Note: Descriptions are shown in the official language in which they were submitted.
CA 02287121 1999-10-25
A FOAMING COMPOSITION OF SOFT POLYURETHANE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a foaming composition of soft
polyurethane used for the cushion insert for vehicles and more specifically,
to
the foaming composition of soft polyurethane which provides greatly improved
productivity and reduced inferiority owing to the natural crushing of
independent foam cells through chemical method rather than physical method
by reacting resin pre-mix containing polymerpolyol wherein solid polymer
synthesized Erom acrylonitrile or styrene monomer is grafted or dispersed in
polyetherpolyol, polyol wherein polyetherpolyol is mixed, crosslinking agent,
amine catalysts, foaming agent and organic silicon defoaming agent with
organic polyisocyanate.
~ 5 Soft foams for seat cushion mold are divided into cold cure mold foams
and hot cure mold foams depending on the manufacturing method. In the
manufacture of hot cure mold foams, artificial cell-opening process is
unnecessary because the foamed cell is naturally opened through chemical
reaction in the mold. However, in the manufacture of cold cure mold foams,
zo artificial cell-opening process (hereinafter referred to as "crushing") has
been
required because the closed cell is formed. In the manufacture of hot cure
mold
foams, the source solution is injected at 35-40 C of mold temperature and the
foam is solidified at 100-200 C . For cold cure mold foams, the source
solution is
injected at relatively high mold temperature of 50-70 C and the foam is
25 solidified at relatively low temperature of 50-70 C . The resulting foams
contain
a certain amount of closed cells and they cause the constriction of the foams.
Therefore, the cold-cure type mold foams need crushing process. The closed
cells have been opened either by crushing of passing the foams through a
CA 02287121 1999-10-25
2
circular frame with narrower width than the foams or by crushing of
vacuumizing the foams.
The conventional soft foams for cold cure mold are manufactured by
injecting mixture of isocyanate and resin premix in the mold heated to 50-70 C
and solidifying for 3-10 min. The formed foams are processed with crushing in
order to open the closed cells. In spite of the advantage of fast
solidification at
low temperature, the crushing of the closed cells included in the foams render
the increase of the cost of utilities, electric power, manpower and other
expenditures. Therefore, a new technology which excludes crushing by
naturally opening the foams through chemical reaction of isocyanate and resin
premix is being required.
SUMMARY OF THE INVENTION
The inventors made intensive efforts to solve the problems. As a result, it
~ s was realized that with the reaction of resin premix containing
polymerpolyol
wherein solid polymer synthesized from acrylonitrile or styrene monomer is
grafted or dispersed in polyetherpolyol, polyol wherein polyetherpolyol is
mixed, crosslinking agent, amine catalysts, foaming agent and organic silicon
defoaming agent with organic polyisocyanate, the foam yield is greatly
2o improved, and the crushing process becomes unnecessary due to the increased
crushability due to the naturally open cells through chemical reaction.
Accordingly, an object of this invention is to provide a foaming
composition of soft polyurethane which provides greatly improved
productivity and reduced inferiority owing to the natural crushing of
25 independent foam cells through chemical method rather than physical method.
Detailed Description of the Invention
The present invention is characterized by a 1:0.5-1:1.5 equivalence ratio
CA 02287121 1999-10-25
3
mixture of foaming composition of soft polyurethane comprising:
(a) resin premix containing 80-95 wt% of polyol mixture wherein
polyetherpolyol with 2-4 functional groups and molecular weight of
6,000-10,000 and polymerpolyol wherein solid polymer synthesized
s from acrylonitrile or styrene monomer is grafted or dispersed in
polyetherpolyol with the molecular weight of 4,000-8,000 are mixed
in the range of 95:5-50:50 wt%, 0.01-2.0 wt% of amine or glycol
crosslinking agent, 0.2-3.0 wt% of a tertiary amine catalyst, 2.0-5.0
wt% of water and 0.1-2.0 wt% of organic silicon defoaming agent;
and
(b) organic polyisocyanate containing 20-40 wt% of isocyanate group.
The detailed description of the present invention is given hereunder.
The present invention is characterized by manufacturing naturally
~ s crushed soft polyurethane mould foams by the chemical reaction of resin
premix and organic polyisocyanate in the mould.
The foaming composition of the present invention comprises resin
premix and organic polyisocyanate. The resin premix is prepared by adding
crosslinking agent, catalyst, foaming agent and organic silicon defoaming
agent
2o to a polyol mixture of polyetherpolyol and polymerpolyol.
The polyol mixture contained in the resin premix is prepared by mixing
polyetherpolyol which has 2-4 functional groups, of which at least 13 mod % is
primary hydroxyl group, and whose molecular weight is 6,000-10,000 and
polymerpolyol wherein solid polymer synthesized from acrylonitirle or styrene
?s monomer is dispersed or grafted in polyetherpolyol with 2-4 functional
groups,
of which at least 13 mol % is primary hydroxyl group, and whose molecular
weight is 4,000-8,000 in the range of 95:5-50:50 wt%. If the mixing ratio is
beyond the above range, the solidity, formation and physical properties of the
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foams deteriorate. The preferable mixture ratio is 85:15-65:35.
The resin premix is prepared by adding crosslinking agent, catalyst,
foaming agent and organic silicon defoaming agent to the above polyol
mixture.
Glycol or amine crosslinking agents are used. Examples include ethylene
glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,4-
butanediol,
1,6-hexanediol, pentaerythlitol, diethanolamine, triethanolamine,
ethylenediamine, triethyltetramine, methyleneorthochloroaniline,
4,4-diphenylmethanediamine, 2,6-dichloro-4,4-diphenylmethanediamine,
2,4-toluenediamine and 2,6-toluenediamine. The desirable content of the
crosslinking agent is 0.1-2.0 wt% of the total resin premix. If the content is
less
than 0.1 wt%, crosslinkage of the resin premix is insufficient, and if it
exceeds
2.0 wt%, it requires the crushing process due to the increased independent
cells.
For catalyst of the present invention, even though polyurethane foams
i a used for the conventional catalysts can be used, a tertiary amine catalyst
is
desirable. One or a mixture of more than one selected from the group
consisting
of triethylamine, bisdimethylaminoethyl ether, tripropylamine,
triisopropanediolamine, tributylamine, triethylamine, N-methylmorpline,
diethylenetriamine bis(2-(N,N-diethylamino)ethyl)ether and their salts can be
2o used. The desirable content of the catalyst is 0.2-2.0 wt% of the total
resin
premix. If the content is less than 0.2 wt%, the reaction is retarded so that
the
solidification and productivity becomes poor. And if the catalyst content
exceeds 2.0 wt%, there arises a problem such as reduced endurance or fogging
of the foams.
~5 Water used for the foaming agent is desirable to be in the range of 2.0-5.0
wt% of the total resin premix.
Organic silicon defoaming agent plays a role of preventing the
unification or destruction of cells and forming uniform cells, when isocyanate
CA 02287121 1999-10-25
and water react to produce gaseous carbon dioxide and the gas expands to form
cells due to the heat of reaction. Common organic silicon defoaming agent used
for the manufacture of soft cold cure mould foams can be used either alone or
mixed. The desirable content is 0.1-2.0 wt% of the total resin premix.
5 Various stabilizing agent, filling agent, coloring agent, deflaming agent
or settling agent can be used together if necessary.
The said resin premix and organic polyisoisocyanate with 20-40 wt% of
isocyanate groups are mixed in the range of 1:0.5-1:1.5 equivalence ratio and
reacted to obtain opened soft cold cure mould foams. If the isocyanate group
content of the polyisocyanate is less than 20 wt°o, the specific
gravity increases,
and if it exceeds 40 wt%, problems such as solidity and soldifying rate arise.
The mechanical strength (extensibility, heat resistance and tension
resistance) of the opened-cell soft polyurethane foams prepared by the present
invention is superior to the closed-cell soft polyurethane foams.
~ 5 The resin premix and poly isocyanate are mixed in the range of
1:0.5-1:1.5 equivalence ratio and injected to a mold heated to 50-70 C to
prepare
soft cold cure mold foams.
"Index" means a stoichiometric index of isocyanate reacting with the
compound having active hydrogens in the resin premix. Index of isocyanate is
?o calculated by the following equation.
Index of Isocyanate = (Isocyante amount actually used)/ (Theoretically
required isocyanate amount)
After mixing the resin premix and organic polyisocyanate, the mixture is
stirred and inserted into a 200x 200X 200um~ open box to foam freely. The
2s sinking height after the foam is defoamed at the maximum height is
expressed
in % to measure the settling. The reaction mixture is injected into a
400x 400X 100mm aluminum test mould preheated to 50-70 C, 20% excessively
of the minimum filling amount, and the mold is capped. After taking out the
CA 02287121 1999-10-25
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foams 5 min after the stirring of resin premix and organic polyisocyanate, the
crushability is evaluated by measuring the difference of the force required to
compress the same 50% firstly and the force required to compress the same 50%
secondly with universal test machine. Crushability is the measuring of the
force
required to open the closed-cells in the foams and it provides a criterion for
determining if the crushing process is necessary or not. The less the
crushablility, the less the closed-cells.
The test results of the soft polyurethane mould foams prepared from the
present invention show greatly improved productivity and reduced inferiority.
i o The following examples are intended to be illustrative of the present
invention and should not be construed as limiting the scope of this invention
defined by the appended claims.
Examples 1-6
~ s Organic polyisocyanate whose toluenediisocyanate content is 20-~0 wt%
of the total isocyanate and isocyanate group content is 36.5 wt% was used.
Resin premix was prepared by mixing polyol, water, catalyst,
crosslinking agent and organic silicon defoaming agent as in the following
Table 1. 2008 of the resin premix regulated to 25~ 1 C was mixed with 92g of
20 organic polyisocyanate. After stirring vigorously for 5 sec, the same was
injected into a 200X 200X 200mm box. After measuring the settling, the central
part of the foams was bisected by 100X 100X 50utm in order to measure the core
density the following day. The result is shown in Table 1.
Settling and core density decreased with the increase of crosslinking
2s agent.
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Table 1
Examples
1 2 3 4 5 6
Polyol A~> 280 280 280 280 280 280
Polyol Bz~ 120 i20 120 120 120 120
Polyol C'~ 10 10 10 10 10 10
Resin HzO4~ 14 14 14 14 14 14
premix L-30025 2.8 2.8 2.8 2.8 2.8 2.8
SRX-274CG~ 1.2 1.2 1.2 1.2 1.2 1.2
~ t
DABCO 33LV'~ 1.08 1.40 0.40 1.08 1.08 1.08
NTAX A-1"~ 0.6 0.48 0.6 0.6 0.6 0.6
~
I
DEOA''~ 2.0 2.0 2.0 0.0 0.8 4.0
IsocyanateMC-70'~ 198.0 198.0 198.0191.8 194.3 204.2
Index ~ 95 95 95 95 95 95
Settling 8.8 7.1 4.6 15.5 12.2 8.3
(%) ,
Core density 42.0 39.6 37.7 43.9 41.7 37.3
(!cg/
m')
'~ Polyether
polyol
prepared
by additional
polymerization
of propylene
oxide
and ethylene
oxide
with
glycerin
as initiator,
OHV 26n~
KOH/g
'-~ Polymerpolyol
prepared
by dispersing
acrylonitrile
and styrene
monomer
in polyether
polyol
prepared
by additional
polymerization
of propylene
oxide
and ethylene
oxide
with
glycerin
as initiator,
OHV 28n~
KOH/g
'~ Polyether
polyol
prepared
by additional
polymerization
of propylene
oxide
and ethylene
oxide
with
glycerin
as initiator,
OHV 56mg
KOH/g
~~ Distilled
water
or ion
exchange
water
5~ Organic
silicon
surfactant,
Witco
Co.
6> Organic
silicon
surfactant,
Torey
Co.
~ Amine
catalyst,
Air Product
Co.
~> Amine
catalyst,
Tosso
Co.
9> Crosslinking
agent,
diethanolamine,
Korea
Polyol
Co.
1~> NCO%
36.5
Kumho
Mitsui
Chemical
Co. Ltd.
Examples 7-12
Resin premix was prepared as in the following Table 2. 2008 of the resin
premix regulated to 25~ 1 C was mixed with 92g of organic polyisocyanate.
After stirring vigorously for 5 sec, the same was injected to a 200X 200X
200mu~
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box. After measuring the settling, the central part of the foams was bisected
by
100x 100x 50mm in order to measure the core density the following day.
Generally, settling provides the determination of stable cell structure. If a
value
of settling is small, the cell structure is stable and the forming is
favorable.
However, the increased closed cells render the artificial cell-opening
process. If
a value of settling is large, the cell is unstable and formation weight
increases.
Therefore, small settling with large crushability is desirable.
Resin premix was prepared by mixing polyol, water, catalyst,
crosslinking agent and defoaming agent as in Table 2. 640g of the resin premix
regulated to 25~ 1 C was mixed with 2758 of organic polyisocyanate with
50.Ok~;/ tn' of excess density. After stirring vigorously for 5 sec, the same
was
injected to a 400X 400x 100utm aluminum mold. The mold was capped and five
minutes after stirring, crushability was determined by measuring the
difference
of the force required to compress the same 50% firstly and the force required
to
~5 compress the same 50% secondly with universal test machine.
With the increase of crosslinking agent content, the settling and density
decreased and the crushablity became poor. The crushability improved with the
decrease of the ratio of resin catalyst (DABCO 33LV) and urea catalyst (NIAX
A-1). However, it was unfavorable to minimize the density due to the increased
2o settling.
Table 2
Examples
7 8 9 10 11 12
Polyol A 420 420 420 420 420 420
PolyolB 180 180 180 180 180 180
Polyol C 15 15 15 15 15 15
Resin Hz0 21 ~ 21 21 21 21 21
~
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9
premix L-3002 4.2 4.2 4.2 4.2 4.2 4.2
SRX-274C 1.8 1.8 1.8 1.8 1.8 1.8
DABCO 33LV 1.62 2.1 2.4 1.62 1.62 1.62
NTAX A-1 0.9 0.72 0.6 0.9 0.9 0.9
DEOA 3.0 3.0 3 0 0.0 1.2 6.0
IsocyanateMC-70 297.0 297.0 297.0 287.7 291.4 306.3
Index 95 95 95 95 95 95
Settling 8.8 7.1 4.6 15.5 12.2 8.3
(%)
Core density 42.0 39.6 37.7 43.9 41.7 37.3
(k~/ ~
m')
Crushability~~ 0.0 6.5 26.3 0.0 0.0 2.7
~~ Force-to-Crush,
Icg/314cv~
(400x
400x
l0mm),
Difference
of forces
required
to compress
the
sam le
50% firstl
and secondl
Examples 13-18
Resin premix was prepared as in the following Table 3. 2008 of the resin
premix regulated to 25~ 1 C was mixed with 92g of organic polyisocyanate.
After stirring vigorously for 5 sec, the same was injected to a 200x 200X
200mm
box. After measuring the settling, the central part of the foams was bisected
by
100X 100x 50mm in order to measure the core density the following day. Also,
resin premix was prepared by mixing polyol, water, catalyst, crosslinking
agent
and defoaming agent as in Table 3. Resin premix regulated to 25~ 1 C was
mixed with organic polyisocyanate with 55.Okg/ rn' of excess density. After
stirring vigorously for 5 sec, the same was injected to a 400X 400X 100mm
aluminum mould. The mould was capped and five minutes after stirring,
crushability was determined by measuring the difference of the force required
to compress the same 50% firstly and the force required to compress the same
t s 50% secondly with universal test machine.
Crushability varied with the contents of primary, secondary and tertiary
amines. With the increase of primary and secondary amines, the settling and
CA 02287121 1999-10-25
density decreased and the crushability became poor. Namely, with the increase
of primary amines, noncrushing became unfavorable.
Table 3
Examples
13 14 15 16 17 18
Polyol A 490 490 490 490 490 490
Polyol B 210 210 210 210 210 210
Polyol C 17.5 17.5 17.5 ~ 17.517.5 17.5
Resin Hz0 21 21 21 21 21 21
premix L-3002 4.9 4.9 4.9 4.9 4.9 4.9
SRX-274C 2.1 2.1 j 2.1 2.1 2.1 2.1
DABCO 33LV 1.89 2.45 2.8 2.8 2.8 2.8
'
IVTAX A-1 1.05 0.84 0.7 0.7 0.7 0.7
DEOA 7.0 7.0 7.0 0.0 1.4 3.8
IsocyanateMC-70 297.8 297.8297.8 267.6 270.1 273.3
Index 95 95 95 95 95 95
Primary 3.89 3.79 3.76 0.10 0.51 1.81
amine,
tllg KOH/g
Tertiary 2.78 2.85 2.95 1.72 2.13 2.49
amine,
mg KOH/g
Settling 7.6 7.3 8.7 11.0 4.9 5.2
( % )
Core density 43.5 41.3 40.7 49.1 43.2 41.7
(kg/ nt'
)
Excess 54.7 54.9 55.2 55.0 54.9 54.8
density
(kg/ m'
)
Crushability 8.5 17.8 23.0 0 0 0.4
5
As described in detail above, the soft polyurethane foams of the present
invention is prepared by reacting resin premix prepared by mixing polyol,
which is a mixture of polyetherpolyol and polymerpolyol, amine or glycol
crosslinking agent, tertiary amine catalyst, foaming agent and organic silicon
CA 02287121 1999-10-25
defoaming agent with organic polyisocyanate in the predetermined equivalence
ratio. The present invention provides greatly improved productivity and
reduced inferiority owing to the natural crushing of independent foam cells
through chemical method rather than physical method.
