Note: Descriptions are shown in the official language in which they were submitted.
17~
1 BACKGROUND OF THE INVENTION
1. Field of the Invention
.
This invention relates to a graft copolymer comprising
a hydrocarbon polymer as a main chain to which a side chain
composed of a styrene compound of the formula (I)
~ '`
(I)
1 0 (OR) n
wherein R is a hydrogen atom or an R'CO group in which R' is
an alkyl group, and n is an integer of 1 or 2, and a polyene
compound is grafted; and to a process for preparing the graft
copolymer.
?. Description of the Prior Art
It is well known that hydroaarbon polymers having styrene
compounds of the formula ~I) grafted thereto have a wide range
of utility, but it is desired to improve their adhesiveness,
O dyeability, reactivity with other compounds, mechanical and
chemical properties further.
On the other hand, it has previously been known to use
polyhydroxystyrene as an ion-exchange membrane. However,
membranes of ~olyhydroxystyrene have the defect of inferior
mechanical strengthO With a view to increasing the mechanical -~
s~trength of polyhydroxystyrene ion-exchange membranes, Japanese
Patent Publication No. 26955/72 discloses a method for producing
cationic exchange membranes from poly(E-hydroxystyrene~ in which ~;
an inert polymer such as polyvinyl chloride is used conjointly,
and poly~ hydroxystyrene) is us;ed in a partially chlorinated
state.~ The partial chlorination of poly(~hydroxystyrene) is no~
$~ : ~
.
~ ;....... ..... ;
76~3~
.
1 desirable because partial chlorination complicates the process
of producing ion-exchange membranes, and results in an increased
cost of production and in a decreased number of reactive sites
into which various functional groups can be introduced which is
a characteristic of polyhydroxystyrene.
S~MMARY OF THE INVENTION
: .
An object of this invention is to provide a novel graft
copolymer having superior characteristics.
Another object of this invention is to improve the
':
adhesiveness, dyeability, resistance to oxidation, reactivity
with other compounds, and mechanical characteristics of hydro-
carbon polymers.
Still another object of this invention is to provide a
process for preparing the above novel graft copolymer.
A fùrther object of this invention is to provide a
graft copolymer which can be used as ion-exchange membranes of
excellent quality, or as a basic polymer matrix of ion-exchange
membranes.
An even further object of this invention is to provide a -
; graft copolymer which can become a basic polymer matrix of ion-
; exchange membranes, which has sufficient reactive sites into
which ion-exchange groups can be introduced, and which permits
introduction of ion-exchange groups under mild conditions.
A still further object of this lnvention is to provide
an ion-e~change membrane having good electrical properties,
superior mechanical strength, stability to various chemical
treatments, and durability, or a basic polymer matrix from ~-~
which such ion-exchange membranes can be produced.
The graft copolymer of this invention comprises a main
chain of a hydrocarbon pol~mer and a side chain composed mainly
- 2 - -
' '
.': :
7~;8~
1 of a styrene compound of the following formula ~I)
CH=CH2 :
tI)
'
wherein R is a hydrogen atom or an RICO group in which R' is
an alkyl group, an n is an integer of l or 2, and a polyene
compound having at least two polymerizable double bonds in the
molecule grafted to the main chain. ..
DETAILED DESCRIPTION OP THE INVENTION
The graft copolymer of the invention can be prepared by
graft copolymerizing a monomeric mixture:composed mainly of the ~-
styrene compound of formula (I) and the polyene compound with a .
hydrocarbon polymer using ionizing radiation; or by first
grafting the styrene compound of formula (I) to the hydrocarbon .
.
polymer: using ionizing radiation, and then introducing the ~ ~
polyene compound lnto the resulting graft copolymer uslng ~ . .
;~ ~ ionizing radiatlon. ~ .
~ The hydrocarbon-polymers used in:this i:nvention can be
:aliphatic:~hydrocarbon polymers, especially those hydrooarbon ..
polymers of monomer~un1ts c~ontaining 2~to l0 carbon atoms, such . .;~
as polyethylene, polypropylene~or polybutene:; aromatic hydro~
: ~:carbon polymers, especially polymers of monomer units represented
: by the~general formula ~
wherein~R~l., R2:and~R3 each represents~a hydrogen atom or an
alkyl group having~l~to~lQ carbon~atoms, and A is an aryl group, ~::~. ..
or~R' ~ 6 in whLch R4, Rs~ R6~ R'4~ ~'7 and R'6 `~
:" ~
1 each represents a hydrogen atom or an alkyl group having 1 to
10 carbonatoms, such as polystyrene, poly(~-methylstyrene) or
poly(tertiary butylstyrene); alicyclic hydrocarbon polymers,
especially polymers of monomer units represented by the general
formula ~III)
R7CH = CHR8 (III)
in which R7 and R8 each represents a hydrogen atom or an alkyl
group having 1 to 10 carbon atoms, and at least one of R7 and R8
is a cycloalkyl group, such as polyvinyl cyclohexane; or co-
polymers derived from two or more of the above described monomer
units. The hydrocarbons that make up the main chain of the
graft copolymer can contain branched chains.
The range of the degree of polymerization of these
polymers is such that the polymers are solid at noxmal tem- -
peratures (e.g., 20-30C). The polymers can be used in various
forms, as desired, such as powders, granules, fibers or films.
The styrene compounds used in the graft copolymerization
; in accordance with this invention are hydroxystyrene compounds
and acyloxystyrene compounds as shown below. The hydroxy or
acyloxy substituents can be at any available positions, and
the styrene compound can be an isomeric mixture of styrene
compounds.
CH=CH2 CH=CH2 CH=CH2 CH=CH2
~ OH OCOR' ~O OH R'COO OCO~'
.. ... . .
Hydroxystyrene can be o-, m- or p- hydroxystyrene but, generally,
p-hydroxystyrene is preferably used. ~Also, dihydroxystyrene can
be 1,2-, 1,3- or 3,4-dihydroxystyrene but, generally, 3,4-di-
~; 30 hydroxystyrene is preferably used. In the acyloxystyrenes, R' i5
',,' , :
: ' .
., ' ' ~ .
, . ` :: : . . .
.L~47~
1 a hydrocarbon group containing 1 to 20 carbon atoms, such asa straight chain or branched chain alkyl group, or a -~CH2)n-P
group in which P is a cycloalkyl group, an alkyl-substituted
cycloalkyl group, an aryl group or a Rg- ~ Rll group in which
Rg, Rlo and Rll each represents a hydrogenatom or an alkyl
group having 1 to 10 carbon atoms, and n is 0 or an integer such
that the total number of carbon atoms in the ~ CH2 ~ P group is
not more than about 20. Suitable examples of acyloxystyrenes are
monoacetoxystyrene or 1,2~, 1 r 3- or 3,4-diacetoxystyrene, mono-
10 propionyloxystyrene or 1 r 2- r 1,3- or 3 r 4-dipropionyloxystyrene r
monobutyryloxystyrene or 1,2- r 1,3- or 3,4-dibutyryloxystyrene,
benzoyloxystyrene and the like r preferably p-acetoxystyrene or
3 r 4-diacetoxystyrene.
The polyene compound used in the graft copolymerization ~ -
~..
in accordance with this invention is a polyene compound con-
taining at least two polymerizable double bonds in the molecule.
Examples of suitable polyene compounds that can be used in this -
invention are aliphatic compoundsr alicyclic compounds containing ~
:: .::
double bonds in the ring or substituents, and aromatic compounds ;
20 having unsaturated substituents. Examples of suitable aliphatic
compounds are aliphatic hydrocarbons r and aliphatic esters r for
.
example r diesters formed between unsaturated acids and diols r . '~
diesters formed between diacids and unsaturated alcohols, esters
- ~,
formed between unsaturated acids and unsaturated alcohols r
::
diesters formed between unsaturated acids and unsaturated diols
: : :
and diesters formed between unsaturated dicarboxylic acids and -
unsaturated alcohols. Generally, these compounds have 4 to 20
carbon atoms. Specific examples of the polyene compounds are
divinylben~enes r isoprene, butadiene r cyc1opentadiene r ethy~lidene
norborene r diol esters of acrylic acid or methacrylic acid, or
. ~ :
~: .. .
~0~76~
1 divinyl esters of adipic acid. Of these compounds, divinyl-
benzenes and isoprene are especially preferred. The o-, m- and
p-isomers of divinylbenzene and mixtures thereof can all be used
in this invention. Generally, a mixture of these isomers is used.
Generally, commercially available divinylbenzene sometimes
contains about 45% by weight of ethylvinylbenzene, and this
mixture can be used as such in the present invention as well.
The monomer to be graft copolymerized in this invention
can be a mixture of an acyloxystyrene and a polyene compound, a
10 mixture of hydroxystyrene and a polyene compound, or a mixture
of an acyloxystyrene, hydroxystyrene and a polyene compound.
Instead of using a solution containing both the styrene
compound monomer and the polyene compound monomer, the graft
copolymerization can first be carried out using a solution con-
taining only the styrene compound monomer to form a graft ;
copolymer in which a side chain composed of the styrene compound
is grafted to a main chain of a hydrocarbon polymer, and then -~
the polyene compound can be introduced into the graft copolymer
:: .
using ionizing radiation, which also has the effect of induciny
20~ crosslinking of the copolymer by the polyene compound.
The mixing ratio between the styrene compound and the
polyene compound can be selected as desired. Since the properties
of the graft copolymer obtained vary according to the mixing
ratio, the mixing ratio should be selected according to the
properties desired in the graft copolymer. General~y, as the
proportion of the polyene compound increases, the mechanlcal
properties of the graft copolymer, especially its~strength as
a membrane, are improved, and its electric resistance also
:
increases. However, if the proportion of the polyene compound
30 becomes too high, the degree oi crosslinking becomes too high,
; - 6
t:
.
-
~IL[)~L76~
1 making it difficult to perform the grafting reaction. Further-
more, the resulting product becomes brittle, and since the amount
of the styrene compound to be grafted decreases, the properties
of the polymer, such as its adhesiveness, dyeability or oxidation
resistance, tend to be deteriorated. Accordingly, the weight
ratio of the styrene compound to the polyene compound is about
200 : 1 to 1 : 1, preferably 50 : 1 to 2 : 1.
The styrene compound and the polyene compound are used
for the graft copolymerization reaction as solutions in organic
solvents which uniformly dissolve the styrene compound and the
polyene compound, but do not dissolve the hydrocarbon polymer. -
Examples of suitable organic solvents are ketones such as acetone
or methyl ethyl ketone, esters such as ethyl acetate or butyl ;-
acetate, alcohols such as methyl alcohol, ethyl alcohol, propyl
alcohol or butyl alcohol, ethers such as tetrahydrofuran, aromatic
hydrocarbons such as benzene or toluene, aliphatic or alicyclic
hydrocarbons such as n-heptane or cyclohexane or mixtures thereof.
Because aliphatic or alicyclic hydrocar~ons have high affinity
for the hydrocarbon polymers, they swell the polymers and permit
.:
easy introduction of the monomer. Thus, the grafting reaction is
accelerated, and the grafting becomes uniform. The amount of
these hydrocarbons should be such that they do not dissolve the
polymer at the reaction temperature, and the amount is
determined according to the type of the polymer.
;~ The concentration of the monomer in the reaction solution
~; is not critical, but generally, a suitable concentration of the
monomer is about 0.1 to 80% by weight, preferably 5 to 50~ by
. .
~- weight, based on the weight of the solution.
- ~ , : . . .
The grafting ratio can be varied as desired. From the
view~oint of modifying the hydrocarbon polymer, the grafting
-7 ~
~ ~ .
~o4r7~
1 ratio of the resulting graft copolymer i5 preferably at least
about 0.1% by weight.
The term "grafting ratio", as used herein, means the
weight percent of the amount of the monomers grafted based on
the weight of the hydrocarbon polymer.
The grafting ratio can be determined as desired according
to the type of modification. For example, where improved
dyeability or adhesivene~s of the polymer is desired, subjecting
only the surface of the polymer to graft copolymerization is
sufficient, and therefore, the grafting ratio can be about 0.1%
by weight. For improving reactivity, the grafting ratio is
preferably at least about 10% by ~eight. The upper limit of
the grafting ratio is not critical, but generally the upper limit
is about 200% by weight to obtain feasible results. When the
resulting graft copolymer is used as an ion-exchange membrane
either as such or after introducing a sulfonic acid group,
quaternary ammonium group or quaternary phosphonium group there-
into, the grafting ratio of hydroxystyrene in the graft copolymer
is generally about 5 to 500%. If the grafting ratio is less
~O than about 5%, the polymer exhibits insufficient properties
as`an ion-exchange membrane. If the grafting ratio is above
500%, the strength and softness of the polymer are insufficient,
and it is difficult to use the polymer as an ion-exchange
membrane. The weight ratio of grafting or introducing the poly-
;~ ene compound (based on the hydrocarbon polymer) is generally
- about 0.5 to 100%. If the ratio is less than about 0.5%, cross~
linking is insufficient so that the ion selectivity of the
~polymer is insufficient, and~no outstanding effect is obtained
by incorporation of the polyene compound. On the other hand,
if the ratio is more than about 100%, crosslinking becomes
- 8 -
.
' '~
~0~7~
1 excessive, the polymer generally tends to be hard, brittle and
tearable, and to have a high electric resistance that makes the
passage of electricity through the polymer difficult. In view
of the ion transport number, electric resistance and strength
of the membrane, an especially preferred grafting ratio is
about 20 to 20Q% for hydroxystyrene, and about 2 to 50% for the
polyene compound.
The graft copolymerization in accordance with this
invention is carried out using ionizing radiation. Ionizing ;~
10 radiation leads to the formation of a trapped radical or a polymer
peroxide on the hydrocarbon polymer, and a side chain composed
of the styrene compound and/or the polyene compound is formed
on the above active site. At the same time, a partial cross-
linking by the polyene compound occurs in the polymer. When the
monomeric mixture to be grafted contains an unsaturated compound
such as ethyl vinylbenzene, for example, such an unsaturated
compound is also graft copolymerized and contained in the side
chain. The presence of unsaturated compounds other than the
acylo~ystyrene, hydroxystyrene and polyene compounds especially
20.~monounsaturated compounds other than those havin~ a polymerization
inhibiting action, for example, styrene, l-hexene and acrylic
: :.
acid esters in addition to ethylvinylbenzene does not adversely
affect the copolymerization. However, if the amount of such
an unsaturated compound is too large, the effect of the present
invention is reduced. For practical purposes, therefore, the
~amount of such a compound must be 30~ by weight or less based
on the total amount~of the monomeric mixture.
Thegraft polymerization method usin~ ionizing radiation
includes a pre-irradiation process which comprises sub~ecting a
~- 30 base polymer to ionizing radiation in the absence of monomer, and
9 ~
~:
~ ' . .
i
-~ ~,o~76~
then contacting the polymer with the monomer, and a simultaneous
irradiation process which comprises sub~ecting both a base
polymer and a monomer simultaneously to ionizing radiation. In
the present invention, either of these two methods can be used.
The source of ionizing radiation can be ~-rays, X-rays, electron
beams, a-rays, or mixtures thereof. A suitable intensity, that
is, dose, of the ionizing radiation is about 103 to 1011 rads
per hour. With electron beams, doses of as high as about 109 to
1011 rads per hour can be used. Although lower doses can be used,
10 a long time is required to obtain the desired amount of
irradiation. Furthermore, higher doses can also be used, but
are not feasible because a higher dose may result in a structural
change of the polymer, for example, excessive crosslinking, ~ `
cleavage of the main chain, and deformation and breakage of the ;
polymer by heat.
The use of electron beams generated from an electron
beam accelerator is especially effective since high dose irra-
~diation can be obtained within short periods of time. The totaldose of ionizing radiation required for graft copolymerization
20~;is usually from about 105 rads to;101 rads.
Thè temperature employed for ionizing radiation must be
one at which the hydrocarbon polymer is~ not dissolved and de-
formed. In view o~ the life of the generated radicals (which
is short at high temperatures), a feasible temperature is generally
from -100 C to 40 C. There is no particular lower limit to
thls temperatPre except for economical and technical problems.
According~to the pre-irradiation method, the hydrocarbon
polymer is subjected to ionizing radiatl~on in vacPo or in an
inert gas such as nitrogen, and then the hydrocarbon polymer is
immersed in an organic solvent solution of the styrene compound
,~ . .
~ . :
~:: : . ~`
1 0
~7~
1 and the polyene compound to graft these monomers to the hydro-
carbon polymer.
The graft copolymerization reaction temperature is
generally from the temperature at which the reaction mixture is
liquid, to about 100C. If the reaction temperature is too low,
the time required for the reaction becomes longer, and if it is
too high, gellation or homopolymerization under heat tends to
occur. A suitable temperature can be selected so that such
difficulties do not occur. For practical purposes, temperatures
10 of about 0 to 70C are suitable. Where ionizing radiation is
applied in air, the graft copolymerization is preferably carried
out at a temperature of about 60C or more because the peroxide
generated must be decomposed. Ionizing radiation ih advance
in air or in a stream of nitrogen is commercially advantageous.
When the simultaneous irradiation process is employed,
the hydrocarbon polymer is immersed in an organic solvent
solution containing the styrene compound and the diene compound,
and the solution is subjected to ionizing radiation thereby to
graft the monomers to the hydrocarbon polymer. The same reaction
.. .... .
20 temp~ra-ture as in the pre-irradiation process can be used.
Alternatively, in the process of this invention, the
s~yrene compound alone is first grafted to the hydrocarbon
polymer, and then the polyene compound is grafted thereto, using
ionizing radiation.
The reaction time can be varied over a wide range
according to the properties of the desired graft copolymer, the
dose of irradiation, and the grafting ratio. The reaction time
may sometimes be as short as about 5 to 6 seconds, but in the
case of the pre~irradiation process, more than one month is
30 required.
-
- 11 - , . . .
~ '' ',' .
.
.
:
1 The resulting graft copolymer, if desired, is washed
with an organic solvent, for example, an alcohol such as methanol,
ethanol or propanol, a ketone such as acetone or methyl ethyl
ketone,or an aromatic hydrocarbon such as benzene or toluene, or
mixtures of these. Graft copolymers containing a side chain
comprising the acyloxystyrene group can, if desired, be hydrolyzed
to cOnvert the acyloxy group in the side chain to a hydroxyl
group. This hydrolysis treatment, like an ordinary hydrolysis
of phenol esters, is much easier to perform than the hydrolysis of
10 esters of primary alcohols, and can be carried out easily under
mild conditions. Specifically, the graft copolymer is placed in
a solution of an acid such as hydrochloric acid, sulfuric acid
or an organic sulfonic acid or a base such as sodium hydroxide or
ammonia as a catalyst in water or in a mixture of water and an
organic water-soluble solvent to hydrolyze the acyloxy group at
the side chain. Since the hydrolysis is primarily carried out
in a heterogeneous system, it is preferably performed in a
mixture of water and a water-soluble organic solvent such as
an alcohol or ketone in order to increase the affinity between
20 the substrate and the catalyst and also to dissolve the organic
acid that has been split off in the case of using an acidic
catalyst. The sui-table hydrolysis tempera-ture is about 50 to 1~0C.
In this hydrolysis, the degree of hydrolysis of the acyloxy
group in the side chain can be varied as desired. ~hen the
temperature is elevated and the time is prolonged, the degree of
hydrolysis increases.
According to this invention, a novel graft copolymer ~ i
which has a side chain composed mainly of acylo~ystyrene com-
pounds or hydroxystyrene compounds or a mixture of these compounds
3~ and the polyene compound and a main chain of a hydrocarbon
polymer partially crosslinked with the polyene compound contained
-12 ~
768~L
1 in the side chain can ~e obtained. This graft copolymer has
suitable functional groups in addition to the superior mechanical
properties of the hydrocarbon polymer. Accordingly, the
adhesiveness, dyeability, oxidation resistance or reactivity
with other compounds of the hydrocarbon polymer can be markedly ~`
improved. Graft copolymers containing a side chain comprising
hydroxystyrene groups are especially superior in these properties,
and are especially useful as a material for reactive polymers.
~he ~f~ ~Dpo~y~e~ Ç~ ~hi5 ~n~en~ic~ ~ave better me~hanical
9 an~t chemlcal propertles t~an t`nc~se ~c~ w~` c~ ~y ~c~ s~.y~
compouna o:E the i~ormula ~1) has been grate~.
.i - , ;.:
The gra~t copo~yme~s so obtained can ~e easil~ ~ormed
into film-like fabricated articles of uniform quality and
desired size. In order to produce large-sized membranes of
uniform quality, it is effective to gra~t copolymerize the
hydroxystyrene compound and the polyene compound with a film~like
hydrocarbon polymer.
.
The graft copolymers of this invention are suitable as
packaging films, structural materials such as han~les or rods,
20 and especially as ion-exchange membranes or basic polymer
~matrixes for ion-exchange membranes.
The introduction of a sulfonic acid group into a film-
like graft copolymer having a side chain containing hydroxy-
styrene compounds can be effected by any known sulfonating
;~ method of phenols.~ For example, this can be effected by sulfo-
; nating the graft copolymer with concentrated sulfuric acid,
sulfuric anhydride, or chlorosulfonlc acid, etc. in the presence
or~absence of a solvent. Examples of suitable solv nts which ;
can~be used in this process are halogenated hydrocarbons such
30 as chloroform or carbon tetrachloride, polar solvents such as ~-
:
~ - 13 -
.
,
':: ` ' .
~IL0~7~
pyridine or dimethylformamide r or such solvents as ether or
dioxane. Catalysts such as silvex sulfate can be used in this
process.
When concentrated sulfuric acid is used, the film is
immersed in concentrated sulfuric acid, and allowed to react for
l hour to about lO days at 0 to 40C. If heating is carried out
to a temperature of about 60C, the treating time can be
shortened. If the temperature is too high, the base polymer
is attacked with its properties bein~ degraded. In order to
achieve a reaction mild, up to about 80% by weight of a solvent
such as acetic acid or dioxane can be used. When fuming sulfuric
acid containing about 5 to 60% by weight of sulfuric anhydride
is used, the film is suitably treated at room temperature for
about 2 to lO hours. If the reaction proceeds excessively,
the base polymer is also attacked. Where chlorosulfonic acid
is used, the graft copolymer is dissolved in a solvent such
as chloroform, dioxane, carbon tetrachloride or a mixture of
these in a concentration of about l to 60% by weight, and
reacted at about 0 to 60C for about l hour to lO days. Then,
2~ the reaction product is washed with water. The reaction
conditions such as the temperature, the type of reactant, the
concentration, or the reaction time are controlled as required
so th~at the proportion of sulfonic acid groups introduced becomes
the desired value.
The introduction of a quaternary ammonium group can be
effected by using~a known method of introducing a quaternary
ammonium group into hydroxystyrene. Suitable quaternary ammonium
~ groups are generally those introduced into an ion-exchange
; membrane and the N-substituents thereof suitably contain up to -
.
30~ about 20 carbon atoms. Specifically, the graft copolymer is
', ~ ': '
;~ ' ' ':
-
~04~
.
first reacted with a secondary amine and an aldehyde reactant
suchas formaldehyde or paraformaldehyde in a suitable solvent
~Mannich reaction) to form a graft copolymer in which the hydroxy
styrene side chain is tertiary-aminomethylated. Examples of
suitable solvents used in this method are alkali aqueous
solutions, alcohols such as methanol, ethanol, propanol or butanol,
or polar solvents such as tetrahydrofuran. Examples of suitable
secondary amines are amines such as dimethylamine, diethylamine,
dipropylamine, diisopropylamine, diallylamine, dibutylamine,
10 diphenylamine or N-methylaniline, heterocyclic amine compounds
such as pyrrole, pyrrolidine, imidazole, indole, piperidine
or morpholine, and dialkanol amines such as diethanol amine, or
dipropanol amine. The molar ratio of the secondary amine to
the aldehyde reactant is desirably about 3 : 2 to 2 : 3. The
ratio of these to the graft copolymer is adjusted according to
the desired ratio of the aminomethyl group introduced. A
suitable reaction temperature used in this reaction is about 0
to 200C, preferably 15 to 150C. Usually, the reaction is
carried out for about 10 to 50 hours. A quaternary ammonium
20 group is introduced into the resulting tertiary aminomethylated
graft copolymer using an organic halide or a dialkyl sulfate,
etc. The halide used in this process can be monohalides, for
example, alkyl halides (chlorides, bromides or iodides, etc.) -
containing 1 to 20 carbon atoms, alkenyl halides, substituted
or unsubstituted benzyl halides, halogena-ted acetic acid, or -~
halohydrins. The tertiary aminomethyl group introduced into the
; graft copolymer is quaternized by such a monohalide. Dihalides,
for example, dihalides containing an alkyl group with ~ to 6 -
carbon atoms (for example, 1,2-dibromoethane or l,~-dibromobutane),
30 dihalides containing an ether group (for example,~,~'dichloro-
,
~: '
' ~
.
:, .. : .. . ..
~L0~6~
diethyl ether), or dihalides containing a phenyl group tforexample,~,~'~dichloro-p-xylene~, and epihalohydrins can also
be used. This quaternization reaction is carried out usually
at a temperature of about 15 to 150C in the presence of a
solvent selected, for example, from alcohols, ketones, tetra-
hydrofuran, dimethylformamide, dimethyl sulfoxide, and hexa-
methyl phosphoric triamide according to the t:ype of the halide
or dialkyl sulfate used. The concentration of the reagent is
determined by, for example, the rate of reaction and the
solubility, but generally, it is used in a concentration of
about S to 100% by weight based on the material to be reacted.
The reaction easily proceeds quantitatively.
Further, the introduction of the quaternary ammonium
group can also be effected by chloromethylating the hydroxy-
styrene of the graft copolymer followed by quaternizing the
resulting chloromethylated hydroxystyrene with an amine as
illustrated below.
f_CH-CH2~r t--~-CH2--t '
~ ~ ~ Chloromethyl-ether ~ ~ ChRCQ J ~:~
f CH-CN2 -- \ , .
NR R R 1 R12
CH2-N - R13 )
n CQ~ ;
~ wherein R and n are defined hereinbefore, and R12, R13 and R14,
- 30 which may be the same or different, represent the same substituents
as defined for the compounds enumerated as examples for the above
described secondary amines, and halides.
~: .
- 16 -
.:
. .
1 The introduction o the quaternary phosphonium group can --
be carried out by chloromethylating hydroxystyrene of the graft
copolymer followed by quaternizing the resulting chloromethylated
hydroxystyrene with a trivalent phosphoric compound having the
formula P[NR15R16] wherein R15 and R16 are as defined below as
illustrated below.
~,~CH2 ~ ~C112t
~ ~ J Chloromethyl-ether \ ~ J
7~ CH2 . \ ,
P[NR 5R ] ~ ~ ~ NR15R16
(OR)n NR
CQe ' ' - .
wherein R and n are defined hereinbefore, and RlS and R16 each -~
represents an alkyl or alkylaryl group having 1 to 20 carbon ~
~!0 ~"""
atoms. Trivalent phosphoric compounds containing an ethyl group
in the alkyl moiety thereof are generally employed.
By the above kreatment of introducing ion-exchange
groups, the ion-exchange groups are introduced mainly into
hydroxystyrene groups at the side chain of the yraft copolymer,
but can also be introduced into other parts of the side chain
without exerting any adverse effect.
In the ion-exchange group introducing treatment, the
number of ion-exchange groups to be introduced per unit of the
mono- or dihydroxystyrene in the side chain can be adjusted as
desired by selectiny the reaction conditions. A suitable number
- 17 -
. - : ~. :
~0~76B~L
of ion-exchange groups is about 0.5 to 2 per unit of the mono-
or dihydroxystyrene, preferably 1 to 2 from the standpoint of the
electric resistance and the ion selectivity of the resulting
product.
In the case of sulfonation, about one sulfonic acid
group is introduced per unit of the mono- or dihydroxystyrene
if the graft copolymer is treated with concentrated sulfuric acid
at room temperature for about 10 hours. When a strong sulfonating
agent such as chlorosulfonic acid is used, the treatment of the
10 polymer in a solution of chloroform or dioxane, etc. results in
the introduction of about 2 sulfonic acid groups per unit of
the mono- or dihydroxystyrene, and a membrane having a hi~h
ion-exchange capacity can be obtained. On the other hand, when
the graft copolymer is tertiary-aminomethylated and subsequently
quaternized, l to 2 tertiary aminomethyl groups can be introduced
per unit of the mono- or dihydroxystyrene by controlling the
reaction conditions such as the reaction temperature and
pressure at the time of the aminomethylation,and the ratios of
the secondary amine and the aldehyde reactant fed to the graft
20 copolymer. The number of tertiary aminomethyl groups increases
with higher reactlon temperature and pressure and higher ratios
to be charged.
Ion-exchange membranes obtained in the above manner have
good electrical and chemical properties and superior mechanical
strength and durability and also superior chemical stability
such as resistance to solvents or resistance to alkalis.
Accordingly, they are usefuI as electrodialysis membranes for
concentration and desalination of sea water. Furthermore, the
ion-exchange membranes in accordance with this invention have
30 improved characteristics at elevated temperatures and can endure
- 18 -
,, , . .:
use under more severe conditions than the conventional ion-
exchange membranes which were proposed earlier by the inventors
of the present application and which were prepared rom a graft
copolymer consisting of a polyolefin main chain without a
crosslinked structure ascribable to a polyene compound to
which a hydroxystyrene side chain is grafted.
The following Examples are given to illustrate the
present invention further, but are not to be construed as
limiting in any way the scope of the present invention. Unless
otherwise indicated, all parts, percents, ratios and the like
are by weight.
EXAMP~E 1
~: .
One leg of a glass H-type cell (diameter 10 mm, thickness
0.5 mm) was charged with a 0.1 mm thick polyethylene film
washed thoroughly with acetone and the other leg was charged ;
with a solution of a mixture of ~-acetoxystyrene and divinyl- ;~
benzene (commercial grade, containing 55% by weight of ~-
divinylbenzene with an m- to p-weight ratio of about 2 : 1,
and the remainder being mainly ethylvinylbenzene, hereinafter
the same3 in a weight ratio (p-acetoxystyrene : divinylbenzene)
of 9 : 1 in two times its weight of a mixture of benzene and
acetone (in a benzene : acetone ~olume ratio of 3 : 1). By
repeating afreezing-melting procedure 5 times, the cell was
thoroughly degassed ln vacuo, and then heat-sealed. The monomer
` solution part was frozen, and sufficiently covered with a lead
pl~ate. While the~entire H-type cell was being cooled at -30C,
electron ~eams in a dose of 30 M rads were applied to the
polyethylene film at an acceleration voltage of l.S MeV using
an electron beam accelerator. After the irradiation, the
monomer solution was trans~erred to the film-containing portion
..
- 19 -
.. :.
~(~i4~6~3~
to dip the film in the solution and allow it to react for 24
hours at 25C. After the reaction, the cell was opened. The
film was withdrawn, thoroughly washed with benzene and acetone,
and dried at reduced pressure until its weight became constant.
The total grafting ratio calculated from the difference in weight
before and after the reaction of the film was 118%. The
resulting film did not change further in weight even when
repeatedly washed with acetone and benzene. -
The infrared absorption spectrum of the film obtained ;
contained a strong absorption characteristic of an ester in
the vicinity of 1770 cm 1 and 1200 cm 1 and an absorption -
characteristic of aromatics in the vicinity of 1615 cm 1 and
1515 cm 1 in addition to an absorption inherent to polyethylene. -~
From this, it is clear that p-acetoxystyrene was grafted to the
polyethylene.
The film obtained was placed in a 100 ml flask equipped
with a cooling tube. Then, 50 ml of a mixture of concentrated -
hydrochloric acid and methanol in a mixing ratio by weight of -
1 : 4 was added, and the flask was heated for 30 minutes over
a hot water bath. The resulting film was examined by infrared
absorption spectroscopy. It was found that the ester group was
completely hydrolyzed, and an absorption based on a phenolic
hydroxy group was newly observed.
The film was dried at reduced pressure until its welght -
became constant. The totaI grafting ratio calculated from the
diffeIence in weight before and after th~reaction of the film
was 95.3%. The grafting ratio of p-acetoxystyrene alone cal-
culated from the difference in weight of the film before and
after the hydrolysis reaction was 87.3%. Thus, the grafting
ratio of divinylhenzene was calculated as 30.7~. The results of
quantitative analysis of the~phenolic hydroxyl group by re-
: - .
- 20 -
'~
~.~476~
~: acetylation and neutralization of the hydrolyzed film and the . :~
values determined by the elemental analysis corresponded
substantially with those obtained above.
EXAMPLE 2
A graft copolymerization was carried out in the same
manner as described in Example l except that the weight ratio of
p-acetoxystyrene : divinylbenzene fed was changed to 15 : 1. ~ ~ :
The total grafting ratio calculated from the increase in weight
of the resulting grafted film was 82%. The grafted film was
1 0
hydrolyzed in the same manner as described in Example 1. The
total grafting ratio of the graft film became 64.9%. The graft-
ing ratios of p-acetoxystyrene and divinylbenzene as measured :~-
from the difference in wei.ght of the film before and after the
hydrolysi.s were 69.0% and 13,0%, respectively.
EXAMPLE 3 ` :
A graft copolymerization reaction was carried out except
that the weight ratio of p-acetoxystyrene : divinylbenzene fed
was changed to ~ : l. The total grafting ratio calculated from
the increase in weight of the grafted film was 98.6~. The
grafted film was hydrolyzed in the same manner as described in
Example l. The total grafting ratio became 85.8%. The
grafting ratios of p-acetoxystyrene and divinylbenzene calculated
from the difference in weight of the grafted film before and
after the hydrolysis were 49.3% and 49.3%, respectively.
EXAMPLE 4
A graft copol~merization was carried out in the same
: manner as described in Example l except that the dose of electron ~`
- beams was changed to 20 M rads. The total grafting ratio .:.~: 30 .:: -
calculated from the increase in weight of the grafted film was 68%. :::
- 21
..:
'
3 This film was hydrolyzed in the same manner as described in
Example 1. The total grafting ratio hecame 55.0%. The grafting
ratios of the p-acetoxystyrene and divinylbenzene calcu]ated
from the difference in weight of the grafted film before and
after the hydrolysis were 50.3-~ and 17.7%, respectively.
EXAMPLE 5
A graft copolymeri2ation was carried out in the same
manner as described in Example 1 except that a 0.1 mm thick
polypropylene film was used as a base polymer. The total graft-
ing ratio calculated from the increase in weight of the resulting
grafted film was 119.4%. The film was hydrolyzed in the same
way as in Example 1. The total grafting ratio became 96.5%.
The grafting ratios of p-acetoxystyrene and divinylbenzene
calculated from the difference in weight of the grafted film
before and after the hydrolysis were 88.4% and 31.0~, respectively.
EXAMPLE 6
: ~:
~ graft copolymerization was carried out in the same
manner as described in Example 1 except that polypropylene
2~ powder was used as the base polymer. The total grafting ratio
calculated from the increase in weight of the grafted powder
was 67.2%. The grafte~ powder of polypropylene was hydrolyzed
in the same manner as described in Example 1. The total graft-
ing ratio became 54.3%. The grafting ratios of p-acetoxystyrene
and divinylbenzene calculated from the difference in weight of
- the grafted polypropylene powder before and after the hydrolysis
were 49.7% and 17.5%, respectively.
EXAMPLE 7
A 0.1 mm thick polyethylene film was cooled to -20C, and
3~
irradiated with electron beams in a dose of 30 M rads in air.
- 22 -
':
.. 10~76~
The film was then placed in a glass ampoule, and a solution of
a monomeric mixture of p-acetoxystyrene and divinylbenzene in a
weight ratio (p-acetoxystyrene : divinylbenzene) o 9 : 1 in
two times its weight of a mixture of benzene and acetone in a
benzene : acetone mixing ratio by weight o~ 3 : 1 was introduced
into the ampoule. The ampoule was thoroughly degassed 1n vacuo
by repeating a freezing-melting procedure ive times, and then
heat~sealed. The ampoule was placed in a constant temperature
vessel at 70C, and the film was allowed to react for 3 hours.
After the reaction, the ampoule was opened, and the film was
withdrawn. The film was thoroughly washed with benzene and
acetone, and dried at reduced pressure until its weight became
constant. The total grafting ratio calculated from the increase
in weight ofthe grafted film was 30.5%. The grafted film was
hydrolyzed in the same manner as described in Example 1. The
total grafting ratio became 24.4%. The grafting ratios of p-
acetoxystyrene and divinylbenzene calculated from the difference
in weight of the grafted film before and after the hydrolysis
weré 23.5% and 7.0%, respectively.
EXAMPLE 8
.
A 0.1 mm thick polyethylene ilm was placed in a glass
ampoule, and a solution of a monomeric mixture of p~acetoxy- -
st~rene and divinylbenzene in a weight ratio (p-acetoxystyrene:
divinylbenzene) of 9 : 1 in 9 times its weight of a mixture of
benzene and acetone in a benzene : acetone volume ratio of 3
~was placed in the ampoule. The ampoule was sufficiently
de~assed in vacuo by repeating a freezing-melting procedure
five times and then heat-sealed. Using a cobalt 60 source, y-
rays were applied to the ampoule at a dose of 1.1 x 10 rads/hourat 20 to 25C for 24 hours. ~hen, the ilm was taken out of the
.~ . .
. .
~ - 23 -
.
~ : .
6~
1 ampoule, washed sufficiently with benzene and acetone to remove
a by-product copolymer composed of p-acetoxystyrene and
divinylbenzene, and then dried. The total grafting ratio
calculated from the increase in weight of the grafted -film was
79%. The grafted film was hydrolyzed in the same manner as
described in Example 1. The total grafting ratio became 64.7~.
The grafting ratios of p-acetoxystyrene and divinylbenzene
calculated from the difference in weight of the grafted film
before and after the hydrolysis were 55~3% and 23.7~, respectively.
EXAMPLE 9
A graft copolymerization was carried out in the same
manner as described in Example 1 except that p-hydroxystyrene
was used instead of the p-acetoxystyrene. The total grafting
ratio ¢alculated from the increase in weight of the resulting ;
grafted film was 5.9%. The grafted film was acetylated using
acetic anhydride and sodium acetate. From the acetylation value
of the grafted film so determined, the grafting ratios of p-
hydroxystyrene and divinylbenzene were found to be 4.8% and
:
1.1%, respectively. -
~0 : -~
The grafting ratios of p-hydroxystyrene and divinylbenzene
of this grafted film which were calcula-ted from elemental
analysis values of the grafted film and the acetylated film
substantially corresponded with the above values.
EXAMPLE 10 ~ ;
~A graft copolymerization was carried out in the same
;manner as described in Example 1 except that isoprene was used ~-
instead of the divinylbenzene. The total grafting ratio
calculated from the weight increase of the grafted film was
;30 28.6~. The grafted film did not further change in weight even - ;
~when extracted with acetone and benzene. The film was hydrolyzed
'':
~- 24 -
, .
: . : .
613~
in the same manner as described in Example 1. The total grafting
ratio became 21.6%. The grafting ratios of p-acetoxystyrene and
isoprene determined from the difference in weight of the grafted
film before and after the hydrolysis were 27.0% and 1.6%,
respectively. ;
EXAMPLE 11
In the same manner as described in Example 1, one leg
of an H-type cell was charged with a 0.1 mm thick polyethylene
film and the other leg was charged with a solution of a monomeric
mixture of p-hydroxystyrene, p-acetoxystyrene and divinylbenzene
in a weight mixing ratio of ~.5 : 4.5 : 1 in two times its
weight of a mixture of benzene and acetone at a benzene : acetone
mixing ratio by volume of 3 : 1. The cell was dega.ssed l.n vacuo, ..
and heat-sealed. Electron beams were applied to the poly-
ethylene film in yacuo in a dose of 30 M rads. After the
irradiation, the monomer solution was transferred to the film~
containing portion, and the film was reacted for 24 hours at .. : .
20C. After the reaction, the film was taken out, washed
thoroughly with acetone and benzene, and dried at reduced :~
pressure until its weight became constant. The total grafting
ratio calculated from the difference in weight of the film .. :.
before and after the reaction was 6~. The film was acetylated,
and from the acetylation value obtained, the grafting ratio of
p-hydroxystyrene was calculated as 4.3%. The film was .-
hydrolyzed, and the grafting ratios of p-acetoxystyrene and
divinylbenzene were calculated from the difference in weight of :
: the film ~efore and after the hydrolysis and found to be 47.8%
and 11.9%, respectively.
EXAMPLE 12
A graft copolymerization was carried out in the same ~ :
- 25 - ~
~.
t manner as described in Example 1 except that a 0.1 mm thick
polystyrene film was used as a base polymer, and a mixture of
methanol and benzene in a volume ratio ~methanol : benzene) of
2 : 1 was used as a solvent. The total grafting ratio calculated
from the weight increase of the grafted film was 54.1%. When
this grafted film was hydrolyzed, the total grafting ratio
became 45.6%. The grafting ratios of p-acet.oxystyrene and
divinylbenzene determined from the difference in weight of the
grafted film before and after the hydrolysis were 32.6% and -
21.5%,respectively.
EXAMPLE 13 ~ :
A graft copolymerization was carried out in the same :
manner as described in Example 1 except tha-t m-acetoxystyrene
was used instead of the p-acetoxystyrene. The kotal grafting
ratio of the grafted film calculated from the weight increase .
of the film was 92.3%. When this film was hydrolyzed, the total
.
grafting ratio became 74.4%. The grafting ratios of m acetoxy-
styrene and divinylbenzene determined from the difference in
weight before and after the hydrolysis were 57.1% and 35.2%, .
respectively.
EXAMPLE 14
One leg of a glass H-type cell (diameter 10 mm, thickness . .
0.5 mm~ was charged with a 0.1 mm thick polyethylene film washed
thoroughly with acetone and the other leg was charged with a .-
solution of a monomeric mixture of p-acetoxystyrene and divinyl-
benzene ~commercial grade, containing 55% by weight of divinyl-
benzene with the remainder being mainly ethylvinylbenzene) in
a weight ratio (p-acetoxystyrene :divinylbenzene) of 20 : 1 in
30 2 times its weight of a mixture of benzene and acetone in a
':
- 26
7~
benzene : acetone volume ratio of 3 : 1. The cell was sufficiently
degassed in vacuo by repeating a freezing-melting procedure
five times, and heat-sealed. The monomer solution part was
frozen, and sufficiently covered with a lead plate. While the
entire cell was being cooled to -30C, electron beams were
applied to the polyethylene Eilm _ vacuo in a dose ~f 30 M rads
at an acceleratin~ voltage of 1.5 MeV using an electron
accelerator. After the irradiation, the monomeric solution was
transferred to the film-containing portion, and the film was -
reacted for 24 hours at 25C. After the reaction, the cell
was opened,and the film was taken out. Then, the film was
thoroughly washed with acetone and benzene, and dried at reduced
pressure until its weight became constant. The re;ulting film
had a total grafting ratio of 68.8% as calculated Erom the
difference in weight before and after the reaction.
The film was heated under reflux in a 1 : 4 mixture by
weight of concentrated hydrochloric acid and methanol for 30
minutes to hydrolyze it. The resulting film was one in which
p-hydroxystyrene and divinylbenzene were grafted to the base
polymer. The total grafting ratio calculated from the
difference in weight before and after the reaction was 56.1%,
and the grafting ratios of p-hydroxystyrene and divinylbenzene
calculated from the difference in weight of the film before
and after the hydrolysis were 51.1% and 5.0~, respectively.
The film was dipped for 10 hours in a 1 : 1 (by weight)
mixture o~ chlorosulfonic acid and dioxane at 50C, then with-
drawn, and washed with water. The resulting film had an ion-
exchange capacity of 2.35 meq/g (when dry), an electric resistance,
as measured in a 0.5~ aqueous solution of sodium chloride, of
1.3 Qcm2, and an ion transport number, according to a membrane
~ ~ .
- 27 -
1 potential method, of 0.99. I~hen wet, this film had a tensile
strength of l.l Kg/mm .
EXAMPLE 1 5
A 0.1 mm thick polyethylene film was subjected to graft
copolymerization in the same manner as described in Example 14.
The grafting ratio of m-hydroxystyrene was 49~7%, while the
grafting ratio of divinylbenzene was 8.4~. The grafted film
was immersed for lO hours in a 1 : 1 (by weight) mixture of
chlorosulfonic acid and dioxane at 50C, withdrawn, and washed
with water. The resulting film had an ion-exchange capacity; ~: -
of 2.22 meq/g (when dry), an electric resistance of 0.8 Qcm2,
an ion transport number of 0.98, and a tensile strength of 1.3
Rg/mm2 (when wet). ~;
EX~MPLE 16 ` .
A 0.1 mm thick polyethylene film was subjected to graft
copolymerization in the same manner as described in Example 14O
The grafting ratio of p-hydroxystyrene was 20%, while the
grafting ratio of isoprene was 1.6%. The grafted film was
allowed to stand in 96~ concentrated sulfuric acid at room
temperature for 24 hours, withdrawn, and washed with water.
The resulting film had an ion-exchange capacity of 1.14 meq/g :
(when dry), an electric resistance of 4.5 Qcm2, an ion trans-
~ port number of l.0 and a tensile strength of 1.0 Kg/mm2 (when . ;
:~ wet).
EXAMPLE 17 . .
A grafted film which was obtained in the same manner as
described in Example 14 and in which the grafting ratio of p-
: hydroxystyrene was 51.1%, and the grafting ratio of divinyl~
benzene was 5.0% was immersed in a mixture of 3.1 g of para-
i ~ .
- 28 - .
, .
formaldehyde, S.4 g of dimethyl amine and 70 ml of ethanol, and
reacted at 85 to 90C to dimethylaminomethylate the polymer.
The resulting dimethylaminomethylated product was immersed in an
ethanol solution containing 10% of methyl bromide to react the
product for 40 hours at 25C. The reaction product was with~
drawn, and thoroughly washed with ethanol. The film obtained
had an ion-exchange capacity of 2.42 me~/g, an electric
resistance of 2.3 ~cm2, an ion transport number of 0.99 and a
tensile strength of 0.9 Kg/mm .
EXAMP~E 18
One leg of the same ~-type cell as used in Example 14
was charged with a 0.1 mm thick polypropylene film and the other
leg was charged with an acetone-benzene solution (cL benzene :
acetone mixing ratio by volume of 2 : 1) containincl 20~ by
weight of p-acetoxystyrene. The cell was fully degassed ln
vacuo by repeating a freezing-melting procedure five times,
and then heat-sealed. The monomer solution part was frozen
and fully covered with a lead plate. While the entire H-type
cell was being cooled at -30C, the polypropylene film in vacuo
2~
was subjected to the irradiation of electron beams at a
dose of 10 M rads. After the irradiation, the monomer solution
was transferred to the film-containing portion, and reacted
at 20C for 24 hours. After the reaction, the film was taken
out, washed thoroughly with acetone and benzene, and dried at
reduced pressure until its weight became constant. The grating
ratio of p-acetoxystyrene in the resulting film, as calculated
from the difference in weight before and after the reaction,
was 87.6%.
The film was further ptaced in one leg of another H-type
cell, and an acetone-benzene mixed solution ~ a benzene : acetone
,. ' .
- 2~ -
~ 7~
volume ratio of 2 : 1~ containing 10% by weight of divinyl-
benzene was placed in the other leg of the cell~ and the cell was
heat-sealed in vacuo. In the same manner as described above,
the film in vacuo was subjected to the irradiation of electron
beams at a dose of 10 M rads. After the irradiation, the
monomer solution was transferred to the film-containing portion,
and reacted at 20C for 24 hours. The grafting ratio of divinyl-
benzene in the resulting film, as calculatecl from the difference
in weight before and after the reaction, was 21~.
The film obtained was hydrolyzed by heating it under
reflux for 30 minutes in a 1:4 by volume mixture of concentrated
hydrochloric acid and methanol. The hydrolyzed film was
fllrther immersed for 10 hours in a 1:1 by weight chlorosulfonic
a/_id:dioxane mixed solution at 50C, withdrawn, and then washed
with water. The resulting film had an ion-exchange capacity
of 2.24 meq/g (when dry), an electric resistance of 5.6 Qcm2,
an ion transport number of 0.99, and a tensile strength of
2.7 Xg/mm2 (when wet).
EXAMPLE 19 :!.: ,.,.''', .
A 0.1 mm thick polystyrene film was subjected to the
same graft copolymerization and hydrolysis as in Example 14
except that a 2 : 1 by volume mixture of methanol and benzene
was used as a solvent to form a grafted film in which the graft- -
ing ratio of p-hydroxystyrene was 55.2% and the grafting ratio
of divinylbenzene was 6.5%. The grafted film was allowed to
stand in 96% concentrated sulfuric acld at room temperature
for 24 hours, withdrawn, and then washed with water. The film
obtained had an ion-exchange capacity of 2.25 meq/g ~when dry),
an electric resistance of 4.8 Qcm , a cation transport number of
0.9R and a tensile strength of 0.5 Kg/mm2 (when wet).
_ 30 ~
61~
EXAMPLE 20
A graft copolymeriza-tion was carried out in the same
manner as described in Example 1 except that 3,4-diacetoxystyrene
was used instead of p-acetoxystyrene. The resulting graft co-
polymer was found to have a total grafting ratio of 105% and
the grafting ratios of 3,4-diacetoxystyrene ancl divinylbenzene
of 85% and 20%, respectively, as determined hy the same method ;
as described in Example 1.
EXAMPLE 21
A graft copolymerization was carried out in the same
manner as described in Example 1 except that polypropylene was
used instead of polyethylene and 3,4-diacetoxystyrene was used
instead of p-acetoxystyrene. The resulting graft copolymer
was found to have a total grafting ratio of 105% and the
grafting ratios of 3l4-diacetoxystyrene and divinylbenzene of
87~ and 22%, respectively, as determined by the same methods
as described in Example 1.
EX~MPI.E 22
A graft polymerization was carried out in the same
manner as described in Example 1 except that a polypropylene
powder havlng an average particle size of 100 ~ was used instead
of polyethylene and 3,4-diacetoxystyrene was used instead of p-
acetoxystyrene. The resulting graft copolymer was found to
have a total grafting ratio of 62% and the grafting ratios of
3,4-diacetoxystyrene and divinylbenzene of 44% and 18%, res-
pectively, as determined by the method described in Example 1.
.- .:
EXAMPLE 23
A graft copolymerization was carried out in the same
manner as described in Example 7 except that 3,4-diacetoxystyrene
: ~ ' ~'' '
- 31 -
;` :
,
1 was used instead of p-acetox~styrene. The resulting graft
copolymer was found to have a total grafting ratio of 28% and
the grafting ratios of 3,~-diacetoxystyrene and divinylbenzene
of 20% and 8%, respectively, as determined by the method
described in Example 1.
EXAMPLE 24
A graft copolymeriæation was carried out in the same
manner as described in Example 1 except that 3,4-diacetoxy-
styrene and isoprene were used instead of the p-acetoxystyrene
1 0 ' "' ''
and divinylbenzene, respectively. The total grafting ratio
calculated from the increase in weight of the resulting
grafted film was ~.5%. The grafted film was acetylated using ;
acetic anhydride and sodium acetate. From the acetylation
value of the grafted film so determined, the grafting ratios
of 3,4-dihydroxystyrene and divinylbenzene were found to be
3.7% and 0.8%, respectively.
EXAMPLE 25
A graft copolymerization was carrled out in the same
manner as described in Example 1 except that isoprene was used
instead of the divinylbenzene. The total grafting ratio
calculated from the weight increase of the grafted film was
23%. The grafted film was hydrolyzed in the same manner as
described in Example 1. The grafting ratios of 3,4-diacetoxy-
styrene and isoprene determined from the difference in weight
of the grafted film before and after the hydrolysis were 22%
and 1%, respectively.
EXAMPLE 26
~A graft copolymerization was carried out in the same
manner as described in Example 1 except that divinyl~enzene
~-
- 32 -
::.,'.'
.
.: '
~L7~
' 1 containing 90% by weight of divinylbenzene was used instead
of the divinylbenzene containing 55% by weight of divinylbenzene
and that 3,~-diacetoxystyrene was used instead of p-acetoxy
styrene. The total grafting ratio calculated from the increase
in weight of the resulting grafted film was 112%. The grafted
film was hydrolyzed in the same manner as described in Example
1. The grafting ratios of 3,4-diacetoxystyrene and divinyl-
benzene as measured from the difference in weight of the
film before and after the hydrolysis were 83% and 29%, res-
pectively,
EXP~lPLE 27
,
A graft copolymerization was carried out in the same
manner as described in Example 8 except 3,~-diacetoxystyrene
was used instead of p-acetoxystyrene. The total grafting ratio
of the grafted film calculated in the same manner as described
in Example l,was 75%. The grafting ratios of 3,4-diacetoxy-
styrene and divinylbenzene were 54% and 21%, respectively.
EXAMPLE 28
.
The graft copolymer prepared as described in Example -
27 was dipped in a chlorosulfonic acid-dioxane solution
(1:5 by weight) at a temperature of 50C for 5 hours for
sulfonat,ion reaction. As a result of an elemental analysis -~
of the reaction product and the determination of the weight ; ~
~; increase of the grafted film, the sulfonic acid groups '~' '
introduced was found to be 12% by weight based on the graft
copolymer.
EXAMPLE 29
' ~:
; A graft copolymerization was carried out in the same
3~ manner as desc~ribed in Example 1 except that the welght ratio ,-
~.
- 33 ~
,'
7~
of p-acetoxystyrene : 3,4-diacetoxystyrene : divinylbenzene
fed was changed to 6 : 3 : 1. The total grafting ratio cal-
culated from the increase in weight of the resulting grafted
film was 130%. The grafted film was hydrolyzed in the same
manner as described in Example 1. The grafting ratios of
(p-acetoxystyrene ~ 3,4-diacetoxystyrene) and divinylbenzene
as measured from the difference in weight of the film before
and after the hydrolysis were 93.9% and 36.1%, respectively.
EXAMPLE 30
One leg of the same H-type cell as used in Example 1
was charged with a 0.1 mm thick polyethylene film and the other
leg was charged with an acetone-benzene solution (a benzene:
acetone mixing ratio by volume o 2:1) containing 20~ by
weight of 3,~-diacetoxystyrene. The cell was fully degassed
in vacuo by repeating a freezing-melting procedure five times,
and then heat-sealed. The monomer solution part was frozen
and fully covered with a lead plate. While the entire H-type
cell was being cooled at -30C, the polyethylene film in vacuo
~O was subjected to the irradiation of electron beams at a
dose of 10 M rads. After the irradiatlon, the monomer solution
was transferred to the film-containing portion, and reacted
at 20C for 24 hours. After the reaction, the film was taken
out, washed thoroughly with acetone and benzene, and dried
at reduced pressure until its weight became constant. The
grafting ratio of 3,~-diacetoxystyrene in the resulting film,
as calculated from the difference in weight before and after
the reaction, was 89.5~.
The film was further placed in one leg of another H-type
cell, and an acetone-benzene mixed solution (a benzene:acetone
volume ratio of 2:1~ containing 10~ by weight of divinylbenzene
:,
, - 3~
~76~
was placed in the other leg of the cell, and the cell was heat-
sealed ln vacuo. In the same manner as described above, the
film in vacuo was subjected to the irradiation of electron beams
at a dose of 10 M rads. After the irradiation, the monomer
solution was transferred to the film-containing portion, and
reacted at 20C for 24 hours. The grafting ratio of divinyl-
benzene in the resulting film, as calculated from the difference
in weight before and after the reaction, was 27~.
The film obtained was hydrolyzed by heating it under
reflux for 30 minutes in a 1 : 4 by volume mixture of con-
centrated hydrochloric acid and methanol. The hydrolyzed film
was further immersed for 10 hours in a 1 : 1 by weight
chlorosulfonic acid-dioxane mixed solution at 50C, withdrawn,
and then washed with water. The resulting film had an ion-
exchange capacity of 2.80 meq/g (when dry) and an electric
resistanae of 5.1 ~cm2.
While the invention has been described in detail and
with reference to specific embodiments thereof, it will be ~ ~
apparent to one skilled in the art that various changes and -
20 modifications can be made therein without departing from the ~ -
spirit and scope thereof.
'' '"
.
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