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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to low resilience urethane foam having
excellent low resilience useful as an impact energy absorbing material, a
sound insulating material and a vibration damping material. The material
is capable of ensuring a uniform pressure distribution to reduce fatigue
and pressure gangrene, when used as a cushioning material for chairs and
mattresses.
2. Description of the Prior Art
Low resilience urethane foam useful as the impact energy absorbing
material, the sound insulating material, the vibration damping material
and the cushioning material for chairs and mattresses is known. With the
known type of low resilience urethane foam, components of the urethane
foam, namely, type of polyisocyanate, functionality and hydroxyl value of
polyol, are selected and formulated such that glass transition can be
caused at temperature for the urethane foam to be used, i.e., at room
temperature, so that low resilience can be imparted to the urethane foam
by the glass transition phenomenon.
This known type urethane foam, formulated such that the glass transition
can be caused at room temperature, shows excellent low resilience by the
glass transition phenomenon at room temperature, but it has a disadvantage
that at a temperature less than that of occurence of the glass transition,
e.g., at low temperatures of 0.degree. C. or less, the urethane foam
becomes glassy and its hardness increases rather drastically from that at
room temperature.
SUMMARY OF THE INVENTION
It is, therefore, the object of the present invention to provide low
resilience urethane foam having excellent low resilience at room
temperature and being low in increase of hardness even at low temperature.
The present invention provides low resilience urethane foam produced by
reaction of urethane foam compositions comprising polyol (a),
polyisocyanate (b), catalyst (c) and blowing agent (d), characterized in
that the low resilience urethane foam has at least one glass transition
point in each of a temperature range of -70.degree. C. to -20.degree. C.
and a temperature range of 0.degree. C. to 60.degree. C.; and that where
the glass transition point is expressed as a tan .delta. peak obtained
when measurement on dynamic viscoelasticity of the low resilience urethane
foam is performed at a frequency of 10 herz, the tan .delta. peak(s) at
the temperature range of -70.degree. C. to -20.degree. C. is/are 0.15 or
more and the tan .delta. peak(s) at the temperature range of 0.degree. C.
to 60.degree. C. is/are 0.3 or more.
It is preferable that the polyol (a) is at least one polyol selected from
the group consisting of polyoxyalkylene polyol, vinyl polymer-containing
polyoxyalkylene polyol, polyester polyol, and polyoxyalkylene polyester
block copolymer polyol.
Further, it is preferable that the polyol (a) comprises polyol (a-1) of 1.5
to 4.5 in average functionality and 20-70 mgKOH/g in hydroxyl value and
polyol (a-2) of 1.5 to 4.5 in average functionality and 140-300 mgKOH/g in
hydroxyl value and also contains therein the polyol (a-1) ranging from 32
weight percent to 80 weight percent and the polyol (a-2) ranging from 20
weight percent to 68 weight percent.
It is then preferable that the polyol (a-1) comprises polyoxyalkylene
polyol and polyoxyalkylene polyester block copolymer polyol and also
contains therein the polyoxyalkylene polyol and the polyoxyalkylene
polyester block copolymer polyol, with the range from 30 weight percent to
70 weight percent, respectively. It is also preferable that the polyol
(a-2) is polyoxyalkylene polyol in which oxyethylene units of not less
than 20 weight percent, particularly preferable not less than 60 weight
percent, are contained in the oxyalkylene unit.
The polyisocyanate (b) is preferably toluene diisocyanate, and the blowing
agent (d) is preferably water.
Also, it is preferable that a storage modulus (E'), which is obtained
together with the tan .delta. peak when the measurement on the dynamic
viscoelasticity of the low resilience urethane foam is performed at a
frequency of 10 herz, is not more than 5 MPa at temperature of not less
than 0.degree. C., further preferably not more than 5 MPa at temperature
of not less than -20.degree. C.
The low resilience urethane foam of the present invention has an excellent
low resilience of the impact resilience (ball rebound) modulus of not more
than 20% at 25.degree. C. and yet minimizes the tendency to increase the
hardness even at low temperatures. Therefore, even in a low temperature
range, the urethane foam can be effectively used as the impact energy
absorbing material, the sound insulating material, the vibration damping
material and the cushioning material for chairs and mattresses.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a measurement result for viscoelasticity of Example 1;
FIG. 2 shows a measurement result for viscoelasticity of Example 2;
FIG. 3 shows a measurement result for viscoelasticity of Example 3;
FIG. 4 shows a measurement result for viscoelasticity of Example 4;
FIG. 5 shows a measurement result for viscoelasticity of Example 5;
FIG. 6 shows a measurement result for viscoelasticity of Example 6;
FIG. 7 shows a measurement result for viscoelasticity of Example 7;
FIG. 8 shows a measurement result for viscoelasticity of Comparative
Example 1;
FIG. 9 shows a measurement result for viscoelasticity of Comparative
Example 2;
FIG. 10 shows a measurement result for viscoelasticity of Comparative
Example 3;
FIG. 11 shows a measurement result for viscoelasticity of Comparative
Example 4;
FIG. 12 shows a measurement result for viscoelasticity of Comparative
Example 5;
FIG. 13 shows a measurement result for viscoelasticity of Comparative
Example 6;
FIG. 14 shows a measurement result for viscoelasticity of Comparative
Example 7;
FIG. 15 shows a measurement result for viscoelasticity of Comparative
Example 8;
FIG. 16 shows a measurement result for viscoelasticity of Comparative
Example 9;
FIG. 17 shows a measurement result for viscoelasticity of Comparative
Example 10;
FIG. 18 shows a measurement result for viscoelasticity of Comparative
Example 11;
FIG. 19 shows a measurement result for viscoelasticity of Comparative
Example 12;
FIG. 20 shows a measurement result for viscoelasticity of Comparative
Example 13;
FIG. 21 shows a measurement result for viscoelasticity of Comparative
Example 14;
FIG. 22 shows a diagram plotting curves for storage modulus (E') of
Examples 6 and 7 and Comparative Examples 10-14.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Low resilience urethane foam according to the present invention is produced
by reaction of the urethane foam compositions comprising polyol (a),
polyisocyanate (b), catalyst (c) and blowing agent (d).
Polyols for usual use in producing urethane foams may be used as the polyol
(a) used in the present invention. The polyol is properly selected for use
such that the produced urethane foam can have at least one glass
transition point in each of the temperature range of -70.degree. C. to
-20.degree. C. and the temperature range of 0.degree. C. to 60.degree. C.
It is preferable that the polyol (a) is at least one polyol selected from
the group consisting of polyoxyalkylene polyol, vinyl polymer-containing
polyoxyalkylene polyol, polyester polyol, and polyoxyalkylene polyester
block copolymer polyol.
The polyoxyalkylene polyols include those in which alkylene oxides are
added to initiators such as water, alcohol, amine and ammonia. The alcohol
that may be used as the initiator includes monohydric or polyhydric
alcohol including monohydric alcohol such as methanol and ethanol;
dihydric alcohol such as ethylene glycol and propylene glycol; trihydric
alcohol such as glycerin and trimethylolpropane; tetrahydric alcohol such
as pentaerythritol; hexahydric alcohol such as sorbitol; and octahydric
alcohol such as saccharose. The amines that may be used as the initiator
include monofunctional or polyfunctional amines including monofunctional
amines such as dimethylamine and diethylamine; bifunctional amines such as
methylamine and ethylamine; trifunctional amines such as monoethanolamine,
diethanolamine and triethanolamine; tetrafunctional amines such as
ethylenediamine; and pentafunctional amines such as diethylenetriamine. Of
these initiators, monohydric to hexahydric alcohol and monofunctional to
pentafunctional amines may be cited as preferable initiators.
The alkylene oxides that may be used include, for example, ethylene oxide,
propylene oxide, 1,2-, 1,3-, 1,4- and 2,3-butylene oxides and combinations
of two or more thereof. Of these alkylene oxides, propylene oxide and/or
ethylene oxide may be cited as preferences. When used in combination, they
may take either of the block addition and the random addition, preferably
the block addition.
The vinyl polymer-containing polyoxyalkylene polyols that may be used
include those in which vinyl monomers, such as acrylonitrile and styrene,
are polymerized and stably dispersed in the polyoxyalkylene polyol cited
above in the presence of radicals. The content of the vinyl polymer in the
polyoxyalkylene polyol is usually 15 weight percent to 45 weight percent.
The polyester polyols that may be used include those obtained by
condensation polymerization of one or two or more compounds having two or
more hydroxyl groups including, for example, ethylene glycol, diethylene
glycol, triethylene glycol, 1,2-propylene glycol, trimethylene glycol,
1,3- or 1,4-butylene glycol, hexamethylene glycol, decamethylene glycol,
glycerin, trimethylolpropane, pentaerythritol and sorbitol and one or two
or more compounds having two or more carboxyl groups including, for
example, adipic acid, succinic acid, malonic acid, maleic acid, tartaric
acid, pimelic acid, sebacic acid, phthalic acid, terephthalic acid,
isophthalic acid and trimellitic acid; and those obtained by ring opening
polymerization of .epsilon.-caprolactone or the like.
The polyoxyalkylene polyester block copolymer polyols that may be used
include those having the structure of polyoxyalkylene polyol being blocked
by a polyester chain, as disclosed by, for example, JP Patent Publication
No. Sho 48(1973)-10078, or in which the part to be substituted by hydrogen
atoms of hydroxyl groups of the polyoxyalkylene polyol or of the
derivative having hydroxyl groups is expressed by a general formula (1)
given below.
.paren open-st.CO--R.sub.1 --COO--R.sub.2 --O.paren close-st..sub.n H (1)
(Where R.sub.1 and R.sub.2 are bivalent hydrocarbon and n is a number
larger than 1 in average). In the general formula (1), bivalent
hydrocarbon residues expressed by R.sub.1 include, for example, saturated
aliphatic or aromatic polycarboxylic acid residues; bivalent hydrocarbon
residues expressed by R.sub.2 include, for example, residues resulting
from cleavage of compounds having cyclic ether groups; and n is preferably
the number ranging from 1 to 20. The polyoxyalkylene polyester block
copolymer polyols are obtained by allowing polycarboxylic anhydride and
alkylene oxide to react with polyoxyalkylene polyol.
It is preferable that the polyol (a) used in the present invention
comprises polyol (a-1) of 1.5 to 4.5 in average functionality and 20-70
mgKOH/g in hydroxyl value, preferably 30-60 mgKOH/g in hydroxyl value, and
polyol (a-2) of 1.5 to 4.5 in average functionality and 140-300 mgKOH/g in
hydroxyl value, preferably 200-270 mgKOH/g in hydroxyl value. With the
average functionality of less than 1.5, physical properties of the
urethane foam obtained, such as dry heat permanent set (compression set),
sometimes may deteriorate drastically. With the average functionality of
more than 4.5, the urethane foam obtained will have reduced stretchability
and increased hardness and as a result, the physical properties, such as
tensile strength, sometimes may deteriorate. With the polyols comprising
polyol (a-1) of 20-70 mgKOH/g and polyol (a-2) of 140-300 mgKOH/g which
are different in hydroxyl value from each other, the urethane foam
obtained can be given a glass transition point in each of the temperature
range of -70.degree. C. to -20.degree. C. and the temperature range of
0.degree. C. to 60.degree. C. with ease.
Further, it is preferable that the polyol (a) contains therein the polyol
(a-1) in the range of 32-80 weight percent and the polyol (a-2) in the
range of 20-68 weight percent. With the polyol (a-1) of less than 32
weight percent, in other words, with the polyol (a-2) of more than 68
weight percent, the tan .delta. peak of the urethane foam obtained will be
less than 0.15 in the temperature range of -70.degree. C. to -20.degree.
C., so that the hardness at room temperature sometimes may increase. On
the other hand, with the polyol (a-1) of more than 80 weight percent, in
other words, with the polyol (a-2) of less than 20 weight percent, the tan
.delta. peak of the urethane foam obtained will be less than 0.3 in the
temperature range of 0.degree. C. to 60.degree. C., so that the impact
resilience at room temperature sometimes may increase. Further, it is
preferable that the polyol (a) contains therein the polyol (a-1) in the
range of 34-75 weight percent and the polyol (a-2) in the range of 25-66
weight percent.
It is preferable that the polyol (a-1) comprises polyoxyalkylene polyol and
polyoxyalkylene polyester block copolymer polyol. The polyol (a-1)
comprising polyoxyalkylene polyol and polyoxyalkylene polyester block
copolymer polyols enables the impact resilience of the urethane foam
obtained to be reduced. The polyol (a-1) should then preferably contain
therein the polyoxyalkylene polyol and polyoxyalkylene polyester block
copolymer polyol in the range of 30-70 weight percent, respectively, in
the range of which the effect of reducing the impact resiliency is most
produced.
It is preferable that the polyol (a-2) is polyoxyalkylene polyol in which
an oxyethylene unit is contained in the oxyalkylene unit. Where the polyol
(a-2) is polyoxyalkylene polyol in which the oxyethylene unit is contained
in the oxyalkylene unit, the urethane foam obtained can be given the glass
transition point in each of the temperature range of -70.degree. C. to
-20.degree. C. and the temperature range of 0.degree. C. to 60.degree. C.
with further ease. It is then preferable that 20 weight percent or more,
further preferably 60 weight percent or more, of oxyethylene unit is
contained in the oxyalkylene unit. The increase of oxyethylene unit
contained in oxyalkylene unit enables the impact resiliency to be reduced
further.
An interrelation of the molecular weight, the functionality and the
hydroxyl value of the polyol is expressed by the following fomula given
below.
##EQU1##
Known polyisocyanates in usual use for producing the urethane foam may be
used as the polyisocyanate (b) used in the present invention. The
polyisocyanates which may be used include aromatic polyisocyanates such as
2,4- or 2,6-tolylene diisocyanate (TDI), diphenylmethane diisocyanate
(MDI), phenylene diisocyanate (PDI) and naphthalene diisocyanate (NDI);
aromatic aliphatic polyisocyanates such as 1.3- or 1,4-xylylene
diisocyanate (XDI); aliphatic polyisocyanates such as hexamethylene
diisocyanate (HDI); cycloaliphatic polyisocyanates such as
3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI),
4-4'-methylene-bis (cyclohexyl isocyanate) (H.sub.12 MDI), 1,3- or 1,4-bis
(isocyanatomethyl) cyclohexane (H.sub.6 XDI) and modified polyisocyanates
thereof including carbodiimides, biurets, allophanates, dimers, trimers or
polymethylene polyphenyl polyisocyanates (crude MDI, polymeric MDI). These
may be used singly or in combinations of two or more polyisocyanates. Of
these polyisocyanates, the aromatic polyisocyanates are of preferable and
the TDI is of further preferable.
Known catalysts in usual use for producing the urethane foam may be used as
the catalyst (c) used in the present invention. The catalysts that may be
used include (i) amine catalysts including tertiary amines, such as
triethylamine, triethylenediamine and N-methylmorpholine; quaternary
ammonium salts, such as tetraethylhydroxyl ammonium; and imidazoles, such
as imidazole and 2-ethyl-4-methylimidazole and (ii) organic metal
catalysts including organic tin compounds, such as tin acetate, tin
octylate, dibutyltin dilaurate and dibutyltin chloride; organic lead
compounds such as lead octylate and lead naphthenate; and organic nickel
compounds such as nickel naphthenate. Of these catalysts, a combination of
the amine catalyst and the organic metal catalyst is preferable, and
particularly preferable is the combination of the tertiary amine and the
organic tin compound.
Known blowing agents in usual use for producing the urethane foam may be
used as the blowing agent (d) used in the present invention. The blowing
agents that may be used include water and/or halogen substituted aliphatic
hydrocarbon blowing agents such as trichlorofluoromethane,
dichlorodifluoromethane, trichloroethane, trichloroethylene,
tetrachloroethylene, methylene chloride, trichlorotrifluoroethane,
dibromotetrafluoroethane and carbon tetrachloride. These blowing agents
may be used in combinations of two or more, while in the present invention
water is preferably used alone.
The urethane foam compositions of the present invention may include foam
stabilizer, flame retardant and other additives, in addition to the
components mentioned above, if needed. Known foam stabilizers in usual use
for producing the urethane foam, such as siloxane-oxyalkylene block
copolymer, may be used as the foam stabilizer used in the present
invention. An example thereof is F-242T available from Shin-Etsu Chemical
Co., Ltd. Also, known flame retardants in usual use for producing the
urethane foam may be used as the flame retardant used in the present
invention, such as condensed phosphate (an example thereof is CR-504
available from Daihachi Chemical Industry Co., Ltd.) and
trischloroisopropyl phosphate (an example thereof is FYROL PCF available
from Akzo Kashima Limited). Other additives that may be used include, for
example, known colorant, plasticizer, antioxidant and ultravoilet absorber
in usual use for producing the urethane foams.
No particular limitation is imposed on the formulating proportion of the
components of the urethane foam composition including polyol (a),
polyisocyanate (b), catalyst (c) and blowing agent (d), as long as the
components are formulated in such a proportion as to allow the low
resilience urethane foam to be produced by the foaming of the urethane
foam compositions. For example, 0.01-5 parts by weight, preferably 0.2-3
parts by weight, of the catalyst (c); 0.5-4.5 parts by weight, preferably
0.8-3.5 parts by weight, of water; and 0.1-4 parts by weight, preferably
0.4-2.0 parts by weight, of the foam stabilizer (e), if formulated; and
not more than 20 parts by weight, preferably not more than 15 parts by
weight, of the flame retardant, if formulated, are formulated to 100 parts
by weight of the polyol (a). The polyisocyanate (b), when formulated, is
formulated in such a proportion that the isocyanate index can reach e.g.
75-125, preferably 85-115.
To obtain the low resilience urethane foam, the urethane foam compositions
may be foamed in the abovesaid proportion in known foaming methods, such
as a slabbing method, a molding method and a spraying method.
The low resilience urethane foam of the present invention thus obtained has
at least one glass transition point in each of the temperature range of
-70.degree. C. to -20.degree. C., preferably -50.degree. C. to -25.degree.
C., and the temperature range of 0.degree. C. to 60.degree. C., preferably
30.degree. C. to 55.degree. C. It is noted here that "the glass transition
point" used herein indicates the temperature at which the glass transition
of the urethane foam from a glassy state to a rubbery state is caused. In
the present invention, the tan .delta. peak obtained when measurement on
dynamic viscoelasticity is carried out at a frequency of 10 herz is
preferably expressed as the glass transition point.
Where the tan .delta. peak is set as the glass transition point, the low
resilience urethane foam of the present invention has at least one tan
.delta. peak of 0.15 or more, preferably 0.18 or more, in the temperature
range of -70.degree. C. to -20.degree. C. and at least one tan .delta.
peak of 0.3 or more, preferably 0.48 or more, in the temperature range of
0.degree. C. to 60.degree. C. Unless the glass transition point exists in
each of the temperature range of -70.degree. C. to -20.degree. C. and the
temperature range of 0.degree. C. to 60.degree. C. and the tan .delta.
peak of the glass transition point is 0.15 or more in the range of
-70.degree. C. to -20.degree. C. and the tan .delta. peak of the glass
transition point is 0.3 or more in the range of 0.degree. C. to 60.degree.
C., the hardness of the urethane foam will increase at low temperature and
no excellent low resiliency will be produced at room temperature.
It is desirable that the low resilience urethane foam of the present
invention has a given tan .delta. peak(s) in each of the two temperature
ranges described above. Two or more tan .delta. peaks may exist in a
temperature range. The at least one tan .delta. peak in the temperature
range of -70.degree. C. to -20.degree. C. is preferably in the range of
0.15-0.5, and the at least one tan .delta. peak in the temperature range
of 0.degree. C. to 60.degree. C. is preferably in the range of 0.3-1.0.
A storage modulus (E') of the low resilience urethane foam of the present
invention, which is obtained together with the tan .delta. peak when the
measurement on the dynamic viscoelasticity is carried out at the frequency
of 10 herz, is preferably not more than 5 MPa at temperature of not less
than 0.degree. C., further preferably not more than 5 MPa at temperature
of not less than -20.degree. C. The storage modulus (E') of not more than
5 Mpa provides only a small increase in hardness, and the storage modulus
(E') of not more than 5 MPa at not less than 0.degree. C., further at not
less than -20.degree. C. can ensure the use range of the urethane foam
even at lower temperatures and thus enables the urethane foam to be
effectively used even in a cold area.
Further, it is preferable that the storage modulus (E') at -20.degree. C.
is in the range of less than 40%, preferably less than 25%, of the storage
modulus (E') at -100.degree. C. With the storage modulus (E') at
-20.degree. C. is more than 40%, the urethane foam sometimes may become
rigid like a stone.
The low resilience urethane foam of the present invention, usually having a
density of 0.010 g/cm.sup.3 to 0.8 g/cm.sup.3, has an excellent low
resilience of an impact resilience modulus of not more than 20% at
25.degree. C. and yet enables the hardness not to increase so much even at
low temperatures. Therefore, the low resilience urethane foam of the
present invention can be used effectively as the impact energy absorbing
material, the sound insulating material, the vibration damping material
and the cushioning material for chairs and mattresses even in a low
temperature range.
EXAMPLES
With reference to examples and comparative examples, the present invention
directed to low resilience urethane foam will be concretely described
below. It is to be understood, however, that the scope of the present
invention is by no means limited to the illustrated examples.
1) Raw material
The following raw materials were used.
Polyol (a):
(1) Polyoxyalkylene polyester block copolymer polyol, Average functionality
of about 3, and Hydroxyl value of 56 mgKOH/g;
(2) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 34 mgKOH/g, and 100 weight percent oxypropylene content for
oxyalkylene moiety;
(3) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 250 mgKOH/g, 30 weight percent oxypropylene content for
oxyalkylene moiety, and 70 weight percent oxyethylene content for
oxyalkylene moiety;
(4) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 250 mgKOH/g, and 100 weight percent oxypropylene content for
oxyalkylene moiety;
(5) Polyoxyalkylene polyol, Average functionality of about 2, Hydroxyl
value of 105 mgKOH/g, and 100 weight percent oxyethylene content for
oxyalkylene moiety;
(6) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 250 mgKOH/g, 60 weight percent oxypropylene content for
oxyalkylene moiety, and 40 weight percent oxyethylene content for
oxyalkylene moiety;
(7) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 100 mgKOH/g, and 100 weight percent oxypropylene content for
oxyalkylene moiety;
(8) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 250 mgKOH/g, 85 weight percent oxypropylene content for
oxyalkylene moiety, and 15 weight percent oxyethylene content for
oxyalkylene moiety;
(9) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 210 mgKOH/g, 70 weight percent oxypropylene content for
oxyalkylene moiety, and 30 weight percent oxyethylene content for
oxyalkylene moiety;
(10) Polyoxyalkylene polyol, Average functionality of about 3, Hydroxyl
value of 160 mgKOH/g, 85 weight percent oxypropylene content for
oxyalkylene moiety, and 15 weight percent oxyethylene content for
oxyalkylene moiety; and
(11) Polyoxyalkylene polyol, Average functionality of about 4, Hydroxyl
value of 180 mgKOH/g, 70 weight percent oxypropylene content for
oxyalkylene moiety, and 30 weight percent oxyethylene content for
oxyalkylene moiety.
Polyisocyanate (b):
Toluene diisocyanate (a mixture of 2,4-isomer of 80 weight percent and
2,6-isomer of 20 weight percent) (Takenate T-80 available from Takeda
Chemical Industries, Ltd.);
Catalyst (c):
(1) Bis(2-dimethylaminoethyl) ether/dipropylene glycol)(70% solution)
(TOYOCAT ET available from TOSOH CORPORATION);
(2) Bis(2-dimethylaminoethyl) ether/dipropylene glycol)(70% solution) (NIAX
A-1 available from Witco Corporation);
(3) Tin Octylate (STANOCT available from YOSHITOMI FINE CHEMICALS, LTD.)
(4) Tin Octylate (DABCO T-9 available from Air Products and Chemicals,
Inc.)
Blowing agent (d):
Water (Demineralized water)
Foam stabilizer (e):
Siloxane-oxyalkylene block copolymer foam stabilizer (F-242T available from
Shin-Etsu Chemical Co., Ltd.)
Flame retardant (f):
(1) Condensed phosphate ester (CR-504 available from Daihachi Chemical
Industry Co., Ltd.); and
(2) Trischloroisopropyl phosphate (FYROL PCF available from Akzo Kashima
Limited).
2) Production of urethane foams of Examples and Comparative Examples:
Components and proportions of the urethane foam compositions of Examples
1-7 and Comparative Examples 1-14 are shown in TABLES 1 and 2. The
proportions of the components of all the urethane foam compositions shown
in TABLES 1 and 2 are expressed by parts by weight, except for the
isocyanate index.
TABLE 1
Examples
Urethane foam compositions 1 2 3 4 5 6
7
Polyol (a)(1) 40 40 40 -- -- -- --
Polyol (a)(2) 30 30 30 40 35 40
35
Polyol (a)(3) 30 30 -- -- -- -- --
Polyol (a)(4) -- -- -- -- -- -- --
Polyol (a)(5) -- -- -- -- -- -- --
Polyol (a)(6) -- -- 30 -- -- -- --
Polyol (a)(7) -- -- -- -- -- -- --
Polyol (a)(8) -- -- -- -- -- -- --
Polyol (a)(9) -- -- -- 60 65 -- --
Polyol (a)(10) -- -- -- -- -- 15 16.25
Polyol (a)(11) -- -- -- -- -- 45 48.75
Catalyst (c)(1) 0.3 0.3 0.3 0.2 0.3 --
--
Catalyst (c)(2) -- -- -- -- -- 0.3 0.3
Catalyst (c)(3) 0.08 0.08 0.08 0.08 0.08 --
--
Catalyst (c)(4) -- -- -- -- -- 0.1 0.05
Blowing agent (d) Water 1.5 2 1.5 1.5 1.5 1.5
1.5
Foam stabilizer (e) F-242T 1 1 1 1 1 1
1
Flame Retardant (f)(1) 12 12 12 12 12 --
--
Flame Retardant (f)(2) -- -- -- -- -- -- --
Polyisocyanate (b) 31.2 36 31.2 36.2 37.5 32.9
34.0
Isocyanate Index 100 100 100 100 100 100
100
Cream time (sec.) 12 11 13 10 11 10
10
Risetime sec. 125 120 127 115 116 127
126
Density (kg/m.sup.3) 59.0 50.0 59.2 60.1 61.3 49.9
53.9
25% ILD Hardness (kg/314 cm.sup.2) 3.2 5.4 3.6 4.5 22.6
9.6 10.2
Ball Rebound (%) 8 14 11 18 16 9
5
Compression Set % 1.2 4.2 1.8 1.1 1.3 1.2
0.7
Tensile Strength (kg/cm.sup.2) 0.52 0.50 0.60 0.66 0.71 0.85
1.01
Elongation (%) 179 165 160 162 157 165
159
Tear Strength (kg/cm) 0.36 0.35 0.32 0.35 0.52 0.71
0.66
Glass Transition Peak Temp. (.degree. C.) -32 -38 -30 -45 -49 -48 -47
Point 1 tan .delta. peak 0.30 0.20 0.29 0.30 0.16
0.22 0.16
Glass Transition Peak Temp. (.degree. C.) 36 52 34 42
38 32 33
Point 2 tan .delta. peak 0.52 0.50 0.50 0.51 0.9
0.65 0.72
tan .delta. peak at 25.degree. C. 0.32 0.21 0.37 0.21 0.16
0.40 0.45
E'(-100.degree. C.)(MPa) 24 20 24 40 20 24 25
E'(-20.degree. C.)(MPa) 2.1 3.1 3.5 3 5 2.5 5.8
E'(-20.degree. C.)/E'(-100.degree. C.) .times. 100(%) 8.8 15.5 14.6
7.5 25 10.4 23.2
E'(25.degree. C.)(MPa) 0.26 0.7 0.3 0.6 2.0 0.6
0.9
TABLE 2
Urethane foam Comparative Examples
compositions 1 2 3 4 5 6
7 8 9 10 11 12 13
14
Polyol (a)(1) 30 30 30 40 -- 40
-- -- -- -- -- -- -- --
Polyol (a)(2) -- -- -- 30 -- 30 20 85
30 100 75 50 30 0
Polyol (a)(3) -- -- -- -- -- -- -- -- -- --
-- -- -- --
Polyol (a)(4) 60 60 60 30 -- -- --
-- -- -- -- -- -- --
Polyol (a)(5) 10 10 10 -- -- -- -- --
-- -- -- -- -- --
Polyol (a)(6) -- -- -- -- 30 -- -- -- --
-- -- -- -- --
Polyol (a)(7) -- -- -- -- 70 -- -- -- --
-- -- -- -- --
Polyol (a)(8) -- -- -- -- -- 30 -- -- --
-- -- -- --
Polyol (a)(9) -- -- -- -- -- -- 80 15
70 -- -- -- -- --
Polyol (a)(10) -- -- -- -- -- -- -- -- -- --
6.25 12.5 17.5 25
Polyol (a)(11) -- -- -- -- -- -- -- -- -- --
18.75 37.5 52.5 75
Catalyst (c)(1) 0.2 0.2 0.2 0.25 0.3 0.3
0.3 0.3 0.3 -- -- -- -- --
Catalyst (c)(2) -- -- -- -- -- -- -- -- -- 0.3
0.3 0.3 0.3 0.3
Catalyst (c)(3) 0.02 0.02 0.02 0.06 0.08
0.08 0.08 0.08 0.08 -- -- -- -- --
Catalyst (c)(4) -- -- -- -- -- -- -- -- -- 0.2
0.5 0.1 0.05 0.1
Blowing agent (d) 1.8 1.8 1.8 3 1.5 1.5
1.5 1.5 1.5 1.5 1.5 1.5
1.5 1.5
Water
Foam stabilizer (e) 1 1 1 1 1 1
1 1 1 1 1 1 1
1
F-242T
Flame Retardant -- -- -- 12 12 12 12
12 12 -- -- -- -- --
(f)(1)
Flame Retardant 3 3 3 -- -- -- -- --
-- -- -- -- -- --
(f)(2)
Polyisocyanate (b) 40.4 42.6 44.9 45.7 37.0
31.2 41.6 23.9 38.9 19.8 25.3 30.7
35.1 41.7
Isocyanate Index 90 95 100 100 100 100
100 100 100 100 100 100
100 100
Cream time sec. 14 13 12 12 11 14
12 14 12 11 10 10 10
10
Rise time (sec.) 189 177 155 196 130 131
122 152 120 140 99 120
127 73
Density (kg/m.sup.3) 44.5 44.2 44.3 39.9 55.6
59.4 63.2 55.5 63.1 67.6 52.0 51.5
50.4 56.4
25% ILD Hardness 3.6 7.6 24.4 15.2 3.1
12.2 38.1 4.2 41.2 5.1 5.2 6.1
12.6 20.2
(kg/314 cm.sup.2)
Ball Rebound (%) 2 4 6 13 24 13
18 45 16 38 18 12 4
3
Compression Set (%) 0.4 0.3 0.2 5.3 6.7 3.4
1.9 7.2 1.4 9.4 4.5 2.6
0.7 0.4
Tensile Strength 0.33 0.62 1.09 1.12 0.62
0.82 1.04 0.66 0.82 0.51 0.62 0.81
1.10 1.21
(kg/cm.sup.2)
Elongation (%) 180 170 168 155 172 162
162 158 158 180 178 178
171 162
Tear Strength 0.31 0.57 1.07 0.66 0.36
0.82 0.92 0.38 0.73 0.46 0.49 0.53
0.65 0.72
(kg/cm)
Glass Peak 32 36 40 26 3
23 -45 -50 -50 -44 -40 -40 -50 --
Transition Temp.
Point 1 (.degree. C.)
tan .delta. 0.90 0.92 0.90 0.31 0.76
0.3 0.08 0.88 0.12 0.85 0.70 0.40
0.11 --
peak
Glass Peak -- -- -- -- -- -- 41 56
38 -- -- 43 30 30
Transition Temp.
Point 2 (.degree. C.)
tan .delta. -- -- -- -- -- -- 0.69 0.09
1.0 -- -- 0.26 0.9 0.98
peak
tan .delta. peak at 25.degree. C. 0.80 0.50 0.30 0.31
0.12 0.30 0.46 0.07 0.2 0.11 0.16
0.20 0.60 0.85
E'(-100.degree. C.)(MPa) 26 27 18 10 22
24 25 22 26 47 28 17
21 28
E'(-20.degree. C.)(MPa) 18 20 12 4.0 16
10 13 0.7 10 0.27 0.23 0.37
7.6 20
E'(-20.degree. C.)/E' 69.2 74.0 66.7 40.0 73.7
41.7 52 3.2 38.5 0.57 0.82 2.2
36 71
(-100.degree. C.) .times. 100(%)
E'(25.degree. C.)(MPa) 0.70 2.3 3.3 0.33 0.5
0.71 2.1 0.3 14.1 0.14 0.045 0.075
0.6 0.85
Except for the catalyst (c)(3) or the catalyst (c)(4) and polyisocyanate
(b), the compounds of Examples and Comparative Examples shown in TABLES 1
and 2 were all mixed with a hand mixer and the catalyst (c)(3) or the
catalyst (c)(4) was then added thereto and stirred for 5 seconds.
Immediately thereafter, the polyisocyanate (b) was added to and mixed in
the mixtures in accordance with the isocyanate indexes shown in TABLES 1
and 2. The resultant mixtures were poured into foam boxes to be foamed and
cured. The urethane foams thus produced were allowed to stand for one day
at room temperature and thereafter their physical properties were
measured.
3) Methods of measurement on the physical properties:
Measurements on the physical properties of the obtained urethane foams of
Examples and Comparative Examples were performed in accordance with the
methods below. The results are shown in TABLES 1 and 2.
(a) Measurements on Density, Ball rebound, and Hardness (25% ILD) were
measured in accordance with JIS (Japanese Industrial Standard) K 6401.
(b) Measurements on Compression set (Residual set after compression to 50%
of the thickness at 70.degree. C. for 22 hours) were performed in
accordance with JIS K 6382.
(c) Measurements on Tensile strength and Elongation were performed in
accordance with JIS K 6402.
(d) Measurements on Tear strength were performed in accordance with JIS K
6767.
(e) Dynamic viscoelasticity tests were performed using rectangular
parallelopiped specimens of a length of 2.0 cm and a section of
2.0.times.1.0 cm and the measurements thereon were performed by use of
VISCO ELASTIC SPECTROMETER (VES-F-III, Iwamoto Seisakusho Co., Ltd.) with
a temperature elevation rate of 3.degree. C./min., a frequency of 10 herz
and a vibration amplitude of .+-.0.01 mm. The tan .delta. peak, the
storage modulus (E') and others were determined from the obtained data.
Evaluation on the hardness of Examples 6 and 7 and Comparative Examples
10-14 was made by contact finger at every 10.degree. C. in the range from
-50.degree. C. to 20.degree. C. The results are shown in TABLE 3. In TABLE
3, "S", "H" and "F" indicate "Stone-like rigid", "High load bearing
flexible" and "Flexible", respectively.
TABLE 3
Examples
Comparative Temperature (.degree. C.)
Examples -50 -40 -30 -20 -10 0 10 20
Compar. Ex. 10 S F F F F F F F
Compar. Ex. 11 S F F F F F F F
Compar. Ex. 12 S H F F F F F F
Example 6 S H H F F F F F
Example 7 S S S S S H H F
Compar. Ex. 13 S S S S S S H F
Compar. Ex. 14 S S S S S S S H
4) Measurement results:
Measurement results on the viscoelasticity of the urethane foams of
Examples 1-7 and Comparative Examples 1-14 are shown in FIGS. 1-21,
respectively. Of these figures, for example FIG. 1, representing the
measurement result on the viscoelasticity of the urethane foam of Example
1, shows the tan .delta. curve having two peaks of 0.30 and 0.52 at
-32.degree. C. and 36.degree. C., respectively, and the storage modulus
(E') curve, obtained together with the tan .delta. curve, in which the
glass transition range drops sharply from around -50.degree. C. to around
-30.degree. C.; then drops mildly from around -30.degree. C. to around
0.degree. C. for a while; and then drops again sharply from around
0.degree. C. to around 40.degree. C. into the rubbery range.
On the other hand, FIG. 8, representing the measurement result on the
viscoelasticity of the urethane foam of Comparative Example 1, shows the
tan .delta. curve having a peak of 0.90 at 32.degree. C. and the storage
modulus (E') curve, obtained together with the tan .delta. curve, in which
the glass transition range drops sharply from around -10.degree. C.,
around which the urethane foam was in the glassy state, to around
40.degree. C., into the rubbery range.
Comparative Example 1, which is a general type low resilience urethane
foam, showed a low ball rebound and excellent low resiliency at room
temperature, as is apparent from TABLE 2. However, the urethane foam
became glassy and had drastically increased hardness at low temperatures
of 0.degree. C. or less, as is apparent from FIG. 8. This is clearly seen
from the values of E' at -20.degree. C. shown in TABLE 2. Comparative
Examples 2 and 3 also, in which the isocyanate index of Comparative
Example 1 was varied, had only one tan .delta. peak at temperatures
exceeding 0.degree. C., and their hardness drastically increased at low
temperatures of 0.degree. C. or less, as seen from the values of E' at
-20.degree. C. as well.
In contrast to these, Example 1 showed a low ball rebound and an excellent
low resiliency, as is apparent from TABLE 1, and its hardness did not
increase so much in the temperature range from around 0.degree. C. to
around -30.degree. C. Also, Example 1 did not come into a complete glassy
state until around -50.degree. C. This is clearly seen from the values of
E' at -20.degree. C. shown in TABLE 1.
Example 2, in which parts by weight of water of Example 1 was varied,
showed a low ball rebound at room temperature, as seen from TABLE 1, and
its hardness did not increase so much at temperatures of 0.degree. C. or
less, as seen from the values of E' at -20.degree. C. in TABLE 1.
Example 3, in which the polyoxyethylene content of Example 1 was varied
from 70 weight percent to 40 weight percent, showed a low ball rebound at
room temperature in TABLE 1, and its hardness did not increase so much at
low temperatures of 0.degree. C. or less, as seen from the values of E' at
-20.degree. C. in TABLE 1. Example 3 showed slightly higher ball rebound
and value of E' at -20.degree. C., as compared with Example 1.
Further, Examples 4 and 5, in which the polyol (a) of Example 1 was varied
from the combination of polyoxyalkylene polyester block copolymer polyol
and polyoxyalkylene polyol to the polyoxyalkylene polyol only (the
polyoxyethylene content also was varied from 70 weight percent to 30
weight percent), showed a low ball rebound at room temperature in TABLE 1,
and their hardness did not increase so much at low temperatures of
0.degree. C. or less, as is apparent from the values of E' at -20.degree.
C. in TABLE 1. Examples 4 and 5 showed slightly higher ball rebound and
value of E' at -20.degree. C., as compared with Example 1.
Comparative Examples 4 and 6, in which the ethylene oxide content of the
polyol (a) of Example 1 | | |
