Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
:,
1. Field of the Invention:: This invention relates to ` ~:
polymerizable unsaturated polyester resin syrup compositions~
to methods o~ curing such polymerizable unsaturated polyester
resin syrup composltions in an alkaline admixture with
significant quantities of aqueous alkali metal silicate,
preferably sodium silicate, and~to the thermoset products -
obtained thereby
: 2. Description of the~Prior Art: Unsaturated polyester
resin syrups are employed ~in the production of coatings,
molded, cast~and hand-lay-up products such as flat and pro-
filed bullding sheets~, automobile fenders and other shaped ~ :
components, fllrniture, plumbing fixtures, duct work, boats,
: . . .
- electrlaal component housings, electrical circuit boards, and ~ -;
.; the like. The unsaturated polyester resin syrups are ~re~
quently reinforced with fibrous fillers, customarily glass
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fibers and may be extended with inert particulate fillers
such as wood flour, silica, glass beads, clay, calcium
. carbonate and the like. See Polyesters.and Their Applica-
tions, Bjorksten et al, ~einhold Publishing Corporation, New
York 1960 (4th printing)4
Unsaturated polyester resin syrups also have been ex-
tended by dispersing water in the resin in the form of small
droplets to create a water-in-resin emulsion. Such emulsions
have been described as containing 40 to 85 percent by weight ~
water in combination with 15 to 60 percent by weight of -
unsaturated polyester syrups. See U.S. patent 3,591,191. ~:
Compositions containing 50 to 80 percent by weight of water
in a mixture of water and unsaturated polyester resin syrup
are described in U.S. patent 3,687,883. The addition of
small quantities of sodium silicate to the water phase of the
. ;.. ,.-: .
water-in-resin emulsions has been described, See German
Oenlegungsschrift 1,962,393.
~ ~ Unsaturated polyester resin syrups have been combined
..
~- with solid sodium silicate and with liquid sodium silicate
, . . , . :
and thereafter reacted with dolomite, U.S. patent 3,392,127 :.~ :
:. and its counterparts British patents 925,625 and 960,9.61 and
.
France patents 1,195,743 and addition patent 81,527. This :. ~.
'' ' ' '
source of technology asserts that li~uid sodium sillcate cannot
be mixed with more than 0.3 times it:s weight of unsaturated
polyest r resin syrup p_ior to addition of dol~mite.
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Unsaturated polyester resin syrup has been combined with
aqueous sodium silicate in a non~alkaline mixture to produce
microporous articles. See U.S. patent 2~505!353.
Small quantities of silica aerogel have been employed
as thickeners for unsaturated polyester resins, U.S. patent
2,610,959.
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~SUM~RY OF THE INVENTION
The present compositions combine as an alkaline mixture
(a) an unsaturated polyester resin syrup and (b) aqueous
alkali metal silicate, preferably sodium silicate. The
j present compositions do not appear to be emulsions, but
instead appear to blend into useful mixtures wherein the
~ identity of the~aqueous alkali metal silicate is significantly
; altered. The identity of the unsaturated polyester resin ~-
15 ~ ingredlent of`the unsaturated polyester resin syrup also is
altered. In thls sense the present compositIons and products
;are unlike the water extended polyester resins of the prior
art.
In the absence of a catalyst, the ansaturated polyester
- xesin and aqueous sodium silicate are individually water white
to amber clear liguids.~ On mixing, the mixture develops~ a
clouùy white appearance and resembles immediately a partially
gelled sodium silicate. The viscosity of the mixture in-
creases rapidly until the mixture resembles a doughy paste
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having the consistency of potter's clay.
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~n accordance with a broad aspect of the invention,
there is provided a polymerizable composition consisting
essentially of the alkaline reaction product of (a) one part by
weight of unsaturated polyester resin syrup: and (b) 0.3 to 10
parts by weight of aqueous alkali metal silicate, said compo- -
sition including a pol~merization initiator for unsaturated
polyester resin syrup. ~ :~
In accordance with another broad aspect of the
invention, there is provided a method of preparing a cured
thermoset article which comprises
- (A) mixing together under reactive conditions as an
al~aline mixture
(~) component 1 comprising one part by weight of -~
an unsaturated polyester resin syrup; and
(2) component 2 comprising 0.3 to 10 parts by ~:
weight of an aqueous alkali metal silicate;
the sa.id alkaline mixture including a polymerization
initiator for unsaturated polyester resin syrup: :
(B) shaping the said alkaline mixture into a mass having
the shape of the desired article, and
; ~C) curing the said mass. : :
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The aqueous alkali metal silicate is provided in quan-
tities ranging from O.l to lO parts by weight, preferably
o . 3 to ~ parts by weight, for each part by weight of un-
' saturated polyester resin syrup. In the present specification,
the expression unsaturated polyester resin syrup is employed
; to identify what is well known in the art as the combination
of an unsaturated polyester resin and a copolymerizable ~ -
monomer. The preferred aqueous alkali metal silicate con
tains from about 45 to about 85 parts by weight of water
and about 55 to 15 parts by weight of alkali metal silicate
solids having a weight ratio of SiO2/Na2O from 1.5 to 3.75.
Suitable initiating catalysts for the polymerization of un- ;~
saturated polyester resin syrups are included in the composi-
tion. These are normally peroxy compounds. Suitable accel-
~ 15 erators for tha initiators may be included. The initiator
; may be added to the unsaturated polyes-ter resin syrup or to
,~ the aqueous alkali metal silicate. The accelerator, if
employed, preferably is added to that liquid component which
does not contain the initiator.
Where fillers are employed they may be added to either
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of the liquid components or to both of the liquid components.
In general the amount of filler may be from O.Ol to 5.0
parts by weight for each part by weight of the mixture of
resin syrup and aqueous sodium silicate. Preferab1y where
the fillers are inert bulking agents such as finely divided
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perlite or expanded vermiculite, t~ley are not employed until
after the two liquids have been mixed. The inert bulking
agents are employed in amounts from O.l to 10 weight percent
of the composition.
A preferred active filler is aluminum oxide trihydrate -~ -
~12O3-3~I2O, also known as hydrated alumina. This material
; may be incorporated into either or both of the liquid com-
ponents in quantities up to about 1.5 times the weight of the
unsaturated polyester resin syrup and up to about 3 times the ~;
weight of the aqueous alkali metal silicate. Thus the amount
of aluminum oxide trihydrate should be less than the sum of
':
1.5 times the weight of resin syrup plus 3.0 times the weight
; of aqueous alkali metal silicate. Preferably the aluminum
oxide trihydrate is pulverized to a fineness approximating
` 15 minus-325 mesh U.S. standard screen.
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~ The inclusion of aluminum oxide trihydrate in the present
compositions increases the physical strength of the cured
compositions, e.g. hardness and abrasion resistance.
,.. ....
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~ Where reinforcing fibrous fillers are employed, glass
fibers are preferred, specifically the glass fibers which
are useful in reinforcing plastic sheets, i.e., randomly
.
oriented fibers of the type employed in glass ~iber reinforced
plastic laminates. The glass fibers may be employed as a
,
-~ ~ deposited ma~ of fibers, as a preformed glass iber mat or
ma~ be in the form of continuous filaments or woven fabrics.
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In general the weight of glass fibers is from about 10 to
200 per cent of unsaturated polyester resin syrup in the
final polyme~izable composition.
~he present materials have excellent processing char-
acteristics. Within minutes after forming, the resulting
shapes have sufficient strength to be handled and put to use.
The materials more importantly have a low smoke generating
potential when burned.
Unsaturated polyester resins are customarily fabricated
from polyesterification of polycarboxylic acids or polycar-
boxylic acid anhydrides and polyols, customarily glycols.
One of the ingredients in the polyester contains ethylenic
unsaturation, customarily the polycarboxylic acid. Typically
unsa~urated polyester resins are fabricated from dicarboxylic
1 ~ - , .
, 15 acids such as phthalic acid, phthalic anhydride, adipic acid, -~
succinic acid, tetrahydrophthalic acid or anhydride, tetra-
bromo phthalic acid or anhydride, maleic acid or anhydride,
famaric~acld. Typlcal glycols include ethylene glycol, pro-
; pylene glycol, butylene glycol,~ neopentyl glycol, diethylene
gIycol, dipropylene glycol, poly~ethylene glycol, polypropylene
'~ ~ glycol. Occasionally~trihydric and higher polyols are included
~ n the polyester such as trimethylol ethane, trimethylol pro-
, : .
,~ ~ pane, penta erythritol. Customarily a sLight stoichiometric
, ,
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excess of gIycol is employed in preparing the unsa urated
; 25 ~ polyester.
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Unsaturated polyester resin syrups are prepared when
the unsaturated polyester resin is combined with copolymer-
izable monomers which contain terminal vinyl groups. Such
monomers include styrene, alpha-methyl styrene, o-chloro-
styrene, vinyl toluene, acrylic acid, methacrylic acid, alkyl
; acrylates, alkyl methacrylates, divinyl benzene, diacrylates,
dimethacrylates, triacrylates, trimethacrylates and the like.
Customarily the copolymerizable monomer is provided in an
amount to constitute from about 10 to 40 weight per cent of
the unsaturated polyester resin syrup, i.e., the unsaturated
.
polyester resin comprises about 90 to 60 weight per cent of
. . .
the resin syrup.
A desirable modifying copolymerizable monomer is a
reaction product of polyepoxide with acrylic or methacrylic
15 ~ acid. Such products are described in U.S. patents 3,373,075,
: . .
3,301,743. Similar products can be prepared by combining a
polyol such as bisphenol-A wlth glycidyl acrylate or glycidyl
methacrylate. Such modifying copolymerizable monomers can ~ -
be employed as a partial replacement for other copolymerizable
monomers or as a partial replacement for a portion of the
unsaturated polyester resin of the resin syrup.
,: : :
~ Aqueous sodium silicate is commercially available as a
., ~ . . . . .
liquid containing 45 to 85 per cent by weight water and the
~alance~sodium silicate. The weight ratio of SiO2/Na20 is
~25 from about 1.5 to about 3.75 in the commercially available
materials.
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Aqueous potassium silicate is commercially available
as liquids containing 54 to 71 per cent by weight water and
the balance potassium silicate. The potassium silicate has
a weight ratio of Sio2/K~o from about 1080 to 2.50. Aqueous
lithium silicate is commercially availabie with weight ratios
of Sio2/Li2o of 2.50.
Typical initiators for unsaturated polyester resin syrups
include peroxy materials such as benzoyl peroxide, cumene
hydroperoxideL tertiary butyl peroxide and the like, A
particularly useful peroxy initiator for room temperature
curing is 2,5-dimethyl hexane-2,5-dimethyl-diper-2-ethyl
hexoate, The peroxy initiators customarily are provided in
the form of pastes in which the paroxy material is dispersed
in a glycol, Accelerators for the peroxy initiators include
cobalt naphthenate and cobalt octoate, ~or example.
, The mixing of the liquid unsaturated polyester resin
syrup and~the aqueous alkali metal silicate may occur in
several ways. The materials may be dumped into a common con- -
tainer and stirred, The two liquid materials may be sprayed
20~ separately with the sprays of the two materials impinging upon~
-~ ~ one another to provide a combined spray in which the spray
`~ ~ particles are homogeneously admixed. The two liquids may be
introduced into spraying equipment which has a common mixing
chamber preceding the spray nozzle, In most instances the
: , . ,
two liquids, when combined, become thixotropic and tend to
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increase viscosity quite rapidly. In some instances the
materials can be mixed and maintained reasonably fluid for
extended periods of time. The initiator and accelerator, if
` any, are selected so that the initiation of polymerization
o~ the unsaturated polyester resin syrup can be controlled
by the operator. Customarily an initiator is selected which
will require heating of the composition to initiate polymer-
ization, i.e., a so-called high temperature initiator. The
polymerization of the unsaturated polyester resin component
may commence with the step of mixing together with the aqueous
alkali metal silicate. Typical spray-up applications may
employ this polymerization procedure. At the other extreme
condition, the mixture may be formed into a desired shape for
subsequent polymerization of the unsaturated polyester resin
syrup. Sheet molding compositions and molding powders may
be formed to utilize the delayed polymerization characteristic.
; In a preferred embodiment of the invention, the unsaturated
polyester resin syrup contains powdered hydrated alumina and
the aqueous alkali metal silicate also contains hydrated
~20 alumina. The amount of unsaturated polyester resin syrup is -
minimized so that the final product possesses a low fuel content.
~; When xposed to fire, the cured prQducts resist temperature
increases initially because of the thermàl dehydration of
the hydrated alumina and thereafter by vitrification of the
.
hybrid silica, hereinafter described. Compositions which
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include hydrated alumina have a lowered smoke generating
characteristic.
According to the methods of this invention, cur~d
thermoset articles can be prepared ~rom a mixture of unsatu-
rated polyester resin syrup and aqueous alkali metal silicate
by combining the two ingredients along with a polymerization
initiator for the unsaturated polyester resin syrup. The
composition is shaped into a mass having the shape o~ the
desired article and retained in that shape until the composi-
tion is cured. The shaping may occur by molding, pressing,
casting, hand-lay-up, spraying onto a substrate, trowelling,
extrusion, rolling and the l1ke. Suitable substrates include
metal sheets (building panels, floor decking); plastic sheets
(acrylic sheets, glass fiber reinforced polyester sheets);
organic foams (polyurethane foam, polystyrene~foam). The
polymerization initiator can be included in either of the
two components. Where a high temperature initiator is
employed, it is preferred that the initiator be included in
; ~ the unsaturated polyester resin Where a room temperature
-~ 20 ~ initiator is employed, it is preferably included in the aqueous
alkali metal silicate solution. In that circumstance, a -~
polymerization accelerator will be included in the unsaturated
. .
polyester resin syrup. The two components can be mixed in -~
~ ~ a mix;ng tank or pipe. The two components can be separately
formed into sprays which are caused to impinge upon one - -
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another and thereby accomplish the desired mixing. The two
components can be combined in a mixing chamber and sprayed
as a mixture. Either or both of the two components can
include inert fillers. ~referably with bulking agents such
as finely divided perlite or expanded vermiculite, the inert
fillers are added to the components after they have been
mixed.
A particularly preferred product resulting from the
practice of the present invention is a fiber reinforced
laminate article which includes randomly oriented reinforcing
fibers which are dispersed in a continuous phase of the
thermoset resinous composition. The resinous composition in
its cured form includes unsaturated polyester resin cross-
linked with the copolymerizable monomer of the polyester
resin syrup. However the unsaturated polyester resin-is
substantially free of uncombined carboxylic acid radicals
and instead includes alkali metal carboxylate salts. In
this respect the cured resin component differs from the
:. ~ .
cured~unsaturated polyester~resin products of the prior art.
~ Moreover the S102 content~of the resulting product exists
primarily in the form of a hybrid colloidal silica gel homo-
geneously dispersed throughout the cross-linked unsaturated ;~
- ~ . . .
polyester resin syrup which contains carboxylate salt end
groups.
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The laminates preferably include glass fibers as the ~
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reinforcing fibers in amounts from about 6 to 30 percent of
the weight of the laminate. The laminates may be further
reinforced by including as A core a sheet of expanded metal
lath
Typical products of the present compositions are cast
articles such as furniture, frame moldings, lamp bases,
statuary, skeet targets, toys; molded articles such as auto-
mobile surface elements, electrical housings; hand-lay-up or
spray-up arti~les such as boat hulls, bathroom sinks, tubs
and shower stalls, cargo containers; reinforced laminates - :.
such as building construction panels, ventilator components, : :
hoods, ducting, ceiling tiles, window frames, doors, cast-
in-place or spray-in-place articles such as fire resistant
coatings.
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~: 15 ~-.BRIEF DESCRIPTION OF T~E DRAWING(S)
~: FIGURE 1 is a ternary diagram illbstrating suitable ; :
compositions of the three component system including water,
~ sodium oxide and silicon dioxide;
; ~ FIGURE 2 is a graphical presentation of viscosity data;
: . ~: . : . . :
~ ~IGURE 3 is a reproduction of three infra-red spectra :~ -
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~ - for ingredients and products of this invention, 3-A, 3~B, 3-C.
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DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
According to this invention useful products are prepared
by mixing ~ ~
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1. a pourable and/or sprayable polymerizable
unsaturated polyester resin syrup which may be a
llquid or a paste in which the syrup is unfilled or
is filled with acti~e fillers such as hydrated alumina
or other hydrated metallic salts or oxides and/or is
filled with inert fillers such as silica, calcium
carbonate; and
2. a pourable and/or sprayable liquid con-
sisting of aqueous alkali metal silicate solution
which may be unfilled or may be filled with active -
., ~ '
fiLlers such as hydrated alumina or other hydrated
metallic salts or oxides and/or may be filled with
inert fillers such as silica, calcium carbonate.
A polymerization initiator for th~e unsaturated polyester resin
syrup is included in the mix.
~ ~ Unsaturated polyester resin syrup customarily is acidic
:~ : and has an acid number which is the milligrams of potassium
. , ~ . ~ .
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~ hydroxide required to neutralize 1 gram of the resin. The
; ~ ; acld number usually~ i6 reported on the basis of "100 percent
solids". This refers to the unsatarated poIyester resin alone
without the dilution of the copolymerizable monomer. For the
present composition6, the unsaturated polyesters are prsferrsd
~ . .
with an acid number from 10 to 100 on a 100 percent solids
hasis.
The aqueous sodium silicate is highly alkaline. The pH
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of the resultin~ composition of this invention is alkaline,
i.e., the pH is above 7Ø
The mix may be further extended, after mixing, by com--
I binin~ into the mixture inext fillers such as refractory
aggregates, ground glass, glass microspheres, silica, magnesium
oxide, mullite, flyash, zirconia, clays, bentonite, kaolin,
attipulgite, titanium dioxide, antimony oxide, pigments, low
density insulating materials, such as perlite or expanded
vermiculite, fibrous reinforcing material such as glass
fibers, asbestos fibers, mineral wool. Inert fillers tend
to increase the density or to decrease the density of the
final product according to the selected filler, and may tend
to reinforce the resulting product, particularly where fibrous
fillers are selected. Incombustible fillers also disperse
the combustible components and consequent1y lower the fuel
content of the final product. Fillers can comprise from O.Ol
to 5.0 parts by weight for each part by weight of the mix.
The materials of this invention are pre~erably cured
~ .
at temperatures below about 100C to minimize the vaporizing
tendency of the water content of the aqueous alkali metal
silicate. Excessive curing temperatures may cause rupturing
or spalling of the resultin~ shaped article. When the two
li~uids are mixed, along with suitable fillers, the consistency
of the product is similar to potter's clay in a preferred
embodiment. In this consistency the mixture can be troweled
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and can be applied to horizontal, vertical and overhead
surfaces by troweling, rolling, pressing or extrusion as
desired to produce coatings. The mixture also can be in- -
jection molded/ press molded or employed in hand-lay-up
operations or in casting operations.
Preferably the viscosity of the unsaturated polyester
resin syrup ranges from about 50 to 5,000 centipoises.
FIGURE 1 is a ternary diagram illustrating the three
component system: water, Na2O, SiO2. The aqueous sodium
silicate compositions which are useful in this invention
are shown in the shaded areas of the diagram, i.e.,
ta) water content 45 to ~5 per cent by weight,
(b) SiO2/Na2O ratio 1.5 to 3.75 by weight (i,e., 21%
to 40% by weight Na2O, balance SiO~) as shown by the two
broken lines.
; The increasing viscosity which occurs upon mixing
aqueous sodium silicate with unsaturated polyester resin
syrup appears to be the result of several competing phenomena
which are principally: ~ ~
(A) The formation of carboxylate salts by reaction of
the unreacted carboxylic acid groups of the unsaturated poly-
ester resin wit.h the alkali metal ions of the aqueous sodium
silicate;
(B) The conversion of the sodium silicate to a hybrid
silica gel.
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A number of factors influence the rate of viscosity increase
including:
the weight ratio o~ SiO2/Na2O;
the acid value of the unsaturated polyester resin;
the initial viscosity of the unsatura,ed polyester resin
- syrup and of the aqueous alkali metal silicate
solution.
To some extent the viscosity increase depends upon the amount
and identity of polymerizable monomer included in the un-
saturated polyester resin syrup; also the identlty and
concentration of the particulate fillers, if any, in the
mixture may affect the viscosity increase.
While it is possible to produce unsaturated polyester
resins with very low acid numbers, these materials are not
generally commercially available because of the~excessive
cooking times required to lower the acid value. Moreover
; : , .
the unsaturated polyester resins with relatively high acid
values tend to be more stable than the very low acid value
unsaturated polyester resins. In the present process, the
caustic sodium silicate solution tends to neutralize the
acidity of the unsaturated polyester resin; at the same
time the unsaturated polyester resin is lowering the pH of
the sodium silicate solution, thereby upsetting the silicate
equilibrium and causing formation of a hybrid silica gel.
In the resulting cured product,~the continuous phase comprises
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the hybrid silica gel and also comprises cured unsaturated
polyester resin cross-linked with the copolymerizablè
monomer wherein the resin contains alkali metal carboxylate
salt groups.
Silica gels are known to exist in at least three dif-
ferent types including a polymerization gel, a flocculation
gel, and a mixed or hybrid gel.
The polymerization gel results from the conversion of
aqueous sodium silicate to silicic acid by neutralization.
The polymerization gel consists of polysilicate ions ex-
tended as a three-dimensional, cross-linked network through-
out the solution. The flocculation gel occurs when preformed
colloidal silica particles combine through junction points
with siloxane bonds. The hybrid gel appears to be a combina-
tion of the first two forms of gel and includes preformed
colloidal silica particles joined by polysilicic acid chains.
hese hybrld gels can be synthesized by gradually neutralizing
mixtures of silicates and colloidal silica sols.
In general, the cured products obtained by polymerizlng
~20 the alkaline mixtures of unsaturated polyester resin syrup and
aqueous alkali metal silicate will contain at least 5 percent
by weight of the hybrid colloidal gel homogeneously dispersed
with the cross-linked unsaturated polyester resin syrup
wherein at least a portion of the cross-linked polyester
contains carboxylate salt end groups in its polymerized state.
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The carboxylate salt phenomenon will be discussed in
connection with three infra-red spectrum analysis charts
supplied as FIGURE 3. An infra-red spectrum analysis,
FIGURE 3-A, was obtained ~or an unsaturated polyes-ter resin
syrup II. The unsaturated polyester resin syrup II is pre-
pared from 90.3 mols propylene glycol, 12.5 mols dipropylene
glycol, ~3.75 mols phthalic anhydride and 56.25 mols maleic ..
anhydride, cooked to an acid value of 30 to ~0. 73 parts by
weight of the polyester are combined with about 27 parts by
weight of styrene to produce the polyester resln syrup II.
A characteristic carboxylic acid ester linkage response is
prominent at about 5.7-5.8 microns as indicated by the numeral
6.
Equal weights of aqueous sodium silicate grade N and
resin I were mixed, dried and analyzed by infra-red spectrum
analysis to produce the chart of F:CGURE 3-B. The dried sample
: shows a small concentration of the carboxylic acid ester
linkage at about 5.7 - 5.8 microns, as lndicated by the .
numeral 7, and shows a prominent concentration of a carboxy- .
late salt at about 6.3 microns as indicated by the numeral 8.
It was necessary to dry the sample of the mixture of unsaturated
polyester resin syrup and aqueous sodium silicate in order to
prevent interference with the potassium bromide plates which
are employed in the infra-red spectrum analysis equipment.
25 A 50/50 weight mixture o[ aqueous so~ium sllicaee grad~
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N and unsaturated polyester resin syrup II was cured and
analyzed. The spectrum analysis is presented in FIGURE
3-C. A prominent concentration of carboxylic esters
appears at 5.7 - 5.8 micr,ons, as indicated by numeral 9,
and a prominent concentration of carboxylate salt appears
at about 6.3 microns, as indicated by the numeral 10.
It appears that the cured polymeric product possesses
' a substantial amount of carboxylate salt.
Examples of the present invention will further illus-
10 trate its utility.
Example 1
An unsaturated polyester resin syrup (hereinafter
identified as resin syrup I) contains 25 parts by weight
styrene and 75 parts by weight of t'he unsaturated polyester
lS resin which is obtained as follows: ,
.
60 mols phthalic anhydride
. , .
40 mols maleic anhydride
106 mols propylene glycol
' are combined and esterified to an acid number of about 20
to produce a general purpose unsaturated polyester resin
which is employed in most of the examples hereinafter. One
gram of benzoy,l peroxide powder is added to 100 grams of the
unsaturated polyester resin syrup I as a catalyst. This
.
unsaturated polyester resin syrup is combined with 100 grams
of aqueous sodium silicat~ containing 63 per cent by weight ,
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water and 37 per cent by weight dissolved solids. The
weigh-t ratio of SiO2/Na2O is 3.2. This aqueous sodium
- silicate is commercially available from ~hiladelphia
Quartz Company and is identified as silicate N.
~ollowing mixing of the two liquids, the mixture
thickens rapidly and has the appearance of white paste.
The mixture was applied to a sheet of cellophane within a
1/2 inch diameter tubing O-ring having a 6 inch ring
diameter. A second sheet o cellophane was applied on top
of the 0-ring and the resulting cellophane sandwich was
pressed to produce a disk 1/2 inch thick and 6 inches in ~ -
diameter. l'hat disk was placed in an oven at 90C. for about
15 minutes. The disk was allowed to set overnight and lost
some water content through evaporation. The disk had a chalky-
white appearance and a density of 0.75. Thereupon the disk
was placed on a ring stand approximately 2 1nches above a
; sunsen burner. The Bunsen burner ~lame impinged upon the
disk. Within the first S minutes of impingement some small ~-
amount o~ smoke was detected. Thereafter no smol~e was ob-
.
served. The dis~ remained over the Bunsen burner ~or 6 hours.
- Throughout the flame exposure, the dis~ retained its shape
and integrity.
Example 2
; Example 1 was duplicated except that the unsaturated -~
polyester resin syrup I was modified by including two drops
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of Triton X-100, trademark for a non ionic surfactant
consisting of a polyethylene glycol alkyl arylether avail-
able from Rohm & Haas Company. The aqueous sodium silicate
contained one drop of Triton ~-100 per 100 ~rams. Equal
parts of the resin syrup and the silicate were mixed and
formed into a disk 1/2 inch thick and 6 inches in diameter.
This dis]s was tested in the manner described in Example 1
with the same resultsO A conclusion from Example 2 is that
the absence of a surfactant (Example 1) is indistinguishable
from the presence of a surfactant (Example 2).
Example 3
50 grams of the unsaturated polyester resin syrup I
is combined with 50 grams of alumina trihydrate, minus-325
mesh U.S. standard screen, and 0.5 gram benzoyl peroxide
powder to form component 1. 50 grams of aqueous sodium --
silicate ~l is combined with 50 grams of alumina tri-
hydrate, minus-325 mesh U.S. standard screen, to form
component 2. When the alumina trihydrate is mixed ;
with the aqueous sodium silicate, a thixotropic slip is
formed having a viscosity of 70 to 6000 cps (srook~ield).
Component 1 and component 2 are mixed together and formed
into a disk 1/4 inch thick and ~ inches in diameter. The
disk is cured in an oven at 90C. for 15 minutes. The disk
has a chalky-white appearance and is tested as described
in Example 1. Essentially no smoke or flame is detected
throughout the 6 hour test. The burnt out di~k appears to
:;
. .
-22-
.
.~ ,,,
be a continuous, lightweight composition.
Example 3 illustrates a composition extended with
equal weights of alumina trihydrate based on the combined
weight of unsaturated polyester resin syrup and aqueous
sodium silicate.
Exam~le ~ '
.: '
Example 3 is repeated except that 10 grams of perlite
(minus-40 mesh U.S. standard screen3 is thoroughly mixed
into the mixtur,e of component 1 and component 2. The composi-
tion is shaped into a disk 3/8 inch thick and 3 inches in
diameter. The disk is cured and tested in the manner
described in Exampl~ 1. No smoke or flame is dctected during
the test, After the samplq has been over the Bunsen burner i'i '
; flame for one hour, the topside can be touched by hand
; 15 without discomfort indicating that the material possesses
outs-tanding thermal insulation characteristics. '~'
Example 5
` ~ Example 3 is repeated with two variations. The first ~ '
.
variation is that the alumina trihydrate is minus-100 mesh
U.S. standard screen. The second variation is that the '
.
aqueous sodium silicate component contains 0.1 grams N,N'-
di'methyl aniline as a polymerization accelerator. Components
~ ~1 and 2 are mixed and formed into a disk 1/4 inch thick and
; 4 inches in diameter, The sample cures at room temperature
~ 25 in about one hour. This example indicates the feasibility
.........
-23-
. .
of providing a polymerization catalyst in the unsaturated
polyester resin syrup and providing a polymerization accel-
erator in the,aqueous alkali metal silicate.
' Exam~le 6
Example 3 is repeated with one variation. Component 1
consists of 50 grams of polymerizable unsaturated polyester
resin I and 50 grams of alumina trihydrate (minus-325 mesh
U.S. standard screen) and 0.1 gram methyl ethyl ketone
peroxide ~60% solution in dimethyl phthalate) and 20 drops
cobalt naphthenate (6% solution in glycol). The viscosity
of component 1 is about 4000 to 5000 cps (Brookfield). Com-
ponent 2 is the same as in Example 3. Components 1 and 2
are thoroughly mixed and shaped into a disk 1/4 inch thick
and 4'inches in diameter. The disk cures in approximately
45 minutes at room temperature.
This example indicates the feasibi1ity of providing a
catalyst and an accelerator in the unsaturated polyester
resin syrup.
Example 7
A number of disks were prepared employing component 1
.
,~ and component 2 a,s described in Example 5. The ratio of '
component l/component 2 was 80/20, 60/40, 50/50, 40/60,
, 20/80, and 10/90. Each of the formulations was formed into ~ ,
a disk 1/4 inch thick and 4 inches in diameter. Each disk
,25 ' was tested as described in Example 1. The results of the
. ' ' ' ' , .
~ ' ' .
-2~-
, ' ~ .
tests are set forth in the following table.
Table I
Component 1 Appearance
Component 2 , After 6 HrsO
~E~ By WeiqhtSmoke Flame Burnin~ _
A 80/20 - Heavy -Fell Apart
B 60/40 - Light -Eell Apart
Very
C 50/50 Light LightFair
. ~, . .
D 40/60 - Very Light - Good
E 20/80 - Hard to Detect -Very Good
., .
F 10/90 - Hard to Detect -Excellent
It will be observed from Table I that the specimens
(A, B) with a high content of unsaturat~d polyester resin ~-
~syrup tend to produce smoke, flame and to deteriorate when
! . j: ~ '
~ exposed to burning. As the amount of unsaturated polyester
~ . -
; ~ resln syrup is decreased, the amount of smoke and f~lame de-
creases and the resistance to burning increases. The materi-
-
, als become increasingly difficult to mix as the amount of
, ....... ....... .................................................................. ... .... .
unsaturated polyester resin syrup is diminished. Specimens
A, B, C and D mix readily. Specimen E is a little difficult
to mix. Spe~imen F was quite difficult to mix~ The mixing
,
difficulty arises from the tendency of the mixed materials to
increase rapidly in viscosity.
!, ' ~
~'74~
Exam~le 8
.
Example 3 is repeated with the exception that component
2 is formulated from 50 grams of aqueous potassium silicate
solution containing 71 per cent by weight water and 29 per
cent by weight dissolved solids having a weight ratio of
Sio2/K2o of 2.5. Component 2 also includes 50 grams of alumina
tri~ydrate (minus-325 mesh U.S. standard scree~). Components
1 and 2 are blended together and shaped into a disk 1/4 inch
thick and 4 inches in diameter. The disk is cured by heating
at 90C. The disk i5 tested as described in Example 1. Almost
no smoke or flame is detected during the test~ The burnt
material after 6 hours exposure to the flame is a continuous
lightweight composition.
~his example indicatas that aqueous potassium silicate
~ is effective in the same manner as a~ueous sodium silicate.
:-'' ~ ' , .
A sprayable system is prepared by assembling ingredients
in the manner to be described.
Component 1
Unsaturated polyester resin syrup I 16 pounds
Styrene 3 pounds
Benzoyl peroxide powder 0.9 pounds
Triton X-lO0 (surfactant) 0.25 pounds
Aluminum oxide trihydrate (minus-325
mesh U.S. standard screen) ?3 pounds
Total 43.15 pounds
-~6-
.
.. .. . .
. . .
.. , .. :. .: : . .
~ ~'7~
Component _ -
Aqueous sodium silicate (as in
~xample 1) 10 pounds
Water 10 pounds
Styrene 0.5 pounds
N, N' -dimethyl aniline 1 ounce
Triton X-100 (surfactant) 0.25 pounds
Aluminum oxide trihydrate (minus-325
mesh U.S. standard screen)30 pounds
Total 50.8 pounds
~ote: The ~ dimethyl ani~ine i9 dissolved in the
styrene and the solution is added to component 2.
Components 1 and 2 are sprayed on various substrates by
two different methods.
Method 1 - A dual head spray gun includes two
; separate spray heads. Component 1 is sprayed through
one spray head; component 2 is sprayed thxough the
other spray head. The sprays are impinged approxi-
mately 6 inches beyond the spray nozzles to achieve
intimate mixing.
Method 2 - A spray gun having a mixing chamber
is employed in such manner that component 1 and com-
ponent 2 are mixed within the mixing chamber and
sprayed as a mixture onto the substrate.
In both spraying systems, a glass ~oviny chopper is positione~d
ad~acent to thc spray patterns to deposit chopped glass ibers
',"',, "''.
-27-
.. . " . . . : . .
~7~4~L
approximately 2 inches long into the spray patterns in
order to incorporate the glass fibers into a spray-up
composition. The sprayed compositions have been applied
` to ordinary steel sheets, galvanized steel sheets, glass
fiber reinforced polyester resin panels, a dry wall, a wood
p]ank, an acrylic resin sheet, a sheet of paper, a sheet of
stainless steel, a concrete surace, a sheet of expanded
metal lath, a cotton cloth, a polyester fiber cloth, a
sheet of leather, a sheet of rubber, a sheet of rigid poly-
` 10 urethane foam and a glass plate. In all cases the sprayed-
on material adheres well to the substrate. Adhesion is
obtained with substrates disposed vertically, disposed in
- a sloping position, disposed horizontally below the spray
and disposed horizontally above the spray. The resulting
coatings have been produced in thicknesses from about 1/16
.
inch to thicknesses of several inches. Curing of the coat-
ings occurs within a matter of several minutes.
It will be observed that component 1 contains an ab-
normally high quantity of benzoyl peroxide as a catalyst.
,
~20 The reason for employing excess catalyst in these tests is
to assure prompt ~curing of the composition in order to permit
.
~andling of the coated substrate in a very short period of
time following the spraying.
, .
, ; ~ Additional styrene is included in this series of tests
to facilitate the spraying of component 1. ~ ~
~: ' ' . . . .
' :.
.
:::; .',' . :
~: :: :, .
The additional water in Example 9 is added to lower
the viscosity of component 2 to facilita-te spraying.
It will also be observed that the total formulation
contains more than 56 per cent by weight alumina trihydrate.
The two components 1 and 2 are sprayed in approximately
equal weight ratios.
Example 10
The form~lations described in E~ample 9 are applied to
both sides of a sheet of expanded metal lath to produce a
panel. The expanded metal lath was 2 feet by 8 feet. The
product can be prepared in the following manner. A sheet of
cellophane is spread on a table. A coating of the present
composition along w;th approximately 6 per cent by weight
glass fiber is applied to the cellophane sheet. Thereafter
a sheet of expanded metal lath is deposi-ted on~top of the
` composition and rolled for partial embedment in the composi-
tion. Thereafter an additional coatin~ of the present compo-
sition along with approximately 6 per cent by weight glass
fibers is applied on top of the expanded metal lath. The
top coating is covered with another sheet of cellophane and
the panel is allowed to cure.
A panel produced in this ~ashion was 3/8 inch thick.
The paneL just described was subjected to a flame spread
tunnel test similar to the ASTM E84 t~nnel test~ The panel
.
2~ rated as follows:
.
' .
''
-29-
'", ' ~
Flame spread 7.69
Smoke generation 1,56
Example 11
A building was sprayed with the present coating compo-
sition. The building was a corrugated metal panel building
having a cen-trally pitched roof. The roofing panels were
- uncoated steel surfaces. The vertical side wall panels had
been previously coated with a spray-applied polyurethane
foam coating approximately one inch thick as thermal insula-
tion. The vertical walls had a total surface area of about
4,000 square feet~
Component 1 of the coating composition was prepared by
combining:
unsaturàted polyester resin syrup I - 45 pounds;
hydrated alumina, minus-325 mesh U.S.. standard
screen - 50 pounds;
benzoyl peroxide (50 per cent by weight in a
suitable plasticizer) - 1 pound~
Component 2 was prepared by combining:
~20 ~ N grade aqueous sodium silicate - 35 pounds;
water - 10 pounds; -
- :
hydrated alumina, minus-325 mesh U.S. standard
.
screen - 70 pounds;
~ dimethyl aniline - 125 grams.
Components 1 and 2 were introduced at equal flow rates
''. ~ .
.
'
-30-
~7'~
separately into the two spray heads of a dual head spray
- nozzle. The spra~ nozzle developed two cone sprays which
- impinged at a distance of 4 to 6 inches from the spray tips,
The spray nozzles utilized exterior air atomizing. Com-
ponents 1 and 2 were pumped at pressures of about 150 psi.
The atomizing air pressure ranged from 40 to 90 psi. A
chopped glass roving gun provided 1 inch long chopped strands
of glass fiber roving at the region of spray impingement.
A fire retardant coating was spray-applied to the
1~ interior of the building over the polyurethane foam thermal
insulation and also over the interior metal surfaces of the
pitched roof panels. The coating was applied in three se-
quential operations as follows:
First step: A thin film of the two mixed liquid sprays,
without glass fibers, was applied to a selected small area
of the wall surface in order to wet the surface. ~ -
Second step: A film of glass fibers plus the mixed
sprays was applied to the wetted surface.
- Third step: A furth~er film of the mixed sprays without
glass fibers was applied on top of the coatings.
No deliberate attempt was made to roll the coating.
Instead the glass fibers were allowed to settle as applied.
Preponderantly the fibers laid flat upon the wall surfaces.
The films adhered well to the foam surface and also to the
bare metal roof panels. The thickness of the coating was - ~
`'
'
_31-
~ ~ 7 ~ ~ ~
varied intentionally to permit observation of the effect
of different thicknesses. Thicknesses ~rom about 1/16 inch
to about 1/4 inch were applied and observed. Coating thick-
nesses in this range had no observable effect on the adhe-
sion properties.
Within about one hour after application the coating was
free of tackiness.
; The building interior was entirely coated with the
described coating material. The coating serves as fire
protection for the polyurethane foam thermal insulation on
the vertical side walls. The function of the coating on the
bare metal pitched roof panels in this installation is merely
to demonstrate the adhesion characteristics. The present
coatings would not normally be applied to the interior sur-
faces of bare metal pitched roof ceilings. However the ;~
present coating compositions have utility as fire barrier
coatings when applied to the metal undersurfaces of steel --
floors.
Example 12
Spray-up laminates were prepared on a Cellophane* sheet
with the formulation and equipment described in Example 11.
ASTM samples 1/8 inch thick were prepared and tested. The
samples contained 20 per cent glass fibers by weight. The
observed physical properties were:
. .
*Trademark
' ~
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.
-32-
: ':
flexural strength - 8,873 psi
flexural modulus - 0.369 x 106
tensile s-trength - 5,521 psi
tensile modulus - 0.437 x 106
Added samples of this spray-up laminate, 14 centimeters
long, 5 centimeters wide and a nominal 1/8 inch thick, were
obtained. The density of the samples averaged 1.3 after
drying at room temperatureO These samples were exposed for
4,000 hours in weather-o-meter tests as described in National
Bureau of Standards Publication 260-15 using Standard Refer-
ence Material 701-c. The samples exhibited some chalkiness
on their surface. The samples retained whiteness and exhibited
no gross deterioration.
Added samples of the spray-up laminate as described were
; 15 placed in a condensing humidity cabinet at 150F. for 2500
hours exposureO The samples exhibited slight surface chalk
and had no color change or loss of integrity.
The effect of viscosity lncrease was illustrated by
adding aliquot portions of aqueous sodium silicate to un-
saturated polyester resin syrup I. 546 grams-of polyester
.
resin syrup I contains approximately 200 milliequivalents
of carboxylic acid groups.
Aqueous sodium silicate N was added in aliquot portions
o~ about 5,7 grams each. Each aliquot contained about 20
,
-33-
milliequivalents o~ caustic.
The viscosity of the mixture was measured after each
sodium silicate aliquot was added. The viscosity increase
is shown in FIGURE 2 wherein the viscosity in centipoises
is plotted as the Y axis and the weight of added aqueous
sodium siliaate is plotted as the X axis. Initially the
viscosity of the resin syrup I alone was about 400 cps,
Point 1 on the graph. Following the mixing of a first ali-
quot of the aqueous sodium silicate, the viscosity increased -
to about 850 centipoises. The viscosity continued to in-
crease approximately linearly until about 7 alîquots of the
aqueous sodium silicate had been added, Point 2 on the graph.
Thereafter the viscosity continued to increase sharply until ~
the tenth aliquot was added, Point 3 on the graph. There- -
after the viscosity increased only gradually wLth ~urther
additions of aqueous sodium silicate. The additions were
~ di continued after the 17th addition~ Point 4 on the graph,
; at which time the viscosity was about 117,000 centipoises.
~ .
The following day the viscosity was measured again and
:` .
~20 found to be about 750,000 centipoises, Point 5 on the graph
FIGURE 2 illustrates in a graphical manner the existence
o~ multiple competing phenomena which influence the viscosity
increase when a~ueous sodium silicate is added to unsaturated
polyester resin syrup ha-~iny a relatively high acid value, ;
specifically, about 20 in Example 13. ~he cohtinuing increase
- ' '
'
-3~~
- .. . : : .
'' . . ~,, , ~::
.. . . . . .
in viscosity with time, compare Points 4 and 5, suggests
that the material can be worked by spraying or troweling
or reasonable periods of time, The unsa,turated polyester
resin syrup of Example 13,contained no curing catalysts.
Example 14
~; . ' ' .
The thermal insulation characteristics of the present
materials were determined by comparing the temperature
increase of an uncoated galvanized steel sheet against the
temperature increase of a galvanized steel sheet coated with ~,
1/4 inch of a formulation hereinafter described. Specifically
a galvanized sheet, 18 gauge, 6 inches by 8 inches was placed -~
against the open door of a muff1e :Eurnace. The interior '~
temperature of the muffle furnace was maintained at 1500F.
'' The room surface of the steel sheel: leveled off at 1400F. '
, 15 Thereafter the lnterior temperature of the muffle furnace '~ '
, was increased to 1900F. and the room surface of the galva-
nized steel sheet leveled off at 1800F.
~An identical sheet of galvanized steel was coated with
' a 1/4 inch thick~coating of a formulation hereinafter de~
20, scribed. The coating was applied to the steel by trowe1ing.
The steel sheet was placed against the open door of the muffle
furnace and the coated surface was exposed to the room. The
.
' muffle furnace temperature was maintained at 1500F. and the
-~ ~ outside témperature of the present coatiny leveled off at
about 720F. Thereafter the muffle furnace temperature was
' ~
,' ' . , ~
-35-
. .
increased to 1900F. and the outside surface of the coated
steel sheet leveled off at about 980F. This Example 14
illustrates the use of the present formulations in thermal
insulati}lg compositions. The thermal insulating compositions
are particularly attractive in coating exposed steel sur-
faces in buildings.
The formulation of Example 14 includes:
An unsaturated polyester resin syrup formed from 6 mols
phthalic anhydride, 4 mols maleic anhydride and 11.5 mols of
propylene glycol cooked to an acid value of 16-21. 71 parts
by weight of the polyester are combined wit~ 29 parts by
weight styrene to produce an unsaturated polyester resin syrup
III. The coatlng of Example 14 was prepared by combining:
500 grams - unsaturated polyester resin syrup III;
1 gram - Triton X-100, a non-ionic surfactant of
Rohm & Haas Company,
1000 grams - aluminum oxide trihydrate, m1nus-100
mesh U.S. standard screen;
125 grams - aqueous sodium silicate M grade;
250 grams added water.
The ingredients were mixed to produce a putty-like composition.
200 grams of the putty-like compositlon were mixed with 50
grams agricultural grade perlite, sized to about 1/8 inch
and finer. Then 1 gram of benzoyl peroxide was added to pro-
.. .
duce t~e co~ting material.
', : '
:~:
-36-
. : . , :
.
:' . . ' ', ' ~ ~, ,'' :' , ,, .:.. :
Added samples of the composition of Example 14 were
prepared by troweling a 1/4 inch coating onto a sheet of
galvanized steel, about 1 inch by 4 inches. The coated
steel sheets were placed in a beaker of tap water so that
the lower half of the sheets (approximately 1 inch by 2
inches) was immersed for 100 hours. Followlng this ex-
posure, the coating appeared to be identical throughout,
indicating water insensitivity.
Example 15
A polyester resin was prepared by combining 13 mols
propylene glycoll 6 mols phthalic anhydride and 4 mols
maleic anhydride. The resin is cooked to an acid value
of about 8 to 10. Thereafter 70 parts by weight of the
resin is cornbined with 30 parts by weight styrene to pro-
duce an unsaturated polyester resin syrup IV.
Component 1 of a cold molding composition was prepared
by com~ining 432.4 grams of unsaturated polyester resin syrup
IV, 64.9 grams styrene, 5.4 grams Triton X-100 non-ionic
surfactant and 497.3 grams powdered aluminum oxide tri-
hydrate. ~ ~ ~
-~ Component 2 was prepared by cor~inlng 290.4 grams o
aqueous sodium silicate grade N, 193.6 grams water, 9.8 grams
styrene, 1,3 grams dimethyl aniline, 4.9 grams Triton X-100
.:
non-ionic surfactant and 500 grams powdered aluminum oxide tri~
. I . .
:j . .
' 25 hydrate. 10.~ grams of benzoyl peroxide was added to the - ~
. ' :
-37-
- , .: . . ' ~ ,
component 1 along with 200 grams of 1/4 inch chopped
glass strands of the type customarily employed in pre-mix
- molding compositions. Thereupon one par,t of component 1
by weight and one part of component 2 by weigh-t were com-
bined to produce a molding composition. A sample of the
molding composition was introduced into a pie plate mold
and pressed at room temperature. The uncured, shaped pie
plate was removed from the p~ess and allowed to sit over
night until cured at room temperature, After 64 hours,
the pie plate exhibited a weight loss of 13.59 per cent
indicating dehydration.
Following about a week ASTM properties of the pie
plate samples were measured as fol:Lows:
flexural strength - 1,526 psi
, flexural modulus - 0.338 x 106
tensile strength - 425 psi
tensile modulus - 0.3125 x 106
Exam~le 16
A further example of cold molding articles with the
present formulations also employed unsaturated polyester
resin syrup IV. Component 1 was prepared by combining
432.4 grams of unsaturated polyester resin syrup IV, 64.9
grams styrene, 5.4 grams Triton X~100 non-ionic surfactant~
"
4g7.3 grams powdered aluminum oxide tri~ydrate and 5.4 grams '
.25 ' hydroquinone. Component 1 also received 10.80 grams benæoyl
.~ . , .
-3~-
:
~37~
peroxide. 200 grams of chopped glass fibers, 1/4 inch~ong were added to component 1.
Componen~ 2 was prepared by combining 242 grams aqueous
sodium silicate, yrad~ N" 242 grams water, 9.80 grams styrene,
1030 grams dimethyl aniline, 4.9 grams Triton X-100 non-
ionic surfactant and 500 grams powdered aluminum oxide tri-
hydrate. The materials when mixed in equal amounts exhibited ~`
a gel time of 4 minutes. The materials were introduced into
a pie plate mold at room temperature and pressed ~he pressed
pie plate was removed and allowed to sit at room temperature
overnight to cure. About a week after the cure, samples
were cut from the pie plate and ASTM evaluations,were carried
out as follows:
flexural strength - 2,252 psi
flexural modulus - 0.211 x 106
tensile strength 895 psi
tensile modulus - 0.253 x 106
Examples 15 and 16 demonstrate that the present formu-
lations can be employed to produce useful cold molded
products, e.g., statuary, toys.
~xam~le 17
Several compositions were prepared with commercially
available aqueous sodium silicates other than the heretoore
described N grade.
50 grams of the unsaturated polyester resin syrup I was
.~ ' , ' :
-39-
4~
combined with 0.5 grams benzoyl peroxide to constitute
component 1. Component 2 was prepared by combining 50 grams
of aqueous sodi~m silicate and 0.05 gram of dlmethyl aniline.
In Example 17-A, the aq~eous sodium sillcate had a SiO2/Na2O
ratio of 2.50 and a water content of 62.9 weight per cent.
In Example 17-B, the aqueo~s sodium silicate had a SiO2/~a2O
ratio of 2.0 and a water content of 55.9 weight per cent. In
both Examples 17-A and 17-B components 1 and 2 were combined
in a paper cup and stirred with a spatula. The mixture turned
white, thickened and cured in the same manner as set forth
in Example 1.
; Example 18
Molded resinous bathtubs were fabricated with the present
composition. The bathtubs wexe fabricated from a vacuum
.
formed thermoplastic acrylic sheet having a nominal thickness
of about 15 mils. The thermoplastic sheet was drawn into a
mold having the shape of a bathtub and thereafter removed
from the mold and supported in a suitable jig. Using foxmula-
~ tlons herelnaftex to be described, three specific bathtubs
; 20 were fabricated by hand-spxay-up techniques, One bathtub had
- an approximately 1/8 inch thickness coating of the present
1:
~ composition; another tub had a 3/16 inch average thickness
- . ,
. ~ . .
coating; the third tub had a coating of approximately 1/4 inch
average thickness. The coatings were applied by spraying an
unsaturated polyester resin syxup into a spray of aqueous
~, `, .
:, , . ' '
: .
,: ,
~40~
.. . .. ... . . .. .
,, ' ' ' I
.
~7~
sodium silicate. The two sprays impinged upon a downwardly
flowing stream of chopped glass fibers from a glass fiber
roving chopper. The coating adhered to the convex surface
of the vacuum formed thermoplastic acrylic sheet and was
hand rolled and worked to embed the fibers. The fibers con-
stituted 25 to 30 percent of the weight of the coating. The
resin mixture contained
50 pounds of an unsaturated polyester
resin hereinafter to be described,
10 pounds styrene,
27.4 grams hydroquinone,
40 pounds finely divided hydrated alumina
(100 percent -325 mesh U.S. standard screen), and
544.8 grams benzoyl peroxide. ~-~
lS The aqueous sodium silicate included
20 pounds of N grade aqueous sodium silicate,
20 pounds water,
60 pounds finely divided hydrated alumina
(100 percent -325 mesh U.S. standard screen), and
272 grams N,N'-dimethyl aniline.
The two liquid ingredients were maintained at 350 psi pressure
and were sprayed by means of an airstream maintained at ~30 to
100 psi. The glass fiber roving had a silane sizing and was
chopped to approximately one-inch lengthsO After 15 to 20
minutes the coatings had hardened and useful bathtubs were
removed from the jigs.
.
-41-
The unsaturated polyester resin of this example was
prepared by combining 1.06 mols of propylene glycol with
0.4 mols maleic anhydride and 0.6 mols phthalic anhydride.
The resin has an acid number of 20-26. 72 pounds of the
resulting resin are combined with 23 pounds of styrene to
produce the unsaturated polyester resin of this example.
~ .
.
~, .
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': : . , ' ~ .'
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'........ ' . ~- .
.
' ' . '
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