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.PéiiCEHlGtjl Aug. 7, 31952
23
3,tl<l8,53ll
hydrogen peroxide While irradiating the resultant emul
sion with ultraviolet light preferably While maintaining
‘
hilljlf‘iill‘i‘i’ir ACETATE PAENT
its temperature between about 60° C. and 75° C., there
Hisao Miyahara and i-lideo éluzumura, Kurasliilri City,
.l'apan, assignors to Kurashilri Rayon (30., Ltd, (Ulnar:
by polymerizing the emulsi?ed vinyl acetate and forming
a stabilized polyvinyl acetate latex paint. Polyvinyl ac
etate paints prepared in accordance with the process of
yams, Japan, a corporation oi‘ Japan
No Drawing. Filed Sept. 15, 1959, $61‘. No. 340,023
tClaiins priority, application lapan Sept. 20, 1958
‘7 Claims.
((ILZild-d?d)
the invention are extremely stable at temperatures as low
C. and do not manifest any tendency to sep
arate out or to undergo any noticeable precipitation upon
~
This invention relates to polyvinyl acetate paints and, 10 standing. The precipitation of the pigments from these
paints has been found to average less than 1 percent by
bilized polyvinyl acetate paint which is extremely stable
weight when the paint is stored at room temperatures
more particularly, to a process for manufacturing a sta
at low temperatures and may be stored over extended
for periods up to six months, or even more.
periods of time without danger of separating out. The
invention provides an improved method for manufac
turing a stabilized water-based polyvinyl acetate latex
paint in which the polyvinyl acetate granules and the pig
merit particles are uniformly dispersed and do not mani
As indicated previously, the rate at which the emulsi?ed
vinyl acetate polymerizes is markedly. increased when ti
tanium dioxide is employed in conjunction with hydro~
gen peroxide, particularly when the emulsion polymeri
zation system is irradiated with ultraviolet light. Table
1 summarizes the results obtained in ?ve separate tests
fest any noticeable tendency to separate out on prolonged
standing.
The use or": water-based polyvinyl acetate .atex paints
has become increasingly important in recent years, es
20 in which an aqueous emulsion of vinyl acetate was poly
merized using varying amounts of titanium dioxide and
pecially for interior painting, because of their relative
inexpensiveness and the Wide range of .attractive and
hydrogen peroxide, both in the presence of as well as in
the absence of ultraviolet light. In each of these tests,
an aqueous emulsion of 30 parts by weight of vinyl ac
stable ?nishes that can be obtained. In general, these
paints are manufactured by polymerizing an aqueous
etate, 2 parts by Weight of polyvinyl alcohol, and 1 part
by weight of a surfactant in Water (ranging from 37 to
67 parts by weight) was prepared and then mixed with
emulsion of vinyl acetate, using hydrogen peroxide or
some other chain initiator as the polymerization catalyst,
the designated amounts of hydrogen peroxide (in the
and then dispersing various pigments, extenders, plasti~
form of ‘a 30 percent aqueous solution) and titanium
cizers, or even other polymers, in the polyvinyl acetate
emulsion to produce a concentrated latex. By way of
illustration, one of the more extensively used white paints
dioxide, the polymerizations being conducted at tempera
tures ranging from 63° C. to 66° C.
TABLE I
is presently manufactured by dispersing titanium oxide
and zinc oxide in an‘ aqueous emulsion of polyvinyl ac
35
etate, using chalk as an extender.
The stability of these Water-based polyvinyl acetate
latex paints is markedly ellected by the shape and par
ticle size of the polyvinyl acetate granules dispersed
Polymeri~
Test No
throughout the emulsion, as well as on the degree of dis
TiOz
H202
(parts) (parts) (parts)
0.15
0.15
0.15
0.15
0.15
ersion of the hydrophilic gel which is generally added
during the emulsion polymerization of vinyl acetate to
stabilize the polymer system. As a general rule, poly
Water UV Ap-
67
67
57
37
37
plied
zation
Time
(minutes)
550
240
90
90
75
Polymeri‘
ration
Conver
siou
(percent)
55
61
88
90
98
vinyl acetate paints manufactured by initially polymeriz
ing an aqueous emulsion of vinyl acetate using hydrogen
Analysis of the data shown in Table 1 indicates that
peroxide as a catalyst, and then dispersing various pig in Cir the polymerization of the emulsi?ed vinyl acetate is sub
ments and extenders in resultant emulsion tend to ir
stantially completed in only 75 minutes when titanium
reversibly precipitate at temperatures of about —5° C.,
dioxide is used in the emulsion polymerization system
the precipitation of pigment particles at normal room
in conjunction with hydrogen peroxide while irradiating
temperatures frequently being far in excess of 1 percent
the emulsion with ultraviolet light. By way of con
by weight when the paint is stored over any extended 50 trast, when the polymerization was carried out using only
period of time.
hydrogen peroxide as the catalyst and in the absence of
We have now found that by using titanium dioxide
ultraviolet light, after a total of 550 minutes the poly—
in conjunction with hydrogen peroxide in the emulsion
merization conversion was only 55 percent.
polymerization system and by irradiating the resultant
Although the titanium dioxide and hydrogen peroxide
emulsion with ultraviolet light, it is possible to accelerate 55 may be employed in the emulsion polymerization system
the rate of polymerization of the eumulsi?ed vinyl ac
over a wide range of concentration, we generally prefer
etate and to obtain a higher degree of polymerization as
to use from 50 to 300 percent by weight of titanium di—
Well as a more uniformly dispersed polymer than can
oxide and from ‘0.1 to 3 percent by weight of hydrogen
be obtained by using only hydrogen peroxide as the poly
peroxide (as a 30 percent aqueous solution), based on
merization initiator. The emulsion polymerization prod 60 the weight of the vinyl acetate added to the emulsion
polymerization system. The amount of water present in
ucts formed upon irradiating an aqueous polymerizable
the polymerizable emulsion should equal from 1 to 2.5
emulsion of vinyl acetate, hydrogen peroxide, and tita
times the weight of vinyl acetate contained in the emul
nium dioxide, with ultraviolet light have ben found to be
exceptionally stable, even after prolonged storage, and
sion.
In addition, the emulsion polymerization system
may be used Without further processing as a polyvinyl 65 should contain from 0.5 to 8 percent by Weight of a
surfactant, such as the lauroyl ester of polyethylene glycol,
acetate latex paint, or they may be further ‘compounded
‘and from 3 to 8 percent by weight of a hydrophilic gel
into other water-based paints.
>Based on these discoveries, the invention provides an
improved process for manufacturing a stabilized poly
vinyl acetate paint which comprises emulsifying vinyl
acetate in an aqueous dispersion of titanium dioxide and
ling agent, preferably a polyvinyl alcohol having a degree
of polymerization in the range from 500 to 2500, all
70 percentages (except that designating the concentration of
the hydrogen peroxide solution) being based on the weight
of vinyl acetate contained in the system. Various pig
3
ments, such as copper powder or sulfur, as well as vari
ous extenders, such as chalk or lead carbonate, may also
be added to the emulsion polymerization system.
To prepare the stabilized polyvinyl acetate paints of
the invention, the titanium dioxide and any other pigments
or extenders should ?rst be dispersed in an aqueous solu
tion containing a minor amount of both a surfactant
(emulsifying agent) and a hydrophilic gelling agent, such
as polyvinyl alcohol or partially-hydrolyzed polyvinyl ace
tate, and the hydrogen peroxide then added to this aqueous
dispersion of titanium dioxide. Following the addition
of the hydrogen peroxide to the titanium dioxide disper
4%
was prepared by dispersing 15 parts by weight of titanium
dioxide and 20 parts by weight of chalk in 38 parts by
weight of Water to which 2 parts by weight of the lauroyl
ester of polyethylene glycol and 2 parts by weight of the
copolymer of vinyl acetate and maleic acid had previously
been added. The dispersion was mixed with 1.5 parts by
weight of an ‘aqueous 30 percent solution of hydrogen
peroxide and the resultant mixture was then charged to
a polymerization reactor ?tted with an e?icient agitator
and an ultraviolet light source. After the peroxide-con
taining dispersion had been warmed to a temperature of
65° C., a monomer solution consisting of 2 parts by
weight of ‘copal resin dissolved in 23 parts by weight of
sion, vinyl acetate is emulsi?ed in the dispersion while
vinyl acetate was continuously added dropwise to the
irradiating the resultant emulsion with ultraviolet light
and maintaining its temperature between 60° C. and 75° 15 reactor» while vigorously agitating the reactants. The
resultant emulsion of vinyl acetate was polymerized by
C., polymerization frequently being completed in about
irradiating it with ultraviolet light for a period of about
one hour, or even less.
2 hours while maintaining the temperature of the emul
The following examples are illustrative of the ease v
sion at 65° C. The emulsion polymerization products
with which stabilized polyvinyl acetate paints may be
manufactured in accordance with the invention:
4 Example I
20 formed excellent water-resistant ?lms upon coating a sur
face, and could be used without further processing as a
white polyvinyl acetate latex paint.
An aqueous dispersion of 22 parts by weight of titanium
We claim:
1. A process for manufacturing a stabilized polyvinyl
dioxide, 0.15 part by weight of an aqueous (30 percent)
solution of hydrogen peroxide, 1 part by weight of lau 25 acetate paint which comprises emulsifying vinyl acetate
roxypolyoxyethylene glycol, and 3 parts by weight of
polyvinyl alcohol, in 39 parts by weight of water was
in an aqueous dispersion consisting essentially of water
and titanium dioxide and hydrogen peroxide while irradi
ating the resultant emulsion with ultraviolet light, thereby
polymerizing the emulsi?ed vinyl acetate and forming a
ultraviolet light source, using vigorous agitation to form 30 stabilized polyvinyl acetate latex paint.
2. A process for manufacturing a stabilized polyvinyl
an emulsion. The temperature of the, emulsion was
acetate paint which comprises dispersing titanium dioxide
brought to 65° C. and maintained at that temperature
in an aqueous solution consisting essentially of water
while the emulsion was irradiated with ultraviolet light,
the polymerization being completed in about 11/2 hours. ' and a minor amount of both a surfactant and a hydro
The emulsion polymerization product contained only trace 35 philic gelling agent, adding hydrogen peroxide to the
aqueous dispersion of titanium dioxide and then emulsi
amounts of unreacted vinyl acetate and acetic acid.
fying vinyl acetate in said dispersion while irradiating the
A white pigment mixture containing a total of 20 parts
resultant emulsion with the ultraviolet light, thereby poly
by weight of chalk, clay and zinc oxide, 3 parts by weight
merizing the emulsi?ed Vinyl acetate and forming a sta
of polyvinyl alcohol, 5 parts by weight of dibutyl phthal
‘ ate, and 1 part by weight of lauroxypolyoxyethylene gly~ 40 bilized polyvinyl acetate latex paint.
3. A process for manufacturing a stabilized polyvinyl
col, dispersed in 21 parts by weight of water was milled
slowly added together with 35 parts by weight of vinyl
acetate to a reactor ?tted with an e?icient agitator and an
in a ball-mill for 2 hours, and was then compounded
acetate paint which comprises dispersing titanium dioxide
with 50 parts by weight of the emulsion polymerization
in an aqueous solution consisting essentially of Water and
product described above. The resultant latex was excep
a minor amount of both a surfactant and a hydrophilic
tionally stable, showing less than 1 percent precipitation
upon standing for a period of six months, and could be
used as polyvinyl acetate latex paint.
gelling agent selected from the group consisting of poly
vinyl alcohol and partially hydrolyzed polyvinyl acetate,.
adding hydrogen peroxide to the aqueous dispersion of
Example 11
titanium dioxide and then emulsifying vinyl acetatae in
said dispersion while irradiating the resultant emulsion
An aqueous-dispersion of titanium dioxide was pre 50 with the ultraviolet light and maintaining its temperature
pared by adding 15 parts by weight of titanium dioxide,
between 60° C. and 75° C, thereby polymerizing the
2 parts by weight of the lauroyl ester of polyethylene
emulsi?ed vinyl acetate and forming a stabilized poly
glycol, 3 parts by weight of polyvinyl alcohol (e.g., par
vinyl acetate latex paint.
tially saponi?ed polyvinyl acetate), 15 parts by weight
4. A process for manufacturing a stabilized polyvinyl
of chalk, and 3 parts by weight of lead carbonate to 38 55 acetate paint which comprises dispersing from 50 to 300
parts by weight of water, and then milling the mixture
percent by weight of titanium dioxide in an aqueous solu
in a ball-mill. The titanium dioxide dispersion was intro
duced into a polymerization reactor ?tted with an agitator
and an ultraviolet light source, and then warmed to a
temperature of 65° C., using vigorous agitation. After
the titanium dioxide dispersion had been warmed to that
temperature, 1.5 parts by weight of an aqueous solution
(30 percent) of hydrogen peroxide were added to the
warmed dispersion. Following the addition of the hydro
tion consisting essentially of water and from 0.5 to 8 per
cent by weight of a surfactant and from 3 to 8 percent by
weight of a polyvinyl alcohol having a degree, of polym
erization in the range from 500 to 2500, adding from
0.1 to 3 percent by weight of an aqueous 30 percent solu
tion of hydrogen peroxide to the aqueous dispersion of
titanium dioxide and then emulsifying vinyl acetate in
said dispersion while irradiating the resultant emulsion
gen peroxide, 22 parts by weight of vinyl acetate mixed 65 with ultraviolet light and maintaining its temperature be
with 2.2 parts by weight of dibutyl phthalate were con
tween 60° C. and 75° 0, thereby polymerizing the emul
tinuously added to the reactor over a period of 2 hours.
si?ed vinyl acetate and forming a stabilized polyvinyl ace
Polymerization was completed by irradiating the resultant
tate latex paint, all percentages except that designating
emulsion with ultraviolet light while maintaining its tem
the
concentration of the hydrogen peroxide solution being
70
perature at 65° C. The emulsion polymerization prod
ucts were exceptionally stable on standing, and could be
used directly as a polyvinyl acetate latex paint.
based on the weight of vinyl acetate added to the titanium
dioxide dispersion.
.
5. A process for manufacturing a stabilized polyvinyl
Example III
acetate paint which comprises dispersing from 50 to 300
An aqueous dispersion of titanium dioxide and chalk 75 percent by weight of titanium dioxide in an aqueous solu
5
tion consisting essentially of water and from 0.5 to 8 per
cent by Weight of a surfactant and from 3 to 8 percent by
weight of a polyvinyl alcohol having a degree of polym
6. A stabilized polyvinyl acetate paint prepared by the
process of claim 1.
7. A stabilized polyvinyl acetate paint prepared by the
erization in the range from 500 to 2500, adding from 0.1
process of claim 4.
to 3 percent by ‘Weight of an aqueous 39 percent solution 5
of hydrogen peroxide to the aqueous dispersion of tita
References Qitetl in the tile of this patent
nium dioxide and then emulsifying vinyl acetate and up
UNITED STATES PATENTS
to 10 percent by weight of a dialkyl phthalate plasticizer
in said dispersion while irradiating the resultant emulsion
with ultraviolet light and maintaining its temperature be
tween 60° C. and 75° (1., thereby polymerizing the ernul
si?ed vinyl acetate and forming a stabilized polyvinyl ace
tate latex paint, all percentages except that designating
the concentration of the hydrogen peroxide solution being
based on the Weight of vinyl acetate added to the tita~ 15
nium dioxide dispersion.
1,586,803
2,914,495
Herrrnann et 21 _________ __ June 1, 1926
Gordon et all ________ __ Nov. 24-, l959
FOREEGN PATENTS
388,309
Great Britain __________ __ Feb. 23, 1933
OTHER R.“FERENCES
Payne: Organic Coating Technology, vol. 1 (i954),
page 523.
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