Note: Descriptions are shown in the official language in which they were submitted.
~133200
-- 1
~ his invention relates to a vibration isolator
that is effective in damping vibration or preventing
the transmission of vibration, and particularly to a
vibration isolator consisting of a microcellular poly-
urethane elastomer which can be effectively used indamping vibrations that are set up under high loads or
can be effectively used in isolating the transmission
of vibration that takes place between the source of the
vibration ~nd the members that support said source. -
It has been known hitherto to use as vibration
isolators for damping or isolating vibration those ma-
terials consisting principally of natural rubber or
synthetic rubbers. For example, a rubber vibration iso-
lator is used for preventing the transmission of the
rotary and reciprocating motions of such equipment as
compressors~ presses~ etc. to their supporting bed.
~hese vibration isolators are designed to achieve the
isolating e~fect by transmitting the vibratory energy
from the vibration producing source to a rubbery elastic
member where the effect of isolating the transmission of
vibration is achieved by the deformation of the elastic
member and internal loss.
In using this type of vibration isolator for
the purpose of damping or isolating the transmission of
vibration, the prevention of vibration or its transmis
sion can be achieved by insertion o~ a vibration isolator
(rubber vibration isolator) between the source of
vibration and its supporting members when the
1133200
-- 2 --
dis~placement by the vibration is only in a uniaxial
direction, say the direction of~cceleratio~ of gravity.
However, the vibration of the vibratory source usually
occurs in two or more axial directions, for example in
triaxial directions with the direction of acceleration
of gravity as one of the axes, and thus a vibratory source
that is supported on a vibration isolator is in an ex-
tremely instable state as a result of the vibratory ac-
celerations in directions other than the direction of
acceleration of gravity. ~o wit, in the case of a vibra-
tory source having a high center of gravity, there is the
danger of its toppling. Again, it becomes impossible to
secure its position as a result of a thrusting force in
a horizontal direction incident to the vibrationO In
other words, it is difficult to firmly unite an elastic
member such as a vibration isolator with a vibratory
source or its supporting bed.
As one solution, there has been conceived a
method consisting of covering the bottom of a rigid base
such as a concrete sheetlike member with a vibration
isolator followed by embedding this in a recess of the
supporting bed and thereafter installing the vibratory
source atop this base and securing it thereto. ~he
vibratory source and the base can easily be firmly united
by means of such binding hardwares as bolts. Cn the
other hand, the base is held in the surface of the bed as
a result of its having been embedded in a recess of the
supporting bed. In this case the vibration isolator at
.
.. .. .
. ~
;~
1~33200
-- 3 --
the bottom of the base supports the load consisting of
the vibratory source and the vibration isolator at the
sides of the base and in contact with the sides Or the
recess counters the thrusting force of the vibration in
the hori7.ontal direction.
It was however found th3t a serious problem
arose when this..~ethod was carried out. Since the
vibration isolator at the bottom of the base is embedded
in a recess of the bed surface accordlng to the above
method, deformations in directions other than that re-
sulting from the load in a perpendicular axis to the
base and the bed surface are substantial~.y contrained.
Hence, under these con~itions, the volumetric changes of
the vibration isolator will be coerced by the vibration
of the base. On the other hand, the conventional vibra-
tion isolators which consist principally of nautral
rubber or synthetic rubbers have a dense structure, and
thus di~ficulty is experienced in bringing about a
change in their volume. Hence, the vibration isolator
being in a state in which its volumetric deformation is
constrained loses its functions as a vibration isolator.
In accordance wi-th our experiment, when a
square vibration isolator consisting principally of chlo-
roprene rubber having a thickness of 25 mm and whose one
?5 side was 20 Gm was compressed between flat plates in a
free state without restraining its volumetric chaage, a
compressive strength of 520 kg was required in compress-
in~ it 1 mm, and a co~pressive strength of 1300 kg was
11~33200
-- 4 --
required in compressing it 2.5 mm. In this case, the
spring constant between the strains 4% - l~/o is calcula-
ted to be 5.2 tons/cm, but the spring constant rises to
20.8 tons/cm when the compression is carried out with
constraint such as to cause a reduction in the volume by
the compression. ~he rise in the spring constant thus
reaches a value of four times. It is thus impossible
to achieve damping vibration or prevention of the trans-
mission of vibration by using the conventional vibration
isolators in a state such as described,
The conventional vibration isolator also has
the drawback that there is a change in its properties at
the time of compression as a result of a change of its
geometrical configuration. ~o wit, when the aforemen-
tioned chloroprene rubber-t~pç vibration isolator, which
is a platelike member having the dimensions 20 cm x 20
cm x 25 mm is compressed while allowing its free deforma-
tion, the spring constant per unit area is 13 kg~cm3
between the strains 4% - l~o~ as hereinbefore indieated.
However, when a member having the dimensions 50 cm x 50
cm x 25 mm is used, and the measurement is made in the
same manner, the spring constant Per unit area shows a
value of 24 kg/cm3, and the rise corresponds to 1.8
times. ~his is believed to be for the reason that in
the case of the conventional vibration isolators there
occurs a markedly different volumetric deformation
depending upon the shape of the vibration isolator even
when the compression is carried out while allowing the
1133200
free deformation of the vibration isolator. This poses
an exceedingly troublesome problem from the standpoint
of designing a vibration isolator.
Our researches with the view of solving the
problems indicated hereinbefore led to the discovery that
a polyurethane elastomer as specified below, i.e., a
microcellular polyurethane elastomer having a bulk
density of 0.3 - 0.9 g/cm3 that is obtained by reacting
in the presence of water as -the blowing agent
(a) an organic polyisocyanate,
(b) a polyether polyol having an average number
of functional groups of 2.5 - 3.5 and a number average
molecular wei@ht of 4500 - 8500, and
(c) a chain extender,
in such a ratio that the i~CO index is 90 - 110 and the
concentration of the chain extender, based on the total
weight of the three components (a), (b) and (c), is
(0.4 - 2.0) x 10-3 equivalent/gram was extremely suitable
for use as a vibration isolator, especially an isolator
of vibrations that are encountered under high loads.
~here is thus provided in accordance with this
invention a vibration isolator consisting of the above-
specified microcellular polyurethane elastomer.
~he microcellular polyurethane elastomer of
this invention has a bulk density of 0.3 - 0.9 g/cm3,
preferably 0~5 - 009 g/cm3, and more preferably 0.65 -
0~85 g/cm3~ Hence, those having a bubble content of 10 -
70%~ preferably 10 - 5~/0, and more preferably 15 - 35%,
~133200
-- 6 --
are used. In a microcellular polyurethane elastomer
of this type the internal bubbles are compressed by a
compressive load even under conditions where the de-
formation of the elastomer in directions other than the
direction along the axis of the load is constrained.
Hence, a volumetric deformation easily takes place, with
the conseguence that a great rise in the spring constant
that is seen in the conventional ,isolators can be avoided.
Simil~rly, under conditions where deformation is freely
permitted, there is hardly any change in the spring
constant per unit area even when there is a change in
geometric configuration, i.e. a change in the pressure-
receiving area. For example, when a microcellular
polyurethane elastomer having a bulk density of 0.5~
g/cm3, as a plate having the dimensions 10 cm x 10 cm x
25 mm, was compressçd with freedom of deformation, its
spring constant per unit area between the strains 4%
l~/o was 4.2 kg/cm3, but when this was compressed while
constraining it such as to bring about a volumetric com-
? pression~ the spring constant rose to 5.5 kg/cm3, a value
only 1.30 times~ ~urther, when the same microcellular
polyurethane elastomer was compressed under freedom of
deformation but using a plate having the dimensions 50
cm x 5G cm x 25 mm, the rise in the spring constant per
unit area was about 1.1 times. Thus, superior effects
in absorbing vibration can be obtained by using this t~pe
of ~microcellular polyurethane elastomer even in those
cases where the volumetric deformation is in a restricted
1133ZOO
or constrained state.
While not only the bulk density but also the
physical and chemical properties of the microcellular
polyurethane elastomer can be varied over a wide range
by a choice of its constituent components, it goes with-
out saying that in a case where the elastomer is to be
used as a vibration isolator as in this invention the
conqtituent components must be so chosen as to be the
optimum in respect of durability and isolation properties.
~he makeup of the low foam polyurethane elastomer sui-
table for achieving the objects of the present invention
will now be fully described.
~ he microcellular polyurethane elastomer used
in this invention is formed by reacting (a) an organic
polyisocyanate, (b) a polyether polyol having an average
number of functional groups of 2.5 - 3.5 and a number
average molecular weight of 4500 - 8500, and (c) a chain
extender, in the presence of water as the blowing agent
and a urethanation catalyst and, as required, a foam
stabilizer.
It is extremely important that the polyether
polyol used in this invention is one having an average
number of functional groups of 2.5 - 3O5 and a number
average molecular weight ranging between 4500 and 8500.
When the average number of functional groups is less
than 2.5~ the permanent compression set of the resulting
microcellular polyurethane elastomer, an important pro-
perty when the elastomer is to be used as a vibration
1133200
-- 8 --
isolator, becomes great to make i-t unfit for use. In
the case of the polyuretlaane elastomers that are used
for shoe soles, the polyether polyols having a number of
function~l groups close to 2 are used in most instances,
but for obtaining an elastomer for vibration isolator
having a small permanent compression set that is in agre-
ement with the obJect of this invention the average
number of functional groups must be at least 2.5. On
the other ha~d, when the average number of functional
groups of the polyether polyol used exceeds ~.5, the re-
sulting polyurethane elastomer not only tends to become
extremely hard, but also the possibility of the rupture
of the resulting elastomer by means of vibratory com-
pression increases. Thus, the number of functional
groups suitably ranges from 2.8 to 3.3, 0~ the other
hand, when the number average molecular weight of the
polyether polyol is less than 4500, only a polyurethane
elastomer whose vibration energy absorbing properties
are especially low can be obtained~ ~his is believed for -
the reason that the chemical crosslinking point density
becomes high tO result in the elastomer approaching the
behavior of a perfect elastic body~ Qn thç other ha~nd,
when thç number averag~ molecular weight exceeds 8500,
this also is undesirable since the elastic properties of
the resulting polyurethane elastomer suffer to result in
a tendency to plastic deformation taking place, and
especiall-y since the permanent compression set become$
great. Thus, a preferred range for the number average
1133200
molecular weight o~ the polyether polyol to be used is
one ranging from 4500 to 6500
Usable as such a polyether polyol are those
which are known per se. Included are, for example, the
polyether polyols obtained by addition polymerizing an
oxyalkylene compo~md of 2 - 4 carbon atoms such as
ethylene oxide or propylene oxide to the lower aliphatic
polyhydric alcohols of 2 - 6 carbon atoms such as gly-
cerol and trime-thylolpropane or to a low molecular weight
active hydrogen compound containing at least two active
hydrogen atoms such as ethylene diamine.
Further, for obtaining a microcellular poly-
urethane elastomer having good vibration isolation pro-
perties it is essential that a chain extender be used in
this invention. ~ chain extender by reacting with the
isocyanate forms by means of a urethane bond or a urea
bond a hard segment that is principally an inter-hydrogen
bond. It is thus an important factor controlling the
properties of an elastic body. According to our studies,
it was found that in combining the chain extenders with
the foregoing polyether polyols the former was suitably
incorporated in such an amount that when expressed as
equivalent concentration of the active hydrogen contained
in the chain extender per unit weight of the polyurethane
elastomer to be obtained, it would be in the range 0.4
x 10-3 - 2.0 x 10-3 equivalent/g, preferably 0.4 x 10-3
l.0 x 10-3 equivalent/g. I~hen this equivalent concen-
tration is less than 0.4 x 10-3 equivalent/g, the strength
. ~ :
1133200
-- 10 --
of the resulting ~microcellular polyurethane elastomer
is extremely low to make it fit for practical use. On
the other hand, when this concentration is higher than
2.0 x 10 3 equivalent/g? while there is an enhancement of
the strength of the resulting polyurethane elastomer,
the elastomer becomes extremely hard. In addition, as
a fatal defect, there is an aggravation of the permanent
compression set and the repeated compression fatigue
properties. It is believed that this fact indicates that
an increase in the density of the physical crosslinking
points such as inter-hydrogen bonds is undesirable when
the elastomer is used for such purposes where it is sub-
jected to repeated compression stresses such as for a
vibration isolator.
As such chain extenders, usable are the rela-
tively low molecular weight compounds of essentially 2 -
4 functionality, particularly 2 functionality, i.e, the
diols and the diamines, examples of which are ethylene
glycol? propylene glycol, propanediol, butanediol,
hydroquinone, hydroxyethylquinone ether, methylenebis-
(o-dichloroaniline), quadrol, ethylenediamine and tri-
ethanolamine, of which preferred are the straight chain
alkylene diols, particularly ethylene glycol or 1,4-
butanedial.
On the other hand, usable as the organic poly-
isocyanates are those which are usually used in the
urethane elastomers. Examples are such polyisocyanates
as 4,4'-diphenylmethanediisocyanate (MDI), naphthylene-
1133ZOO
11 --
diisocyanate (NDI), tolylenediisocyanate (~DI) and hexa-
methylenediisocyanate. These can also be used as mixtures
of two or more thereof. Of these polyisocyanates1 pre-
ferred are the aromatic diisocyanates such as MDI, NDI
and ~DI, particularly preferred being MDI. Rather using
~iDI in its crude state, it is advantageously used in its
pure state.
Again, the polyisocyanate can also be used as
a precursor, iOe. a prepolymer or a semiprepolymer, con-
densed in advance with the foregoing polyether polyol.In either case, the organic polyisocyanate is advantage-
ously used in an amount, expressed as the ~C0 index, of
90 - 110, preferably 95 - lO~o
lJater can be used as the blowing agent in pro-
ducing the (microcellular polyurethane elastomer of thisinvention. While the amount of the blowing agent re-
quired for obtaining the polyurethane elastomer having
a bulk density of 0~3 - 0.9 g/cm3 as intended by the
instant invention can be readily determined by those
skilled in the art, the amount of blowing agent usually
ranges from 343 x 10-4 to 4.-' x 10-3 grams per unit weight
(g) of the polyurethane elastomer to be obtained.
As the urethanation catalyst, those usually
used in the urethanation reaction, io e. the tertiary
amine compounds and the organometallic compounds, can be
used. Examples include such compounds as triethylene-
amine, diazabicycloundecene, n-methylmorphine, N,N-
dimethylethanolamine, tin octylate and dibutyl tin
-.
'
1133200
_ 12 --
laurate. While the amount of catalyst used can be
varied over ~ wide range in accordance with the reaction
speed desired, it must be suitably adjusted in accordance
with the amount of polyurethane elastomer to be foamed
and the atmospheric conditions (temperature and humidity).
This amount can be easily determined.
~ he invention microcellular polyurethane
elastomer can suitably contain a foam stabilizer such as
a silicone-type surface active agent. It can also contain
such pigments as carbon black.
~ he several components described hereinbefore
can be reacted by methods which per se are known. ~or
example, the liquids A and B of the following compositions,
after intimate mixing, are poured into a suitable mold
where foaming and cure of the elastomer is allowed to
proceed. ~his foaming and cure can usually be performed
at room temperature, but it can also be carried out while
heating the mixture to a temperature up to about 70C.
~he foaming and cure is completed in roughly 1 - 2 hours,
after which the resulting elastomer can be removed from
its mold.
" 1133200
-- 13
Com~osition of 1~
Polyether polyol (a glg~erol/
propylene oxide/ethylene oxide
copolymer addition p~o~uct;
number average molecular
weight = 6500) 1000 parts by weight
Ethylene glycol
(chain extender) 0.5-20 parts by weight
Water (blowing agent) 0.1-1.5 part by weight
Foam stabilizer (e.g. a
silicone-type surface
active agent) 0.1-1 part by weight
Triethylenediamine
(urethanation catalyst) 0.1-0.5 part by weight
Composition o~ liquid B
Polyisocyanate/polyether
polyol prepolymer (e.g. an
isocyanate terminated
precursory condensation
product of 4,4'-diphenyl-
methanediisocyanate and
the above polyether polyol; NC0 Index
free NC0 content = 16 wt.%) 90 - 110
A vibration isolator consisting of a micro-
cellular polyurethane elastomer can be thus obtained.
A major portion of the bubbles in the microcellular poly-
urethane elastomer thus formed are independent bubbles.
~he desirable properties of this elastomer are as follows
(1) Bulk density:
0.3 - 0~9 g/cm3, preferably 0.65 - 0.85 g/cm3.
(2) ~ensile strength:
At least 5 kg/cm2, preferably 6 - 15 kg/cm2O
(3) ~pring constant:
At least 0~1 ton/cm, preferably 0.5 - 1.5 ton/cm~
1~33Z00
- 14 _
~4) Permanent compression set:
25% at the most, and preferably not more than
1 5~c .
(5) ~atigue strength:
2.0 mm at the most, and preferably not more
than 1.0 mm.
Another superior characteristic that the
vibration isolator consisting of the microcellular poly-
urethane elastomer provided by this in~ention possesses
is its temperature characteristic. ~o wit, as can been
seen from the hereinafter given examples of the invention
vibration isolator, -the changes in spring constant and
hardness due to temperature changes are very small. In
addition, it possesses superior weatherability. Hence,
it is especially suitable for use outdoors where the
fluctuation in temperature is especially great.
~ he microcellular polyurethane elastomer of
this invention can demonstrate its superior effects when
it is integrally formed and foamed on a base that sup-
ports a vibration producing source, for example, a con-
crete block, and thus achieve its intimate adhesion
thereto. Or, it can be separately molded and then be
secured to the vibration producing source by intimately
adhering it to the base~ It thus can be adhered to the
bottom of the base with an adhesive, or a method can be
employed in which a boxlike urethane elastomer product
is molded followed by inserting the b~se in the so molded
'
1~33200
-- 15 _
box.
~ he b~se having a polyurethane elastomer
covering layer, the invention vibration isolator, as
described above, can then be fitted in a recess in the
surface of the floor where the vibration producing source
is to be installed. ~he recess may be formed in advance
in the floor surface, or an alternative procedure is to
install the base having the~polyurethane çlastomer
covering layer on a flat floor surface, after which the
sides of base are packed with concrete or asphalt to form
the recess. Again, it is also possible to lift the
covered base temporarily from the floor surface and pack
the bottom and sides of the base with concrete or asphalt.
Again, it is possible to use a base not having a covering
layer and a recçss provided in advance in the floor
surface and foam and mold the polyurethane elastomer in
the recess by pouring a liquid thereof into the recess.
In this case the polyurethane elastomer is integrally
formed on both the base and the supporting floor surface,
with tlle consequence that a firm adhesion can be obtained.
~ he vibration isolator of the invention can be
used in all areas of industry for the purpose of isolat-
ing vibration or absorption O~sound that accompany vibra-
tion. For example, conceivable applications are that of
installing the invention vioration isolator at the bottom
surface of punch presses for stamping out metals or at
the underside of compressors, or that of isolating the
vibration of air conditioning equipment that has been
L1332~)
,
- 16 -
installed on the floor surface, or using it for isolating
the vibration of subway tracksO
~ he following examples will serve to illustrate
modes of practicing the present invention.
Example 1
Composition o~ liquid A .
Polyether polyol 100 parts by weigh-t .
(a glycerol/propylene
oxide/ethylene oxide
copolymer addition product;
average number of functional
groups = 3~0; number average
molecular weight as shown in
Table 1, below)
Eth~lene glycol As indicated in Table 1
Water 0.35 part by weight .
~oam stabili~.er 0~50 part by weight .:
~sllicone-type surface
active agent (CF 2080, a
product of Toray Silicone
Company)~
~riethylenediamine 0.20 part by weight ``~
Composition of liquo~ B
Polyisocyanate/polyether NC0 Index = 97 ::
polyol prepolymer ~an :
isocyanate terminated per- .
cursory condensation product
of 4,4'-diphenylmethanedi- i~
isocyanate and the above .
polyether polyol; free
NC0 content = 16 wto 5') :.
", . ~,
The liquids A and B Ofthe above compositions
were mlxed with stirring at room temperature, after
which the mixture was poured into a form having the ~. .-
dimensions 200 x 200 x~25 mm and foamed such that its
bulk density would become 008 g/cm3. About onejhour
'
: '
1~33;20C~
-- 17
after the pourin~, the form was removed, and the result-
ing panel-like test specimen was submitted to tests for
its physical propert~es. The results of measurements of
itS p~ysical properties are shown in ~able 1.
~a~ble 1
Run Run Run ~un Physical
No. ~o. No. No. property
1-1 1-2 ~ 1-4 test method
Number average molecular
weight o~ polyether
polyol 3000 4800 6600 9000
Amount used of ethylene
gl~col (wt. part) 2.47 2.29- 2.21 2.16
Ph~sical propert~ test items_
Tensile strength
~ /cm2) 9.6 7.~ 7.5 8.3 (1)
Spring constant
(ton/cm) 1.1 0.83 0.72 0.60 (2)
Permanent compression
set (/0) 36 5O6 8~3 42 (3)
~atigue strength (mm) 2.8 0.52 0.68 3.3 (4)
NotesO-
(1) Measured in accordance with JIS Method K6301.
Dumbbell test pieces are prepared by cutting out the
pieces in parallel to the foaming direction and perpendi-
cular to the skin surface, and the measurement is made at
a pulling speed of 500 mm/min.
(2) 3etqrmined in accordance with JIS Method
K6385. A specimen (100 ~ 100 x 25 mm thick) is precom-
pressed twice at a rate of 1 mm/min in its thickness
1133ZOO
direction. ~he .~lounts of strain at loads of Ool ton
and 0,4 ton are determined from the load-strain curve of
the third compression, and the value of the spring
constant is obtained b~ the following equation.
Spring constant (ton/cm) = -~(o~i-4) r~o l) where
~(0.4) - the amount of strain (cm) at a 0.4 ton load,
and ~(0~ , the amount of strain (cm) at a 0.1 ton load.
(3) Determined in accordance with JIS Method
K6301. A specimen of the dimensions 50 x 50 x 25 mm is
compressed 300/G and left to stand at 70C for 22 hours.
The permanent compression set is then calculated from the
resulting residual strain by the following equation.
t - t
Permanent compression set (/c) = t t2 x 100 where
to~ thickness of test piece before compression; tl:
15 thickness of spacer; and t2: thickness of test piece 30 ~-
minutes after the compression testO
(4) Measured in accordance with SRIS Method 3502~
A specimen of the dimensions 50 x 50 x 25 mm is repeated-
ly compressed 106 times at a frequency of 5Xz and a re-
peated displacement amplitude of 4 mm ~ 2 mm. ~he amount
of fatigue is then measured~
EXample 2
.
- :
~ ` :
`` 1133ZVV
-- 19 --
Com~osition of liquid A
Polyether polyol 100 parts by weight
(average number of func-
tional groups and composi-tion
as indicated in ~able 2, below;
number average molecular
weight = 4800)
Ethylene glycol As indicated in
Table 2, below.
Water 0.35 pa~t by weight
Foam stabilizer 0.50 part by weight
ta silicone-type surface
active agent (CF 2080, a
product of ~oray Silicone
Company)~
Triethylenediamine 0.20 part by weight
Composition of liquid B
Polyisocyanate/polyether NC0 Index = 97
polyol prepolymer (the same as
that used in Example 1)
~he liquids A and 3 of the above compositions
were reacted as in Example 1 to obtain panel test pieces.
The physical properties of these test pieces were
measured, with the results shown in Table 2, below.
1133ZOO
- 20 -
~able 2
Run Run Run
No. 2-1 No. 202 No. 203
.
Average number of functional
groups of the polyether (a) ~b) ~ ~
polyol used 2 3' 4~c,
Amount used of ethylene
glycol (parts by weight) 2.20 2.29 2.39
Ph.ysical propert~Y test items
~ensile strength (kg/cm2) 4.2 8.8 10.2
Spring constant (ton/cm) 0.63 0.83 1. Z
Permanent compression set
(/0) 28 5.6 31
Fatigue strength (mm) 2.2 0.52 2.4
Notes.-
,
(a) Propylene ~lycol/propylene oxide/ethyleneoxide copolymer addition product
(b) Glycerol/propylene oxide/ethylene oxide
copolymer addition product
(c) Pentaerythritol/propylene oxide/eth~lene
oxide copolymer addition product
Example 3
- - --.
.,
1~33200
- 21 -
Com~osition of liquid A
Polyether polyol 100 parts by weight
(a glycerol/propylene oxide/
ethylene oxide copolymer
addition product; average
number of functional groups
= 3.0, number average
molecular weight = 5200)
Ethylene glycol As shown in Table 3
Water 0.35 part by weight
Foam stabilizer (a silicone- 0.50 part by weight
type surface active agent
CF-2080)
~riethylenediamine 0.20 part by weight
Com~osition of liquid :B
Polyisocyanate/polyether NC0 Index = 97
polyol prepolymer (an iso-
cyanate-terminated percusory
condensation product of 4,4'-
diphenylmethanediisocyanate
and the above pol,yether polyol;
free NC0 content - 16 wt. /0~
'rhe liquids A and B of the above compositions
were reacted as in Example 1 to obtain panel test pieces.
~he physical properties of these test pieces are shown in
'rable ~.
~ ~ :
- :
~133ZOO
-- 22
~able 3
Run No. 3-1 Run NoO 3-2 Run No. 3-3
_ _ _ _
Amount used of ethylene 0.83 2.27 23.0
glycol (part by weight)
(Equivalent concentration
of ethylene glycol) (002xlO 3) (0.5x10-3) (2.2x10-3)
Physical property test items
~ensile strength(kg/cm2) 3.2 7.6 18.2
Spring constant (ton/cm) 0.09 0.78 3.21
Permanent compression
set (/0) 37 6.2 45
~atigue strength (mm) 1.5 0.48 2.6
Example 4
Composition of liquid A
Polyether polyol 100 parts by weight
(a glycerol/propylene oxide/
e~thylene oxide copolymer
addition product; average
number of functional groups
= 3.0, number average molecular
weight = 4800)
Ethylene gl~col 2.27 parts by weight
Water 0014-1.2 parts by weight
Foam stabilizer 0O50 part by weight
(a silicone-type surface
active agent CF-2080)
Triethylenediamine 0.20 part by weight
9~
Polyisocyanate/pol ether NC0 Index = 97
polyol prepolymer ~an iso-
cyanate-terminated percursory
condensation product of 4,4'-
diphenylmethanediisocyanate
and the above polyether
polyol; free NC0 conten-t =
16 wt. %)
.
. . . . .
-. ~ ' : ' .
:
1133200
-- 23
The liquids A and B of the above compositions
were reacted as in Example 1 to give panel test pieces
having the bulk densities 0.3 - 0.9. ~he results of
measurement of the spring constants of these test pieces
are shown in ~able 4.
'rable 4
Bulk densitY ~ Spring constant
(~/cm3~ (ton/cm)
o.3 0.1
0.4 0.15
0.5 0.2
0.6 0.35
0.7 0.65
0.8 0.~
0.9 . 1.5
Example 5
rhe liquids A and B of the same composition as
in Run No. 1_2 of Example 1 were used, and a panel having
the dimensions 200 x 200 x 25 mm was prepared by operat-
ing as in Example 1. A test piece measuring 100 x 100 x
25 mm was cut ou-t from the foregoing panel, and its load-
strain relationship was determined by the method
described belowr ~he results are shown in ~able 5, below.
1133Z00
-- 24
~able 5
_t ain ~ Static load (tOI1)
O O
lo 0~18
0.35
o. 54
0.73
0.90
1.22
Measurement of load-strain:
In the same way as in the measurement of the
spring constant, a static compression load is
exerted, and the load-strain is determined
from the resulting load-strain curven
As apparent from ~able 5, the microcellular
polyurethane elastomer of this invention has an elastic
recovery that is practically lO~o up to a strain of 50%.
~he foregoing test piece was also measured for
its changes in spring constant and hardness (measured
with a rubber hardness tester type C manufactured by
Kobunshi Keiki Co~, Ltd., Japan) ascribable to changes
in temperature. ~he results obtained are shown in ~able
6, below.
~- ~
1133ZOo
-- 25 --
~able 6
Spring
~emperature constant Hardness
(C) (ton/_m) (degree)
-50 4.3 72
1 A 1 66
_3o 0071 60
-20 0.70 59
-10 0.68 58
0 0.65 58
+10 0.65 58
+20 0.65 57
+3 0.64 58
~40 0.65 57
+50 0.65 59
+60 0.64 58
+70 0.64 58
E~cample 6
irhe liquids A and B of the same composition as
in Run No. 1-2 of 13xample 1 were used, and a panel having
the dimensions 200 x 200 x 25 mm was prepared. A sample
of 5-mm thickness for use in the tensile test was prepared
from the foregoing panel, and a test piece thereof was
placed in an ozone aging tester (Model OM-2 manufactured
by Suga Shikenki Co., Ltd., Japan) in a 50% elongated
state and was expo sed to an atmo sphere of an ozone con-
centration of 70 pphm for 200 hours to check the state of
crack formation at ~0k elongation. No abnormality was
noted.
, ~ -, :
- . ,. .- : . . , -
1133ZOO
-- 2~. _
In contrast, cracks formed in natural ruhber,
nitrile rubber and chloroprene rubber after respectively
40, 48 and 70 hours.
