Note: Descriptions are shown in the official language in which they were submitted.
~6t3~
BACKGROUND OF THE INVENTION
Field of the Invention
. .
This invention relates to the production of molded
polyurethane products.
Description of the Prior Art
The particular crosslinker which is found to be
advantageous for use in semiflexible energy absorbing foams
of this invention has been described as a detergent in U.S.
Patent 2,998,452.
U.S. Patent 4,137,265 discloses the Mannich con-
densate precursor of the crosslinker of the present inven-
tion. This patent describes and claims a polyol which is a
propylene oxide adduct of the Mannich condensate precursor
for use in forming rigid polyurethane foams. U.S. Patent
4,137,265 discloses and claims the propylene oxide adduct of
nonyl phenol, formaldehyde and diethanolamine. This product
is useful as the polyol for rigid foams. It was surprisingly
discovered that the ethylene oxide adduc~t of the Mannich
condensate found particular advantage in formulations for
semiflexible foams.
The automotive industry, in particular, is con-
stantly seeking new technologies for increasing the safety of
vehicles, while, at the same time, decreasing the weight of
the vehicles. A major part of the safety program in the
automotive industry is the use of molded polyurethane oams
which absorb energy upon impact. The present invention pre-
sents an improved method of preparing molded polyurethane
foam which in addition to absorbing impact, are lighter in
weight resulting in less vehicle weightO
--1--
o~
SUMMARY OF ~IE INVENTION
The invention ls a method for preparing a molded
flexible polyure-thane product wherein a polyol, a polyiso
cyanate, water and a crosslinker comprising an ethylene oxide
adduct of a Mannich condensate prepared from nonyl phenol,
diethanolamine and formaldehyde are reacted in a closable
mold. The invention is also a molded flexible polyurethane
product prepared by the above method.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the molding of polyurethane products, the
reaction mixture is charged to a riyid mold which ls suf-
ficiently strong that it will not deform when subjected to
the pressure within the mold ater the foaming reaction
starts. Such a mold can be constructed out of metal,
plastic, wood or other materials and combinations of ma
terials. In the practice of my invention, the mold should be
su~ficiently strong to withstand the molding pressures and
also be capable of sealing to the extent that the reaction
mixture is not pushed from the mold during the foaming
process.
To this preheated mold is charged a sufficient
quantity of the foamable polyurethane reaction mi~ture of my
invention to overfill the mold by about 10~ to abou-t 20%. The
term "overfill the mold" means that guantity of the foamable
reaction mixture which is greater than the quantity necessary
to just fill the mold after the reaction is complete. I use
about 10% to about 20% overfill in the practice of my
invention. A greater overfill is possible with very strong
and tightly closed molds and would tend to increase the
density of the foam.
This overfill and tightly closed mold in con-
junction with the reac-tion mixture o~ my invention all
combine to pack the polyurethane foam material and give an
improved cell structure substantially free of voids and also
an improved skin quality of the resulting produc-t. After the
material has foamed, it is allowed to stand in the mold for
about three to nine minutes usually without any further
external heat being necessary to cure the produc-t. O~
course, the foam product can be cwred longer but longer
curing is usually unnnessary. The product is removed from
the mold after this short cure time and a flexible poly-
urethane product is recovered which has a ~ubstantially open
cell structure, a good skin and is subs-tantially ~ree of any
voids.
In order to successfully practice my invention, it
is necessary to use the formulations which I have discovered.
In the one shot process of my invention, the poly-
ether polyol component, the organic polyisocyanate, water,
crosslinker and catalyst are all brought together
simultaneously and allowed to react, foam and cure in the
mold without any additional high temperature curing step.
The polyether polyol component (not the cross-
linker) useful for the practice of this invention may be a
polyol having a functionality of from two to about six and an
eguivalent weight of 1600 to about 2000 having about 80 to
about 100% primary hydroxyl groups.
The polyether polyols useful in the practice of my
invention are prepared by a well known process which involves
the reactlon of the polyhydric initiator such as ethylene
glycol, pLopylene glycol, low molecular weight polypropylene
glycol, -trime-thylolpropane, glycerol, 1,2,6-hexane triol,
sorbitol, pentaerythritol, and the like, or mixtures thereof,
wi-th a lower alkylene oxide such as propylene oxide and
butylene oxide, mixtures thereof, or mixtures of ethylene
oxide with propylene oxide and/or butylene oxide. This
reaction is carried out in a well known manner with an
alkoxylation catalyst, generally an alkali metal hydroxide
such as potassium hydroxide. The reaction is continued until
the product of an approximate desired molecular weight is
obtained. It is necessary to then react the product made as
described above with ethylene oxide in order to acquire the
desired degree of primary hydroxyl group termination of the
polyether chains. This process is described in U.S. Pat.
3,336,242 for example. The percentage of primary hydroxyl
groups terminating the polyether chain is generally increased
by an addition of ethylene oxide alone; howevex, it will be
understood that ethylene oxide mixed with some proportions of
propylene oxide will also achieve this result. Also, it is
within the scope of my in~ention to use a polyether polyol
which may have blocked segments of different alkylene oxides
in the molecule and not solely limiting such segments of
ethylene oxide to the terminal positions.
~ hile higher functionality polyether polyols may be
used, it is preferred to use polyols having molecular weights
of 3500 to about 4400 and about 80% or more primary hydroxyl
groups which are alkylene oxide adducts of a mixture of a
glycol and a triol, for example.
It is especially preferred to use a polyol of about
3900 to 4000 molecular weight which is an ethylene oxide
capped propylene oxide adduct of a mixture of a polypropylene
8(~
glycol of about 400 molecular weight and a propylene oxide adduct of
glycerol having a mol.ecular weigh-t of about 700. The percentage oE primary
hydroxyl groups -terminating this polyol is above abou-t 80%.
The organic polyisocyanate is suitably an organic aroma-tic or
aliphatic polyisocyanate such as 3,3'-dichloro-4,4'-biphenyl diisocyanate,
diphenyl diisocyanate, ethylene diisocyana-te, propylene-1,2-diisocyanate,
1,4-tetramethylene diisocyana-te, p-phenyle:ne diisocyanate, 2,4- and 2,6-
toluene diisocyanates, o,o'-, o,p'- and p,p'-diphenylmethane diisocyana-tes,
hexamethylene di.isocyanate, polymethylene polyphenylisocyana-te, and mixtures
thereof.
Especially preferred organic polyisocyanates useful in the practice
of my invention are those prepared by the phosgenation of the reaction produc-t
between aniline and formaldehyde having a functionali-ty oE 2.2 or greater.
While func-tionalities around four and above are possible, they are not read-
ily attainable by known processes. It is preferred to use isocyanates having
functionalities of about 2.2 to about 3.5 and an especially preferred range is
between 2.2 and 2.8. Useful isocyanates are produced by phosgena-ting amine
precursors formed in the process described in United States Patents
2,683,730 and 3,362,979, for example.
The foams oL this invention also contain a cross-linker which is
the ethylene oxide adduct of the Mannich condensate of nonyl phenol, di-
ethanolamine and formaldehyde. Preparation of this Mannich condensate may be
found in United States Patent 4,137,265. To this Mannich condensate is added
ethylene oxide in an amount to give adducts with hydroxyl number values of
230 to
-- 5 --
500 (as meq KOH/g sample). The preferred amount of ethylene
oxide yielded an adduct with hydroxyl number value of 470-480
(as meq KOH/g sample).
The polyol component and the organic isocyanate
component are mixed in the reaction mixture in such pro-
portions that the ratio of isocyanato groups to hydroxyl
groups, commonly known as isocyanate index, is from 0.85 to
about 1.05 with an especially preferred isocyanate index
being about 0.95. The ratio of isocyanato groups to hydroxyl
groups includes also any water that is present in the
foamable reaction mixture as well as the hydroxyl groups in
the crosslinker of the invention.
Water is used to produce the blowing agent and/or
adjust the density of the foam in the practice of this in-
vention. It is an advantage to use the crosslinker of myinvention so that a higher amount of water may be used and
still obtain acceptable foam. It is preferred to use about
2.5 parts by weight of water per 100 parts of polyol com-
ponent and it has been found that best results are obtained
when the water xange is from about 2.2 to about 4.5 parts by
weight per 100 parts of polyol component.
The catalysts useful in my invention includes those
normally employed in polyurethane foams including tertiary
amines and organometallic compounds. I-t is within the skill
of the ordinary worker in the art to choose a workable
catalyst system.
E'or example, a partial list of use~ul tertiary
amines include trialkylamines (e.g. trimethylamine, tri~
ethylamine), heterocyclic amines~ such as N~alkylmorpholines
(e.g., N-methylmorpholine, N-ethylmorpholine, etc.~, l,~
~3L61~
dimethylpiperazine, triethylenediamine, etc., aliphatic
polyamines, such as N,N,N'N'--tetramethyl-l, 3-butanediamine.
Also useful are those catalysts used in the examples which
follow. Although the improvement is noted with a variety of
catalysts, especially preferred is the two mole propylene
oxide adduct of dimethylaminopropylamine.
A partial list of organic tin compounds used as
catalysts which are particularly useful in making flexible
foams may suitably be a stannous or stannic compound, such as
a stannous salt of a carboxylic acid, a trialkyltin oxide, a
dialkyltin dihalide, a dialkyltin oxide, etc., wherein the
organic groups of the organic portion of the tin compound are
hydrocarbon groups containing from 1 to 8 carbon atoms. For
example, dibutyltin dilaurate, dibutyltin diacetate,
diethyltin diacetate, dihexyltin diacetate, di-2-
ethylhexyltin oxide, dioctyltin dioxide, stannous octoate,
stannous oleate, etc., or a mixture thereof, may be used.
The catalysts useful in the preparation of poly-
ether polyurethane foams described herein based on the
combined weight of the hydroxyl-containing compound and
polyisocyanate, are employed in an amount of from about 0.05
to about 2.0 weight percent. Preferably, the amount of
catalyst used is 0.1-1.5 ~eight percent.
The catalysts used in this invention may be used
either alone or in a mixture with one or more other catalysts
such as other tertiary amines or with an organic tin compound
or other polyurethane catalysts.
C'onventional formulation ingredients may also be
employed as needed, such as, for example, foam stabilizers
also known as silicone oils or emulsifiers. The foam
8C~
stabilizer may be an organic silane or siloxane. For
example, compounds may be used having the formula:
RSi[o-(R SiO)n-(oxyalkylene)mR]3
wherein R is an alkyl group containing from 1 to 4 carbon
atoms; n is an integer of from 4 to 8; m is an integer of 20
to 40; and the oxyalkylene groups are derived from propylene
oxide and ethylene oxide. See, for example, U.S. Pat. No.
3,194,773.
It is within the scope of the present invention to
utilize an extraneously added iner-t blowing agent such as a
gas or gas-producing material. For example, halogenated low-
boiling hydrocarbons, such as trichloromonofluoromethane and
methylene chloride, carbon dioxide, nitrogen, etc., may be
used. The inert blowing agent reduces the amount of excess
isocyanate and water that is required in preparing flexible
urethane foam. Selection of the proper blowing agent is well
within the knowledge of those skilled in the art. See for
example U.S. Pat. No. 3,072,082.
As the examples which follow demonstrate, it is
advantageous to use the present crosslinker which is essen-
tially a pentol in conjunction with other low molecular
weight materials containing hydroxyl groups having hydroxyl
numbers ranging from about 200 to 2000. For example, low
molecular weight diols such as ethylene glycol, propylene
glycol and dipropylene glycol have been found to be useful as
well as carbamate diols and difunctional amine polyols as
used in Examples XI-XV which follow. Other similar materials
are also useful in conjunction with the crosslinker of the
invention.
O
In the examples which follow, the invention will be
demonstrated and many of the improvements will be apparent
from the use of the crosslinker of the invention. ~owever,
many of the improvements are of a more subjec-tive nature
which are not demonstrable by objective tests which are
recognized in the art. I have noticed many improvements and
advantages to the use of this crosslinker in semiflexible
formulations including:
(1) significant improvement in moldability
characteristics,
(2) improved material utilization (lower density
foam,
(3) reduced number of voids in the molded parts,
(4) superior processing with lessened sensitivity
to machine conditions,
(5) excellent cell structure and uniform appear-
ance,
(6) superior adhesion to vinyl skins used for
molded parts,
(7) significantly improved water utilization
latitude,
(8) improved cure characteristics (shorter demold
time),
(9) lower closed cell content which results in
foam which does not shrink,
(lO) excellent compatibility of the entire formu-
lation which promotes uniform processing.
8C~0
E X A M P L E
.. ..
Preparation of Crosslinker
A ~annich condensate was prepared from 1.0 moles
nonylphenol, 2.0 moles of diethanolamine, and 2.0 moles of
formaldehyde, and water was removed by vacuum stripping.
(See U.S. 4,317,265).
To 61.8 lbs. of the s-tripped Mannich condensate,
charged to a 15 gallon kettle and heated to 115C., was added
25.5 pounds of ethylene oxlde at 115-125C., over a period of
one hour and twenty minutes. The reaction mixture was
digested at 110C for an additional one hour and ten minutes.
Unreacted oxide was removed by vacuum stripping and the
product was discharged after cooling. The product viscosity
was 21,000 cps, water content was 0.05%, hydroxyl number was
475. This product will be reerred to as Crosslinker A and is
the crosslinker of the invention.
--10--
E X A M P L E S I I - V
These examples demons-trate use of the crosslinker
as the sole crosslinker in formulations designed for semi-
flexible instrument panel foam. These cup pours were the
initial pours made to determine -the nature and foaming
behavior of this material. In these and following examples,
the components were weighed into a 5 in. (tall) paper cup,
blended with stirring; MONDIJR~) MR was added, the mixture
stirred thoroughly and 100-110 g of the mixture was poured
into a second 5 in. cup and allowed to foam and rise. Rise
time = time in seconds for foam to rise to top of cup. Tack
Free - time in seconds for foam surface to freely release
when probed with an object such as a tongue depressor or
pencil.
15 Formulation, pbw II III IV V
THANOL(3SF-39501 100 . O100 . O100 . O100 . O
Crosslinker A 10.0 8.0 8.0 5.0
Water 2 2.2 2.5 2.5 2.5
THANCAT~DME3 -- 1.0 -- --
20 THANCAT~DPA -- -- l.5 1.2
Carbon Black Paste 2.0 2.0 2.0 2.0
A-Comyonent
MONDUR MR4 47.0 49.0 49.0 45.5
Cup Data 6
Rise Time, Sec. 260 48 50 75
Tack Free, Sec. 420 150 120 225
Cup Height, inches5 -- 6.8 6.7 6.9
Cup Weight, grams -- 75.8 76.6 71.3
Ethylene oxide capped, propylene oxide adduct of mixed diol
and trihydric initiators of about 3950 molecular weight,
2Product of TE~`CO CHEMICAL CO.
3N,N-DimethylethanolamineJ Product of TF.XACO CHEMICAL CO.
4Two mole propylene oxide adduct of dimethylaminopropylamine.
Polymethylene polyphenylisocyanate, Product of Mobay Chem.
Corp.
5Cup Height = Total height of risen foam at final rise
height. Cup Weight = Weight of foam in cup after top of
foam is cut off even with top rim of cup. This value
provides free rise density and the cup height and weight
are indicative of the potential foam usage when the foam
compound is molded. In later examples, the mixed foam
components are poured (Fill Weight, g) into a mold which
contains parallel channels and the rising foam is forced
to flow around successive 180 turns as it progresses
through the channels. That which flows beyond the last
channel is trimmed off (part weight, g). This method
provides data regarding moldability, foam utilization, foam
pressure, potential shrinkage problems (closed cell foam),
6and potential gassing problems.
Foams in Examples II-V exhibited fine uniform cell struc-
ture, excellen-t reaction profile. A typical formulation
used commercially (see Example X) exhibits rise and tack
free times of 80, 330, respectively.
-12-
E X A M P L E S V I - X
. . . _ . . _
The examples demonstrate use of the crosslinker o~
the invent~on as an additive for semiflexible foam to promote
better cell structure and fu~ction as a surfactant and cell
control a~ent.
Formulation, pbw VI VI:[ VIII IX X
B-Component
THANOL S~395097.5 97.5 97.5 100.0 97.5
PolyesterlPolyol
L-1217 2 2.5 2.5 2.5 __ 2.5
NIAX~50-970 5.8 5.0 5.0 -- 6.0
Crosslinker A 0.2 0.5 1.0 6.0 --
Water 3 2.2 2.2 2.2 2.5 2.2
THANCAT~DD 4 0.35 0.35 0.35 0.30 0.35
T~ANCAT~DMDEE0.35 0.35 0.35 0.30 0.35
Carbon Black Paste 2.0 2.0 2.0 2.0 2.0
A-Component
MONDUR MR 51.3 50.4 50.4 46.5 45.5
Cup Data
Rise Time, Sec. 74 76 80
Tack Free, Sec. 330 330 330
Cup Height, inches 7.3 7.3 7.3
Cup Weight, grams 69.3 69.8 73.0
Molding Data
Fill Weight, grams 310 305 305 3025 310
Part Weight, grams 301 288 302 275 306
2Product of WITCO CHEMICAL CO.
3Product of UNION CARBIDE CO., a crosslinker.
2-Dimethylaminoethyl-3-dimethylaminopropyl ether, Product of
4TEXACO CHEMICAI. CO.
5B,B-Dimorpholinodiethyl Ether, Product of TEXACO CHEMICAL CO.
Note superior usage (less weight of foam to fill the mold) when
Crosslinker A is substituted direc~].y in a typical commercial
formulation (Example X). This superior usage results from
utilization of higher water levels which is possible with
the use of this crosslinker. Also in these examples, ~hen
Crosslinker A is used, improved cell structure resulted.
-13-
E X A M P L E S X I - X V
me examples demonstrate use of diluent crosslinkers. 'mese cross-
linkers are much lower in functionality than our Crossli~cer A and are sub-
stituted into the formulation for part of the Crosslinker A to decrea~se the
overall crosslink density and at the same time maintain the required load
bearing properties. I~proved u~sage results while inclusion of the Cross-
linker A provides the improvem~nts in oe ll structure, moldability and other
factors mentioned earlier.
Formulation, pbw XI XII XIII XIV XV
B-Component
'~HANOL SF-3950100.0 100.0 100.0 100.0 100.0
Crosslinker A 16.0 6.0 6.0 6.0 6.0
THANOL(~ C-150 2.0 -- -- -- --
THANOL ~C-1651 -- 2.0 -~
THANOL ~C-200 2 ~~ ~~ 2.0 -- --
THANOL ~TR-380 -- -- -- 2.0 --
Dipropylene Glycol -- -- -- - 2.0
Water 2.5 2.5 2.5 2.5 2.5
THANCAT DPA 1.2 1.2 1.2 1.2 1 2
Carbon Black Paste 2~0 2.0 2.0 2.0 2 0
A-Component
MONDUR MR 50.2 49.8 49.4 48.2 50.5
Cup Data
Rise Time, sec. 60 65 63 67 65
Tack Free, sec.165 195 180 210 195
Cup Height, inches 7.03 7-33 7-33 7-23 7-5
Cup Weight, grams69.5 68.5 72.0 74.0 68.43
Car~amate diol crosslinkers. 150 is 2-hydroxyethyl~2-hydroxyethyl
c æbamate, 165 is 2,hydroxyethyl-2-hydroxypropyl carbamate, 200 is
2-hydroxyethyl-2-[2-hydroxyethoxyethyl] carbamate. U.S. 3,595,814 describes
2these products. Products of TEXACO CHEMICAL CO.
Difunctional aminopolyol crosslinker which is the reaction product of ani-
line and about 6 to 7 moles of ethylene oxide. See U.S. 4,067,833. Product
~of TEXACO CHEMICAL CO.
~Note cup weight (foam utilization) compared wi-th Examples 3 and 4; improved
usage results from incorporation of these diluent crosslinkers. We s-till
maintain superior reaction profile and cell structure.
-14-
l,,i
.~
o
E X A M P L E S X V I - X X I I
.. . . ~ .,
The examples demonstrate the use o~ diluenk cross-
linkers in semiflexible instrumental panel foam. In these
examples lower -t~tal crosslinker con-tents are used which
provides softer foam than that described in Examples XI - XV.
Formulation, pbw _ XVII XVIII XIX XX XXI XXII
B-Component
THANO~ SF-3950 100.0 100.0100.0100.0100.0100.0 100.0
Crosslinker A 3.6 3.63.6 3.0 2.4 2.5 2.0
Dipropylene glycol 2.4 -- -- --
Propylene glycol -- 2.4 2.4 2.0 1.6 2.5 2.0
Water 2.5 2.52.5 2.5 2.5 2.5 2.5
THANCAT~DPA 1.0 1.01.6 1.6 1.6 1.6 1.6
Carbon Black Paste2.02.0 2.0 2.0 2.0 2.0 2.0
A-Component
MONDUR MR 48.3 51.651.8 49.9 48.0 51.0 48.9
Cup Data
Rise Time~ sec. 92 82 60 63 66 60 64
Tack Free, sec.l 270270 165 180 210 180 195
Cup Height, inl 7.47.5 7.7 7.7 7.8 7.8 7.9
Cup Weight, g. 68.666.0 63.6 63.2 63.6 61.5 62.1
Nolding Data
Fill Weight 307 305313 307 306 312 308
Part Weight 301 399308 300 296 294 308
lWe obtain superior foam utilization when diluent crosslinkers
are used, yet we do not sacrifice any of the benefits
offered by Crosslinker A when its concentration is reduced.
-15-
8G~
E X A M_P L E S X X I I I - X X I ~
These exampLes demonstra-te ln~luence of higher
water levels in the formulations. Hlgher water levels give
lower denslty foam, better foam usage, less weight per part.
Hlgher ~7ater levels in a ~ormulation usually lead to poorer
moldability, increased voids, ~ut the use of Crossllnker A
allows these higher levels to be used.
Formulation, pbw ~YXIII XXIV XXV XXVI XXVI:[ XXVIII XXIX
B-Component
THANOL SF-3950100.0100.0100.0 100.0 100.0 100.0 100.0
Crosslinker A3.0 3.0 3.0 3.0 3.0 3.0 6.0
Propylene Glycol 3.0 3.0 3.0 3.0 3.0 3.0 --
Water 2.5 2.6 2.7 2.8 2.9 3.0 3.0
TH~NCAT DPA1.2 1.2 1.2 1.2 1.2 1.2 1.2
Carbon Black Paste2.0 2,0 2.0 2.0 2.0 2.0 2.0
A-Component
MOND~R MR 53.1 54.4 55.3 51.1 58.8 59,8 54.3
Cup Data
Rise Time, sec. 76 75 74 75 68 65 60
Tack Free, sec.l 240 240 240 240 240 210 240
Cup Height, in 7.7 7.9 7.9 7.9 8.0 8.3 8.1
Cup Weight, g,l 63.7 62.3 60.9 60.1 59.9 54.8 58.1
~ Molding Data
; Mold Fill Wt.l 318 322 323 322 324 330 --
Mold Part Wt.298 286 28`4 286 280 263 --
Obvious benefits result from higher water levels. (The
normal range in commercial foLmulations is 1.8 to 2.2.)
Later examples will show that levels above the standard 2.2
yield good moldability systems.
-16-
E X A M P L E S X X X X X X X V I
The examples demons-trate the use of formulations
(described in previous examples in laboratory hand mix
studies) in machine pours, wherein cups, molds and instrument
panel pads are poured. Although cup pours and mold pours are
used to indicate moldability, potential reduction of void.s,
foam usage and higher water utility; machine poured pads
fully illustrate these things in actual end use.
17-
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