U.S. patent application number 10/329419 was filed with the patent office on 2003-05-15 for process for producing vinylamine-vinyl alcohol copolymer and use of the copolymer.
This patent application is currently assigned to MITSUBISHI CHEMICAL CORPORATION. Invention is credited to Mori, Yasuharu, Satoh, Kohichi, Ueno, Nobuhiko.
Application Number | 20030092850 10/329419 |
Document ID | / |
Family ID | 27614566 |
Filed Date | 2003-05-15 |
United States Patent
Application |
20030092850 |
Kind Code |
A1 |
Mori, Yasuharu ; et
al. |
May 15, 2003 |
Process for producing vinylamine-vinyl alcohol copolymer and use of
the copolymer
Abstract
Disclosed is a process for producing a powdered water-soluble
polymer comprising hydrolyzing a copolymer comprising an
N-vinylamide unit and a vinyl acetate unit while dispersed in water
under a basic condition and then washing the resulting powdered
water-soluble polymer with at least one washing liquid selected
from an alcohol, water at 20.degree. C. or lower, and salt
water.
Inventors: |
Mori, Yasuharu; (Kanagawa,
JP) ; Satoh, Kohichi; (Kanagawa, JP) ; Ueno,
Nobuhiko; (Kanagawa, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
MITSUBISHI CHEMICAL
CORPORATION
Tokyo
JP
|
Family ID: |
27614566 |
Appl. No.: |
10/329419 |
Filed: |
December 27, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10329419 |
Dec 27, 2002 |
|
|
|
09628325 |
Jul 28, 2000 |
|
|
|
Current U.S.
Class: |
525/330.3 ;
525/60 |
Current CPC
Class: |
C08F 8/12 20130101; C08F
218/08 20130101; C08F 226/02 20130101; C08F 8/12 20130101; C08F
218/08 20130101 |
Class at
Publication: |
525/330.3 ;
525/60 |
International
Class: |
C08F 120/10 |
Claims
What is claimed is:
1. A process for producing a powdered water-soluble polymer
comprising hydrolyzing a copolymer comprising an N-vinylamide unit
and a vinyl acetate unit while dispersed in water under a basic
condition and then washing the resulting powdered water-soluble
polymer with at least one washing liquid selected from an alcohol,
water at 20.degree. C. or lower, and salt water.
2. The process according to claim 1, wherein the hydrolysis
reaction mixture is once separated into liquid and solid, and the
resulting copolymer powder is washed with the washing liquid.
3. The process according to claim 1, wherein said N-vinylamide unit
is an N-vinylformamide unit.
4. The process according to claim 1 wherein the molar ratio of said
N-vinylamide unit to said vinyl acetate unit in said copolymer is
1:99 to 50:50.
5. The process according to claim 1, wherein the hydrolysis of the
copolymer is carried out in presence of a caustic alkali.
6. The process according to claim 1, wherein the degree of
hydrolysis of the copolymer is 20% or more.
7. The process according to claim 1, wherein said washing liquid is
a lower aliphatic alcohol.
8. The process according to claim 1, wherein the washing is carried
out until the total concentration of an acetate and a formate
by-produced by the hydrolysis in the water-soluble polymer is
reduced to 5000 ppm or less.
9. The process according to claim 1, wherein said water-soluble
polymer is precipitated from the hydrolysis reaction mixture
containing 0.5 to 50% by weight of a salt.
10. A surface coating composition for paper or a plastic film which
comprises the water-soluble polymer obtained by the process
according to claim 1.
11. A dye fixing composition for fiber which comprises the
water-soluble polymer obtained by the process according to claim
1.
12. A hair setting composition which comprises the water-soluble
polymer obtained by the process according to claim 1.
13. A hair conditioning composition which comprises the
water-soluble polymer obtained by the process according to claim 1.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a process for producing a
vinylamine-vinyl alcohol copolymer, more particularly, a process
for easily obtaining the copolymer in the form of powder, and uses
of the copolymer as a hair setting composition or a hair
conditioning composition.
BACKGROUND OF THE INVENTION
[0002] Vinylamine-vinyl alcohol copolymers are known to have
various functions. For example, JP-A-62-74902 (the term "JP-A" as
used herein means an "unexamined published Japanese patent
application") describes the function as a chemical to be used in
papermaking. U.S. Pat. No. 4,713,236 teaches application to hair
care products including shampoos. JP-A-9-87144 discloses use in a
hair conditioning composition. JP-A-9-87151 proposes use in hair
styling cosmetics.
[0003] Although N-vinylformamide, which is a starting material of
the vinylamine-vinyl alcohol copolymer, has recently come to be
available in industry, the vinylamine-vinyl alcohol copolymer
itself is not manufactured on an industrial scale for the time
being because an economical process of production has not been
established as yet.
[0004] Processes of producing the copolymer that have hitherto been
reported include a process comprising acid-hydrolysis of an
N-vinylformamide-vinyl acetate copolymer in water (see
JP-A-62-74902) and a process comprising polymerizing
N-vinylformamide and vinyl acetate in an alcohol followed by
hydrolysis (see JP-B-6-51741; the term "JP-B" as used herein means
an "examined Japanese patent publication"). The former process
yields the polymer in the form of an aqueous solution, which is
inconvenient in transportation or purification. The latter process
has an advantage of easy purification because the polymer is
obtained in the form of powder but is disadvantageous in that, for
one thing, a large quantity of an alcohol is required, which leads
to an increase of cost, and, for another, complicated production
steps are involved.
SUMMARY OF THE INVENTION
[0005] The present invention has been completed in the light of the
above-described circumstances. An object of the present invention
is to provide a vinylamine-vinyl alcohol copolymer in a powdered
form at a low cost.
[0006] As a result of extensive studies, the present inventors have
found that the vinylamine-vinyl alcohol copolymer precipitates in a
powdered form where a copolymer comprising an N-vinylamide unit and
a vinyl acetate unit as dispersed in water is hydrolyzed under a
basic condition. Where the N-vinylamide-vinyl acetate copolymer is
hydrolyzed in water in an acidic condition as in the known process,
the vinylamine unit of the hydrolysate takes the form of a salt
(e.g., a hydrochloride) so that the resulting polymer dissolves in
water. On the other hand, where the hydrolysis is conducted under a
basic condition according to the invention, the vinylamine unit
takes the form of a free amine, and the desired polymer is salted
out by the influence of hydrolysis by-produced salts such as sodium
acetate and sodium formate.
[0007] The polymer obtained by hydrolysis under a basic condition
unavoidably contains by-produced salts, such as sodium acetate and
sodium formate. Washing with water is a conceivable method for
removing these salts. However, the polymer, being water-soluble,
will be dissolved when merely washed with water, resulting in a
considerable washing loss, which eventually leads to an increase of
the polymer price.
[0008] The present inventors have continued their study to settle
the above problem of washing loss and, as a result, found a
specific means for washing the hydrolysis reaction mixture which is
obtained by hydrolyzing a copolymer comprising an N-vinylamide unit
and a vinyl acetate unit under a basic condition to remove only the
impurities without being accompanied by dissolution of the desired
polymer.
[0009] The gist of the present invention consists in a process for
producing a powdered water-soluble polymer comprising hydrolyzing a
copolymer comprising an N-vinylamide unit and a vinyl acetate unit
while dispersed in water under a basic condition and then washing
the resulting powdered water-soluble polymer with at least one
washing liquid selected from an alcohol, water at 20.degree. C. or
lower, and salt water.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The polymer which can be used in the invention as a starting
material is a copolymer mainly comprising an N-vinylamide unit and
a vinyl acetate unit. The monomer providing the N-vinylamide unit
includes N-vinylformamide and N-vinylacetamide, with
N-vinylformamide being preferred. The starting copolymer usually
comprises about 1 to 50 mol % of the N-vinylamide unit and about 50
to 99 mol % of the vinyl acetate unit.
[0011] The molar ratio of the N-vinylamide unit and the vinyl
acetate unit in the copolymer usually ranges from 1:99 to 50:50,
preferably 5:95 to 50:50. Where the N-vinylamide unit content is
too high, the hydrolyzed polymer tends to dissolve.
[0012] The starting copolymer may further comprise other arbitrary
monomer units as long as the desired characteristics of the
resulting polymer are not impaired. The content of the other
monomer units, while varying depending on the monomer, is usually
30 mol % or less based on the total monomer units.
[0013] The N-vinylamide-vinyl acetate copolymer can be prepared by
known techniques such as emulsion polymerization or suspension
polymerization in water. Emulsion polymerization is recommended for
ease in handling the resulting polymer. Polymerization is carried
out by radical polymerization preferably in the presence of an azo
initiator. The monomer concentration in the polymerization system
is usually 1 to 50% by weight, preferably 10 to 45% by weight. If
desired, assistants, such as an emulsifying agent used in emulsion
polymerization or a chain transfer agent as a molecular weight
modifier, can be used. The reaction mixture as obtained by emulsion
polymerization or suspension polymerization is a white emulsion or
a slurry, respectively.
[0014] The polymerization is followed by hydrolysis. The
polymerization reaction mixture (e.g., an emulsion or a slurry) can
be subjected to hydrolysis as such or, if desired, with the polymer
concentration in water adjusted by dilution with water or
concentration by, for example, evaporation of water. The
concentration of the polymer to be hydrolyzed is usually in the
range of 1 to 50% by weight, preferably 10 to 45% by weight. If the
polymer concentration is too low, the hydrolysate polymer may
dissolve. Too high a polymer concentration requires much power for
stirring.
[0015] The hydrolysis should be carried out under a basic
condition. The basic condition is preferably such as created in the
presence of a strong alkali, particularly a caustic alkali such as
caustic soda or caustic potash.
[0016] The alkali is usually added in an amount of 0.1 to 10
equivalents, preferably 0.5 to 5 equivalents, per equivalent of the
total monomers. It should be noted that the polymer after
hydrolysis is water-soluble. It is the salt by-produced by the
hydrolysis that causes the water-soluble polymer to precipitate.
Therefore, where the amount of the base is small, and the degree of
hydrolysis is low or where the reaction system has a low
concentration or in like situations, the salt concentration may be
so low that the polymer easily dissolves or swells, resulting in a
filtration failure. Such a case can be managed by adding a
supplementary salt to accelerate precipitation (salting-out) of the
polymer. Salts which can be added include sodium acetate, potassium
acetate, sodium formate, potassium formate, sodium chloride,
potassium chloride, sodium sulfate, potassium sulfate, calcium
chloride, sodium carbonate, and potassium carbonate. In particular,
addition of a salt of a polybasic acid, such as sulfuric acid,
phosphoric acid or carbonic acid, is effective in precipitating the
polymer. The salt concentration in the precipitation system, i.e.,
the total of the salt by-produced by the hydrolysis and the
supplementary salt added to accelerate salting-out, is usually 0.5
to 50% by weight, preferably 1 to 30% by weight. The supplementary
salt, if needed, is preferably added after completion of the
hydrolysis rather than before hydrolysis.
[0017] In order to increase the degree of hydrolysis and to prevent
the hydrolysate polymer from sedimentation in lumps, it is
preferred that the reaction mixture be stirred strongly during
hydrolysis. The hydrolysis reaction temperature is usually about 20
to 100.degree. C. While not limiting, the hydrolysis reaction time
is usually about 10 minutes to about 10 hours. The degree of
hydrolysis of the polymer is usually 10 to 100%, preferably 20 to
100%, as for both the N-vinylamide unit and the vinyl acetate unit.
It is acceptable to increase the hydrolysis degree of only the
vinyl acetate unit by, for example, temperature adjustment.
[0018] By the end of the hydrolysis, the reaction mixture has
become a slurry, which is usually cooled and separated into solid
and liquid by filtration, centrifugation, sedimentation or a like
means to collect the solid matter. Since the by-produced acetate
and formate are water-soluble, most of impurities other than those
present in the surface water on the collected solid can be removed
by the solid-liquid separation, provided that the supplementary
salt or assistants to be added in the preceding steps are selected
from water-soluble ones.
[0019] Subsequently the collected polymer is washed to remove the
impurities incorporated into the polymer. The polymer being
water-soluble, washing with water will remove the impurities but is
accompanied with a considerable loss of the polymer. In the present
invention, washing is effected with a washing liquid comprising at
least one member selected from (1) an alcohol, (2) cold water at
20.degree. C. or lower, and (3) salt water in order to remove the
impurities in the polymer with a minimized polymer loss.
[0020] In case of using an alcohol, alcohol-soluble salts can be
washed away while the polymer remains undissolved. The alcohols
which can be used suitably include lower aliphatic alcohols having
1 to 4 carbon atoms, such as ethanol, methanol, and isopropyl
alcohol. Washing with these lower alcohols easily achieves
purification, removing such salts as sodium formate by dissolution.
The merit of using an alcohol resides in the possibility that some
of the emulsifying agents that may have been used in the
polymerization can be washed away efficiently. The alcohol for
washing is usually used at a temperature of 40.degree. C. or lower,
preferably 30.degree. C. or lower. In using an alcohol as a washing
liquid, it is preferred that the salt to be supplementarily added
for salting-out in the preceding stage be selected from those
having high solubility in the alcohol.
[0021] In case of using cold water as a washing liquid,
water-soluble impurities can be washed off while virtually
suppressing dissolution loss of the polymer. Since the solubility
or the rate of dissolution of the polymer in water increases with
temperature, the temperature of the washing water should be
20.degree. C. or lower, preferably 10.degree. C. or lower, still
preferably 0 to 5.degree. C.
[0022] Where the polymer is washed with salt water, impurities
other than the salt of the salt water, such as sodium formate and
sodium acetate, can be removed. Suitable salts of salt water
include sodium chloride, potassium chloride, sodium sulfate,
potassium sulfate, and calcium chloride.
[0023] While somewhat varying depending on the kind of the salt,
the salt concentration in the salt water is usually 0.5% by weight
or more, preferably 1% by weight or more, still preferably 3% by
weight or more. The temperature of the salt water is usually
40.degree. C. or lower, preferably 30.degree. C. or lower.
[0024] The washing method using cold water or salt water is
economically advantageous because no solvent other than water is
used.
[0025] The washing liquid may be a mixture of two or more of the
alcohol, cold water (20.degree. C. or lower), and the salt water.
For example, a mixture of an alcohol and water in a mixing ratio of
1:10 to 10:1 by volume can be used at a liquid temperature of
30.degree. C. or lower, preferably 20.degree. C. or lower.
[0026] Washing can be performed by sedimentation followed by
decantation, filtration followed by washing and rinsing and the
like. The number of washing times can be decided arbitrarily.
Washing with a washing liquid of a kind (an alcohol, cold water,
salt water or a mixture thereof) or a combination of two or more
kinds can be repeated several times. Washing is usually conducted
until the total concentration of the acetate and the formate
by-produced by the hydrolysis in the polymer is reduced to 5000 ppm
or less. The by-produced acetate and formate include sodium
acetate, potassium acetate, sodium formate and potassium
formate.
[0027] The washed polymer is dried in a conventional manner, for
example, by air blowing or vacuum drying. Drying temperature is
preferably 100.degree. C. or lower, still preferably 60.degree. C.
or lower. The resulting powdered polymer, which is water-soluble,
is re-dissolved in water, preferably warm water, on use. It is
recommended to use warm water at 40 to 100.degree. C.
[0028] The water-soluble polymer produced by the above-described
process can be used as, for example, wet-end paper additives,
dry-end paper additives, a dispersant, coatings applied to paper or
a plastic film, and hair care products such as a shampoo. The
polymer exhibits the respective desired functions in these uses.
When used as a coating of a plastic film, etc., the polymer has a
sufficiently low content of impurities and undergoes no reduction
of transparency or color change. The water-soluble polymer of the
invention is particularly suited as a component of hair care
products, providing hair-setting compositions including hair
sprays, styling gels, and styling mousses; shampoo compositions;
hair conditioning compositions including hair conditioners and
treating formulae for damaged hair, and the like. Form of these
hair care products include a lotion, an emulsion, gel, foam, and
aerosol. The hair-setting compositions comprising the water-soluble
polymer of the invention have excellent and long-lasting
hair-setting performance (ability to maintain hair in a desired
style). The hair conditioning compositions comprising the
water-soluble polymer of the invention exhibit excellent moisture
retaining effects.
[0029] In addition, the water-soluble polymer of the invention can
be used as a dye fixing agent, a kind of dyeing auxiliaries. It is
especially effective on dye fixing of cotton fiber dyed with
reactive dyes. The polymer also exhibits marked effects as an ink
fixing agent which is applied to the acceptor for ink jet printing,
such as paper, films, fabric, etc. In connection with dyeing of
fiber, the polymer is also suitable as an assistant ink jet
dyeing.
[0030] The present invention will now be illustrated in greater
detail with reference to Examples, but it should be understood that
the invention is not construed as being limited thereto. Unless
otherwise noted, all the percents are by weight.
EXAMPLE 1
[0031] a) Synthesis of Polymer
[0032] In a 1 liter-volume 4-necked flask equipped with a stirrer,
an inlet for nitrogen, and a cooling tube were put 270 g of
desalted water, 6.31 g of a styrene-maleic anhydride copolymer
(average molecular weight: 2600) as a dispersion stabilizer, 0.68 g
of sodium pyrophosphate as a dispersion stabilizer, 2.6 g of
N-vinylformamide, 17.7 g of vinyl acetate, and 0.045 g of
2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, available from Wako
Pure Chemical Industries, Ltd.) as a polymerization initiator, and
the mixture was heated to 65.degree. C. while stirring. When the
reaction mixture began to get white turbid, a mixture of 23.42 g of
N-vinylformamide, 159.07 g of vinyl acetate, and 0.405 g of V-65
was added thereto dropwise over 3 hours. After stirring at
75.degree. C. for 2 hours, 0.09 g of N,N'-azobisisobutyronitrile
and 135 g of desalted water were added thereto, followed by
stirring for 3 hours. To the reaction mixture were further added
0.09 g of N,N'-azobisisobutyronitrile- , and stirring was continued
at 98.degree. C. for 1 hour to give a white paste. Liquid
chromatography revealed that the percent conversions of
N-vinylformamide and vinyl acetate were 99.6% and 99.4%,
respectively.
[0033] b) Hydrolysis
[0034] To 355 g of the white pasty polymer composition was added
1.45 g of hydroxylamine hydrochloride, followed by stirring at
60.degree. C. for 1 hour. A solution of 61.1 g of sodium hydroxide
in 122 g of water was added thereto while stirring at a high speed,
and the mixture was stirred at 75.degree. C. for 6 hours and then
at 80.degree. C. for 2 hours, whereupon the reaction mixture became
a white slurry. After cooling, the white slurry was filtered
through a glass filter to give 238.4 g of a vinylamine-vinyl
alcohol copolymer. An aliquot of the polymer was analyzed to find
that the residual acetic acid content and the residual formic acid
content were 0.11 g and 0.015 g, respectively, per gram of the
polymer. The NMR analysis revealed that both the vinyl acetate unit
and the vinylformamide unit had undergone hydrolysis to a degree of
95% or more.
[0035] c) Purification of Polymer
[0036] Fifteen grams of the resulting polymer was washed with 100 g
of ice-water at 3.degree. C. on a glass filter and dried to obtain
a powdered vinylamine-vinyl alcohol copolymer in a yield of 96%. As
a result of ion chromatography, it was found that the polymer had
an acetate ion content of 0.018 g in terms of sodium acetate and a
formate ion content of 0.015 g in terms of sodium formate per gram
of the polymer.
EXAMPLE 2
[0037] An aqueous dispersion of an vinylamine-vinyl alcohol
copolymer obtained in the same manner as in Example 1-(a) and (b)
was filtered through a glass filter and washed with 0.100 g of
methanol to give a powdered polymer in a yield of 98%. The acetate
ion content and the formate ion content of the polymer were 0.01 g
(in terms of sodium acetate) and 0.001 g (in terms of sodium
formate), respectively, per gram of the polymer. COMPARATIVE
EXAMPLE 1
[0038] An aqueous dispersion of an vinylamine-vinyl alcohol
copolymer obtained in the same manner as in Example 1-(a) and (b)
was filtered through a glass filter. The polymer on the glass
filter was washed with 100 g of water at 40.degree. C., whereupon
the polymer swelled to make filtration difficult. The washed filter
cake was dried to give a lumpy vinylamine-vinyl alcohol copolymer.
The yield was 88%.
EXAMPLE 3
[0039] Use as Dye Fixing Agent, Fastness Test to Washing:
[0040] A 4 g/liter aqueous solution of the polymer obtained in
Example 1 was prepared. Silk fabric dyed with a 1.0% reactive dye
solution having the following formulation in a continuous manner
was dipped in the aqueous polymer solution, passed through a mangle
(pick-up after mangling: 70%), and heat treated at 150.degree. C.
for 90 seconds. The continuous dyeing of the silk fabric was
carried out under the following conditions.
[0041] Dye Formulation (g/liter):
1 Reactive dye (Kayacion Red P-4BN and Kayacion Turquoise 100 P-NGF
(both available from Nippon Kayaku Co., Ltd.)) Sodium alginate 0.5
Urea 100 Anhydrous sodium carbonate 15 Sodium nitrobenzenesulfonate
5
[0042] Continuous Dyeing Conditions:
[0043] (1) Padding
[0044] (2) Drying (105.degree. C..times.3 minutes)
[0045] (3) Baking (160.degree. C..times.2 minutes)
[0046] (4) Soaping (90.degree. C..times.5 minutes)
[0047] The color fastness to washing of the treated dyed fabric was
tested according to JIS L-0844. That is, a piece of the dip-dyed
fabric was sewn together with white cotton or silk cloth, put in a
5 g/liter soap solution at 70.degree. C., and agitated for 10
minutes. The degree of staining of the white cotton or silk cloth
after the test was rated on a 5 to 1 scale (5, 4-5, 4, 3-4, 3, 2-3,
2, 1-2, and 1) with a grey scale for assessing change in color
fastness test. The higher the rate, the less the color change and
fading. The results of evaluation are shown in Table 1 below.
[0048] It is seen from Table 1 that the dyed fabric treated with
the polymer of the invention exhibits markedly improved color
fastness to washing as compared with the untreated dyed fabric.
2 TABLE 1 Kayacion Red P-4BN Kayacion Turquoise P-NGF White cloth
cotton silk cotton silk Untreated 1-2 1-2 1 1 dyed fabric Treated 4
3 4 3 Fabric
EXAMPLE 4
[0049] Inkjet Paper Coatings:
[0050] Silica gel (available from Tokuyama; average secondary
particle size: 2.5 to 2.9 .mu.m) and the polymer obtained in
Example 1 which had been neutralized with 35% of hydrochloric acid
were mixed at a ratio of 10:4 by weight, and the solids content was
adjusted to 10%. The resulting coating composition was applied to
paper for plain paper copiers (available from Fuji Xerox Co., Ltd.)
with a bar coater (bar: #24) to a dry thickness of about 1 .mu.m.
The coated paper was allowed to stand in a thermostat at 23.degree.
C. and 50% RH overnight, printed on an ink jet printer EPSON
PM-750C, and tested as follows. The results obtained are shown in
Table 2 below.
[0051] 1) Water Resistance Test
[0052] The printed paper was soaked in tap water for 1 minute,
drained for 1 minute, and dried at 100.degree. C. for 5 minutes.
The ink retention of the printed area was observed with the naked
eye to evaluate the water resistance according to the following
rating criteria.
[0053] Rating Criteria for Water Resistance:
[0054] A . . . No blurring nor running of ink was observed.
[0055] B . . . Slight blurring or running of ink was observed but
acceptable for practical use.
[0056] C . . . Blurring or running of ink was observed.
[0057] D . . . The ink completely ran off (the same level as with
plain paper).
[0058] 2) Light Fastness Test
[0059] Paper having 2-cm squares printed solid in black, cyan,
magenta or yellow was exposed to light in a xenon fadeometer
supplied by Suga Shikenki at a black panel temperature of
63.degree. C. for 120 hours, and the color change was observed with
the naked eye and rated as follows.
[0060] Good . . . No color change was observed.
[0061] Poor . . . Color change was perceived with the naked
eye.
3 TABLE 2 Coated Paper Uncoated Paper Water Resistance A C Light
fastness: Black good good Cyan good good Magenta poor poor Yellow
good good
[0062] It has now been proved that the polymer of the invention,
applied onto the surface of paper, does not cause color change or
fading of ink.
EXAMPLE 5
[0063] Application to Plastic Film:
[0064] The polymer of Example 1 was dissolved in water to make a
10% aqueous solution and converted to its hydrochloride by addition
of the same amount of hydrochloric acid. The resulting resin
solution was applied to a polyethylene terephthalate (PET) film
(surface resistivity: 5.times.10.sup.13 .OMEGA./square) with a bar
coater to a dry thickness of about 1 .mu.m and dried. The dried
coating film was transparent with no precipitate of a salt,
etc.
[0065] The coated PET film was allowed to stand in a thermostat at
23.degree. C. and 50% RH for one day. The surface resistivity of
the coated film was 2.times.10.sup.7 .OMEGA./square, showing
improvement on antistatic properties.
[0066] When printed on an ink jet printer, the coated PET film had
satisfactory printability, whereas the printed image on the
uncoated PET film showed no ink fixing properties and easily rubbed
out.
EXAMPLE 6
[0067] a) Synthesis of Polymer
[0068] In a 2 liter-volume 4-necked flask equipped with a stirrer,
an inlet for nitrogen, and a cooling tube were put 642 g of
desalted water, 4.48 g of lauryldimethylaminoacetic acid betain
(ANHITOL 20BS, a surface active agent available from Kao Corp.) as
a dispersion stabilizer, 4.48 g of polyethylene glycol (molecular
weight: 20000) as a dispersion stabilizer, 1.48 g of sodium
pyrophosphate as a dispersion stabilizer, 6.3 g of
N-vinylformamide, 39.4 g of vinyl acetate, and 0.098 g of
2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, available from Wako
Pure Chemical Industries, Ltd.) as a polymerization initiator, and
the mixture was heated to 65.degree. C. while stirring. When the
reaction mixture began to get white turbid, a mixture of 56.4 g of
N-vinylformamide and 355.5 g of vinyl acetate and 0.88 g of a 5%
alcohol solution of V-65 were added thereto dropwise over 3 hours.
After stirring at 75.degree. C. for 2 hours, 4 g of a 5% methanolic
solution of N,N'-azobisisobutyronitrile and 270 g of desalted water
were added thereto, followed by stirring for 3 hours. To the
reaction mixture was further added 4 g of a 5% methanolic solution
of N,N'-azobisisobutyronitrile, followed by stirring at 98.degree.
C. for 1 hour to give a white paste. The percent conversions of
N-vinylformamide and vinyl acetate were 99.6% and 99.4%,
respectively, as measured by liquid chromatography.
[0069] b) Hydrolysis
[0070] To 1050 g of the white pasty polymer composition was added
16.45 g of a 30% aqueous solution of hydroxylamine sulfate,
followed by stirring at 60.degree. C. for 2 hours. To the mixture
was added 367.4 g of a 48% aqueous solution of caustic soda at
20.degree. C. over a period of 1 hour while stirring at a high
speed, and the mixture was stirred at 75.degree. C. for 6 hours and
then at 80.degree. C. for 2 hours, whereupon the reaction mixture
became a white slurry. After cooling, the white slurry was filtered
through a glass filter to give a crude vinylamine-vinyl alcohol
copolymer.
[0071] c) Purification of Polymer
[0072] The resulting crude copolymer was washed with 1800 g of
methanol on the glass filter and dried to obtain 223 g (yield: 93%)
a white powdered polymer. The NMR analysis revealed that both the
vinyl acetate unit and the vinylformamide unit had undergone
hydrolysis to a degree of 95% or more. The cation equivalent of the
polymer was 3.47 meq/g as obtained by colloidal titration. The
viscosity of a 4% aqueous solution of the polymer was 30.6 mPa.s.
The ion chromatographic analysis showed that the polymer had a
residual acetate ion content of 0.2% in terms of sodium acetate,
with no formate ion detected.
EXAMPLE 7
[0073] Use as Hair-Setting Composition:
[0074] A 1% aqueous solution of the polymer prepared in Example 6
was adjusted to pH 7 with lactic acid and diluted with water to
0.5%. Human hairs weighing 1.3 g were dipped in the aqueous polymer
solution to adhere 0.4 g of the polymer solution to the hair and
dried. After conditioning at 60% RH overnight, the individual
treated hair was placed on a 65 mm wide mount, and a bending
strength was measured with a load put on the center. While the hair
before the treatment had no shape retention, the treated hairs had
a maximum bending strength of 159 g, proving that the polymer of
Example 6 had hair-setting properties. Even after the treated hairs
were rubbed together, the maximum bending strength was 98 g,
showing that the setting properties remained.
[0075] The process according to the present invention provides a
copolymer comprising an N-vinylamine unit and a vinyl alcohol unit
in the form of powder at a low cost, offering a great industrial
advantage. The water-soluble polymer obtained by the process is
suitable as a component of hair-setting compositions and hair
conditioning compositions. It also finds effective use as a dye
fixing agent to be applied to fiber, etc. and a surface coating
agent to be applied to paper or plastic films.
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