Note: Descriptions are shown in the official language in which they were submitted.
21 1 l 53l
FIELD OF I~V~N-lION
This invention relates to a toughened
thermosetting in-mold coating composition useful for in-
mold coating a molded fiber reinforced thermoset plastic
such as a fiberglass reinforced polyester resin (FRP)
molding or part.
BACKGROUN~ OF THE I~v~NllON
A major deficiency of compression molded
thermoset glass fiber reinforced polyester (FRP)
moldings is surface imperfections such as pits, pores,
surface cracks, waviness, and sink marks. Another
deficiency is surface cracks that can develop at low
hen~; ng strains.
U.S. Patent 4,515,710 describes an in-mold
coating composition that is free radically cured to
create a thermoset coating having good adhesion to the
thermoset substrate, good surface smoothness, and good
paintability.
U.S. Patent 4,242,415 describes another in-
mold coating composition containing amine-terminated
reactive liquid polymers, a vinyl monomer, and
crosslinkable ester urethane resins.
It is the object of this invention to provide
a vinyl ester resin composition with telechelic flexible
,~1".,,
_ - 2 ~ 2 L11531
polymers or AB, ABA, or A(BA)n block copolymers having
flexible segments (B). These compositions with flexible
segments have greater strain to failure and thus
maintain good surface quality after deformation of the
coated part.
SUMMARY OF THE INVENTION
According to the present invention, an in-mold
coating composition comprising a vinyl ester resin,
ethylenically unsaturated monomers, low profile
additives, carbon black, and free radical initiators is
modified with telechelic flexible polymers or ABA-type
block copolymers where B is a flexible polymer segment.
These modifiers give the in-mold coating greater strain
to failure, which means the coating is more durable
during processing of the part, and in later
applications, of the molded part.
The particular ABA block copolymers useful for
this invention are described in the "Detailed
Description" while the incorporation of the ABA and/or
telechelic polymers is described in the "Further
Embodiments of the Detailed Description."
DETAILED DESCRIPTION OF THE BLOCK COPOLYMERS
The B portion of the block copolymers of the
present invention can generally be any flexible polymer.
Such flexible polymers are generally defined as any
polymer which has a Tg of about 0C or less and prefera-
bly below minus 20C, often are liquid, and are readily
known in the art and to the literature, including the
preparation thereof.
One such class of flexible polymers is the
various conjugated dienes made from one or more monomers
having from 4 to 12 carbon atoms, desirably from 4 to 8
carbon atoms with 4 or 5 carbon atoms being preferred.
Examples of specific dienes include butadiene, isoprene,
2,3-dimethyl-1,3-butadiene, pentadiene, hexadiene, 4,5-
~ ~ 3 ~ ~111531
diethyl-1,3-octadiene, and the like, with butadiene and
isoprene being preferred. The structure of such conju-
gated dienes is generally such that it has a Tg within
the above-noted ranges. Such polymers are terminated
with either one or two functional end groups wherein the
functional end group is hydroxyl, amine, or carboxyl.
Thus, the B block can be a mono- or di- hydroxyl termi-
nated flexible polymer, a mono or diamine terminated
flexible polymer, or a mono- or di- carboxyl terminated
flexible polymer. Such polymers are well-known to the
art and are commercially available as from the BFGood-
rich Chemical Co., under the Hycar~ trademark.
Another class of the B block flexible polymer
is the various hydrogenated dienes or polyolefins which
are mono or di-hydroxyl, carboxyl, or amine terminated.
Such polymers, as well as the preparation thereof, are
well known to the art and to the literature. Typical
diene polymers are made from one or more conjugated
dienes, having from 4 to 10 carbon atoms, such as 1,3-
butadiene, isoprene, dimethyl butadiene, and the like.The polymerization of the diene monomer, typically, may
be done via anionic initiation (e.g. with di-lithium
hydrocarbyl initiators) or via free-radical polymeriza-
tion, e.g. by initiation with hydrogen peroxide, which
also introduces hydroxy end groups. In case of anionic
polymerization, OH-end groups are advantageously intro-
duced by reaction of the polymeric carbanion chain ends
with ethylene oxide. These techniques are generally
well known to the literature. The hydroxy-functional
polydienes may be hydrogenated, for example, partially
or substantially (i.e., at least 50, 70, or 90 percent
of the unsaturated sites), and even completely hydroge-
nated, according to any conventional method known to the
art and to the literature. Complete hydrogenation of
various diene polymers such as 1,4-polyisoprene is
equivalent to an alternating ethylene/ propylene hydro-
carbon polymer. The hydrocarbon polymers generally have
- 2 1 1 1 53 1
- 4 -
a number average molecular weight from about 500 to
15,000 and preferably from about 1,000 to about 8,000.
The polymers are desirably liquid at room temperature,
but can have a melting point up to about 80C. Pre-
ferred polymers are hydroxyl functional telechelic,
hydrogenated diene polymers containing 2 to 6 and
preferably 2 to 4 hydroxy end ~LOups per polymeric
molecule (polymer unit).
The hydroxyl, carboxylic or amine terminated
polyolefins are generally made from one or more olefins
having from 2 to 6 carbon atoms such as ethylene,
propylene, butylene, and the like. Such functional
polyolefins can also be made by utilizing minor amounts
(i.e., up to about 50 mole percent and preferably up to
20 mole percent) of ethylenically unsaturated comonomers
such as styrene, vinyl toluene, alpha-methylstyrene,
divinylbenzene, and similar aromatic monomera; or vinyl
monomers, such as acrylonitrile, methacrylonitrile,
vinylidene chloride, and similar aliphatic vinyl mono-
mers; or hydroxyl functional ethylenically unsaturated
monomers such as 2-hydroxyl ethyl acrylate and meth-
acrylate, 2-hydroxy propyl acrylate and methacrylate and
similar hydroxy alkyl acrylates. Regardless of the type
of polyolefin, it should contain either one or two
hy~o~yl groups per average molecule.
An especially preferred hydrogenated butadiene
polymer is commercially available as Polytail ~ and
Polytail HA sold by Mitsubishi Kasei Corp., and has the
very generalized structure:
HO--~--CH2 ICH--t--x--~--CH2--CH2--CH2--CH2 ) y OH
CH2--CH3
wherein 1,2-butylene (x) and 1,4-butylene (y) segments
are randomly distributed and the structure can contain
additional -OH groups.
Still another class of the B block flexible
-~ - polymer i5 the various mono- or di- hydroxyl, amine, or
~ carboxyl terminated nitrile containing copolymers.
211153~
These copolymers are prepared in accordance with conven-
tional techniques well known to the art and to the
literature and are generally made from one or more
monomers of acrylonitrile or an alkyl derivative thereof
with one or more conjugated dienes and optionally one or
more monomers of acrylic acid, or an ester thereof.
Examples of acrylonitrile monomers or alkyl derivatives
thereof include acrylonitrile and alkyl derivatives
thereof having from 1 to 4 carbon atoms such as meth-
acrylonitrile, and the like. The amount of the acrylo-
nitrile or alkyl derivative monomer is from about 1
percent to about 50 percent by weight and preferably
from about 5 percent to about 35 percent by weight based
upon the total weight of the nitrile containing copoly-
mer.
The conjugated diene monomers generally have
from 4 to 10 carbon atoms with from 4 to 6 carbon atoms
being preferred. Examples of specific conjugated diene
monomers include butadiene, isoprene, hexadiene, and the
like. The amount of such conjugated dienes is generally
from about 50 percent to about 99 percent by weight and
preferably from about 55 percent to about 75 percent by
weight based upon the total weight of the nitrile rubber
forming monomers. Such mono or difunctional nitrile
rubbers can be readily prepared generally containing
either hydroxyl or carboxyl end groups and are known to
the art and to the literature and are commercially
available such as from The BFGoodrich Company under the
tradename Hycar~.
Yet another class of the B block flexible
polymers is the various copolymers made from vinyl
substituted aromatics having from 8 to 12 carbon atoms
and conjugated diene monomers generally having from 4 to
12 carbon atoms, desirably from 4 to 8 carbon atoms, and
preferably 4 or 5 carbon atoms. Examples of suitable
aromatic monomers include styrene, alphamethyl styrene,
and the like, with specific examples of conjugated
2 1 1 1 53 1
dienes including hexadiene, isoprene, butadiene, and the
like. A preferred copolymer is a random styrene butadi-
ene copolymer. The amount of the vinyl substituted
aromatic component, such as styrene, is generally from
about one part to about 50 parts, and desirably from
about 1 part to about 30 parts by weight, based upon the
total weight of the copolymer. The preparation of such
polymers having mono or di- hydroxyl, amine, or carboxyl
terminated vinyl substituted aromatic conjugated diene
copolymer are well known to the art and to the litera-
ture.
A still further class of the B block flexible
polymers is the various polyethers which are either
mono- or di- hydroxyl, amine, or carboxyl terminated.
Such polyether polyols are generally made by reacting
one or more alkylene oxides having from 2 to 10 carbon
atoms such as propylene oxide with a strong base such as
potassium hydroxide, preferably in the presence of
water, glycols and so forth. Polyether polyols can also
be made by ring opening polymerization of tetrahydrofur-
an or epichlorohydrin using acid catalysts. Examples of
polyethers which can be utilized are those which are
produced as by polymerization of tetrahydrofuran or
epoxides (such as ethylene oxide, propylene oxide,
butylene oxide, styrene oxide, or epichlorohydrin), or
by addition of epoxide compounds (preferably ethylene
oxide or propylene oxide), alone, in a mixture, or in
sl~ccession, to starting components with reactive hydro-
gen atoms such as water, polyhydric alcohols, ammonia,
or polyfunctional amines. The above mono- or di-
hydroxyl, amine, or carboxyl terminated polyethers, as
well as the preparation thereof, are well known to the
art and are commercially available. Hydroxy terminated
polytetrahydrofurans are commercially available as from
DuPont as Terethane. Hydroxy terminated polypropylene
oxides are commercially available as from Dow Chemical
TM
~ as Voranol and amine terminated polyethers are commer-
21 1 1 531
cially available as from Texaco as Jeffamine~
The polyester or A block is generally an
unsaturated polyester having an average molecular weight
of between 100 or 500 to 2,000 or 5,000 and has one, or
less desirably two, functional end groups thereon such
as hydroxyl, carboxyl, or amine The polyesters are
made by the copolymerization of generally cyclic ethers
typically containing 2 or 3 carbon atoms in the ring and
an unsaturated anhydride, as well as optional saturated
anhydrides using double metal complex cyanide catalysts
Generally any cyclic oxide can be utilized such as 1,2-
epoxides, oxetanes, and the like, with the cyclic ether
having a total of up to 18 carbon atoms, as for example
2 carbon atoms in the ring and up to 16 carbon atoms in
the side chains Such cyclic oxide monomers can also
contain one or more aliphatic double bonds and prefera-
bly only contain one aliphatic carbon to carbon doubl~
bond Examples of suitable cyclic oxides includ-
ethylene oxide (1,2-epoxy ethane), 1,2-propylene oxide,
1,2-butene oxide, 1,2-hexene oxide, 1,2-dodecane monox-
ide, isobutylene oxide, styrene oxide, 1,2-penten-
oxide, isopentene oxide, 1,2-heptene oxide, allyl
gylcidyl ether, isoheptene oxide, 1,2-octene oxid-,
methyl glycidyl ether, ethyl glycidyl ether, phenyl
glycidyl ether, butadiene monoxide, isoprene monoxid-,
styrene oxide, tolyl glycidyl ether, 1,2-pentadecen-
oxide,epichlorohydrin,glycidoxypropyltrimethoxysilan-,
and the like Generally, ethylene oxide, propylen-
oxide, and butylene oxide are preferred
Generally five-member cyclic anhydrides ar-
preferred, especially those having a molecular weig~t
between 98 and 400 Mixed anhydrides as well as mix-
tures of anhydrides may be used Examples of preferr-d
anhydrides include those of maleic, phthalic, itaconic,
nadic, methyl nadic, hexahydrophthalic, succinic,
tetrahydrophthalic, 1,2-naphthalenedicarboxylic, 1,2-
-~ tetrahydronaphthalene dicarboxylic acids, and the lik-
2 1 1 1 53 1
-- 8
Further examples include such anhydrides in which hydrogen
atoms have been substituted by halogen, hydroxyl or C18
carbon atom alkyl, aryl or aralkyl groups such as the
anhydrides of 3,4-dichlorophthalic, hexachlorodicyclo-
heptadiene dicarboxylic (chlorendic), 8-hydroxyl-1,2-
naphthalenedicarboxylic, 2,3-dimethyl maleic, 2-octyl-3-
ethyl maleic, 4,5-dimethyl phthalic, 2-phenyl-ethyl
maleic, 2-tolyl maleic and the like.
As noted above, mixtures of saturated and unsaturated
anhydrides can be utilized with generally maleic anhydride
being preferred. Such polyesters are known to the art and
to the literature and are generally made utilizing double
metal cyanide complex catalysts. The method, preparation
and scope of the various types of unsaturated polyesters
which are suitable in the present invention are described
in U.S. Patent No. 3,538,043. For example, suitable
catalysts for preparation of the polyester A block include
zinchexacyanocobaltate and analogs thereof as well as
various metalloporphyrins. Reaction temperatures
generally include ambient to about 130C with from about
40 to about 80C being preferred. Such polyesters if made
by utilizing maleic acid, can be isomerized with various
conventional amines such as morpholine or piperidine to
produce the fumarate isomer, as taught in U.S. Patent No.
3,576,909, to Schmidle and Schmucker, which is hereby
fully incorporated by reference with regard to all aspects
thereof. Hydroxyl or carboxyl end groups are readily
obtained by simply utilizing either an excess of the
glycol or of the acid. Amine groups are added generally
by post-reaction with an amine compound such as ethylene
diamine, and the like. Such aspects are of course well
known to the art and to the literature. Generally, such
polyester A blocks have a significant molecular weight, as
above 500. A preferred ester of the present invention is
.; ~,
3 1
g
poly(propylenefumarate).
The monofunctional terminated unsaturated
polyester A block is reacted with the B block flexible
polymer to yield a block copolymer. If the flexible B
block is mono-terminated, an AB type block copolymer
will be formed. If the flexible polymer B block is a
diterminated functional polymer, an ABA type block
copolymer will be formed. However, if a difunctional
terminated polyester A block is utilized with a
difunctional terminated flexible B block, an ABA type
block copolymer is produced along with generally small
amounts of an A(BA) n type block copolymer where n is 2
to 5. Typically, such mixtures contain a majority
amount, that is at least 50 percent and often at least
70, 80, or even 90 percent by weight of the ABA block
copolymer.
When the flexible polymer B block is hydroxyl
terminated, desirably the unsaturated polyester A block
contains a monofunctional, or less desirably a difunc-
tional, terminal acid end group so that an ester reac-
tion occurs and an ester linkage is formed. Similarly,
if the flexible polymer B block contains a carboxyl
terminal group, the unsaturated polyester A block end
group is desirably a hydroxyl so that an ester linkage
can be formed. In either situation, a conventional
esterification reaction is carried out in a manner well
known to the art. The net result is the formation of an
AB or an ABA block polymer and possible small amounts of
A(BA) n block copolymer having an ester linkage between
the blocks.
If the flexible B block is amine terminated,
desirably the polyester A block has a monocarboxylic
acid functional end group. Such a reaction is carried
out in a conventional manner and results in an amide
linkage. Alternatively, if the polyester A block is
amine-terminated, a diisocyanate can be reacted with a
mono- or di- hydroxyl terminated B block, so that the
- 2 1 1 ~ 5 3 i
- 10 -
reaction product thereof with the amine-terminated A block
results in a urea linkage.
Regardless of the type of linkage formed between
the "A" block and the "B" block, the reaction conditions
for forming such linkages are well known to the art and to
the literature, and result in the formation of a novel
block copolymer. Such reactions including the conditions
thereof, etc., as well as the linkage reactions set forth
hereinbelow are more fully defined in Advanced Organic
Chemistry, Reactions, Mechanisms, and Structures, J.
March, 2nd Edition, McGraw Hill, New York, NY, 1977.
It is to be understood that the A and B type
blocks are typically preformed polymers which are reacted
together and that no in situ polymerization of the A block
or the B block occurs. In other words, the present
invention is generally free of in situ polymerization or
polymerization of one of the blocks on an existing block
when the molecular weight of the A block is from about 500
or 600 to about 5,000.
It is also within the scope of the present
invention to utilize a polyester A segment of very low
molecular weight, such as for example from about 100 to
about 500 or 600, wherein the ester segment or A block is
merely the in situ reaction of a single or a few
dicarboxylic anhydride and cyclic oxide molecules, such as
maleic anhydride and propylene oxide. Preferably, the
flexible B block is hydroxyl terminated. Such low
molecular weight polyester A blocks result in a block
copolymer having a high ratio or amount of the flexible
polymer A block.
To prepare such low molecular weight A segments
or blocks, it is advantageous to react the hydroxy
terminated flexible B segment directly with the cyclic
anhydride and propylene oxide. Suitable catalysts for the
reaction include the double metal cyanide complex
.
,~ ,
:.,
-- - 11- 2111~31
catalysts described above as well as the various titan-
ates and alkyl substituted tin compounds like dibutyltin
oxide. Preferred anhydrides for making such low molecu-
lar weight A segments have unsaturation such as maleic,
tetrahydrophthalic, itaconic, nadic, methyl nadic and
the like, although mixtures of unsaturated and saturated
cyclic anhydrides may also be used. Generally, any
cyclic oxide can be used with ethylene and propylene
oxides being preferred.
According to the preferred embodiment of the
present invention, the flexible polymer B block is
hydroxyl terminated and is reacted with a monohydroxyl
terminated unsaturated polyester A block through the
utilization of a polyisocyanate to yield a block copoly-
lS mer having a minimum molecular weight of 500 or 600.
That is, a polyisocyanate is reacted with the hydroxyl
end group of the flexible polymer B block thereby
leaving a free isocyanate group which is subsequently
reacted with the hydroxyl end group of the unsaturated
polyester A block. Examples of polyisocyanates which
can be utilized generally have the formula
R(NCO)n
where n is generally about 2 (i.e. a diisocyanate)
although it can be slightly higher or lower as when
mixtures are utilized. R is an aliphatic having from
about 2 to about 20 carbon atoms with from about 6 to
about 15 carbon atoms being preferred or an aromatic
including an alkyl substituted aromatic having from
about 6 to about 20 carbon atoms, with from about 6 to
about 15 carbon atoms being preferred, or combinations
thereof. Examples of suitable diisocyanates include
1,6-diisocyanato hexane, 2,2,4-and/or 2,4,4-trimethyl
hexamethylene diisocyanate, p-and m-tetramethyl xylene
diisocyanate, dicyclohexylmethane-4,4'-diisocyanate
(hydrogenated MDI), 4,4-methylene diphenyl isocyanate
(MDI), p- and m-phenylene diisocyanate, 2,4- and/or 2,6-
toluene diisocyanate (TDI), durene-1,4-diisocyanate,
- 12 - 211 15~ 1
isophorone diisocyanate, (IPDI) isopropylene-bis-(p-
phenyl isocyanate) and sulfone-bis-(p-phenyl
isocyanate). Also useful are diisocyanates prepared by
capping low molecular weight, that is less than 300,
diols, ester diols or diamines with diisocyanates, such
as the reaction products of one mole of 1,4-butanediol
or bis-(4-hydroxylbutyl)-succinate (molecular
weight=262) with two moles of hexamethylene diiso-
cyanate. TDI and IPDI are preferred for reasons set
forth herein below. The reaction between the diiso-
cyanate and the hydroxyl terminated flexible polymeric
B block is carried out in an inert atmosphere such as
nitrogen, at ambient temperatu-res and up to 30C,
desirably in the presence of urethane catalysts. Such
catalysts are known to the art as well as to the litera-
ture and generally include tin compounds such as various
stannous carboxylates, for example stannous acetate,
stannous octoate, stannous laurate, stannous oleate and
the like; or dialkyl tin salts of carboxylic acids such
as dibutyltin diacetate, dibutyltin dilaurate, dibutyl-
tin maleate, dibutyltin di-2-ethylhexoate, dilauryltin
diacetate, dioctyltin diacetate and the like. Similar-
ly, there can be used a trialkyltin hydroxide, dialkyl-
tin oxide or dialkyltin chloride. As an alternative or
in addition to the above tin compounds, various tertiary
amines can be used such as triethylamine, benzyldimeth-
ylamine, triethylenediamine and tetramethylbutanedi-
amine. The tin catalysts, when utilized, are generally
used in amounts of 0.5 parts or less, i.e., in the range
of about 0.01 to 0.5 parts, by weight per 100 parts of
prepolymer. The tertiary amine catalysts, when uti-
lized, can be used in amounts of 0.01 to about 5 parts
by weight per 100 parts of prepolymer.
It is an important aspect of the present
invention that the reaction of the diisocyanate with
mono- or di- hydroxyl terminated flexible polymer B
block occurs separately, that is, not in the presence
- 13 - 211i531
of, in the absence of, or free from the mono- or di- -
hydroxyl functional unsaturated polyester A block. This
ensures that a random copolymer containing block seg-
ments therein is not produced. Moreover, it is another
important aspect of the present invention to utilize
diisocyanate catalysts which have differential reaction
rates with regard to the two isocyanate end groups.
This is to ensure that only one of the groups reacts
with the hydroxyl terminated flexible B block and the
remaining unit generally remains unreacted until subse-
quent reaction of the monohydroxyl terminated polyester
A block. For this reason, TDI and IPDI are preferred.
The amount of the diisocyanate utilized is generally an
equivalent amount to the hydroxyl groups in the flexible
B block and thus is an equivalent ratio of from about
0.8 to about 1.2, and desirably from about 0.9 to about
1.1. Similarly, the amount of the polyester block A is
generally an equivalent amount to the urethane linkages
of the flexible B block, be it one linkage or two
linkages per B block.
The mono- or di- hydroxyl terminated unsatu-
rated polyester A block is then subsequently added to
the vessel or solution containing the urethane terminat-
ed flexible polymer B block and reacted therewith in a
conventional manner well known to the art and to the
literature. The result is a urethane linkage between
the polyester A block and the flexible polymer B block.
A distinct advantage of utilizing the urethane
reaction route is that a low temperature reaction can be
carried out which minimizes side reactions and that no
unreacted compounds remain which have to be removed from
the reaction product.
Another method of making a mixture of block
copolymers containing a large amount of AB block copoly-
mer is to react a diisocyanate-terminated flexible
polymer B block having two free NCO groups thereon with
an approximately equivalent amount of a low molecular
- 14 -
weight alcohol and then subsequently reacting the
product with an approximately e~uivalent amount of the
functional terminated unsaturated polyester A block.
The flexible polymer B block will contain a mixture of
alcohol terminated end groups, unreacted urethane end
groups, or both. The low molecular weight alcohol can
be methanol, ethanol, n-propanol, isopropanol, t-buta-
nol, and the like. In lieu of the low molecular weight
saturated alcohol, a functional compound containing an
ethylenically unsaturated polymerizable group can be
utilized, such as hydroxy-styrene, hydroxy-ethyl-acry-
late, methacrylate, or allyl alcohol.
Another preferred embodiment relates to the
preparation of the low molecular weight A blocks which
involves the reaction of hydroxyl terminated B blocks
with a cyclic unsaturated anhydride and an alkalene
oxide as noted above. Mixtures of saturated and unsatu-
rated anhydrides can also be used.
Another aspect of the present invention is
that the above-noted AB, or ABA, or A(BA)n block copoly-
mers can be cured. Curing can occur utilizing conven-
tional compounds such as ethylenically unsaturated
compounds, for example vinyl or allyl compounds, and
conventional free radical catalyst. Examples of
ethylenically unsaturated compounds include styrene, a
preferred compound, vinyl toluene, divinyl benzene,
diallyl phthalate, and the like; acrylic acid esters and
methacrylic acid esters wherein the ester portion is an
alkyl having from 1 to 10 carbon atoms such as
methylacrylate, ethylacrylate, n-butylacrylate, 2-ethyl-
hexylacrylate, methyl methacrylate, ethylene glycol
dimethacrylate, and the like. Other unsaturated mono-
mers include vinyl acetate, diallyl maleate, diallyl
fumarate, vinyl propionate, triallylcyanurate, and the
like, as well as mixtures thereof. The amount of such
compounds based upon 100 parts by weight of the block
copolymers can generally vary from about 1 to about 500
2 t ~ ~L ~ ~ 1
- 15 -
parts by weight, and desirably from about 1 to about 100
parts by weight. The free radical initiators can
include organic peroxides and hydroperoxides such as
benzoyl peroxide, dicumyl peroxide, cumene
hydroperoxide, paramenthane hydroperoxide, and the like,
used alone or with redox systems; diazo compounds such
as azobisisobutyronitrile, and the like; persulfate
salts such as sodium, potassium, and ammonium
persulfate, used alone or with redox systems; and the
use of ultraviolet light with photo-sensitive agents
such as benzophenone, triphenylphosphine, organic
diazos, and the like.
The invention will be understood by reference
to the following examples setting forth the preparation
of unsaturated polyester-blocked flexible polymer
composltlons.
Example 1
Poly(propylene fumarate)-b-poly(butadiene)-
b-~oly(propylene fumarate~ triblock
In a l-L resin kettle equipped with thermome-
ter, heating mantle and stirring were charged 203g (70
mmoles -OH) of BFG Hycar~ 2,000x169 (a dihydroxy-termi-
nated polybutadiene), 263g of styrene, 15.7g (141 mmoles
total -NCO) of isophorone diisocyanate, 2.3g of zinc
stearate, and 1.4g of DABCO~ T9 catalyst. The materials
were mixed thoroughly under nitrogen and warmed to 70C.
After two hours 80g (70 mmoles -OH) of a 80 percent
solids in styrene solution of a mono-hydroxy unsaturated
polyester (polypropylene fumarate, 850 MW) was added to
the reaction mixture, along with 2.5g of 10 percent
benzoquinone in diallyl phthalate, and 0.5g of DABCO~ T9
catalyst. The reaction mixture was cooled after three
hours to room temperature, and the solution poured into
a suitable container. The triblock had a flexible
polymer to unsaturated polyester weight ratio of 3.2 to
1.0, and contained 50 percent solids in styrene.
Example 2
21~1531
- 16 -
Poly(propYlene fumarate)-b-poly(butadiene-CO-
acrYlonitrile)-poly(propylene fumarate) triblock
The above triblock was prepared by charging a
2-L resin kettle as above with 600g (370 mmoles -OH) of
Hycar~ 1300x34 (a dihydroxy-terminated poly(butadiene-
CO-acrylonitrile, 26 percent AN content) and 480g of
styrene which was stirred overnight under nitrogen to
dissolve. To the stirred solution was then added 52g
(600 mmoles total -NCO) of toluene diisocyanate, and
2.0g DABCOæ T12 catalyst. The mixture was stirred for
one-half hour during which time the temperature rose to
37C, followed by the addition of 675g (350 mmoles -OH)
of an 80 percent solids in styrene solution of a mono-
hydroxy unsaturated polyester (polypropylene fumarate,
approx. 1600 MW). The mixture was kept at 37C with
stirring for six hours, and then poured into a contain-
er. The triblock had a flexible polymer to unsaturated
polyester weight ratio of 1.1 to 1.0, and contained 65
percent solids in styrene.
ExamPle 3
Poly(propylene fumarate)-b-poly(butadiene) block
copolymer
The above block copolymer was prepared by
charging 200g (70 mmoles -OH) of Hycar~ 2,000x169 to a
1-L resin kettle along with 234g of styrene, 12.5g (113
mmoles total -NCO) isophorone diisocyanate, 2.0g of zinc
stearate, and 2.0g DABCO~ T9 catalyst. The starting
materials were mixed thoroughly under nitrogen, and then
heated to 70C. After 90 minutes, 1.7g (28 mmoles -OH)
of n-propanol was added, and after 2.5 hours 36g (32
mmoles) of an 80 percent solids in styrene solution of
a monohydroxy unsaturated polyester (polypropylene fuma-
rate, approx. 1400 MW). The mixture was stirred for
another three hours, then cooled and transferred to a
suitable container. The block copolymer had a flexible
polymer to unsaturated polyester weight ratio of 7.0 to
1.0, and contained 53 percent solids in styrene. This
- 17 - 2~ 31
composition was a mixture containing large amounts of an
AB block copolymer.
Example 4
Poly(propylene fumarate)-b-~oly(butadiene-CO-
5acrylonitrile) block copolymer
The above block copolymer was prepared in a 1-
L resin kettle as above with a charge of 361g (225
mmoles -OH) Hycar~ 1300x34 and 175g (210 mmoles total -
OH) of 80 percent solids in styrene solution of di-
10hydroxy unsaturated polyester (polypropylene fumarate,
approximately 1400 MW), which were mixed thoroughly at
110C under vacuum for 90 minutes. The blend was cooled
to 80C under nitrogen, and 21.6g (250 mmoles total -
NCO) of TDI added followed by stirring for ten minutes.
15DABCO~ T-12 catalyst (0.8g) was added, causing an
immediate increase in viscosity. Stirring was continued
for one hour and the mixture cooled to 50C, followed by
the addition of 53lg of styrene. The solution was
transferred to a suitable container. The flexible
20polymer to unsaturated polyester weight ratio of this
additive was 2.6 to 1.0, and the solution contained 48
percent solids in styrene. This composition was a
mixture containing A(BA) n block copolymers.
ExamPle 5
25Poly(pro~ylene fumarate)-b-poly(butadiene-co-
acrylonitrile) block copolymer
The above block copolymer was prepared by
charging a 500-ml resin kettle with 189g of a solution
of Hycar~ 1300x31 (dicarboxy terminated polybutadiene-
30co-acrylonitrile, 10 percent AN content; 48.5 weight
percent, 91.5g, 51 mmoles carboxyl) and dihydroxy termi-
nated polypropylene fumarate (1300 MW; 51.5 percent,
97.5g, 150 mmoles -OH). The kettle was heated under
vacuum at 150 to 160C for two hours to remove water.
35The product was transferred to a suitable container.
The block copolymer had a flexible polymer to unsaturat-
ed polyester weight ratio of 0.9 to 1Ø This composi-
21~1531
- 18 -
tion contained ABA block copolymers.
Example 6
Poly(propylene fumarate)-b-~olY(butadiene-co-
acrylonitrile) block copolymer
The above block copolymer was prepared by
charging a 1.5-L resin kettle with 508g (726 mmoles -OH)
of unsaturated polyester (dihydroxy terminated poly-
propylene fumarate, approximately 1400 MW) 404g (234
mmoles carboxyl of Hycar0 1300x13 (dicarboxy terminated
polybutadiene-co-acrylonitrile, 26 percent AN content),
0.4g benzoquinone, and 0.4g of triphenylphosphonium
bromide. The mixture was stirred and heated to 150C
under vacuum for four hours. After cooling to room
temperature, 508g of styrene was added and mixed to
dissolve the polymer. The product was transferred to a
suitable container. The block copolymer had a flexible
polymer to unsaturated polyester ratio of 0.8 to 1.0,
and contained 57 percent solids in styrene. This
composition contained ABA block copolymers.
Example 7
Poly(Propylene fumarate)-b-Poly(tetrahydrofuran)-
b-poly(propylene fumarate) triblock
The above triblock was prepared by combining
400 grams of isocyanate-terminated poly(tetrahydrofuran
347 mmoles NCO), available from Air Products under the
trademark PET9OA, 312 grams of toluene, 3 grams of
DABCO0 T90 catalyst, available from Air Products and
Chemical Inc., and 224 grams of a solution of mono-
hydroxy-terminated poly(propylene fumarate) (80 percent
solids in styrene, 347 mmoles total -OH) in a one liter
resin kettle equipped with nitrogen purge, a heating
mantle, and a stirrer. The reagents were thoroughly
mixed at room temperature under nitrogen, after which
the contents were heated and maintained at 40C until
the reaction was complete. The progress of the reaction
was monitored using FTIR. Completion of the reaction
- was marked by the disappearance of the -NCO absorbance
~ 1 11531
-- 19 --
from the IR spectrum, at which time the product was
cooled to room temperature. This triblock copolymer had
a flexible polymer to unsaturated polyester ratio of
approximately 2 to 1.
5 Example 8
A poly(pro~ylene fumarate)-b-poly(butadiene)-
b-~oly(propylene fumarate) triblock
The above triblock was prepared by combining,
in a one liter resin kettle equipped with nitrogen
10purge, heating mantle, and stirrer, 500 grams of hy-
droxy-terminated polybutadiene (137 mmoles total OH),
available from the BFGoodrich Chemical Company under the
trademark HYCAR~ 2,000X169~, 310 grams of toluene, 31
grams of isophorone diisocyanate having 279 mmoles total
15-NCO, and 3 grams of DABCO~ T9~ catalyst. The contents
were thoroughly mixed under nitrogen, and then warmed to
60C for 2.5 hours. To the kettle were added 93 grams
of a solution of monohydroxy-terminated poly(propylene
fumarate) (80 percent solids in styrene, 144 mmoles
20total -OH), and 150 grams of toluene to reduce the
viscosity. The contents were reacted for about 3 hours
at 60C until the IR spectrum indicated complete con-
sumption of -NCO. The product was then cooled to room
temperature. This triblock copolymer had a flexible
25polymer to unsaturated polyester ratio of 6.2 to 1Ø
The above-identified diblock and triblock,
etc., polyester-flexible polymer copolymers can be
utilized as toughening agents in a variety of plastics
such as unsaturated polyesters or vinyl ester resins.
30Moreover, they can be directly applied to a fiber
structure and cured to coat the same and alleviate
stress cracking on the surface of the fibers. Subse-
quently, the fiber structure coated with the cured
polyester-flexible polymer block copolymers of the
35present invention can be utilized in various matrix
formations such as in sheet molding coatings, in the
preparation of sheet resins containing fiber reinforce-
- 20 - 21 1 1531
ment therein, in the preparation of fiber structures
utilized in mats, nonwovens, wovens, and the like, in wet
lay-up sheets, in resins utilized in injection molding,
bulk molding, and the like.
DETAILED DESCRIPTION OF IN-MOLD COATING COMPOSITIONS
An in-mold coating for molded thermoset plastic
parts using the AB, ABA, or A(BA)n block copolymers of the
Detailed Description of the Block Copolymers has greater
elongation and flexural strain to failure than previous
in-mold coatings while maintaining good surface quality
and paintability. The in-mold coating can alternatively
use certain telechelic flexible polymers in lieu of the
AB, ABA, or A(BA) n block copolymers or in combination with
them.
An in-mold coating needs to have low viscosity
so that it can flow out in an even layer over large
compression molded parts in relatively short periods of
time. It is also desirable that the coating have storage
stability such that it does not prematurely cure nor phase
separate during storage or equipment shutdowns. An in-
mold coating needs resistance to abrasion, solvents, and
external deformations while retaining good adhesion to the
substrate and sufficient flexibility to prevent cracking
on flexural strains. In-mold coating components are well
known to the art and described in patents such as U.S.
Patent No. 4,515,710. The components and processing of
that patent can be included in the present composition.
In that the coating is chemically crosslinked by heating,
it is generally known as a thermoset.
The components of this in-mold coating include
a) polymerizable vinyl ester resin, b) ethylenically
unsaturated monomers, c) low profile additive and/or
adhesion promoter, d) mold release agents, e) a telechelic
flexible polymer or an AB, ABA, or A(BA)n block copolymers
-
- 21 - 2111531
where the B block is a flexible polymer and the A block is
an unsaturated polyester and n is from 1 to 5, f) free
radical source, and optionally, carbon black or conductive
filler, and/or nonconductive fillers. The parts by weight
recited are based on each component before diluting or
dissolving them in other components.
a. The polymerizable vinyl ester resin is well
known to the art, is commercially available, and is the
reaction product of a poly epoxide and an unsaturated
monocarboxylic acid, having at least two acrylate (or
methylacrylate or ethacrylate) groups. Said
monocarboxylic acid preferably has 3 to 10 carbon atoms.
It can be prepared from reacting acrylic methacrylic, or
ethacrylic acid and so forth with an epoxy, tetrabromo
Bisphenol A epoxy, phenolic novolac epoxy, tetraphenylol-
ethane epoxy, dicycloaliphatic epoxy, and so forth.
Mixtures of these epoxy based vinyl ester oligomers may be
used. Of these materials, it is preferred to use a
diacrylate terminated Bisphenol A epoxy oligomer. They
have weight average molecular weights from about 500 to
1500 and desirable from about 500 to about 1000. Further
examples of vinyl ester resins re given in Developments in
Reinforced Plastics-1, Resin Matrix Aspects, edited by G.
Pritchard, Applied Science Publishers Ltd: London 1980,
Chapter 2, pages 29-58. The vinyl ester resin is used in
the amount of 100 parts by weight.
b. One or more ethylenically unsaturated
monomers are used to copolymerize with and to crosslink
the copolymerizable oligomers. They include styrene
(preferred), alpha methyl styrene, vinyl toluene,
t-butyl styrene, chlorostyrene, methylmethacrylate,
diallyl phthalate (with styrene or methyl methacrylate
and the like), triallyl cyanurate, triallyl iso-
cyanurate, divinyl benzene, methyl acrylate and so
~j ,
2111531
- 22 -
forth, and mixtures thereof. The unsaturated
ethylenically unsaturated monomers are used from about
80 to about 200 parts and desirably from about 100 to
about 160 parts by weight per 100 parts by weight of
polymerizable epoxy based oligomer, that is the vinyl
ester resin.
For further copolymerization and crosslinking
and to improve hardness of the resulting coating, the
ethylenically unsaturated monomers used in the in-mold
coating composition can be partially replaced with a
monoethylenically unsaturated compound having a
-C=O group and having a - NH2, -NH- and/or -OH group.
Examples of such monomeric compounds are hydroxyl propyl
methacrylate (preferred), hydroxyethyl methacrylate,
hydroxy ethyl acrylate, hydroxy ethyl crotonate,
hydroxypropyl acrylate, hydroxy polypropylene
methacrylate, hydroxy polyoxyethylene methacrylate,
acrylamide, methacrylamide, N-hydroxymethyl acrylamide,
N-hydroxymethyl methacrylamide and so forth, and
mixtures of the same. These ethylenically unsaturated
monomers having polar groups can be used in an amount of
from about 10 to about 120 parts by weight per 100 parts
by weight of the vinyl ester resin.
c. Low profile additives are included to
minimize shrinkage on curing. Typical low profile
additives are well known to the art and include
poly(vinyl acetate), saturated polyesters, polyacrylates
or polymethacrylates, saturated polyester urethanes, and
the like. A preferred low profile additive is
carboxylated poly(vinyl acetate) which tends to improve
paint adhesion to the coating and the hardness of the
coating. The acid number of the carboxylated poly(vinyl
acetate) can range from 0 to 4. These can be used from
about 5 to about 90 parts, preferably 10 to 60 parts by
weight per 100 parts by weight of vinyl ester resin.
d. Mold release agents include zinc salts of
_ - 23 - ~ 53 1
fatty acids having at least 10 carbon atoms or mixtures
thereof. The fatty acid salts of zinc appear to
function as a mold release agent and as secondary
accelerator for cure. Fatty acids are well known. See
"organic Chemistry" Fieser and Fieser, D.C. Health and
Company, Boston 1944 pages 88, 381-390, 398 and 401, and
"Hackh's Chemical Dictionary," Grant, McGraw Hill Book
Company, New York, 1969, P. 261. Examples of zinc salts
are zinc palmitate, zinc stearate, zinc ricinoleate and
the like. Zinc salts of saturated fatty acids such as
zinc stearate are preferred. The zinc salt is used in
an amount of from about 0.2 to about 5 parts by weight
per 100 parts by weight of the vinyl ester resin.
A calcium salt of a fatty acid having at least
10 carbon atoms in an amount of from about 0.2 to 5
parts by weight of calcium salt per 100 parts by weight
of the polymerizable epoxy based oligomer can be used in
the in-mold coating composition as a mold release agent
and to control the rate of the cure. These fatty acids
are well known, as seen above for zinc. Mixtures of
calcium salts of the fatty acids can be used. Examples
of some calcium salts are calcium stearate, calcium
palmitate, calcium oleate and the like. It is preferred
to use the calcium salt of a saturated fatty acid like
calcium stearate.
- e. The telechelic flexible polymers can have
hydroxyl functional end groups. They can desirably have
average functionalities per polymer of from about 1.5 to
about 3.0, and preferably from about 1.7 to about 2.5.
These polymers can have more than two terminal ends
because of potential grafting reactions with diene
polymerizations. The flexible polymers have a Tg of
about 0 or less, desirably below -20C, often are
liquid, and are readily known in the art and to the
literature. These are the same flexible polymers B used
in the AB or ABA block copolymers. Their molecular
weight is from about 500 to about 20,000, and desirably
2 1 1 1 53 1
- 24 -
from about 500 to about 5,000. They can be made from any
polymerization method including free radical and anionic
methods. Polymers from diene monomers (especially
conjugated dienes) are preferred along with copolymers of
dienes and vinylic monomers. Vinylic monomers useful in
this application include styrene; substituted styrenes
such as alpha methyl styrene or ortho, meta, para alkyl
substituted styrenes, and acrylonitrile. The preferred
polymers are poly(butadiene) and poly(butadiene-co-
acrylonitrile).
The AB or ABA block copolymers can be any of the
AB, ABA, or A(BA) n block copolymers described in the
Detailed Description. The preferred B blocks are those
from conjugated dienes such as butadiene or copolymers
from conjugate dienes such as butadiene-styrene or
butadiene acrylonitrile copolymers. The B blocks can be
made by any polymerization method including free radical
or anionic methods. The B blocks for this application
desirably have molecular weights from about 500 to about
20,000, and preferably from about 500 to about 5,000.
Preferably the A blocks are monofunctional. Methods to
prepare monofunctional polyesters are disclosed in U.S.
Patent 3,538,043 to R. J. Herold.
The telechelic flexible polymers or the AB, ABA,
or A(BA) n block copolymers can be used singly or in
combination to result in from about 1 to about 35,
desirably from about 2 to about 30, and preferably from
about 4 to about 20 parts by weight flexible polymer B
based upon 100 parts by wéight of the vinyl ester resin.
For the purposes of this application, the A block of said
block copolymers will not be counted in the parts by
weight of flexible polymer.
f. An organic free-radical source or free
radical generating initiator (catalyst) such as a peroxide
is used to catalyze the polymerization, copolymerization
and/or crosslinking of the . . . . . . . . . . . . . . .
... . ..
~,,
- 25 - 2111531
ethylenically unsaturated oligomers and the other
ethylenically unsaturated materials. Examples of free-
radical initiators include tertiary butyl perbenzoate,
tertiary butyl peroctoate in diallyl phthalate, diacetyl
peroxide in dimethyl phthalate, dibenzoyl peroxide,
di(p-chlorobenzoyl) peroxide in dibutyl phthalate,
di(2,4-dichlorobenzoyl) peroxide with dibutyl phthalate,
dilauroyl peroxide, methyl ethyl ketone peroxide,
cyclohexanone peroxide in dibutyl phthalate, 3,5-
dihydroxy-3,4-dimethyl-1,2-dioxacyclopentane, t-
butylperoxy(2-ethyl hexanoate), caprylyl peroxide, 2,5-
dimethyl-2,5-di(benzoyl peroxy) hexane, 1-
hydroxycyclohexyl hydroperoxide-1, t-butyl peroxy (2-
ethylbutyrate), 2,5-dimethyl-2,5-bis(t-butyl peroxy)
hexane, cumyl hydroperoxide, diacetyl peroxide, t-butyl
hydroperoxide, ditertiary butyl peroxide, 3,5-dihydroxy-
3,5-dimethyl-1,2-oxacyclopentane, and 1,1-bis(t-
butylperoxy)-3,3,5-trimethyl cyclohexane and the like
and mixtures thereof. It is desirably sometimes to use
mixtures of initiators to take advantage of their
different decomposition rates and times at different
temperatures and so forth. A preferred initiator to use
is tertiary butyl perbenzoate. The peroxide initiator
should be used in an amount sufficient to overcome the
effect of the inhibitor and to cause crosslinking or
curing of the ethylenically unsaturated materials. In
general, the peroxide initiator is used in an amount of
up to about 5 percent, preferably up to about 2 percent,
by weight based on the weight of the ethylenically
unsaturated materials employed in the in-mold coating
composition.
To prevent premature gelation of the
ethylenically unsaturated materials and to provide for
improved shelf-life or storageability, inhibitors are
added in the desired amount to the composition or are
provided in the raw materials before use. Examples of
inhibitors are hydroquinone, benzoquinone, p-t-butyl
` - 26 - ~IL1531
catechol and the like and mixtures thereof.
An accelerator can be used for the peroxide
initiator and is a material such as a drier, e.g.,
cobalt octoate (preferred). Other materials which may
be used are zinc naphthenate, lead naphthenate, cobalt
naphthenate and manganese naphthenate. Soluble Co, Mn,
and Pb salts of linoleic acid, also, may be used.
Mixtures of accelerators may be used. The accelerator
is used in an amount of from about 0.01 to 1 part by
weight per 100 parts by weight of the polymerizable
epoxy based oligomer.
Conductive carbon black can be used in the in-
mold coating composition in an amount of from about 5 to
about 40 parts and desirably from about 10 to about 30
parts by weight per 100 parts by weight of the
polymerizable epoxy based oligomer. These are high
structure carbon blacks such as Vulcan~ XC-72R from
Cabot Corporation. They achieve conductivity by
achieving a critical concentration in the coating such
that a continuous carbon network is created that
conducts electricity. Other conductive fillers could
also be used.
A filler can be used in the in-mold coating
composition in an amount of from about 50 to 155 parts
by weight per 100 parts by weight of the polymerizable
epoxy based oligomer. Examples of fillers include clay,
MgO, Mg(OH)2, CaC03, silica, calcium silicate, mica,
aluminum hydroxide, barium sulfate, talc, hydrated
silica, magnesium carbonate and mixtures of the same.
The fillers should be finely divided. Of these fillers,
it is preferred to use talc. Fillers can afford the
desired viscosity and flow to the in-mold composition
for molding and contribute to the desired physical
properties in the resulting thermoset in-mold coating.
Fillers, also, may improve adhesion. However, care
should be exercised in the use of high filler contents
as this may give high viscosities and result in flow and
- 27 - ~1~15~1
handling difficulties.
The in-mold coating composition additionally
optionally may be compounded with other ingredients such
as mold release agents, antidegradants, W absorbers,
paraffin wax, solid glass or resin micro-spheres,
thickening agents, low shrink additives and the like.
These compounding ingredients should be used in amounts
sufficient to provide satisfactory results.
For ease in handling, materials like
carboxylated polyvinylacetate may be dissolved in a
reactive monomer like styrene. The viscosity of the
oligomers may be reduced by dilution with styrene and
the like. The ingredients of the in-mold composition
should be readily mixed by stirring together the
monomers and polymers. Subsequently, the other
ingredients and the fillers can be added. The viscosity
will increase when the filler is added. They can be
handled at ambient or room temperature or temperatures
below the polymerization temperature so that they may be
readily pumped to the mold and injected into the same.
The ingredients may be warmed or heated before or during
mixing and mixed in steps to facilitate thorough mixing,
dispersion and solution of the same. Also, the bulk of
the ingredients can be thoroughly mixed and the
remainder, including the catalyst, separately mixed and
then both can be pumped to a mixing head to be mixed
together and then injected into the mold.
With the peroxide initiator or catalyst, the
in-mold composition exhibits a shelf-life at room
temperature (about 25C) of about a week, and without
the initiator it exhibits a shelf life of several months
at room temperature . The initiator is preferably added
to the composition and thoroughly mixed therewith just
before molding.
All of the ingredients of the in-mold coating
composition should be kept dry or have a minimal amount
of moisture or the water content should be controlled to
21~15~ 1
- 28 -
obtain reproducible results and to prevent pore
formation.
Mixing of the ingredients of the in-mold
composition should be thorough. Injection molding,
compression molding, transfer molding, or other molding
apparatus or machines can be used for the in-mold
coating. Molding apparatus and methods may be found in
U.S. Patent Nos. 4,076,780; 4,076,788; 4,081,578;
4,082,486; 4,189,517; 4,222,929; 4,245,006; 4,239,796;
4,239,808 and 4,331,735. Please see also, "Proceedings
of the Thirty-Second Annual Conference Reinforced
Plastics/Composites Institute," SPI, Washington,
February, 1977, Griffith et al., Section 2-C, pages 1-3
and "33rd Annual Technical Conference, 1978, Reinforced
Plastics/Composites Institute, The Society of the
Plastics Industry, Inc.," SPI, Ongena, Section 14-B,
pages 1-7. The in-mold coating composition can be
applied to the substrate and cured at a temperature of
from about 290 to 310 F and at a pressure of about 1000
psi for from about 0.5 to 3 minutes. This creates a
laminate with a fiber reinforced plastic being the
substrate.
The processes and products of the present
invention can be used in the manufacture of automobile
parts such as grille and headlamp assemblies, deck
hoods, fenders, door panels and roofs, as well as in the
manufacture of food trays, appliance and electrical
components, furniture, machine covers, and guards,
bathroom components, structural panels and so forth.
The glass fiber reinforced thermoset plastic (FRP) such
as the polyester resin or vinyl ester resin and glass
fiber composition substrate to which the in-mold
composition is applied can be a sheet molding compound
(SMC) or a bulk molding compound (BMC), or other
thermosetting FRP material as well as a high strength
molding compound (HMC) or a thick molding compound. The
FRP substrate can have from about 10 to 75 percent by
- 29 - 2111531
weight of glass fibers. The SMC compound usually
contains from about 25 to 30 percent by weight of glass
fibers while the HMC compound may contain from about 55
to 60 percent by weight of glass fibers. The glass
fiber reinforced thermoset plastic (FRP) substrate can
be rigid or semirigid (may contain a flexibilizing
moiety such as an adipate group in the polyester). The
substrate, also, may contain other flexibilizing
polymers, the elastomers and plastomers such as the
styrene-butadiene block copolymers. Unsaturated
polyester glass fiber thermosets are known as shown by
"Modern Plastics Encyclopedia," 1975-1976, October,
1975, Vol. 52, No. 10A, McGraw-Hill, Inc., New York,
pages 61, 62 and 105 to 107; "Modern Plastics
Encyclopedia," 1979-1980, October, 1979, Volume 56,
Number 10A, pages 55, 56, 58, 147 and 148 and "Modern
Plastics Encyclopedia," 1980-81, October, 1980, Volume
57, Number 10A, pages 59, 60, and 151 to 153, McGraw-
Hill, Inc., New York, N.Y.
The compositions of the present invention can
exhibit good pumpability and flow in the mold. They can
give rapid cures in time periods as low as 50 to 90
seconds at 300F. They also show good adhesion to
paints and can be used not only as an in-mold coating to
cover blemishes but as a good conductive coating for
electrostatic painting and as a primer for most paint
finish systems such as soluble acrylic lacquers, acrylic
dispersion lacquers, water borne acrylic enamels, high
solids solution acrylic enamels, acrylic non-aqueous
dispersions and urethanes.
The following example will serve to illustrate
the present invention with more particularity to those
skilled in the art. The flexural properties were
evaluated using ASTM D790 while the tensile properties
were evaluated using ASTM D638-89. In the example, the
parts are parts by weight unless otherwise indicated.
~ 30 ~ 2 111 S~ 1
Example 11 Modifier A
This material was prepared in a one-liter,
three-neck resin kettle equipped with an air stirrer and
addition funnel. The system as swept with a flow of
nitrogen gas. Into the addition funnel was placed a
solution of 125 g (198.75 mmoles -OH) of hydroxy-
terminated polybutadiene, HTB (R20LM, Atochem~, approx.
1500 MW) in 246.5 g styrene. In the resin kettle was
added 44.2 g (397.7 mmoles -NCO) of IPDI (isophorone
diisocyanate aka [5-isocyanto-1-(isocyantomethyl)-
1,3,3-trimethylcyclohexane] and 1.7 g of DABCO~ T12
(dibutyltin dilaurate, Air Products). The solution of
HTB in styrene was added dropwise from the addition
funnel to the rapidly stirred IPDI. Heat was applied to
raise the temperature to 75C. The contents were
reacted for 1.5 hours.
The addition funnel was charged with a
solution of 105 g (209 mmoles -OH) of mono-hydroxy-
terminated poly(propylene fumarate), PPF, having a
nominal molecular weight of 700, and 0.7 g DABCO~ T12,
dissolved in 26.3 g of styrene. The solution of PPF in
styrene was added slowly to the above prepolymer
solution contained in the resin kettle. The reaction
mixture was maintained at a temperature of 65C for 4
hours and then allowed to cool to room temperature. The
weight ratio of flexible polymer to PPF was 1.2:1.
The procedure used to prepare the block
copolymer of this invention is considered to result in
ABA-type block copolymer, as well as products from chain
extension of hydroxy-terminated polybutadiene. This is
evident by the multimodal shape of the molecular weight
distributions.
Example 12 Modifier B
Modifier B was prepared according to Example
11 with hydroxy-terminated PPF having a nominal
molecular weight of 1400 substituted for the
corresponding PPF of 700 molecular weight. The weight
- 211~31
- 31 -
ratio of HTB to PPF was 0.45:1.
Example 13 Modifier C
This material was prepared according to
Example 11 by combining 122.47 g of hydroxy-terminated
polybutadiene (42.9 moles -OH), available as Hycar~ HTB
2000 x 169 having approximately 5000 MW from the B. F.
Goodrich Chemical Company; 473 g styrene; 9.53 g IPDI
(85.74 mmoles -NCO); and 0.3 g DABCO~ T9 (stannous
octoate) catalyst. To the prepolymer of IPDI and HTB
were added 71.25 g of a solution of 57 g mono-hydroxy-
terminated PPF (42.6 mmoles -OH), nominal number average
molecular weight of 1400, in 14.25 g styrene. The
contents were reacted for 2 hours at 60C at which point
the IR spectrum indicated complete consumption of -NCO.
The material had a flexible polymer to PPF ratio of
2.1:1.
Example 14 Modifier D
Modifier D was prepared according to Example
11 by combining, in a one-liter resin kettle, 391 g of
hydroxy-terminated polybutadiene (137 mmoles -OH, Hycar~
2000 x 169 having approximately 5000 MW), 310 g of
toluene, 31 g IPDI (279 mmoles under nitrogen), and then
warmed to 60C for 2.5 hours. To the kettle were added
74 g of a solution of mono-hydroxy-terminated PPF (144
mmoles -OH), nominal number average molecular weight of
700, and 150 g of toluene. The contents were reacted
for about 3 hours at 60C until the IR spectrum
indicated complete consumption of -NCO. The weight
ratio of flexible polymer to PPF was 6.8:1.
Example 15 Modifier E
This material was prepared according to
Example 14 with hydroxy-terminated polybutadiene (R45HT
supplied by Atochem~ approximately 3000 MW) substituted
for Hycar~ 2000 x 169 or an equivalent mole basis of OH
groups. The weight ratio of flexible polymer to PPF was
2.3:1.
Example 16 Modifier F
- 2111531
- 32 -
Modifier F was prepared by charging an
addition funnel attached to a one-liter resin kettle
with 94.0 g (42.4 mmoles -OH) of hydroxy-terminated
poly(butadiene-co-acrylonitrile) (available as HTBN
Hycar~ 1300 x 34, having approximately 4,000 MW, from
B.F. Goodrich, containing 26 percent acrylonitrile) and
141 g styrene which was stirred under nitrogen. In the
resin kettle was placed 9.41 g IPDI (84.67 mmoles -NCO)
and 0.5 g DABCO~ T12 catalyst. The solution of HTBN in
styrene was added dropwise to the rapidly stirred IPDI
liquid. After the initial exotherm, the reaction
mixture was heated to 50C for 2 hours followed by the
addition of a solution of 26.24 g (42.28 mmoles -OH) of
mono-hydroxy-terminated PPF, having a nominal number
average molecular weight of 700, in 6.6 g styrene. The
contents were reacted for 2 days at 55C. The weight
ratio of flexible polymer to PPF was 3.6:1.
Example 17 Modifier G
This material was prepared according to
Example 16 using a mono-hydroxy-terminated PPF having a
higher nominal number average molecular weight of 1400,
substituted for the PPF used in Example 16 on an
equivalent mole basis of OH. The weight ratio of
flexible polymer to PPF was 1.6:1.
The data in Tables II and III summarize four
telechelic hydroxy-terminated flexible polymers and
seven polyester-flexible block copolymers, evaluated a
toughness modifiers for IMC.
Tables I, II, and III summarize the above data
in table form giving the ratios of the components and
functionality in more detail. Table IV gives a typical
in-mold coating (IMC) formulation used to generate the
physical properties data.
21 1 1 ~3 1
-- 33 --
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~D
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- o o o o o o o
o o o o o o o
r ~ ~ r ~ d~
c)
~ ~` I` d1
li3 --I ~_ ~ rl
m ~
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,~
O V
O ~` t` ~ ~` ~ ~ O
O I ~ ~ V
CD 0 N H N t~ ~ ~
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a a a a ~ a ~ ~
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.
2111~31
- 34 -
TABLE II
Hydroxy-Terminated Polymers Evaluated as
Toughness Modifiers For In-Mold Coating
Description Hydroxyl
Modifier (Supplier) Functionality
(approximate)
HTB Hydroxy-terminated 2.3
R20LM PolyBd (Atochem)~ (1500
MW)
HTB Hydroxy-terminated PolyBd 2.3
R45HT (Atochem)~ (3000 MW)
HTB Hydroxy-terminated PolyBd 1.8
2000X169 (B. F. Goodrich) (5000 MW)
HTBN Hydroxy-terminated Poly 1.8
1300X34 (Bd-co-AN), 26% AN
(B. F. Goodrich) (4000 MW)
TABLE III
Block Copolymers of Poly~propylene fumarate) End
Block and Poly(butadiene) or Poly(butadiene-co-
acrylonitrile) Center Block~
Modifier Center Block End Block
(Nominal MW)
A HTB (R20LM) PPF (700 MW)
(1500 MW)
B HTB (R20LM) PPF (1400 MW)
(1500 MW)
C HTB (2000X169) PPF (1400 MW)
(5000 MW)
D HTB (2000X169) PPF (700 MW)
(5000 MW)
E HTB (R45HT) PPF (700 MW)
(3000 MW)
F HTBN (1300X34) PPF (700 MW)
(4000 MW)
G HTBN (1300X34) PPF (1400 MW)
(4000 MW)
2111531
- 35 -
TABLE IV
IMC FORMULATION
Weight
In Parts
Modifiers of this Disclosure Variable
Vinyl Ester Resin* 100.00
Styrene (monomer) 85.00
Low Profile Additive 10.00
(poly(vinyl acetate))
Hydroxypropyl Methacrylate 30.00
2% Benzoquinone in Styrene 0.14
Zinc Stearate 1.85
Calcium Stearate 0.45
Cobalt Accelerator (12%) 0.15
in Mineral Oil
Carbon Black 8.50
Talc 80.00
t-Butyl Peroxybenzoate 1.60
* The molecular weight of the vinyl ester resin is
nominally 800-1000.
Formulation and Curing of IMC Containing Additives
The materials described in Examples 11-17 were
added to the IMC formulation shown in Table IV. The
additives were evaluated at concentrations of 2.5 and
5.0 weight percent (calculated as the polybutadiene or
poly(butadiene-co-acrylonitrile) content divided by the
weight of the IMC composition. After the appropriate
incorporation of the additives in the IMC formulation,
the modified IMC's were cured into slabs, having
dimensions of 15.24 x 5.08 x 0.25 cm and 5.08 x 5.08 x
0.25 cm, by compression molding.
Property Measurements
Flexural properties (ASTM D790) and tensile
properties (ASTM 638-89) were measured at room
temperature. The Mandrel Bending Test consisted of a
series of slots of decreasing radius. The test is run
2111~l
- 36 -
by fitting the sample (2.54 cm x 7.62 cm) into slot No.
1 (highest radius of curvature~. If no failure occurs
(i.e., the strip does not break), the test is repeated
progressively with slots No. 2, 3, 4, etc., until
failure occurs. The elongation is calculated using the
following equation:
% ELONGATION = T/2Rf,
where T is the thickness of the sample in inches and Rf
is the radius of curvature for the next higher radius at
which failure did not occur.
Mechanical ProPerties of Modified IMC's
The effect of hydroxy-terminated
polybutadienes, poly(butadiene-co-acrylonitrile) or
unsaturated polyester flexible block copolymers on
flexural and stress-strain properties are shown in
Tables V, VI, and VII. Table V gives the properties
using the commercial flexible materials used as received
as additives. Table VI shows the properties of these
flexible materials made into ABA block copolymers, as in
Table I, used as additives on an equivalent rubber
basis. Relative to unmodified IMC, flexible polymers of
HTB and HTBN and their corresponding copolymers with PPF
gave increased flexural moduli, flexural strength,
tensile strength and elongation at break. This was
obtained with no sacrifice in mold coverage and coating
performance. Compared to an IMC control, the modified
in-mold coated SMC's were equivalent in cross-hatch
adhesion (Ford BI6-1), degree of cure, pencil hardness,
pipe scratch resistance and chip resistance
(Gravelometer test, GM 9508P and GM 9071P). '
In general, flexural properties were enhanced
at additive levels of 2.5 weight percent and then, for
higher additive concentration (5.0 weight percent),
flexural properties decreased. Notwithstanding the
frequent breakage of samples at the jaw clamps of the
Instron Tester, tensile strength and elongation at break
are higher for the modified IMC samples.
2111~31
- 37 -
The elongation, as measured by the Mandrel
Bending Test, of three modified IMC's are compared with
the IMC control in Table VIII. The higher elongation
values of the IMC's containing hydroxy-terminated
polybutadienes and an unsaturated polyester flexible
block copolymer (Modifier A) indicate that the IMC
compositions of this disclosure have higher resistance
to crack-initiation than unmodified IMC.
TABLE V
Flexural Data at Room Temperature
of IMC containing Telechelic Modifiers
Modifier Wt% Modulus (GPa) Strength (MPa)
Rubber Low High Low High
IMC (Control) - 3.4 4.2 30.8 47.7
HTB R45HT 2.5 4.4 4.5 69.0 69.5
HTB R45HT 5.0 3.5 3.9 61.4 64.3
HTB 2000X169 2.5 3.9 4.2 62.3 65.8
HTB R20LM 2.5 4.2 4.3 41.3 60.4
HTB R20LM 5.0 3.7 3.8 58.1 61.0
HTBN 1300X34 2.5 4.4 4.6 58.8 60.4
HTBN 1300X34 5.0 3.5 4.0 58.0 58.4
2111531
- 38 -
TABLE VI
Flexural Data at Room Temperature
of IMC Containing Bloc~ Copolymer Modifiers
Modifiers Modulus (GPa) Strength (MPa)
of this Wt%
Disclosure Rubber Low High Low High
10 IMC (Control) - 3.4 4.2 30.8 47.7
A 2.5 3.8 4.6 70.7 78.0
5.0 3.3 3.5 38.0 68.0
B 2.5 4.0 4.4 65.7 73.8
5.0 3.5 4.2 45.7 69.4
C 2.5 3.8 4.4 50.0 74.1
5.0 3.6 3.8 49.2 57.0
D 2.5 3.6 4.0 52.7 67.0
5.0 3.2 3.5 56.2 73.6
E 2.5 3.6 3.6 48.4 70.0
5.0 3.8 4.3 66.7 66.7
F 2.5 4.0 4.7 62.6 65.8
5.0 4.1 4.3 65.9 67.0
G 2.5 3.8 4.4 61.0 65.1
5.0 3.8 3.8 57.4 72.2
~ _ 39 _ 2!1153~
TABLE VII
Tensile Strength and Elongation of
IMC Cont~; n; n~ Modifiers
Modifier Wt~Tensile ~ Elongation
RubberStrength at Break at RT
(MPa) at RT
Max Min Max Min
IMC - 30.1* 17.7* 0.6* 0.4*
(Control)
HTB R45HT 2.5 36.2 19.5* 1.3 0.4*
HTB 2.5 37.6 18.6* 1.5 0.6*
2000X169
HTB R20LM 2.5 36.1 23.6* 1.3 0.6*
HTBN 2.5 31.9* 22.3* 1.0*
1300X34
A 2.5 42.1 40.4 1.3 1.2
B 2.5 41.5 20.3* 1.4 0.3*
C 5.0 32.5 27.8 2.0 1.1
D 2.5 31.1* 23.6* 0.7* 0.5*
E 2.5 44.1 17.0* 1.7 0.4
F 2.5 29.6 27.7 1.4 1.3
G 2.5 39.6 38.4 1.6 1.5
Sample broke at the jaw clamps of the Instron Tester.
TABLE VIII
Elongation of IMC Cont~ining Modifiers
from Mandrel B~n~in~ Test
Sample* Average ~
Elongation
IMC (Control) 1.41
IMC + HTB R45HT 2.07
IMC + HTB 2000X169 2.07
IMC + B522-24 (Modifier A) 1.79
~at 2.5 wt~ rubber additive
The telechelic rubber polymers shown in Table
V increased both the room temperature flexural modulus
and room temperature flexural strength. These hydroxy
, .~ terminated polymers have molecular weights from about
., ~
~ 21il~31
-
- 40 -
1500 to about 5000. In this in-mold coating recipe, the
presence of these telechelic polymers does not cause
detrimental effects on smoothness or coating
performance.
The block copolymers of Table VI also show
increased flexural modulus and strength at room
temperature. Modifier A of this disclosure shows the
most dramatic improvement in properties. The benefit of
the poly(propylene fumarate) blocks can be seen from a
comparison of Modifier A in Table VI with HTB R2OLM in
Table V. The effect of molecular weight of the
poly(propylene fumarate) can be seen by comparing
Modifier A and B in Table VI. The effect of changing
the molecular weight of the poly(propylene fumarate) can
also be seen by comparing Modifiers C and D or Modifiers
F and G. The differences seem to be within experimental
error.
Table VII shows the tensile and elongation are
increased for in-mold coating compositions using the
hydroxyl terminated telechelic polymers or the block
copolymers of AB, ABA, or A(BA) n structure. Table VIII
shows the Mandrel Bending Test gives improved percent
elongation as would be predicted based on the tensile
and flexural tests.
While in accordance with the Patent Statutes,
the best mode and preferred embodiment has been set
forth, the scope of the invention is not limited
thereto, but rather by the scope of the attached claims.
