Note: Descriptions are shown in the official language in which they were submitted.
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PULTRUSION SYSTEMS AND PROCESS
Cross Reference to Related Applications
This application claims priority to U.S. Provisional Application, serial no.
60/520,765, which was filed on November 17, 2003, and U.S. Provisional
Application,
serial no. 60/560,295, which was filed on April 7, 2004.
Field of the Invention
The invention relates to polyisocyanate-based reaction systems, pultrusion of
1o those systems to produce reinforced matrix composites, and to composites
produced
thereby.
Background of the Invention
Pultrusion is a highly cost effective method for malting fiber reinforced
resin
matrix composites. The primary raw materials used in pultrusion are resin and
reinforcement. Fillers and additives, such as, but not limited to, calcium
carbonate, clay,
mica, pigments, and UV stabilizers, may be added to the resin to enhance the
physical,
chemical, and mechanical properties of the pultruded product.
Pultrusion is typically done by the injection die or open bath process. The
open
bath process is the most common. The injection die process, however, is
gaining ,
importance due to environmental concerns about the large amounts of volatile
contaminants released in the open bath process. In a typical open bath
process,
reinforcement material in the form of fibers, mat or roving is pulled
continuously through
an open bath of resin to produce an impregnated reinforcement. The impregnated
reinforcement is pulled through form plates to remove excess resin, and then
through a
curing die to cure the resin and yield a finished product. In the injection
die pultrusion
process, reinforcement material is passed through a closed injection die that
has resin
injection ports. The resin is injected under pressure through the ports to
impregnate the
reinforcement material. The impregnated reinforcement is pulled through the
injection die
3o to produce a shaped product.
Resins that have been used in the open bath and injection die methods of
pultrusion include thermoset resins, such as unsaturated polyesters, epoxies,
phenolics,
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methacrylates and the like, as well as thermoplastic resins such as PPS, ABS,
Nylon 6.
Blocked polyurethane prepolymers also have been used. Polyester and epoxy
resins are
generally slower reacting than polyisocyanate-based thermosets, such as
polyurethanes
and polyisocyanurates. In addition, the use of blocked polyurethane resins in
pultrusion
has the disadvantage of requiring deblocking of the isocyanate to form a
volatile by-
product. This creates environmental concerns and may cause unwanted
plasticization of
the cured resin.
One component resin systems that are used in pultrusion include thermoset
resins,
which cure through ethylenic unsaturation, such as unsaturated polyesters,
vinyl esters,
to (meth)acrylics, and the like. These types of resins generally require the
use of volatile
unsaturated monomers, such styrene and/or methyl methacrylate. As such, resins
of this
type emit volatile organic compounds (VOC's) during processing. Engineering
solutions
to the VOC issue, such as the use of closed injection dies, have had only
limited success
in controlling these emissions and the intense odors that they produce. The
monomers
used in the production of isocyanate-based resins are usually much less
volatile than the
unsaturated monomers. Accordingly, polyisocyanate-based resin systems have
some
inherent advantages. However, isocyanate-based formulations have had
difficulties due
to their relatively high reactivity at ambient temperatures.
Direct mixing activation has also been used to form polyisocyanate-based
matrix
2o polymers in the pultrusion process. Mixing activated systems of this type
generally
consist of a polyisocyanate component and an isocyanate reactive component
(see e.g.
WO 00/29459). The mixing activated systems disclosed in the prior art
generally have a
limited range of processability. This is due to the highly reactive nature of
the mixing
activated free isocyanate based chemistry. A careful balance needs to be
struck between
the demands of adequate mixing and fiber wetting, the achievement of
economically
effective line speeds, and the physical properties required in the final
pultruded composite
article. The ideal mixing activated resin system has a long open time (or pot
life) during
(and after) mixing at relatively low temperature, but is characterized by
rapid and even
cure at the higher temperatures used for resin curing in the pultrusion curing
die.
The ideal mixing activated resin system further provides for pultrusion
processing
at high line speeds. A significant drawback of prior art mixing activated
isocyanate-based
resin systems for use in pultrusion processing has been limited line speeds.
Prior art
systems of this type show surface defects and fouling of the processing
apparatus when
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processed at line speeds that are economically most interesting. The defects
that are
observed at these higher line speeds are sometimes referred to in the art as
"powdering"
or "sloughing". The onset of these phenomena, as a function of line speed,
vary with the
geometrical complexity of the pultruded profiles being made. It is not
possible to cite any
particular line speed at which these undesirable phenomena always appear.
However, it
is noted that more complex profiles are usually more challenging to process at
high line
speeds than simple (flat) profiles. For any given profile, the ability to
process at higher
line speed without surface defects or fouling is an advantage in terms of the
overall
process economics.
l0 A need therefore exists for mixing activated isocyanate-based resin
systems, such
as polyisocyanurate and polyurethane resin systems, that may be used in
pultrusion,
especially injection die pultrusion, which provide for a better combination of
long pot life
and fast cure and which can be processed at higher line speeds than prior art
systems
without powdering or sloughing.
Summary of the Invention
The invention provides a reaction system for the preparation of a fiber-
reinforced
composite according to the pultrusion process comprising:
(a) a reaction mixture formed by combining an isocyanate reactive composition
2o and a polyisocyanate composition,
(b) a continuous fiber reinforcing material, and
(c ) a catalyst composition;
wherein the catalyst composition contains a combination of at least two
different metals
in effective amounts, and wherein the combination of the reaction mixture and
the
catalyst composition (henceforth the "catalyzed reaction mixture") initially
contains both
free isocyanate groups and free alcoholic -OH groups, has a gel time of
greater than 768
seconds at 25°C, and a gel time of not greater than 120 seconds at
175°C.
The invention further provides an improved pultrusion process for preparing a
cured fiber reinforced polymer composite comprising the steps of:
(a) pulling continuous fibers through an impregnation die,
(b) supplying an isocyanate reactive composition, a catalyst composition, and
a
polyisocyanate composition to produce a catalyzed reaction mixture and
feeding the catalyzed reaction mixture to the impregnation die,
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(c) contacting the continuous fibers with the catalyzed reaction mixture in
the
impregnation die for a time period and at a temperature sufficient to cause
substantial polymerization of the catalyzed reaction mixture within the
impregnation die to produce a composite of fibers coated by the reaction
mixture,
(d) directing the composite of fibers coated by the reaction mixture through a
heated curing die to at least partially advance the cure of the catalyzed
reaction
mixture so as to produce a solid fiber reinforced polymer matrix, and
(e) drawing said solid composite from the curing die
1o wherein the catalyst composition contains a combination of at least two
different metals
in effective amounts, and wherein the mixture of the catalyst composition with
the
polyisocyanate composition and isocyanate reactive composition (henceforth the
"catalyzed reaction mixture") initially contains both free alcoholic -OH
groups and free
isocyanate (-NCO) groups, has a gel time of greater than 768 seconds at
25°C, and a gel
time of not greater than 120 seconds at 175°C.
The pultrusion reaction system and process according to the invention are
suitable
for operation at higher line speeds, without powdering or sloughing, than are
similar
systems/processes that do not employ the metal based catalyst composition
containing a
combination of at least two different metals in effective amounts. When the
comparison
2o is made on the same pultrusion line and with the same profile geometry
(curing die
geometry), the pultrusion reaction system and process disclosed herein
surprisingly
provides for operation at higher line speeds (prior to the onset of noticeably
increased part
surface defects or line fouling problems) than shown in the prior art.
The invention further provides a fiber reinforced solid composite prepared
according to the improved pultrusion process.
In preferred embodiments, the catalyzed reaction mixture has a gel time at
25°C of
greater than 900 seconds. In more preferred embodiments, the catalyzed
reaction mixture
has a gel time at 25°C of 1000 seconds or more. In still more highly
preferred
embodiments, the catalyzed reaction mixture has a gel time at 25°C in
the range of from
1000 seconds to 4000 seconds. In yet more highly preferred embodiments, the
catalyzed
reaction mixture has a gel time at 25°C in the range of from 1000
seconds to 3900
seconds, and a gel time at 175°C of less than 120 seconds.
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In other preferred embodiments, the catalyzed reaction mixture is always
substantially free of styrene or methyl methacrylate. In still other preferred
embodiments,
the catalyzed reaction mixture is substantially free of organic species, other
than carbon
dioxide, boiling lower than 200°C at 1 atmosphere pressure. In highly
preferred
embodiments, the catalyzed reaction mixture remains in a liquid and flowable
state, even
though partial reaction has occurred, after it has been applied to the
reinforcing fibers
until it reaches the curing die.
In a particularly preferred embodiment, the improved reaction system is free
of
tertiary amine catalysts.
to The preferred metal-based catalyst compositions comprise effective amounts
of at
least two different metals in organically bound form. The different metals may
be present
in the catalyzed reaction mixture together within a single organometallic
compound, in
separate organometallic compounds, or both. The metals themselves may be
present in
any or all of their available oxidation states, provided that they are
effective for the
catalysis of the cure of the reaction system under the conditions employed for
pultrusion
processing. The individual metals may be present as coordination complexes, as
covalent
compounds, as ionic compounds, or any combination thereof, provided that they
are
effective for the catalysis of the cure of the reaction system. The preferred
organometallic compounds are those that have sufficient solubility in the
polymer-
forming reaction mixture, under the conditions employed for pultrusion
processing, to be
effective in catalyzing the cure of the reaction system.
In the preferred embodiments, at least two of the metals present in the metal
based
catalyst composition are selected from the group consisting of any of the
metals of
Groups IIIB, IVB, VB, VIB, VIIB, VIIIB, IB, IA, IIA, IIIA, IVA, VA, VIA, the
Lanthanide series, and the Actinide series of the Periodic Table of the
Elements. In still
more preferred embodiments, at least two of the metals used in the catalyst
composition
are selected from among the group consisting of the metals of Groups IIIA,
IVA, and VA.
In even more preferred embodiments, at least two of the metals used in the
catalyst
composition are selected from the group consisting of Al, Ga, In, Ge, Sn, Sb,
and Bi. In
the most preferred embodiments, at least two of the metals used in the
catalyst
composition are selected from the group consisting of Al, Sn, and Bi.
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Detailed Description of the Invention
The invention provides a reaction system for the preparation of a fiber-
reinforced
composite according to the pultrusion process comprising:
(a) a reaction mixture comprising an isocyanate reactive composition and a
polyisocyanate composition,
(b) a continuous fiber reinforcing material, and
(c ) a catalyst composition;
wherein the catalyst composition contains a combination of at least two
different metals
in effective amounts, and wherein the combination of the reaction mixture and
the
catalyst composition (henceforth "catalyzed reaction mixture") initially
contains both free
isocyanate groups and free alcoholic -OH groups, has a gel time of greater
than 768
seconds at 25°C, and a gel time of less than 120 seconds at
175°C.
The invention further provides an improved pultrusion process for preparing a
cured fiber reinforced polymer composite comprising the steps of:
(a) pulling continuous fibers through an impregnation die while contacting the
fibers with a catalyzed reaction mixture comprising an isocyanate reactive
composition, a polyisocyanate composition, and a catalyst composition
sufficient to cause substantial polymerization of the catalyzed reaction
mixture
within the impregnation die to produce a composite of fibers coated by the
catalyzed reaction mixture, which is not~fully cured,
(b) directing the composite of fibers coated by the catalyzed reaction mixture
through a heated curing 'die to further advance the cure of the catalyzed
reaction mixture so as to produce a solid fiber reinforced composite, and
(c) withdrawing the solid fiber reinforced composite from the curing die;
wherein the catalyst composition contains a combination of at least two
different metals
in effective amounts, and wherein the catalyzed reaction mixture initially
contains both
free alcoholic -OH groups and free isocyanate (-NCO) groups, has a gel time of
greater
than 768 seconds at 25°C, and a gel time of less than 120 sec at
175°C.
The expressions "impregnation die", "inj ection die", "impregnation box", and
"injection box" are synonymous within the context of the specification.
The invention further provides an improved fiber reinforced solid composite
prepared according to the pultrusion process.
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In preferred embodiments, the catalyzed reaction mixture has a gel time at
25°C of
greater than 900 seconds. In more preferred embodiments, the catalyzed
reaction mixture
has a gel time at 25°C of 1000 seconds or more. In still more highly
preferred
embodiments, the catalyzed reaction mixture has a gel time at 25°C in
the range of from
1000 seconds to 4000 seconds. In yet more highly preferred embodiments, the
catalyzed
reaction mixture has a gel time at 25°C in the range of from 1000
seconds to 3900
seconds, and a gel time at 175°C of less than 120 seconds.
In other preferred embodiments, the catalyzed reaction mixture is always
substantially free of styrene or methyl methacrylate. In still other preferred
embodiments,
1o the catalyzed reaction mixture is substantially free of organic species,
other than carbon
dioxide, boiling lower than 180°C, more preferably free of species
boiling lower than
200°C, at 1 atmosphere pressure (760 mmHg). In highly preferred
embodiments, the
catalyzed reaction mixture remains in a liquid and flowable state, even though
partial
reaction has occurred, after it has been applied to the reinforcing fibers
until it reaches the
curing die.
WO 00/29459 provides bacl~ground information on pultrusion processing with
closed impregnation dies, and is incorporated herein fully by reference. Co-
pending U.S.
application serial number 10/626,983, filed July 25, 2003, provides further
information
and worl~ing examples of prior art reactive isocyanate-based pultrusion
reaction systems
2o and of processes using these systems. This co-pending application is also
incorporated
herein fully by reference.
Suitable isocyanate reactive compositions include compositions containing a
plurality of active hydrogen groups that are reactive towards organic
isocyanate groups
under the conditions of processing. The most preferred isocyanate reactive
compositions
are organic compounds, organic liquid polymers, or mixtures of such species
that each
individually contain a plurality of primary and/or secondary organically bound
alcoholic
hydroxyl groups. These polyhydroxy functional organic species (polyols) may
optionally
be used in combination with other binds of organic polyfunctional isocyanate-
reactive
species in formulating the isocyanate reactive composition. Preferred examples
of the
latter are polyamines, which contain primary and/or secondary amine groups. It
is within
the scope of the invention, however, to use isocyanate-reactive polyfunctional
organic
active hydrogen species other than polyols if these provide the desired
reaction profile in
derived mixing activated polymer-forming reaction systems. It is also within
the scope of
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the invention to employ active hydrogen species, which contain more than one
bind of
isocyanate-reactive active-hydrogen functional group. Preferred examples of
the latter
include aminoalcohols, which contain both isocyanate-reactive hydroxyl groups
and
isocyanate-reactive amino groups. Mixtures of different lands of
polyfunctional
isocyanate-reactive molecular species may, of course, be used in the
formulation of the
isocyanate reactive composition if desired. The isocyanate reactive functional
groups
present are preferably of the active hydrogen type. The isocyanate reactive
compositions
are all preferably liquids at 25°C. All polyfunctional isocyanate-
reactive molecular
species present in the reaction system (that are reactive towards organic
isocyanate groups
under the conditions of processing and are not themselves isocyanates) are, by
definition,
part of the isocyanate reactive composition. The term "polyfunctional" is
understood to
encompass molecular species bearing two or more isocyanate reactive functional
groups
(that are reactive towards organic isocyanates under the conditions of
processing and are
not themselves isocyanate groups). The isocyanate reactive composition
consists
essentially of one or a combination of these polyfunctional isocyanate
reactive molecular
species. The isocyanate reactive composition preferably contains less than 10%
by
weight, more preferably less than 5% by weight, still more preferably less
than 2% by
weight, and most preferably less than 1% by weight (of the total weight of the
isocyanate
reactive composition) of monofunctional isocyanate reactive molecular species,
present as
impurities. It is, ideally, devoid of such monofunctional species.
Monofunctional
isocyanate reactive species may be added to the reaction system deliberately,
as optional
additives. However, such additives (added intentionally) are, by definition,
outside the
definition of the isocyanate reactive composition (and within the definition
of optional
additives, as defined further hereinbelow).
This isocyanate reactive composition preferably comprises at least one organic
polyol, wherein said organic polyol has a number averaged functionality of
organically
bound primary or secondary alcohol groups of at least 1.8. The number averaged
functionality of said polyol is preferably from 1.8 to 10, more preferably
from 1.9 to 8,
still more preferably from 2 to 6, and most preferably from 2.3 to 4. More
preferably, the
isocyanate reactive composition consists predominantly, on a weight basis, of
a polyol or
mixture of polyols. Most preferably, the isocyanate reactive composition
consists
essentially of one or more polyols.
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In certain embodiments, the isocyanate reactive composition will preferably
comprise a mixture of two or more organic polyols. The individual polyols in
the mixture
will differ principally in regard to hydroxyl group functionality and
molecular weight. In
an embodiment of the invention, the organic polyols used in the isocyanate
reactive
composition are selected from the group consisting of softblock polyols, rigid
polyols,
chain extenders, crosslinkers, and combinations of these different types of
polyols.
Polyols, which furnish softblock segments, are known to those skilled in the
art as
softblock po~yols or as flexible polyols. Such polyols generally have a number
averaged
molecular weight of at least about 1500 (preferably from about 1750 to about
8000), a
to number averaged equivalent weight of from about 400 to about 4000
(preferably from
about 750 to 2500), and number averaged functionality of isocyanate reactive
organic -
OH groups of about 1.8 to about 10 (preferably from about 2 to about 4). Such
compounds include, for example, aliphatic polyether or aliphatic polyester
polyols
comprising primary and/or secondary hydroxyl groups. It is preferred that
these softblock
polyols comprise from about 0 to about 30% by weight, and more preferably,
from about
0 to about 20% by weight of the isocyanate reactive species present in the
active
hydrogen composition. Preferred softblock polyols are liquid at 25°C.
Polyols that provide structural rigidity in the derived polymer are referred
to in the
art as rigid polyols, and are a preferred class of polyols. Such polyols
generally have
2o number averaged molecular weights of from 250 to about 3000, preferably
from 250 to
less than 1500; number averaged equivalent weights of from 80 to about 750,
preferably
from 85 to about 300; and number averaged isocyanate reactive group
functionalities of
from 2 to 10, preferably 2 to 4, and more preferably 2 to 3. Such compounds
include, for
example, polyether or polyester polyols comprising primary and/or secondary
hydroxyl
groups. Preferred rigid polyols are liquid at 25°C.
Polyols that are referred to the in the art as chain extenders and/or
crosslinkers are
another preferred class of poyols. These have molecular weights between 60 to
less than
250 (preferably from 60 to about 150), equivalent weights from 30 to less than
100
(preferably 30 to 70), and isocyanate-reactive group functionalities of from 2
to 4
(preferably from 2 to 3).
Examples of suitable chain-extenders/crosslinkers are simple glycols and
triols,
such as ethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol,
1,3-
butanediol, triethanolamine, triisopropanolamine, tripropylene glycol,
diethylene glycol,
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triethylene glycol, glycerol, mixtures of these, and the like. The most
preferred chain-
extenders/crosslinkers are liquids at 25°C. Although aliphatic -OH
functional
compounds, such as those just listed, are the most preferred as chain-
extenders/crosslinkers, it is accetpable to employ certain isocyanate-reactive
polyamines,
polyamine derivatives, and/or polyphenols. Examples of suitable isocyanate-
reactive
amines known in the art include diisopropanolamine, diethanolamine, and 3,5-
diethyl-
2,4-diaminotoluene, 3,5-diethyl-2,6-diaminotoluene, mixtures of these, and the
like.
Examples of suitable isocyanate reactive amine derivatives include certain
imino-
functional compounds such as those described in European Patent Application
Nos.
l0 284,253 and 359,456 and certain enamino-functional compounds such as those
described
in European Patent Application No. 359,456 having 2 or more isocyanate-
reactive groups
per molecule. Reactive amines, especially aliphatic primary amines, are less
preferred
due to their extremely high reactivity with polyisocyanates, but may
optionally be used if
desired in minor amounts.
It is also acceptable, albeit less preferred, to include within the polyol
composition
minor amounts of other types of isocyanate reactive species that may not
conform to the
types described hereinabove.
The term "chain extender" is used in the art to refer to difunctional low
molecular
weight isocyanate reactive species, whereas the term "crosslinker" is limited
to low
2o molecular weight isocyanate reactive species having a functionality of 3 or
more.
In one embodiment, a preferred isocyanate reactive composition comprises a
mixture of (a) about 0 to 20% by weight of at least one polyol having a
molecular weight
of 1500 or greater and a functionality of 2 to 4, (b) about 60 to 100% by
weight of at least
one polyol having a molecular weight between 250 and 750 and a functionality
of about 3
to about 4, most preferably about 3, and (c) about 2 to about 30% by weight of
a least one
polyol having a functionality of about 2 to about 3 and a molecular weight of
less than
200, more preferably less than 150. The weights of (a) + (b) + (c) total 100%
of the
isocyanate reactive composition in this preferred isocyanate reactive
composition for two
component mixing activated pultrusion. All the polyol species in this
preferred mixed
isocyanate reactive composition contain essentially all primary and/or
secondary
aliphatically bound organic -OH groups.
In another embodiment, the isocyanate reactive composition comprises a total
of
at least 10% by weight, relative to the total weight of the isocyanate
reactive composition,
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of at least one hydrophobic polyol selected from the group consisting of
hydrocarbon
bacl~bone polyols of number averaged molecular weight greater than 500, fatty
ester
polyols of number averaged molecular weight greater than 500, and fatty
polyester
polyols of number averaged molecular weight greater than 500. A particularly
preferred
class of the fatty polyester polyols are those having number averaged
functionalities of
organically bound isocyanate-reactive hydroxyl groups of greater than 2. An
especially
preferred, but non-limiting, example of this class of fatty polyester polyols
is castor oil.
All the polyol species in these preferred isocyanate reactive compositions,
according to
this embodiment, contain essentially all primary andlor secondary
aliphatically bound
l0 organic -OH groups. Fatty ester (and fatty polyester) polyols are defined
further, in
greater detail, herein.
In yet another embodiment, the polyisocyanate composition may contain
isoCyanate-terminated prepolymers of one or more of the hydrophobic polyols
cited
hereinabove. In the more preferred modes of this embodiment, the
polyisocyanate
composition comprises a total of at least 5% by weight, relative to the total
weight of said
polyisocyanate composition, of the at least one isocyanate terminated
prepolymer of a
hydrophobic polyol. In the most preferred modes of this prepolymer embodiment,
the
polyisocyanate composition additionally contains some unreacted monomeric
polyisocyanate species. Polyisocyanate compositions comprising isocyanate
terminated
prepolymers of castor oil are especially preferred in this embodiment.
The incorporation of hydrophobic polyols, as listed above, into either the
isocyanate reactive composition, the polyisocyanate composition (as isocyanate
terminated prepolymers), or both has the effect of reducing or eliminating
unwanted
foaming during processing of the reaction system into composite articles. This
provides
one, although not the only, means for reducing foaming during processing.
Another technique for inhibiting foaming during processing is to eliminate the
use
of tertiary amine species from the reaction system. Aliphatic tertiary amines
are
particularly problematic in this regard.
It is to be understood unless otherwise stated that all functionalities,
molecular
3o weights, and equivalent weights described herein with respect to polymeric
materials are
number averaged, and that all functionalities, molecular weights, and
equivalent weights
described with respect to pure compounds are absolute.
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Some preferred types of polyols include the polyether polyols and the
polyester
polyols. Suitable polyether polyols that can be employed in the reaction
systems of the
invention include those that are prepared by reacting .an alkylene oxide, a
halogen
substituted or aromatic substituted alkylene oxide or mixtures thereof, with
an active
hydrogen containing initiator compound.
Suitable oxides include for example ethylene oxide, propylene oxide, 1,2-
butylene
oxide, styrene oxide, epichlorohydrin, epibromohydrin, mixtures thereof, and
the like.
Propylene oxide and ethylene oxide are particularly preferred alkylene oxides.
Suitable initiator compounds include water, ethylene glycol, propylene glycol,
l0 butane diols, hexanediols, glycerine, trimethylolpropane,
trimethylolethane,
pentaerythritol, hexanetriols, sucrose, hydroquinone, resorcinol, catechol,
bisphenols,
novolac resins, phosphoric acid, and mixtures of these.
Further examples of suitable initiators include ammonia, ethylenediamine,
diaminopropanes, diaminobutanes, diaminopentanes, diaminohexanes,
diethylenetriamine, triethylenetetramine, tetraethylenepentamine,
pentamethylenehexamine, ethanolamine, aminoethylethanolamine, aniline, 2,4-
toluenediamine, 2,6-toluenediamine, 2,4'-diaminodiphenylmethane, 4,4'-
diaminodiphenylmethane, 1,3-phenylenediamine, 1,4-phenylenediamine,
naphthylene-
1,5-diamine, triphenylmethane-4,4',4"-tramine, 4,4'-di-(methylamino)-
diphenylmethane,
1,3-diethyl-2,4-diaminobenzene, 2,4-diaminomesitylene, 1-methyl-3,5-diethyl-
2,4-
diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5-triethyl-2,6-
diaminobenzene, 3,5,3',5'-tetraethyl-4,4'-diamiodiphenylmethane, and amine
aldehyde
condensation products such as the crude polyphenylpolymethylene polyamine
mixtures
produced from aniline and formaldehyde, and mixtures thereof.
Suitable polyester polyols include, for example, those prepared by reacting a
polycarboxylic acid or anhydride with a polyhydric alcohol. The polycarboxylic
acids
may be aliphatic, cycloaliphatic, araliphatic, aromatic, and/or heterocyclic
and may be
substituted (e.g. with halogen atoms) and/or unsaturated: Examples of suitable
carboxylic
acids and anhydrides include succinic acid; adipic acid; suberic acid; azelaic
acid; sebacic
acid; pthtalic acid; isophthalic acid; terephthalic acid; trimellitic acid;
phthalic anhydride;
tetrahydrophthalic anhydride; hexahydrophthalic anhydride; tetrachlorophthalic
anhydride; endomethylene tetrahydrophthalic anhydride; glutaric acid
anhydride; malefic
acid; malefic anhydride; fumaric acid; dimeric and trimeric fatty acids, such
as those
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obtained from oleic acid, which may be in admixture with monomeric fatty
acids. Simple
esters of polycarboxylic acids may also be used in preparing polyester
polyols. For
example, terephthalic acid dimethyl ester, terephthalic acid bis glycol
esters, and mixtures
of these. Examples of polyhydric alcohols suitable for use in preparing
polyester polyols
include ethylene glycol; 1,3-, 1,4-, 1,2-, and 2,3-butanediols; 1,6-
hexanediol; 1,8-
octanediol; neopentyl glycol; cyclohexane dimethanol (1,4-bis-hydroxymethyl
cyclohexane); 2-methyl-1,3-propanediol; glycerol; mannitiol; sorbitol;
methylglucoside;
diethylene glycol; trimethylolpropane; 1,2,6-hexanetriol; 1,2,4-butanetriol;
trimethylolethane; pentaerythritol; triethylene glycol; tetraethylene glycol;
polyethylene
l0 glycols; dipropylene glycol; tripropylene glycol; polypropylene glycols;
dibutylene
glycol; polybutylene glycols; mixtures of these; and the life. The polyester
polyols may
optionally contain some terminal carboxy groups although preferably they are
fully
hydroxyl terminated. It is also possible to use polyesters derived from
lactones such as
caprolactone; or from hydroxy carboxylic acids such as hydroxy caproic acid or
hydroxyacetic acid. A particularly preferred class of polyester polyols are
the fatty
polyester polyols derived from natural sources, such as castor oil and the
like.
A non-limiting example of a preferred isocyanate reactive polyol suitable for
use
in the invention is a propylene oxide adduct of glycerol having a nominal
functionality of
3 and a number-averaged hydroxyl equivalent weight of 86. This predominantly
2o secondary-OH functional triol is an example of a rigid polyol, as per the
description
provided hereinabove. It is commercially available from Huntsman Petrochemical
Corporation as JEFFOL~ G 30-650 polyol. Another preferred isocyanate reactive
polyol
suitable for use in the invention is a propylene oxide adduct of glycerol
having a nominal
functionality of 3 and a number-averaged hydroxyl equivalent weight of about
234. This
predominantly secondary-OH functional triol is another example of a rigid
polyol, as per
the description hereinabove. This polyol is also available from Huntsman
Petrochemical
Corporation as JEFFOL~ G 30-240 polyol. Blends of JEFFOL~ G 30-650 polyol with
JEFFOL~ G 30-240 polyol are examples of a preferred polyol mixture. The
preferred
weight ratios of these two polyols in these preferred blends are from about
1:2 to about
2:1.
Examples of particularly preferred crosslinkers suitable for use in the
isocyanate
reactive composition include glycerol, trimethylolpropane, and mixtures of
these.
Glycerol is especially preferred.
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Examples of particularly preferred chain extenders suitable for use in the
isocyanate reactive composition include ethylene glycol, diethylene glycol,
triethylene
glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and
mixtures of these.
Dipropylene glycol, diethylene glycol, and mixtures of these two glycols are
especially
preferred. Combinations of both chain extenders and crosslinkers may, if
desired, be used
in the same isocyanate reactive composition.
Examples of preferred optional flexible polyols that may be used in the
isocyanate
reactive compositions include polyether polyols of molecular weight 2000 or
greater. An
example of a preferred flexible polyether polyol suitable for use is JEFFOL~ G
31-55
1o polyol, which is a nominal polyether triol commercially available from
Huntsman
Petrochemical Corporation. JEFFOL~ G 31-55 polyol has an hydroxyl equivalent
weight of about 1000, and is prepared from a combination of propylene oxide
and
ethylene oxide. An example of another preferred flexible polyol that may be
used in the
polyol compositions suitable for the invention is JEFFOL~ G 31-35 polyol. This
polyol,
which is also prepared from propylene oxide and ethylene oxide, is a nominal
polyether
triol commercially available from Huntsman Petrochemical Corporation. JEFFOL~
G
31-35 polyol has a hydroxyl equivalent weight of about 1600. A preferred class
of
flexible polyols contain predominantly primary -OH groups. The flexible
polyols are
preferably used at levels of 20% by weight or less of the total isocyanate
reactive
2o composition, but may be used at higher levels if desired. It is within the
scope hereof to
produce relatively flexible pultruded composites by using predominantly
flexible polyols
in the isocyanate reactive composition. However, it is much more typical to
produce rigid
pultruded composites by using predominantly or exclusively rigid polyols, or
combinations of rigid polyols with chain extenders andlor crosslinl~ers, in
the isocyanate
reactive composition.
Other examples of rigid polyols suitable for use include rigid polyether
polyols
produced from an initiator composition that comprises one or more sugars. A
specific
example of a suitable rigid polyol of this type is JEFFOL~ SD-441 polyol,
which is
commercially available from Huntsman Petrochemical Corporation. JEFFOL~ SD-441
3o polyol is prepared by propoxylation of a mixture of sucrose and a glycol,
and has a
number averaged equivalent weight of about 128.
The term "nominal functionality" applied to polyols, as used in the context of
this
invention, denotes the expected functionality of the polyol based upon the raw
materials
14
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WO 2005/049301 PCT/US2004/038118
used in its synthesis. The nominal 'functionality may differ slightly form
actual
functionality, but the difference may usually be ignored in the context of
this invention.
The nominal functionality of a polyoxyalkylene polyether polyol is the
functionality of
the initiator. This is particularly true for polyether polyols, which are
based
predominantly on EO and/or PO (such as, for example, the JEFFOL~ G 30-650
polyol,
described above). The nominal functionality of a pure compound is, of course,
the same
as its absolute functionality. If a mixed initiator is used, then the nominal
functionality of
the polyol is the number averaged functionality of the mixed initiator.
A class of ester-group-containing polyols suitable for use in the isocyanate
to reactive composition are the fatty ester (and fatty polyester) polyols.
Fatty ester (and
fatty polyester) polyols comprise at least one alkyl or alkenyl (hydrocarbon)
side chain of
from 4 to about 50 carbon atoms, preferably 5 to 25 carbon atoms, more
preferably 6 to
20 carbon atoms, and most preferably 6 to less than 15 carbon atoms. The alkyl
side
chains are the more preferred. The fatty ester (and fatty polyester) polyols
also comprise
at least two primary or secondary aliphatic -OH groups per molecule and
preferably
greater than 2 up to 4 such -OH groups. The fatty ester polyols contain one
carboxylic
ester linkages per molecule. The fatty polyester polyols contain at least two
carboxylic
ester linkages per molecule. The fatty polyester polyols are more preferred.
Preferred
examples of fatty polyester polyols are those that contain at least one
triglyceride
2o structure and are liquid at 25°C. The fatty ester (and fatty
polyester) polyols should
preferably be free of aromatic rings, although it would be within the scope of
the
invention to use fatty ester (and fatty polyester) polyols that contain such
rings. The fatty
(poly)ester polyol may optionally contain ether linlcages. A particularly
preferred but
non-limiting example of a triglyceride based fatty polyester polyol is castor
oil. Mixtures
of different fatty (poly)ester polyols may be used if desired. The fatty
(poly)ester polyol
may be used by itself, but is preferably used in combination with at least one
other type of
polyol. The fatty (poly)ester polyol is most preferably used in combination
with one or
more polyether polyols. A preferred range of weight ratios of fatty
(poly)ester polyols to
polyether polyols, in the isocyanate reactive composition, is from about 1:9
to about 9:1,
3o and more preferably from 1:4 to 4:1. The fatty (poly)ester polyols have the
desired effect
of reducing foaming of the catalyzed reaction mixture during processing and
curing,
although this is not the only means for reducing foaming. The fatty
(poly)ester polyols,
and castor oil in particular, appear surprisingly more effective at reducing
foaming than
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conventional drying agents (such as molecular sieves) or conventional
defoaming agents
(such as silicone based antifoam additives). Although not wishing to be bound
by theory,
it is believed that the beneficial effects of the fatty (poly)ester polyols in
reducing
unwanted foaming (when foaming is present) is due to their hydrophobic nature.
Other
hydrophobic polyols, and/or optional additives, that might be exploited for
this beneficial
(antifoaming) effect, when needed, include hydrocarbon backbone polyols such
as the
polybutadiene-based polyols, polyisoprene based polyols; hydrogenation
products
thereof; as well as simple aromatic or aliphatic oils. The optional, but
preferred,
hydrophobic polyols may also be incorporated into the polyisocyanate
composition. It is,
for example, possible to include prepolymers of fatty (poly)ester or
polybutadiene polyols
into the polyisocyanate composition.
The isocyanate reactive composition is the predominant isocyanate reactive
material (other than the organic polyisocyanate itself) in the mixing
activated chemical
formulation used in the invention. This isocyanate reactive composition is,
most
preferably, a polyol or a blend of polyols. Preferably, this isocyanate
reactive
composition constitutes at least 90% by weight, more preferably at least 95%
by weight,
and most preferably at least 98% by weight of the combined isocyanate reactive
species
(other than the organic polyisocyanate itself) present in the chemical
formulation used in
the present invention. Preferably, non-active hydrogen functional isocyanate-
reactive
resins, such as epoxy resins, are substantiallyabsent from the chemical
formulation. By
"substantially free" it is meant that the reaction mixture contains less than
10% by weight
of all such non-active-hydrogen functional isocyanate-reactive resins
combined, relative
to the total weight of the catalyzed reaction mixture (including all
catalysts, and optional
additives that may be present). More preferably, the catalyzed reaction
mixture contains
less than 5% by weight of all such species combined, relative to the total
weight of the
catalyzed reaction system. Still more preferably, the catalyzed reaction
mixture contains
less than 2% by weight of such species, even more preferably less than 1%,
most
preferably less than 0.5%, and ideally less than 0.1%, relative to the total
weight of the
catalyzed reaction mixture.
In an alternate embodiment, the isocyanate reactive composition may be admixed
with minor amounts of water by weight. The water, when used, functions as a
foaming
agent. In the more preferred embodiments, the chemical formulation used in the
process
(including the isocyanate reactive composition, polyisocyanate composition,
catalysts,
16
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WO 2005/049301 PCT/US2004/038118
and any optional additives that may be present) is essentially free of water,
or any other
foam generating species. Preferably, the chemical formulation (including the
isocyanate
reactive composition, polyisocyanate composition, the required catalyst
composition, and
any optional additives that may be present) contains less than 0.2% by weight
of water or
other foam generating species, relative to the total formulation weight. Still
more
preferably, this chemical formulation contains less than 0.1% by weight, and
yet more
preferably less than 0.05% by weight of water or other foam generating
species, relative
to the total formulation weight. Ideally, both the chemical formulation used
to form the
catalyzed reaction mixture and the entire reaction system (including the
fibrous
l0 reinforcing material) should be devoid of water and other foam generating
species. The
phrase "foam generating species" is understood to encompass both chemical
blowing
agents, which produce a volatile blowing agent under the conditions of
processing by
means of a chemical reaction, as well as physical blowing agents (i.e.
entrained
atmospheric gases, or volatile organic or inorganic compounds that simply boil
under the
conditions of processing). The fiber reinforced pultruded composite articles
made from
the reaction system and according to the process of the invention are most
preferably
solid, and not foamed or cellular.
The polyisocyanate composition preferably consists of organic polyisocyanates
having a number averaged isocyanate (-NCO) functionality of from at least 1.8
to about
4Ø In the more preferred embodiments, the number averaged isocyanate
functionality of
the polyisocyanate composition is preferably from 2.0 to about 3.0, more
preferably from
2.3 to 2.9.
The polyisocyanate composition preferably has a free isocyanate group content
(
NCO content) in the range of from 5% to 50% by weight, but more preferably in
the
range of from 7% to 45%, still more preferably in the range of from 8% to 40%,
yet more
preferably in the range of from 9% to 35%, and most preferably in the range of
from 10%
to 33.6% by weight.
The expression "organic polyisocyanate" will be understood to encompass
isocyanate molecular species having a plurality of organically bound free
isocyanate (
NCO) groups. This definition includes organic diisocyanates, triisocyanates,
higher
functionality polyisocyanates, and mixtures thereof.
The polyisocyanates that may be used in the polyisocyanate composition in the
preferred embodiments of present invention include any of the aliphatic,
cycloaliphatic,
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araliphatic, or aromatic polyisocyanates known to those spilled in the art.
Especially
preferred are those polyisocyanates that are liquid at 25°C. Examples
of suitable
polyisocyanates include 1,6-hexamethylenediisocyanate, isophorone
diisocyanate, 1,4-
cyclohexane diisocyanate, 4,4'-dicyclohexyhnethane diisocyanate, 1,4-xylylene
diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-
toluene
diisocyanate, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-
diphenylmethane
diisocyanate (2,4'-MDI), polymethylene polyphenylene polyisocyanates (crude,
or
polymeric, MDI), and 1,5-naphthalene diisocyanate. Mixtures of these
polyisocyanates
can also be used. Moreover, isocyanate-functional polyisocyanate variants, for
example,
1o polyisocyanates that have been modified by the introduction of urethane,
allophanate,
urea, biuret, carbodiimide, uretonimine, isocyanurate, and/or oxazolidone
residues can
also be used.
In general, aromatic polyisocyanates are more preferred. The most preferred
aromatic polyisocyanates are 4,4'-MDI, 2,4'-MDI, polymeric MDI, MDI variants
(defined to encompass isocyanate terminated prepolymers), and mixtures of
these. This
most preferred class of aromatic polyisocyanates will be collectively referred
to as the
"MDI series" of polyisocyanates.
Isocyanate terminated prepolymers may optionally be employed. Such
prepolymers are generally prepared by reacting a molar excess of polymeric or
pure
2o polyisocyanate with one or more polyols. The polyols may include aminated
polyols,
imine or enamine modified polyols, polyether polyols, polyester polyols or
polyamines.
Pseudoprepolymers (also known as semiprepolymers or quasiprepolymers), that
are
mixtures of an isocyanate terminated prepolymer and one or more monomeric
polyisocyanates, may also be used. The use of prepolymers and especially
pseudoprepolymers is one preferred optional method for modifying the
mechanical
properties of the matrix resin. The use of prepolymers and pseudoprepolymers
is also a
useful technique for control of the weight ratios of the reactive components
during mixing
activated two-component pultrusion processing.
Although it is within the scope of the invention to incorporate
polyisocyanates that
3o are fully or partially blocked, it is much more preferable not to use any
blocped
isocyanate species. Free isocyanate (-NCO) groups are strongly preferred.
Consequently,
the polyisocyanate should be essentially free of blocked isocyanate groups.
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Commercially available polyisocyanates useful in the preferred two-component
isocyanate-based pultrusion process include the RUBINATE~ and SUPRASEC~ brand
polymeric isocyanates available from Huntsman International LLC. A specific
example
of a preferred polyisocyanate composition particularly suitable for use in the
invention is
SUPRASEC~ 9700 polyisocyanate. This liquid isocyanate is of the polymeric MDI
type
and has a free isocyanate (-NCO) group content of 31.5% by weight and a number
averaged isocyanate group functionality of 2.7. This polyisocyanate is
commercially
available from Huntsman International LLC. Another specific example of a
preferred
polyisocyanate composition suitable for use in certain embodiments of the
invention is
to RUBINATE~ 1790 polyisocyanate. This product, which is commercially
available from
Huntsman International LLC, is a urethane modified pure 4,4'-MDI product that
has a
number averaged isocyanate group functionality of about 2.00 and has a free
isocyanate
(-NCO) group content of about 23% by weight.
The catalyzed reaction mixture contains a catalyst composition for catalyzing
one
or more of the polymer forming reactions of polyisocyanates. The catalysts)
are
preferably introduced into the reaction mixture by pre-mixing with the
isocyanate reactive
composition (i.e. the polyol blend). The catalyzed reaction mixture, in this
preferred
embodiment, results when the pre-formed mixture of the isocyanate reactive
composition
with the catalyst composition is combined with the polyisocyanate composition.
2o It is a defining feature of the invention that the reaction system must
contain a
catalyst composition that comprises at least two different metals in
catalytically effective
amounts. The metals are preferably incorporated into one or more
organometallic
compounds that are sufficiently soluble in the reaction mixture to provide for
effective
catalytic activity under the conditions of pultrusion processing. The catalyst
composition
preferably contains at least two different metals selected from the group
consisting of the
metals of Groups IIIA, IVA, and VA of the Periodic Table of the Elements. In
the most
preferred embodiments of the invention, the catalyst composition contains at
least two
different metals selected from the group consisting of aluminum, tin, and
bismuth.
Although not essential, it is acceptable to include additional metals in the
catalyst
3o composition. It is also possible to include non-metal catalysts in the
catalyst composition.
Examples of non-metallic catalysts, suitable for promoting polymer-forming
reactions of
polyisocyanates, are tertiary amines. It is within the broader scope of the
invention to use
tertiary amines as optional additional catalysts. However, in a highly
preferred
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WO 2005/049301 PCT/US2004/038118
embodiment of the invention, no aliphatic tertiary amine catalysts or salts
thereof are used
in the reaction system. In this preferred embodiment, it is possible to employ
aromatic
tertiary amines, such as aromatic amine initiated polyols. However, it is most
preferable
to exclude aliphatic tertiary amine species from the reaction system. In
another highly
preferred embodiment, the reaction system is free of both aliphatic and
aromatic tertiary
amine species or salts thereof. For the purposes of this specification, an
aliphatic tertiary
amine is a tertiary amine in which the tertiary nitrogen atom is bonded only
to aliphatic
carbon atoms. An aromatic tertiary amine is a tertiary amine in which the
tertiary
nitrogen atom is bonded to at least one aromatic carbon atom.
to Optional additional catalysts for the polymer forming reactions of organic
polyisocyanates are well known. The optional additional catalyst package may
consist of
a single catalyst, or a mixture of two or more catalysts, which are different
from those
required herein. "Some examples of optional additional catalysts are selected
from the
group consisting of tertiary amines and tertiary amine acid salts. Examples of
tertiary
amine catalysts that may optionally be used in the reaction system include
triethylenediamine, N,N-dimethyl cyclohexylamine, bis-(dimethylamino)-diethyl
ether,
N-ethyl morpholine, N,N,N',N',N"-pentamethyl diethylenetriamine, N,N-dimethyl
aminopropylamine, N-benzyl dimethylamine, and aliphatic tertiary amine-
containing
amides of carboxylic acids, such as the amides of N,N-dimethyl
aminopropylamine with
2o stearic acid, oleic acid, hydroxystearic acid, and dihydroxylstearic acid.
Commercially
available tertiary amine catalysts include the JEFFCAT~ brand catalysts from
Huntsman
Petrochemical Corporation and the POLYCAT~ and the DABCO~ amine catalysts,
both
available form Air Products and Chemicals Inc.
Examples of suitable tertiary amine acid salt catalysts which may optionally
be
used include those prepared by the at least partial neutralization of formic
acid, acetic
acid, 2-ethyl hexanoic acid, oleic acid, or oligomerized oleic acid with a
tertiary amine
such as triethylenediamine, triethanolamine, triisopropanolamine, N-methyl
diethanolamine, N,N-dimethyl ethanolamine, mixtures of these amines, or the
like. These
amine salt catalysts are sometimes referred to as "blocked amine catalysts",
owing to
3o delayed onset of catalytic activity that provides for improved convenience
of resin
application.
The catalyst composition must contain at least two different catalytically
active
metals in effective amounts. These metals should preferably be selected from
the group
CA 02544326 2006-05-O1
WO 2005/049301 PCT/US2004/038118
consisting of the metals of Groups IIIB, IVB, VB, V1B, VI1B, VIIIB, IB, IA,
ITA, IIIA,
IVA, VA, VIA, the Lanthanide series, and the Actinide series of the Periodic
Table of the
Elements. Optional additional metal catalysts containing metals from outside
these
groups may be used in the catalyst composition if desired, but only in
addition to the
required metal catalysts) according to the invention. The most preferred
catalyst
compositions according to the invention comprise catalytically effective
amounts of at
least two metals selected from the group consisting of aluminum, tin, and
bismuth.
Examples of some optional additional organometal compounds for possible use as
supplementary (optional) catalysts within the catalyst composition of the
reaction system
to include potassium 2-ethyl hexanoate (potassium "octoate"), potassium
oleate, potassium
acetate, calcium oleate, potassium hydroxide, zinc neodecanoate, zinc laurate,
zinc oleate,
and zinc stearate.
Further examples of optional additional catalysts suitable for use within the
catalyst composition of the reaction system include amido amine compounds
derived
from the amidization reaction of N,N-dimethyl propanedimine with fatty
carboxylic
acids. A specific example of such a catalyst is BUSPERSE 47 catalyst from
Buckman
Laboratories.
Mixtures of optional tertiary amine, optional amine acid salt, and optional
additional organo-metal catalysts may possibly be used within~the catalyst
composition.
It is sometimes desirable to include in the mixing activated chemical
formulation
one or more optional additional catalysts for the trimerization of isocyanate
groups.
Preferred examples of these optional additional catalysts include the all~ali
metal salts' of
carboxylic acids. Some specific examples of optional isocyanate trimerization
(isocyanurate) catalysts include potassium 2-ethyl hexanoate, potassium
oleate, potassium
acetate, and potassium hydroxide. These compounds are also ~ effective as
optional
additional catalysts for the reaction of polyisocyanates with active hydrogen
compositions
such as polyols.
The organo-metal compounds used in the catalyst composition, and any optional
catalysts that might also be used in the catalyst composition, regardless of
their specific
3o structure or function in the formulation, should preferably be non-volatile
species. The
more preferred catalysts therefore are those having boiling points above
200°C (at 1
atmosphere pressure), still more preferably above 250°C, and most
preferably above
260°C (at 1 atmosphere pressure).
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The most preferred catalyst compositions contain at least two separate
organometallic compounds, based on at least two different metals selected from
the group
consisting of aluminum, tin, and bismuth. The organometallic compounds are
preferably
soluble in the isocyanate-reactive composition at the levels required for
effective use in
pultrusion processing. Examples of suitable classes of organometallic
compounds
include metal carboxylates of the three metals mentioned above, and
acetoacetates of
these metals. These examples are not to be construed as limiting.
The levels of the preferred catalysts required to achieve the needed
reactivity
profile for pultrusion processing will vary with the composition of the
reaction system
l0 and must be optimized for each reaction system. Such optimization would be
well
understood by persons of ordinary shill in the art of polyisocyanate-based
polymer
chemistry. The catalysts preferably have at least some degree of solubility in
the
isocyanate-reactive compositions (polyol blends) used, and are most preferably
fully
soluble in the polyol blend at the use levels required.
In the preferred embodiments, each of the at least two required metals is
present in
the catalyzed reaction mixture as a soluble organometallic compound and each
of these
organometallic compounds is present at a concentration of greater than 0.0001%
by
weight, more preferably at least 0.001%, and still more preferably at least
0.005% by
weight, relative to the total weight of the catalyzed reaction mixture.
In the preferred embodiments each of the at least two required metals is
present in
the form of a separate organometallic compound.
The required metals may be present in any available oxidation state(s), or any
desired combination of oxidation states, provided that the oxidation states
chosen offer
effective catalytic activity for the cure of the reaction system under the
conditions
2s selected for pultrusion processing.
Each of the at least two required metals my optionally be present together in
a
single organometallic compound. In this unusual situation the mixed metal
compound
should be present in the catalyzed reaction mixture at a concentration of
greater than
i
0.0001%, preferably at least 0.001%, and more preferably at least 0.005% by
weight,
relative to the total weight of the catalyzed reaction mixture.-
The chemical precursors used to form the catalyzed reaction mixture may
contain
other optional additives if desired.
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The catalyst composition and the optional additives are typically added to the
isocyanate reactive composition (typically, this is a polyol blend) prior to
processing,
although it is within the scope of the invention to premix all or any part of
the catalysts
and the optional additives package with the polyisocyanate composition under
the proviso
that it does cause the polyisocyanate to self react or otherwise interfere
with pultrusion
processing of the reaction system.
Non limiting examples of additional optional additives include particulate or
short
fiber fillers, internal mold release agents, fire retardants, smoke
suppressants, dyes,
pigments, antistatic agents, antioxidants, UV stabilizers, minor amounts of
viscosity
to reducing inert diluents (preferably those boiling above 180°C at 760
mmHg pressure,
most preferably those boiling above 260°C at 760 mmHg pressure),
combinations of
these, and any other known additives from the art of polyisocyanate based
polymer
chemistry. In an alternative embodiment, the additives or portions thereof may
be
provided to the reinforcing fibers of the reaction system, such as by coating
the fibrous
reinforcing material with the additive.
Suitable fillers can include, for example, calcium carbonate, barium sulfate,
clays,
aluminium trihydrate, antimony oxide, milled glass fibers, wollastonite, talc,
mica, flaked
glass, silica, titanium dioxide, molecular sieves, micronized polyethylene,
combinations
of these, and the like. -
2o Internal mold release additives are highly preferred in pultrusion of
mixing
activated isocyanate based reaction systems in order to prevent sticking or
buildup in the
die. Suitable internal mold release agents may include, for example, fatty
amides such as
erucamide or stearamide, fatty acids such a oleic acid, oleic acid amides,
fatty esters such
as LOXIOL G71 S inert polyester (from Henkel), carnuba wax, beeswax (natural
esters),
butyl stearate, octyl stearate, ethylene glycol monostearate, ethylene glycol
distearate,
glycerin di-oleate, glycerin tri-oleate, and esters of polycarboxylic acids
with long chain
aliphatic monovalent alcohols such as dioctyl sebacate, mixtures of (a) mixed
esters of
aliphatic polyols, dicarboxylic acids and long-chained aliphatic
monocarboxylic acids,
and (b) esters of the groups: (1) esters of dicarboxylic acids and long-
chained aliphatic
3o monofunctional alcohols, (2) esters of long-chained aliphatic
monofunctional alcohols
and long-chained aliphatic monofunctional carboxylic acids, (3) complete or
partial esters
of aliphatic polyols and long-chained aliphatic monocarboxylic acids,
silicones such as
TEGO~ IIVVIR 412T silicone (from Goldschmidt), I~EMESTER~ 5721 ester (a fatty
acid
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WO 2005/049301 PCT/US2004/038118
ester product from Witco Corporation), fatty acid metal carboxylates such as
zinc stearate
and calcium stearate, waxes such as montan wax and chlorinated waxes, fluorine
containing compounds such as polytetrafluoroethylene, fatty alkyl phosphates
(both
acidic and non acidic types) which are known in the art, chlorinated-alkyl
phosphates;
hydrocarbon oils, combinations of these, and the like.
Other preferred optional additives for use in pultrusion processing of mixing
activated isocyanate-based polymer systems include moisture scavengers, such
as
molecular sieves; defoamers, such as polydimethylsiloxanes; coupling agents,
such as the
mono-oxirane or organo-amine functional trialkoxysilanes; combinations of
these and the
to like. The coupling agents are particularly preferred for improving the
bonding of the
matrix resin to the fiber reinforcement in the final pultruded composite. Fine
particulate
fillers, such as clays and fine silicas, are often used at thixotropic
additives. Such
particulate fillers may also serve as extenders to reduce resin usage.
Fire retardants are sometimes used as additives in pultruded composites.
Examples of preferred optional fire retardant categories include but are not
limited to
triaryl phosphates; trialkyl phophates, especially those bearing halogens;
melamine (as
filler); melamine resins (in minor amounts); halogenated paraffins;
combinations of these;
and the like. Other optional additives that may be used will be apparent to
those spilled in
the art.
2o In preferred embodiments, the ratio of the combined weight of all the
optional
additives in the entire chemical formulation, precursor to the catalyzed
reaction mixture,
to the combined weights of the isocyanate reactive composition (in isolation
from any
additives) and polyisocyanate composition (in isolation from any additives) is
less than 1,
more preferably less than 0.5, still more preferably less than 0.25, yet more
preferably
less than 0.1, and most preferably less than 0.07.
The stoichiometry of mixing activated isocyanate-based polymer forming
formulations, containing an organic polyisocyanate composition and a
polyfunctional
isocyanate reactive composition is often expressed by a quantity known in the
art as the
Index. The Index of such a mixing activated formulation is simply the ratio of
the total
number of reactive isocyanate (-NCO) groups present to the total number of
isocyanate
reactive groups (that can react with the isocyanate under the conditions
employed in the
process). This quantity is often multiplied by 100 and expressed as a percent.
Typical
index values in the mixing activated formulations, which are suitable for use
in the
24
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invention range from about 70 to about 150%, but may extend as high as about
1500% if
an optional catalyst for the trimerization of isocyanate groups is included in
the catalyzed
reaction mixture. A preferred range of Index values is from 90 to 110%. A
still more
preferred index range is from 100 to 110%. A yet more preferred index range is
from 100
to 105%. Another preferred range of Index values is from 200 to 700%, when an
optional
catalyst for the trimerization of isocyanate groups is included in the
catalyzed reaction
mixture.
A long fiber based reinforcing material provides both mechanical strength to
the
pultruded composite and as the means for transmitting the pulling force in the
process.
l0 The fibers should be at least long enough to pass though both the
impregnation and curing
dies and attach to a source of tension. The fibrous reinforcing structure may
be made of
any fibrous material or materials that can provide long fibers, which are
capable of being
at least partially wetted by the catalyzed reaction mixture during
impregnation. The
fibrous reinforcing structure may consist of single strands, braided strands,
woven or non-
woven mat structures, combinations of these, or the like. Mats or veils made
of long
fibers may be used, in single ply or mufti-ply structures. Suitable fibrous
materials are
those known in the pultrusion art, including, but not limited to, glass
fibers, glass mats,
carbon fibers, polyester fibers, natural fibers, aramid fibers, nylon fibers,
combinations of
these, and the like. The fibrous reinforcing materials should preferably be
dry.
2o Particularly preferred reinforcing structures are those made from long
glass fibers. In
preferred embodiments, the fibers and/or fibrous reinforcing structures are
formed
continuously from one or more reels feeding into the pultrusion apparatus and
attached to
a source of pulling force at the outlet side of the curing die. The
reinforcing fibers may
optionally be pre-treated with sizing agents or adhesion promoters known in
the art.
The weight percentage of the long fiber reinforcement in the final pultruded
composite articles may vary considerably, depending on the end use application
intended
for the composite articles. Typical reinforcement loadings are from about 30
to 95% by
weight, but more typically from 40 to 90% by weight of the final composite.
Preferred
reinforcement loadings are in the range of 60 to 90% by weight, more
preferably 70 to
90% by weight of the final composite.
It is within the broader scope of the invention to use mixing activated
reaction
systems comprising more than two components. However, two component mixing
activated systems are most preferred.
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I
In the most preferred embodiments, a polyisocyanate component [A-Component]
and an isocyanate reactive component [B-Component] are the only components
that are
fed into the impregnation die of the pultrusion process. The polyisocyanate
component
contains the polyisocyanate composition and any additives that have been
premixed
therewith. The isocyanate reactive component contains the isocyanate reactive
composition and any additives that have been premixed therewith. The term
"additives"
is understood to encompass both the required catalysts and any optional
additives.
The impregnation die must provide for adequate mixing of the reactive
components and adequate impregnation of the fibrous reinforcing material. The
to impregnation die may preferably be fitted with a mixing apparatus, such as
a static mixer,
which provides for mixing of the reactive components before the resulting
catalyzed
reaction mixture is used to impregnate the fibrous reinforcing structure.
Other types of
optional mixing devices may be used. They may include, but are not limited to,
high-
pressure impingement mixing devices or low pressure dynamic mixers such as
rotating
paddles. In some cases, adequate mixing is provided in the impregnation die
itself,
without any additional mixing apparatus.
In the most preferred embodiments, the additives, including the required
catalyst
composition and any optional additional catalysts, are pre-mixed with the
isocyanate
reactive composition prior to mixing of the latter with the polyisocyanate
composition.
2o However, it is to be understood that those additives that are not
themselves polyfunctional
isocyanate reactive materials are to be considered (counted) as entities
separate from the
isocyanate reactive composition, even when mixed therewith. Likewise, if the
additives,
or any part thereof, are premixed with the polyisocyanate composition, these
are to be
considered as entities separate from the polyisocyanate composition, except in
the rare
case where they are themselves polyfunctional isocyanate species.
In an especially preferred embodiment of the process, the two component mixing-
activated chemical formulation (that is precursor to the catalyzed reaction
mixture) is
formulated to provide for mixing at a component weight ratio of about 1:1.
The pultrusion apparatus preferably contains at least one impregnation die and
at
least one curing die. The curing die operates at a higher temperature than the
impregnation die. The pultrusion apparatus may optionally contain a plurality
of curing
dies, or zones. Different curing zones may be set at different temperatures,
if desired, but
all the zones of the curing die should be higher in temperature than the
impregnation die.
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The pultrusion apparatus may optionally contain a plurality of impregnation
dies.
Preferably, there is just one impregnation die, and this preferably is
situated immediately
prior to the first curing die (or zone). The impregnation die is set at a
temperature that
provides for some degree of reaction (polymerization) between the
polyisocyanate and
the polyisocyanate-reactive ingredients in the catalyzed reaction mixture
before the
fibrous reinforcing structure, which has been at least partially impregnated
with said
reaction mixture, enters the first curing die (or zone). It is highly
preferable that the
catalyzed reaction mixture retains some degree of flowability (liquidity)
until it enters the
first curing die (or zone).
l0 It is highly preferred that the wetting of the fibrous reinforcing
structure of the
reaction system be complete and that there be no dry spots, which would lead
to surface
defects or voids in the cured composite. Further details about preferred
mixing activated
isocyanate-based pultrusion processing methods and apparatus are provided in
WO
00/29459.
In a highly preferred embodiment, the chemical precursors (used to prepare the
catalyzed reaction mixture) is substantially free of organic species, other
than carbon
dioxide, boiling less than 200°C at 1 atmosphere pressure. In a still
more highly preferred
embodiment, the catalyzed reaction mixture is substantially free of organic
species, other
than carbon dioxide, boiling less than 250°C at 1 atmosphere pressure.
In an even more
2o highly preferred embodiment, the catalyzed reaction mixture is
substantially free of
organic species, other than carbon dioxide, boiling less than 260°C at
1 atmosphere
pressure.
In yet another highly preferred embodiment, the catalyzed reaction mixture is
substantially free of organic species, other than carbon dioxide, having a
vapor pressure
greater than or equal to 0.1 mmHg at 25°C. In yet another highly
preferred embodiment,
the catalyzed reaction mixture is substantially free of any organic species
having a vapor
pressure greater than or equal to 0.1 mmHg at 25°C. By "substantially
free" it is meant
that the catalyzed reaction mixture contains less than 10% by weight of all
such organic
species combined, relative to the total weight of the catalyzed reaction
mixture (including
3o all optional additives that may be present therein). More preferably, the
catalyzed
reaction mixture contains less than 5% by weight of all such organic species
combined,
relative to the total weight of the catalyzed reaction mixture. Still more
preferably, the
catalyzed reaction mixture contains less than 2% by weight of such organic
species, even
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more preferably less than 1%, most preferably less than 0.5%, and ideally less
than 0.1%,
relative to the total weight of the catalyzed reaction mixture. The catalyzed
reaction
mixture contains less than 0.1% by weight, more preferably less than 0.01% by
weight,
and most preferably 0%, of styrene or methyl methacrylate.
Tt has surprisingly been found that a new class of mixing activated isocyanate-
based two component liquid precursors containing the required combination of
metal
based catalysts for pultrusion have resulted in substantially improved
processing.
Substantially higher line speeds, better processing efficiency, and improved
part quality
have been achieved. The catalyzed reaction mixtures used in the reaction
systems and
1o process of the invention exhibit certain gel time ranges under a dry
atmosphere.
The reaction systems are thermosetting systems, which preferably cure by
forming
a covalently crosslinked organic network polymer structure as the matrix resin
of a fiber
reinforced composite. The catalyzed reaction mixture (that is, the chemical
precursor
mixture that forms the matrix resin), which initially contains both free
alcoholic -OH
groups and free isocyanate (-NCO) groups, has a gel time of greater than 768
seconds at
25°C and a gel time of not greater than 120 seconds at 175°C. It
is to be understood that
the catalyzed reaction mixture is the (mixed) reaction system (as defined
above) without
the reinforcing fibers.
In preferred embodiments, the catalyzed reaction mixture has a gel time at
25°C of
2o greater than 900 seconds. In more preferred embodiments, the catalyzed
reaction mixture
has a gel time at 25°C of 1000 seconds or more. In still more highly
preferred
embodiments, the catalyzed reaction mixture has a gel time at 25°C in
the range of from
1000 seconds to 4000 seconds. In yet more highly preferred embodiments, the
catalyzed
reaction mixture has a gel time at 25°C in the range of from 1000
seconds to 3900
seconds, and a gel time at 175°C of less than 120 seconds.
In another preferred embodiment, the catalyzed reaction mixture has a gel time
at
25°C of greater than 1000 seconds but less than 1200~seconds, and a gel
time at 175°C of
less than 60 seconds. In yet another preferred embodiment, the catalyzed
reaction
mixture has a gel time at 25°C of from 2400 seconds to 2700 seconds,
and a gel time at ,
175°C of from 60 seconds to 120 seconds. In still another preferred
embodiment, the
catalyzed reaction mixture has a gel time at 25°C of from 3000 seconds
to 3300 seconds,
and a gel time at 175°C of from 60 seconds to 120 seconds. In still
another preferred
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embodiment, the catalyzed reaction mixture has a gel time at 25°C of
from 3600 seconds
to 3900 seconds, and a gel time at 175 °C of from 60 seconds to 120
seconds.
These gel time ranges are all determined on the complete formulation (with any
optional additives that may be present), but without the reinforcing fibers
present, under
mixing conditions similar to those employed in the actual pultrusion
apparatus. They are
measured according to the following general procedure (in the absence of the
reinforcing
fibers):
Procedure for determining reactivity parameters (at 25°C):
to ~ Add required weights of the fully formulated Isocyanate component (A-
component)
and the fully formulated Polyol component (B-component), including all
additives, to
the container used for mixing in a DAC 400 FV lab mixer. This mixer is known
as a
Speed Mixer and is manufactured by Hauschild Engineering. The use of this
particular type of mixer minimizes entrainment of air into the liquid resin
sample.
The chemical components and apparatus are initially all at 25°C. Make
sure there is
at least 1008 of material for the mixer to function properly, but not greater
than 200 g
of material. The target scale of the reaction should be 120 g of material.
Mixing
should be performed under a dry atmosphere (i.e. dry air or dry nitrogen). The
B-
component is first weighed into the mixing container, followed by the A-
component,
2o at the appropriate weight ratio of the components. The mixing container is
then
immediately closed and inserted into the mixer.
~ Mix material for 25 seconds @ 2250 rpm. Start the timer as soon as you begin
the
mixer.
~ Once mixer stops, pour material into a small (approximately 125 ml) cup to
obtain the
reactivity.
~ The material is usually thick, creamy beige in color, and turns a clear
brown as the
mixture reacts.
~ To check for the gel time, lightly touch a wood tongue depressor (or,
alternatively, a
stainless steel spatula) to the surface of the material. The material has
gelled when a
3o string is pulled from the top surface. A string resembles a fine, spun web.
Keep in
mind that touching a wood stick to the surface may cause foaming.
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~ A hard time may then be obtained. A hard time can be noted when the tongue
depressor hits a hard, or cured, spot on the surface of the material.
Procedure for determining reactivity parameters on a hot plate
(175°C):
~ As mentioned above, after the material has been poured into the 125 ml cup,
the
reactivity can be checked on a hot plate while the reaction is taking place.
The
procedure, to this point, is exactly as described above (for 25°C).
~ The reactivity should be taken at 175°C. Using a temperature probe,
find a spot on the
plate that is 175°C.
l0 ~ Use a flat steel washer and a syringe to get consistent results. The
washer should have
an external diameter of 2.25 in., and internal diameter (inner ring diameter)
of 15/16
in., and a thickness of 1/8 in. Place the center of the washer ring over the
spot that is
175°C. Leave it there for 5 min., and then check that the temperature
of the center
(hole) is 175° C. This should be sufficient time for the temperature of
the washer to
equilibrate to that of the hot plate (175°C). Have a second stop watch
ready to note
the reactivity.
~ Draw 2cc of the catalyzed reaction mixture from the cup into the syringe.
When the
timer that is being used to get the 25°C gel time shows 3 minutes,
simultaneously start
the second stop watch as the material is dispensed into the middle of the
ring. The
2o material should fill the circle right to the rim.
~ There are three times that should be noted:
1. Cream time- when the full circle of material has turned from opaque to
clear.
2. Gel time- when the material produces a fine string from the surface when
the
wooden tongue depressor is pulled away. Take the gel time from the center of
the
circle.
3. Hard time- when the material has fully cured.
The material, once cured, should pop right out of the circle so that the
washer may be
reused. Scrape off any remaining residue so that the washer will continue to
lie flat on
the hot plate.
The preferred two-component mixing activated chemical formulations disclosed
herein provide a surprising combination of long open time at relatively low
temperature
with fast cure at relatively high temperature. The catalyzed reaction mixtures
formed
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from these compositions generally cure homogeneously and do not form separated
solids
prior to entering the first curing zone of the pultrusion line. This
homogeneity of cure
(without solids separation) is highly desirable.
The catalyst compositions disclosed herein, particularly those having the
preferred ,
combination of catalytic metals, have unexpectedly provided reaction systems
that are
processable at much higher pultrusion line speeds than comparable systems of
the prior
art. The higher pultrusion processing rates are achieved without unacceptable
increases
in processing problems, such as powdering and sloughing.
The invention is further illustrated by the following non-limiting Examples.
l0 Examples
In the Examples that follow, all percentages given are percentages by weight
unless indicated otherwise. All component (AB) ratios are weight ratios unless
indicated
otherwise. The B-component composition is defined for each Example. The
isocyanate
used in each Example is the A-component.
Glossary:
1) JEFFOL~ G 30-650 polyol: Is an oxypropylated glycerol, nominal triol having
an
hydroxyl number of about 650, available from Huntsman.
2) JEFFOL~ G 30-240 polyol: Is an oxypropylated glycerol, nominal triol having
an
2o hydroxyl number of 240, available from Huntsman.
3) JEFFOL~ G 31-55 polyol: Is an oxypropylated and oxyethylated glycerol, a
nominal
flexible triol having an hydroxyl number of about 55. It is available from
Huntsman.
4) JEFFOL~ G 31-35 polyol: Is an oxypropylated and oxyethylated glycerol, a
nominal
flexible triol having an hydroxyl number of about 35. It is available from
Huntsman.
5) JEFFOL~ SD-441 polyol: Is a polyol composition obtained by oxypropylation
of a
mixture of sucrose and a glycol. This polyol has a number averaged hydroxyl
functionality of greater than 3, and an hydroxyl value of about 440. It is
available
from Huntsman.
6) SIJPR.ASEC~ 9700 polyisocyanate: Is a liquid polymeric 1VIDI product having
a free
3o isocyanate group content of about 31.5% by weight and a number averaged
isocyanate group functionality of about 2.7. This product is available from
Huntsman.
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7) RUBINATE~ 1790 polyisocyanate: Is a liquid derivative of pure 4,4'-MDI that
contains urethane groups, has a number averaged functionality of isocyanateh
groups
of about 2.00 and an isocyanate group content of about 23% by weight. This
derivative is commercially available from Huntsman.
8) Molecular Sieve 3: Alternatively BAYLITH~ 3A sieve, BAYLITH~ 4A sieve, or
any mixture thereof. Both of these molecular sieve moisture scavenger products
are
available from Bayer Corporation.
9) TECHLUBE~ BR 550 lubricant: Is a proprietary internal mold release agent
containing complex complex condensation polymer of synthetic resins, glyceride
and
to organic esters manufactured by Techniclf Products, Rahway NJ.
10) Molecular Sieve 4: Is a molecular sieve moisture scavenger product having
a pore
size of 4 Angstroms, such as BAYLITH~ 4A sieve available from Bayer
Corporation.
11) COSCAT~ BiZn catalyst: Is a proprietary organometallic catalyst
composition
believed to comprise bismuth and zinc, commercially available from Caschem
Chemical Corporation.
12) K-I~AT~ 5218 catalyst: Is an aluminum chelate catalyst believed to be
aluminum
acetlylacetonate. This catalyst product is commercially available from Ding
Industries.
13) Mold Wiz~ INT1938MCH: Is an internal mold release additive (IMR) available
from Axel Industries. It detailed composition is proprietary.
14) FOMREZ~ UL29 catalyst: Is an organotin catalyst from Witco Corp.
Pultrusion of Polyurethane and Polyisocyanurate Systems
Generally, pultrusion of polyurethane and polyisocyanurate systems with fiber
reinforced composites is performed by supplying the formulated isocyanate and
polyol
components to a mixlmetering machine for delivery in a desired ratio to a
mixing
apparatus, preferably a static mixer, to produce a reaction mixture. The
catalyzed
reaction mixture is supplied to an injection die where it can be used to
impregnate fibers
being pulled concurrently into the injection die where partial polymerization
and
impregnation of the fibrous reinforcing materials occurs. The resulting
incompletely
cured composite is pulled through a zoned heating die, attached directly to
the injection
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die, having a desired cross-section where it is shaped and fully cured. The
dynamic
forces needed to pull the composite through the forming die is supplied by the
pulling
machine. This machine typically consists of gripping devices that contact the
cured
composite profile (or the glass fibers therein) and give the traction
necessary to pull the
composite profile through the die. The machine also consists of a device that
develops a
force in the desired direction of pull that gives the impetus necessary to
pull the
composite profile continuously through the die. The resulting composite
profile upon
exiting the pulling machine is then cut to the desired length 'typically by an
abrasive cut
off saw.
to The Examples outlined below have been processed on a lab pultrusion line.
The
meter/mix machine used to supply the catalyzed reaction mixture to the
injection die was
Liquid Control Corp., North Canton, OH, Model RPV. It supplies the liquid
reaction
components at the desired ratio to a static mixer at a rate of approximately 2
g/s. The
static mixer is equipped with two static mixing tubes in series with 30
polypropylene
elements each which combines the reactants to form a homogeneous mixture. The
inside
diameter of this static mixer is 8 mm and the overall length of each unit is
32.26 cm.
The static mixer is attached to an injection box that combines the catalyzed
reaction mixture with the reinforcement that is being pulled concurrently
through the
injection box. The injection box internal dimensions are 8 in. long by 1.5 in.
wide by 0.6
2o in. tapering to 0.1 in. high. The injection box is attached to the curing
die that has internal
measurements of 26 in. long by 1.5 in. wide by 0.120 in. high. The curing die
has two ~ 12
in. long heated zones equipped with electrical heating coils individually
controlled to
maintain the desired temperatures. Curing dies with three zones may also be
used.
The reinforcement used in the preparation of the pultruded composite were in
the
form of 45 fiberglass rovings supplied by Owens Corning Fiberglass Co., 366AD
Type
30, 4400 Tex. A pulling machine manufactured by Huntsman International LLC
pulled
the rovings and composite. It is a caterpillar type machine in which the
grippers provide
the propulsion that drives the process.
Example 1 and Comparative Example A:
Evaluated in laboratory and on pultrusion line.
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The mixing activated formulation shown in Example 1 (according to the
invention) uses a
commercial organo-aluminum based catalyst (an aluminum acetylacetonate
catalyst)
obtained from King Industries, in combination with an organotin based
catalyst. The
formulation provides unexpected and surprising improvements in pultrusion -
processing,
facilitating the achievement of higher practical line speeds than prior art
formulations.
The improvements stem from the use of the mixed metal catalyst composition.
The
catalyst composition contains two different metals, aluminum and tin, in
effective
amounts.
The formulation and a description of the observed improvements resulting from
1o its use in pultrusion are provided in detail below in Example 1. The
formulation is a two
component mixing activated reactive formulation. A comparative example,
Example A,
is shown to illustrate the benefits of the invention.
The formulation shown below for Example 1 is not to be construed as limiting
on
the scope of the invention.
~ The pultrusion formulation of Example 1 consists of a polyol blend component
(below) and a polyisocyanate component (below). The ratio of the polyol blend
and
polyisocyanate components, used in Example l, is uniquely defined by its
Isocyanate
Index (which is 105%). The numbers corresponding to the amounts of the
individual
ingredients in the B-component below are expressed in parts by weight (PBW).
The filler
(CaC03), the internal mold release, and the molecular sieves are optional
additive
ingredients. However, the use of the internal mold release (IMR) and the
molecular
sieves are highly preferred.
B-Component:
JEFFOL~ G30-650 polyol 85
JEFFFOL~ G31-35 polyol 7.75
SILOSIV~ A3 molecular sieves 2.5
Mold-Wiz~ INT1938MCH mold release 5
K-KAT~ 5218 catalyst 0.75
FOMREZO UL29 catalyst 0.25
CaC03 40
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The polyisocyanate component (A-Component) is SUPRASEC~ 9700 isocyanate,
from Huntsman. The two component mixing activated system is processed at an
Isocyanate Index of 105%. This corresponds to a weight ratio of the two
components on
an unfilled basis of 1.4/1 A/B (i.e., without the calcium carbonate filler
shown). With
said filler (as shown above) the weight ratio of the components, which
satisfies the 105%
Index, 'is 1:1. '
The polyol blend, with the additives, is the B-component. The polyiso,cyanate
is
the A-component. The composition of the B-Component blend (above) is by weight
l0 (expressed as PBW). The component ratios are by weight and correspond to
the quoted
Isocyanate Index.
The following reactivity observations were made on the catalyzed reaction
system
(without the fibrous reinforcement structure):
Room Temp 250 F Hot Plate
Gel Hard Time Hard Time
21 min 22 min 52 sec
Pultrusion Run:
The system shown above, with 0.75 pbw of I~-KAT~ 5218 catalyst and 0.25 pbw
of FOMREZ~ UL29 tin catalyst, was run on a pultrusion line to produce a glass
fiber
reinforced flat profile. The following observations were made:
Die EXAMPLE 1: Line Speed whereComparative Example A: Line
Speed
Temp* powdering starts with K-KA.Twhere powdering starts with
5218 1.5 PBW
catalyst / FOMREZ UL29 catalystCOSCATO BiZn catalyst only
as shown above
250 50"/min < 24"/min
F
275 60"/min (very very slight
F powdering)
300 86"/min (very very slight 48"/min (heavier powdering)
F powdering)
'The "Die Temp" is the surface temperature of the curing die.
A step change in line speed in production of 3 mm thick flat profiles is
shown.
The purges (i.e., surfaces of the composite during line stoppages) look better
with the
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catalyst package according to the invention. The powdering that is eventually
observed
with the catalyst package according to the invention is much less than with
the BiZn
catalyst package (which is not according to the invention).
The pultruded parts made by the process of the invention cured up very well
and
no glass read-through was observed. No problems with achieving complete fiber
wetout
were seen, even at 86"/min.
The line speed of 86"/min was the maximum speed which could be achieved on
the pultrusion line used.
The use of the combination of the organoaluminum catalyst (i.e., Al-ac-ac)
with
1o the organotin catalyst is a preferred embodiment of the invention.
Comparative Example B and Examples 2 and 3:
The following is a list of formulations for pultrusion systems, and some
pultrusion
trial results. Some of these systems (Ex-2 and Ex-3, which are both according
to the
invention) showed an unexpected and surprising improvement in processability.
Specifically, it was possible to process the inventive formulations
consistently at higher
than expected line speeds in a reactive pultrusion process using long glass
fiber
reinforcement. The principle factor that limits line speed in pultrusion, for
these reactive
polyurethane formulations, is the sloughing off of partially cured resin
particles. This
2o phenomenon, known as "powdering", occurs at higher line speeds with the
inventive
formulations, relative to the others. The improvement appears to be related to
the use of a
combination of at least two different metal catalysts. The preferred
formulations shown
below contain an organotin catalyst (LTL 29) in combination with an
organobismuth
catalyst (BiZn). The best performing system additionally contained an
organoaluminum
catalyst (I~-I~AT 5218). The two inventive formulations are the last two on
the right hand
side of the Table I below. The organobismuth~ catalyst (BiZn) is believed to
contain an
organozinc compound as well as an organobismuth compund. The enhanced line
speed
performance may conceivably be due to an interaction of one organometal
catalyst with
organic species (such as ligands) from one or more of the other organometal
catalysts.
3o However, it is currently believed that at least two different metals are
required in the
catalyst composition for the best results.
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The formulations shown in Table I were run with SUPRASEC~ 9700 isocyanate
as the polyisocyanate. The glass fiber loading was about 80% by weight of the
final
pultruded part weight.
Comparative Example B (shown in the Table below) is outside the invention. The
basic details of the pultrusion process, the glossary of formulation
ingredients, and other
relevant details may be found above.
TABLE I:
Comp-B Ex-2 Ex-3
JEFFOL G30-650 polyol 85 85 85
JEFFOL G31-35 polyol 7.75 7.75 7.75
Techlube BR S50 product 0 0 0
INT 193 8 MCH 7. 5 7. 5 7. 5
Silosiv A3 sieve* 2.5 2.5 2.5
Fomrez UL 29 catalyst 0 0.1 0.1
Coscat BiZn product 1 1 1
Al-ac-ac [K-I~AT 5218 catalyst**]0 0 0.05
CaC03 20 20 20
Iso/Polyol weight ratio 1.17 1.17 1.17
Iso/Polyol weight ratio 1 1 1
Line speed where powdering started60"/min 78"/min 86"/min
* From Grace Davison Co.
* * From Ding Industries.
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