Note: Descriptions are shown in the official language in which they were submitted.
33
1 PREPA~TION OF HIGH SOLIDS COPOLYMER LATICES WITH LOW
VISCOSITY
This invention relates to the field of copolymer
5 latices and, more particularly, to such latices having
high solids content and low viscosity and bein~ prepared
from a mixture of copolymerization monomers inclu~ing a
vinyl ester and an acrylate or methacrylate ester.
Numerous procedures for the emulsion polymerization
10 and copolymerization of various ethylenically unsaturated
monomers, vinyl esters, acrylate esters and methacrylate
esters among them, have been known for some time. In
general, a latex derived from a vinyl ester and one or
more other monomers copolymerizable therewith is prepared
15 by first charging an aqueous phase containing water, surface
active agent, buffer, catalyst or catalyst system of the
free radical type and usually a protective colloid such as
polyvinyl alcohol (P~A), to a reactor. The monomers are
thereafter charged to the reactor either as separate
20 streams with mixing occurring in the reactor or in
admixture, and either all at once or incrementally, and
following heating to polymerization temperature,
- polymerization is thereafter permitted to proceed,
aceompanied by eonstant agitation, substantially to
25 completion. The resulting latex is eooled and filtered
and can be used in many applications, e.g., as paints and
other surface coating compositions, adhesives and textile
treating agents.
3o
,.~.,
S~33
--2--
1 Emulsion pol~merization procedures featuring one
or more aspects of the aforedescribed method o~ preparing
copolymer latices are descrlbed in U.S. Patent Nos.
2,496,384; 2,520,959; 3,248,356; 3,404,114; 3,423,353;
5 3,483,171; 3,804,881; and, 4, o39,500. u . s . Patent No.
3,423,353 to Levine et al. ln particular describes latlces
obtained from vlnyl acetate and one or more other comonomers
including al~yl acrylates and methacrylates such as methyl
acrylate, ethyl acr~late~ propyl acrylate, butyl acrylate,
10 isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate,
ethyl methacrylate and n-propyl methacrylate, the latices
being said to possess higher solids contents than obtainable
using conventional emulsion polymeri2ation techni~ues, while
at the same time having reduced viscosities and lmproved
15 freeze-thaw stability. The latices are prepared in the
conventional manner and once polymerization is substantially
complete, a rel~tively large amoun~ of water-soluble
polymerization catalyst or intiator is added to the
emulsion to reducs viscosity and increase particle size.
20 Xt is speculated by patentees that this post-addition of
catalyst results in some degradat~on of th~ surface active
agen'G and the ether linkage-containing protective colloid
when used, reducing their molecular weights by an oxidative
mechanism which in~rolves rupture oî the ether linkages.
25 This oxidative degradation is thought to reduce the
effectiveness of the surface actl~e agent and protecti~e
colloid resulting in some agglomeration o~ partlcles. The
larger average particle size o~ the emulsion is believed to
be also responsible for the reduction in viscosity.
50~3
It has now been discovered that latices derived
~ro~ vinyl esters and acrylate and/or methacrylate esters
having high solids contents and low viscosity can be
5 readily and conveniently prepared as a result of the
polymerization itsel~, thus dispensing with the need ~or
~urther manipulative steps ~uch as the post-addition of
relatively large quantities of catalyst o~ U.SI Patent
No. 3,423,353 to Levine et al.
The post-addition of catalyst to latices
prepared by the process of this invention has no
significant ef~ect on the viscosities o~ the products~
demonstrating that the viscosities o~ the latices herein
are for the most part ~ixed during polymerizationr
In accordance with the present invention, high
solids9 low viscosity copolymer latices are prepared from
(a) at least one vinyl ester monomer in an amount representing
from about 50 weight percent to qbout 95 weight percent o~
total monomer chargeg and (b) at least one monomer selected
20~rom the group consisting o~ acrylate ester monomer and
methacrylate ester monomer representing the balance of the
total monomer charge; which comprises, polymerizing in a
first stage, a significant portion of the total vinyl ester
monomer, e.g., at least about 10 weight percent and pre~erably
25at least about 50 weight percent of the total vinyl ester monomer~
together with from 0 to about ~0 weight percent of the total
acrylate and/or methacrylate ester monomer in an aqueous emulsion
reaction medium containing a polymerizatlon catalyst~ and thereafte
polymerizing in a second~stage the remaining portion o~ the
30total vinyl ester monomer charge together with the remaining
amount of the acrylate and/or methacrylate ester monomer in the
reaction medium containing additional catalyst if needed, polymer-
ization be~ng continued substantially to completion. Pre~erably
03 3
--4--
1 during the first sta~e, the ratio of vinyl ester to
acrylate and/or methacrylate monomer ls greater than
about 4.5 until about 40-60% of the total monomer charge
is added and during the second addition, the ratio of
5 vlnyl ester monomer to acrylate and/or methacrylate monomer
is Iess than about 4.5 unti.l the total remaining amount of
monomers has been added to the polymerization reactor.
One or more other ethylenically unsaturated monomers co~
polymerizable with monomers (a) and (b) present in an amount
10 of up to 5 welght percent of the total monomer charge can
be added at the commencement of or during the polymerization
sequence. It may be advantageous to initially polymerize
a small amount, i.e., about 5~, o~ the total vlnyl ester
monomer in the reactor prior to commencement of the first
15 stage polymerization.
The process herein contemplates the use of known
and conventional surface active agents, buffers~ protective
colloids, catalysts, and the like, in the usual amounts,
and can be carried out ~n equipment heretofore employed for
20 emulsion polymerization.
Typically, the latices produced in accordance
with this invention will possess a solids content from
- about 60 to about 70 weight percent and even higher. The
~ viscosities of the high solids latices herein are generally
25but a fraction of the viscosities of latices prepared in-
the usual manner, l.e., by simultaneous addition of monomers,
and will usually not exceed 15,000 cp. Brookf-ield viscosity
(~VF, Spindle No. 1) at 2 rpm. Viscosities of latices of
equivalent high solids which are preared in the con~entional
30way have attained 50,000 cp. Brookfi~ld ~iscosity (RVF~
Spindle No. 5) at 2 rpm. The combination of hlgh solids
content and low vi~cosity makes the latices of this invention
especially useful for formulation as paints and other surface
coatings.
~5033
The latices prepared in accordance with the process
o~ this invention contain copolymers of at least one vinyl
ester and at least one acrylate and/or methacrylate ester.
5 Generally, when preparing these copolymers, from about 50
weight percent to about 95 wei~ht percent, and preferably
from about ~5 weight percent to about 85 weight percent,
of vinyl ester will be copolymerized with ~rom about 5
weight percent to about 50 weight percent, and preferably
10 ~rom about 15 weight percent to about 35 weight percent~
of acrylate and/or methacrylate ester based on the total
weight of the monomers present.
Among the vinyl esters which can be advantageously
used in this invention are included vinyl formate, vinyl
15 propionate, vinyl butyrate and vinyl chloroacetate. Vinyl
acetate is e~pecially preferred ~or use herein. Illustra-
tive of acrylate esters and methacrylate esters which can
be used in this invention to good effect are methyl
acrylate, ethyl acrylate, propyl acrylate, butyl acrylate,
20 isobutyl acrylate, sec-butyl acrylate, amyl acrylate,
isoamyl acrylate, hexyl acrylate, 2-ethylhexylacrylate,
octyl acrylate, 3,5,5-trimethylhexyl acrylate, decyl
: acrylate, dodecyl acrylate~ cetyl acrylate, octadecyl
acrylate, cyclohexyl acrylate, phenyl acrylate, methyl
25 methacrylate, ethyl methacrylate, n-propyl methacrylate,
n-amyl methacrylate, isoamyl methacrylate, hexyl
methacrylate, 2-ethylbutyl methacrylate, octyl
methacr~late, 3~5,5-trimethylhexyl methacrylate, decyl
methacrylate, cyclohexyl methacrylate~ norbornenyl
3 methacrylate, benzyl metnacrylate, phenyl methacrylate,and
neopentyl methacrylate. Butyl acrylate has been found to
be especially advantageous ~or use herein.
As previously stated, up to 5 weight percent of
the total weight of the monomers present can be
-6--
1 interpolymerized with one or more additional ethylenically
unsaturated monomers illustrative of which are the
followin~:
ethylene, propylene, l-butene, 2-butene, isobutylene,
- 5 l-pentene, 2-methyl~2-butene, l-hexene, 4 methyl-l~pentene,
3,3-dimethyl-1-butene, 2,4,4-trimethyl-1-pentene, 6-ethyl-
l-heYene, l-heptene, l-octene, l-decene, l-dodecene, allene,
butadiene, isoprene, chloroprene, 1,5-hexadiene, 1,2,5-
hexatriene, divinylacetylene, cyclopentadiene, dicyclo-
10 pentadieneg norbornene, norbornadiene, methylnorbornene,
cyclohexene, styreneg alphà-chlorostyrene, alphamethyl-
styrene, allylbenzene, phenylacetylene, l-phenyl-l, 3-
butadiene, vinylnaphthalene, 4-methylstyrene~ 2,4-di-
methylstyrene, 3-ethylstyrene, 2,5-diethylstyrene, 2-meth-
15 oxystyren~ 4-methoxy-3-methylstyrene~ 4-chlorcstyrene, 3~
4-dimethyl-alpha-methylstyrene, 3-bromo - 4- methyl-alpha-
methylstyrene3 2,5-dichlorostyrene, 4-fluorostyrene~ 3-
iodostyrene, 4-cyan~styrene, 4~vinylbenzoic acid, 4-acet-
oxystyrene, 4-vinyl benzyl alcohol, -3-hydroxystyrene, 1,4-
20 dihydroxystyrene, 3-nitrostyrene, 2-aminostyrene, 4-~,N-
dimethylaminostyrene, 4-phenyls+yrene, 4-chloro-1-vinyl-
naphthalene, acrylic acid, methacrylic acid, acrolein,
- methacrolein, acrylonitrile, methacrylonitrile, acrylamide,
methacrylamide, N-methyl methacrylamide, chloroacrylic
25 acid, methyl chloroacrylic acid, chloroacrylonitrile~
ethacrylonitrile, ~-phenyl acrylamide, N,N-diethylacryl-
amide, N-cyclohexyl acrylamide, vinyl chloride, vinylidene
chloride, vinylidene cyanide, vinyl fluoride, vinylidene
fluoride, trichloroethene, methyl vinyl ketone~ methyl
30 isopropenyl ~etoneg phenyl ketone, methyl alpha-chlorovinyl
ketone, ethyl vinyl ketone, divinyl ketone, hydroxymethyl
vinyl ketone, chloromethyl vinyl ketone3 allilydene dia-
cetate, methyl vinyl ether, isopropyl vinyl ether, butyl
vinyl ether, 2-ethylhexyl vinyl ether, 2-methoxyethyl
3~ vinyl ether, 2-chloroethyl vinyl ether, methoxyethoxy
3 3
-7-
1 ethyl vinyl ether, hydroxyethyl vinyl ether, aminoethyl
vinyl ether, alpha-methylvinyl methyl ether, divlnyl ether,
di~inyl e~her of ethylene glycol or diethylene glycol or
triethanolamine, cyclohexyl vinyl ether, benzyl vinyl ether,
phenethyl vinyl ether, cresyl vinyl ether, hydroxyphenyl
vinyl ether, chlorophenyl vinyl ether~ napthyl vinyl ether,
d.~le~hyl maleate, diethyl maleate, di-(2-ethylhexyl)
maleate, msle~c anhydride, dimethyl fumarate, dipropyl
fumarate, vinyl ethyl sulfide, divinyl sulfide, v~nyl
10 p-tolyl sulfide, divinyl sulfone, vinyl ethyl sulfone,
vinyl ethyl sulfoxide~ vinyl sulfonic acid, sodium vinyl
sulfonate, vinyl sulfonamide, vlnyl ben~amlde, vinyl
pyridine~ N-vinyl pyrollidone, N-vinyl carbaæole, N-
(vinyl benzyl)-pyrrolidine, N-(vlnyl benzyl)-pyrrolidine,
15 N-(vinyl benzyl~ piperidine, l-vinyl pyrene, 2-isopropenyl
furan, 2-vinyl dibenzofuran, 2-methyl-5-vlnyl pyridine,
3-isopropenyl pyridine, 2-vinyl piperidine, 2-vinyl
quinoline, 2-vinyl benzoxazole 9 4-metk~1-5-vinyl.thiazole~
vinyl thiophene, 2-isopropenyl thiophene, lndene, coumarone,
20 l-chloroethyl vinyl sulfideg ~inyl 2-ethoxye~hyl sulfide,
~inyl phenyl sulfide, vinyl 2-naphthyl sulfide, allyl
mercaptans, divinyl sulfoxide, vinyl phenyl sulfoxide,
- vinyl chlorophenyl sulfoxide, methyl vinyl sulfonate, Yinyl
~ sulfoanilide, and the like. Part or all of these optional
25 monomers c~l be charged to the reactor at the commencPment
of or during the polymerlzation sequence. In some
lnstances, these monomers may be used at a co~cen-
tration below about two weight p~rcent to avoid undue
coagulation.
The surface actlve agents contemplated by_thls
in~ention include any of the known and con~entional
surface active and emulsifying agents, principally the
5()33
--8--
1 nonionic and anionic materials, and mixtures thereof
heretofore empl3yed in the em~lsion copoly~erization of
vinyl acetate and ethylene, the nonionic surfactants being
especially preferred. Among the nonionic surface active
5 agents ~hich have been found to provide good results are
~ included the t'I~epals" (G.A.~.), the "Tweens" (Atlas
Chemical) and the "Pluronics~ ASF ~yandotte). The
"Igepals" are members of a homolo~ous series of
alkylphenoxypol~(ethyleneoxy) ethanols which can be
10 reprecented by the general formula
~ ~ _ o ~ CH2 ~ ~ 1 2 ~ ~
15 ~herein R represents an alkyl radical and n represents the
number of mols of ethylene oxide employed-~ among which are
alkylphenoxypoly(ethyleneoxy) ethanols having alkyl groups
containing from about 7 to about 18 carbon atoms,
inclusive, and having from about 4 to about 100 ethyleneoxy
20 units, such as the heptylphenoY.ypoly(ethylenoY~y) ethanols,
nonylphenoxypoly(ethyleneoxy) ethanols and dodecylphenoxy-
poly(ethyleneoxy) ethanols; the sodium or ammonium salts of
the sulfate esters of these alkylphenoxypoly~ethyleneoxy)
ethanols, alkylpoly(ethyleneoxy) ethanols3 alkylpoly-
(propyleneoxy)ethanols; octylphenoxyethoxyethyldime-
thylbenzylammonium chloride; polyethylene glycol t- -
dodecylthioether. The "Tweens" are polyoxyalkylene
derivatives of fatty acid partial esters of sorbitol
anllydride such as the polyoxyalkylene derivatives of
30 sorbitan monolaurate, sorbitan rnonopa~nitate~ sorbitan
mono~tearate~ sorbitan tristearate, sorbitan monooleate and
sorbitan trioleate. The "Pluronics" are condensates of
3~ * Trade Mark
~,
~ ~S03;~
9~
1 ethylene oxide with a hydrophobic base formed b~ condensing
propylene oxide with propylene glycol, and the like. Other
suitable nonionic surfactants which can be employed herein
are ethylene oxide derivatives of long chain fatty alcohols
5 such as octyl~ dodecyl~ lauryl or cetyl alcohol. Anionic
sur~ace active agents which can be used here~n include the
alkali metal sulfates of C12 to Cll~ alcohols such as sodium
lauryl sulfate and alkali metal salts of alkyl benzene
sulfonic acids and alkyl toluene sulfonic acids having
10 aliphatic side chains of about 10 to about 15 carbon atoms~
and the like. The surface active agent is generally
employed at from about 3~ to about 5~ and preferably, at
from a~out 3.5v~ to about 4.5%g by weight of the total
monomers present.
15A protective colloid is generally incorporated in
the aqueous emulsions of this invention.~ Such known and
conventional protective colloids as: the partially and
fully hydrolyæed polyvinyl alcohols; cellulose ethers,
e.g., hydroxymethyl cellulose, hydroxyethyl cellulose,
20 ethyl hydroxylethyl cellulose and ethoxylated starch
derivatives; the natural and synthetic gums, e.g. gum
tragacanth and gum arabic, polyacrylic acid, poly(methyl
vinyl ether/maleic anhydride) and polyvinyepyrrolidone,
-- are well suited for use herein, preferably at a level of
25 from about 0.1% to about 2% by weight of the emulsion.
Polyvinylpyrrolidone and the partially hydrolyzed polyvinyl
alcohols are especially advantageous for use in this
invention.
The catalysts used in the copolymerization reaction
30 are any of tne known and conventional free radical
polymerization catalysts heretofore used for the prepara-
tion of copolymer latices and include inorganic peroxides
such as hydrogen peroxide, sodium perchlorate and sodium
perborate, inorganic persulfates such as sodium persulfate,
35 potassi.um persulfate and ammonium persulfate and reducing
5033
--10--
lagents such as sodium hydrogen sulfite. Catalyst (includ-
ing co catalyst reducing agent, lf employed) is generally
utilized at a level of from about 0.1~ to about 1~ by
weight of total comonomers. The catalyst can be added to
5the reaction medium all at once or it can be divided into
two or more parts and added to the reactor medium with
each addition of monomer or during either or both
polymerizatlon sequences.
An alkaline buffering agent such as sodium
lObicarbonate, ammonium bicarbonate~ sodium acetate, and
the like3 may be added to the aqueous system to ma~n-tain
the pH at the desired level. The amount of buffer is
generally about 0.01 to 0.5% by weight based on the
monomers.
The method by which the monomers are charged to
the reactor is not critical. The monomers can be added
to the reaction medium as a steady stream/ drop-wise or in
periodic increments; the ~inyl ester and acrylate/methacrylate
ester can be admixed pr~or to being charged to the reactor
20or these monomers can be introduced to the reactor as
separate streams. Advantageously, the monomers are added
as a steady s~ream over periods ranging from about 1 hour
to about 5 hours and preferably, over a period of ~rom
- about 2 hours to about 3 hours.
The temperakure reaction herein can be selected at
levels which have heretofore been employed in emulsion
polymerization. For both polymerization sequences the
temperature can range from about 0C. to about lOO~C~
preferably ~rom about ambient temperature to about 80C,
30wi~h the reaction medium being constantly stirred or
otherwise agitated. The substantlal completion of poly-
merization Ls usually indicated when ~ree monomer content
&~033
--11--
1 of the latex emulsion is below about 1~ and preferably
- below about 0,5~.
In the examples which follow, ln which conventional
equ~pment was used and weight parts Qre given~ examples
5 1 to 11 are illustrative of the copolymer latices and
emulsion polymerization process of this invention while
comparative examples 1~ and.lB are given by way of
illustratin~ the prior art latices and polymerization
procedures. Components of the emulsion media employed
10 in the examples are identified as follows:
033
-12-
1 Component Source Co~,position
Triton X-~O~ Ro~ and Haas Octylphenoxy
Company polyethoxy
ethanol
Triton QS-9 Rohm and Hass Phosphate ester,
* Co~pany acid form
Tamol 850 Rohm and Hass Sodium salt of
Company polymeric
carboxylic acid
Sipon ~SY Alcolac, Inc. Sodium lauryl
ether sulfate
Mono~er X-980 Rohm and Hass Trimethylol
Company propane
tri~ethacrylate
Sodium lauryl
sullate
Butyl Carbito~ Union Carbide Diethylene
Corporation glycol
monobutyl ether
Plasticizer Cincinnati Milacron
Surfactant Chemicals~ Inc.
Natrosol*250i~R Hercules, Inc. Xydroxyethyl-
cellulose
Trycol* PO-407 Emery Industries Octyl phenol
condensed with
40 units of
ethylene oxide
CI~P Acetate Troy Chemical Preservative
Corporation preparation
: containin~ lO,
- by weight of
chloromethoxy-
propylmercuric
acetate
* Trade Mark
~,
5033
-13 -
~ Example 1
.
To a 2000 ml resin flask equipped with stirrer, reflux
condenser~ addition funnel and thermometer were Added the
~ollo~ing solutions:
(a) ~eionized water 200 parts
Polyvinylpyrrolidone2.5 parts
(b) Deionized water 220 parts
TRITON X-405 40 parts
TRTTON QS-9 12.5 parts
Sodium hydroxide to pH 10
10 followed by 40 p~rts of vinyl acetate. The re~ctor was
heated with a water bath and at 60C.,1.65 parts of
ammonium persulfate in 10 parts of water ~lere added all at
once. At 72C., the addition of 320 parts ol vinyl
acetate was started and then continued at 78-80C, o~er
15 about 65 minutes. Thereafter, a mixture of 360 parts of
vinyl acetate and 150 parts o-, butyl acrylate was added
over about 120 minutes. When all the mo~omer mixture had
been added, 002 part of ammonium persulfate ~las introduced
and the batch was given an additional 30 rninutes at 80C.
20 to completely consume the monomers. Cooled to room
temperature, the copolymer latex had a 65.2 percent solids
content and a Brookfield Viscosity (RVF, Spindle No. 2) of
- 2700 cp at 2 rpm and 800 cp at 20 rpm.
,
~ J~ 3 3
-14-
lComparative Example lA
In this example, which is illustrative of the prior
art, a sin~le stage addition of monomers was used. The
protective colloid ~as omitted in order to avoid
5unmanageable viscosity for the completed latex.
To a 2000 ml resin flask equipped as in Example 1
were added:
Deionized water450 parts
TRITON X-405 37 parts
TRITON QS-9 25 parts
Sodium hydroxideto pH 10
The solution was brought to 70C ~Jith a controlled
temperature water bath and 1.65 parts of ammonium
persulfate in 10 parts of water were added all at once,
followed by a mixture of 720 parts OL vinyl acetate and
15150 parts ol but~l acrylate monomers added over about 140
minutes. The reaction temperature rapidly rose to, and
was controlled at, 800C durin~ addition of the monomers.
Followin~ the monomer addition~ 0.3 part of ammonium
persulfate in 10 parts of water additionally was added.
20 The reaction temperature was held at 80C for another hour
and then the batch was cooled to room temperature. The
copolymer latex had S4.6 percent solids content and
Brookfield viscosity (RVF, Spindle No. 5) of 50,000 cp at
2 rpm and 12,100 cp at ~0 rpm. This viscosity was
- 25alto~ether too high for a good latex paint formulation.
5 ~ 3 3
-15-
?aratlve EY~ample lB
. . _ .
This exa~ple is also illustrative of the prior art
procedure of copolymerizing all of the monomers
simultaneously. The following recipe was prepared and
5added to a resin flask equipped as in Example 1:
g.
Vinyl acetate 71
Butyl acrylate 14~
Deionized water 470
Triton X-405 37
Triton QS-9 25
NaOH 2.5
(NH4)2S2 8 1.65 + 0.3
The surface active agents were dissolved in the
water and the solution's pH was adjusted to 11.6 with the
NaOH (dissolved in H20). The solution was charged to the
reactor, heated to 70C. At this point the first part of
the (N~4)2S208 was added and the addition of the monomer
blend comrnenced. The addltion rate was fast during the
20first 2 hours o~ polymerization (approximately 80~ of the
monomer was added during this period~. During the last
half hour the monomer addition rate was lowered (with the
- latex becoming fairly viscous~. Upon completion of the
monomer addition, the second part of the catalyst was
added (dissolved in 500 ml ~ O). Afterwards, the batch
was kept at about 800C for about 1 hour. The
polymerization temperature was 80C+1C. The resulting
latex had a good appearance but was very viscous; it did
not contain any gel but it contained nurnerous air bubbles.
30The following properties of the latex were observed:
5033
1 Solids: 5~
Brook~ield Viscosity (Spindle No. 5)
r.p.m. 2 4 10 20
readin~ 25 32.5 4O 60.5
5 factor 2000 1000 400 200
cp 50000 32500 13400 ~2100
The dra~down on a ~lass plate was clear but contained many
bubbles.
l~h.ile the latex of Example 1 is an excellent
10 candidate ~or use in paints, it is readily apparent that
the latices produced in accordance with the prior art
procedure of simultaneous copolymerization are not suitable
materials for surface coating formulations.
.
~0
3o
1 Example 2
To the resin flask reactor of Example 1 were added:
Deionized water 420.parts
TRITON X-405 40 parts
SIPON ESY 20 parts
Polyvinylpyrrolidone5 parts
Sodium acetate 3.2 parts
Vinyl acetate 40 parts
Ammonium persulfate 1.65 parts in
Water 10 parts
At 72C., the addition of 320 parts of vinyl acetate was
started, then continued at 78-SooC. over about 65 minutes.
Thereafter~ a mixture of 360 parts of vinyl acetate and
150 parts of butyl acrylate was added over about 120
15 minutes. When all the monomer mixture had been added,
0.2 part of ammonium persulfate was introduced and the
batch was held an additional 30 minutes at 80C to consume
remaining monomersO When coolad to room ~emperature9 the
copolymer latex was found to have 64.8 percent solids and
20 a ~rookfield viscosity ~RVF, Spindle No. 1) of 550 cp at
2 rpm and 280 cp at 20 rpm.
~ ~S033
1 Example 3
~ .
To the resin flask reactor of Example 1 were added:
Deionized water335 parts
TRITON X-405 50 parts
SIPON ESY 22 parts
Polyvinylpyrrolidone 5 parts
Sodium acetate3.2 parts
Vinyl acetate40 parts
After the addition at 60C. of 1.~5 parts of ammonium
10 persulfate in 10 parts of water~ 320 parts of vinyl acetate
were added over 75 minutes at 78-800C. followed by a
solution of 0.1 part of ammonium persulfate in 5 parts of
water, then a mixture ol 300 parts o~ vinyl acetate and
150 parts of butyl acrylate over 135 minutes.
To complete polymerization, 0.5 part of ammonium
persulfate W&S intermittently added over the next hour.
The laiex batch, cooled to room temperature, contained
o9.5 percent solids and had a Brookfield viscosity (RVF,
Spindle No. 2) of 1200 cp at 2 rpm and 570 cp at 20 rpm.
~ ~5~33
-19 -
1 EY.ample 4
Example 2 ~ras repeated except that 8.7 parts of
acrylic acid were included in the second mono~ner addition,
i.e.~ of vinyl acetate-but~l acr~late mixture. The latex
5 contained 65.8 percent solids and had a Brookfield
viscosit~ (R~, Spindle No.-2) of 2600 cp at 2 rprn and 900
cp at 20 rpm.
~S033
^20 -
1 EY.2m1~1e 5
, .
~ o test the perlormance ol the hi~h solids latices of
this invention, standard latex paints were prepared from
the copolymer latices of Example 1 (Part A) and Example
5 2 (Part B). Usin~ normal paint making procedures, a
plgment ~rind was prepared and then let down with latex~
water alld thickener solution to arrive at sui~able brushing
viscosities. The viscosity of the Part A paint was 77 Krebs
Units (K.U.) and that of the Part B paint was 84 Kre~as
10 Units (K.U.). Both paints were drawn down on a Leneta
contrast chart, using a ~ mil drawdown bar. The dry draw-
downs ~rere exam~ned and found to be quite satisfactory with
no latex coagulation or pigment agglomeration present.
Hiding power was considered to be entirely acceptable.
15 Brushouts were made on compressed paperboard, both one and
two coa-ts, with an overni~ht dry between coats. Application
of the two paints was accomplished without noting
difficulties of any sort. Viscosities were cnecked af~er
one month for shelf stability and found to be excellen~.
20 The Part A paint increased by only 2 K.U. and tne Part 3
paint remained the same.
~5~133
1 Example 6
-
The following were added to a resin flask as in
Example lo
gm
- 5 Vin~1 acetAte 720
Butyl acrylate 150
Deionized water 455
Triton X-405 40
Sipon ESY 20
Polyvinylpyrrolidone 5
N 2 3 3.2
(NH4)2S28 165 ~ 0.1 ~ 0.2
The surface active agents, polyvinylpyrrolidone and
bu~fer were dissolved in cold water. The solution plus
1~40 gm of vinyl acetate were charged to the reactor and
heated. At 60C., the first part of the catalyst was added
and when the reaction temperature reached 72C., the
addition of the first sta~e of monomer (320 gm vinyl
acetate) was started. During this addition (65 minutes)
20the polymerization temperature was kept between 7~-78C.
with coolinO. Immediately after completing the addition
of the ~irst stage, the addition of the second stage
- (3500m vinyl acetate admixed with 150 gm butyl acrylate)
was started. I'he reaction temperature dropped, and light
25 heating was necessary to keep the reaction temperature
from falling. The rate of addition was somewhat low in
order to prevent the build up of free monomer in the
.eactor which mi~ht otherwise produce foam~- Catalyst was
added both when the addition had started and upon its
30 co~pletion. A~ter completion of the monomer addition_
(160 minutes) the temperature rose to 84C. The latex
obtained had a good appearance. Very little ~rit remained
on the filter after the latex had been screened.
5 0
-22-
1 The follo~lirlg properties of the latex ~lere observed:
Solids: 54.8~
Brool~field Viscosity (Spindle No. 1)
rOp.m~ 2 4 10 20
5 reading li 185 35 56 .
factor 5 25 10 5
cp 55 ~2 3~ 280
Glass drawdown of the latex appeared very good; the latex
was some~hat hazy but gel/bubble-free.
5~ 33
-23-
l E~aMple 7
The following were added to a resin flask as in
Example l:
gm
Vinyl acetate 740
Butyl acrylate 157
Deionized water 455
Triton X-405 40
Triton QS-9 12.5
Polyvinylpyrrolidone 3.5
NaOH 1.2
(NHl~)2S2g 1.65
The polyvinylpyrrolidone/sur~ace active agent solution
15 was prepared and pH adjusted as in the previous examples.
First stage addition of monomer (55 minutes) consisted of
increments of 40 and 320 gm vinyl acetate. Second stage
addition (140 minutes) consisted of a mixture of 380 gm
vinyl acetate and 157gm butyl acrylate. While the second
20 stage of monomer was slightly increased to compensate for
possible losses, the solids content indicated that this
was not necessary. ~hen the addition of the ~econd stage
: was started, as usual the reaction temperature dropped.
At this point O.lgm of extra catalyst was added, but
25 without much result. The reaction temperature was then
regulated by controling the monomer flow and bath
temperature. At the beginning of the second stageg the
temperature dropped to 75C., but during the major part,
it was between 78~80C. At the end of the monomer ad~ition,
30.2gm of (I~4)2S208 was added. The tem~erature rose to
83C. No ~oam was observed. The latex contained the
usual amount of grit~ but once this grit was removed by
filtration the product had an acceptable appearance. The
following properties of the latex were observed:
~L85~3 . ,
-24-
1 Solids: 65.7~
Brookfield Vis~osity (Spindle No.2)
r.p.m. 2 4 10 20
readin~ 8 12 20 29
5 factor 200 100 40 20
cp 1~00 1200 800 580
Glass drawdown of the late~ gave a slight haze but tlle
latex l~as nevertheless of good overall appearance.
~ ~ ~ S ~ 3 3
~25-
1 Example 8
The following interior paint formulations wereprepared with the copolymer latices of Examples 6 and 7:
Pi~ment Grind (in a Cowles Dissolver)
gm
Water 516
CI`IP Acetate
Ethylene Glycol 9~
Butyl CarbitolS8
K~C03
Tamol 850 8
Plasticizer Surfactant 12
3~ Natrosol 250 MR600
T102 600
Calcined Clay240
Whitening (atomite~ 1000
Total 3145
Paint A B
Pigmeni Grind 394 394
20 Latex of Example 6 80.5
Latex of Example 7 - 80.5
Water 93 95
3~ Natrosol 250 MR 15 13
~ Klebs Units (K.U.) 84 77 t
Drawdowns of Paints A and B were made on Leneta
contrast charts using a 6 mil drawdown bar. The paints
were brushed on compressed paperboard, both one and two
coats, with an overnight dry between coats. The paperboard
panel was sealed with the diluted latex of Example 6
30 before appllcation of the paint. Both drawdowns and_
brushings were satis~actory. No coagulation of latex or
pigmerlt agglomeration occurred with either paint.
Viscosities: Paint A 84 K.U.
Paint B 79 K.U.
-26 ~ ~ ~ 5~3
1 Ex~le 9
T,~e follo~lin~ were added tc a resin flaslt as in
Example 1: grn
Vinyl acetate 7
But~l acrylate 150
Deionized water 360
Triton X-405 50
Sipon ESY 22
Polyvinylpyrrolidone 5
Na 2CCH3 32
(l~4)2S208 1.~5 ~ 0.1 ~ 10.5
~irst stage addition of mono~ner (360gm of vinyl acetate
over 75 minutes) was completed and a~ter about 130cc of
monomer mixture from the second stage addition (360g~ of
15vinyl acetate rnixed ~Jith 150gm butyl acrylate) remained to
be added, the final addition of catalyst was started
(0.5gm a~nonium sulfate in 20ccH20). The resultin~ latex
had a ~ood appearance while containing the usual amount of
grit which ~Jas readily removable by filtration or similar
20means. The following properties of the latex were observed-
Solids: 69.3 - .5
Brookfield Viscosity (Spindle ~To. 2~
r.p.rn. 2 4 10 20
reading 6 9-5 17-5 28.5
25factor 200 ~oo 40 20
cp 1200 950 700 570
Glass drawdowrl of the latex made several days after the
product ~Jas made gave a very good gel and bubble free
coating.
3~
-27-
1 EXample 10
The following were added to a resin flask as in
Example 2:
gm
Vinyl acetate 720
Butyl acrylate 150
Acrylic acid 8.7
Deioni~ed water 435
Triton X-405 40
Sipon ESY 20
Polyvinylpyrrolidone 5
NaO2CCH3 3.2
(NH4)2S28 1.55 + 0.2
The polymerization was started as in Example 6 but with
15 3O0gm of vinyl acetate being added in the first stage
(oveY 65 minutes) and 3OOsm of vinyl acetate admixed with
150gm butyl acrylate and ~.7gm acrylic acid being added
in the second stage (over 160 minutes). During the second
stage9 the addition rate and bath temperature were
?0 regulated so that reaction temlperature was always close to
the bath temperature (78-80C). No catalyst addition was
made at the start of the addition of the second stage. The
final catalyst addition was ~tarted about 5 minutes after
completion of the addition and extended over a period of
25 about 15 minutes. After completion of the monomer addition,
the reaction temperature or about 40 minutes was slightly
above or equal to the bath temperature. Approxi~ately 15
minutes after the reaction temperature ha~ ~egun to decline,
the contents of the reactor were cooled to room temperature.
30 The resulting latex had no free monomer odor and had a good,
nearly grit-free appearance. Screening of the monomer was
very easily accomplished.
5033
-28-
1 Tile followin~ properties of the latex were observed
Solids: ~5.8~
Brookfield Viscosit~ (Spindle No. 2)
rpn~ 2 4 10 20
sreading 13 19 31 45
factor 200 100 40 20
cp 2~00 1900 1240 900
Glass dra~down of the latex gave a gel and bubble
free coatin~ of very good overall appearance.
gLl~S033
-29-
1 Exa~ple 11
This example results in a latex of high
vlscosity~ pol~nerization being conducted.ln a sequence of
two stag~ but with a mixture of vinyl acetate and butyl
5 acrylate being polymerized at each stage of monomer
addition~ The ~ollowing were added to a resin flask as in
~x~le 1:
gm
Vinyl acetate 700
Butyl acrylate 150
Monomer X-980 26
Acrylic ~cid 8.7
Deionized water 450
Emersal 6400 20
Trycol P0-407 - 40
~olyvinylpyrrolidone ' 2
NaO2CCH3 4
(NH4)2S28 16
To facilitate the dissolution of the Emersa~ 6400,
20 some water was added to the surface active agent followed
by heating.
The monomer mixtures were prepared as follows:
Initial
- Stage
First Stage ~gm) ' Second Stage (gm)
25 Vinyl acetate 4 310 350
~utyl acrylate 65 85
Monomer X-980 13 ^ 13
Acrylic acid 0 4.35 4-35
First stage addition o~ monomer took place over
3 80 minutes and second stage addition of monomer was carried
out over 85 minutes. No extra catalyst was added upon
completion of the monomer additions, The resulting latex
which contained the usual small amount of grit had a good
appearance with ~ust ~ trace of dilatancy.
* Trade Mark
~ .
0 3 3
. -30-
1 The following properties o~ the latex wer~
observed:
Sol.1ds: 65.2~
Broo~fleld Viscosity (Splndle No. 3)
5 r.pOmO 2 4 10
reading 16.5 1 3 3290
~ac~or 500 250 100 50
cp 8250 5250 3000 1950
Glass drawdown o~ this latex had good appearance
10 w~th only a slight haze.
~0
