Note: Descriptions are shown in the official language in which they were submitted.
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FORMULATION METHOD FOR PLURAL COMPONENT LATEX FOAM
TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY OF THE INVENTION
The present invention relates generally to foams and, more particularly, to
two-part
spray foams formed from foamable composition that has an A-side containing a
latex and
a B-side that contains a polyfunctional aziridine crosslinking agent and a
plasticizer. The
foams are used to fill cavities, cracks, and crevasses to enhance the sealing
and insulating
properties of buildings, cars, and appliances and to form backing for carpets,
cushions,
mattresses, pillows, and toys. A method of making such foams is also provided.
BACKGROUND OF THE INVENTION
Spray foams have found widespread utility in the fields of insulation and
structural
reinforcement. For example, spray foams are commonly used to insulate or
impart
structural strength to items such as automobiles, hot tubs, refrigerators,
boats, and building
structures. In addition, spray foams are used in applications such as
cushioning for
furniture and bedding, padding for underlying carpets, acoustic materials,
textile
laminates, and energy absorbing materials. Currently, spray foams, especially
those used
as insulators or sealants for home walls, are polyurethane spray foams.
Polyurethane spray foams and their methods of manufacture are well known.
Typically, polyurethane spray foams are formed from two separate components,
commonly referred to as an "A" side and a "B" side, that react when they come
into
contact with each other. The first component, or the "A" side, contains an
isocyanate such
as a di- or poly- isocyanate that has a high percent of NCO (nitrogen, carbon,
and oxygen)
functional groups on the molecule. The second component, or "B" side, contains
nucleophilic reagents such as polyols that include two or more hydroxyl
groups, silicone-
based surfactants, blowing agents, catalysts, and/or other auxiliary agents.
The
nucleophilic reagents are generally polyols, primary and secondary polyamines,
and/or
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water. Preferably, mixtures of diols and triols are used to achieve the
desired foaming
properties. The overall polyol hydroxyl number is designed to achieve a 1:1
ratio of first
component to second component (A:B).
The two components are typically delivered through separate lines into a spray
gun
such as an impingement-type spray gun. The first and second components are
pumped
through small orifices at high pressure to form separate streams of the
individual
components. The streams of the first and second components intersect and mix
with each
other within the gun and begin to react. The heat of the reaction causes the
temperature of
the reactants in the first and second components to increase. This rise in
temperature
causes the blowing agent located in the second component (the "B" side) to
vaporize and
form a foam mixture. As the mixture leaves the gun, the mixture contacts a
surface, sticks
to it, and continues to react until the isocyanate groups have completely
reacted. The
resulting resistance to heat transfer, or R-value, may be from 3.5 to 8 per
inch.
There are several problems associated with conventional polyurethane spray
foams. For example, although sealing a building with such polyurethane spray
foams
reduces drafts and keeps conditioned air inside and external air outside of a
building, there
is a reduction in the ability of moisture to penetrate the building. As a
result, the levels of
moisture and air pollutants rise in these tightly sealed buildings that no
longer permit
moisture penetration into the building.
Another problem associated with conventional polyurethane spray foams is that
the
first component (the "A" side) contains high levels of methylene-diphenyl-di-
isocyanate
(MDI) monomers. When the foam reactants are sprayed, the MDI monomers form
droplets that may be inhaled by workers installing the foam if stringent
safety precautions
are not followed. Even a brief exposure to isocyanate monomers may cause
difficulty in
breathing, skin irritation, blistering and/or irritation to the nose, throat,
and lungs.
Extended exposure of these monomers can lead to a sensitization of the
airways, which
may result in an asthmatic-like reaction and possibly death.
An additional problem with such conventional polyurethane spray foams is that
residual polymeric methylene-diphenyl-di-isocyanate (PMDI) that is not used is
considered to be a hazardous waste. PMDI typically has an NCO of about 20%. In
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addition, PMDI can remain in a liquid state in the environment for years.
Therefore,
specific procedures must be followed to ensure that the PMDI waste product is
properly
and safely disposed of in a licensed land fill. Such precautions are both
costly and time
consuming.
Attempts have been made to reduce or eliminate the presence of isocyanate
and/or
isocyanate emission by spray foams into the atmosphere. Non-limiting examples
of such
attempts are set forth below.
U.S. Patent Publication No. 2006/0047010 to O'Leary teaches a spray
polyurethane foam that is formed by reacting an isocyanate prepolymer
composition with
an isocyanate reactive composition that is encapsulated in a long-chain, inert
polymer
composition. The isocyanate prepolymer composition contains less than about 1
wt% free
isocyanate monomers, a blowing agent, and a surfactant. The isocyanate
reactive
composition contains a polyol or a mixture of polyols that will react with the
isocyanate
groups and a catalyst. During application, the spray gun heats the polymer
matrix, which
releases the polyols and catalyst from the encapsulating material. The polyols
subsequently react with the isocyanate prepolymer to form a polyurethane foam.
U.S. Patent No. 7,053,131 to Ko, et al. discloses absorbent articles that
include
super critical fluid treated foams. In particular, super critical carbon
dioxide is used to
generate foams that assertedly have improved physical and interfacial
properties.
U.S. Patent No. 6,753,355 to Stollmaier, etal. discloses a composition for
preparing a latex foam that includes a latex and a polynitrilic oxide (for
example, 2,4,6-
triethylbenzene-1,3-dinitrile oxide) or a latex and an epoxy silane. The latex
may be
carboxylated. It is asserted that the composition is stable for at least
twelve months and
that the one-part coating systems can be cured at room temperature without the
release of
by-products.
U.S. Patent No. 6,414,044 to Taylor teaches foamed caulk and sealant
compositions that include a latex emulsion and a liquid gaseous propellant
component.
The foamed compositions do not contain a gaseous coagulating component.
U.S. Patent No. 6,071,580 to Bland, et al. discloses an absorbent, extruded
thermoplastic foam made with blowing agents that include carbon dioxide. The
foam is
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allegedly capable of absorbing liquid at about 50 percent or more of its
theoretical volume
capacity.
U.S. Patent No. 5,741,823 to Hsu teaches producing a smooth, hard coating on a
wood substrate. The coating is made of a foamed, polymerized latex emulsion
and is
applied on the surface of a wood substrate.
U.S. Patent No. 5,585,412 to Natoli, et al. discloses a process for preparing
flexible
CFC-free polyurethane foams that uses an encapsulated blowing agent. The
process
provides a polyurethane foam having a desired density that avoids the use of
chlorofluorocarbons or other volatile organic blowing agents. The encapsulated
blowing
agent assertedly supplements the primary blowing action provided by water in
the
manufacture of water-blown polyurethane foam and facilitates in the production
of foam
having the desired density.
U.S. Patent No. 4,306,548 to Cogliano discloses lightweight foamed porous
casts.
To manufacture the casts, expanded non-porous polystyrene foam beads or other
shapes
are coated with a layer of neoprene, natural rubber, or other latex. The
coated polystyrene
is then encased in a porous envelope, and the envelope is applied to a broken
limb.
Additional coated polystyrene is added over the envelope and a gaseous
coagulant is
added to gel the latex, which causes the polystyrene beads to adhere to each
other and
produce a unified, rigid structure.
Latex foams have also been used to reduce or eliminate the presence of
isocyanate
and/or isocyanate emission by spray foams. Typical plural component latexes
are supplied
with a latex as the major component in the "A" side and a crosslinking agent
as the minor
component in the "B" side. The crosslinking agent in the latex spray foams is
generally
highly reactive. Thus, the crosslinking agent is generally supplied neat (that
is, not in
solution). Additionally, the high reactivity of the crosslinking agent may
reduce the
stability and result in a short shelf life of the foamable material.
Despite these attempts to reduce or eliminate the use of isocyanate in spray
foams
and/or reduce isocyanate emission into the air, there remains a need in the
art for a spray
foam that is non-toxic, environmentally friendly, and stable over time.
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SUMMARY OF THE INVENTION
In one aspect, the present disclosure provides a two-part foamable composition
for
forming a foam that includes (1) a first component including at least one
functionalized resin
selected from a functionalized water-dispersible resin and a functionalized
water-soluble resin,
and an acid and (2) a second component including a polyfunctional aziridine
crosslinking agent
that crosslinks at or about room temperature, a plasticizer that is a benzoate
ester having no
acidic protons to react with the polyfunctional aziridine crosslinking agent,
and a base. The
amount of ethyleneimine present in the second component is less than 0.03 ug/g
of the second
component. The second component may further include a non-functionalized resin
that is non-
reactive with the polyfunctional aziridine crosslinking agent. The presence of
the plasticizer
permits for the inclusion of coacervating agents, fillers, nucleating agents
and/or foaming agents
in the second component. In addition, the plasticizer reduces the viscosity of
the second
component such that the second component can be mixed with the first component
to form an
homogenous mixture. In exemplary embodiments, the functionalized resin is one
or more
members selected from a functionalized latex and an acrylic solution.
In another aspect, the present disclosure provides a foamed product comprising
the
reaction product of (1) a first component including at least one
functionalized resin selected from
a functionalized water-dispersible resin and a functionalized water-soluble
resin, and an acid and
(2) a second component including a polyfunctional aziridine crosslinking agent
that crosslinks at
or about room temperature, a plasticizer that is a benzoate ester, and a base.
The amount of
ethyleneimine present in the second component is less than 0.03 ug/g of the
second component.
The second component may further include a non-functionalized resin that is
non-reactive with
the polyfunctional aziridine crosslinking agent. In addition, at least one of
the first component
and second component further includes an alcohol co-solvent. In exemplary
embodiments, the
functionalized resin is one or more members selected from a functionalized
latex and an acrylic
solution. The plasticizer has no acidic protons to react with said
polyfunctional aziridine
crosslinking agent. The presence of the plasticizer permits for the inclusion
of coacervating
agents, fillers, nucleating agents and/or foaming agents in the second
component.
In another aspect, the present disclosure provides a method of forming a foam
barrier that
includes (1) delivering a first component including one or more functionalized
resins selected
from a functionalized water-dispersible resin and a functionalized water-
soluble resin, and an
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acid through a first delivery line to an application device, (2) delivering a
second component
including a polyfunctional aziridine crosslinking agent that crosslinks at or
about room
temperature, a plasticizer, and a base, to the application device, where the
plasticizer is a
benzoate ester, (3) mixing the first and second components within the
application device to form
a reaction mixture, (4) permitting the polyfunctional aziridine crosslinking
agent, the acid, and
the one or more functionalized resins to chemically react while the acid and
the base react to
form a gas to initiate a foaming reaction and form a foam, and (5) spraying
the foam to a desired
location. The amount of ethyleneimine present in the second component is less
than 0.03 g/g
of the second component. The desired location may be selected from an open
cavity, a closed
cavity, a crevasse and a crack. The method may also include a diluting step
where ethyleneimine
contained within the polyfunctional aziridine crosslinking agent reacts with
acid impurities and
water in the second component to reduce the level of the ethyleneimine in the
second component
to less than about 0.03 tg/g. The second component may further include a non-
functionalized
resin that is non-reactive with the polyfunctional aziridine crosslinking
agent. In addition, at least
one of the first component and second component further includes an alcohol co-
solvent.
Additionally, the presence of the plasticizer permits for the inclusion of
coacervating agents,
fillers, nucleating agents and/or foaming agents in the second component.
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It is an advantage of the present invention that the inventive foams do not
contain
the harmful chemicals found in conventional polyurethane spray foams, such as,
for
example, MDI monomers. As a result, the foams of the present invention do not
contain
harmful vapors that may cause skin or lung sensitization or generate toxic
waste.
It is also an advantage of the present invention that the spray foams do not
emit
harmful vapors into the air when the foam is sprayed, such as when filling
cavities to seal
and/or insulate a building. The inventive foams are safe for workers to
install and,
therefore, can be used both in the house renovation market and in occupied
houses.
It is another advantage of the present invention that the foams may be applied
using existing spray equipment designed for conventional two-part spray
polyurethane
foam systems without clogging the spray equipment. Thus, the application gun
is capable
of repeated use without clogging and the resulting necessary cleaning when the
foams of
the present invention are utilized.
It is yet another advantage of the present invention that diluting the
polyfunctional
aziridine crosslinking agent with a plasticizer permits the toxic components
within the
polyfunctional aziridine to be diluted and/or reacted, thereby reducing health
risks to those
individuals in contact with the foamable composition.
It is also an advantage of the present invention that the components of the B-
side of
the foam compositions may be stored for extended periods of time without
significant
reaction until the composition is used when the polyfunctional aziridine
crosslinking agent
is diluted and the B-side components do not contain any acidic protons.
It is yet another advantage of the present invention that the polyfunctional
aziridine
crosslinking agent reacts with the acid in the A-side to create a polymeric
structure of
skeleton that supports the foam while the latex is coagulating.
It is another advantage of the present invention that diluting the
polyfunctional
aziridine crosslinking agent significantly reduces the presence of
ethyleneimine and
propyleneimine, toxic components in the polyfunctional aziridine.
It is a feature of the present invention that coacervating agents, fillers,
nucleating
agents, and/or foaming agents can be added to the B-side when the
polyfunctional
aziridine crosslinking agent is diluted.
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It is a further feature of the present invention that the viscosity of the B-
side can be
reduced by diluting the polyfunctional crosslinking agent with a plasticizer
so that the B-side can
be easily pumped through a spray gun.
It is also a feature of the present invention that impurities in the benzoate
ester, such as
benzoic acid, neutralize the ethyleneimine in the polyfunctional aziridine
crosslinking agent.
It is yet another feature of the present invention that the foam acts as a
first defence for pest
control.
It is a further feature of the present invention that the foam is resistant to
cracking at
different application temperatures.
It is also a feature of the present invention that the foam compositions may
be used to fill
open or closed cavities or to fill cracks and crevasses.
The foregoing and other objects, features, and advantages of the invention
will appear more
fully hereinafter from a consideration of the detailed description that
follows.
DETAILED DESCRIPTION
Unless defined otherwise, all technical and scientific terms used herein have
the same
meaning as commonly understood by one of ordinary skill in the art to which
the invention belongs.
Although any methods and materials similar or equivalent to those described
herein can be used in
the practice or testing of the present invention, the preferred methods and
materials are described
herein. The terms "foamable composition" and "foam composition" may be
interchangeably used
in this application.
The present invention relates to two-part foamable compositions having an A-
side and a B-
side. The A-side of the foam composition includes a functionalizcd water-
dispersible and/or a
functionalized water-soluble resin (for example, a functionalized latex
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or a functionalized latex and an acrylic solution) and an acid and the B-side
contains a
polyfunctional aziridine crosslinking agent, a plasticizer, a base, and
optionally, a non-
reactive resin. The acid and the base together form a blowing agent package
that
generates a gas. The B-side may also contain coacervating agents, fillers,
nucleating
agents, and/or foaming agents. The inventive foams may be used to fill
cavities of
buildings to improve the sealing and insulation properties and to seal cracks
and crevasses,
such as those around windows and doors. Additionally, the foams may be used to
form
items such as cushions, carpet backing, mattresses, pillows, and toys. The
inventive foams
can be used in spray, molding, extrusion, and injection molding applications.
Further,
unlike conventional spray polyurethane foams, the foams of the present
invention do not
contain isocyanate. Therefore, no MDI monomers are present in the inventive
foams and
no harmful chemicals are emitted during installation of the foams.
As discussed above, the A-side of the composition for the foams includes a
functionalized water-dispersible and/or a functionalized water-soluble resin.
The
functionalized water-dispersible resin may be a functionalized latex, and in
exemplary
embodiments, the latex system is an acrylic emulsion. Non-limiting examples of
suitable
water-soluble resins for use in the inventive compositions include acrylic
solutions and
polyols. In addition to the functionalized water-dispersible and/or
functionalized water-
soluble resin, the serum can contain a polyacrylic oligomer to increase the
total number of
the functional groups. It is to be appreciated that although any
functionalized water-
soluble and/or functionalized water-dispersible resin(s) may be used as a
component in the
foamable compositions described herein, reference will be made to
functionalized latexes
with or without an acrylic solution.
There are numerous types of latexes that may be used as the functionalized
water-
dispersible component in the aqueous resin solution of the present invention.
Non-limiting
examples of suitable latexes include natural and synthetic rubber resins, and
mixtures
thereof, including thermosettable rubbers; thermoplastic rubbers and
elastomers including,
for example, nitrile rubbers (for example, acrylonitrile-butadiene);
polyisoprene rubbers;
polychloroprene rubbers; polybutadiene rubbers; butyl rubbers; ethylene-
propylene-diene
monomer rubbers (EPDM); polypropylene-EPDM elastomers; ethylene-propylene
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rubbers; styrene-butadiene copolymers; styrene-isoprene copolymers; styrene-
butadiene-
styrene rubbers; styrene-isoprene-styrene rubbers; styrene-ethylene-butylene-
styrene
rubbers; styrene-ethylene-propylene-styrene rubbers; polyisobutylene rubbers;
ethylene
vinyl acetate rubbers; silicone rubbers including, for example, polysiloxanes;
methacrylate
rubbers; polyacrylate rubbers including, for example, copolymers of isooctyl
acrylate and
acrylic acid; polyesters; polyether esters; polyvinyl chloride; polyvinylidene
chloride;
polyvinyl ethers; polyurethanes and blends; and combinations thereof,
including, for
example, linear, radial, star, and tapered block copolymers thereof In
exemplary
embodiments, the latex for use in the inventive foam composition is a
carboxylated acrylic
latex.
The water-dispersible and water-soluble resin may be functionalized. The
functional group may be any functional group capable of crosslinking,
including
carboxylic acid, hydroxyl, methylol amide groups, and sulfonates. In at least
one
exemplary embodiment, the water-dispersible and/or water-soluble resin(s)
contains from
about 1.0 to about 20 wt% functional groups based on the total wet weight of
the resin, or
from about 2.0 to about 15.0 wt% functional groups based on the total dry
weight of the
resin. The functionality of the functionalized water-dispersible and/or water-
soluble resin
can be adjusted by adding or removing functional groups to or from the resin
backbone to
reach the optimum amount of crosslinking and ultimately the optimum strength
and
modulus of the foam.
Additionally, the A-side contains at least one acid. The acid is placed in the
A-side
to avoid the inclusion of the acidic protons in the acid in the B-side and an
undesirable
pre-reaction of the polyfunctional aziridine crosslinking agent. The acid may
have a
solubility of 0.5 gil 00 g of water or greater at 30 C. In exemplary
embodiments, the acid
is a dry acid powder with or without chemically bound water. Non-exclusive
examples of
suitable acids include citric acid, oxalic acid, tartaric acid, succinic acid,
fumaric acid,
adipic acid, maleic acid, malonic acid, glutaric acid, phthalic acid,
metaphosphoric acid, or
salts that are convertible into an acid that is an alkali metal salt of citric
acid, tartaric acid,
succinic acid, fumaric acid, adipic acid, maleic acid, oxalic acid, malonic
acid, glutaric
acid, phthalic acid, metaphosphoric acid, or a mixture thereof. Examples of
salts which
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are convertible into acids include, but are not limited to, aluminum sulfate,
calcium
phosphate, alum, a double salt of an alum, potassium aluminum sulfate, sodium
dihydrogen phosphate, potassium citrate, sodium maleate, potassium tartrate,
sodium
fumarate, sulfonates, and phosphates. In exemplary embodiments, the acid is a
polymeric
acid. The acid(s) may be present in an amount from about 1.0 to about 30
percent by
weight of the dry foam composition, and in exemplary embodiments, in an amount
from
about 3.0 to about 20 percent by weight.
The B-side of the foam composition, as indicated previously, contains a
polyfunctional aziridine crosslinking agent, a plasticizer, a base, and
optionally, a non-
reactive resin. In particular, the non-reactive resin is a resin that does not
react with the
polyfunctional aziridine crosslinking agent, but is otherwise non-limiting.
Examples of
suitable polyfunctional amines include XAMA -7 and XAMA -2, tri-functional
aziridines
available from Bayer Corporation; Crosslinker CX-100, a polyfunctional
aziridine
available from DSM NeoResins; and XC-103, a trifunctional aziridine available
from
Zealchem. The polyfunctional aziridine crosslinking agent may be present in
the B-side in
an amount from about 3.0 to about 30 percent by weight of the dry foam
composition,
preferably in an amount from about 1.0 to about 20 percent by weight. Although
a mole
ratio of the resin functional groups to the polyfunctional aziridine
crosslinking agent
functional groups of 1:1 is preferred, this molar ratio is variable and may
encompass a
wider range, such as, for example, from 0.5:1 to 2:1 to provide the optimum
crosslinking
in the final foam products.
According to one aspect of the invention, the crosslinking agent is diluted by
a
plasticizer. The plasticizer should have no acidic protons to react with the
aziridine groups
in the crosslinking agent. Examples of suitable plasticizers for use in the B-
side of the
foamable composition include butyl benzoate, Benzoflex 2088 (a benzoate ester
plasticizer available from Genovique Specialties), Benzoflex LA-705 (a
benzoate ester
plasticizer available from Genovique Specialties), Triton(R) X-100 (an
octylphenoxypolyethoxyethanol available from Cognis), PEG-400 (a polyethylene
glycol
available from Cognis), Citroflex 2 (a triethyl citrate available from
Vertellus(
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Specialties), and Citroflex`g 4 (a tributyl citrate available from Vertellus8
Specialties). In
exemplary embodiments, the plasticizer is a benzoate ester or a citric acid
ester.
Diluting the polyfunctional aziridine crosslinking agent provides several
advantages. For example, the toxic components of the polyfunctional aziridine
can be
diluted with a small amount of benzoic acid in the benzoate ester to reduce
health risks to
those in contact with the polyfunctional aziridine. Polyfunctional aziridine
contains about
0.001% of ethyleneimine, which is very reactive moiety, and in theory, will
react with the
very small lcvel of acid impurities or water content of the other components
the B-side. In
addition, the viscosity of the B-side is reduced when the crosslinking agent
is diluted with
the plasticizer. As a result, the components of the B-side can be better mixed
with the
latex of the A-side in the spray gun to form an homogeneous mixture. Also, the
plasticizer
allows the foam composition to be delivered with standard plural component
spray
equipment, thereby negating the need for any specialized equipment.
Additionally, the presence of the plasticizer permits for the inclusion of
other solid
materials that may add functionality and/or cost savings to the final foamed
product. For
instance, coacervating agents, fillers (fin- example, calcium carbonate and
wollastonite
fibers), nucleating agents (for example, talc), and/or foaming agents (for
example, sodium
bicarbonate) can be included in the B-side of the foamable composition. It is
to be
appreciated that when the plasticizer and other components in the B-side do
not contain
any acidic protons, the B-side is stable for extended periods of time, such as
up to at least
six months or more.
As discussed above, the B-side contains at least one base that acts as an acid
sensitive chemical blowing agent. Generally, the weak base contains anionic
carbonate or
hydrogen carbonate, and, as a cation an alkali metal, an alkaline earth metal
or a transition
metal. Examples of bases suitable for use in the practice of this invention
include calcium
carbonate, barium carbonate, strontium carbonate, magnesium carbonate, lithium
carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium
carbonate,
calcium hydrogen carbonate, barium hydrogen carbonate, strontium hydrogen
carbonate,
magnesium hydrogen carbonate, lithium hydrogen carbonate, sodium hydrogen
carbonate,
potassium hydrogen carbonate, rubidium hydrogen carbonate, cesium hydrogen
carbonate,
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and bicarbonates and combinations thereof. In exemplary embodiments, the base
is
sodium bicarbonate. The base may be present in an amount from about 1.0 to
about 30%
by weight of the dry foam composition. In preferred embodiments, the base is
present in
the B-side in an amount from about 3.0 to about 20% by weight of the dry
foamable
composition. Sodium bicarbonate and citric acid in a ratio of 7:1 to 4:1 are
examples of a
base and acid acting as the blowing agent package in at least one exemplary
embodiment
of the invention.
In addition to the components set forth above, the A-side and/or the B-side
may
contain one or more surfactants to impart stability to the acrylic during the
foaming
process, to provide a high surface activity for the nucleation and
stabilization of the foam
cells, and to modify the surface tension of the latex suspension to obtain a
finely
distributed, uniform foam with smaller cells. Useful surfactants include
cationic, anionic,
amphoteric and nonionic surfactants such as, for example, carboxylate soaps
such as
oleates, ricinoleates, castor oil soaps and rosinates, quaternary ammonium
soaps and
betaines, amines and proteins, as well as alkyl sulphates, polyether
sulphonate (Triton
X200K available from Cognis), octylphenol ethoxylate (Triton X705 available
from
Cognis), octylphenol polyethoxylates (for example, Triton X110 available from
Cognis),
alpha olefin sulfonate, sodium lauryl sulfates (for example, Stanfax 234 and
Stanfax
234LCP from Para-Chemicals), ammonium laureth sulfates (for example, Stanfax
1012
and Stanfax 969(3) from Para-Chemicals), ammonium lauryl ether sulfates (for
example,
Stanfax 1045(2) from Para-Chemicals), sodium laureth sulfates (for example,
Stanfax
1022(2) and Stanfax (1023(3) from Para-Chemicals), and sodium sulfosuccinimate
(for
example, Stanfax 318 from Para-Chemicals). The surfactant may be present in
the A-
and/or B-side in an amount from about 0 to about 20% by weight of the dry foam
composition.
Further, the A-side and B-side may contain a thickening agent to adjust the
viscosity of the foam. It is desirable that the A-side and the B-side have the
same or
nearly the same viscosity to achieve the desired ratio of the A-side
components to the B-
side components. This permits for easy application and mixing of the
components of the
A-side and B-side. Suitable examples of thickening agents for use in the
foamable
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composition include calcium carbonate, methyl cellulose, ethyl cellulose,
hydroxyethyl
cellulose (for example, Cellosize HEC available from Union Carbide), alkaline
swellable
polyacrylates (fly example, Paragum 500 available from Para-Chem), sodium
polyacrylates (for example, Paragum 104 available from Para-Chem), glass
fibers,
cellulose fibers, and polyethylene oxide.
In at least one exemplary embodiment, the A-side contains one or more
components selected from a non-ionic urethane rheology modifier such as
AcrysolTM RM-
825, commercially available from Rhom and Haas; Optigel WX, an activated
smectite
product; and Laponite RD clay, a synthetic layered silicate available from
Southern Clay
Products, Inc. and the B-side contains at least one thickener selected from a
mixed
diamide thickening agent such as Thixatrol Max commercially available from
Elementis
Specialties and Garamite 1958, a mixed mineral thixotrope available from
Southern Clay.
The Laponite products belong to a family of synthetic, layered silicates
produced by the
Southern Clay Products Corporation.
As described above, it is desirable that the A-side and the B-side have the
same or
nearly the same viscosity to achieve the desired ratio of the A-side
components to the B-
side components to permit easy application and mixing of the components of the
A-side
and B-side. In at least one exemplary embodiment, a 4:1 ratio permits for easy
application
and mixing of the components of the A-side and B-side. The thickening agents
may be
present in the A-side and the B-side, respectively, in an amount up to about
50% by
weight of the dry foam composition. In at least one exemplary embodiment, the
amount
of thickening agent present in the A-side is from about 0.1 to about 10.0% by
weight,
based on the dry foamable composition, and the amount of thickening agent
present in the
B-side is from about 0.1 to about 10.0% by weight, based on the dry foamable
composition, depending upon the nature of the thickening agent.
An additional plasticizer may also be present in the A-side and/or B-side to
adjust
the viscosity of the foam. Non-limiting examples of suitable plasticizers
include phthalate
ester, dimethyl adipate, dimethyl phthalate, epoxidized crop oils (for
example, Drapex
10.4, Drapex 4.4, and Drapex 6.8 available from Chemtura). The plasticizer may
be
present in the foamable composition in an amount from about 0 to about 20% by
weight of
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the dry foam composition. Desirably, the plasticizer is present in an amount
from about 0
to about 15% by weight.
Further, an alcohol such as ethanol or isopropanol may be present in the foam
composition in the A-side and/or the B-side. The alcohol is preferably
miscible with water
and has a low boiling point. The alcohol acts as a co-solvent and replaces a
portion of the
water in the latex serum. Utilizing an alcohol co-solvent allows for a quicker
drying/curing time after the foam's application. Additionally, the co-solvent
assists in
creating a foam with a fine cell structure. Although not wishing to be bound
by theory, it
is believed that the higher vapor pressure of the alcohol causes the alcohol
to be driven off
more quickly than the water in the latex solution, and that the alcohol
carries the water
molecules as the alcohol is removed. The co-solvent is used in small
quantities, typically
from about 1.0 to about 5.0% by weight of the foam composition.
Depending on the type of particles used in the latex solution, the A- or B-
side may
also include other optional, additional components such as, for example, foam
promoters,
opacifiers, accelerators, foam stabilizers, dyes (for example, diazo or
benzimidazolone
family of organic dyes), color indicators, gelling agents, flame retardants,
biocides,
fungicides, algaecides, corrosion inhibitors, fillers (aluminum tri-hydroxide
(ATH)),
and/or conventional blowing agents. It is to be appreciated that a material
will often serve
more than one of the aforementioned functions, as may be evident to one
skilled in the art,
even though the material may be primarily discussed only under one functional
heading
herein. The additives are desirably chosen and used in a way such that the
additives do
not interfere with the mixing of the ingredients, the cure of the reactive
mixture, the
foaming of the composition, or the final properties of the foam.
To form a two-part spray foam of the present invention, the components of the
A-
side and the components of the B-side are delivered through separate lines
into a spray
gun, such as an impingement-type spray gun. The two components are pumped
through
small orifices at high pressure to form streams of the individual components
of the A-side
and the B-side. The streams of the first and second components intersect and
mix with
each other within the gun and begin to react. Depending on the components of
the
blowing agent package in the A-side and the B-side, the gas generated may be
CO?, N2,
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02, H2, or other non-carcinogenic gases. For example, the acid and the base
may react to
form carbon dioxide (CO2) gas. The foaming reaction occurs until all of the
blowing
agent(s) have been reacted and no more gas is generated.
In addition, the polyfunctional aziridine crosslinking agent reacts with the
acid and
with the functional groups on the acrylic to support the foamed structure.
Although not
wishing to be bound by theory, it is believed that the acid in the A-side
reacts with the
base in the B-side first and then with the polyfunctional aziridine
crosslinking agent. The
polyfunctional aziridinc also reacts with the functional groups positioned on
the latex.
The reaction of the polyfunctional aziridine with the acid and the latex to
form a polymeric
scaffolding-like structure (skeleton) that holds the foam structure while the
latex is
coagulating and hardening. The previously fluid/viscous foam material is
substantially
immobilized by the internal scaffolding-structure which prevents the foam from
collapsing. It is hypothesized that the use of a polymeric acid advantageously
provides for
a more flexible backbone in the polymeric structure. It is to be appreciated
that the
amount of functionality in the polyfunctional aziridine crosslinking agent,
the latex, and
the acid are adjusted to result in optimum crosslinking.
It is to be appreciated that the crosslinking is important for capturing the
bubbles
generated by the evolution of the gas in their original, fine structure before
they can
coalesce and escape the foam. A fine foam structure is more desirable and more
beneficial
than a coarse foam structure in order to achieve high thermal performance.
Additionally,
the crosslinking of the functional groups on the functionalized latex quickly
builds
strength in the foam and permits the foam to withstand the force of gravity
when it is
placed, for example, in a vertical wall cavity during application. The final
foamed product
becomes cured to the touch within minutes after application. The foamed
product has an
integral skin that restricts the passage of air but permits the passage of
water vapor. In
exemplary foamed products, the foam hardens within about 2 minutes. The
resulting
resistance to heat transfer, or R-value, may be from about 3.5 to about 8 per
inch.
In use, the inventive foams may be sprayed into either an open cavity, such as
between wall studs, or into a closed cavity where it expands to seal any open
spaces. The
application is desirably a continuous spray process. Alternatively, the foams
may be
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applied in a manner to fill or substantially fill a mold or fed into an
extruder or an injection
molding apparatus, such as for reaction injection molding (RIM), and used to
form items
such as cushions, mattresses, pillows, and toys. For example, a functionalized
water-
soluble or functionalized water-dispersible resin (for example, functionalized
latex or
functionalized latex and acrylic solution), a crosslinking agent, and a
blowing agent may
be mixed and applied to a mold where the crosslinking agent reacts with the
functionalized
resin while the blowing agent degrades or reacts to form a gas and initiate
the foaming
reaction.
The foams of the present invention may be used to insulate buildings such as
homes from temperature fluctuations outside of the building's envelope. The
foams may
serve both as a conductive and a convective thermal barrier. The foams of the
present
invention may also serve as a sealant or barrier to air infiltration by
filling cracks and/or
crevices in a building's roof or walls. Additionally, the foams may be used to
form a
barrier to seal cracks or crevasses around doors, windows, electric boxes, and
the like.
In addition, the foams of the present invention are preferably non-structural
foams.
The soft foam nature of the functionalized water-soluble and functionalized
water-
dispersible resins allows for easy compaction. As such, the inventive foams
have several
benefits. For example, there is no post-application waste to an open wall
cavity. If there
is an overfilling of the cavity, the drywall simply compresses the foam back
into the
cavity. The inventive foams are giving, so it will not apply a significant
pressure to the
drywall and little or no bowing or detachment of the drywall will occur.
Another advantage of the foams of the present invention is the safe
installation of
the foam into cavities. The foams do not release any harmful vapors into the
air when
applied or sprayed. Therefore, the inventive foams reduce the threat of harm
to
individuals working with or located near the foam. In addition, the
application of the
foams is more amenable to the installer as he/she will not need to wear a
special breathing
apparatus during installation.
Another advantage of the inventive foams is that it can be used in the
renovation
market, as well as in houses that are occupied by persons or animals.
Existing,
conventional spray polyurethane foams cannot be used in these applications
because of the
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generation of high amounts of free isocyanate monomers that could adversely
affect the
occupants of the dwelling. As discussed above, exposure of isocyanate monomers
may
cause irritation to the nose, throat, and lungs, difficulty in breathing, skin
irritation and/or
blistering, and a sensitization of the airways.
Yet another advantage of the present invention is that the toxic components of
the
polyfunctional aziridine can be diluted with a plasticizer(s) to reduce health
risks to those
in contact with the polyfunctional aziridine. The acid impurities of the
plasticizer react
with the toxic ethyleneimine to neutralize it and make the foam safe for those
in contact
with the foam. In addition, diluting the polyfunctional aziridine crosslinking
agent
reduces the viscosity of the B-side so that the components of the B-side can
be better
mixed with the latex of the A-side in the spray gun. Also, the plasticizer in
the B-side
permits the foam composition to be delivered with standard plural component
spray
equipment, thereby negating the need for any specialized equipment.
It is further advantageous that the inclusion of the plasticizer in the B-side
allows
for the inclusion of other solid materials that may add functionality and/or
cost savings to
the final foamed product. Additionally, the B-side is stable for extended
periods of time as
long as there are no acidic protons present in the B-side components.
It is also an advantage of the present invention is that the components of the
one-
part or two-part foam compositions are carefully chosen to result in a tacky
or sticky foam
that can be used to hold the fiberglass batt in place when used to fill cracks
or crevasses.
Having generally described this invention, a further understanding can be
obtained
by reference to certain specific examples illustrated below which are provided
for
purposes of illustration only and are not intended to be all inclusive or
limiting unless
otherwise specified.
EXAMPLES
Example 1:
The polyfunctional aziridine XAMAR-7 was tested for the presence of
ethyleneimine (aziridine) or propyleneimine (methyl aziridine). Samples 1 and
2 were
duplicate neat samples of XAMAc)-7.
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A sample of approximately 200 mg was placed inside a 25 ml headspace vial. The
sample vial was equilibrated at 150 C for 30 minutes. After equilibration,
dual needles
were inserted into the headspace volume and the entire contents were swept
onto a Vocarb
3000TM trap that was maintained at 27 C. After 5minutes of sweeping the
headspace, the
trap was thermally desorbed at 270 C. Volatiles from the trap were swept onto
a 30 meter
fused silica HP-624 capillary column that was attached to a mass selective
detector. The
column oven was temperature programmed from 35 C to 240 C at a rate of 10
C/minute
with initial and final column temperature held for 5 minutes. Data was
collected on full
scan mode. The results are set forth in Table 1.
Table 1:
Estimation of Aziridine Concentration in the Headspace Vial
Sample Integrated
Aziridine in 25 ml
Sample Weight Area igIg
Headspace
(g) (TIC)
Volume
Sample
0.23646 525,742,251 16.0 66
1
Sample
0.22408 520,639,335 15.8 71
2
It was determined that there was no ethyleneimine (aziridine) or
propyleneimine
(methyl aziridine) present in a sample that contained the B-side components
(not indicated
in Table 1). In addition, there was no indication that propyleneimine (methyl
aziridine)
was present in either Sample 1 or Sample 2. There was, however, a high
concentration of
ethyleneimine (aziridine) in each of the samples of the XAMA -7. As discussed
above,
ethyleneimine is a toxic substance. This analysis shows that although an
average of
approximately 69 i.tg/g of ethyleneimine (aziridine) is present in the
headspace of neat
XAMA -7 at 150 C, the headspace of the B-side components is free of
ethyleneimine
(aziridine). It is hypothesized that this absence of ethyleneimine (aziridine)
in the B-side
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is partly due to the dilution factor itself partly due to the fact that the
ethyleneimine
(aziridine) reacts quickly with the acid impurities and small water content of
the other
components in the B-side.
Example 2:
A sample of a mixture of XAMA -7 (polyfunctional aziridine) and Benzoflex
2088 (a benzoate ester plasticizer available from Genovique Specialties) in a
ratio of 2:1
was tested to determine if ethyleneimine (aziridine) or propyleneimine (methyl
aziridine)
was present.
A portion of the sample (approximately 100 mg) was placed inside a 25 ml
headspace vial. The sample vial was equilibrated at 80 C for 15 minutes.
After
equilibration, dual needles were inserted into the headspace volume and the
entire contents
were swept onto a Vocarb 3000Tm trap that was maintained at 27 'C. After 10
minutes of
sweeping the headspace, the trap was thermally desorbed at 270 C. Volatiles
from the
trap were swept onto a 30 meter fused silica HP-624 capillary column that was
attached to
a mass selective detector. The column was temperature programmed from 35 C to
240 C
at a rate of 10 C/minute with initial and final column temperature held for 5
minutes.
Data was collected in full scan mode. The results are set forth in Table 2.
Table 2:
Estimation of Aziridine Concentration in the Headspace Vial
Sample
Aziridine in 25 ml
Sample Weight fig/g
Headspace
(g)
Volume
Benzoflex 2088a 0.306 <0.01 <0.03
a - a benzoate ester plasticizer available from Genovique
Specialties
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As shown in Table 2, the concentration of ethyleneimine (aziridine) was
determined to be less than 0.03 litg/g. It is believed that the concentration
of ethyleneimine
(aziridine) present in the sample is lowered, partly due to the dilution
factor itself and
partly due to the fact that the ethyleneimine (aziridine) reacts quickly with
the small
quantities of acid and water present in the Benzoflex 2088 as impurities.
The invention of this application has been described above both generically
and
with regard to specific embodiments. Although the invention has been set forth
in what is
believed to be the preferred embodiments, a wide variety of alternatives known
to those of
skill in the art can be selected within the generic disclosure. The invention
is not
otherwise limited, except for the recitation of the claims set forth below.
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