange groups or their non-ionic precursors:
[0078] SO.sub.3H, SO.sub.3Me; PO.sub.3H.sub.2, PO.sub.3Me.sub.2;
COOH, COOMe
[0079] SO.sub.2X, POX.sub.2, COX with X=Hal, OR.sub.2,
N(R.sub.2).sub.2, anhydride radical, N-imidazol radical, N-pyrazole
radical)
[0080] Preferred as functional groups are SO.sub.3H, SO.sub.3Me;
PO.sub.3H.sub.2, PO.sub.3Me.sub.2 or SO.sub.2X, POX.sub.2. The
strongly acidic sulfonic acid groups or their non-ionic precursors
are particularly preferred as functional groups. As polymer main
chains aryl main chain polymers are preferred. Poly(etherketone)
and poly(ethersulfone) are particularly preferred.
(3) Polymers of the type B (polymers with IV-basic groups and/or
anion exchange groups):
[0081] The polymer type B comprises all polymers which consist of
the above-mentioned polymer main chains (1) and carry the following
anion exchange groups or their non-ionic precursors (with primary,
secondary, tertiary basic N):
[0082] N(R.sub.2).sub.3+Y--, P(R.sub.2).sub.3+Y, whereby the
R.sub.2 radicals can be the same or different from each other;
[0083] N(R.sub.2).sub.2 (primary, secondary or tertiary
amines);
[0084] Polymers with the N-basic (her) aryl and heterocyclic groups
shown in illus. 2.
[0085] As polymer main chains (het) aryl main chain polymers like
poly (etherketone), poly (ethersulfone) and poly (benzimidazole)
are preferably. As basic groups, primary, secondary and tertiary
amino groups, pyridine group and imidazole group are preferred.
(4) Polymers of the type C polymers with cross-linking groups like
sulfinate group and/or unsaturated groups):
[0086] The polymertyp C comprises all polymers which consist of the
above-mentioned polymer main chains (1) and cross-linking groups.
Cross-linking groups are, for example:
[0087] 4 a) Alkene groups: Polymer C(R.sub.13)=C(R.sub.14R.sub.15)
with R.sub.13, R.sub.14, R.sub.15=R.sub.2 or R.sub.4
[0088] 4 b) Polymer Si (R.sub.16R.sub.17) H with R.sub.16,
R.sub.17=R.sub.2 or R.sub.4
[0089] 4 c) Polymer-COX, polymer-SO.sub.2X, polymer-POX.sub.2
[0090] 4 d) Sulfinate group polymer-SO.sub.2Me
[0091] 4 e) Polymer N (R.sub.2).sub.2 with R.sub.2.noteq.H.
[0092] One of the mentioned cross-linking groups or several of the
mentioned cross-linking groups can lie on the polymer main chain.
The cross-linking can be carried out by the following literature
known reactions: [0093] (I) Group of 4 a) by addition of peroxides;
[0094] (II) Group of 4 a) with group of 4 b) under Pt catalysis via
hydrosilation; [0095] (III) Group 4d) with dihalogenalkane or
dihalogenaryl crosslinkers (for e.g. Hal-(CH.sub.2).sub.x-Hal,
x=3-20) with S-alkylation of the sulfinate group; [0096] (IV) Group
4e) with dihalogenalkane or dihalogenrryl crosslinkers (for e.g.
Hal-(CH.sub.2)--Hal, x=3-20) with alkylation of the tertiary basic
N-group [0097] (V) Group 4d) and group 4e) with dihalogenalkane or
dihalogenaryl crosslinkers (for e.g. Hal-(CH.sub.2).sub.x--Hal,
x=3-20) with S-alkylation of the sulfinate group and alkylation of
the tertiary basic N-- [0098] (VI) Group of 4 c) by reaction with
diamines.
[0099] The cross-linking reactions (III) and (IV) and (V) are
preferred, particularly the cross-linking reaction (III).
(5) Polymers of the type D (polymers with cation exchange groups
and anion exchange groups and/or basic N groups and/or
cross-linking groups):
[0100] The polymertyp D comprises polymers which contain the
above-mentioned polymer main chains (1) and which can carry
miscellaneous groups: the cation exchange group listed in (2) or
their non-ionic precursor and the anion exchange group listed in
(3) or primary, secondary or tertiary N-basic groups and/or the
cross-linking groups listed in (4).
[0101] The following combinations are possible:
Polymer D1: Polymer with cation exchange groups or their non-ionic
precursors and with anion exchange groups and/or N-basic groups
Polymer D2: Polymer with cation exchange groups or their non-ionic
precursors and with cross-linking groups Polymer D3: Polymer with
anion exchange groups and/or N-basic groups and with cross-linking
groups Polymer D4: Polymer with cation exchange group or their
non-ionic precursors and with anion exchange groups and/or N-basic
groups and with cross-linking groups
[0102] In the following will be described how stretched films
containing an inorganic particle-shaped component (B) will be
posttreated such that membranes are available for fuel cell
applications, alkene alkane separation, electrodialysis, reverse
osmosis, dialysis, pervaporation, electrolysis and other membrane
applications.
[0103] A fusible stretchable polymer e.g. polypropylene is
compounded with an inorganic particle-shaped component (B),
preferably a component containing layer structures and/or framework
structures, particularly a phyllosilicate and/or tectosilicate with
an average particle size of 5-10.mu.. By compounding is understood:
The polymer is intimately mixed in a melt state with the inorganic
component, here, the silicate. A common method is mixing the
components in the twin-screw extruder. As a result one obtains a
composite, here silicate into polypropylene. The bentonite
montmorillonite is used exemplarily as a silica containing
component subsequently. However, this does not mean any special
restriction on bentonites.
[0104] The film is stretched now according to known methods as
described further above.
[0105] The stretched foil represents now a micro porous membrane.
The pore size is dependent on the grain size, elongation properties
of the polymer and of the tractive forces which were used during
the stretching. As a dense membrane it is completely useless.
Gasses e.g. penetrate roughly unhindered through.
[0106] For the membranes of the present invention organically
modified clay or zeolite is used. Bentonites are clays and
montmorillonite is a special bentonite. Montmorillonite is
preferred. However, all other substrates into which low molecular
compounds can intercalate can also be used. Montmorillonite is able
to tie molecules to itself by intercalation. Montmorillonite is
modified such that a strongly basic component juts out of the
particle or is on the particle surface. This organic modification
is prior art. The organic component is preferably containing
nitrogen. Heterocycles are particularly preferred and among those
imidazoles and guanidine derivatives. This shall not mean any
restriction to these two substance classes. Every other substance
class which contains a strong endstanding base is also
possible.
[0107] This organically modified montmorillonite is compounded with
the polymer, extrudated to a foil and after that stretched. In the
case of polypropylene, up to 70% by weight can be easily
incorporated. Particularly preferred are 50-60% by weight. As a
result a micro porous stretched film with clay particle is obtained
which carries imidazole groups on its surface. This film is now
posttreated with phosphoric acid. The phosphoric acid penetrates
into the film and forms a compound with the imidazole groups.
Furthermore still existing cavities both in the inorganic particle
and outside are filled with phosphoric acid. The film has become
now a dense proton-conducting membrane and is already usable in
this condition in a fuel cell such as.
[0108] To seal up further the membrane against the "bleeding" of
the phosphoric acid, the membrane is dipped into zirconium
oxychloride solution according to the present invention. An
insoluble zirconium phosphate is precipitated at the phase boundary
to the membrane and in the membrane itself. The membrane is further
sealed up by this process. Zirconium phosphates support proton
conductivity. This membrane is suitable for use in the fuel
cell.
[0109] When using thermoplastics as a polymer component, such as
polysulfone or Vectra 950 (of Ticona), the membrane formed from it
is applicable for the PEM fuel cell. Also for temperatures above
80.degree. C.
[0110] It is the advantage of the procedure of the present
invention that the film is extruded and is not drawn out of a
solvent.
[0111] The above-mentioned procedure with a polymer stretched to a
film, organically modified clay, imidazole, phosphoric acid and
after that partial precipitation to zirconium phosphate is only an
exemplary special example of the fundamental invention.
[0112] A second path is created in the film through the stretching.
The polymer component (A) of which the film consists represents the
first path itself. The cavities or the pores which have arisen from
the stretching procedure are the second path. As a path a
continuous way from one side to the other shall be understood. A
real percolation must be possible so that the way is continuous.
That is water vapor e.g. must be able to penetrate from one side to
the other side. If the cavity is filled, then the properties of the
new path are dependent on the "filler". If the filler is ion
conducting, then the complete path is ion conducting. It is
important that the path is continuous. The film before the
stretching can be produced by extrusion. However, it is also
possible to produce the film out of a solvent.
[0113] The production of the film with the modified or unmodified
bulking agent out of a solvent is prior art.
[0114] The extrusion presupposes a melting of the polymer. Most of
the functionalized polymers can not be extruded without
considerable disadvantages. If the polymer contains sulfonic acid
groups or chemical precursors like sulfochlorides, it degenerates
before it melts. In such cases the production is preferred through
a solvent containing process.
[0115] The properties of the two paths can be modified over an
almost arbitrary range. It is a problem in fuel cell engineering
that proton conductivity works below 80.degree. C. with hydrated
membranes works particularly well (e.g. Nafion). Above this
temperature water is lost increasingly and the proton conductivity
and with that the performance drops as a consequence. According to
prior art it has been attempted to solve this problem by producing
composite materials from a polymer and an inorganic bulking agent
which is also proton conducting or supports proton conductivity.
The problem is that the individual paths, that is inorganic bulking
agent or organic ionomer are not independently of each other
continuous from one side of the membrane to the other side of the
membrane.
[0116] Stepping up from prior art and according to the present
invention a membrane is produced. It contains a water-dependent
polymeric proton-conductor, e.g. a polymeric sulfonic acid and an
inorganic component which, if necessary, has been organically
modified before. This film is now stretched and the resulting
second path is filled with an at higher temperature T>80.degree.
C.) proton conducting substance. The filling can be obtained e.g.
by alternating post-treatment of the microporous membrane in
phosphoric acid and zirconium oxychloride (ZrOCl2). This process
can be repeated so often until no further zirconium phosphate
precipitates in the membrane. However, the precipitation of
zirconium phosphate is only one possibility. E.g. a sulfonated
polyetherketone or polysulfone is used as polymer.
[0117] As a result one gets a membrane which has two continuous
proton conducting paths. Below 80.degree. C. the proton
conductivity works predominantly through polymer sulfonic acid
swollen in water and in the temperature range above through the
inorganic proton conductor. A fluent transition takes place.
[0118] In another embodiment the concept of the two paths is
reduced to an unfinished microporous membrane which is adapted in a
second modification step to the desired application. There are two
membranes which are joined together to one without that they
disturb themselves in their membrane function. Another clear
picture is a textile substance woven from two threads with
different color. Whereby the threads can be chosen in a very broad
range. However, one of the threads is inserted in the finished
homogeneous fabric afterwards.
[0119] The procedure is exemplarily once again schematically
described in the particular preferably case, that the component (A)
is a without degradation fusible polymer and that the
particle-shaped component (B) is a phyllosilicate or tectosilicate
with an average size of 0.1 to 15.mu..
[0120] A microporous film is obtained by extrusion of a composite,
which contains the components (A) and (B), and subsequent
stretching. This microporous foil is posttreated in a solution with
molecules which have at least two functional groups in the same
molecule. One of the functional groups in the molecule has a
positive charge, preferably this is a positively charged nitrogen
atom. The positively charged nitrogen intercalates in the layer
structures or framework structures of the silicate. A cation
exchange takes place. A nitrogen cation also results from
protonation of a primary, secondary or tertiary nitrogen e.g. by
the acidic silicate which intercalates into the silicate. The
cation exchange at the silicate can, as mentioned already further
above, take place completely or partly. The resulting membrane is
for certain membrane applications as alkene alkane separation
already sufficiently sealed up. The remaining functional group not
intercalated in the phyllosilicate or tectosilicate can be a
precursor of an ion conducting group. For example sulfonic acid
chlorides, carbonic acid chloride or phosphonic acid chlorides.
Further examples of precursors of cations or anion exchange groups
are given above. These precursors are converted in further
posttreatment in a group supporting the selective permeation. E.g.
this is a hydrolysis in the case of the sulfonic acid halides which
takes place in the acidic, neutral or alkaline medium. To seal the
film up further, the stretched film is now alternatingly spiked
with a multivalent metal salt, e.g. Ti.sup.4+, Zr.sup.4+,
Ti.sup.3+, Zr.sup.3+, TiO.sup.2+, ZrO.sup.2+, and an acid, which
can be low or high molecular. As acids phosphoric acid and
sulphuric acid diluted with water are particularly preferred.
[0121] The phosphoric acid has a concentration of 1-85% by weight.
Preferred is a concentration from 20 to 80% by weight. The
sulphuric acid has a concentration from 1 to 80% by weight. A
concentration from 20 to 50% by weight is preferred. The process of
precipitation of a hardly soluble proton conductor in the membrane
can be repeated severalfold.
[0122] Any substance can be used as an inorganic component which on
stretching has the consequence that free cavities form around this
substance (see illus. 1: Process of the cavity formation by
stretching). It is not mandatorily necessary either that the
component must be inorganic. The only condition, as said already,
is that void space has formed around the particle after the
stretching. The stretching can be carried out monoaxially or also
biaxially. A biaxial stretching is preferred. For the application
in hollow fibers, however, a monoaxial stretching is
sufficient.
[0123] Additionally stretching is possible also over the third
direction in space, that is triaxially. For this purpose e.g. the
composite extruded to the film is hold level above vacuum nozzles
and a plate which also can draw a vacuum through small pores
touches down from above. The film is now fixed between two plates.
If one pulls the two plates out of each other under applied vacuum
and chooses the distance such, that the film does not break but
stretches only, a film is obtained that was stretched in
thickness.
[0124] Further application finds the invention in
electrodialysis.
[0125] The microporous stretched membrane consists of a cation
exchanger and the second path consists of an anion exchanger, if
necessary with proton leaching, e.g. as described in DE 19836514 A1
(Illus. 3; Drawings page 2). Is this membrane is placed in an
electrical field, the water in it dissociates into protons and
hydroxyl ions. The protons move along the cation exchange path to
the cathode and the hydroxyl ions (OH--) move along the anion
exchange path to the anode in accordance with the electrical field.
This way membranes can be established very economically and simply
for electrodialysis.
[0126] However, the paths also can be exchanged. An anion exchange
membrane or a chemical precursor of the anion exchange group is
then stretched first and the second path is now a cation exchange
membrane. The modification of the inorganic component must be
chosen correspondingly.
[0127] An advantage of the invention has been mentioned only
briefly before. Ionomers can not be extruded as a rule. So Nafion
cannot be extruded without plasticisers. The plasticiser (aid to
the extrusion) is later very difficult to remove from the membrane.
However, this is necessary for the operativeness of the
membrane.
[0128] Organically modified particles (e.g. montmorillonite) can be
processed according to the present invention in fusible and
therefore extrudable polymers to films. In the second step the
continuous path is formed by the stretching and then filled with
the ion conductor.
[0129] By particle-shaped inorganic layer structures or framework
structures containing the component (B) an otherwise under the
application conditions of a membrane mobile or volatile functional
groups carrying chemical substance of the general formula for
hydrophobization functionalization agents (I) or (II) is fixed in
the microporous film over a technically applicable time period so
that it can be used for membrane applications.
[0130] This allows an enormous reduction in the production costs.
Large areas of a "rawly" membrane can be produced in large existing
plants, which are modified depending on the application in a second
step. So membranes are very economically producible according to
this procedure for the desalination of sea water. E.g.
polypropylene is used as a basic polymer here. The inorganic
component, e.g. montmorillonite, is modified organically before
such that a charged group remains at the surface. E.g. this can be
done with an alpha-omega amino sulfonic acid. After the stretching
a loaded micro porous membrane results. This is suitable for
reverse osmosis.
[0131] Furthermore cross-linking reactions can still be carried out
within the pores through endstanding groups of the
functionalization agents capable of crosslinking. This can be a
covalent and/or an ionic cross-link.
[0132] Another application is the use in the alkene alkane
separation.
[0133] Nitrogen in heterocycles with a free electron pair forms
with silver ions, e.g. silver nitrate solution, a hardly soluble
complex. It has now been found surprisingly that if this complex is
located in a membrane, it is capable to bind alkenes
reversibly.
[0134] A film is made from polybenzimidazole and soaked in a
diluted to concentrated silver salt solution, preferred is silver
nitrate, over a period of 24 hours up to two weeks, then this
membrane has a separation efficiency on alkene alkane mixtures. As
a solvent for the silver salt water or an aprotic solvent can be
used. Alkenes and olefines permeate through such a membrane
anhydrously with a technically applicable flow rate. An improvement
in the flow number is reached by insertion of organically modified
montmorillonite with heterocyclical nitrogen on the surface,
bearing at least a free electron pair, e.g. an endstanding
imidazole group. The membrane is stretched carefully and soaked
after this in silver salt solution. By the stretching channel
structures which make the transport easier are produced in the
membrane.
[0135] A considerable cost reduction is obtained if a unmodified
polymer, e.g. polypropylene is stretched with organically modified
montmorillonite. The montmorillonite carries again endstanding
imidazole or pyridine groups on its surface. After the stretching
the microporous membrane is soaked in a silver ion containing
solution. After this the membrane is suitable for the alkene alkane
separation. The membrane is suitably for the separation of low
molecular substances, of which one component of the mixture
contains a double bond, which forms a reversible complex with
silver ions. The separation of low molecular olefine/alkane
mixtures is particularly preferred.
[0136] The montmorillonite does not have to be modified
compulsorily. Polypropylene is compounded with montmorillonite and
stretched. After this the porous film is posttreated with a
solution containing aromatic nitrogen bearing at least one free
electron pair. The solvent can be any suitable solvent or solvent
mixture. Water and aprotic solvents are preferred. It is only
important that the corresponding molecule containing nitrogen
penetrates into the cavities of the clay and fills out the pores.
In the following step the membrane is posttreated in a silver or
copper ion containing solution. Any solvent is suitably that holds
silver ions or copper ions in solution. Particularly preferred is
water and aprotic solvents such as DMSO, NMP and THF. As a
consequence the nitrogen silver ion complex or the nitrogen copper
ion complex precipitates in the membrane. This process can if
necessary be repeated severalfold. The membrane is now suitable for
the anhydrous alkene alkane separation.
* * * * *