Note: Descriptions are shown in the official language in which they were submitted.
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IN-SITU POLYMERIZATION OF BONDED FOAM ADHESIVES
This application claims the benefit of U.S. Provisional Application Serial No.
60/279,013, filed on March 27, 2001.
BACKGROUND OF THE INVENTION
The conventional method of manufacturing bonded foam entails supplying
isocyanate, polyol and optional processing oil to a reactor to produce a
prepolymer. The
prepolymer then is blended with flexible foam crumb, as an adhesive. The
resulting mass of
adhesive (prepolymer) treated foam crumbs is molded under pressure and steam
is
simultaneously injected to cure the prepolymer and to produce a bonded foam
product.
The conventional method described above has several disadvantages. These
disadvantages include, for example, improper blending of components which
results in a
gelled polymer inside the reactor, moisture ingress into the prepolymer
reactor which can
1 S cause solid reacted polymer to form in the reactor, and premature
reactivity of the prepolymer
with ambient moisture before the compression molding stage can reduce the
tensile strength
of the bonded foam. Separation of the components of the prepolymer, especially
the diluent
process oil, may occur in the conventional process. This bulk separation of
the prepolymer
causes serious handling and storage problems. Another serious disadvantage of
the
conventional foam re-bonding process concerns the use of steam as the curative
agent for the
prepolymer adhesive. The steam adds large quantities of moisture to the re-
bonded foam
product, which must subsequently be dried out of the product before the
product can be used
or packaged. This drying operation can be energy intensive. It also wastes
time, floor space,
and adds to the complexity of the overall process.
Additional disadvantages associated with the conventional method described
above
include restrictions on starting materials. The polyol employed typically is a
nominal triol
that has a number averaged molecular weight in the range of 3,000 to 3,500.
Use of polyols
which are significantly outside this molecular weight range can cause problems
in managing
the viscosity and physical stability of the prepolymer. Moreover, the
prepolymer is restricted
to an isocyanate value of approximately 7% or greater due to constraints on
the viscosity of
the prepolymer which can be employed in the conventional method of the prior
art. The
viscosity restrictions at low isocyanate values are especially severe with MDI
based
prepolymers. MDI based isocyanates are becoming increasingly preferred in the
foam re
bond industry for health and environmental reasons. This is because they have
lower vapor
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pressures than TDI isocyanates. The limitations, imposed by viscosity
considerations, on the
minimum free isocyanate content of the prepolymer places serious restrictions
on the range of
adhesive properties that may be achieved. For example, if the free isocyanate
content of the
prepolymer is too high, then the adhesive will be too rigid and brittle upon
curing. The
S purpose of the polyol component in the adhesive is to impart flexibility to
the adhesive bond.
The prepolymer method imposes restrictions on the amount of this flexibilizing
polyol which
may be incorporated into the adhesive. In general, in order to be processable,
the prepolymer
must have a viscosity of less than about 4000 cps at 25°C.
A need therefore exists for adhesives which can be used to produce bonded
foam, and
methods of producing bonded foam which avoid the disadvantages of the prior
art
prepolymer method. It would be particularly desirable not to have to make
prepolymers at
all, but to find another way of incorporating the flexibilizing polyol
ingredient into the'
adhesive composition which can accommodate any ratio of polyol to base
(monomeric)
polyisocyanate. Ideally, it would be desirable to be able to cure the
adhesives without steam
or added moisture.
SUMMARY OF THE INVENTION
There is disclosed an improved method for re-bonding foam crumbs with an
isocyanate based adhesive composition. The adhesive composition comprises a
plurality of
separate reactive components including at least one organic polyisocyanate
component and at
least one organic isocyanate reactive component, wherein the separate reactive
components
are applied to a single mass of foam crumbs before the reaction between the
separate
components is substantially completed. The method of the invention overcomes
the
limitations associated with the use of single component isocyanate terminated
prepolymer
adhesives.
DETAILED DESCRIPTION OF THE INVENTION
Glossary:
As used herein, the following terms have the meanings defined below:
1. Calight RPO is naphthenic oil from Calumet Lubricants;
2. Calsol~ 806 is naphthenic oil from Calumet Lubricants;
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3
3. DABCO~ 33LV is 33% triethylene diamine in dipropylene glycol available
from Air Products;
4. Dabco~ 120 is a tin catalyst from Air Products, Inc.;
5. Dabco~ 8154 is acid blocked Dabco 33LV available from Air Products;
6. Dabco~ T-45 is a potassium carboxylate catalyst formulation from Air
Products and Chemicals, Allentown, PA;
7. JEFFOL~ PPG-3704 polyol is an EO tipped diol with a molecular weight of
3700 from Huntsman Polyurethanes.
8. RUBINATE~ 9041 isocyanate is a blend of 75% RUBINATE~ M isocyanate
and 25% of an MDI isomer blend having 80% 4,4'MDI and 20% 2,4'MDI;
9. RUBINATE~ M isocyanate is polymeric MDI from Huntsman Polyurethanes
having an isocyanate value of 31.5% by weight and a functionality of 2.7;
10. RUBINOL~ F459 polyol is a polyether polyol from Huntsman Polyurethanes
with a hydroxyl number of 30 and a nominal functionality of 2;
11. Sundex~ 840 is an aromatic oil from Sun Oil Company;
12. Voranol~ 3512 is polyether polyol from Dow Chemical Company with a
hydroxyl number of 48.1 and a nominal functionality of 3;
13. Over Index means a stoichiometric ratio of NCO:active -H groups > 1;
14. Under Index means a stoichiometric ratio of NCO:active -H groups < 1;
15. The functionalities and molecular weights of polymeric compounds are
number
averaged, unless otherwise specified. The functionalities and molecular
weights of pure
compounds are absolute, unless otherwise specified.
16. The term "nominal functionality" refers to the assumed functionality of a
polymeric species (such as a polyol) based on the functionality of its
monomers, ignoring
side reactions. For example, the nominal functionality of a polyoxyalkylene
polyol is the
functionality of its initiator.
The invention relates to adhesive compositions comprising a plurality of
reactive
components, and methods of producing bonded foam crumb products therefrom. All
of the
components are preferably liquids at the temperature of application, and more
preferably all
the components are homogeneous liquids at ambient temperature. Advantageously,
the
multicomponent adhesive compositions can be directly or catalytically
polymerized in-situ on
the foam crumb without the need to use an intermediate prepolymer. The in-situ
polymerization may be accomplished with steam, electromagnetic energy, or hot
air. The
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adhesive compositions of the invention are not restricted by isocyanate value
or prepolymer
viscosity as in the prior art. Moreover, the prior art requires that an "A-
side" (isocyanate
component) and a "B-side" (polyol component) be separately prepared, mixed
together, and
then added to the foam crumbs. In an aspect of the invention, each component
used can be
added directly into a mass of foam crumbs without the need for making an A-
side and B-side.
The use of moisture or steam to cure the adhesive is not required, and is
generally less
preferred than other methods of cure (such as the use of hot air or
electromagnetic radiation).
In addition to the above noted advantages, the multicomponent adhesive
compositions
of the invention are less constrained, as compared to the prior art, in regard
to the ranges of
molecular weight or functionality of the flexibilizing polyols or the
monomeric (base)
polyisocyanates which can be used. Likewise, the flexibilizing polyol and the
monomeric
(base) polyisocyanate can be combined in virtually any desired ratio by using
the
multicomponent approach according to the invention. Moreover, if the energy
source for
curing the multicomponent adhesive is hot air or electromagnetic energy, then
the need for an
extra process step to remove moisture from the cured re-bond foam product is
eliminated.
In an aspect of the invention, an isocyanate, polyol and optional oil are
mixed in the
presence of a metal catalyst and/or an amine type catalyst to produce an
adhesive
composition which can be polymerized with or without steam. The adhesive
compositions
are particularly suited for bonding of polyurethane foam crumb. The adhesive
according to
the invention is formulated and can be applied to the foam crumbs as two or
more separate
reactive components. The preferred mode is to use two separate reactive
components,
although any number of reactive components may be used if desired. In this
preferred mode,
the flexible polyol and the catalyst are combined into one component. The
second
component is the monomeric (base) polyisocyanate. The optional process oil, if
used, may be
combined with either or both of these two reactive components. The separate
reactive
components of the multicomponent adhesive may be added simultaneously or
separately to
the same mass of foam crumbs, in any desired overall amounts, or in any ratio
with respect to
each other. It is preferred that all the separate reactive components are
added to the same
mass of foam crumbs to be bonded. In a preferred mode all the reactive
components are
added simultaneously to the same mass of foam crumbs. In another embodiment
the
separate reactive ingredients may be pre-mixed immediately before application
to the foam
crumbs, under the proviso that significant reaction of the separate components
does not occur
in the pre-mix before the pre-mix is applied to the foam crumbs. If such a pre-
mix is used,
then less than 50% of the reactive isocyanate or isocyanate-reactive
functional groups
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initially present should have reacted before the pre-mix is applied to the
foam crumbs,
preferably less than 40%, more preferably less than 30%, still more preferably
less than 25%,
and most preferably less than 20%. If the reaction of the separate ingredients
in such a pre-
mix is too far advanced at the time of application, it may become physically
impossible to
S apply the adhesive to the foam crumbs. If this reaction is too far advanced
at the time the
adhesive treated foam crumbs are compressed in the mold, then the adhesive may
not bond
the foam particles effectively and a poor quality product will result.
A particularly advantageous variant of the pre-mix method is to employ a
multicomponent metering machine to meter together and mix the various
components of the
adhesive and then immediately apply the reacting mixture to the mass of foam
crumbs. The
reacting mixture may, for example, be applied to the foam crumbs by spraying
or by means
of a spinning disk applicator. The foam crumbs thus treated may preferably be
tumbled while
the reacting adhesive mixture is applied, or immediately thereafter, in order
to maximize the
distribution of the adhesive onto the foam crumbs.
A further advantage of the present invention is that bonded foam crumb
products can
be produced in surprisingly short cycle times. In this regard curing of the
adhesive
composition can occur in less than 30 minutes (measured from the time the
press is closed)
with or without the application of steam. More preferably curing occurs in
less than 1 S
minutes and even more preferably curing can occur in less than 10 minutes. In
an aspect of
the invention curing of the adhesive can occur in from 1 to 10 minutes and,
more preferably,
in from 3 to 5 minutes.
MATERIALS:
Isocyanate Component:
The multicomponent adhesives of the invention comprise at least one isocyanate
component. The isocyanate component comprises at least one organic compound
wherein
the organic compound contains a plurality of isocyanate groups. The preferred
isocyanate
compounds are monomeric (base) polyisocyanates.
Organic monomeric polyisocyanates which are useful as the isocyanate
components
in the context of the invention include aromatic, aliphatic and cycloaliphatic
diisocyanates
and polyisocyanates and combinations of these types.
Aromatic diisocyanates which may be used include 4,4'MDI, 3,3'-dimethyl-4,4'-
diphenylenediisocyanate, 3,3'-dimethoxy-4,4'-bisphenylenediisocyanate, 3,3'-
diphenyl-4,4'-
biphenylenediisocyanate, 4,4'-biphenylene diisocyanate, 4-chloro-1,3-phenylene
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diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, toluene
diisocyanate, and 1,5-
naphthalene diisocyanate. MDI isocyanates are preferred. Polymeric MDI having
about
31.5% NCO and about 2.7 functionality is most preferred. Polymeric MDI is a
combination
of monomeric isocyanates which includes 4,4'-MDI, lesser amounts of 2,4'-MDI,
minor
amounts of 2,2'-MDI, and a mixture of higher functionality polymethylene
polyphenyl
polyisocyanate oligomers. The preferred polymeric MDI has a number averaged
isocyanate
functionality of 2.7, due to the presence of the mixed high functionality
polymethylene
polyphenyl polyisocyanate monomer species. Polymeric MDI is prepared by the
phosgenation of mixed aromatic amines obtained from the condensation of
aniline with
formaldehyde. The preparation of polymeric MDI is well known in the art. It is
also within
the invention to use blends of polymeric MDI with additional amounts of
diphenylmethane
diisocyanates, particularly 4,4'-MDI. These blends will have number averaged
isocyanate
functionalities of from greater than 2.0 up to about 2.7, depending upon the
ratio of the
diphenylmethane diisocyanates to the polymethylene polyphenyl polyisocyanates
in the
blend.
Aliphatic isocyanates which may be employed include but are not limited to
ethylene
diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate
(HDI), 2,4,4-
tri-methyl-1,6-hexamethylene diisocyanate, and 1,12-dodecane diisocyanate.
Cycloaliphatic isocyanates which may be employed include but are not limited
to
cyclohexane-1,4-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-
diisocyanate,
1-isocyanato-2-isocyanatomethyl cyclopentane, 1-isocyanato-3,3,5-trimethyl-5-
isocyanatomethyl cyclohexane (isophorone diisocyanate or IPDI), 2,4'-
dicyclohexylmethane
diisocyanate, 4,4'-dicyclohexylmethane diisocyanate.
Although it is preferred not to use prepolymers in this invention, it is
within the scope
of the invention to use as one or more components of the multicomponent
adhesive
composition an isocyanate terminated prepolymer. If an isocyanate terminated
prepolymer is
used as a component of the adhesive formulation, it is preferable that the
prepolymer have a
relatively high free isocyanate content. Preferably the prepolymer, if used at
all, has an free
isocyanate content of greater than 10% by weight, and more preferably greater
than 15% by
weight.
Isoc~anate Reactive Component:
The multicomponent adhesive formulations of the invention comprise at least
one
isocyanate reactive component. The isocyanate reactive component contains at
least one
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organic compound having a plurality of isocyanate reactive groups. The
preferred isocyanate
reactive compounds are polyols. The isocyanate reactive component may
optionally include
water in addition to the organic isocyanate reactive ingredients, although it
is preferable not
to include water.
Suitable organic polyols useful for making the adhesive compositions of the
invention
include polyether, polyester, or amine polyols having a molecular weight range
of about 50 to
about 15,000 and a nominal functionality of about 1.0 to about 7.0, preferably
polyether
polyols with a molecular weight range of about 50 to about 6,000 and a nominal
functionality
of about 2.0 to about 3Ø Examples of useful polyols include but are not
limited to ethylene
glycol, propylene glycol, dipropylene glycol, tripropylene glycol, diethylene
glycol,
triethylene glycol, glycerol, trimethylolpropane, triethanolamine,
diethanolamine,
triisopropanolamine, diisopropanolamine, butanediol, butenediol, butynediol, N-
methyl
diethanolamine, Rubinol~ F459, Rubinol~ F455 (both from Huntsman
Polyurethanes) Arcol~
3022, Arcol~ 3128 (both from Lyondell Corporation), Voranol~ 220-028 (from Dow
Chemical Corporation) and Pluracol~ P-2010 (from BASF Corporation). Other
isocyanate
reactive active hydrogen containing species which may be used include, but are
not limited
to, diethyltoluene diamine, and N-N,-di-sec-butyl-4,4'-diaminodiphenylmethane.
Simple
polyols, containing only organic -OH groups as reactive termini, are
preferred. The most
preferred polyols contain primary or secondary -OH groups. Primary -OH groups
are most
preferred.
Rigid polyols also may be employed. Examples of rigid polyols which may be
employed include but are not limited to Rubinol~ 8015, Rubinol~ 8180, and
Rubinol~ 8260.
(from Huntsman Polyurethanes). These polyols have a functionality of about 2
to about 7
and a molecular weight from about 200 to about 1000.
The preferred polyols are flexible polyols, which contribute a flexibilizing
effect to
the cured adhesives. Useful flexible polyols have a molecular weight of about
300 to about
10,000, preferably 400 to about 8000, more preferably 1000 to about 6000, and
a nominal
functionality of about 1.0 to about 6.0, preferably about 2.0 to about 4Ø
Examples of flexible
polyols which may be employed include, but are not limited to, Rubinol~ 459
and Rubinol~
455 (from Huntsman Polyurethanes).
Polyether and polyester flexible polyols which may be employed include primary
or
secondary hydroxyl groups.
Suitable polyether polyols which can be employed as the isocyanate reactive
component include those which are prepared by reacting alkylene oxides,
halogen-substituted
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or aromatic-substituted alkylene oxides or mixtures thereof with an active
hydrogen-
containing initiator compound.
Suitable oxides include, for example, ethylene oxide, propylene oxide, 1,2-
butylene
oxide, styrene oxide, epichlorohydrin, epibromohydrin, and mixtures thereof.
Suitable initiator compounds include water, ethylene glycol, propylene glycol,
butanediol, hexanediol, glycerine, trimethylol propane, pentaerythritol,
hexanetriol, sorbitol,
sucrose, hydroquinone, resorcinol, catechol, bisphenols, novolac resins,
phosphoric acid and
mixtures thereof.
Suitable initiators further include, for example, ammonia, ethylenediamine,
diaminopropanes, diaminobutanes, diaminopentanes, diaminohexanes,
diethylenetriamine,
triethylenetetramine, tetraethylenepentamine, pentamethylenehexamine,
ethanolamine,
aminoethylethanolamine, aniline, 2,4-toluenediamine, 2,6-toluenediamine, 2,4'-
diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 1,3-phenylenediamine, 1,4-
phenylenediamine, naphthylene-1,5-diamine, triphenylmethane 4,4',4"-triamine,
4,4'-
di(methylamino)diphenylmethane, 1,3-diethyl-2,4-diaminobenzene, 2,4-
diaminomesitylene,
1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-
diaminobenzene, 1,3,5-
triethyl-2,6-diaminobenzene, 3,5,3', 5'-tetra-ethyl-4,4'-diamino-
diphenylmethane, and amine
aldehyde condensation products such as the polyphenylpolymethylene polyamines
produced
from aniline and formaldehyde and mixtures thereof.
Polyester polyols which may be employed include, for example, those prepared
by
reacting a polycarboxylic acid or anhydride with a polyhydric alcohol. The
polycarboxylic
acids may be aliphatic, cycloaliphatic, aromatic and/or heterocyclic and may
optionally be
substituted (e.g., with halogen atoms) and/or unsaturated. Examples of
suitable carboxylic
acids and anhydrides include succinic acid, adipic acid, suberic acid, azelaic
acid, sebacic
acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid,
phthalic acid
anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid
anhydride,
tetrachlorophthalic acid anhydride, endomethylene tetrahydrophtalic acid
anhydride, glutaric
acid anhydride, malefic acid, malefic acid anhydride, fumaric acid, dimeric
and trimeric fatty
acids, such as those of oleic acid, which may be in admixture with monomeric
fatty acids.
Simple esters of polycarboxylic acids may also be used as starting materials
for polyester
polyols , such as terephthalic acid dimethyl ester, terephthalic acid
bisglycol ester and
mixtures thereof.
Typically, polyether nominal triols or polyester nominal triols which have a
molecular
weight of about 3,000 to about 3,500 are used. Diols may also be used. Blends
of these
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polyols also may be employed. Polyether polyols are more preferred. The most
preferred
polyether polyols are based on propylene oxide, optionally in combination with
minor
amounts of ethylene oxide. Examples of these most preferred types of polyether
polyols
include Arcol~ 3022 (from Lyondell Corporation) and Voranol~ 3512 (from Dow
Chemical
Corporation).
Examples of amine terminated polyols which may be employed include but are not
limited to JEFFAMINE~ amine terminated polyether polyols from Huntsman
Petrochemicals
Corporation.
Mixtures of different polyols may optionally be used. For example, mixtures of
relatively high molecular weight polyols and relatively low molecular weight
di or
polyfunctional active hydrogen compounds may be used as an isocyanate reactive
component
in the practice of the invention.
The multicomponent adhesive compositions employed in the invention may
comprise
a catalyst for the reaction of the isocyanate reactive component with the
isocyanate
component. The catalysts may not be essential in all cases, but are usually
preferred. In a
particularly preferred embodiment the catalyst is blended together with all
isocyanate reactive
ingredients to form a single isocyanate reactive component.
Suitable catalysts for use in the adhesive formulations of the invention
include but are
not limited to triethylene diamine, bis-2-(N,N-dimethylamino)-diethyl ether, 2-
(N,N-
dimethylamino) ethanol, N-hexadecyl dimethylamine, N,N-dimethylamino
propylamine,
triethanolamine, triisopropanolamine, N,N-dimethyl cyclohexylamine, 3-(N,N-
dimethyl
amino)-propionamide, dibutyl tin dilaurate, alkyl tin mercaptide complexes, 2-
ethyl hexanoic
acid (octoic acid) potassium salt, potassium acetate, potassium oleate,
combinations of these,
and the like. The catalysts may also include acid blocked amines, an example
of which is
Dabco~ 8154 (from Air Products and Chemicals Corporation). A preferred
catalyst for use in
combination with hot air curing is Dabco~ T-45. This catalyst is believed to
be a solution of
potassium 2-ethyl hexanoate in dipropylene glycol, and is commercially
available from Air
Products and Chemicals Corporation. In the case of triethanolamine,
triisopropanolamine,
and other tertiary amine initiated polyols, the polyol and the catalyst
ingredients may be the
same chemical species.
Suitable diluents for use in the adhesive formulations of the invention
include but are
not limited to processing oils such as naphthenic, aromatic, and paraffinic
oils, natural oils
such as vegetable oils, or any blend of these. Napthenic process oils are
preferred. Suitable
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diluents may include methylene chloride, ketone-based solvents, propylene
carbonate,
mixtures of these, and the like.
In a particularly preferred embodiment of the invention there are only two
components to the adhesive system used. One component is a monomeric (base)
5 polyisocyanate composition. The other component is a blend of all the liquid
or soluble
isocyanate reactive compounds, catalysts, diluents, and any additional
optional additives to
the adhesive. Both components are preferably homogeneous liquids at ambient
temperature
(i.e., 25°C). It is, however, within the scope of the invention to use
one or more liquid
components that are not fully homogeneous, with the proviso that any
inhomogeneous
10 ingredients are dispersed in a liquid component.
The relative proportions of the various components of the multicomponent
adhesive
system, and of the various ingredients to each component, may be adjusted in
order to fine
tune the properties of the final adhesive bonded foam product. A particularly
advantageous
feature of the instant invention is the absence of restrictions imposed due to
handling
requirements of the relative amounts of isocyanate and isocyanate reactive
monomers that
may be employed in the adhesive composition of the invention. Indeed, the
effective
"isocyanate index" (also known as "Index") of the adhesive formulation may
take on any
value. The isocyanate index is the ratio of isocyanate groups to isocyanate
reactive groups in
the formulation, and is usually expressed as a percent. A value of greater
than 100% means
that excess isocyanate is used (referred to as "over index"). A value of less
than 100% means
that excess isocyanate reactive material is used (referred to as "under
index"). A value of
100% is indicative of an exact stoichiometric balance between the isocyanate
and isocyanate
reactive material in the adhesive formulation. Good re-bonded foam products
can be
prepared by using the multicomponent adhesives of the invention, at index
values of less than
100%, at greater than 100%, or at exactly 100%. By contrast, using the prior
art one-
component (isocyanate terminated prepolymer) rebond adhesives, it is only
possible to make
re-bonded foam products at index values considerably above 100%. These prior
art systems
depend on moisture (usually in the form of steam) to react out the excess
isocyanate groups
present. This can result in undesirable properties (due to the high levels of
urea linkages
present in the cured adhesive) and problems with drying the re-bonded foam
product, as
described hereinabove.
Additional ingredients can be included in the adhesive formulations of the
invention.
Examples of these additional ingredients include but are not limited to non-
reactive chemicals
such as trischloropropylphosphate or other fire retardants, dyes or colorants,
wood or
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11
cellulosic fibers, rubber or elastomer particles, other inert fillers,
mixtures of these and the
like. These optional additional inert ingredients, if used at all, may be pre-
mixed with any of
the essential ingredients in any desired proportion prior to forming the
reacting adhesive
mixture. They may alternatively be combined with the other ingredients in the
final mixing
step, just prior to application of the reaction mixture to the foam crumbs.
The adhesive formulations may be employed with a variety of foam crumb types
to
produce bonded foam crumb products. Examples of types of foam crumb which may
be used
include polyether urethane foam crumb, polyester urethane foam crumb, reground
rebond,
cloth and foam from automotive recyclate, bedding process scrap, rubber
process scrap,
I O molded foam process scrap, post-consumer recyclate, slabstock process
scrap. Blends of
different types of foam crumb also may be used. Examples of useful foam blends
include
rigid foam with flexible foam, polyether urethane based foam with polyester
urethane based
foam and polyisocyanurate based foam.
The foam crumbs may also be combined with other solid additives prior to or
15 simultaneously with the application of the adhesive composition. Solid
additives to the foam
crumbs may include solid fire retardants such as melamine, ammonium
polyphosphate,
antimony oxide, alumina trihydrate, mixtures of these, and the like. The foam
crumbs may
also be combined with cellulosic or lignocellulosic particulate or fibrous
materials as
extenders. The foam crumbs may also be extended with inorganic fibrous
materials such as
20 glass fibers, glass mats, mineral wool, and the like. Likewise, the foam
crumbs may be
combined with organic fibrous materials such as textile scraps, carpet scraps,
and the like.
Also, it has been found effective to add calcium carbonate to the foam crumbs
to increase the
density of the obtained foam pad.
The invention will now be described by reference to the following non-limiting
25 examples. All amounts are expressed in weight percent based on the total
weight of the
composition.
EXAMPLES:
One composition of an adhesive according to the invention is shown below as
30 Adhesive A. It can be prepared by hand mixing 50 grams (total of all
components used to
form the adhesive) of adhesive with a tongue depressor, for about 10 seconds
in a 4 ounce
paper cup. The isocyanate can be added in an amount appropriate to produce the
desired
Index. In an aspect of the invention, all of the components can be added to
the foam crumb at
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12
the same time, thus eliminating the need for first forming an A-side and B-
side, combining
the A-side and B-side, and then adding the combined A-side and B-side to the
foam crumbs.
The following components can be used to produce Adhesive A:
Component Parts by wt.
RUBINATE~ 9041 isocyanate variable, depending on desired Index.
Voranol~ 3512 polyol 72.3
Dipropylene glycol 3.8
Dabco T45 catalyst 2.4
Caught RPO 21.5
Examples 1-15:
The components of each adhesive mixture were separately added to a cup and
mixed
with a tongue depressor for about 10 seconds until a homogeneous mixture was
obtained.
The adhesive mixtures in~Examples 1-3 and 8-15 were applied to the foam crumb
within 30
seconds after the completion of mixing. The adhesive mixtures in Examples 4-7
were
prepared by adding the components to a cup, mixing the components, and then
storing the
mixture in an oven (40°C) for about 14 hours. The adhesive mixture was
then removed from
the oven and slowly poured over the foam crumb. The foam crumb was weighed and
then
transferred to a 30 gallon drum which served as a mixing vessel. A mixer blade
was placed
into the drum so that the mixer blade was about 1 inch from the bottom of the
drum. The
mixer was turned on to a rotation speed of about 282 rotations per minute and
the mass of
adhesive was slowly poured over the foam crumb. The foam crumb and adhesive
were
mixed for about 80 seconds. After about 80 seconds, the mixer was turned off
and removed
from the drum. The foam crumb coated with adhesive was then transferred to a
mold where
the foam crumb/adhesive mass was compressed and cured, as discussed below.
In each of the following Examples, 76 grams of the adhesive is blended with
683
grams of foam crumb formed from a mixture of virgin polyether based
polyurethane foam
(about 546.4 grams), virgin polyester based polyurethane foam (about 102.5
grams), and
reground rebond polyurethane foam (about 34.1 grams). The mixture of foam
crumb and
adhesive is compressed to form a block. Specifically, the mixture of foam
crumb and
adhesive is transferred to an about 17 inch by 17 inch aluminum mold. The
mixture is then
compressed using a mold plunger to an about two inch height and cured.
CA 02440608 2003-09-04
WO 02/077083 PCT/US02/08753
13
The preferred amount of the adhesive of the invention is 10% by weight (in 90%
by
weight foam crumb). Adhesive is typically used at between 5% - 15% by weight
in the re-
bond foam industry.
In the examples below, the mixture of foam crumb and adhesive is compressed in
the
mold. The mold includes solid horizontal walls with perforated top and bottom
plates. The
perforated plates allow penetration of air or steam into the compressed foam
sample, to
promote cure of the adhesive. When air is employed for curing, the temperature
of the air
can vary from ambient up to about 170°C, preferably about 130°C.
The steam can be
employed at ambient pressure or in an autoclave under a range of temperatures
and pressures.
Examples 1-3 were generated using hot-air curing. Specifically, a heat gun
(Master
heat gun - model HG-751B, available from Master Appliance Corporation) was
used to apply
hot air to the compressed foam crumb/adhesive mixture. The heat gun was cycled
as follows:
5 seconds of heating mixture and 15 seconds without heat. This cycling was
repeated for 7
minutes and then the foam was demolded.
Examples 4-15 illustrate the resulting physical properties of re-bonded foam
generated with conventional adhesives and adhesives according to the
invention. All of these
samples were cured with steam. Examples 8-11 show the resulting physical
properties of the
adhesives made with an aromatic diluent. Examples 12-15 show the resulting
physical
properties of the adhesives made with a napthenic diluent. Steam was used to
cure all of
adhesives in these examples.
Table I shows the weight percent of each component used to make the adhesive
mixture for Examples 1-15, as well as certain test results from the foam
samples obtained.
CA 02440608 2003-09-04
WO 02/077083 PCT/US02/08753
14
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