Note: Descriptions are shown in the official language in which they were submitted.
- ~038988
This invention concerns a water-in-re~in
emulsion which can be cured, and if desired, dewatered
after curing.
Vinyl ester resins, prepared by reaction of
a polyepoxide with an ethylenically unsaturated mono-
carboxylic acid, are now known to form water-in-resin
emul~ions without the aid of an emulsifier. To as~i~t
in dewatering the cured emulsion without cracking os
splitting, it i9 ~ncwn to use certain nonionic ~urfactants
in the emulsions. It is also known to add certain
polymers which are insoluble in either phase of the
emulsion to obtain dimensional control.
~ he pre~ent invention provides a water-in-resin
emulsion which comprisesJ by weight from 20 to 80 per-
cent of a di~persed aqueous phase and from 80 to 20percent of a continuous resin phase which compri~es a
mixture of from 30 to 80 percent of a terminally un-
- saturated vinyl ester resin prepared by reaction of
- a polyepoxide with an ethylenically unsaturated mono-
carboxylic acid and from 70 to 20 percent of a co-
polymerizable aIkenylaromatic monomer, characterized
in that the emulsion contains from 0.5 to 20 percent,
preferably 5 to 15 percent, based on the weight of
the emulsion, of a dimension control agent which is
soluble in the re~in phase and which consi~t~ of a co-
polymer of a) from l to 70 percent, preferably 50 to 70
percent, of a monoal~enylaromatic monomer, b) from l to 60
percent, preferably lO to 60 percent, of an aLkyl (Cl_l2)
acrylate or methacrylate, and c) from 0 to 50 percent,
- 30 preferably lO to 50 percent of a hydroxyalkyl(C2 63
acrylate of methacrylate.
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~ ~038988
The density of the cured emulsion may range
from 15 to 50 lbs/cu. ft. (240-800 kg./m.3) if it is
dewatered and from 40 to 180 lbs/cu. ft. (640-2880
kg./m.3) if not dewatered. The densities also vary
depending on the resin components and their propor- -
tions, and whether additives such as fillers are
used.
The amount of the aqueous phase varies from
about 20 to 80 weight percent with a preferably upper
level of about 60 percent and a preferably lower level
of about 40 percent. The balance to make lO0 percent
- comprises the mixture of the vinyl ester resin and mono- ~-
mer a~ the continuous resin phase. The weight propor-
tions of re~in to monomer may vary widely, but u~ually
range from about 80:20 to 30:70, respectively and pre-
; ferably 70:30 to 50:50.
The emulsions are useful in making castings
such as wall decorations or statuary, and in the de-
;, . .
- watered ~tate have many of the characteristic~ of woodand are useful in making articles such as furniture,
building panels, or ca~inet doors. ~he cured emulsions
can be sawed, painted, nailed, stapled, or drilled.
- The emulsions are also useful as soil stabilizers and
for surfacing canals, ponds, etc. to prevent 1088 of
'r 25 liquid by seepage and the like.
The monomers employed ~or preparing the di-
mension control agent are well known and typically in-
clude styrene~ vinyltoluenes a-methylstyrene~ halo-
; genated styrenes such a~ chloro or ~romo styrene~ a}kyl
substituted styrenes such as t-~utylstyreneS hydroxyethyl,
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~038988:
hydroxypropyl, hydroxybutyl and like e~ters of acrylic
and methacrylic acia where the hydroxy group is usu-
ally a 2-hydroxy group; and alkyl esters, which in-
clude the cycloalkyl esters, of acrylic and methacrylic
S acid.
The resin soluble copolymer may be prepared
by any of the known vinyl polymerization methods, e.g.,
bulk, solution, or emulsion polymerization. Bulk
or solution method are preferred herein. ~he copoly-
mers are generally prepared by heating the monomers
together in the presence of a free radical catalyst
such as a peroxide, a persulfate, or a diazo compound.
The emulsions may be made by combining the
various components in any convenient order. usually
the copolymer along with the catalyst (and surfactant
if used) is dissolved in the resin phase followed by
combination with the water under agitation to form a
creamy emulsion. As with any emulsion, stability is
dependent on applying su~ficient shear in its prepara-
tion to form small droplets of the dispersed phase
(water, in this instance). Generally, a droplet or
particle size of 10~ or less is preferred. Howe~er,
stsble emul~ions with dispersed particle sizes up
to 20-50~ and even larger may be prepared. A variety
of mechanical agitating, stirring or homogenizing
devices are well known to the trade for the preparation
of such emulsions. ~he temperature of emulsification
~ can vary widely, but is usually between 30 and 140~F. ~-
: (1-6~C.).
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~L038988
Various other material~, such as inert fillers
(kaolin clay, silica), glass fibers, mold release agents,
- surfactants, thickening agents, or pigments, also may
be added. Desirably, accelerators or promoters, such
; 5 as dimethyl aniline, dimethyl toluidine, or metal naph-
thenates, are frequently used and should be added last ;
to the emulsion since an accelerated cure may take only
a few minutes. Small amounts of paraffin wax assist
in providing tack free surfaces by concentr~ting at
the surface and excluding air. Vinyl e~ter resins are
prepared by reacting about equivalent quantities of
an unsaturated monocarboxylic acid, such as methacrylic ~ - -
acid, with a polyepoxide resin. With methacrylic acid
; and a diglycidyl ether of bisphenol A, the vinyl ester
resin has the formula
~2 = C - CC~2C~C~2o ~ C~Ca3)2
CH3 OH
; _ _ 2 ;
Thus the vinyl ester resin is characterized
by having terminal vinyl groups as opposed to acid
or hydroxyl groups found in polyester resins.
Such resins which are her~in called vinyl
ester resins are described in U.S. Pat. ~o. 3,~67,992
where the unsaturated monocarboxylic acid i~ an a-
-hydroxyal~yl acrylate or methacrylate half e~tQr of -;
a dicarboxylic acid; in U.S. Pat. No. 3,066,112; in -
U.S. Pat. No. 3,179,623; in U.S. Pat. ~o. ~,256,226
where the molecular weight of the polyepoxide i8 in- -
3~ creased by reaction of same with a dtcarboxylic acid~
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,~038988
in U.S. Pat. No. 3,301,743; and in U.S. Pat. No.
3,377,406.
A variety of polyepoxide resins may be
used in the preparation of vinyl ester resins. Use-
ful polyepoxides include polyglycidyl ethers of poly-
hydric phenols and polyhydric alcohols, epoxy novo-
lac resins, epoxidized diolefins or fatty acid~ or
drying oils provided the polyepoxide contains more
than one oxirane group per molecule. The polyepoxide~
also include those wherein the molecular weight is
increased by reaction with a difunctional compound
such as a dicarboxylic acid.
Preferred polyepoxides are the polyglycidyl
ethers of polyhydric phenols and polyhydric alcohol~,
the epoxy novolac resins and mixtures thereof wherein
the epoxide equivalent weight m~y vary from 150 up to
2000.
Unsaturatea monocarboxylic acids u~eful in
preparing vinyl ester resins include acrylic acid,
;: 20 methacrylic acid, haloqenated acrylic or methacrylic
acid, cinnamic acid, and mixtures thereof. Al~o in- ~`
- cluded are the 2-hydroxyalkyl acrylate or methacry- ;
late half esters of dicarboxylic acids wherein the
hydroxyalkyl group prefera~ly has from two to six
carbon atoms. Typical half esters include the 2-
-hydroxyethyl acrylate half ester of maleic acid,
and the 2-hydroxypropyl methacrylate half e~ter of
phthalic acid. Either ~atUrated or unsaturated
dicarboxylic acid half e~ters may be used. Con- ~
veniently the half e~ters are prepared by reactin~ ; -
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' 1~38988
about 1 mole of a dicarboxylic acid anhydride. Further
details may be found in U.S. Pat. No. 3,367,992.
- Various catalysts may be used in the preparation
of vinyl ester resin~. Catalysts include tertiary amines
such as 2,4,6-tris(dimethylaminomethyl)phenol, onium catalysts, ;
triphenyl stibine, triphenyl phosphine, and CrO3. Usually
hydroquinone or other like polymerization inhibitor i~
added to prevent polymerization during the preparation
of the resin.
Also included within the definition of Yinyl
ester resins are those vinyl ester resins which have ~een
further reacted with a reactant such as a dicarboxylic
- acid anhydride wherein said anhydride reacts with the
hydroxyl group formed in the first step reaction of the
monocarboxylic acid with the polyepoxide resin (see prior
vinyl ester resin formula). The proportions of anhydride
may vary from 0.05 to 1.2 moles if necessary per mole of
hydroxyl group. These modified vinyl ester resins have
greatly improved corrosion resistance among other properties.
Alkenyl aromatic monomers include all the mono-
alkenyl aromatic monomers previously described and other
: like monomers. For certain purposes it may be desirable
to employ at least in part, a polyalkenyl aromatic monomer
such as divinyl benzene. ~enerally, the preferred monomer
is styrene. Up to 25 percent of the aromatic monomer may
be replaced by a hydroxyalkyl acrylate or methacrylate
monomer.
While the emulsions may be cure~ by exposing
them to ionizing radiation, more frequently it is ad-
vantageous bo add a free radical generating catalyst,
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1038988
usually to the resin pha~e before emuleification, and
heat to accelerate the cure of the emulsion~ A variety
of æuch catalysts are available including peroxides,
persulfates, and azo catalysts. Benzoyl peroxide, lauroyl
peroxide, t-butyl hydroperoxide, ~-butyl perbenzoate, methyl
ethyl ketone peroxide, potassium persulfate, and azobisiso-
butyronitrile are typical. Normal catalyst levels range
from 0.1 to 5 weight percent, and the emulsion may be cured
at temperatures up to 200F. (93C.) or even higher. More
rapid curing may be obtained by adding accelerating agents
- such as lead or cobalt naphthenate or N,N-dimethylaniline.The dewaterability of the cured emulsion may be
significantly improved by the addition of a polyethylene oxide-
-polyalkylene oxide block copolymer nonionic surface active
agent wherein the hydrophobic group has a molecular weight
of at least about 1000. Suitable surfactants include thoqe
described by I. R. Schmolka, Chapter 10, "Nonionic Sur-
factantsn, Vol. 1, edited by M. J. Schick and publi~hed
by M. Dekker, Inc., N.Y. 1967. ~hese surfactants are also
disclosed in U.S. 3,669,911.
The surfactant hydrophilic group ~i.e., the
polyethylene oxide block segment) comprises from 44 to
90 percent of the weight of the surfactant, varying from
44 to 55 we~ght percent for monoinitiated heteric block
sur$actants to 60 to 90 percent with difunctional initiated ;~
all block surfactant~. Preferred molecular weight for
the former ~urfactants ranges from 1000 to 2000 while
for the latter surfactants the preferred range is 1750
to 3250.
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Very small amount~ of the nonionic ~urfactant,
as little as 0.005 part per 100 parts of emul~ion, are
effective. Much larger amounts up to 10 parts or higher
may be used, but there is no advantage therefrom. Usually,
0.005 to 2 parts is sufficient.
Following cure of the resin emul~ion containing
the surfactant, the thermoset resin may be dehydrated
merely by standing at room temperature. ~ehydration
i~ dependent on both temperature and thickness of the
resin, for example, a 1 inch (2.5 cm.) thick resin might
take about 15 days at 75F. (24C.) to dehydrate, but only
takes 2 to 3 hours at 400F. (204C.). Temperatures up
to 450-500~. (232-260C.) may be used if desired. Even
at these elevated temperatures the thermo~et resins of
this invention can be gubstantially dehydrated without
cracking or damage to the resin. Vacuum conditions may
also be u~ed in dehydrating the thermoset re~in.
` The following examples further illu~trate the
invention. All parts and percentages are by weight unless
otherwise specified. - -
Example 1
A high mc~lecular weight polyepoxide resin
was first made by reacting 32.1 parts of diglycidyl ether
of ~7isphenol A having an epoxide equivalent weight (EEW)
of 186-192 and 4.7 parts of an aliphatic polyepoxide
having an EEW of 305-335 with 3.2 part~ of bisphenol A
in the presence of tetrabutylphogphonium acetate catalyst.
The reactant~ were heated with agitation at 150~C. for 1
hour. ~rhe temperature wag then lowered and 13.5 parts
of methacrylic acid added along with a sma~l amount of
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~038988
hydroquinone inhibitor and 2,4,6-tris(dimethylaminomethyl)-
phenol catalyst. The reactants were then heated at 115-12QC.
until the weight percent of acid, as -COOH, reached about
1.2 percent. The resin wa~ cooled to 50C. and 45 parts
of styrene monomer added. Then 0.1 part of a heteric poly-
ethylene oxide-polyalkylene oxide block copolymer nonionic
surfactant and 0.2 parts of paraffin wax were added. The
total mixture will be called Resin A hereafter.
A copolymer was prepared by polymerizing a
solution containing 70 parts styrene, 30 parts hydroxy-
- propyl acrylate (HPA), 10 parts methyl methacrylate and
: 1 part benzoyl peroxide at 140-150C. The resulting
- terpolymer was dissolved in styrene (50 percent) and cooled.
~ water-in-resin emulsion was prepared by mixing
- 15 14 Ibs. (6.3 kg.) of Resin A with 69 grams of benzoyl
peroxide, 140 grams of styrene, and 1390 grams of said
terpolymer solution. A clear liquid solution was obtained, ;~
to which 20.3 Ibs. (9.2 kg.) of water was slowly added
with agitation. A smooth, white emulsion was prepared.
The emulsion was divided into six smaller por-
tions and poured into cabinet door molds, 12 x 16 x 5/8"
(30 x 40 x 1.56 cm.). N,~-Dimethyl-p-toluidine (0.2 per-
cent) was added to accelerate the room temperature cure
; of the emul~ion. Each of the parts were demolded in about
10 minutes and placed in a 390-410F. (199-210C.) forced
draft oven for a~out 1.5 hours. After cooling, the parts
were determined to have lost 50.6-55.6 percent ~f their
weight. The linear shrin~age for each of the parts was
zero percent.
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,103898~ '
Using the same resin without the terpolymer,
the emulsion shrunk 3.44 percent when cured and dried
as above. Essentially no shrinkage was found when the
; terpolymer content of the emulsion was increased from about
- 5 4 percent, above, to 9.9 percent. (The water content was
kept constant at 55 percent.)
Example 2
A series of emulsions at a 50 percent water
content was prepared similar to Example 1. The weight
percent terpolymer was varied and the dimensional change
; after dehydration was determined.
Wt. % % Dimensional
- Terpolymer Change
; ;
A 4.6 -1.0
B 8.4 +0.3
', C 10 . O O
D 11.6 +2.0
- E 14.4 +2.3
Example 3
Tests similar to Example 2 were made except
that the emulsions were cured at 98-102F. (36.6-38.8~C.)
rather than at room temperature.
Wt. % % Dimensional
Terpolymer Change
F 7.2 -1.2
- G 8.4 -1.0
H 11.6 +0.5
I 12.6 +0.3
J 1~.4 +0.8
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Example 4
Similar results as above were obtained using a
different preparative method. The copolymer was first
- prepared in the presence of the polyepoxide resin used
to form the vinyl ester resin. The polyepoxide resin
(as in Example 1) was charged to a two-liter kettle and
heated to 130C. under agitation. A solution containing
60 percent styrene, 40 percent isobutyl acrylate, and 1
percent benzoyl peroxide was added incrementally o~er
1-2 hours and then heated to l~O~C. to deactivate the ~ -
peroxide. ;-~
After cooling to about llO~C., a stoichiometric ~ -
amount of methacrylic acid to react with the epoxide groups ~ -
was added. Reaction was continued until the acid content
had dropped to a~out 1 percent. Then about 45 percent
- styrene was added and the resin cooled. The surfactant
was then added. A clear resin containing 10 percent co-
polymer was prepared. An emul~ion was then prepared
~imilar to Example 1, cured and dehydrated with zero shrinkage.
.
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