Note: Descriptions are shown in the official language in which they were submitted.
CA 02203730 1997-04-25
POLYURETHANE FOAM AND PROCESS FOR PRODUCTION THEREOF
In one of its aspects, the present invention relates to a polyurethane foam
and
to a process for production thereof. In another of its aspects, the present
invention
relates to a polyol-solids dispersion useful in the production of the
polyurethane foam
and to a process for production of the polyol-solids dispersion.
Isocyanate-based polymers are known in the art. Generally, those of skill in
the
art understand isocyanate-based polymers to be polyurethanes, polyureas,
polyisocyanurates and mixtures thereof.
It is also known in the art to produce foamed isocyanate-based polymers.
Indeed, one of the advantages of isocyanate-based polymers compared to other
polymer
systems is that polymerization and foaming can occur in situ. This results in
the ability
to mould the polymer while it is forming and expanding.
One of the conventional ways to produce a polyurethane foam is known as the
"one-shot" technique. In this technique, the isocyanate, a suitable polyol, a
catalyst,
water (which acts as a reactive "blowing" agent and can optionally be
supplemented
with one or more physical blowing agents) and other additives are mixed
together at
once using, for example, impingement mixing (e.g. high pressure). Generally,
if one
were to produce a polyurea, the polyol would be replaced with a suitable
polyamine.
A polyisocyanurate may result from cyclotrimerization of the isocyanate
component.
Urethane modified polyureas or polyisocyanurates are known in the art. In
either
scenario, the reactants would be intimately mixed very quickly using a
suitable mixing
technique.
Another technique for producing foamed isocyanate-based polymers is known
as the "prepolymer" technique. In this technique, a prepolymer is produced by
reacting
polyol and isocyanate (in the case of a polyurethane) in an inert atmosphere
to form a
liquid polymer terminated with reactive groups (e.g. isocyanates). To produce
the
foamed polymer, the prepolymer is thoroughly mixed with a lower molecular
weight
polyol (in the case of producing a polyurethane) or a polyamine (in the case
of
producing a modified polyurea) in the presence of a curing agent and other
additives,
as needed.
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CA 02203730 2001-11-07
Regardless of the technique used, it is known in the art to include a filler
material in the reaction mixture. Conventionally, filler materials have been
introduced
into foamed polymers by loading the filler material into one or both of the
liquid
isocyanate and the liquid active hydrogen-containing compound (i.e. the polyol
in the
_'i case of polyurethane, the polyamine in the case of polyurea, etc.).
The nature and relative amounts of filler materials used in the reaction
mixture
can vary, to a certain extent, depending on the desired physical properties of
the
foamed polymer product, and limitations imposed by mixing techniques, the
stability
of the system and equipment imposed limitations (e.g. due to the particle size
of the
filler material being incompatible with narrow passages, orifices and the like
of the
equipment) .
In the art of isocyanate-Laced foam polymers, particularly polyurethane foam,
it is known to use polyvinyl chloride as a filler material. See, for example,
United
States patent 5,432,204.
1:i In the past, polyvinyl chloride has been incorporated into polyurethane
foams
to confer flammability resistance to the latter. Conventionally, particulate
polyvinyl
chloride would be incorporated into the resin stream and, upon reaction of the
resin
stream with the isocyanate stream, the particulate polyvinyl chloride would be
physically dispersed throughout the polyurethane foam matrix.
Other than such a physical mixture of the two polymers, to the knowledge of
the present inventors, there has been no report of the use of partially
modified
polyvinyl chloride to enhance the "hardness" or "load building" properties of
a
polyurethane foam.
In the art of polyurethane foam there is a consistent need for the development
of novel load building technique;. In this regard, it is conventional to build
load in
polyurethane foam by the use of polymer polyols (discussed in more detail
hereinbelow) or the addition of solid filler materials. Thus, it would be
desirable to
have a load building technique which could be conveniently applied to
polyurethane
foam as an alternative to conventional load building techniques. It would be
further
desirable if the load building technique were relatively inexpensive and/or
improve
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CA 02203730 1997-04-25
other properties of the polyurethane foam (e. g. flame retardancy, anti-
fogging in
automotive applications and the like).
It is an object of the present invention to provide a novel polyurethane foam.
It is another object of the present invention to provide a novel process for
producing a polyurethane foam.
It is yet another object of the present invention to provide a novel polyol-
solids
dispersion useful, inter alia, in the production of a polyurethane foam.
It is yet another object of the present invention to provide a novel process
for
producing a polyol-solids dispersion.
Accordingly, in one of its aspects, the present invention provides a
polyurethane
foam comprising a polyurethane foam matrix having disposed therein polyvinyl
chloride in particulate form having an average particle size of less than
about 25 ~,m,
the polyvinyl chloride being at least partially modified.
In another of its aspects, the present invention provides a process for
producing
a polyurethane foam comprising reacting together:
(a) a polyol comprising a particulate solid material dispersed in a polyol,
the
particulate solid material being present in an amount in the range of from
about 1 to
about 40 percent by weight of the polyol-solids dispersion, the particulate
solid material
consisting essentially of from about 1 to 100 percent by weight of polyvinyl
chloride
and from 0 to about 99 percent by weight of a second solid, the polyvinyl
chloride
having an average particle size of less than about 25 ~.m;
(b) an isocyanate;
(c) water; and
(d) a catalyst capable of catalysing a reaction between the polyol, the
isocyanate and water.
In yet another of its aspects, the present invention provides a polyol-solids
dispersion comprising a particulate solid material dispersed in a polyol, the
particulate
solid material being present in an amount in the range of from about 1 to
about 70
percent by weight of the polyol-solids dispersion, the particulate solid
material
consisting essentially of from about 1 to 100 percent by weight of polyvinyl
chloride
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CA 02203730 1997-04-25
and from 0 to about 99 percent by weight of a second solid, the polyvinyl
chloride
having an average particle size of less than about 25 ~.m.
In yet another of its aspects, the present invention provides a process for
producing a polyol-solids dispersion comprising the steps of:
(a) adding from about 1 to about 70 parts by weight of a particulate solid
material to from about 30 to about 99 parts by weight of a polyol to provide a
mixture,
the particulate solid material consisting essentially of from about 1 to 100
percent by
weight of polyvinyl chloride and from 0 to about 99 percent by weight of a
second
solid, the polyvinyl chloride having an average particle size of less than
about 25 Vim;
(b) subjecting the mixture to an energy sufficient to render the polyvinyl
chloride in a substantially deagglomerated state;
(c) wetting the particulate solid material with the polyol; and
(d) maintaining the temperature of the mixture at less than about 50°C.
As used throughout this specification, the term "polyol-solids dispersion" is
intended to encompass a liquid dispersion comprising a liquid polyol having
dispersed
therein a solid particulate material. Further, as used throughout this
specification, the
term "partially modified polyvinyl chloride" is intended to mean polyvinyl
chloride
wherein a portion of the polymer chains have been subjected to
dehydrochlorination or
the original polymer chains contain a reactive double bond.
Dehydrochlorination is
discussed in more detail hereinbelow.
Thus, novel polyurethane foams has been discovered. Specifically, the present
polyurethane foam contains polyvinyl chloride particles. The polymer chains of
the
polyurethane are believed to be chemically inter-reactive with those of the
polyvinyl
chloride. Thus, the present polyurethane foam can be considered to be "inter-
reacted
polymer network" (IRPN). The present polyurethane foam is characterized by
improved hardness. Under certain circumstances, this property is very
important in the
manufacture of moulded, flexible polyurethane foams.
In one of its aspects the present invention relates to a polyurethane foam. As
used throughout this specification the term "polyurethane foam" is intended to
have a
broad meaning and encompasses polyurethane and urea-modified polyurethane. As
is
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CA 02203730 1997-04-25
known in the art, the term "modified" , when used in conjunction with a
polyurethane
means that up to 50 % of the polymer backbone forming linkages have been
substituted.
Thus, the present inventors have discovered that, in certain circumstances, it
is
possible improve the hardness of a polyurethane foam in a novel manner by
incorporating therein partially modified polyvinyl chloride. While not wishing
to be
bound by any theory or mode of action, it is believed that a reason for the
ability to
confer improved hardness to a polyurethane foam in accordance with the present
invention results primarily from a chemical bond between the polymer chain,
i.e. the
polymeric chains of polyurethane and those of polyvinyl chloride.
While the precise nature of the interaction between the polymer chains of
polyurethane and polyvinyl chloride are not clear, it is believed that the
interaction
proceeds in the following manner. As is known in the art, upon exposure to
heat
(temperatures greater than about 50°C), ultraviolet light or gamma
radiation, polyvinyl
chloride is susceptible to degradation (or modification) via
dehydrochlorination
pursuant to the following reaction:
~CH-CH -CH-CH~
H C1 H Cl
-2HC1
~CH=CH -CH=CH~
It is known that up to about 15 "adjacent" conjugated double bonds can be
formed in
this manner along a given portion of the polymer chain. While
dehydrochlorination of
a single monomer unit is illustrated, those of skill in the art will recognize
that
dehydrochlorination of adjacent monomer units will result in production of a
conjugated
double bond structure. Such dehydrochlorination results in partial degradation
(or
modification) of the polyvinyl chloride. As is known in the art,
dehydrochlorination
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CA 02203730 1997-04-25
of polyvinyl chloride is typically accompanied by one or more of the
following:
discolouration of the polyvinyl chloride to dark brown and rapid deterioration
of the
original mechanical and electrical properties of polyvinyl chloride
homopolymer.
While the polyvinyl chloride art has strived to deal with this problem by
stabilization
of the polymer against dehydrochlorination, it is believed that partially
modified
polyvinyl chloride can be used advantageously to confer load building to a
polyurethane
foam. In the context of the present invention, it is believed to be important
to control
this reaction such that the partially modified polyvinyl chloride species is
made
available to react with free isocyanate functions in the nascent polyurethane
system.
It is believed that this interaction occurs, via a 1,2-cycloaddition reaction,
in the
following manner:
~~~~C~~H-CH2-CH~
~s/O C1
/
R
O C=N
~~~~~CH-CH-CH2-CH~~~
I I C1
N-C=O
R
/C=N
O
wherein R can be the hydrocarbon backbone of the isocyanate group used to
produce
the polyurethane group or the backbone of a growing polyurethane chain. The
1,2-
cycloaddition product is a relatively unstable intermediate. In either case,
the result is
formation of covalent bonds between polyurethane and polyvinyl chloride during
chemical formation of the former. It is believed that the resulting 1,2-
cycloaddition
product is stabilized by carbon dioxide, the blowing agent formed in situ
during the
formation of polyurethane.
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CA 02203730 1997-04-25
Since the formation of the 1,2-cycloaddition product appears to be dependent
on the present of dehydrochlorinated polyvinyl chloride, controlled formation
of the
latter is important. In other words, if the polyvinyl chloride is permitted to
undergo
premature dehydrochlorination (i.e. prior to reaction with the reactants
forming
polyurethane), the chains of dehydrochlorinated polyvinyl chloride will likely
react
with one another thereby forming crosslinks between adjacent chains and
minimizing
or even eliminating the possibility of interaction with chains of
polyurethane.
The enhanced hardness of the present polyurethane foams is believed to be the
direct result of formation of bonds between the chains of polyurethane and
polyvinyl
chloride (i.e. the 1,2-cycloaddition product postulated hereinabove). This is
believed
to be the first discovery of a chemical bond between a nascent polyurethane
foam
matrix and partially modified polyvinyl chloride disposed in the polyurethane
foam
matrix to produce improved polyurethane foam products.
For practical purposes, it has been found that the use of a particular polyol-
solids dispersion is a preferred manner by which the present polyurethane
foams can
be produced. This dispersion contains particulate polyvinyl chloride and is
prepared
in a manner which mitigates or obviates occurrence of the dehydrochlorination
reacction of the polyvinyl chloride. This dispersion can contain polyvinyl
chloride in
a partially modified state (see Examples 5-10 hereinbelow) or in a relatively
unmodifed
state (see Examples 3-4 hereinbelow).
Thus, in one of its aspects, the present invention relates to a polyol-solids
dispersion comprising a particulate solid material dispersed in a polyol, the
particulate
solid material being present in an amount in the range of from about 1 to
about 70
percent by weight of the polyol-solids dispersion, the particulate solid
material
consisting essentially of from about 1 to 100 percent by weight of polyvinyl
chloride
and from 0 to about 99 percent by weight of a second solid, the polyvinyl
chloride
having an average particle size of less than about 25 ~,m.
The choice of polyol is not particularly restricted and is within the purview
of
a person skilled in the art. For example, the polyol may be a hydroxyl-
terminated
backbone of a member selected from the group comprising polyether, polyester,
polycarbonate, polydiene and polycaprolactone. Preferably, the polyol is
selected from
CA 02203730 2001-11-07
the group comprising hydroxyl-terminated polyhydrocarbons, hydroxyl-terminated
polyformals, fatty acid triglyceride;s, hydroxyl-terminated polyesters,
hydroxymethyl-
terminated polyesters, hydroxymethyl-terminated perfluoromethylenes,
polyalkyleneether glycols, polyalkylenearyleneether glycols and
polyalkyleneether
triols. More preferred polyols are selected from the group comprising
polyethylene
glycols, adipic acid-ethylene glycol polyester, poly(butylene glycol),
polypropylene
glycol) and hydroxyl-terminated polybutadiene - see, for example, British
patent No.
1,482,213. The most preferred polyol is a polyether polyol. Preferably, such a
polyether polyol has a molecular weight in the range of from about 200 to
about
20,000, more preferably from about 2,000 to about 10,000, most preferably from
about
2,000 to about 8,000.
The polyol-solids dispersion contains a particulate solid material in an
amount
in the range of from about 1 to about 70 percent by weight of the polyol-
solids
dispersion. Preferably, the particulate solid material is present in an amount
in the
range of from about 20 to about _50, more preferably from about 30 to about
40,
percent by weight of the polyol-solids dispersion.
The particulate solid material consists essentially of from about 1 to 100
percent
by weight of polyvinyl chloride and from 0 to about 99 percent by weight of a
second
solid.
2C1 Preferably, the polyvinyl chloride in the particulate solid material is
selected
from the group consisting of homcapolymer polyvinyl chloride, compounded
polyvinyl
chloride and mixtures thereof. if the polyvinyl chloride is compounded, it is
preferred
that it be selected from compounded polyvinyl chloride which is virgin or has
been
recycled. Of course, mixtures of such compounded polyvinyl chloride could also
be
2_'> used.
The choice of second solid (i.e. polyvinyl chloride is the first solid), if
present,
in the polyol-solids dispersion is not particularly restricted. Of course, it
will be
recognized by those of skill in the art that the second solid should not be
capable of
poisoning or otherwise adversel;~ affecting the polyurethane
condensation/foaming
30 reaction. Thus, the second solid rnay an inorganic material. A non-limiting
examples
of such a material may be selected from the group consisting of calcium
carbonate,
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CA 02203730 1997-04-25
barium sulfate, carbon, clay, talc, titanium dioxide, natural silicates,
synthetic silicates,
zeolites, mica, ceramics, aluminas, titanias and mixture thereof.
Alternatively, the
second solid may be an organic material. A non-limiting example of such a
material
may be selected from the group consisting of acrylonitrile, styrene-
acrylonitrile,
polyisocyanate polyadditon polymer, polyurea, polyurethane, polystyrene,
polypropylene, polyethylene, melamine, urea, starch, rubber, lignin and
mixtures
thereof. Of course, those of skill in the art will recognize that mixtures of
inorganic
and organic materials are possible.
If the second material is a polymer, it is possible and, it certain cases,
preferred
that the polymer be a recycled polymer.
When a second solid is used in the present polyol-solids dispersion, it is
preferred that the polyol and second solid in the present polyol-solids
dispersion be in
the form of a graft copolymer polyol. As is known in the art, graft copolymer
polyols
are polyols, preferably polyether polyols, which contain other organic
polymers. It is
known that such graft copolymer polyols are useful to confer hardness to the
resultant
polyurethane foam compared to the use of polyols which have not been modified
by
incorporating the organic polymers. Within graft copolymer polyols, there are
two
main categories which may be discussed: (i) chain-growth copolymer polyols,
and (ii)
step-growth copolymer polyols.
Chain-growth copolymer polyols generally are prepared by free radical
polymerization of monomers in a polyol carrier to produce a free radical
polymer
dispersed in the polyol carrier. Conventionally, the free radical polymer can
be based
on acrylonitrile or styrene-acrylonitrile (SAN). The solids content of the
polyol is
typically up to about 60 % , usually in the range of from about 15 % to about
40 % , by
weight of the total weight of the composition (i.e. free radical polymer and
polyol
carrier). Generally, these chain-growth copolymer polyols have a viscosity in
the range
of from about 2,000 to about 8,000 centipoise. When producing such chain-
growth
copolymer polyols, it is known to induce grafting of the polyol chains to the
free-
radical polymer.
Step-growth copolymer polyols generally are characterized as follows: (i) PHD
(Polyh_arnstoff Disperion) polyols, (ii) PIPA (_Poly _Isocyanate _Poly
Addition) polyols,
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CA 02203730 2001-11-07
and (iii) epoxy dispersion polyols. 1'HD polyols are dispersions of polyurea
particles
in conventional polyols and generally are formed by the reaction of a diamine
(e.g.
hydrazine) with a diisocyanate (e.g. toluene diisocyanate) in the presence of
apolyether
polyol. The solids content of the PHD polyols is typically up to about 50 % ,
usually
in the range of from about 15 %; to about 40 % , by weight of the total weight
of the
composition (i.e. polyurea particles and polyol carrier). Generally, PHD
polyols have
a viscosity in the range of from about 2,000 to about 6,000 centipoise. PIPA
polyols
are similar to PHD polyols but contain polyurethane particles instead of
polyurea
particles. The polyurethane particles in PIPA polyols are formed in situ by
reaction
of an isocyanate and alkanolamine (e.g. triethanolamine). The solids content
of the
PIPA polyols is typically up to about 80 % , usually in the range of from
about 15 % to
about 70% , by weight of the total freight of the composition (i.e.
polyurethane particles
and polyol carrier). Generally, F'I1'A polyols have a viscosity in the range
of from
about 4,000 to about 50,000 centipoise. See, for example, United States
patents
4,374,209 and 5,292,778. Epoxy dispersion polyols are based on dispersions of
cured
epoxy resins in conventional based polyols. The epoxy particles are
purportedly high
modulus fillers with improved hydrogen bonding characteristics.
Further information regarding useful graft copolymer polyols may be found, for
example, in Chapter 2 of "Flexible Polyurethane Foams" by Herrington and Hock
(1991) and the references cited therein. When a graft copolymer polyol is used
in the
present polyol-solids dispersion, it is convenient to substitute a portion of
the solids
normally present in the specific graft copolymer polyol with a portion by
weight of
polyvinyl chloride.
Preferably, the particulate solid material used in the present polyol-solids
dispersion consists solely of polyvinyl chloride.
The polyvinyl chloride prcaent in the present polyol-solids dispersion has an
average particle size of less than about 25 ~.m. Preferably the polyvinyl
chloride has
an average particle size in the range of from about 0.05 to about 7.0 Vim,
more
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CA 02203730 2001-11-07
preferably from about 0.05 to about 3.U ~,m, most preferably from about 0.05
to about
1.5 ~.m.
Preferably, the present polyol-solids dispersion has a viscosity at about
25°C
in the range of from about 2,500 to about 10,000 mPa~sec, more preferably from
about
2,500 to about 8,000 mPa~sec. most preferably from about 2,500 to about 6,000
mPa~sec.
As is known in the art of polyurethane foam production it is conventional to
refer to the polyol stream as the resin stream. This resin stream is
conventional mixed
and reacted with an isocyanate stream. In this regard, it is conventional to
mix into the
resin stream, prior to contact with the isocyanate stream, with other
additives (e.g.
catalyst, blowing agent, etc.) necessary to effect polymerization and foaming
of the
reaction mixture.
Thus, the present polyol-solids dispersion encompasses the presence of a
catalyst capable of catalysing the polymerization reaction. Such catalysts are
known,
and the choice and concentration thereof is within the purview of a person
skilled in the
art. See for example United Statca patents 4,296,213 and 4,518,778. Non-
limiting
examples of suitable catalysts include tertiary amines and/or organometallic
compounds. Additionally, as is known in the art, when the objective is to
produce an
isocyanurate, a Lewis acid must be used as the catalyst, either alone or in
conjunction
with other catalysts. Of course it will be understood by those skilled in the
art that a
combination of two or more catalysts may be suitably used.
The present polyol-solids dispersion also encompasses the presence of an
aqueous blowing agent for foaming; the polyurethane reaction mixture.
Preferably, the
aqueous blowing agent is water. ft is known in the art that the amount of
water used
as a blowing agent in the preparation of a foamed isocyanate-based polymer is
conventionally in the range of from about 0.5 to as high as about 40 or more
parts by
weight, preferably from about 1.0 to about 10 parts by weight, based on 100
parts by
weight of the total polyol content in the reaction mixture. Since the amount
of water
used in the production of polyurethane foam is limited, at least in part, by
the fixed
properties expected in the foamed polymer and by the tolerance of the
expanding foam
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CA 02203730 2001-11-07
towards self structure formation, it may be necessary, in certain
circumstances, to
utilize a substantially inert liquid extender when high loadings of solid
particulate
material are contemplated. Non-limiting examples of suitable liquid extenders
include
high molecular weight halogenated hydrocarbons, high molecular weight
hydrocarbons
and polyols.
The present polyol-solids dispersion also encompasses the presence of
conventional additives used in the polyurethane foam art. Non-limiting
examples of
such additives include: surfactants (e.g. organo-silicone compounds available
under
the tradename L-540 Union Carbide or DC 5043 from Air Products), cell openers
(e.g.
silicone oils), extenders (e.g. halogenated paraffins commercially available
as
CereclorTM S45), cross linkers (e.g. low molecular weight reactive hydrogen-
containing
compositions), pigments/dyes, dame retardants (e.g. halogenated organo-
phosphoric
acid compounds)., inhibitors (e.g. weak acids), nucleating agents (e.g. diazo
compounds), anti--oxidants, and plasticizers/stabilizers (e.g. sulphonated
aromatic
compounds).
The present polyol-solids dispersion may be produced by a process for
producing a polyol-solids dispersion comprising the steps of:
(a) adding from about 1 to about 70 parts by weight of a particulate solid
material to from about 30 to about 99 parts by weight of a polyol to provide a
mixture,
the particulate solid material consisting essentially of from about 1 to 100
percent by
weight of polyvinyl chloride and from 0 to about 99 percent by weight of a
second
solid, the polyvinyl chloride having an average particle size of less than
about 25 ~,m;
(b) subjecting the mixture to an energy sufficient to render the polyvinyl
chloride in a substantially deagglomerated state;
(c) wetting the particulate solid material with the polyol; and
(d) maintaining the temperature of the mixture at less than about 50°C.
Step (a) comprises adding a solid particulate material to a polyol. The solid
particulate material and the polyol are as described hereinabove with
reference to the
present polyol-solids dispersion. The discussion of the preferred embodiments
referred
hereinabove with respect to the particulate material and the polyol applies
equally to
the process for production of the polyol-solids dispersion.
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CA 02203730 1997-04-25
Steps (b), (c) and (d) are preferably conducted contemporaneously. The general
object is to supply sufficient energy to the mixture of solid particulate
material and
polyol to substantially wet the solid particulate material while rendering it
in a
deagglomerated state. As used throughout this specification, the term
"deagglomerated" when used in respect of polyvinyl chloride means that the
polymer
particles are disposed in a polyol in such a manner as to substantially avoid
physical
agglomeration of a series of particles such that the behave as a large
particle. As used
throughout this specification, the terms "wetting out", "wet" and "wetted", in
the
context of the present polyol-solids dispersion, are intended to mean that the
surface
of each particle of the solid particulate material is covered with the polyol
carrier.
Preferably, each particle of the solid particulate material is substantially,
more
preferably substantially completely, covered by the polyol.
The energy applied to the mixture in Step (b) is regulated to ensure that the
polyvinyl chloride is rendered in a substantially deagglomerated state. This
encompasses processing agglomerated polyvinyl chloride particles or
maintaining
deagglomerated polyvinyl chloride particles as such. Further, the temperature
of the
mixture is maintained at less than about 50°C. It is believed that a
principal reason for
this is that increased temperature would result in dehydrochlorination of the
polyvinyl
chloride subsequently resulting in an increased likelihood that polyvinyl
chloride chains
will crosslink. Maintaining the temperature of the mixture at less than about
50°C
during processing of the mixture mitigates or even eliminates the occurrence
of this
negative effect. Preferably, the temperature of the mixture is maintained at
less than
about 45°C, more preferably less than about 40°C.
In most practical embodiments, Step (c) involves cooling the vessel in which
the
polyol-solids dispersion is being produced. The nature of the vessel is not
particularly
restricted and is within the purview of a person skill in the art. Preferably,
the
equipment used for mixing and cooling of the mixture is a high shear in-line
mixer
equipped with a single stage general purpose disintegration head (e.g. a Type
LS275
mixer from Silverson Machine Incorporated). Such cooling can be achieved by
any
suitable means; this is within the purview of a person skilled in the art.
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CA 02203730 1997-04-25
The present polyol-solids dispersion is useful in the production of a
polyurethane foam. Preferably, the process for production of a polyurethane
foam
comprises reacting together:
(a) a polyol comprising a particulate solid material dispersed in a polyol,
the
particulate solid material being present in an amount in the range of from
about 1 to
about 40 percent by weight of the polyol-solids dispersion, the particulate
solid material
consisting essentially of from about 1 to 100 percent by weight of polyvinyl
chloride
and from 0 to about 99 percent by weight of a second solid, the polyvinyl
chloride
having an average particle size of less than about 25 pm;
(b) an isocyanate;
(c) water; and
(d) a catalyst capable of catalysing a reaction between the polyol, the
isocyanate and water.
Component (a) is a polyol which may comprise the polyol-solids dispersion
discussed hereinabove and, for example, a base polyol to dilute the polyol-
solids
dispersion. The discussion hereinabove of the polyol-solids dispersion,
aqueous
blowing agent and catalyst, and their respective preferred embodiments,
applies equally
in respect of the process for producing a polyurethane foam.
The isocyanate suitable for the process for producing a polyurethane foam is
not
particularly restricted and the choice thereof is within the purview of a
person skilled
in the art. Generally, the isocyanate compound suitable for use may be
represented by
the general formula:
Q(NCO);
wherein i is an integer of two or more and Q is an organic radical having the
valence
of i. Q may be a substituted or unsubstituted hydrocarbon group (e.g. an
alkylene or
arylene group). Moreover, Q may be represented by the general formula:
Q~-Z_Q~
wherein Ql is an alkylene or arylene group and Z is chosen from the group
comprising
-O-, -O-Ql-, -CO-, -S-, -S-Ql-S- and -SOz . Examples of isocyanate compounds
which
fall within the scope of this definition include hexamethylene diisocyanate,
1,8-
diisocyanato-p-methane, xylyl diisocyanate, (OCNCHZCHZCHZOCH20)2, 1-methyl-2,4-
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CA 02203730 2001-11-07
diisocyanatocyclohexane, phenylene diisocyanates, tolylene diisocyanates,
chlorophenylene diisocyanates, diphenylmethane-4,4'-diisocyanate, naphthalene-
1,5-
diisocyanate, triphenylmethane-4.4',4"-triisocyanate and isopropylbenzene-
alpha-4-
diisocyanate.
In another embodiment, Q may also represent a polyurethane radical having a
valence of i. In this case Q(NCO); is a compound which is commonly referred to
in the
art as a prepolymer. Generally, a prepolymer may be prepared by reacting a
stoichiometric excess of an isocyanate compound (as defined hereinabove) with
an
active hydrogen-containing cc:m~pound (as defined hereinafter), preferably the
polyhydroxyl-containing materials or polyols described below. In this
embodiment,
the polyisocyanate may be, for example, used in proportions of from about 30
percent
to about 200 percent stoichiometr!ic excess with respect to the proportion of
hydroxyl
in the polyol. Since the process of the present invention relates to the
production of
polyurea foams, it will be appreciated that in this embodiment, the prepolymer
would
be used to prepare a polyurethane modified polyurea (i.e. not an unmodified
polyurethane) foam.
In another embodiment, thc~ isocyanate compound suitable for use in the
process
of the present invention may be s~.tected from diners and trimers of
isocyanates and
diisocyanates, and from polymeric diisocyanates having the general formula:
LQ~~(NCO)~l;
wherein both i and j are integers having a value of 2 or more, and Q" is a
polyfunctional organic radical, and/or, as additional components in the
reaction
mixture, compounds having the general formula:
L(NCO);
2_'~ wherein i is an integer having a value of 1 or more and L is a
monofunctional or
polyfunctional atom or radical. Examples of isocyanate compounds which fall
with the
scope of this definition include ethylphosphonic diisocyanate,
phenylphosphonic
diisocyanate, compounds which contain a =Si-NCO group, isocyanate compounds
derived from sulphonamides (QSO,NC'.O), cyanic acid and thiocyanic acid.
3C1 See also for example, British patent No. 1,453,258.
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CA 02203730 1997-04-25
Non-limiting examples of suitable isocyanates include: 1,6-hexamethylene
diisocyanate, 1,4-butylene diisocyanate, furfurylidene diisocyanate, 2,4-
toluene
diisocyanate, 2,6-toluene diisocyanate, 2,4'-diphenylmethane diisocyanate,
4,4'-
diphenylmethane diisocyanate, 4,4'-diphenylpropane diisocyanate, 4,4'-diphenyl-
3,3'-
dimethyl methane diisocyanate, 1,5-naphthalene diisocyanate, 1-methyl-2,4-
diisocyanate-5-chlorobenzene, 2,4-diisocyanato-s-triazine, 1-methyl-2,4-
diisocyanato
cyclohexane, p-phenylene diisocyanate, m-phenylene diisocyanate, 1,4-
naphthalene
diisocyanate, dianisidine diisocyanate, bitoluene diisocyanate, 1,4-xylylene
diisocyanate, 1,3-xylylene diisocyanate, bis-(4-isocyanatophenyl)methane, bis-
(3-
methyl-4-isocyanatophenyl)methane, polymethylene polyphenyl polyisocyanates
and
mixtures thereof. A more preferred isocyanate is selected from the group
comprising
2,4-toluene diisocyanate, 2,6-toluene diisocyanate and mixtures thereof.
Another more
preferred isocyanate is selected from the group comprising 2,4'-
diphenylmethane
diisocyanate, 4,4'-diphenylmethane diisocyanate and mixtures thereof. The most
preferred isocyanate is a mixture comprising from about 75 to about 85 percent
by
weight 2,4-toluene diisocyanate and from about 15 to about 25 percent by
weight 2,6-
toluene diisocyanate.
In a preferred embodiment of the process to produce the polyurethane foam, the
isocyanate is used in an amount sufficient to provide an isocyanate index of
at least
about 1.00, preferably at least about 1.05, more preferably at least about
1.10, even
more preferably at least about 1.15, most preferably at least about 1.20.
Conventionally, a higher isocyanate index leads to an unstable foam matrix. It
has been
discovered that, when modified polyvinyl chloride is incorporated in the foam
matrix
as discussed hereinabove, a stable foam can be produced having load building
properties beyond those achievable using a lower isocyanate index and
conventional
load building techniques (e.g. polymer polyols, etc.).
The manner by which the polyol-solids dispersion, isocyanate, catalyst and
blowing agent are contacted is not particularly restricted and is within the
purview of
a person skill in the art. Thus, in one embodiment, it is possible to preblend
the
polyol-solids dispersion, catalyst and blowing agent to produce a resin stream
which
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CA 02203730 2001-11-07
is contact with an isocyanate stream in a conventional high pressure,
impingement
mixhead. See, for example one or more of the following:
United States patent 4,379,122 (Taubenmann);
United States patent 4,464,056 (Schmitz et al.);
United States patent 4,497,579 (Schmitz et al.);
United States patent 4,5()3,014 (Bauer);
United States patent 4,510,120 (Bauer);
United States patent 4,565,511 (Ramisch);
United States patent 4,643,581 (Soechtig et al.);
United States patent 4,721,391 (Bauer);
United States patent 4,774,059 (Wagner);
United States patent 4,854,713 (Soechtig );
United States patent 4,898,714 (Urban et al.);
United States patent 5,063,027 (Schneider);
United States patent 5,157,()59 (Bauer et al.);
United States patent 5,201,580 (Bauer);
United States patent 5,277,567 (Bauer et al.); and
United States patent 5,259,749 (Meixner et al.),
Alternatively, the resin stream rnay be contacted with the isocyanate stream
in a
conventional low pressure, mechanical mixhead. As is known in the art, a low
pressure, mechanical mixhead includes a mixer which imparts high-shear energy
between the mixing element (e.g. impeller, etc.) and the surrounding barrel.
The
mixer speed is conventionally in the range of from about 2,000 to about 13,000
rpm.
After the components for producing the polyurethane foam have been contacted,
the polymerization reaction begins. rrhis results in the occurrence of: (i) in
situ
formation of carbon dioxide which acts as a blowing agent and initiates
expansion of
the reacting, polymerizing mass, a:nd (ii) an increase in the temperature of
the reaction
3C~ mass as a result of the exothermic reactions. The increase in temperature
is believed
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CA 02203730 1997-04-25
to promote dehydrochlorination of the polyvinyl chloride present in the
reacting mass
thereby allowing the dehydrochlorinated polyvinyl chloride to inter-react with
free
isocyanate functions (i.e. -NCO) present in the form of unreacted isocyanate
and/or on
growing polyurethane chains.
As is known in the art of polyurethane foam, the ability to produce moulded,
flexible polyurethane foam is desirable since such moulded foam is the
standard in
transportation seating and trim parts, as well as in some upholstered
furniture, bedding,
packaging and novelty items. Generally, moulded foam is complicated to produce
since
at least the following factors must be accounted for in moulded foam: higher
reactivity
formulation, pour-pattern limitations, the discrete size of each individual
shot, the need
to open and close a mould lid mechanically, the choice of mould release agent,
mould
temperature latitudes and the available curing cycles. A key advantage of the
present
polyol dispersion is that it may be readily utilized in to produce moulded,
flexible
polyurethane foam. Another key advantage of the present polyol dispersion is
that it
may be used to produce such a foam having improved load bearing properties
(e.g.
hardness, indentation force deflection, etc.). Yet another key advantage of
the present
polyol dispersion is that it may be used to produce such a foam having
improved flame
retardancy.
Another surprising and unexpected advantage of the present polyurethane foam
is that it appears to have anti-fogging properties. As is known in the art,
fogging of
windshield interiors of vehicles is a problem. Recent investigations have
identified the
following materials used in polyurethane foam production as being at least
partly
responsible: antioxidants, siloxanes and amine catalysts. The volatility of
and
subsequent migration from the foam of these materials is of particular
concern. While
the problems with antioxidants and siloxanes have been mitigated by using
reduced
amounts thereof in the reactions and/or using non-volatile alternatives, the
amine
(particularly tertiary amine) catalysts continue to present a problem.
If the theory proffered above is correct concerning dehydrochlorination of the
polyvinyl chloride as being important in the interaction between the chains of
polyvinyl
chloride and polyurethane, it is believed that a very important advantage of
the present
polyurethane foam will be reduced possibility or even elimination of fogging.
As is
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CA 02203730 2001-11-07
known in the art, fogging of automobile windshields is believed to result from
reaction
of minute amounts of hydrochloric. acid evolved from polyvinyl chloride used
in the
automobile with volatile amine evolved from the foam to produce the
corresponding
solid, amine salts. These salts form on a cold, condensing surface such as the
windshield and remain adhered to this surface. 'Thus, it is believed that the
present
polyurethane foam has the potential to present a filtering effect with respect
to volatile
amine present in the foam thereby mitigating or obviating fogging of the
interior of
windshields once installed in a vehicle.
Another potential advantage of the present polyurethane foam is that it may
mitigate or obviate amine-induced staining of vinyl surface in an automobile.
As is
known in the art, "vinyl staining" occurs, for example, when a white vinyl
seat cover
comes into contact with volatile amine evolved from the foam. This is believed
to
results in staining of the white (or light-coloured) vinyl seat cover. As
described in the
previous paragraph, it is believed that the polyurethane foam of the present
invention
may act as a filter with respect to volatile amine present in the foam.
Embodiments of the present invention will now be described with reference to
the following Examples which should not be construed as limiting the scope of
the
invention. The term "pbw" used in the Examples refers to parts by weight.
In the Examples the following compounds were used:
1. ARCOL E-700, a polyol (triol) commercially available from Arco
Corporation;
2. ARCOL E-788, a polymer polyol containing approximately 38 % SAN
solids and commercially available from Arco Corporation;
3. ARCOL I~-814, a polyether polyol (molecular weight of about 6,000)
2~~ commercially available from Arco <:orporation;
4. DEOA-LFTM, diethanolamine (crosslinker);
5. DABCO-33LV, an amine polymerization catalyst commercially available
from Air Products and C'.hemicals Inc.;
6. ZF-22, a diaminc~ethyl ether catalyst commercially available from
Huntsman Corporation;
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CA 02203730 1997-04-25
7. DC5043, a silicone surfactant commercially available from Air Products
and Chemicals Inc. ;
8. DC5169, a silicone surfactant commercially available from Air Products
and Chemicals Inc. ;
9. OXY 625, polyvinyl chloride homopolymer having an average particle
size of 1.2 ~,m commercially available from Occidental Chemicals; and
10. Isocyanate, a commercially available TDI.
EXAMPLES 1-4
In these Examples, various foams were made pursuant to the formulations
provided in Table 1. As will be apparent to those of skill in the art, the
amount of
isocyanate used in Examples 1 and 3 corresponds to an isocyanate index of 1.10
whereas the amount of isocyanate used in Examples 2 and 4 corresponds to an
isocyanate index of 1.20. Further, Examples 1 and 2 contained no polyvinyl
chloride
and thus are provide for comparative purposes only.
Table 1
Ingredient Example 1 Example Example Example
2 3 4
ARCOL E-700 25.00 25.00 41.32 41.32
ARCOL E-788 75.00 75.00 48.68 48.68
H20 4.07 4.07 4.07 4.07
DEOA LF 1.41 1.41 1.45 1.45
DABCO-33LU 0.39 0.39 0.30 0.30
ZF-22 0.08 0.08 0.08 0.08
DC-5043 0.45 0.45 0.45 0.45
DC-5169 0.20 0.20 0.20 0.20
OXY 625 0.00 0.00 10.00 10.00
Isocyanate 53.57 58.44 53.57 58.44
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CA 02203730 1997-04-25
Foam samples were produced by preblend all ingredients except the isocyanate.
The polyvinyl chloride (OXY 625) was mixed into the preblend without the use
of a
high shear mixer and the temperature of the preblend was maintained below
50°C. The
preblend was mixed with the isocyanate and the resulting reaction mixture was
poured
into an aluminum mould heated to 65 ~ 2°C. Demould time was about 5
minutes for
Examples 1 and 3, and about 10 minutes for Examples 2 and 4.
The resulting foam samples were crushed in a roller crusher immediately after
demoulding and aged for about 72 hours. The aged foam samples were subjected
Indentation Force Deflection (IFD) testing pursuant to ASTM D-3574-95 (Test
B1).
The results of IFD testing are provided in Table 2. The values reported in
Table 2 are
an average of testing of two samples for each Example. The results in Table 2
demonstrate that improved load bearing properties are conferred to the
resulting
polyurethane foam when a portion (approximately one third) of the SAN in one
of the
based polymer polyols in the formulation is replaced with polyvinyl chloride
which is
incorporated into the resin preblend at a temperature which does not promote
dehydrochlorination.
Table 2
Example Example Example Example
1 2 3 4
25 % IFD (N) 261 289 285 340
50 % IFD (N) 509 560 527 632
65 % IFD (N) 824 899 816 969
25 % Return 165 182 180 209
(N)
EXAMPLES 5-10
These Examples illustrate the effect of loading bearing properties of the
final
foam product when temperature is not controlled during production of the
polyol
dispersion. The formulation of the master resin preblend used in these
Examples is
provided in Table 3.
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CA 02203730 1997-04-25
Table 3
Ingredient Amount
ARCOL E-700 25.00
ARCOL E-788 48.68
PVC Dispersion 26.32
H20 4.07
DEOA-LF 1.45
DABCO-33LV 0.39
ZF-22 0.08
DC-5043 0.45
DC-5169 0.20
The PVC dispersion was prepared using ARCOL E-700 with OXY 625. As will be
apparent to those of skill in the art, in the formulation in Table 3, a
portion of ARCOL
E-788 is replaced with the PVC dispersion to provide partial replacement of a
portion
of the solids (i.e. SAN) in ARCOL E-788 with polyvinyl chloride.
Various PVC dispersions were produced with a SHAR high shear mixer
equipped with a stainless steal container and a 3 inch impeller. The polyol
and the
polyvinyl chloride were initially preblended for 5 minutes at an impeller
mixing speed
of about 2000 rpm. There after the impeller mixing speed was increased to
about 5500
rpm to provide high shear mixing of the polyol and the polyvinyl chloride for
various
periods of time. The particulars of the preparation of each dispersion are
provided in
Table 4, together with the final temperature of each dispersion and its
viscosity at
25°C.
Each PVC dispersion was blended into the master resin preblend provided in
Table 3 above. The master resin preblend was then mixed with isocyanate in an
amount sufficient to provide an isocyanate index of 1.10 to produce a foam
same using
the same procedure described above for Examples 1-4.
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CA 02203730 1997-04-25
Table 4
Example
5 6 7 8 9 10
Polyol E-700 E-700 E-700 E-814 E-814 E-814
Mixing time 10 20 30 10 20 30
(min. )
Temperature 65 90 111 74 104 135
(C)
Viscosity (cps)5950 6150 7750 8640 10500 16750
25 % IFD (N) 270 279 296 256 243 248
50% IFD (N) 515 532 556 507 472 484
65 % IFD (N) 796 823 852 820 776 780
25 % Return 167 173 184 154 151 157
(N)
The resulting foam samples were subjected IFD testing pursuant as discussed
above for Examples 1-4. The results are provided in Table 4. For comparison a
control foam was produced using a formulation similar to that used in Example
1 (i.e.
no polyvinyl chloride). The IFD results for this foam were as follows:
% IFD: 252 N
50% IFD: 504 N
20 65 % IFD: 819 N
25 % Return: 156 N
As will be apparent to those of skill in the art, these Examples demonstrate
that partial
modification of the polyvinyl chloride can be initiated prior to the foaming
reaction to
25 produce foams which have similar or enhanced load properties compared to a
foam
containing no polyvinyl chloride. Further, when temperature control of the
dehydrochlorination (or chemical stabilization of the polyvinyl chloride) is
achieved,
the properties of the end foam product are more predictable and other changes
in the
properties (e.g. colour) are mitigated.
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