U.S. patent application number 09/772971 was filed with the patent office on 2001-09-06 for production process for vinylpyrrolidone polymer.
Invention is credited to Harada, Nobuyuki, Kuriyama, Toshiaki, Naka, Akio, Nishibayashi, Hideyuki, Shimasaki, Yuuji, Tomihisa, Daijo.
Application Number | 20010020078 09/772971 |
Document ID | / |
Family ID | 18558561 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010020078 |
Kind Code |
A1 |
Tomihisa, Daijo ; et
al. |
September 6, 2001 |
Production process for vinylpyrrolidone polymer
Abstract
The present invention provides a production process for a
vinylpyrrolidone polymer which process prevents the polymerization
reaction of N-vinylpyrrolidone from being hindered by by-products
(as formed by nucleomethylation of N-vinylpyrrolidone) or
.gamma.-butyrolactone, and therefore enables to obtain a
vinylpyrrolidone polymer that has a desired molecular weight and
involves only a small amount of residual monomers, wherein the
vinylpyrrolidone polymer can display excellent properties even if
the vinylpyrrolidone polymer is, for example, crosslinked to
convert it into a water-absorbent resin. The production process for
a vinylpyrrolidone polymer comprises the step of polymerizing a
polymerizable monomer component or components which include
N-vinylpyrrolidone, wherein: the N-vinylpyrrolidone as used is
N-vinylpyrrolidone having a .gamma.-butyrolactone content of not
more than 500 ppm; and/or the N-vinylpyrrolidone as used is
N-vinylpyrrolidone obtained without using acetylene as a raw
material.
Inventors: |
Tomihisa, Daijo; (Osaka,
JP) ; Harada, Nobuyuki; (Osaka, JP) ; Naka,
Akio; (Osaka, JP) ; Kuriyama, Toshiaki;
(Osaka, JP) ; Shimasaki, Yuuji; (Otsu-shi, JP)
; Nishibayashi, Hideyuki; (Kobe-shi, JP) |
Correspondence
Address: |
ROYLANCE, ABRAMS, BERRO & GOODMAN
1300 19TH STREET, N.W.
SUITE 600
WASHINGTON,
DC
20036
US
|
Family ID: |
18558561 |
Appl. No.: |
09/772971 |
Filed: |
January 31, 2001 |
Current U.S.
Class: |
526/264 ;
526/258; 526/263 |
Current CPC
Class: |
C08F 226/10 20130101;
C08F 26/10 20130101; C08F 226/10 20130101; C08F 216/125
20130101 |
Class at
Publication: |
526/264 ;
526/258; 526/263 |
International
Class: |
C08F 026/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 2000 |
JP |
2000-34191 |
Claims
What is claimed is:
1. A production process for a vinylpyrrolidone polymer, comprising
the step of polymerizing a polymerizable monomer component or
components which include N-vinylpyrrolidone, wherein the
N-vinylpyrrolidone as used is N-vinylpyrrolidone having a
.gamma.-butyrolactone content of not more than 500 ppm.
2. A production process for a vinylpyrrolidone polymer, comprising
the step of polymerizing a polymerizable monomer component or
components which include N-vinylpyrrolidone, wherein the
N-vinylpyrrolidone as used is N-vinylpyrrolidone obtained without
using acetylene as a raw material.
3. A production process for a vinylpyrrolidone polymer according to
claim 1, wherein the N-vinylpyrrolidone is N-vinylpyrrolidone
obtained by carrying out a gas phase dehydration reaction of
N-hydroxyethylpyrrolidon- e.
4. A production process for a vinylpyrrolidone polymer according to
claim 2, wherein the N-vinylpyrrolidone is N-vinylpyrrolidone
obtained by carrying out a gas phase dehydration reaction of
N-hydroxyethylpyrrolidon- e.
5. A production process for a vinylpyrrolidone polymer according to
claim 1, wherein the N-vinylpyrrolidone has a purity of not less
than 99.7 weight %.
6. A production process for a vinylpyrrolidone polymer according to
claim 2, wherein the N-vinylpyrrolidone has a purity of not less
than 99.7 weight %.
7. A production process for a vinylpyrrolidone polymer according to
claim 3, wherein the N-vinylpyrrolidone has a purity of not less
than 99.7 weight %.
8. A production process for a vinylpyrrolidone polymer according to
claim 4, wherein the N-vinylpyrrolidone has a purity of not less
than 99.7 weight %.
9. A production process for a vinylpyrrolidone polymer according to
claim 1, wherein the polymerizable monomer component or components
further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
10. A production process for a vinylpyrrolidone polymer according
to claim 2, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
11. A production process for a vinylpyrrolidone polymer according
to claim 3, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
12. A production process for a vinylpyrrolidone polymer according
to claim 4, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
13. A production process for a vinylpyrrolidone polymer according
to claim 5, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
14. A production process for a vinylpyrrolidone polymer according
to claim 6, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
15. A production process for a vinylpyrrolidone polymer according
to claim 7, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
16. A production process for a vinylpyrrolidone polymer according
to claim 8, wherein the polymerizable monomer component or
components further include a crosslinkable monomer, and wherein a
water-insoluble and/or water-swellable vinylpyrrolidone polymer is
obtained.
Description
BACKGROUND OF THE INVENTION
[0001] A. TECHNICAL FIELD
[0002] The present invention relates to a production process for a
vinylpyrrolidone polymer.
[0003] B. BACKGROUND ART
[0004] Vinylpyrrolidone polymers, such as poly(vinylpyrrolidone)
and vinylpyrrolidone copolymers, are widely used in various fields
such as medicines, cosmetics, pressure sensitive adhesives or
adhesives, paints, dispersants, inks, and electronic parts, because
the vinylpyrrolidone polymers have merits and advantages of
biocompatibility, safety, hydrophilicity, and so on. In addition,
crosslinked products of the vinylpyrrolidone polymers are useful as
water-absorbent resins for various uses requiring water absorption
and/or water retention, for example, disposable diapers.
[0005] Up to now, N-vinylpyrrolidone as used for producing the
vinylpyrrolidone polymers is, for example, industrially produced by
a process comprising the step of carrying out a reaction between
2-pyrrolidone and acetylene (Reppe process) or by a process
comprising the step of carrying out a dehydration reaction of
N-hydroxyethylpyrrolidone. In addition, both 2-pyrrolidone and
N-hydroxyethylpyrrolidone, which are precursors of the
N-vinylpyrrolidone in these production processes, are usually
derived from .gamma.-butyrolactone, and this .gamma.-butyrolactone
is known to be produced by, for example, (1) a process comprising
the step of obtaining .gamma.-butyrolactone by way of
1,4-butanediol from acetylene and formaldehyde, (2) a process
comprising the step of obtaining .gamma.-butyrolactone by way of
1,4-butanediol from butadiene and acetic acid, or (3) a process
comprising the step of carrying out a hydrogenation reaction of
maleic anhydride.
[0006] However, in many cases where N-vinylpyrrolidone as obtained
by these processes is polymerized, the molecular weight of the
resultant polymer is hard to raise, or a large amount of monomers
remain. Such disadvantages do not only reduce the purity or yield
of the resultant vinylpyrrolidone polymer, but also bring about
problems of such as use limitation or productivity deterioration.
Furthermore, for example, in the case where the resultant polymer
is crosslinked to convert it into a water-absorbent resin, the
above disadvantages are causes of the deterioration of resin
properties such as water absorption capacity and gel strength.
SUMMARY OF THE INVENTION
[0007] A. OBJECT OF THE INVENTION
[0008] An object of the present invention is to provide a
production process for a vinylpyrrolidone polymer which process
enables to obtain a vinylpyrrolidone polymer that has a desired
molecular weight and involves only a small amount of residual
monomers, wherein the vinylpyrrolidone polymer can display
excellent properties even if the vinylpyrrolidone polymer is, for
example, crosslinked to convert it into a water-absorbent
resin.
[0009] B. DISCLOSURE OF THE INVENTION
[0010] The present inventors diligently studied to solve the
above-mentioned problems. As a result, the inventors directed their
attention to a fact that 2-pyrrolidone or
N-hydroxyethylpyrrolidone, which is a raw material for synthesizing
N-vinylpyrrolidone, is usually derived from .gamma.-butyrolactone,
and then they have found that the polymerization of
N-vinylpyrrolidone is easily hindered when the
.gamma.-butyrolactone content in N-vinylpyrrolidone is more than a
certain amount. Furthermore, they have found that in the case where
acetylene is used as a raw material when obtaining
N-vinylpyrrolidone, for example, in the case where acetylene is
used when producing the .gamma.-butyrolactone which is an
intermediate raw material for N-vinylpyrrolidone or where
N-vinylpyrrolidone is produced by the reaction between
2-pyrrolidone and acetylene, by-products by nucleomethylation of
N-vinylpyrrolidone are formed and hinder the polymerization of
N-vinylpyrrolidone. The present invention has been completed on the
basis of these findings.
[0011] That is to say, a production process for a vinylpyrrolidone
polymer, according to the present invention, comprises the step of
polymerizing a polymerizable monomer component or components which
include N-vinylpyrrolidone, wherein:
[0012] (1) the N-vinylpyrrolidone as used is N-vinylpyrrolidone
having a .gamma.-butyrolactone content of not more than 500 ppm;
and/or
[0013] (2) the N-vinylpyrrolidone as used is N-vinylpyrrolidone
obtained without using acetylene as a raw material.
[0014] These and other objects and the advantages of the present
invention will be more fully apparent from the following detailed
disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Hereinafter, a detailed description is given about a mode
for carrying out the present invention.
[0016] In the present invention, firstly, it is important to use
N-vinylpyrrolidone having a .gamma.-butyrolactone content of not
more than 500 ppm. When synthesizing N-vinylpyrrolidone, there is a
case where .gamma.-butyrolactone remains in the resultant
N-vinylpyrrolidone because N-vinylpyrrolidone is usually produced
by way of .gamma.-butyrolactone. In the case where the
.gamma.-butyrolactone content in N-vinylpyrrolidone exceeds 500
ppm, the polymerization of N-vinylpyrrolidone is hindered. The
method for decreasing the .gamma.-butyrolactone content to not more
than 500 ppm is not especially limited. However, for example, in
the production process for N-vinylpyrrolidone, the
.gamma.-butyrolactone content in N-vinylpyrrolidone can be
decreased by promoting the conversion of .gamma.-butyrolactone
using an excess of ammonia relative to .gamma.-butyrolactone in the
case of producing N-vinylpyrrolidone by way of 2-pyrrolidone as a
precursor, or using an excess of ethanolamine relative to
.gamma.-butyrolactone in the case of producing N-vinylpyrrolidone
by way of N-hydroxyethylpyrrolidone as a precursor. In addition,
the .gamma.-butyrolactone content in N-vinylpyrrolidone or in
2-pyrrolidone and N-hydroxyethylpyrrolidone, which are precursors,
may be decreased by conventional purification methods such as
distillation and crystallization.
[0017] In the present invention, secondly, it is important to use
N-vinylpyrrolidone obtained without using acetylene as a raw
material, whereby not only can the formation of by-products by
nucleomethylation of N-vinylpyrrolidone, namely,
N-vinyl-3-methyl-2-pyrrolidone, N-vinyl-4-methyl-2-pyrrolidone, and
N-vinyl-5-methyl-2-pyrrolidone, be inhibited, but also the bad
influence that the polymerization of N-vinylpyrrolidone is
hindered, which bad influence is caused by the above by-products,
can be prevented. In more detail, there is a possibility that
acetylene is used in steps, such as (1) and (2) below, in the
production process for N-vinylpyrrolidone. However, it is important
to avoid using acetylene in both of:
[0018] (1) a step of a vinylation reaction of 2-pyrrolidone with
acetylene, and
[0019] (2) a step of synthesizing 1,4-butanediol from formaldehyde
and acetylene in order to obtain .gamma.-butyrolactone which is
used as a precursor of 2-pyrrolidone or N-hydroxyethylpyrrolidone
which is a raw material for synthesizing N-vinylpyrrolidone.
[0020] In the present invention, it is the most preferable to use
N-vinylpyrrolidone which has a .gamma.-butyrolactone content of not
more than 500 ppm and is obtained without using acetylene as a raw
material.
[0021] There is no especial limitation in the production process
for N-vinylpyrrolidone as used in the present invention if this
process is the above process without using acetylene. However, the
process preferably involves a gas phase dehydration reaction of
N-hydroxyethylpyrrolidone. Furthermore, it is preferable that a
product derived from maleic anhydride is used as
.gamma.-butyrolactone which is a precursor of
N-hydroxyethylpyrrolidone. The specific method for carrying out the
gas phase dehydration reaction of N-hydroxyethylpyrrolidone is not
especially limited and, for example, methods as reported in
JP-A-141402/1996 and Japanese Patent No. 2939433 can be
adopted.
[0022] The purity of the aforementioned N-vinylpyrrolidone, as used
in the present invention, is preferably not less than 99.7 weight
%. In the case where N-vinylpyrrolidone having a purity of less
than 99.7 weight % is polymerized, there are disadvantages in that
the polymerization of the N-vinylpyrrolidone might be hindered by
influence of impurities other than .gamma.-butyrolactone and the
nucleomethylated N-vinylpyrrolidone wherein the impurities have not
been identified yet.
[0023] The production process according to the present invention
comprises the step of polymerizing a polymerizable monomer
component or components which include the aforementioned
N-vinylpyrrolidone. There is no especial limitation in the
polymerizable monomer component or components if they include at
least the aforementioned N-vinylpyrrolidone. For example,
N-vinylpyrrolidone may be used either alone or in combination with
any polymerizable monomer that can be copolymerized with
N-vinylpyrrolidone. Incidentally, when the polymerizable monomer
other than N-vinylpyrrolidone is copolymerized with
N-vinylpyrrolidone, the N-vinylpyrrolidone content in the
polymerizable monomer components is not especially limited, but is
preferably not less than 50 weight %, more preferably not less than
90 weight %.
[0024] The polymerizable monomer that can be copolymerized with
N-vinylpyrrolidone is not especially limited. Specific examples
thereof include: 1) (meth)acrylate esters such as methyl
(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate,
cyclohexyl (meth)acrylate, and hydroxyethyl (meth)acrylate; 2)
(meth)acrylamide and derivatives therefrom such as
N-monomethyl(meth)acrylamide, N-monoethyl(meth)acrylami- de, and
N,N-dimethyl(meth)acrylamide; 3) basic unsaturated monomers, such
as dimethylaminoethyl (meth) acrylate, dimethylaminoethyl(meth)
acrylamide, vinylpyridine, and vinylimidazole, and their salts or
quaternized products; 4) vinylamides such as vinylformamide,
vinylacetamide, and vinyloxazolidone; 5) carboxyl-group-containing
unsaturated monomers, such as (meth)acrylic acid, itaconic acid,
maleic acid, and fumaric acid, and their salts; 6) unsaturated
anhydrides such as maleic anhydride and itaconic anhydride; 7)
vinyl esters such as vinyl acetate and vinyl propionate; 8)
vinylethylene carbonate and derivatives therefrom; 9) styrene and
derivatives therefrom; 10) 2-sulfoethyl (meth)acrylate and
derivatives therefrom; 11) vinylsulfonic acid and derivatives
therefrom; 12) vinyl ethers such as methyl vinyl ether, ethyl vinyl
ether, and butyl vinyl ether; and 13) olefins such as ethylene,
propylene, octene, and butadiene. Of these, particularly, groups 1)
to 8) are favorable in respect to, for example, the
copolymerizability with N-vinylpyrrolidone. As to the above
monomers, only one kind or any mixture of two or more kinds may be
copolymerized with N-vinylpyrrolidone.
[0025] In the present invention, particularly, a crosslinkable
monomer having at least two polymerizable double bond groups per
molecule is preferably copolymerized with N-vinylpyrrolidone. This
crosslinkable monomer may be copolymerized along with the
above-mentioned various polymerizable monomers. If a proper amount
of the crosslinkable monomer is copolymerized with
N-vinylpyrrolidone, any crosslinked structure can be formed to
obtain a water-absorbent resin having water insolubility and/or
water swellability. The water-absorbent resin is useful as
water-absorbing agents for various uses requiring water absorption
and/or water retention, for example, disposable diapers.
[0026] Specific examples of the above crosslinkable monomer include
N,N'-methylenebis(meth)acrylamide,
N,N'-methylenebis(N-vinylalkylamides), (poly)ethylene glycol
di(meth)acrylate, (poly)propylene glycol di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, trimethylolpropane
di(meth)acrylate, glycerol tri(meth)acrylate, glycerol acrylate
methacrylate, ethylene-oxide-denatured trimethylolpropane
tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,
dipentaerythritol hexa(meth)acrylate, triallyl cyanurate, triallyl
isocyanurate, triallyl phosphate, triallylamine,
poly(meth)allyloxyalkanes, div inylbenzene, divinyltoluene,
divinylxylene, divinylnaphthalene, divinyl ether, divinyl ketone,
trivinylbenzene, tolylene diisocyanate, and hexamethylene
diisocyanate. These may be used either alone respectively or in
combinations with each other.
[0027] The amount of the above crosslinkable monomer as used is not
especially limited and may fitly be adjusted according to aimed
uses. For example, if 0.0001 to 10 parts by weight (preferably 0.01
to 1 part by weight) of the crosslinkable monomer is copolymerized
with 100 parts by weight of N-vinylpyrrolidone, a crosslinked
polymer which has excellent water absorption capacity and gel
strength can be obtained.
[0028] The polymerization reaction method in the present invention
is not especially limited. For example, the polymerization reaction
can be carried out by conventional polymerization methods such as
solution polymerization, emulsion polymerization, suspension
polymerization and precipitation polymerization.
[0029] As to solvents as used in the above-mentioned polymerization
reaction, water is preferable. However, a solvent that can dissolve
in water can also be used by mixing it with water. Examples of such
a solvent include at least one alcohol selected from the group
consisting of methyl alcohol, ethyl alcohol, isopropyl alcohol,
n-butyl alcohol, and diethylene glycol. Particularly, if a mixed
solvent obtained by mixing water with a solvent such as isopropyl
alcohol or n-butyl alcohol is used, there are advantages of
inhibiting side reactions because the boiling point of water,
namely, the polymerization temperature, becomes low due to
azeotropic function.
[0030] When carrying out the above-mentioned polymerization
reaction, reaction conditions such as reaction temperature and
pressure are not especially limited. It is, for example, preferable
that the reaction temperature is in the range of 20 to 150.degree.
C. and that the pressure in the reaction system is normal or
reduced pressure.
[0031] When carrying out the above-mentioned polymerization
reaction, a polymerization initiator can be used. There is no
especial limitation in the polymerization initiator if the
initiator can generate radicals due to such as heating. However, a
water-soluble initiator that uniformly dissolves in water into a
concentration of not less than 5 weight % at room temperature is
favorable. Specific examples thereof include: peroxides such as
hydrogen peroxide and t-butyl hydropeoxide; azo compounds such as
2-(carbamoylazo)isobutyronitrile, 2,2'-azobis(2-amidinopropane)
dihydrochloride, 2,2'-azobis(2-methyl-N-phe- nylpropionam idine)
dihydrochloride, 2,2'-azobis[2-(N-allylamidino)propane- ]
dihydrochloride,
2,2'-azobis[2-(5-hydroxy-3,4,5,6-tetrahydropyrimidin-2--
yl)propane] dihydrochloride,
2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, and
2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide]- ; persulfate
salts such as potassium persulfate, ammonium persulfate, and sodium
persulfate; and redox type initiators which generates radicals by
combinations of oxidants and reductants, such as combinations of:
ascorbic acid and hydrogen peroxide; sodium sulfoxylate and t-butyl
hydroperoxide; and persulfate salts and metal salts. These may be
used either alone respectively or in combinations with each
other.
[0032] The amount of the polymerization initiator as used is not
especially limited, but is preferably in the range of 0.002 to 15
weight %, more preferably 0.01 to 5 weight %, of the polymerizable
monomer component or components.
[0033] When carrying out the aforementioned polymerization
reaction, conventional basic pH-adjusting agents can be used to
promote the polymerization reaction or to prevent hydrolysis of
N-vinylpyrrolidone. The addition of the pH-adjusting agent can be
carried out by any method. For example, the pH-adjusting agent may
be charged into the system in the initial stage of the
polymerization or added into the system successively during the
polymerization. Specific examples of the pH-adjusting agent include
ammonia, aliphatic amines, aromatic amines, sodium hydroxide, and
potassium hydroxide. Of these, ammonia is particularly favorable.
These may be used either alone respectively or in combinations with
each other. When using the pH-adjusting agent, its amount is not
especially limited, but the pH-adjusting agent is preferably used
so that the pH of the solution during the polymerization will be in
the range of 5 to 10, more preferably 7 to 9.
[0034] When carrying out the aforementioned polymerization
reaction, conventional transition metal salts can be used in order
to, for example, promote the polymerization reaction. Specific
examples of the transition metal salt include carboxylic acid salts
or chlorides of copper, iron, cobalt and nickel. These may be used
either alone respectively or in combinations with each other. When
using the transition metal salt, its amount is not especially
limited, but is preferably in the range of 0.1 to 20,000 ppb, more
preferably 1 to 5,000 ppb, in ratio by weight to the polymerizable
monomer component or components.
[0035] When carrying out the aforementioned polymerization
reaction, such as any chain transfer agent or buffering agent can
be used, if necessary, in addition to the aforementioned
polymerization initiator and, as the occasion demands, the
aforementioned pH-adjusting agent or transition metal salt.
[0036] When carrying out the aforementioned polymerization
reaction, the method for adding the aforementioned components to be
charged is not especially limited, but the addition can be carried
out by any method of such a type as batch type or continuous
type.
[0037] (Effects and Advantages of the Invention):
[0038] The production process for a vinylpyrrolidone polymer,
according to the present invention, prevents the polymerization
reaction of N-vinylpyrrolidone from being hindered by by-products
(as formed by nucleomethylation of N-vinylpyrrolidone) or
.gamma.-butyrolactone, and therefore enables to obtain a
vinylpyrrolidone polymer that has a desired molecular weight and
involves only a small amount of residual monomers, wherein the
vinylpyrrolidone polymer can display excellent properties even if
the vinylpyrrolidone polymer is, for example, crosslinked to
convert it into a water-absorbent resin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] Hereinafter, the present invention is more specifically
illustrated by the following examples of some preferred embodiments
in comparison with comparative examples not according to the
invention. However, the present invention is not limited
thereto.
[0040] N-vinylpyrrolidone and vinylpyrrolidone polymers as obtained
in the examples and the comparative examples were analyzed by the
following methods:
[0041] (K value of vinylpyrrolidone polymer): The vinylpyrrolidone
polymer was dissolved in water into a concentration of 1 weight %,
and the viscosity of the resultant solution was measured at
25.degree. C. with a capillary viscometer, and K value was
calculated from the measured viscosity and the below-mentioned
Fikentscher's equation. It can be said that the higher the K value
is, the higher the molecular weight is.
(log.eta.rel)/C=[(75K.sub.0.sup.2)/(1+1.5K.sub.0C)]+K.sub.0K=1000K.sub.0
[0042] wherein: C denotes the grams of the vinylpyrrolidone polymer
in 100 ml of solution; and
[0043] .eta.rel denotes the viscosity of the solution for the
solvent.
[0044] (Impurities composition and purity of N-vinylpyrrolidone and
amount of unreacted residual N-vinylpyrrolidone): T h e s e we r e
measured by liquid chromatography under the following
conditions:
[0045] Column: "CAPCELL PAC C18UG12" produced by Shiseido Co.,
Ltd.
[0046] Solvent: 20 mmol/L, solution comprising aqueous sodium
1-heptanesulfonate solution/methanol (volume ratio: 95/5)
[0047] Temperature: 20.degree. C.
[0048] Flow rate: 0.1 ml/min
[0049] Production Example 1 of N-vinylpyrrolidone
[0050] Crude N-vinylpyrrolidone was obtained by carrying out a gas
phase dehydration reaction of N-(2-hydroxyethyl)-2-pyrrolidone
which had been derived from maleic anhydride as a raw material.
This crude N-vinylpyrrolidone was purified by distillation in order
that the removal ratio of the initial distillate would be 20 weight
% of the original liquid of the distillation and that the yield
would be 60 weight % of the original liquid of the distillation,
thus obtaining N-vinylpyrrolidone (NVP-A1) having an impurities
composition as shown in Table 1.
[0051] Production Example 2 of N-vinylpyrrolidone
[0052] N-vinylpyrrolidone (NVP-A2) having an impurities composition
as shown in Table 1 was obtained in the same way as of Production
Example 1 except that the crude N-vinylpyrrolidone was purified by
distillation in order that the removal ratio of the initial
distillate would be 10 weight % of the original liquid of the
distillation and that the yield would be 70 weight % of the
original liquid of the distillation.
[0053] Comparative Production Example 1 of N-vinylpyrrolidone
[0054] N-vinylpyrrolidone (NVP-B) having an impurities composition
as shown in Table 1 was obtained by adding y-butyrolactone to
N-vinylpyrrolidone (NVP-A1) (obtained in Production Example 1) in a
ratio of 520 ppm thereto.
[0055] Comparative Production Example 2 of N-vinylpyrrolidone
[0056] N-vinylpyrrolidone (NVP-C) having an impurities composition
as shown in Table 1 was obtained in the same way as of Production
Example 1 except that the crude N-vinylpyrrolidone was purified by
distillation in order that the removal ratio of the initial
distillate would be 3 weight % of the original liquid of the
distillation and that the yield would be 77 weight % of the
original liquid of the distillation.
[0057] Comparative Production Example 3 of N-vinylpyrrolidone
[0058] N-vinylpyrrolidone (NVP-D) having an impurities composition
as shown in Table 1 was obtained in the same way as of Production
Example 1 except that crude N-vinylpyrrolidone was obtained by
carrying out a gas phase dehydration reaction of
N-(2-hydroxyethyl)-2-pyrrolidone which had been derived from
.gamma.-butyrolactone as a raw material which had been obtained by
the acetylene process.
[0059] Comparative Production Example 4 of N-vinylpyrrolidone
[0060] N-vinylpyrrolidone (NVP-E) having an impurities composition
as shown in Table 1 was obtained by carrying out a reaction between
2-pyrrolidone and acetylene, wherein 2-pyrrolidone had been derived
from .gamma.-butyrolactone as a raw material which had been
obtained by the acetylene process.
EXAMPLE 1
[0061] First, 270 g of water and 0.6 g of 10 ppm aqueous copper
acetate solution were charged into a flask (capacity: 500 ml) as
equipped with a stirrer, a monomer-supplying tank, a thermometer, a
condenser and a nitrogen-gas-introducing tube, and then nitrogen
gas was introduced, and the flask was heated under stirred
conditions in order to adjust the inner temperature of the flask to
100.degree. C. Next, each of 3 g of 2% aqueous ammonia solution, 21
g of N-vinylpyrrolidone (NVP-A1) (as obtained in Production Example
1), and 1 g of 4% aqueous hydrogen peroxide solution was supplied
into the flask 6 times at intervals of 5 minutes to carry out a
polymerization. The reaction mixture was stirred for 2 hours at the
same temperature as the above to complete the polymerization, thus
obtaining an aqueous poly(vinylpyrrolidone) solution. The amount of
unreacted residual N-vinylpyrrolidone in the resultant aqueous
poly(vinylpyrrolidone) solution was 2 ppm. In addition, the K value
of the resultant aqueous poly(vinylpyrrolidone) solution was
30.
EXAMPLE 2
[0062] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out a polymerization in the same way as of Example 1
except to use N-vinylpyrrolidone (NVP-A2) as obtained in Production
Example 2. The amount of unreacted residual N-vinylpyrrolidone in
the resultant aqueous poly(vinylpyrrolidone) solution was 7 ppm. In
addition, the K value of the resultant aqueous
poly(vinylpyrrolidone) solution was 29.
COMPARATIVE EXAMPLE 1
[0063] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out polymerization in the same way as of Example 1 except
to use N-vinylpyrrolidone (NVP-B) as obtained in Comparative
Production Example 1. The amount of unreacted residual
N-vinylpyrrolidone in the resultant aqueous poly(vinylpyrrolidone)
solution was 18 ppm. In addition, the K value of the resultant
aqueous poly(vinylpyrrolidone) solution was 28.
COMPARATIVE EXAMPLE 2
[0064] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out polymerization in the same way as of Example 1 except
to use N-vinylpyrrolidone (NVP-C) as obtained in Comparative
Production Example 2. The amount of unreacted residual
N-vinylpyrrolidone in the resultant aqueous poly(vinylpyrrolidone)
solution was 39 ppm. In addition, the K value of the resultant
aqueous poly(vinylpyrrolidone) solution was 27.
COMPARATIVE EXAMPLE 3
[0065] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out polymerization in the same way as of Example 1 except
to use N-vinylpyrrolidone (NVP-D) as obtained in Comparative
Production Example 3. The amount of unreacted residual
N-vinylpyrrolidone in the resultant aqueous poly(vinylpyrrolidone)
solution was 48 ppm. In addition, the K value of the resultant
aqueous poly(vinylpyrrolidone) solution was 25.
COMPARATIVE EXAMPLE 4
[0066] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out polymerization in the same way as of Example 1 except
to use N-vinylpyrrolidone (NVP-E) as obtained in Comparative
Production Example 4. The amount of unreacted residual
N-vinylpyrrolidone in the resultant aqueous poly(vinylpyrrolidone)
solution was 52 ppm. In addition, the K value of the resultant
aqueous poly(vinylpyrrolidone) solution was 25.
EXAMPLE 3
[0067] First, 320 g of water was charged into the same flask as
that used in Example 1, and then nitrogen gas was introduced, and
the flask was heated under stirred conditions in order to adjust
the inner temperature of the flask to 70.degree. C. Next, 80 g of
N-vinylpyrrolidone (NVP-A1) (as obtained in Production Example 1)
and 0.16 g of 2,2'-azobis(2-amidinopropane) dihydrochloride were
supplied into the system over a period of 30 minutes to carry out a
polymerization. After the reaction mixture was heated for 2 hours
at the same temperature as the above, the inner temperature was
raised to 100.degree. C., and then the reaction mixture was heated
for another 1 hour to complete the polymerization, thus obtaining
an aqueous poly(vinylpyrrolidone) solution. The amount of unreacted
residual N-vinylpyrrolidone in the resultant aqueous
poly(vinylpyrrolidone) solution was 82 ppm. In addition, the K
value of the resultant aqueous poly(vinylpyrrolidone) solution was
91.
COMPARATIVE EXAMPLE 5
[0068] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out polymerization in the same way as of Example 3 except
to use N-vinylpyrrolidone (NVP-C) as obtained in Comparative
Production Example 2. The amount of unreacted residual
N-vinylpyrrolidone in the resultant aqueous poly(vinylpyrrolidone)
solution was 390 ppm. In addition, the K value of the resultant
aqueous poly(vinylpyrrolidone) solution was 89.
COMPARATIVE EXAMPLE 6
[0069] An aqueous poly(vinylpyrrolidone) solution was obtained by
carrying out polymerization in the same way as of Example 3 except
to use N-vinylpyrrolidone (NVP-E) as obtained in Comparative
Production Example 4. The amount of unreacted residual
N-vinylpyrrolidone in the resultant aqueous poly(vinylpyrrolidone)
solution was 620 ppm. In addition, the K value of the resultant
aqueous poly(vinylpyrrolidone) solution was 86.
EXAMPLE 4
[0070] An aqueous monomer solution, comprising 30 parts by weight
of N-vinylpyrrolidone (NVP-A1) (as obtained in Production Example
1), 0.053 parts by weight of tetraallyloxyethane, and 70 parts by
weight of water, was prepared, and oxygen as dissolved therein was
forced out by allowing the solution to bubble with nitrogen. The
resultant aqueous monomer solution was heated to 50.degree. C.
under nitrogen atmosphere, and then 0.027 parts by weight of
2,2'-azobis(2-amidinopropane) dihydrochloride (polymerization
initiator) was added, with the result that a polymerization started
after 2 hours, and that gelation occurred after 3 hours and 30
minutes. After the gelation, the inner temperature of the system
was raised to 80.degree. C., and the reaction had been completed
after 5 hours and 30 minutes from the addition of the
polymerization initiator. The resultant hydrogel polymer was cut
into small pieces, and then dried in a hot-air dryer of 150.degree.
C. for 2 hours, and then pulverized. The pulverized product was
classified into what passed through a wire gauze of 850 .mu.m, thus
obtaining a water-absorbent poly(vinylpyrrolidone) polymer. The
resultant polymer could absorb and retain 21.8 g/g of physiological
saline (0.9% aqueous sodium chloride solution) relative to the own
weight of this polymer.
COMPARATIVE EXAMPLE 7
[0071] A polymerization reaction was carried out in the same way as
of Example 4 except to use N-vinylpyrrolidone (NVP-E) as obtained
in Comparative Production Example 4. The reaction had been
completed after 5 hours and 30 minutes from the addition of the
polymerization initiator similarly to Example 4. However, the
polymerization rate was slower than that in Example 4, and the
resultant hydrogel polymer was softer than that obtained in Example
4. This hydrogel polymer was cut, dried, pulverized, and classified
in the same way as of Example 4, thus obtaining a comparative
polymer. The resultant polymer could absorb and retain only 7.7 g/g
of physiological saline (0.9% aqueous sodium chloride solution)
relative to the own weight of this polymer.
[0072] Various details of the invention may be changed without
departing from its spirit not its scope. Furthermore, the foregoing
description of the preferred embodiments according to the present
invention is provided for the purpose of illustration only, and not
for the purpose of limiting the invention as defined by the
appended claims and their equivalents.
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