Note: Descriptions are shown in the official language in which they were submitted.
THERMOSETTING POLYESTER PLASTIC COMPOSITIQNS
CONTAINING BLOC~ED POLYISOCYANATE_~ND
ISOCYANATE-RE~CTIvE ~A~ERIA~
This application is a ~ontinuation-in-part
of Application Serial No. 07/767,998 filed September
3~, 1991.
Field of ~he Inven~io~
This application relates to reinforced
thermosetting polyester compositions, and more
particularly, to such compositions containing
blocked polyisocyanates plus isocyanate-reactive
material.
~ack~round of the Invention
Re;nforced thermosetting polyester-based
molding compositions in the form of sheet molding
compound (SMC) and bulk molding compound (BMC~ have
been known for many years. These materials are
based on unsaturated polyester resins produced from
a reaction between a polyol having at least 2
hydro~yl groups, and a mi~ture of saturated and
unsaturated dicarbo~ylic acids (or their
anhydrid~s). The initially formed unsaturated
polyester resin is blended with one or more monomers
capable of crosslinking with the unsaturated in the
polyester, a pero~ide catalyst, and a reinforcing
material such as fiberglass, then heated to
decompose the pero~ide and ~ause the crosslinking
reaction between the monomer and the unsaturation in
the polyester molecule to occur. The resulting
product is a composite of the reinforcing material
and the crosslinked polyester.
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-- 2 --
For many applications, an alkaline
earth-containing thickener such as magnesium o~ide
is added to the composition before crosslinking is
initiated. This is thought to comple~ with residual
carbo~yl groups of the polyester molecules, thereby
increasing the ~iscosity of the mi~ture and aiding
achievement of uniform distribution of reinforcing
filler as the mi~ture is caused to flow into its
final shape during processing. In addition to the
materials mentioned thus far, the molding
compositions also frequently contain various other
fillers, mold release agent, and other additives to
be discussed below.
A great variety of properties may be
achieved in the cured composite by appropriate
selection of the identities and amounts of the
starting diacids, polyols, crosslinking monomers,
catalysts, other additives, etc. used in the
preparation. As a result, these materials have wide
applicability in the manufacture of strong
relatively light weight plastic parts.
Historically, molding composite materials
based on thermosetting polyester resins suffered
from ~he difficulties that 1) the surfaces of molded
parts were poor, and included fiber patterns which
required costly sanding operations for painted
applications and precluded use of such materials in
high appearance internally pigmented applications; -
2~ parts could not be molded to close tolerances
because of warpage; 3) molded parts contained
internal cracks and voids, particularly in thick
sections; and 4) molded parts had notable
depressions or ~sinks" on surfaces opposite
reinforcing ribs and bosses.
.,, , . . ,:
The cause of these problems was believed to
be a high degree of shrinkage during
copolymerization of the unsaturated polyester ~esin
with the crosslinking monomer. Such shrinkage
during the crosslinking react;on causes the polymer
to pull away from the surfaces of the mold and the
fiberous reinforcements. This reduces accuracy of
mold surface reproduction and leaves fiber patterns
at the surface of the molded parts. ~he stresses
creat~d by nonuniform shrinkage cause warpage,
internal cracks, and poor reproduction of mold
dimensions in finished molded parts. It has been
shown that curing of typical unsaturated polyester
resin results in volumetric shrinkage of
appro~imately 7%.
The abo~e-discussed difficulties have been
addressed in practice by adding certain
thermoplastic material~ to the molding composite.
The presence of these therm~plastics in the
composition reduces shrinkage of the part during
curet or in some cases causes a small amount of
e~pansion, thereby providing molded parts which ~ore
accurately reflect the molds in which they were
made, and which have relatively smooth surfaces.
The surface smoothness of a molded part is
gauged by measuring its surface profile by means of
a suita~le surface analyzer. A rough surface
e~hibits a high surface profile, while a smooth
surface e~hibits a low surface profile. As the
addition of thermoplasti~ materials to the
polyester-based molding composite results in
smoother surfaces in the molded part, relative to
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~he case wit~out such thermoplastic materials
present, these thermoplastics are called "low
prof i le additives".
A number of thermoplastics have been found
to give var~ing levels of shrinkage control.
E~amples are:
a) poly(vinyl acetates). See, for
example, US Patents 3,718,714; 4,284,736;
4,288,571; and 3,842,142.
b) polymethylmetha~rylates and copolymers
with other acrylates. See, for ezample, US Patents
3,701,748; 3,722,241; 4,463,1S8; 4,D2D,036; and --
~,161,471.
c) copolymers of vinyl chloride and vinyl
acetate. ~ee, for e~ample, US Patents 9,28~,736 and
3,721,642.
d) polyurethanes. See, for example, US
Patents 4,035,439 and 4,463,158; British Patent
1,451,737; and European Patent 074,746.
e~ styrene-~utadiene copolymers and other
elasto~ers. See, for e~ample, VS Patents 4,D42,036;
9,161,471; and 4,160,7S9.
f) ~olystyrene and certain copolymers of
certain monomers. See, for e~ample, ~S Patents
3,503,921 and 3,674,893; Netherlands Patent
7~-15~86; and ~erman Patent 2,2~2,972.
9~ polycaprolactones. See, for egample,
US Patents 3,~49,586 and 3,688,178.
h) cellulose acetate butyrate. See, for
e~ample, US Patent 3,642,672.
i) saturated polyesters and various blends
of saturated poly~sters with poly(~inyl chloride).
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..... . .. ... . . . . .. . .. . .. .. . . ... . . . . .. . . .. .
See, for e~ample, VS Patents 3,989,707; 3,736,728;
and 4,263,199; Japanese Patent 4,601,783; and
Netherlands Patent 70-14~68.
These polymers, when blended in appropriate
ratios with unsaturated polyester resins and
comonomers result in shrinkage control under both
standard compression and injection molding
conditions. For optimum shrinkage control and hence
mold reproduction in particular systems, the
combinations of structures and molecular weights of
the unsaturated polyester resin and the
thermoplastic low profile additive are selected on
the basis of simple trials.
A wide variety of unsaturated polyester
resin structures has been reported in the
literature. The most eommonly used polyester
resins, however, are those based on the condensation
of 1.0 mole o~ maleic anhydride with a slight e~cess
of propylene glycol, and similar resins in which up
to 0.35 moles o~ the maleic anhydride is replaced
with orthophthalic anhydride or isophthalic acid.
The comonomer is almost always styrene.
This approach to shrinkage control can also
be applied in the case of vinyl ester resins. See
for e~ample, US Patent 3,674,893.
Progress in overcoming the above-discussed
problems of shrinkage of molded polyester-based
composite material during cure has occurred in
stages over appro~imately the past twenty-five
years. The successive improvements have been
quantified by determining the linear shrinkage of
parts and/or measuring their surface smoothness.
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The first generation of low profile
additives were materials such as polystyrene and
polyethylene. Molded parts incorporating such
additives were found to e~hibit shrinkage of sbout 2
mils per inch (0.2%), in contrast to shrinkages of 4
to ~ mils per inch (0.9-0.~%) found for composites
lacking these additives. The resulting composites
were found to accept internal pigments well, but the
surface quality of the parts was poor and the dPgree
of shrinkage, although improved relative to that of
composites containing no low profile additive, was
still objectionably high for many applications.
The second generation of low profile
additives were acrylic-based polymers such as
polymethylmethacrylate, which when employed with
specific unsaturated polyester resins prepared by
condensation ~f maleic anhydride with propylene
glycol, gave composite materials which eghibited
shrinkage of about 0.5 mils per inch (0.0~%). These
materials were found to have poor pigmentability and
poor surface smoothness by current standards.
The third generation of low profile
additives were the poly(vinyl acetate) polymers.
Such additives can be used in a wide range of
unsaturated polyester resin materials, and the
molded parts e~hibit essentially no shrinkage.
Compositions containing poly(vinyl acetate) low
profile additives have poor pigmentability, but the
molded parts have very good dimensional stability
and surface smoothness. As a result, these
materials are widely used.
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The fourth generation of low profile
additives are materials which cause unsaturated
polyester resin composite materials containing them
to tend to e~pand slightly during cure, thereby
reproducing the surface of the mold with great
accuracy. At room temperature, products made with
these additives generally are 0.3 to 0.~ mils per
inch larger than the room temperature dimensions of
the ~old. The surface smoothness of parts made with
these low profile additives equals or e~ceeds the
smoothness of automotive grade steel.
There are several varieties of fourth
generation low profile additives-
1) a poly(vinyl acetate) or otherthermoplastic polymer, plus at least one shrinkage
control "synergist'~. E~amples of shrinkage control
synergists are a) epoxide-containing materials such
as epo~idized octyl tallate, b~ secondary monomers
such as vinyl acetate monomer, which are more
reactive with themsel~es than with styrene, c)
mi~tures of such epo~ides and secondary monomers, d)
lactones such as caprolactone, e) silo~ane-alkylene
o~ide polymers, and f) fatty acid esters.
2) certain modified poly~vinyl acetate)
poly~ers which are employed with ~pecially selected
unsaturated polyester resins.
3) a standard low profile additive such as
poly(vinyl acetate), preferably acid-containing,
plus an isocyanate prepol~mer resulting from
reaction of a polyether polyol and a diisocyanate,
which provides a dual thickening mechanism.
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Despite the substantial improvements in
physical properties whi~h have been achieved in
reinforced polyester-~ased composite material~ by
use of low profile additives, further improvement in
properties such as fle~ural strength, impact
strength, and surface smoothness are still very
desirable. Additives providing one or more of these
improvements are ~he subject of the present
application.
SummarY
It has been found that addition of a
blocked polyisocyanate and an isocyanate-reactive
material to a thermosetting polyester-based molding
composition containing a low profile additive
results iD final molded parts having significantly
enhanced strength, particularly fle~ strength, as
well as well as e~cellent shrinkage control and
superior surface smoothness, relative to parts made
from such polyester-based molding compositions not ~ .
containing these additives.
The thermosetting molding composition of
the invention comprises an unsaturated polyester, an
olefinically unsaturated monomer, a thermoplastic
low profile additive, a reinforcing filler, and
further includes a blocked polyisocyanate, and an
isocyanate-reactive material which is different from
the unsaturated polyester employed in the
composition. An e~ample is a material which
contains active hydrogen atoms, such as a polyol.
A process for preparing a reinforced
thermoset molded composite includes the steps of
preparing the thermosetting molding composition of
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the invention, forming this composition into a
desired shape, and heating the shaped co~position to
cure it.
Molded articles made usiny the composition
and process of the invention are also aspects of the
invention.
Detailed Desc~i~tion
The unsaturated polyesters which are
employed in the invention are materials which are
well known to the art. Each is the reaction product
of a polyol and at least one olefinically
unsaturated dicarboxylic acid or anhydride, and may
also include residues of saturated and/or aromatic
dicarbo~ylic acids or anhydrides. The olefinic
unsaturation is prefera~ly in the B position
relative to at least one of the carbonyl groups of
the dicarboxylic acid or anhydride. The unsaturated
polyester typically has a molecular weight in the
range of 1,00~ to 2,00~, and contains residual
carboxyl and hydro~yl groups as well as olefinic
unsaturation.
E~amples of suitable unsaturated
dicarboxcyclic acids and anhydrides useful in
preparation of the polyesters are materials such as
mal~ic acid or anhydride, fumaric acid,
tetrahydrophthalic acid or anhydride,
hexachloroendomethylene tetrahydrophthalic anhydride :
(nchlorendic anhydriden), itaconic acid, citraconic
acid, mesaconic acid, and Diels Alder adducts of
maleic acid or anhydride with compounds having . .
:
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-- 10 --
conjugated olefinic unsaturation, such adducts being
e~emplified by bicyclo[2.2.1]hept-5-en3-2,3-
dicarboxylic anhydride, methyl maleic acid, and
itaconic acid. Maleic acid or anhydride and fumaric
acid are the most widely used commercially.
E~amples of saturated or aromatic
dicarbo~ycyclic acids or anhydrides which may be
used in the preparation of the polyesters are
materials such as phthalic acid or anhydride,
te~ephthalic acid, tetrahydrophthalic anhydride,
hexahydrophthalic acid or anhydride, adipic acid,
isophthalic acid, sebacic acid, succinic acid, and
dimerized fatty acids.
Polyols useful in the preparation of the
polyesters are materials s~ch as ethylene glycol,
diethylene glycol, triethylene glycol, propylene
glycol, dipropylene glycol, tripropylene glycol,
~utylene glycols, neopentyl glycol, 1,3- and
1,4-butane diols, l,~-pentane diol, 1,6-he~anediol,
glycerol, l,l,l-trimethyl~lpropane, bisphenol A, and
hydrogenated bisphenol A~ It is also possible to
employ the corresponding o~ides, sucb as e~hylene
o~ide and propylene o~ide, etc. Generally no more
than about 20% of the polyols employed in the
preparation of a polyest~r are triols.
In addition to the above esters, one may
also use dicyclopentadiene-modified unsaturated
polyester resins described in V.S. Patents 3,9B6,922
and 3,883,612.
Another type of unsaturated polyester
useful for preparation of polyester-based molding
compositions is the group of materials known as
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~inyl esters. These are reaction products of
saturated polyesters possessing secondary hydroxyl
functionalities with vinyl group-containing acids or
anhydrides such as acrylic acid or methacrylic
acid. An e~ample is the reaction product of an
epo~y resin based on bis-phenol A with an
unsaturated carbo~ylic acid such as methacrylic
acid. Vinyl esters and their preparation are
disclosed in US Patent 3,887,515.
The unsaturated polyester is generally
employed in the composition at a level of between 20
and 5~%, preferably 36% to 4~%, by weight based on
the weight of polyester, monomer, and low profile
additive employed. In practice, it is usually
employed as a 60-65% by weight solution in the
olefinically-unsaturated monomer used for
crosslinking.
The olefinically unsaturated monomer
employed in the molding composition of the invention
is a material which is copolymerizable with the
unsaturated ester to cause ~rosslinking which
effects the curing of the polyester. The monomer
also serves the function of dissolving the
polyester, thereby facilitating its interaction with
the other components of the composition. Sufficient
monomer is employed to provide convenient
processing, but a large e~cess beyond that required
is to be avoided since too much monomer may have an
adverse effect on properties of the final composite
material.
The monomer is generally employed in the
~omposition at a level of between 30 and 70%,
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preferably ~0 to 55%, by weight based on the weight
of polyester, monomer, and any low profile additive
employed.
By far the most commonly employed
olefinically unsaturated monomer is styrene,
although other monomers such as vinyl toluene
isomers, methyl methacrylate, acrylonitrile, and
substituted styrenes like chlorostyrene and
alpha-methyl styrene may also be employed.
Another component of the compositions of
the invention is a thermoplastic low profile
additive, preferably a poly(vinyl acetate).
Suitable ~inyl acetate polymer low profile additives
are poly(vinyl acetate) homopolymers and
thermoplastic copolymers containing at least 50% by
weight of vinyl acetate. Such copolymers include, ~- -
for e~ample, carboxylated vinyl acetat~ polymers
which are copolymers of vinyl acetate and
ethylenically unsaturated carbo~ylic acids such as
acrylic acid, methacrylic acid, maleic acid, fumaric
acid, itaconic acid and the like or anhydrides such
as maleic anhydride; vinyl acetate/vinyl chloride~
maleic acid terpolymer, and the like; ~tc.
Reference is made to US Patents 3,718,714 and
4,284,736, and British Patent 1,361,841 for
descriptions of some suitable vinyl acetate polymer
low profile additives.
The useful ~inyl acetate pol~mer low
profile additivçs ordinarily have molecular weights
within the ran~e from 10,000 to 250,000, prefera~ly
from 25,000 to 175,000. They are usually employed
in the composition at a level of 5 to 25 percent by
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- 13 -
weight, preferably 10 to 20 percent by weight, based
on the total weight of polyester resin, low profile
additive, and monomer.
Other thermoplastic low profile additives
besides poly(vinyl acetate)s should also serve in
the compositions of the invention. E~amples of such
materials are: poly(methyl methacrylate),
polystyrene, polyurethanes, saturated polyesters,
and ground polyethylene powder.
Yet another component of the compositions
of the invention is a reinforcing filler such as
glass fibers or fabrics, carbon fib~rs and fabrics,
asbestos fi~ers ~r fabrics, various organic fibers
and fabrics such as those made of polypropylene,
acrylonitrile/vinyl chloride copolymer, and others
known to the art. Such materials are ~enerally
empl~yed at a level between 5 and 75 % by weight of
the total composition, preferably lS to 50 % by
weight.
Also included in the compositions of the
invention is a blocked polyisocyanate, which is
generally employed at a level of 1-20 parts per
hundred, and preferably 1-10 parts per hundred,
based on the total weight of the resin, the monomer,
and the low profile additive.
A blocked isocyanate i5 an adduct of an
isocyanate and an isocyanate-reactive material, this
adduct bei~g stable at room temperature where
processing takes place, ~ut diss wiating to
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- 14
regenerate the isocyanate functionality at some
temperature above room temperature, usually between
120C and 250~C.
R-N-C~0 > R~N=C~0 ~ R'-H
I I a
R~
. '
The regenerated isocyanate is then free to react
with compounds containing active hydrogen to form .:
more thermally stable units such as urethane
(hydro~yl~isocyanate) or urea (amine+isocyanate) :
linkages.
R - N~CeO ~ Rn_XH > R-N-C=0
l l '
H ~R"
where X - N, 0, or S
:-
E~amples of polyisocyanates which may beused as starting materials for the blocked
isocyanates which are useful in the compositions of
the invention are materials such as tetramethylene
diisocyanate, he~amethylene diisocyanate (HMDI), ~:
1,4-cyclohe~ane diisocyanate, 1,3-cyclohegane
diisocyanate, isophorone diisocyanate (IP~ ylene
diisocyanate, 4,4'-diphenylmethane diisocyanate,
2,4-toluene diisocyanate, 2,6-toluene diisocyanate,
and straight or branched urethane polymers
containing multiple isocyanate substituent groups,
these polymers bDing synthesized from a simple
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polyisocyanate and at least one polyol having at
least two active hydrogen atoms. Examples o~ the
latter materials are isocyanate-containing
prepolymers prepared by reaction of a toluene
diisocyanate (TDI), or a methylenediphenylene
diisocyanate (MDI) or polymeric form thereof
(polymeric MDI), with a polyal~ylene o~ide diol such
as polypropylene o~ide diol. Materials having three
isocyanate groups may also be employed.
- Materials which may be used as blocking
groups are compounds having a single active hydrogen
atom. E~amples of blocking agents for isocyanates
are:
phenols; for example, nonyl phenol,
resorcinol, cresols, and bisphenol A.
imidazoles; for e~ample, imidazole, 1- or
2- methylimidazole, ~-phenylimidazole, 2,~,5-tri-
phenylimidazole, 2,2'-bis(4,5-dimethylimidazole, and
4,5-diphenylimidazole.
pyrazoles; for e~ample, pyrazole,
3-methylpyrazole, 3,~-dimethylpyrazole, and
3,5-pyrazoledicarboxylic acid.
o~imes; for e~ample, 2-butanone oxime,
dimethyl glyo~ime, cyclohexanone oxime,
p-benzo~uinone dioxime, pinonic acid o~ime,
benzophenone o~ime, and 4-biphenylcarbo~aldehyde
o~ime.
materials having acidic hydro~en attached
to carbon, such as acid esters, diketones, and
beta-dicarbonyl compounds generally; for e~ample,
dialkyl malonates, 2,4-pentanedione, and ethyl
acetoacetate. -
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- 16 -
amides; for e~ample, caprolactam.
hydroxamic esters; for e~ample, ben~yl
methacrylohydroxamate (~MH), and acetohydro~amic
acid.
triazoles; for e~ample, ~enzotriazole,
methylbenzotriazole, and 1,2,4-triazole.
alcohols; for e~ample, benzyl alcohol,
ethanol, and butanol.
carbodiimides; for e~ample, carbodiimide
reacts with isocyanate to form uretonimine.
furazon N-oxides; which react by opening
the heterocyclic ring to form isocyanates.
Methods fOI synthesixing blocked
isocyanates are well known to those skilled in the
art. Typically, stoichiometrically equivalent
amounts of the isocyanate compound and the blocking
material are dissolved in separate portions o~ a
suitable solvent, and one is added dropwise to the
other with stirring and heating under an inert
atmosphere. A catalyst may be employed, but is not
always necessary. See, for example, Anagnostou and
Jaul, Journal of Coatings Technology, 53, 35 (1981);
the re~iew articles by Z.W. Wicks in Progress in
Organic Coatings, 9, 3 (1981), and ~, 73 (1975) also
provide references to the original literature.
The dissociation temperature of a blocked
isocyanate is generally a function of the structure
of the blocking group, with alcohols > lactams >
phenols ~ oximes > active methylene compounds.
Aromatic blocked isocyanates usually disso~iate at
lower temperatures than their aliphatic counterparts.
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Blocked isocyanate eompounds have been used
in the coatings and related industries for many
years. However, most blocked isocyanates have been
marketed witb solvents present. These solvent-
containing materials are not suitable for use in the
molding process for fiber reinforced plastic since
this process cannot tolerate the presence of
non reactive solvents.
Blocked iso~yanates apparently have seldom
been employed in polyester-based plastic
compositions. Several references in which they have
been used are discussed below.
U.S. Patent 4,542,177 of Xriek et al.
discloses a thermoplastic polyester molding
composition comprising a blend of a thermoplastic
polyester and a prepolymer derived from reaction of
an organic polyisocyanate with an organic compound
containing at least two isocyanate-reactive groups,
this prepolymer containing blocked isocyanate
~roups. This molding composition is not based on an
unsaturated polyester resin, does not employ an
olefinically unsaturated monomer or a low profile
additive, and does not contain an isocyanate-
reactive material as used in the present invention.
Products produced using this molding composition are
stated to have improved impact performance.
Japanese Kokai Patent No. 57-3Bl9 discloses
a thermosetting polyester resin molding composition
comprising an unsaturated polyester resin and
blocked isocyanate. This molding composition does
not include an isocyanate-reaotive material
different from the unsaturated polyester resin, and
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- 18 -
does not necessarily contain low profile additive or
~einforcing filler. Products made from the molding
composition are stated to have e~cellent strength.
Japanese Kokai Patent No. 56-155216
discloses thermosetting polyester molding
compositions comprising an unsaturated polyester and
a low molecular weight olefinically unsaturated
blocked isocyanate crosslinker. Molded products
made from the composition are stated to have
improved strength.
The isocyanate-reactive materials which are
useful in the thermosetting molding composition of
the invention are materials which contain active
hydrogen atoms, such as polyether polyols, polyester
polyols different from the unsaturated polyester
resin (including those derived from polylactones),
hydro~yl group-containing vinyl polymers,
amine-terminated polyols, diamines, and polyamines.
In these materials primary hydro~yl groups and
primary amino groups are preferred. The
isocyanate-reactive materials are employed at levels
between 1 and 20 parts per hundred, preferably 1 to
10 pph, based on the total weight of the resin, the
monomer, and the low profile additive.
Polyols are the pre~erred isocyanate-
reactive materials. Examples of suitable polyols
are: hydroxyl-containing vinyl based polymers such
as copolymers of Yinyl acetate or other vinyl esters
with hydro~yl cont~ining unsaturated monomers,
terpolymers of ~inyl chloride and vinyl acetate (or
other vinyl esters) with hydro~yl containing
~nsaturated monomers, and also, hydrolyzed versions
.
'
- : .
:,
~?q~ 4~
-- 19 --
of vinyl ester containing polymers; polyester
polyols, diols, and triols, such as DEG/adipate,
ethylene-butylene~adipate, condensation products of
diols with dicarbo~ylic acids having more than 6
carbon atoms, and lactone polyolis such as - -
polycaprolactones; polyether polyols, diols, and
triols, such as polypropylene o~ide and ethylene
o~ide capped PPO (which yields primary hydro~yls); :
and amine-terminated polyols such as amino
terminated polypropylene o~ide or polypropylene
o~ide/polyethylene oxide polyethers.
The molding co~positions of the invention
may also contain one or more conventional additives,
which are employed for their known purposes in the
usual amounts. The following are illustrative of
such additives: -
1. Polymerization initiators such as
t-~utyl hydropero~ide, t-butyl perbenzoate, benzoyl
pero~ide, t-butyl peroctoate, cumene hydropero~ide,
methyl ethyl ketone pero~ide, and others known to
the art, to catalyze the reaction between the
olefinically unsaturated monomer and the
olefinically unsaturated polyester. The
polymerization initiator is employed in a
catalytically e~fective amount, such as from about ~.
0.3 to about 2 to 3 ueight percent, based on the
total weight of the polyester, monomer, and low
profile additive;
2. Fillers such as clay, alumina
trihydrate, silica, calcium carbonate, and others
known to the art;
. :
, i ,. . .. . . .. . . .
3 ~,
3. Mold release agents or lu~ricants,
such as zinc stearate, calcium stearate, and others
known to the art; and
4. Rubbers or elastomers such as: a)
homopolymers or copolymers of conjugated dienes
containing from 4 to 12 carbon atoms per molecule
(such as 1,3-butadiene, isoprene, and the like), the
polymers having a weight average molecular weight of
30,000 to 400,000 or higher, as described in ~S
Patent 4,020,036; b) epihalohydrin homopolymers,
copolymers of two or more epihalohydrin monomers, or
a copolymer of an epihalohydrin monomer(s) with an
o~ide monomer(s) having a number average molecular
weight (Mn) which varies from 8D0 to 50,000 as
described in US Patent 4,101,604; c) chloroprene
polymers including homopolymers of chloroprene and
copolymers of chloroprene with sulfur and/or with at
least one copolymerizable organic monomer wherein
chloroprene constitutes at least 50 weight percent
of the organic monomer make-up of the copolymer, as
described in US Patent 4,161,471; d) hydrocarbon
polymers including ethylene/propylene dipolymers and
copolymers of ethylene/propylene and at least one
nonconjugated diene, such as ethylene/propylene/
he~adiene terpolymers and ethylene/propylene/ : .
1,4-he~adiene/norbornadiene, as described in US
Patent 4,lÇl,971; e) conjugated diene butyl
elastomers, such as copolymers consisting of from 85
to 99.5 percent by weight of a C4-C7 olefin combinPd
with 15 to 0.5 percent by weight of a conjugated
multi-olefin having 4 to 14 carbon atoms, and
copolymers of isobutylene and isoprene where a major
: . : , . ,,: , - . . .. ..
: : . -.: ., : : . , . . - , . .
:. :
3'~
- 21 -
portion of the isoprene units combined therein have
conjugated diene unsaturation, as described in US
Patent 4,160,759.
Thickening agents are also fre~uently
~mployed in the compositions of the invention.
These materials are known in the art, and i~clude
the o~ides and hydro~ides of the metals of Groups I,
II, and III of the Periodic Table. Specific
illustrati~e e~amples of thickening agents include
magnesium oxide, calcium o~ide, zinc oxide, barium
oxide, calcium hydroxide, magnesium hydro~ide, and
mixtures thereof. Thickening agents are normally
employed in proportions of from about 0.1 to about 6
percent by weight, based on the total weight of the
polyester resin, monomer, and low profile additive.
ÇlQssarY of Terms and Definitions of Mate~ials
Alumina Trihydrate a commercially-available
filler.
9MC bulk molding compound.
Camel white Calcium carbonate filler
available from GenStar Stone
Products.
CaSt calcium stearate. -
Desmocap 11~ a branched aromatic urethane
polymer with ether groups,
containing 2.4% blocke~ MCO
content. This i5 a solid
material available from
Mobay Corporation.
' ,
. ~ . : , : ,, . . -. ... . . .
. . .
. . . , - . . i. .. ~ ,. .: . . .
~ .
'~ . ' , . , ' . . .
." ' " ' , ' ' ' ,, . . , ' " . ' ' ~ ' , . ' ' '
' ' ~ ' ', ' ',' . . ' ' ' " ' ~ ' '
.
3'7~
-- 22 --
Desmocap 12a a linear aromatic urethane
polymer with ether groups,
containing 1.7% blocked NCO
content. This is a solid
material available ~rom
Mobay Corporation.
Gamma Plas Calcium carbonate filler
available from Georgia
Marble.
JM 615G 1" fiberglass from Manville
Corp.
LP-40A Acid-modified poly(vinyl
acetate), 40% in styrene.
LPS-40AC Solid acid-modified
poly(vinyl acetate).
MDI methylene diphenylene
diisocyanate.
Microthene Cryogenically ground
polyethylene powder
available from USI, Quantum
Corp.
Millicarb Calcium carbonate filler
from Omya.
Mod E 5% parabenzoquinone solution
in diallyl phthalate.
MR-13017 Isophthalic acid modified
polyester resin available
from Aristech Chemical,
containing about 35 weight
percent styrene.
'
.:
-
. ' : , : ~, , , . , : ~ ' ' ~ 1
"'` ' ~. : '" '~ ' , . ' : ~ "' ', ' : '. i ,
. : . ~
. . .
'~(?A3'il,,,3;~
- 23 -
MR-13031 Orthophthalic acid modified
polyester resin availa~le
from Aristech Chemical,
containing about 35 weight
percent styrene.
Palapreg P-18 Maleic anhydride/propylene
glycol polyester resin
containing about 35 weight
percent styrene and
available from BASF.
pBQ parabenzoguinone.
PDO 50% t-butyl peroctoate
availablQ from Lucidol Corp.
PG-9~33 MgQ (35% dispersion)
available from Plasticolors,
Inc.
PPC-3029 fiberglass reinforcement
(1/2") from PPG Industries.
SMC sheet molding compound.
t9PB t-butyl perbenzoate.
TONE ~301 polycaprolactone triol
available from Union Carbide
Chemicals and Plastics Co,
InC.
Trigono~ 29B7~ a peroxy ketal available
from Akzo Corp.
UCAR~ VYES-4 a terpolymer that contains
appro~imately 29% primary
hydro~yls, available from
Union Carbide Chemicals and
Plastics Co., Inc.
3~ J
- 2~ -
ZMC untnickened injection
molding compound similar to
unthickened BMC, with a
glass content of 20% by
weight.
ZnSt zinc stearate.
XLP-4022 a 37 weight percent acid
modified poly(vinyl acetate)
solution in styrene,
available from Union Carbide
Chemicals and Plastics Co., ~ .
Inc.
,
Experimental
Procedure for Nonyl Phenol Blockina ~ an
~DI Terminated Polyo~YalkYlene Glycol.
Nonyl phenol (I) was obtained as a 99%
mi~ture of monoalkyl phenols. The MDI terminated
polyo2yalkylene glycol (II) was o~tained as a 75%
solution in styrene~ The isocyanate content of (II)
was determined by the method given by Siggia in
~Qua~titative Organic Analysis via Functional
Groups," John Wiley and Sons, 1962, p~59. One mole
of (I) was taken to react with each mole of
isocyanate present in (II). The quantity of (I)
needed to cap all of the isocyanate groups present
in (II), where (II) was MDI terminated
polyoxypropylene glycol, was calculated as shown
below.
g(I~ z g(II) x~g i60cy~nate x 1 ~mole x 220 g~g~l~mol~
100 g(lI~ 42 g 16~cyanate
- . . : . ~ -, , ,
.. , . ~ ~ , . . . . ..
:, ,, , ', . . - , , . ~ ,: . . . .
,
, , , , : . : .
, ~
'~, . ., ,.. , : ,: ~ ., ,. , , ',', ' ' ., :
:,- - - . .. . . . .
-- 25 --
~ecause nonyl phenol is an inhibitor of pero~ide
initiators found in the molding compound (BMC), g(I)
was multiplied by a factor of 0.98 to insure ~o free
nonyl phenol at end o~ reaction.
A weighed amount of (II) was placed ~n a
three neck reactor of appropriate size, then 100 ppm
of parabenzoquinone and 100 ppm of triethylene
diamine were added. The reaction mi~ture was
blanketed by a 4~ oxygen/96% nitrogen mixture, then
heated to 60C under constant agitation, and this
temperature was maintained throughout the reaction.
The phenol SI) was then diluted with styrene to give
a SOD~ solution and added dropwise to the reactor.
Beginning at four hours, specimens ~ere taken for
deter~ination of free isocyanate content as
referenced above. When the free isocyanate content
had dropped to ~0.1~ butanol was added in slight
e~cess to react with any remaining isocyanate. At
0.0% isocyanate the reactor was cooled and dumped.
The product was used as made.
Blocked isocyanates synthesized in this work
are discussed below. Each was composed of MDI, nonyl
phenol (as the blocker), and varied by the molecular
weight of propylene glycol polyol. No free
isocyanate was present due to blocking with nonyl
phenol.
~:xamPle 1
P~eDaratio~ of ~locked Isoc~anate A
Following the procedure gi~en abo~e, a
blocked isocyanate was prepared from a 75% solution
,
:, ,: .- .. .- , , .. .... - . . ,, . . .: " , ,. .. - : . ., ... ., .: .
. ~ ... . , . . . . :. .... , . . ., .. . , ............ .. . : . : . .
' "'',',' ~" .. '. " ' ', '," . ," :, ' ' '''''' '' ', ' ''. ' . ~ ' "' " '~'
.. . ~ , ............. . .. . ............ .. ..
.: : : , . , . , , . , , : ,
~?~ 4~3l t
`
- 26 -
in styrene of an is~cyanate prepolymer based on MDI
and a 2000 molecular weight polypropylene o~ide
diol. The free NCO content of this prepolymer
solution was 2.4 % before blocking.
~am~le 2
PreParation of Blocked Isocyanate B
Following the procedure above a blocked
isocyanate was prepared from a 50% solution in
styrene of an isocyanate prepolymer based on MDI and
a 2000 molecular weight polypropylene o~ide diol.
The free NCO content of this prepolymer solution was
0.5% before blocking.
.
Preparation o~ the Moldina Com ositions
The comp~sitions of the invention are
prepared by mi~ing the components in a suitable
apparatus such as a Hobart mi~er, at temperatures on
the order of about 2~C to about 50C. The
components may be combined in any convenient order.
Generally, it is preferable that the thermosetting
resin and the low profile additive are added in
liquid form by preparing a solution of ~hese
materials in styrene ~r some other liquid
copolymerizerable monomer. All the liquid
components, including the blocked isocyanate and the
isocyanate-reactive material (preferably a primary
polyol), are usually miged together before adding
fillçrs and the thickening agent. Tbe fibergla~s is
added after the thickening agent. Once formulated,
,, ~ , , . . , ~ , , ,::, : ,
- , : :,; -: ,,
:. ....
. ' , . .,: . ,-- , . , ., , , :.
3~11,, 2;~,
- 27 -
the compositions can be molded into thermoset
articles of desired shape, particularly thermoset
articles such as automobile body parts. The actual
moldin~ cycle will depend upon the particular
composition being molded as well as upon the nature
of the cured product desired. Suitable molding
cycles are conducted on the order of about 100C to
about 182C for periods of time ranging from about
0.5 minutes to about 5 minutes. This depends on the
particular pero~ide catalyst employed.
General ReciDe fcr Bulk Moldinq
ComDound (BMC~ Compositions
Material P~W* -
Unsaturated polyester
(60-65 weight % in styrene) 60
. .
Low profile additive
(33-40% in styrene) 40
Recipe for BMC, continued
Blocked isocyanate 1 10
Reactive coupling material
(e.g., polyol) 2-5
Pero~ide catalyst
(t-bu perbenzoate) 1.5
5% pBQ
. ~ - . ., . , .: . , . , . : . , .
';.' ' ." .: , ' .''"''''"' '. "' " ,,.' '",''.'. ..' ~., ' ' ,: .' ' ., ''~, :. ' '
' '': '' , ' '' ' , ' ~: "" ' '' .,, , ' .. , ., .: ,
~ 3'~
- 28 -
Mold release
(zinc stearate) 4
Filler ~calcium carbonate) 230
Fiberglass (as a percentage
of the total composition) 1~.0
weight
percent
Amounts given in parts per hundred, based on the
total weight of the resin, the monomer, and the low
profile additive, except as otherwise noted.
General Procedure for PreParation of Bul~ Moldin~ -
Compound (~MC) Formul-at-iQns
A11 the liquid components were weighed
individually into a Hobart mi~ing pan placed on a
~alance. The pan was attached to a Model C-100
Hobart miser located in a hood. The agitator was
started at slow speed, then increased to ma~imum
speed to completely mix the liquids over a period of
3-5 minutes. The agitator was then stopped and the
internal mold release agent was ne~t added to the
liquid. The mi~er was restarted and the mold
release was mi~ed with the liguid until it was
completely wet out. The filler was negt added to
the pan contents with the agitator off, then mixed
using a medium to high speed until a consi,stent
paste was obtained. The mi~er was again stopped, a
weighed amount of thickening agent was added, and
' .
.. : . . . :. - . - - . , : . :: ::,
-: : .... . ... :.. . - :. : .. , : ,: . - . - : .
: . ,
. .:
' . ' ' ' . . . - . . : . , '' ': ., , '' ' ':
.. , : :. . . ..
: . . ' , , ~, :
. .'': ' : '. '' , . :' ' ' ''
.. . . .. . . . . .
- 29 -
then this was mi~ed into the paste using a slow to
medium speed over a period of ~-3 minutes. The
mi~er was stopped again and about 175 grams of the
paste were removed from the pan using a large
spatula, and transferred to a wide-mouth ~ oz
bottle. The bottle was capped, and the paste sample
was stored in the capped bottle at room temperature
and viscosity was measured periodically using a
model HBT 5X Brookfield Synchro-Lectric Viscometer
on a Helipath.
After removal of the paste sample, the
composition was reweighed and styrene loss was made
~p, and chopped glass fibers were added slowly to
the pan with the mi~er running on slow speed. The
mixer was then run for about 30 seconds after all
the glass was in the paste. This short mixing time
gave glass wet-out without degradation of the
glass. The pan was then removed from the mi~er and
separate portions of the BMC mix of about 1200 grams
each were removed using a spatula and were
transferred to aluminum foil sheets lying on a
balance pan. Each portion of the mix was tightly
wrapped in the aluminum foil (to prevent loss of
styrene via evaporation) and stored at room
temperature until the viscosity of the retained
paste sample reached an appropriate molding
viscosity. The weight of the BMC added to the foil
varies with the molding application.
. .
', ', .,'; ,'
.
- , , : ,' ~ , ' ' ' ', ,
" ,.,.. ,." " ,.. ; , ...
General ~ecipe ~or Shee~ Moldina
Com~ound (SMG~ Com~o~itions
Material
Unsaturated Polyester
(60% in Styrene) 60
Low profile Additive
(33-40~ in Styrene) 40
Filler ~Calcium Carbonate)
(3-5 micron particle size) 150 70-75%
Pero~ide Catalyst
~t-Bu perbenzoate) 1.5
Mold release
~zinc stearate) 4
Thickener
(MgO) .~-1 J
(as needed)
Chopped glass fiber (one inch) } 30-25%
x Amounts giYen in parts per hundred, based on the
total weight of the resin, the monomer, and the low
profile additive. Numbers in the right-hand column
refer to the respective percentages of the
composition and glass.
~e~eral Procedure for Preparation of Sheet Moldina
ComPound (SMC) Formulations -
~' :
All the liquid components were weighed
individually into a five gallon open top container
on a Toledo balance. The contents of the container
were then mixed in a hood with a high speed Cowle~
type dissolver. ~he agitator was started ~t a slow
speed, then increased to ma~imum speed to completely
,: ' . . ' , ' ', ' ' ': ' ' ' . '
~ :- . . , .: . : . :
:, - ~ - . ' , .~ ~.:,
7~,l;,3~,
-- 31 --
mi~ the liquids over a period of 2-3 minutes. The
mold release agent, if one is desired, was ne~t
added to the liquids and mi~ed until completely
dispersed. The filler was next added gradually from
a tared container until a consistent paste was
obtained, and the contents were further mi~ed to a
minimum temperature of 90~F. The thickener, if
used, was ne~t mi~ed into the paste over a period of
2-3 minutes, the mi~er was stopped and about 175
grams of paste were removed from the container and
transferred to a wide mouth 4 oz bottle. This paste
sample was stored in the capped bottle at room
temperature and its viscosity was measured
periodically using a model ~BT 5X Brookfield
Synchro-Letric Viscometer on a Helopath Stand. The
remainder of the paste was ne~t added to the doctor
~o~es on the SMC machine where it was further
combined with fiber glass ~about 1 inch fibers).
The sheet molding compound (SMC) was then allowed to
mature to molding viscosity and was then molded into :
the desired articles.
Apparatus and Process for Preparation
of Moldinq Test Panels
Flat panels for surface evaluation were
molded on a 200 ton Lawton press containing a
matched dye set of lBn~18" chrome plated molds. The
female cavity is installed in the bottom and the
male portion is at the top. Both molds are l~
electrically heated and are controlled on separate
circuits 50 that they can be operated at different
' '- ' : ~ .. ' ' . :,'. ~ .. ' ,...... .
.:, .';. : , . . -
. ': '' ',: .: :. .. : . :: ' .. . : .
. , , , , . ", . , . :
-- ~ . . : ::,., : , ,
, ~ : ~ , ' , : , . .
-: :' : :, , : ,
.
,
- 32 -
temperatures. For the present molding, the top and
bottom temperatures were 295-305 F, 12009 samples
of molding compound were employed, and the molded
part thickness was 0.12~". The molding pressure,
which can be varied from 0 to 1000 psi, was run at
magimum pressure. The panels were laid on a flat
surface, weighted to keep them flat, and allowed to
cool overnight. The molded panels were measured
with a micro caliper from corner to corner in all
four directions to determine shrinkage, which is an
average of the four readings. These panels were
used for surface smoothness determinations.
Sh~inkaae Meas~remen~
18"x18"xl/8" flat panels were molded in a
highly polished chrome plated matched metal die mold
in a 200 ton Lawton press, as described above. The
e~act dimensions of the four sides of this mold were
measured to ten-thousandths of an inch accuracy, at
room temperature. The exact lengths of the four
sides of the flat molded panels were determined to
the same degree of accuracy. These measurements
were substituted into the equation below:
(a-b)/a ~ inch~inch shrinkage
where a , the sum of the lengths of the four sides
of the mold, and b = the sum of the lengths of the
four sides of the molded panels.
,. . , . , . :
- . - ,. .
-:
,, : ,,: . . .. . ~ . . :
.'. , , . ,' ' , . ~
>~ ?
- - 33 -
The shrink control test compares the
perimeter of a cold panel to the perimeter of the
cold mold. A positive number indicates an e~pansion
and vice-versa for a negative number as compared to
the cold mold. The units mil/inch indicate the
amount of e~pansion (~) or contraction (-) in mils
per inch of laminate (or panel perimeter).
Evaluation of Surface Smoothn~ss
- The faithful reproduction of a reflection
of a light grid's 1" ~ 1~' squares on the surface of
a molded panel gave a visual picture of the surface
smoothness. A quantitati~e evaluation of surface
quality was obtained by comparing two panels
simultaneously and picking the panel with the best
reproduction of the reflected squares. This
technique was repeated until the surface of every
panel in the series was compared to all other
panels. Surface smoothness was measured as a
frequency, or number of times that a panel was
picked as being the best in surface quality.
Therefore, the highest number denotes the best
panel; the lowest number, the worst panel.
BMC RESULTS
Bulk molding compositions were prepared with
and without Desmocap llA to test the effects of the
presence of a blocked polyisocyanate in such
compositions. The ingredients and their amounts are
listed in Table I below.
- . . .
- . . ...
. : ., ; : . .. . .
. , ~ , . - ,. . . . .
.
. . , , ~ ' : .
-- 39 --
Table I
Effect of Blocked Is~cYanate
in B~lk Moldina Com~sitions
Component E~mPle Numbe~s
#3 #4
Palapreg P-18 53 ~3
LP-40A 42 41
Desmocap 11~ x
Styrene 5 5
tBPB 1.5 1.5
PDO 0.25 0.25
Mod E 0.~ 0.4
Ca St 2 2
Zn St 2 2
Camel white 230 230
PPG-3029 fiberglass, 20% by wt. in each composition
Fle~ural Properties: #3 #4
Fle~ Modulus (mpsi) 2.02 1.99
Fle~ Strength (psi) 12760 15200
Est. Energy at Break (in-lbs) 3.2 4.5 ~ .
* Amounts given in parts per hundred, based on the -~
total weight of the resin, the monomer, and the low
profile additive, escept as otherwise noted.
The results shown in Table I demonstrate
that a block~d polyisocyanate can lead to an increase
in fle~ural properties of the resulting composite
relative to the composite lacking this additive. The ; .
~ontrol formula, E~ample #3, gives a laminate about
20% lower in fleg strength and about 40% lower in
break energy than the material containing blocked
isocyanate, Example #4. The greater increase in .
break versus fle~ strength reveals that E~ample #4
not only achieves higher loads but also a greater
.. , : ,: . . . , . . :~
, , , , ~, , , : :,
, . : . ~ . . , - . : . .
,. ~ .
;~q`~ ;3
-- 35 --
amount of deflection before failure. Furthermore
this improvement was obtained at the relatively low
level of 1 phr of additive.
Additional e~perimental bulk molding
compositions were prepared, in which the amounts of
the blocked polyisocyanate and styrene monomer were
varied, and in one of these trials (E~ample #8) the
additional reactive polyol UCAR VYES-4 was included.
The compositional makeup and test results relating to
th~se composites are shown in Table II below.
. ! : ,
' ' ' '' , ''''''' . ' ' ' : ' ' ' ,. . ,, ,''' . ' ' :
~, . ' , . ' , , , . ' ' '
',. ' ' '. ' ' . ,. ' ' . .' '' ' ' ~ ' ,' .
. .
, ' '
~`3'~67~3
T~BLE II
BlDcked I60cyanate Effect6
Component Example N~mbers
1~5 #6 #7 #8 #9
NR-13031 53 53 53 53 53
LP-40A 42.3 42.3 42.3 42.3 42.3
Desmocap llA x 1.4 2.8 1.~ x
Styrene 4.7 3.3 1.9 0.9 4.7
Table II, continued
~CAR VYES-4 x x x 2.4a x
tBPB 1.5 1.5 1.5 1.5 1.5
PD~ ~.25 0.25 0.25 0.25 0.25
C~ S~ 2 2 2 2 2
Zn St 2 2 2 2 2
Millicarb 230 230 230 230 230
~PG-3029 fibergla~s 20% by wt.
.
Flexural Properties: #5 ~6 ~7 ~ ~9
Flex ~odulus ~mpsi) 2.38 2.51 2.35 2.532.32
Flex Strength (psi) 12960 16280 163701860011510
Est. En~rgy at Break (in-lbs~ 2.8 3.7 4.3 4.2 2.1
Surface Properties: ~5 #6 ~7 ~8 #9
Surface Smoothne~s (freq) 11 9 12 17 7
Shr~nk Control (mil/in) -0.041 0.1660.2220.166 0.027
* Amount~ en in parts per hundred, based on the toSal weight of
the re~in, the monomer, and the low profile additive1 eacept as
otherwi6e ~oted.
a) Thi~ material W~8 predissol~ed in the LP-40A before add;tion to
the formulation.
: .
"
.. . .: . - .. - . . . . . . . . . .
~: - . . . . ; .. , , :
: : . . : .. . . :: , , ,,, . .. . ,.. . , :..... .
: . , - ,: . ,
, . .. . , : : - . ,: . .: : . :.. . ~: :.. :
. - , . . . - . :. : .
: . . . ~ .: :: ..
, , :. . , . ' . .: , . . :' . : , : ' ' :,' ' : , :
- 37 -
The results shown in Table II are further
evidence that a blocked polyisocyanate provides
increased fle~ural strength and break energy. The
control materials #~ and ~9 containing no blocked
polyisocyanate were appro~imately 33% lower in
strength and about 60% lower in break energy than
test composites #6 and #7, which contained blocked
polyisocyanate. Again, these results were achieved
at relatively low levels of blocked polyisocyanate.
E~ample #8, which contained reactive polyol UCAR
VYES-4 in addition to blocked polyisocyanate,
exhibited an increase in flex strength over the
composites of trials #6 and #7. -
Table II also includes an evaluation of the
surface properties, surface smoothness, and shrink
control of the test composites. The blocked
polyisocyanate provided a minor but positive
contribution to shrink control. More noticeably, the
addition of reactive polyol UCAR~ VYES-4 in E~ample
#8 substantially improves the surface quality of the
composite.
Several test compositions based on a ZMC
formulation were prepared, each containing one of two
blocked polyisocyanates, and three containing an
additional reactive polyol. The styrene level was
also varied. These compositions and amounts of
ingredients are listed in Table III below.
, . , - - . . ~ ~ :
:, . ~ ... .
, . , .. , . -
.
:: . , ... -, : . . . ~ . - .
, -, : . . . . .
- ~ . , . . :, .
,, , , , :
; " . ', , ' , '' ' . . . '
- . ' ' ,
3 7,,~t~
-- 38 --
TABLE III
Bloeked Isocyanates with Various Polyols
Component . Exam~le N~mbers _ _
#10 #11 ~12 ~13 #14
~R-13û31 53 53 53 53 53
Table III, cont;nued
LP-4ûA 42.3 42.3 42.3 42.3 42.3
- Desmocap llA 2.35 x 2.35 2.35 x
Desmocap 12A x Z.35 x x x
UCAR VYES_4a x x Z.35 x x .
TONE 03ûl x x x 2.35 x
Styrene 2.35 2.35 x x 4.7
tBPB 1.5 1.5 1.5 1.5 1.5
PDO û.25 û.25 û.25 0.25 0.25
Mod E û.4 0.4 0.4 û.4 0.4
Ca St 2 2 2 2 2
Zn St 2 2 2 2 2
Millicarb 23û 230 23û 230 23û
PPG-3029 ~;berglas 20'~ by we;ght in all samples
Flexural Properties: #10 ~Ll #12_~L~ #14
Flex Modulus (mpsi) 1.85 1.83 1.921.54 1.~
Flex Strength (ps~) 10850 17340 1715014420 1126Q .
~st. Energy at Break
(in-lbs) 2.9 6.5 6.5 5.4 3.4
: .
Flex Prop., postbakùd: _l~lQ 3~Ll #12#13 ~14
Flex M~dulus (mpsi) 1.78 2.1 1.891.72 1.89 : .:
Flsx Strength ~psi) 11150 17000 1693û14420 1138û
st. Energy at Break
(in-lbs) 3.1 6.2 6.1 5.7 3.2
. . .'' ' ' -', : ' "' - "' " ' " .' ' " ''' " ' , . ' ~ ~, ' ." '. :' ..
' ' ' ' .', ' '"' ' ' : - , . " , ', ' : ', ' ' ' ' , ' ' , '
' ~ ' ... ' .' ~ ,. ., , ''. ' . ' , ',,; " .' ' :
~,~3~ 3~,
- 39 -
Table III, c~ntinued
5urface Pr~perties: #10 #11 #12 ~13 ~14
Surface Smoothness 10 15 22 27 9
(freq.)
Shrink Control (mil/in) û.263 0.361 0.333 0.374 û.182
~ Amounts given in parts per hundred, based on the total weight of the
resin, the monomer, and the low profile additive, except as otherwise
noted.
a) This Dateria~ w~s prediss~lved in the LP-4ûA before introducti~n ;nto
the fon~ulati~n.
In Table III the blocked polyisocyanates
Desmocap llA and 12A were evaluated in a polyester
resin based ZMC formulation with respect to surface
guality, shrink control, and flex properties.
~esmocap llA was also compounded with polyisocyanate
reactive polyols such as UCAR~ VYES-4 and TONE ~301.
The control formulation contained LP-40A.
In the surface quality evaluation virtually
all sf the compositions containing blocked
polyisocyanate outperformed the control composition
lacking these additives. Further~ the panels that
contained ~he reactive polyols UCAR~ VYES-4 and TONE
D301 had shrink control values >~0.300 and had
egcellent surface guality with good gloss. These
were the best panels of the surface quality ~ -
evaluation.
: In the fle~ property evaluation study, the
control laminate #14, containing only LP-40A,
... . . . . . . . .. . .
.. . ~. . . . . , , , : , , , :
- . . ~ . . :
.:: , , ` : , .. . :' ` ' . l -... . .. ... . .. . .. .
~g~ ;}~3
attained slightly higher than typical ~MC fle~
strength of approximately 11,000 psi and an energy to
break of about 3.4 in-lb. Composition #12,
containing both Desmocap llA and the polyol coupling
agent VCAR~ V~ES-g, had the highest fle~ strength and
break energy of all the compositions containing
Desmocap 11~, namely, 17,150 psi and 6.5 in-lb,
respectively. ~owever, in composition #10, Desmocap
llA alone failed to confirm previous results of a
significant increase in flex properties, showing a
fle~ strength of 10,850 p5i and an energy at break of
2.9 in-lb. It appears that to obtain a consistent
increase in flex performance from a blocked
polyisocyanate the addition of a reactive polyol such
as the ~CAR~ VYES-4 is required.
To ascertain if there was any residual
unreacted polyisocyanate in these laminates they were
postbaked at 300F for 20 minutes. Comparing the
fle~ results of baked versus unbaked laminates, it
can be seen that there is ~ery little difference
between the two. Therefore, it would appear that
most of the blocked polyisocyanate is reacted during
the molding step.
Further trial compositions to evaluate the
effects of other blocked polyisocyanates in the
presence of the primary polyol UCAR~ YVES-4 were
prepared in the same manner as those discussed
abo~e. The inyredients and their amounts are listed
in Table IV below.
-, , . , , , . . . , . :. : . , , ,, . :. . .:
,: . , :
. . ; , ~. ..
;~C`~ '7~'31 ~
91
TABLE ~V
Blocked Isocyanates ~ith a Primary Polyol
Component Example N~mbers
#1~ #16 ~17 #18 #19 #20 ~21 ~22 #23
MR-13031 J3 83 53 53 53 ~3 ~3 53 53
LPS-40ACa 16.8 16.816.8 16.8 16.8 16.8 16.816.8 16.8
UCAR W ES-4a 2.3 2.3 2.3 2.3 2.3 2.3 x 2.33 2.3
Styrenea 23.2 23.223.2 25.6 25.6 25.6 30.227.9 27.9
Blocked isocyanate A 4.7 x x 2.3 x x x x x
Ulocked isocyanate ~ x 4.7 x x 2.3 x x x
Desmocap 12A x x 4.7 x x 2.3 x x x
tbPB 1.~ 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5
PD0 0.25 0.250.25 D.25 0.25 0.25 0.250.25 0.25
Ca St 2 2 2 2 2 2 2 2 2
Zn St 2 2 2 2 2 2 2 2 2
~illicarb 230 230 Z3D 230 230 230 230 230 230
PPG-3029 fiberglass 20% by weight ;n each sample.
Flexural Propert;es: #15 #16 #17 #1~ #19 ~2Q #21 #22 ~_
Flex HDdulus (mps;) 2.8 2.1 1.78 2.05 1.97 1.96 2.1 2.1 1.85
Flex Strength (ps;) 174201790013185185702014516~30 14580 12180 11180
Est. ~nergy at Break
(in-lbs.) 6.9 7.2 5.1 B.l 9.4 6.7 4.5 3.3 3.2
Impact Propert;esi #15 ~ #17 #18 #19 #20 ~21 #22 #23
Unnotched I~od
(in-lb/;n) 10.2 10.5 9.1 lZ 12.2 13.1 8.6 7 9
Notched Izod (in-lb/in) 8.9 10.3 7.3 8.7 7.4 B.8 8.6 7.22 lû.2
Surface Properties #15 #16 #17 i la #19 ~Q #21 #22 #23
Surface SmDothness
tfreq.) 6 10 12 16 18 12 12 x x
Shrink Control ~m;l/in) 0.337 0.324 0.445 0.311 0.351 0.405 0.202 0.324 0.216
Amounts given ;n parts per hundred, based on the total weight of the res;n, the
~onomer, and the low profile add;t;ve, except as otherwise noted.
a) The LPS-40AC, UCAR VES-4, and styrene were predissolved together before
introduction to the formulation.
:
:,
' , ', , ' , " '
,, . : ' .,
,. . . i ~ '
' '
~ 3'~
These e~periments indicate that the
synthesized blocked isocyanates perform well when
combined with the reactive polyol. The reacti~e
polyol without blocked isocyanate yields poor results.
A sheet molding formulation was made up with
and without the blocked polyisocyanate Desmocap 12A
and polyol UCAR~ VYES-4 in the manner descri~ed
above, to test the effects of these additives in
sheet molding compositions. The ingredients and
amounts are given in Table V below.
TABLE V
Corroborating Evidence in SMC
E~ample Numbers
#24 ~25
MR-13017 ~3.9 63.9
LP-40A 32~5 36.1
UCAR VYES-4a l.B ~ -
Desmocap 12A l.B x
Styrene 5 5
Trigono~ ~9B75 1.1 1.1
Mod E 0.3 0.3
Microthene 4 4 - ::
Zn St 5.6 5.6
Pigment 19.1 14.1
Alumina Trihydrate 33.3 33.3
5amma Plas 133.3 133.3
JM 615G, 1" fiberglass 14% by wt. 14% by wt.
PG-9033 1.5 1.5
Fle~ural Properties: #24. ~
Fle~ Modulus (mpsi) 1.53 1.35
Fle~ Modulus (psi) 17950 11300 - .
Est. Energy at Break
(in-lbs) . 10.2 5.7
Impact Properties: #Z4 ~25
Notched Izod 10.6 7.6
Vnnotched Izod 10.8 9
* AmouDts given in parts per hundred, based on the
.
. . . . ..
' . ': ' ,' .. ' ', . ' '' . ' . '',, :
. . . .
. . -. : . . - : : . . : . .
, ~. , . , . ,:
,- : ,, . ' ,. ' : .' : .,~ ., :.
, . . . .
- ~3 -
total weight of the resin, the monomer, and the low
profile additive, e~cept as otherwise noted.
a) This material was predissolved in the LP-40A
before intro~uction into the formulation.
Table v shows the increase in physical
properties in sheet molding compound as a result of
adding a blocked polyisocyanate and additional polyol
to the formulation. Increases of appro~imately 55%
and 75% are seen in flex strength and break energy,
respectively, over the LP-40A control. Izod impact
results, though not as dramatic, are also higher than
the control.
Other embodiments o~ the invention will be
apparent to the skilled in the art from a
consideration of this specification or practice of
the invention disclosed herein. It is intended that
the specification and examples be considered as
egemplary only, with the true scope and spirit of the
invention being indicated by the following claims.
-
- .
: .. . .
.
.
