Note: Descriptions are shown in the official language in which they were submitted.
- (~
~ D-9912-1
BACXGROUND OF TH~ INVENTION
A substantial amount of the materials used for carpet
underlay are formed from, what is termed, rebonded urethane
foam. Rebonded urethane foam is the product obtained when
small, shredded particles, e.g. ~ one-half inch cube in size,
of a flexibIe urethane foam are coated with a thin layer of a
prepolymer adhesive and compressed until the adhesive cures
` ~ sufficiently to maintain the particles of urethane foam i.n
the compressed state, i.e. - the product has dimensional
integrity or stability.
In manufacturing rebonded urethane foam, typically,
the shredded, small par~icle urethane foam is placed in a suitable
mixiny container, such as a ribbon blender, where the foam
particles are subjected to vigorous mixing. As the shredded
foam particles are being agitated, the prepolymer adhesive is
sprayed into the mixing chamber where it coats the particles of
scrap, flexible urethane foam. Water may also be added to the
mixing chamber before the prepolymer is added, at about the
same time the prepolymer is added, or after addition of the
prepolymer. The water may or may not contain a catalyst to
promote the curing of the prepolymer adhesive. After the
shredded foam and prepolymer mixture are thoroughly blended,
the mixture is transferred from the mixer to a mold and
compressed (if a batch process is being used) or to continuously
moving compression conveyors (when the process is "continuous").
In either case, the mixture is held in the compressed state
~until the shredded foam/prepolymer block achieves dimensional
., . .:
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D-9~12~1
,
stability. It is this compressed block of shredded`foam/
reacted prepolymer which is identified as "rebonded urethane
foam". This rebonded urethane foam may then be fabricated
into whatever shape is required for the particular intended
end use application~
Typically, the prepolymers which have been used ~or
such rebonded foam applications comprise the reaction product
of an isocyanate such as tolylene diisocyanate with a polyol
such as a polyoxypropylene polyol which may contain mi.nor
amounts of ethylene oxide on the order of about 15% or less.
,,:, . .
Prepolymers of this type suitably function to yield the desired
rebonded urethane foam product~ However, the economy of the -
manufacture of the rebonded foam product is dependent to a
significant extent upon the amount of the prepolymer adhesive
which must be used, the time needed to cure the prepolymer
;~ adhesive and the time before the rebonded polyurethane foam can
,I be "demolded" (i.e. - removed from the mold).
.! : ;I OBJECTS ~
,. ... .
l .. - ..... . .
It is an object of the present invention to provide
~; ,, .
¦ 20 novel prepolymer compositions which allow economies in the ~`
~' manufacture of rebonded urethane foam.
A further and more specific object provides prepolymer
; compositions which may be formed from tolylene diisocyanate ``
, re~idue blended with tolylene dii~ocyana~e,
l~ ~ A still further object lies in the provlsion of
prepolymer compositions which can be cured in relatively shor~ -
. ..
' periods of time.
,
~ ~ 3~
.. . .. .
' ' ' ' .-', :
D-9912-1
' '' :'
Yet another object of this invention is to provide
prepolymer compositions which allow rebonded urethane oam to
be made with relatively small amounts of the prepolymer
composition.
Still another object of the present: invention provides
prepolymer compositions that minimize the demolding time
required in the manufacture of rebonded urethane foam.
Another object of this invention is to provide
~ prepolymer compositions which exhibit improved stability upon
'10 storage.
A further object provides prepolymer compositions
which are h,omogeneous solutions which minimize processing
problems.
A stlll further object lies in the provision of
~ prepolymer compositions which allow the manufacture of lower
:! density rebonded urethane foams from a particular starting foam ~ ,,
~! source. , ", ""
Yet another object of this invention is to provide
novel rebonded urethane foams and a method of preparation '
~'20 thereof.
' , Other ob~ects and advantages of the present invention ~,'
~` will become apparent in the following description. '~,~
'. ',' '. ' . .
SUMMARY OF THE INVEWTION .
i ,~ In general, the present invention is predicated on
the discovery that prepolymer compositions exhibiting outstanding
properties for applications such as an adhesive for rebonding
., - : ~
polyurethane foams axe provided by the reaction product of an , ~,
~,~ ~4 ,'
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D-9912-1
isocyanate constituen~ consisting of tolylene diisocyanate
residueJ tolylene di~socyanate, diphenylmet~ane
diisocyanate, polymethylene poly(phenyleneisocyanate), and
blends thereof, with a polyoxyalkylerle polyol containing
between about 30 to 100 percent by weight of oxyethylene
and a free NC0 content in the range of from about 2 to
about 20 percent by weight, with the proviso that when the
oxyethylene content of the polyol is 100 percent by weight ~ :
the isocyanate is other than tolyIene diisocyanate or
diphenylmethane diisocyanate, Particularly useful and :
preferred prepvlymer compositions are formed when tolylene
diisocyanate residue blended with tolylene diisocyanate : ~:
is employed. The novel prepolymer compositions of this
invention, except when diphenylmethane diiocyanate is used, ; ~-
are homogeneous solutions. .
This invention further provides rebonded polyure- ~
thane foams utilizing certain prepolymer compositions ~:
as well as a method for forming such rebonded urethane :~
: - ~
foams. More particularly, this invention also provides a ~.
rebonded polyurethane foam comprising a block of foam -
. particles having dimensional stability and said particles .
being bonded together by a cured polyurethane prapolymer,
saîd prepolymer consîsting of the reaction product of (a)
an îsocyanate selected from the group consisting of .
.
:, :
~ 7 E;~3~
D-9912-1
tolylene diisocyanate, tolylene diisocyanate residue,
diphenylmethane diisocyanate, polymethylene poly(pheny-
leneisocyanates), and blends thereof and (b) a~.
.~; polyoxalkylene polyol having an oxyethylene content
. . . . .
of from about 30 to 100 percent by weight, said prepolymer
.; having a free NCO content prîor to curing, of from about .
',! 2 to 20 percent by weight. . .
.. ..
DETAILED DESCRIPTION ..
, . .
,
i The polyoxyalkylene polyol constituent should :~
~, contain a range of oxyethylene content which yie~ds a .. :
;, 10 homogeneous prepolymer solu~ion. By a homogeneous
~ . . . ...
~.............. prepolymer solutian, it is meant that, by visual inspee- ~ :
.. ~ tion, the prepolymer compositions are clear and solids .~. .
.l free or contain so little solid content that homogeneous
, solutions can be obtained by conventional filtration, as .:.
.l' will be hereinafter described. The homogeneity is .:
~ generally determined at ambient or room temperature
.~ conditions since, if:the prepolymer solution i:s not
homogeneous at such conditions, it will not be homogeneous
~ at~elevated temperatures, However, as will be pointed
1 20~ out hereinafter, when t~e prepolymer is a solid at ambient
. ~ :
: temperatures, it is suf~icient if the prepolymer is
: homogeneous at the temperatares at which it is a liquid.
~;-'. : In the manufacture of rebonded foam, it appears
.~ , . .
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D-9912-1
~L~`4~ 6
that the rate of prepolymer cure is directly proportional to
the oxyethylene content of the polyol utilized in preparing
the prepolymer composition. Thus, the higher the oxyethylene
content of the polyol, the faster the rate oE prepolymer cure
that has been o~served.
The range of the polyol oxyethylene content that can --
~; appropriately be utilized depends upon w~ether the prepolymer
composition is formed at room temperature or an elevated
temperature. When room or ambient temperatures are employed
~10 to form the prepolymer compositions of this invention, it has
been found desirable to maintain the oxyethylene content in
the range of from about 30 to about 80 per cent to provide
homogeneous prepolymer solutions. As the oxyethylene content
is decreased below 30 per cent, the prepolymers begin to lose
their homogeneous character after short storage periods. Indeed,
when polyols having oxyethylene contents of 20 per cent are used,
the prepolymers formed are non-homog~neous from the outset. In
high molecular weight polyether polyols, (e.g. ~ having hydroxyl
,
numbers in the range of 30-60), which may typically be used for
the manufacture of these prepolymer compositions for rebonded foam
applications, oxyethylene contents above about 70 per cent tend
to provide prepolymer compositions which are hazy or solid at
~, .
room temperature and have high freezing point values, making the
materials undesirable for storage and use in cold winter
, ~ .
temperatures. Accordingly, the preerred range of polyol
~oxyethylene content~or room temperature prepolymer preparation
lies in the range of rom about 40 to about 70 per cent.
:` :` :
.
~ 6-
~ . .
. .
i: , . '
,.. :'
D-9912-1
When elevated reaction temperatures are used in the
- preparation of the prepolymer compositions, the range of the
oxyethylene content of the polyol which will yield homogeneous
prepolymer solutions at the reaction temperature utilized lies
in the range of from about 30 to about 100 per cent. The
preferred range for elevated temperature preparation is from
about 40 to about 70 per cent, however, for the reasons discussed
herein in connection with room temperature prepared prepolymers.
Thus, polyoxyethylene polyols that are solid at room temperature
L0 may be utilized and will form homogeneous prepolymer solut:ions at
the elevated reaction temperatures employed. These are not
.
preferred since the resulting prepolymers will become solid~upon
storage at room temperature.
j The positioning of the oxyethylene units in the
polyol is not believed to be critical. Accordingly, the ~ -
polyoxyalkylene polyol can contain either internal ethylene
oxide or the polyol can be capped with the necessary ethylene
;~ oxide content.
The hydroxyl number of the polyol constituent can vary
Z0 within wide limits, depending upon the specific end use application
contemplated. Suitably, the hydroxyl number may ranse from about
25 or perhaps 20 to about 650. For most applications, including
rebonding urethane foams, it is preferred to maintain a hydroxyl
number range of from 30 to 60, and most preferably from 30-40.
As can be appreciated, lower hydroxyl numbers are preferred since
the amount of the isocyanate constLtuent needed for the prepolymer
will correspondingly be reduced, resulting in a more economical
operation.
, . ~ . :
; . ... .. . . ,. ~ . / . . ~
D-9912-1
.
The functionality and molecular weigh-t of the polyol
are not critical and may be selected so as to provide the polyol
with the desired hydroxyl number. With respect to the polyol
funckionality, diols and triols will be typi~ally employed but
functionalities up to six and even higher certainly may be used
if desired. With the hydroxyl number desired and the functionality
selected, tne needed molecular weight will, as is known, be set.
In rebonded foam applications, with typical hydroxyl numbers
desired, the polyols used will have molecular weights ranging ~rom
2,000 to 5,000, depending upon whether a diol or triol is involved.
The polyoxyalkylene polyol constituent may be prepared
using conventional procedures which, as is known, include reacting
either a mixture o an alkylene oxide such as propylene oxide and
ethylene oxide or sequentially feeding the subject oxides to a
hydroxyl containing starter in the presence of a catalyst, such
as potassium hydroxide. This crude product may then be refined ; ;
by any method, principally to remove the catalyst. Suitably, for
example, the crude polyol can be treated with magnesium silicate,
stabilized with 2,6-di-tert-butyl-4-methylphenol, filtered~ and
then stripped free of volatiles. For optimum prepolymer reaction
characteristics, is has been found desirable to maintain the
~` water content less than about 0.4 weight per cent, preferably
below about 0.1 weight per cent. Whi}e higher water contents in
;, .
the polyoI do not prevent the formation of a satisfactory
~` prepolymer, such higher water contents can result in the formation ;
; of a significant amount of carbon dioxide and urea which may cause ;
handling problems during the manufacture of the prepolymer
compositions. While propylene oxide is preferred for use in forming
. .
the polyol ~onstituent, other alkylene oxides such as butylene
.
~ -8- -
: ` ' `
, .,~ , . .
. .
'
D-9912-1
;~.O~L7~ Ei; -
oxide could be employed if desired.
The isocyanate constituent employed in forming the
novel prepolymers of this invention can range, in one embodiment,
from tolylene diisocyanate residue to pure tolylene diisocyanate.
As is known, tolylene diisocyanate is commerclally made by reacting
toluene and nitric acid to form the 2,4- ancL 2,6-dinitrotoluene
isomers, hydrogenating and then phosgenating, typically in a
solvent such as dichlorobenzene, to provide the conventional
mixture of 80 per cent 2,4-tolylene diisocyanate and 20 per cent
2,6-tolylene diisocyanate. After removal of the solvent, the
crude product undergoes a further evaporation in a still, with
the refined or puxe tolylene diisocyanate coming over. The
evaporatox tails remaining are black in color and extremely
viscous, even often solid, materials. It is the evaporator tail
material which is defined by the terminology used herein, as a
tolylene diisocyanate res~due.
If desired, and while not preferred, the tolylene
diisocyanate residue may be employed, as has been discussed, as the
isocyanate constituent for the novel prepolymers. When employed,
due to processing problems, it may be desirable to reduce the
viscosity by incorporating a suitable solvent such as methylene
chloride. The tolylene diisocyanate residue should be allowed to
age before usage by storage for an extended period of time,
e.g. - up to about one month or even longer. During this storage
period, as is known, some chemical rearrangement is believed to
occur; and the visc05ity initially increases rather significantly.
:, :
; Sufficient ~ging is achieved when the increment of the viscosity ;~
' increase begins to level off.
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.~ . . . .
(` (` \
it~47~ ~ ~ D-9912-1
The preferred isocyanate constituent is formed by
blending the aged tolylene diisocyanate resiclue with commercially
pure tolylene diisocyanate in varying amounts. Prepolymers formed
rom such blends provide both economy as wel] as outstanding
properties in rebonded foam applications as compared with pure
tolylene diisocyanate. Suitable blends are commercially available;
and, for purposes of forming the prepolymersv the amount of pure
tolylene diisocyanate used is not critical. While the weight per
cent of the tolylene diisocyanate in the blend can, of course, be
varied as desired, particularly useful blends are formed when the
tolylene diisocyanate used is from about 33 to 67 weight per cent.
As should be appreciated, somewhat differing results are
achieved depending upon the character of the tolylene diisocyanate
residue used. It is preferred to employ residues that are
homogeneous in character, as visually evidenced by the lack of
solids present. Residues containing some solids can be used but
result i~ prepolymiers which retain these solids. Homogeneous
prepolymer solutions can, however, sometimes be provided by
; flltering the resulting prepolymers; and the solids content of
such prepolymers should be distinguished from the extent of solids
in prepolymers formed from residues and polyols not within the scope
of this invention which cannot be easily and economically filtered
to provide homogeneous prepolymer solutions. ,Thus, as is known, -
it is ccnventional in connercial operations to employ filters such
. : .
as, for example, cone filters. To be useful in such applications,
the prepolymers should plug or foul the filters. Whether
appropriate fil~ration can provide a satisfactorily homogeneous
!
~olution can ~e determined by using a conventional laboratory p
filter. If the prepolymer containing solids can be processed through
;
- 1 0 -
.'., . , :':
':
1~47~i86 D--9 912--1
such a pressure filter to remove the solids, the resulting
prepolymer can be considered to be within the present invention.
In addition, the isocyanate constituent may also be
diphenylmethane diisocyanate (MDI) or poly~phlenyleneisocyanates~
(polymeric MDI). When polymeric MDI is utilized, the resulting
prepolymer is not homogeneous. Conventional filtration of the
polymeric MDI before the prepolymer is made (i.e. - pre-filtration)
allows preparation of a prepolymer which, when first prepared, is
essentially free of solids; but solids or sediment develop upon
~10 standing at room temperature. If, however, the prepolymer is
filtered after being made (i.e. - post-filtration) the filtered
prepolymer remains a clear, black homogeneous liquid, even when
stored at room temperature for three weeks. Accordingly, when
polymeric MDI is employed, at least a post-filtration should
desirably be employed. However, the other isocyana~e constituents
are generally preferred in relation to polymeric MDI due to the
superior performance in rebonding polyurethane foams.
MDI may also be suitably employed as the isocyana~e
constituent and is unique in that a homogeneous prepolymer solution
20 does not result, regardless of whether filtration is employed.
The character of MDI-prepolymers remains essentially the same
; regardless of the oxyethylene content, i.e. - a white slush
which is relatively stable insofar as phase separation is concerned.
MDI prepolymers made with polyols having oxyethylene contents less
' than 30% are not preferred, however, since such prepolymers are
3 --
relatively inferior when employed (as an adhesive for rebonding foams)
Because of the lack of homogeneity of MDI prepolymers, their use
is not preferred in applications where fouling of rebonding
~ , .
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.
- . .. .
~ D-9912-l
apparatus can readily occur, e.g. - in apparatus which includes
filtering means. However, in applications where fouling will no~
present a problem, MDI prepolymers can be employed and possess
outstanding utility for rebonding polyurethane foams.
Blends of any of the isocyanate constituents may also
be employed if desired. In addition to blends of tolylene
diisocyanate and tolylene diisocyanate residue, particularly
useful blends include blends of tolylene diisocyanate and
,, .
polymeric MDI with tolylene diisocyanate contents of from 40 to 60
weight per cent, based upon the total weight of the blend. As
will be apparent from the prior discussion, depending upon the blend
utilized, filtration may be desirable to provide homogeneity for
the resulting prepolymer or use may preferably be restricted to
non-fouling applications when significant amounts of MDI are employed.,
To form the prepolymer compositions of the present
invention, the polyol and isocyanate constituents can be mixed -
together in a reaction vessel at either room or el vated
temperatures, and with or without a catalyst. Suitably, for example,
when elevated temperatures are employed, the isocyanate constituent
can be charged to the reaction vessel and heated; and the polyol
; may then be thereafter ~ed at a rate to maintain the desired
reaction temperature. Suitable catalysts include any of the many
known catalysts for catalyzing isocyanate-polyol reactions such
as organotin compounds such as dialkyltin salts of carboxylic
acids, e.g. - dibutyltin diacetate, dibutyltin dilaurate,
dibutyltin maleate, dilauryltin diacetate, dioctyltin diacetate,
.. ` , . ~ .
and the like. Stannous octoate and the like and tertlary amines
such as bistdimethylaminoethyl)ether are further suitable
~ representative examples. Typically, the catalyst may suitably
.' :
-12-. .
'; " '
`' ... ,, . ~ ~. '
D-9912-1
be employed in small amounts, for example, from about 0.0001
per cent to about 5 per cent based upon the weight of the
reaction mixture, most typically O.OQl to 0.020. If a catalyst
is to be used, it may be blended with the polyol or alternatively,
added to the reaction mixture in the reaction vessel. After all
the constituents are completely mixed, the reaction is allowed
to proceed until the generation of prepolymer is complete, as
is evidenced by the visual prepolymer ~larity or stabilized
viscosity or free isocyanate ~NCO) content characteristics.
At room temperatures, the reaction time may vary from about
3 days when no catalyst is employed to about 1 day when a
catalyst is employed. At elevated reaction temperatures,
e.g. - 50C., the prepolymer generation reaction will
typically be complete in less than about 5 hours when no catalyst
is present. As will be appreciated, elevated temperature should -~
be employed when the polyol constituent is normally solid at - ;~
ambient temperatures. Also, when ambient or room temperatures
:,
are used, it is necessary to utilize intimate or vigorous mixing,
such as can be achieved by conventional mixing apparatus providing
high shear.
With respect to the relative amounts of the polyol
and isocyanate constituents, the ratio employed should, from
. ' i . .
the functional standpoint, provide a prepolymer with the lowest
; ~ ree NCO content that will perform satisfactorily in the
. ~ . .
-~ intended end use application. Typically, the free NCO content
., .
l can suitably vary from about 2 to about 20 per cent. As the
;l free NCO content of the prepolymer~ of this invention is
` decreased to approach the minimum, the prepolymers tend to.
; become unstable, as evidenced by significant viscosity increases
.
~ .
~ -13-
,
1 .
. ~ . . . ~ . . ..
D-9912-1 ~
7~
in storage. Prepolymers employing free NCO contents
approaching the upper limit of the range tend to allow
formation of undesirable lower molecular weight compounds
such as ureas which adversely affects the adhesive
properties of the prepolymers. Most preferably, when the
prepoiymer co~position is to be used for rebonding urethane
foam, the free NCO content will be in the range of from about
;~ 5 to 10 per cent. The optimum content tha~ has been observed
L for this application is about 10 per cent because of the faster
curing times achieved in comparison to prepolymers containing
lower free NCO content. While higher free NCO content
prepolymers than those set forth herein can perhaps suitably be
; used, it should be appreciated that this is generally
undesirable due to the loss of more free isocyanate into the
atmosphere.
If desired, a diluent may be added ~o the prepolymer - -
in amounts necessary to reduce the viscosity to whatever level
is required. Any diluent may be utilized so long as, of course,
no significant adverse effects are caused in the particular end
~20 use application. As an illustrative example, methylene chloride
has been found to be a satisfactory diluent.
In forming the novel rebonded urethane foams of this
i~vention, the process described hereinbefore may be utilized.
Thus, the polyurethane foam, generally scrap, is comminuted or
shredded into relatively small particles in conventional
apparatus`such as a grinder. The particle size of ~he shredded
foam is not critical and will vary depending upon the type of
,
` grinding used. Uniformity of particle size is not needed, and
a typical shredded foam may contain particles smaller than 1/16
i
: ~ .
~ 14 ~- -
:.
D-9912-1
of an inch or smaller up to particles having at least one
dimension perhaps 2 inches or more. The shredded foam may
also contain in commercial practice minor amounts of a wide
variety of other scrap materials ranging from, for example,
string to polyethylene film.
The shredded foam is then transported to a mixing
container such as a ribbon blender; and, while the foam
particles are being agitated, the prepolymer is added, typically
by spraying. Water is typlcally added to the mixing container
before addition of prepolymer, at the same time, or after.
After thorough blending of the shredded foam and
prepolymer is achieved, the mixture is transferred to a means
for compressing the foam to provide the desired product,
thickness and density. In the case of a batch process, the
mixture is transferred to a mold; and, in the case of a continuous
: process r the mixture is fed into continuously moving compression
conveyors. In the case of a continuous process, the mixture may
first be transferred to a second ribbon blender to insure that
adequate blending is obtained.
The shredded foam/prepolymer blend is held in the
compressed state, as is well known in the rebonding art, until
; dimensional stability is achieved, i.e. - there is little or
no tendency for the compressed product to expand. More -
par~icularly, and as is known in this field, the lack of tendency
for the compressed~product to expand is a relative term. The
term dimensional stabLlity refers to the stability provided by
curing the rebonded foa~ as is conven~ionally carried out in this
.
field, and the slight expansion which may occur is to be
contrasted to the significant expansion tendencies when jns~;ci~n~
curing is used. Curing of the blend can be carried out at either
~ `, ' '' '' ' ' .
-15-
.
.~ . . ~ .... . .
D-9912 1
~l7~
room temperature or at elevated temperatures by injecting hot
fluids such as steam or hot dry air or by subjecting the
compression container to a conventional radiant heat source.
; With room temperature curing, it may be desirable to use minor
amounts of a catalyst. Suitable catalysts and amounts have been
described in connection with the formation of the prepolymers.
The resulting block can then be further fabricated as
desired.
, The utilization of the prepolymers of the present
L0 invention present no processing problems, achieve faster curing
times, require lesser amounts of -the prepolymer adhesive and allow
shorter demolding times in comparison to the presently used
prepolymers.
The resulting rebonded polyurethane product can be
characterized as a dimensionally stable block of varying size
depending upon the intended application. The block comprises ~ ;
discrete foam particles bonded together by an amount of cured
prepolymer sufficient to provide the block with dimensional
stability. While larger amounts can be used, it will generally
be suitable to use no more than about 4 to 6% of prepolymer,
based upon the total weight of the block constituents and
including the prepolymer. This is in contrast to the ~ to 12%
often used with the prepolymers in present practice.
I For a given product density, the rebonded foam products
of this invention exhibit tensile strengths, tear strength and
compression load deflections comparable to products using
conventional prepolymers. An added advantage of the present
invention, however, resides in the ability to make useful lower
density products from shredded foam of a partlcular density than
, ~,
- -16-
~7 ~ D-991~
~.
can be achieved using conventional prepolymers. As an example,
with a foam source of 1.5 lbs.tft.3, rebonded foam products
having a density of about 2.6 lbs./ft3 acc:ording to the present
invention can be achieved in contrast to foams using conventional
prepolymers that generally result in foam densities no lower
than 3 lbs./ft.3, typically 3.5.
The prepolymer compositions of the present invention
and the use of such compositions in forming rebonded urethane
foams may be further illustrated by means of the following
examples. It should be understood, however, that these
examples are intended to be merely illustrative, but not in
. .
; limitation of, the scope of this invention. ~
, .
DEFINITIQNS
As used in the Examples appearing hereinafter, the
following symbols, terms and abbreviations have the indicated
meanings:
::
"Cookoutl' denotes the period a reaction mixture is -
heated after all starting materials have been added. ~;
"Ionol" denotes 2,6-di-tert-butyl-4-methylphenol.
"Max." denotes maximum.
"Stripped" denotes removal of volatile materials by
heating at reduced pressure.
"Crude hydroxyl number" denotes the hydroxyl number
of the stripped, unrefined polyol, corrected for alkalinity.
"Mixed" ~ln relati~on to type of feed) denotes that
!
that alkylene oxides used are mixed prior to introduction into
the reaction vessel.
"SequentiaI" (in relation to type of feed) denotes that
the alkylene oxides used are introduced into the reaction vessel
in discrete units.
-
-17-
.~
- D-9912-1
"Psig" denotes pounds per square inch gauge pressure.
"Wt." denotes weight.
"Ion Exchanye" (in relation to refining) denotes
removal of the catalyst from the crude polyol by employing
appropriate ion exchange resins.
"Gm" denotes grams.
- "Cks." d~notes viscosity in centistokes at 25C.
"NCO" or "free NCO" denotes the free isocyanate content
~ in weight per cent.
! "Not homogeneous" denotes a prepolymer containing visible
solids.
"Homogeneous" denotes a clear prepolymer solution ~ree
of visiblé solids.
.
, PREPARATION PROCEDURES
.
The polyols, prepolymer compositions and the laboratory
formed rebonded polyurethane foams described in the Examples
presented hereinafter were prepared according to the following
procedures:
A. Polyols ~
.. . - . .
Because of reactor geometry, when the procedure
indicates multiple steps were used, the indicated amount of the
crude polyol product from the particular step was used as the
starter for the following step.
B. Prepolymer Composition ~
At room temperature, the procedure involved consisted
of weighing the isocyanate constituent into a reaction bottle,
;l : ..
weighing the polyol constituent containing 0.03 parts stannous
octoate per 100 parts polyol into the reaction bottle with the
`' isocyanate and mixing the isocyanate and polyol by vigorously
:' ' i. :~.'
-18-
.;
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1~4~i86 D-9gl2-l
shaking the reaction bottle at ambient temperature. The
reaction blend is then allowed to react without further
agitation. After all the ingredients are completely mixed,
the reaction mixture is allowed to react until the generation
of the prepolvmer is complete, as visually evidenced by
prepolymer clarity. The followi~g Examples were made by this
room temperature technique~ 12, 15-24, 39, 41 and 43.
Examples 13 and 14 were formed using the same procedure except
that the reaction mixture was maintained at 60C. Examples 39,
`1~ 41 and 43 were agitated during their preparation.
ALl other prepolymer compositions were formed by
the following procedure:
The isocyanate was charged to the agitated rèaction
flask and heated to 65C. under an inert atmosphere. The
polyol was fed to the isocyanate at a rate to keep the temperature
between 65 and 70C. After all the polyol has been fed, the
temperature is increased to a cookout temperature of 80C.
Analyses of the prepolymer free NCO content and viscosity were
performed at various intervals, and the reaction was considered
complete when the free NCO content and viscosity became stabilized.
C. Laborator~ Rebonded Urethane ~oam Preparation
One hundred forty-~hree grams of shredded, flexible
urethane oam are weighed using a Mettler balance (Type K7T,
maximum capacity 800 grams); and the weighted foam is then
poured into a five-gallon open top bucket. While stirring the
shredded foam in the~bucket, 15 cubic centimeters of water are
slowly added to the shredded foam. Fifteen grams of prepolymer,
aged for at least 24 hours after formation, are placed in a 20 - ~
- . ' . ' ~ .
;, -19-' ,~
;:
, , , . . . : .,. - - . - . , . ., -: :
D-9912-1
47~
cubic centimeter hypodermic syringe. While vigorously stirring
the shredded foam/water mixture by handj the 15 gxams of
prepolymer from the syringe are slowly sprayed into the shredded
foam/water mixture. The vigoxous stirring of the shredded foam/
water/prepolymer mixture is continued for 30 seconds after
addition of the prepolymer to the foam/water mix. A 10 inch
high metal cylinder, having an 8 inch inside d1ameter perforated
with 3/32 inch holes in the lower 2-inches of the cylinder, is
placed on a metal plate, approximately 1/2 inch in thickness,
20 inches long and 20 inches wide, with the perforated cylinder
end down. The perforations are in two rows with one row being `
1/2 inch from the bottom of the cylinder and the other row 1-1/2
inches rom the bo~tom of the cylinder, the holes being spaced
1 inch apart both horizontally and vertically. The shredded
foam/water/prepolymer blend is then poured into the cylinder. A
solid wooden cylinder (7-3/4 inch diameter by 2 inches high)
, ,
with three metal nails extending 2 inches from one end of the
wooden cylinder is placed on top of the foam/water/prepolymer
mixture with the metal nails extending downward into the foam.
Four 5-pound lead weights approximately 3 inches in diameter
are then placed on top of the wooden cylinder, forcing the
wooden cylinder down into the metal cylinder until the nails are
solidly in contact with the metal plate under thè cylinder. The
~ ...................................................................... . .
metal plate with the metal cylinder, wooden cylinder, lead weights,
an~ compressed foam mixture is then placed in a circulating,
forced air oven which is preheated and preset to maintain a
constant temperature of 150C. The entire assembly is kept in
the hot air oven for 15 minutes, or other cure time deemed 1~Si~Q~I9 ~ `
to determine differences in the prepolymer reaction rates. At the
'.'
.'~
.^. ' '"' ~:`-
~4768~ D-9912-1
,
end of the cure time, the block of rebonded urethane oam is
xemoved from the cylinder and subjectively evaluated to determine
the relative degree of cure of the prepolymer composition.
STARTING MATERIALS
,
In the Examples appearlng hereinafter, the following
designations are used to denote the indicated starting materials:
A. Polyols
"PEG 4000~' denotes a commercial:Ly available l'Carbowax"
polyethylene glycol having a number average molecular weight in
the range from 3000 to 3700.
"PEG 1000" denotes a commercially available "Carbowax"
polyethylene glycol having a number average molecular weight in
the range of from about 950 to about 1050. .~ .
"PPG" 425" denotes a polyoxypropylene glycol having an
' average hydroxyl number of 265. .~ .
:~ B. Isocyanates
; "TDI" and "TDI-P" denote a mixture of 80 per cent
2,4-tolylene diisocyanate and~20 per cent 2,6-tolylene diisocyanate.
; "TDR" denotes a commercially available product conslsting ~:
of a blend of TDI and residue, the product having an average free
NCO content of 39.6%. . ~
C. Catalysts : . :
"Polycat 12" denotes a commercially available
dicyclohexylmethylamine catalyst. .::
.
,
, POLYOL PROPERTIES .:
A. Hydroxyl Number
~ The hydroxyl number of a polyol is the nu~er of
milligrams o potassium hydroxide required for the complete
~ .'
..
. -21-
,:
., .
~ ~ 4 ~ ~5 D-9912-1
hydrolysis of the fully acylated derivative prepared
from 1 gram of polyol~ The hydroxyl number can also
be defined by the equation: OH - 56.1 x lOOO x f where:
m.w.
OH is the hydroxyl number of the polyol, f is the
functionality, that is, average number of hydroxvl groups
per molecule of polyol and m.w. is the molecular weight
, .. ., .. - -.
of the polyol.
C. Oxyethylene Content
Measured by either Nuclear Magnetic Resonance -
("~MR") or calculated from the ratios of the alkylene
oxides used.
D. Oxypropylene Content
. . .
~` Calculated as the difference from 100% in view
of the polyol oxyethylene content.
PREPOLYMER PROPERTIES
Free NCO Content
,i ~ .
.`~'! ASTM D1638.
FILTRATION :
In all instances, the filtering of the isocyanate
.. . . . .
reactant or the resulting prepolymer was carried out by
emplo~ring a conventional l-liter, stainless steel pressure
filter. A coarse grade commercial filter paper was used,
and pressure application was achieved by nitrogen at 90
, psig.
'~'1 . . .
`¦ EXAMPLES 1 TO 7
.~ Examples 1 through 7 illustrate the preparation,
~-l using a mixed oxide feed, of polyoxalkylene polyols having
~, oxyethylene contents varying from 20 to 100 per cent.
The details of the preparation and the analyses of
the crude and refined products are set forth in Table I:
-22-
.~,
~7~8~i
D
_I ~
~t N C) ~ O ; .
U7 ' ~ . O
CO rl O CJ~ ~ O
'X
O ~ O ~ ~
~ ~ ~' X ~O ~ U~ ~ .
i ~ ~ oC~ ~ I rl O ~ O ~
I tn u~ O u~ ~ O O
'~ ~ O
. ~ O ` ~ ~ `
C ~ O C~ 1 0 ~
;~ ~~ 0
~ O
.~ ~ 1~
_~ o ~ ~ ~ ' I I I O C~
.C U~ :
~:` 3 ~ ~:
a) 3
O ~ ' ~ ~ ~ -I O . . , :
o o ~--~ ~ `
U l U~ ~ I X ~ 0~ I -- ~ O O t~ r C~
~ h '` ~: U
P~ U~
. P U ~ ~ C
o ~ C r
~ _, c~ c~ e O , :
~' ~o ~
. ~ V g~ COO U~ o) p ~
., u p~ ~ o ,~ ~ e ~ :
e ~ ~ r
o 3 ~ x
~ ~ ~ a, o ~ ~
a~ ~ ~ v ~ ~ JJ v v ~
O OD ~ 1 c~ e ~:
~1 ) S~i Xo Xi ri S ~ X~ ii i
v v ~ v o ~ ~ r , . . 'v ~ .r e ~ r i D
~ .- _ û 'n ~ o ~ ~ .r. ~ a .~ .r. . ~ V ~ ~ O ~ ~
X u ~ r~~ ~ ~ 2 C~ O ~ i r-i ~ ~ 3 ~ i ~ V
s~ iJ~ i3~
:
~t~6
~rl x
x ~ o
o ~
o
g
o~ ~ o
g
~1 ~ o _I o ~o oo
X ~ a~ o ~
^~o
~: o o
,
, H
'~' ' ~ ~ O
a~ o P~ o x ~ e~
,~ o o r I o ~ . O t.- .
,~: ~ : .'
v~ ~ ~ XCJ~ 1 O .11 ~. O ~
~ ~ ~ , x æ ~ r~ z O ~ ~ ~ ~ ~
,. ~ P~
~ _~
~0 ~ r~
a~ la ~ a
¦~ ~n .~ ~ ~ r o ~ ~ oO
X r o
~r ~ ' :~
t: ~` .''~
a "
V ~ _ ~ ~ O ~ r~ ~ r ~ C . ~ .
o ~ I ,~ ~ n ~ r
u 0 ~ e ~ 0 ~ e c
v~ 5~sae~0~0~
,; ; .,
: ; ~
, .
D-9912-1
47~
EXAMPLES 8 To 10
Examples 8 to 10 illustrate the preparation of
three polyols using sequential feed and having oxyethylene
: contents within the range used to form the prepolymer
compositions of the present invention.
The preparation details and the analyses of the
. crude and refined polyols are set forth in Table II:
.. . ' , ". . '. '~ .
' , ' ' . ', ~' .
' , ' ' -
', , . "
.. .. ..
'~1 : ~ . ,. ,, ;,
. . ,
~. ~ :: :: - : :
, ~: : , :
:., ~ : l:. .
` ~' . . ;
.
,, , , .:
.~ .,
;,
~: .
D-9912-1
TABLE II
Se~uentail Oxide Polyol Preparation
Example No. 8 9 10
Starter Data
Starter PPG 425 Special Special
Starter(b) Starter(d)
Weight, grams 542 580 633
Potassium hydroxide, gram5 5.5 5 6
Feed Data
- Ratio of ethylene oxide/
; propylene oxide 40/60 38/62 41/59
Propylene oxide, grams 6~3 610 660
Ethylene oxide, grams 874 398 926
Propylene oxide, grams 693 610 669
Ethylene oxide, grams 882 398 926
Propylene oxide, grams 693 610 660
Temperature, C. 114 114 114
Pressure, psig 60 60 60
Feed time, hours 4 3.5 5
Cookout time, hours 2.75 3.25 2.75
Crude hydroxyl number 37.5 40.51(c) 38.70
Refining (a) (b) (c)
Analysis of Refined Product
Hydroxyl number 37.0 37.01 37.8
;~ Acid number - 0.005
Water, per cent 0.026 0.026 0.36
`~ Total alkalinity - 0.00007 -
.
~:
.
______
(a) Refined by treating with 2 per cent by weight magnesium
silicate, stabilized with 500 ppm Ionol~ filtered and stripped.
(b) Special starter made by reacting 76.1 grams of propylene
glycol with 533 grams of ethylene oxide.
(c) Adjusted hydroxyl number by feeding an additional 248
grams of propylene oxide.
:. , ,
~d) Special starter made by reacting 758 grams of a product
formed ~y reacting 3 moles of propylene oxide with one mole
of glycerine in the p~esence of KOH catalyst with 1246 grams
of propylene oxide.
. I :
-25- -
~Q ~~C~
: . .
.:, : ...
.
~ ~:
~7~ D-9912-1
. EXAMPLES 11 TO 24
Examples 11 to 24 show the preparation of prepolymer
compositions using polyols having oxyethy].ene contents ranging
from 14 to 100 per cent and TDR, with the exception of
Examples 16 and 17 which used TDI.
The prepolymer compositions prepared were evaluated
from the standpoint of appearance and were then twith the
~- exception of Examples 23 and 24~ used~to form laboratory rebonded
urethane foams as has been described herein.
The results are set forth in Table III:
..
' : . . ' ' '
;: , .:
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.
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. ' ,~ '.
26- .
' ! ~ ,
: ' .. .
- l :
76~36
o~ ta o ~ ~ ~d ~ rd u~
.,,~ ~ o o 4~ o ,~
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rC a~ O '~:1 U
~0~ ul a)h ~ 1~ ~ O Cl J-
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O ~ JJ O ~ ~ O
OO ~ r-lo o ~ o r~ 00 h ~ u ) p~ U C~
~ r~D ~D ~ Fi ~ O ~ O D ::~ O ~ ~ O
o~ ~rd O ~~ D O r~ ~ JJ r~ 1 O O LO
r--l r~r~ a r~ r~ U ~ r-~
v ~ O a~ n O ~
o~ ~~ r,~ ~~ O ~ 0 1~ ~ D ~ rl V U ~ D o O ~rl rl
F~ ~~ O JJ~ d D ~ O v ~.J O UO ,~
r-l ~r~ D ~r~ 'O JJ ~ D S~ D r-l u~
C~ Y ~ e ~
a~ ~ ~ O O O C~ ~ U ~ O ~ ~ a\ O O ~
11 0X O ~X O ~1) ? O r l u) O _l rl X O LO O O ~ ~ O r-l rl
p~ D~ ~u r~D rrl O C~ D r~ O ~ ~ E3
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Q~ i~s~ h ~ 3 _sO --I :1 ~SO
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S-~~ O~ ~O~ S ~ S ~'S ~ 0 Q~
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o ~ ~ ~ ~ ~ v v JJ r~ E ~, ,~, r, h
~L ~rs ~ ~rS 3 ~rl 5~; V ~s ~rS e V ~ ,,, j2 ~r~S 0 ~rs 0 ' '
O,s r-lO r~S O r-l O r-!S O r-s o r-s O ~.~ O r I Os r-l s?i
~LS O O s ~ D U~ X D ~n O rt~ O
SS'~s '~'
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. r ~O ~D 1~ 1~ ~ ~O
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,
686
~ ~,
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a)~a ~ o ~ ~ e~ u_
s~ ~ 0 ~ ~ e o a)
t~ D rl tU ~ ~ ~ ~ 1-1 tU tU
au
,~ g U a o ~ o~ g ~ ~ a
~) ~n C ~ 1 ~ o ~ D~ C IU Q~
o a~ ^ ~: ~,1 c ~ c ~n u~
~ ~ .J e ~ o u c ~ o o r~ P E ~ c ~ e
a) C O o ~ D e ~ ta JJ a) o O ~ ~
o O ~ U~ t t ~ ~ . h ta ~c ~ u a ~o ~ Z Z
tu tu
tc~ u e ~ u u 8 ~
tt~ ~ tU ~~ C f~ ~ D ~0
n ~a ,D ~ ~a V ~ ~ V r~
¢ ~ ~ tn tU ~ tu ~ tl~ ~ tl~ 1~ 0 C tt) tU o ~ tn
~ o o ~u o ~u o ~u o ~u o o ~u ~u o
~ u~ c ~ ~ 4 v ~
~ ~r~ c ~ o~ o~ o ~ o ~ rl c
P ~ ta t~tu tu o ~ ~ ra
O O ~c) 1~ ~ C ~n ~ tU r
~ P~ ta U ~rl 3 ~ rl ~ C O ,1 P~ C ~a
C~ ~ X ~U ~U ~ O~ Or~ O,~ 0 ~1 ~U U ~ U ~U
~ ~ e u ~ v~ D u~ D cn ~ ~
n p.~ 'U
~0 u~
. I :Z OO O
1~ O ,~ r~~O `D ~O ~O r~ :
O ~L ~U ~
,~ ~U ~U
~a P~ ~ ~ :
Vlu ~ o
O p~ H _I ~ _I ~ _I ,1 ~ ;~
~L 0
., ~ ~ . '
~U
~O O ~o O GOo
0~
1~ ~ C
O ~:L ~ ~U ':'
~J ~ ~
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~ ,~ ~
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.. ~ ~ ~U ~U
r~ , 0~ j.,,."~,:
: ............. P~ ~ ~a C
o
æl ~ ~ ~~ 'N ~ '') `t
'~
:
~7~ D-9912-1
' :
As can be seen, by maintaining the oxyethylene ~ :
co~nt of the polyol within the range of from 30.to 100 per
- cent, the laboratory rebonded foam blocks formed from the
prepolymers usin~ such polyols can be satisfactorily cured
~: in 15 minutes.
EXAMPLES 25 TO 29
These Examples illustra~e the effect on the
homogeneity of the prepolymer composition due to varying the
oxyethylene content in the polyol constituent.
The various prepolymer compositions were maintained
at a cookout temperature of about 80C., and analyses of the
free NCO content, viscosity and visual appearance of the
prepolymers were made after cookout times of 1, 3 and 5 hours
as well as after varying days of storage at room temperature.
~ ~he results are set forth in Table IV:
', ' ' :
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. ~ ` ''
. ' ' . "~
.
,. .. .
~L0~761~ :
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b~ ~ bq bl)
o o o o
o S S s S
N ~ D 0~1 1 1 ~ 0 I I ~ u) I I
O O O O
N 0 E b~ N 0 ~ o
0 ~1 u~ O O d' o ~ O
N ~ S 0~1 ~I,I S 0~I~I S Lf) I I S
. ' ' .
~ tg u~ u~
::~ o ~ O
: i O O o a~
" ~ 0 b~ o ~0Q b~ bo
~, ~1 ~-- ~ILt) ~ Ln ~o N N o ~ ~:) o o
O N [' ~ ~1 ~ DS 0 ~t ~1 ~1,~ 0 ~1 ~I S L~
O
~' ~0 o O
. ~ o ~ ~ E o ~ E
N ~S) ~ ~I N ~D S 0 r-l t--I ~I S 0~1 ~I S Ir.t ~1 'I S : ;
O
'" 1 ~ o O O '~ ~' '' ` '
; ~ 0~ :
o ~ 0 S S o ,
) N ~ ~O ~1 ~1 U:) ~ 0 ~ I I C ~'7 1 I C ~ I I ~ -
~ ~:
'.. I S ,; ~
X ~ 0~
U ~ X~ a ~ O E
o(~ S ~ s ~ s
- ~ :~ V ~ ~ ~ ~ V ^~ >, t .:
E E rl ~ E r~ o
Z ~ o ~ +, a) ~ o ~ ~ O h O
tQ b~ ~ O ~ aQ~ ~$t~ $'t ~o o~ td Z ~ ~ ~O (~) Z '~ t ~ $ `
S ~ o E~ Q, o Oo ~ o ~ O ~ o ; :~
V E~ ¢ V V -~ V
29 - ~
~~. `,:: : : '
- ~0~76~36
a)
bq tH
o o o
o ,~
o o .
C
o
,~ o ~ X
",
~, ~ ~ ~ .
o
~
~ ~ ~ e ~ ~
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O . .
~ ~ '`, X ~ ~ :
~ .
"J~ U
1 ~ ~,' N
oo ~ z ~
- 29 a~-
',',', ' ~ :
. .~ -
( ~
~ 7~ ~ ~ D-9912-1
In contrast to the prepolymers formed rom polyols
having oxyethylene contents of 14% (Ex. 29) and 20~ (Ex. 25),
the prepolymers formed from polyols having oxyethylene
contents in the range of 30 to 50% exhibit homogeneity upon
formation and have stability which allows storage at room
temperature for a number of days without losing the homogeneous
characteristic.
~ EXAMPLES 30 TO 33 :~
- Examples 30 to 33 illustrate the effect of varying
the amount of free NCO content of prepolymers formed from TDR. ~:
and a polyoxyalkylene glycol having an oxyethylene content of
43 per cent and which is described in Ex. 6. .
i The ree NCO content was varied from 3 to 10 per :
cent, and a cookout temperature of 80C. was used. After periods
of 1, 3 and 5 hours as well as after storage for a number of
days at room temperature, analyses of the NCO content and the
viscosity were measured.
The results are set forth in Table V: :
.. , , ~.
'.~ . . , ;.~ .
., ` ! ~ : " ' '
'. l '', " '
' `' . j
.
~;~"' . ' ' ''' .' '
. ~1 ' '.
', , '., ',
~: :' '.
~: ' .' ' ',.
-30- .. ...
".
D-9912-1
Ln O ~ ~ ~ 'I 0
O n n co ~-~ ,~ Ln ,
,_~
rl ~ .,
~} ~ d' N ~ C~
Ln ~ L o ,~ ~_ "~ n r~
. ~ ~ ' ' :5
o~ t~
. p ~ . , .:
8 ~
ai ~~ I o ~ ~3 ~I tr) ~ O t~
. r ~ C~
'~ : ' : ' ' '~' ~ . ~ ,': '
~ . . .
~ f ' ' ~: ' , .'
: ~ L U~ h Ln
O h ~ O h ~ O $ ~ ~ -
: o ~- ~:o ~ h ~ R ~ ~ ~ ~ U
f' l~ ' X ~ ~ ga
~! . 3 1 ~ ~ `
, .. . .
D-9912-l
61~
As can be seen, the viscosity of the prepolymer
~decreases in a linear fashion with increasing free NCO
content. However, upon storage, the prepolymer having 3% free
NCO content are less stable.
EXAMPLES 34 TO 37
These Examples compare t~e properties of prepolymers
: made from both TDI-P and TDR and with a conventional poly-
oxypropylene triol containing 14 per cent ethylene oxicle and
having a hydroxyl number of 46 to prepolymers made with the
polyol of Example 6 (oxyethylene content of about 43 per cent).
~ cookout temperature of 80C. was maintained in all
: instances, and analyses of various samples-at certain times of .
cookout were made for the NCO content, the viscosity and the :::~
. -.
appearance of the prepolymer~ ~.
The results are set forth in Table IV: ;
:: . .
, .
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b~21 hrs. ~:
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~ 4~ D-9912-1
The prepolymers of Examples 34 and 37 exhibit
superior stability in contrast to the prepolymers of Examples
35 and 36, which were made with a polyol having a low
oxyethylene content.
EXAMPLES 38 TO 43
Examples 38 to 43 illustrate the effect of reaction
temperature and polyol water content on the reaction rate
of prepolymers formed from TDR and the polyol constituent
prepared in Example 6. The-water content of the polyol of
Example 6 was increased for Examples 40 and 41 by water
addition. The water content for Examples 42 and 43 was
decreased by stripping.
A cookout temperature of 80C. was compared with a
temperature of 25-30~C., and analyses were periodically made
of the viscosity and the free NCO content. After storage
at room temperature for a number of daysl the prepolymers
were also evaluated vlsually for appea~ance. The results are
set forth in Table VII~
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D-9912-1
Prepolymer reaction rates are much faster at
elevated temperatures, as evidenced by the free NCO content
and viscosity characteristics. Increased water contents
result in increased viscosity in the resultant prepolymer.
As can be seen from a comparison of the prepolymer of Example
43 (low water content) with the prepolymers of Examples 39 and
; 41, a room temperature, uncatalyzed reaction requires a
minimum water content to provide a homogeneous prepolymer.
EXAMPLES 44 TO 46
Prepolymer compositions according to the present
invention were compared to a conventionally used prepolymer
composition in the formation of low density rebonded oam by
batch technigues.
The prepolymer compositions evaluated are set forth
in Table VIII below:
. - .: .
TABLE VIII
Prepolymer Compositions - Batch Trial
E ample No. 44 45 46
Polyol, oxyethylene content~ % 14(b) 43(a) 43(a)
~20 Isocyanate TDI TDR TDR
NCO content, % 10.0 6.5 10.0
.~ . .~ .
~a) The polyol of Example 6.
(b) Sequential feed, KOH catalyzed polyol formed using a
~- glycerol starter.
In the control run, Example 44, 33 pounds of prepolymer
per pound of Polycat 12 catalyst was used. The buns could be
demolded after one hour, and the cure of these buns at that time
was evaluated as being only fair~ In contrast, buns using the
- ~ prepolymer of Example 4S (diluted with methylene chloride to
~ 30 reduce the viscosity to permit adequate spraying) containing 33
.~ . :,'. . . '
. ~ .
~ ~ -36- ~
D-9912-1 ~
~4~6~
pounds of the diluted prepolymer blend could be successfully
demolded in 45 minutes, wi~h or without the addition of the
catalyst~ The lowest concentration of the prepolymer/methylene
chloride blend evaluated was 27 pounds of prepolymer blend per
350 pound bun of bonded foam; and, at this rate, demolding in 45
minutes was achieved without the use of the catalyst.
`~ In Example 46, the prepolymer/methylene chloride -~
blend used to form buns at a rate of 3~ pounds of the blend
and one pound of catalyst allowed demolding after only 30 minutes
of cure. The completeness of cure at the time of demolding
was evaluated as being very good. Using the prepolymer composition
of Example 46, the concentration of the prepolymer was gradually
decreased and the foam bun cure evaluated after each prepolymer
concentration change. The lowest prepolymer concentration
.. ~ . ...
; evaluated was 17 pounds of the prepolymer/methylene chloride
blend with no catalyst being added. These buns could be
demolded after 40 minutes of cure; and the foam strength was
evaluated as being very good.
EXAMPLES 47 TO 48
~ These examples illustrate an evaluation on a
- continuous rebonded foam machine and compare a typically
~ ~ used prepolymer composition with a prepolymer composition in
- ~ accordance with the present invention. The~ prepolymer composition
utilized in Example 47 is identified~in Example 46, and this is
compared to a control (Example 48) utilizing a prepolymer (10
` per cent free~NCO~ prepared from TDI and a polyoxypropylene ;
triol having a hydroxyl number of about 56. The results are set
;., .~ ~ : .
~ forth in Table IX below:
, ,
37-
, ~ , . .
:
D-9912-l
TABLE IX
Example No. 4'7 48
% Solids in prepolymer composition 7'7 lO0
% Methylene chloride in prepolymer
composition 23 0
Pounds of shredded foam/minute 77 77
Prepolymer blend in rebonded foam
at start, % 6.9 8.6
Prepolymer blend in rebonded foam
at end, % - , 5.1 .6
Prepolymer solids in rebonded foam
' at start, % 5.3 8.6
Prepolymer solids in rebonded foam
at end, % 3.9 8.6
Rebonded foam cure time, minutes 3 3 '
It should be appreciated that there may be
inaccuracies in the data collected due to problems
- encountered during the trial. Specifically, a prepolymer
mix tank was inoperable, and an a,ir operated pump was used ;
to transfer the prepolymer blend through the spray nozzles
and into the blender. Due to the higher viscosity of the ',
prepolymer used in Example 47, high concentrations of
methylene chloride had to be employed to reduce the viscosity ;
to a level which could be handled. ~, ,
' The data generated do indicate that the prepolymer
' , of Example 47 can be employed at a much lower concentration ,~
' , than the control prepolymer of Example 48. The use levels ~,,,
~, shown would indicate that the prepolymer of Example 47 could
allow a 41 per cent decrease in the prepolymer blend use level
and a 55 per cent decrease in the prepolymer solids use level. '
,, ', . .:
-38-
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.
D-9912-1
~7~
EXAMPLES 49 TO 50
These Examples present an evaluation similar to
Examples 47 to 48, except that the prepolymer composition of
Example 50 employs the prepolymer identified in Example 45 (i.e. -
having a free NCO content of 6.5 per cent).
The data generated are set forth in Table X below:
TABLE X
Exam~le Mo. 49 50 ~ .
. % Solids in prepolymer composition 100 71 :
% Methylene chloride in prepolymer :
composition 0 29
Pounds of shredded foam/minute at start 36 36
Pounds o prepolymer blend/minute at start 2.47 2.28
Prepolymer blend in rebonded foam at ~ :
start, ~ . 6.4 - 6.0
Prepolymer solids in rebonded foam at .. .~.
start, % 6.4 4.3 : -
~ :, ... .
Rebonded foam cure time, minutes :
(at start) 2.5 2.5 ~ :
~, . '~ '
20 Pounds of shredded foam/minute at end ~ 45
Rebonded foam cure time, minutes (at end) 2.5 ~.5
Pounds of prepolymer blend/minute at end - 2.28 : '
.Prepolymer blend in rebonded foam at end, % - 4.8 ..
Prepolymer solids in rebonded foam at ::
end, % _ 3 4
:~Rebonded foam cure time, minutes (at end) - 2
After the completion of the Example 50 run, set forth
in Table X, the prepolymer of Example 49 was again sprayed into-
the shredded foam/prepolymer blender, the prepolymer concentration
0 increased to the 6.4 per cent level successfully used earlier in
.
Example 49 while the rebonded foam cure time was maintained at
39
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D-9912-1
_, =
2 minutes. The rebonded foam produced under these
circumstances was inadequately cured and began to fall
apart (i.e. ~ was dimensionally unstable) upon leaving the
compression area of the machine.
During the trial, rebonded foam production using a
cure time of about 1.7 minutes was attempted using the prepolymer
composition of Example 50. The foam did not bond satisfactorily
at this cure time, and the cure time was thereafter increased
to 2 minutes for the remainder of the trial.
From the data, the prepolymer composition of
Example 50 performed at 25~ lower prepolymer blend concentration
than did the control prepolymer of Example 49. On a prepolymer
solids basis, the concentration of the prepolymer of Example 50
was 47 per cent lower than the concentration of the control
prepolymer used in Example 49.
' ", ,
EXAMPLES 51 TO 55
These Examples demonstrate the preparation of
homogeneous prepolymer solutions according to the present
invention using isocyanates ranging from evaporator tails
to toluene diisocyanate to blends thereof and further illustrates
the necessity of maintaining the oxyethylene content of the ~
polyol within the levels previously described. -
The results are set forth in Table XI:
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D-9912-1
~47~
As can be seen, homogeneous prepolymers can be
: prepared from evapoxator tails, tolylene diisocyanate and blends
thereof when the polyol employed has an exyethylene content of 50%.
.
EXAMPLES 56 TO 60
These Examples illustrate the preparation of prepolymers
employing MDI and polymeric MDI with the polyol described in
Example 51 and show the effects on the character of the prepolymer
when a p~e- or post-filtration is utilizedO
The results are set forth in Table XII: .
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D-9912-1
~76~
As can be seen a homogeneous prepolymer solution
with polymeric MDI having storage stability is prepared when
post-filtration lS utilized. However, when MDI is employed,
while stable, the prepolymer is not ho~ogeneous.
EXAMPLES 61 TO 70
; These Examples further illustrate the preparation
of prepolyme , using as the isocyanate constituent TDR~
~' L polymeric MDI, ~I and various blends.
The results are set forth in Table XIII:
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D-9912-1
As can be seen? a homogenous prepolyme~ was
only formed when TDR was used, with the polyol being one
containing about 50% oxyethylene contenlt. Howe~er, as
set forth in Examples 56 to 60, filtration can provide
homogeneous prepolymers when pol~meric l~DI is used.
,. ~
EXAMPLES 71 to 77
These Examples illustrate the preparation of
laboratory rebonded urethane foams utilizing MDI and
polymeric MDI prepolymers. A TDR prepolymer was also
employed to provide a comparison, The polyol used in ~ -
each Example was that identified in Example 51.
The procedure was the same as previously
describedJ except that 120 gms. of shredded foam and 12
cubic centimeters of water and of the prepolymer were
utilized. ;
The results are set forth in Table XIV:
~ABLE XIV
.
Exa~le No 71 72 73 74 75
- Prep~lymer ~1) MDI MDI Polymeric Polymeric TDRt2
tprepared tprepared MDI MDI
2 0 in Ex. 59) in Ex. 60; tPrePared tprepared
post- in Ex. 57; in Ex. 5B~
filtered) post- pre-filtered)
filtered)
Physical Properties of Rebonded Fbam
Density, lbs.~ft.3 5.17 50398 5.33 4.992 5.436
Tensile strength, 7.15 7.12 2.84 2.32 7.96
psi.
Elongation, ~ . 72 66 42 ~5 65
Ibs.~in. 1.83 2.09 0.82 0.5? l.so
tl) 5wenty per cent nethylene chloride added Obased on weight of p~rpolym~r).
(2) Prepolymer msde using th2 polyol aescribed in Ex. 51; free NCO of 10~.
~46-
.,~.,~ .' - .
D-9912-1
~4~$ : ~
As seen from the above Table, the MDI and TDR
prepolymers provide the resulting rebonded foam with superior
physical properties in relation to prepolymers using polymeric
MDI. Also, the use of filtration does not appear to substantially
increase the properties.
Because of the visual similarity of MDI prepolymers ;
made with polyols having widely varying oxyethylene contents, a
laboratory rebonded foam was made with a MD~I prepolymer ~Example 76)
.
and the polyol of Example 52 (oxyethylene content of 14%). For ~
L0 comparison, a prepolymer having the composition of Example 75 ~ -
was also tested (Example 77).
The amounts of the shredded foam, water and prepolymer
used were as set forth in Examples 71 to 75, and the results were
as follows:
TABLE XV
Example No. 76 ~ 77
Prepolymer MDI TDR
i Physical Properties of~
Rebonded Foam :
Density, lbs/ft.3 5.60 5.55
Tensile Strength, psi. 3.90 8.81
Elongation, % 40 74
Tear strength, lbs./in. 1.22 2.11
The rebonded foam made with the TDR prepolymer has
. . .
superior properties to those utilizing the MDI prepolymer.
Indeed, by comparing Example 77 with Examples 71 and 72, it
can be seen that the MDI prepolymers made with polyols having
oxyethylene contents of 50% provide rebonded foams with properties
markedly superior to the rebonded foams of Example 77 wherein the
polyol used had an oxyethylene content of 14%.
-47-
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