Title of Invention

HARD POLYURETHANE FOAM COMPOSITION AND HEAT INSULATOR FOR KEEPING COOLNESS

Abstract Disclosed herein are environmentally friendly polyurethane foam compositions which are superior in flame resistancy and mechanical properties, and a heat insulator using the same. The hard polyurethane foam composition, comprising a polymeric 4,4'-diphenylmethane diisocyanate; a polyol mixture comprising (a) 20-60 wt% of polyetherpolyol, polymerized by the addition of propylene oxide and ethylene oxide to sorbitol: (b) 10-40 wt% of polyetherpolyol, polymerized by addition of propylene oxide and ethylene oxide to pentaerythritol: (c) 10-20 wt% of polyetherpolyol, polymerized by the addition of propylene oxide and ethylene oxide to sucrose: (d) 10-20 wt% of polyesterpolyol, polymerized by the addition of propylene oxide and ethylene oxide to phthalic anhydride: and (e) 1-20 wt% of polyetherpolyol, polymerized by the addition of ethylene oxide and propylene oxide to brome-substituted glycerine, the NCO/OH ratio of the composition being in the range of 1.0-2.0; and a hydrofluorocarbon lineage foaming agent selected from the group consisting of 1,3-pentafluorobutane, 1, 3-pentafluoropropane and mixtures thereof.
Full Text HARD POLYURETHANE FOAM COMPOSITION AND INSULATOR FOR KEEPING
COOLNESS USING IT
TECHNICAL FIELD
The present invention relates to a hard polyurethane
foam composition which can be prepared into an insulator in
the presence of a hydrofluorocarbon (HFC) foaming agent
which is not harmful to the ozone layer, in addition to
being superior in heat insulation and mechanical properties,
and an insulator using the same.
BACKGROUND ART
Generally, hard urethane foam is prepared from
diisocyanate and polyol in the presence of a foaming agent
such as water, chlorofluorocarbon, hydrochlorofluorocarbon,
hydrofluorocarbon, carbon dioxide, cyclopentane, etc.
Widely used are toluene diisocyanate (TDI) and 4,4-
diphenylmethanediisocyanate. Preferable is polymeric 4,4-
diphenylmethanediisocyanate with an average functional group
number of 2.7 or more.
As for the polyol, it is of polyether or polyester.
Polyetherpolyols are particularly widely used because they
are easy to handle due to their low viscosity and stable to

hydrolysis in addition to being inexpensive.
Polyesterpolyols are superior in heat stability and tensile
strength, but show low hydrolysis resistance. More than
90 % of polyurethane products are prepared from
polyetherpolyols, while polyetherpolyols are used for
special uses.
Physical properties of hard polyurethane foam can be
expressed in a function of density. As the density of hard
polyurethane foam decreases, the thermal conductivity
becomes low, so that its adiabatic performance is improved.
However, physical properties, such as compression strength,
are deteriorated. Thus, it is very difficult to develop
hard polyurethane foam superior in heat insulation and
physical properties, but both of the properties are
necessary to ultra-low temperature insulators or ultra-low
temperature pipe covers for liquefied natural gas storage
tanks and to heat insulators for general uses.
In order to improve the physical properties of
polyurethane foam, the density of polyurethane foam is
increased or a filler, such as glass fiber or carbon fiber,
is used. However, the increase in density and the use of
filler both suffer from the disadvantages of increasing the
thermal conductivity to lower the heat insulation.
Where polyurethane foam is used as an untra low
temperature insulators, a decrease in heat insulation bears

highly negative results. Therefore, there is needed an
improvement in physical properties without a decrease in
heat insulation.
Examples of the foaming agent useful for the
preparation of polyurethane foam include water, carboxylic
acids, fluorocarbon foaming agents, carboxylic acid, and air.
Formerly, chlorofluorocarbon was widely used because
of its low thermal conductivity and high stability in the
air. However, as chlorofluorocarbon was found to harm the
environment, hydrochlorofluorocarbon, cyclohexane, water,
hydrochlorofluorocarbon, or hydrofluorocarbon has been
recently used instead. Particularly regarded as the next
generation foaming agent, hydrofluorocarbon has attracted a
lot of attention because it does not harm the ozone layer,
shows low thermal conductivity and does not diffuse from the
polyurethane foam to the air so as to make the heat
insulation performance to last long.
As substitutes for CPC-11 and CFC-12, HFC-365mfc (1,3-
pentafluorobutane) and HFC-245fa (1,3-pentachloropropane),
found to be not harmful to the ozone layer, have been under
study and used, in addition to HCFC-122 (2,2-dichloro-l,1,1-
trifluoroethane), HCFC-141b (1,1-dichloro-l-fluoroethane),
HFC-134a (1,1,1,2-tetrafluoroethane), and HFC-152a (1,1-
difluoroethane).
Besides foaming agents, various additives such as

catalysts, flame retardants, chain extenders, etc. are used
to prepare polyurethane foam.
Exemplified by low molecular weight diol or diamine, a
chain extender or a crosslinking agent is used with the aim
of increasing the mechanical strength of polyurethane foam.
Tins and amines are useful as catalysts.
The low flame retardancy of polyurethane requires the
use of flame retardants, which are usually halogen,
phosphorus, and inorganic compounds, being grouped into
reactive and additive types.
When the cells formed during foaming are small and
uniform, the resultant foam is improved in heat insulation
and mechanical properties. To this end, silicon surfactants
are used as cell stabilizers.
DISCLOSURE OF THE INVENTION
With the background in mind, the intensive and
thorough research into a heat insulator which is
environmentally friendly as well as exhibiting superior
mechanical and heat insulating properties, conducted by the
present inventors, resulted in the finding that a mixture of
three polyether polyols and one polyester polyol, each
ranging in OH values, from 200 to 659, can be reacted with
polymeric 4,4-dimethylmethanediisocyanate in the presence of

an HFC lineage foaming agent which does not harm the ozone
layer to give a foam with excellent mechanical and heat
insulating properties.
Therefore, it is an object of the present invention to
provide an environmentally friendly polyurethane foam
composition.
It is another object of the present invention to
provide a polyurethane foam composition which shows
excellent mechanical and heat insulating properties.
It is a further object of the present invention to
provide a heat insulator which is environmentally friendly
in addition to being superior in mechanical and heat
insulating properties.
In accordance with the present invention, the above
objects could be accomplished by a provision of a hard
polyurethane foam composition, comprising a polymeric 4,4'-
diphenylmethane diisocyanate; a polyol mixture comprising
(a) 20-60 wt% of polyetherpolyol, polymerized by the
addition of propylene oxide and ethylene oxide to sorbitol:
(b) 10-40 wt% of polyetherpolyol, polymerized by addition of
propylene oxide and ethylene oxide to pentaerythritol: (c)
10-20 wt% of polyetherpolyol, polymerized by the addition of
propylene oxide and ethylene oxide to sucrose: (d) 10-20 wt%
of polyesterpolyol, polymerized by the addition of propylene
oxide and ethylene oxide to phthalic anhydride: and (e) 1-20

wt% of polyetherpolyol, polymerized by the addition of
ethylene oxide and propylene oxide to brome-substituted
glycerine, the NCO/OH ratio of the composition being in the
range of 1.0-2.0; and a hydrofluorocarbon lineage foaming
agent selected from the group consisting of 1,3-
pentafluorobutane, 1,3-pentafluoropropane and mixtures
thereof.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is an electron microscope photograph showing
the micro structure of the hard polyurethane foam prepared
by use of HFC-365mfc as a foaming agent in accordance with
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, polyurethane foam is
prepared from 4,4'-diphenylmethane diisocyanate (MDI) and a
mixture of polyols in the presence of a foaming agent.
The polyol mixture useful in the present invention
comprises (a) 20-60 wt% of polyetherpolyol, polymerized by
the addition of propylene oxide and ethylene oxide to
sorbitol, (b) 10-40 wt% of polyetherpolyol, polymerized by
addition of propylene oxide and ethylene oxide to

pentaerythritol, (c) 10-20 wt% of polyetherpolyol,
polymerized by the addition of propylene oxide and ethylene
oxide to sucrose, (d) 10-20 wt% of polyesterpolyol,
polymerized by the addition of propylene oxide and ethylene
oxide to phthalic anhydride, and (e) 1-20 wt% of
polyetherpolyol, polymerized by the addition of ethylene
oxide and propylene oxide to brome-substituted glycerine.
The polyol mixture ranges from 380 to 510, in average OH
values.
Preferably, the NCO/OH ratio of the composition
comprising polymeric 4,4'-diphenylmethane diisocyanate and
the polyol mixture is in the range of 1.0-2.0.
As described, the polyols used in the present
invention are synthesized from glycerine, pentaerythritol,
sorbitol, and sucrose. Because these alcohols have three,
four, six and eight functional groups, respectively, which
are reactive to the diisocyanate, linear or crosslinking
linkages are formed upon reaction between the reactants.
According to the alcohol bases used, large differences are
found in the resultant polyurethane foams. For example, the
difference in compression strength between the polyurethane
foams based on glycerine and sorbitol is 10 % or upward. In
the present invention, the content of each polyol is
optimized in sufficient consideration of the reaction time,
viscosity and physical properties of the products. The use

of brome-substituted polyol resides with an improvement in
flame retardancy. As for a heat insulator with a low
density, it is poor in flame retardancy. Thus, the brome-
substituted polyol contributes to the improvement of flame
retardancy.
In addition to the diisocyanate and the polyols, the
polyurethane foam composition of the present invention
comprises a foaming agent, a catalyst, and other additives.
A useful foaming agent is selected from among HFC-
365mfc (1,3-pentafluorobutane) and HFC-245fa (1,3-
pentafluoropropane). HFC-365mfc and HFC245fa may be used in
combination without, deteriorating the physical properties of
the polyurethane foam. Therefore, HFC-245fa may be mixed in
the proportions of 0-100% with HFC-365mfc. Water, if
necessary, may be used as a subsidiary foaming agent. It is
preferred that the organic foaming agent is used in the
amount of 3-35 parts by weight based on 100 parts by weight
of the polyols used. Water is preferably added in the
amount of 0-7 parts by weight based on 100 parts by weight
of the polyols used. In this case, the polyurethane foam
obtained has a density of 30-140 kg/m3. The density can be
adjusted to be below 30 kg/m3 or over 14 0 kg/m3 by
controlling the amount of the foaming agent.
Low evaporation temperatures of HFC-365mfc and HFC-
245fa make it easy to prepare polyurethane foam.

Additionally, their low thermal conductivity contributes to
the formation of high heat insulating properties in
polyurethane foam.
Water, used as a subsidiary foaming agent, reacts with
diisocyanate to form urea and discharge carbon dioxide which
is then utilized in the bubbling of the polyurethane foam.
In addition, the reaction heat produced upon reaction
between water and diisocyanate is used for the evaporation
of HFC-365mfc and HFC-245fa. If the amount of water is over
7 parts by weight based on 100 parts by weight of the
polyols used, not only is excessive heat generated by the
reaction to scorch in the polyurethane foam obtained, but
also excess carbon dioxide is present in the polyurethane
foam, giving rise to an increase in thermal conductivity.
In accordance with the present invention, hard
polyurethane foam is prepared from the diisocyanate and the
polyol mixture in the presence of a catalyst with the aid of
a foaming agent, a bubble stabilizer and other additives.
Useful to promote the reaction of the diisocyanate
with the polyols are amine catalysts. In accordance with
the present invention, the catalyst is selected from the
group consisting of pentamethyldiethylene triamine,
dimethylcycloamine, tris(3-
dimethylamino)propylhexahydrotriamine, and mixtures thereof.
The catalyst is preferably used in the amount of 0.1-2.0

parts by weight based on 100 parts by weight of the polyol
mixture used. For example, when too little of a catalyst is
used, the reaction rate becomes so slow as to produce
incomplete hard polyurethane foam which is poor in physical
properties. On the other hand, if the amount of the
catalyst exceeds 2.0 parts by weight, the reaction rate and
physical properties are not improved to the same degree.
The silicon surfactant polysiloxane ether is useful as
a bubble stabilizer in the present invention. The foaming
agent is vaporized by the heat generated during the reaction
between diisocyanate and polyol, forming bubbles to foam the
polyurethane reactants. When the bubbles gather together
into larger ones due to their internal pressures, the
polyurethane foam has poor heat insulating properties and
weak mechanical strength. The silicon surfactant provides
charges on the surface of the bubbles so that the bubbles
become repulsive to each other by the electrostaticity. As
a result, the polyurethane foam retains small and uniform
cells. Preferably, the amount of the bubble stabilizer
falls into the range of 0-2.0 parts by weight based on 100
parts by weight of the polyols used. If the bubble
stabilizer is used in an amount larger than 2.0 parts by
weight, the polyurethane foam becomes poor in compression
strength and load resistance.
To provide the polyurethane foam with flame retardancy,

a flame retardant may be added. Useful are phosphorus flame
retardants, exemplified by tricresyl phosphate. The amount
of the flame retardant preferably ranges from 5 to 15 parts
by weight based on 100 parts by weight of the polyols used.
For example, if the flame retardant is used in an amount
smaller than 5 parts by weight, satisfactory flame
retardancy is not obtained. On the other hand, if the
amount of the flame retardant is over 15 parts by weight,
there is only a slight increase in flame retardancy obtained
and the productivity becomes low.
In accordance with the present invention, a
crosslinking agent may be used to reinforce the strength of
the polyurethane foam, as well as shortening the curing time.
Optionally, other additives which are used in urethane
chemistry, such as fillers, stabilizers, e.g., anti-oxidants
and UV light absorbers, and colorants, etc. may be added.
The polyurethane foam may be prepared in various
methods, such as a one-shot method, a prepolymer method, etc.
According to the one-shot method, all reactants including
isocyanate and polyol are simultaneously fed to a reaction
tank. The one-shot method is simple and easy, but suffers
from the disadvantage of finding difficulty in controlling
reaction rates and producing a large quantity of reaction
heat to cause cracks in the foam. On the other hand,
isocyanate is partially reacted with polyol in advance and

the remaining reactants are added to the prepolymers
synthesized according to the prepolymer method. This method
enjoys the advantage of showing high reaction rates as the
reactants relatively slowly reacted and of allowing the foam
to fill every nook and corner of complicate structures as
the viscosity of the foam is slowly increased. However, the
prepolymer method is disadvantageous in that the production
procedure is so lengthy as to increase the production cost.
In the present invention, the one-shot method is adopted in
consideration of productivity, workability, and production
cost. However, the addition of polyols and additives are
under control lest scorch and cracks attributed to a large
reaction heat are caused.
High or low pressure foaming machines as usually used
in the polyurethane industry may be used.
A better understanding of the present invention may be
obtained in light of the following examples which are set
forth to illustrate, but are not to be construed to limit
the present invention.
EXAMPLE 1
To a polyol mixture comprising 35.0 g of the polyol
polymerized by the addition of propylene oxide and ethylene

oxide to pentaerythritol, 25.0 g of the polyol polymerized
by the addition of propylene oxide and ethylene oxide to
sucrose, 10.0 g of the polyol polymerized by the addition of
propylene oxide and ethylene oxide to phthalic anhydride,
30.0 g of the polyol polymerized by the addition of
propylene oxide and ethylene oxide to sorbitol, and 30.0 g
of the polyol polymerized by the addition of propylene oxide
and ethylene oxide to glycerine, 2.0 g of polysiloxane ether,
a catalyst mixture comprising 0.3 g of
pentamethyldiethylenetriamine, 0.8 g of dimethylcycloamine,
and 0.3 g of tris(3-dimethylamino)propylhexahydrotriamine, a
flame-retardant mixture comprising 10.0 g of tricresyl
phosphate and 0.4 g of water, and 8.0 g of HFC-365mfc were
added to form a resin solution. 140.0 g of 4,4-
dimethylmethanediisocyanate was mixed with the resin
solution to prepare polyurethane foam.
The polyurethane foam was measured for physical
properties and the results and test methods are given in
Table 1, below.



The closed cell content has an influence on the
thermal conductivity, vapor transmittance, and water
absorption. Accordingly, the closed cell content may be
used as a barometer for controlling the quality of
polyurethane foam. The polyurethane foam of this example is
found to be high in the closed cell content as compared with
the usual polyurethane foam which has a closed cell content
of 90 %.
The microstructure of the polyurethane foam prepared
in the example was observed with the aid of an electron
microscope. The foam is based on the cells produced by the
bubbling of the polymer. As seen in Fig. 1, the
polyurethane foam of the present invention contains small
and uniform cells.
EXAMPLE 2
To a polyol mixture comprising 25.0 g of the polyol
polymerized by the addition of propylene oxide and ethylene

oxide to pentaerythritol, 45.0 g of the polyol polymerized
by the addition of propylene oxide and ethylene oxide to
sucrose, 13.0 g of the polyol polymerized by the addition of
propylene oxide and ethylene oxide to glycerine, 14.0 g of
the polyol polymerized by the addition of propylene oxide
and ethylene oxide to phthalic anhydride, and 4 g of the
polyol polymerized by the addition of propylene oxide and
ethylene oxide to brome-substituted glycerine, 2.0 g of
polysiloxane ether, a catalyst mixture comprising 0.4 g of
pentamethyldiethylenetriamine and 0.8 g of
dimethylcyclohexylamine, a flame-retardant mixture
comprising 3.0 g of tricresyl phosphate and 1.1 g of water,
and 26.5 g of HFC-365mfc were added to form a resin solution.
160.0 g of 4,4-dimethylmethanediisocyanate was mixed with
the resin solution to prepare a hard polyurethane foam.
The polyurethane foam was measured for physical
properties and the results and test methods are given in
Table 2, below.



EXAMPLE 3
Hard polyurethane foam was prepared in a manner
similar to that of Example 2, except that 22.0 g of HFC-
245fa was used instead of HFC-365mfc. After its surface was
removed, the hard polyurethane foam was measured for
physical properties, and the results are given in Table 3,
below.



In the presence of hydrofluorocarbon compounds which
are not harmful to the ozone layer, as described
hereinbefore, hard polyurethane foam is obtained which is
superior in mechanical strength while retaining excellent
heat insulating properties. Therefore, using the
polyurethane foam composition of the present invention, an
environmentally friendly heat insulator which exhibits heat
insulation and mechanical properties can be prepared in a
conventional method.
The present invention has been described in an
illustrative manner, and it is to be understood that the
terminology used is intended to be in the nature of
description rather than of limitation. Many modifications
and variations of the present invention are possible in
light of the above teachings. Therefore, it is to be
understood that within the scope of the appended claims, the
invention may be practiced otherwise than as specifically
described.

1. A hard polyurethane foam composition, comprising:
a polymeric 4,4'-diphenylmethane diisocyanate;
a polyol mixture comprising
(a) 20-60 wt% of polyetherpolyol, polymerized by the
addition of propylene oxide and ethylene oxide to
sorbitol:
(b) 10-40 wt% of polyetherpolyol, polymerized by
addition of propylene oxide and ethylene oxide to
pentaerythritol:
(c) 10-20 wt% of polyetherpolyol, polymerized by the
addition of propylene oxide and ethylene oxide to
sucrose:
(d) 10-20 wt% of polyesterpolyol, polymerized by the
addition of propylene oxide and ethylene oxide to
phthalic anhydride: and
(e) 1-20 wt% of polyetherpolyol, polymerized by the
addition of ethylene oxide and propylene oxide to
brome-substituted glycerine, the NCO/OH ratio of
the composition being in the range of 1.0-2.0; and
a hydrofluorocarbon lineage foaming agent selected
from the group consisting of 1,3-pentafluorobutane,
1,3-pentafluoropropane and mixtures thereof.

2. The hard polyurethane foam composition as defined
in claim 1, wherein the composition ranges, in average OH
values, from 380 to 510 and, in average NCO%, from 29 to 32.
3. The hard polyurethane foam composition as defined
in claim 1, wherein the hydrofluorocarbon lineage foaming
agent is used in the amount of 3-35 parts by weight based on
100 parts by weight of the polyol mixture.
4. The hard polyurethane foam composition as defined
in one of claims 1 to 3, further comprising a phosphorus
flame retardant in the amount of 5-30 parts by weight based
on 100 parts by weight of the polyol mixture.
5. The hard polyurethane foam composition as defined
in one of claims 1 to 3, further comprising an amine
catalyst in the amount of 0.1-2.0 parts by weight based on
100 parts by weight of the polyol mixture.
6. The hard polyurethane foam composition as defined
in one of claims 1 to 3, further comprising polysiloxane in
the amount of 0-2.0 parts by weight based on 100 parts by
weight of the polyol mixture.
7. The hard polyurethane foam composition as defined

in claim 3, further comprising water as a subsidiary foaming
agent.
8. A heat insulator, prepared from the urethane foam
composition of claim 1.

Disclosed herein are environmentally friendly
polyurethane foam compositions which are superior in flame
resistancy and mechanical properties, and a heat insulator
using the same. The hard polyurethane foam composition,
comprising a polymeric 4,4'-diphenylmethane diisocyanate; a
polyol mixture comprising (a) 20-60 wt% of polyetherpolyol,
polymerized by the addition of propylene oxide and ethylene
oxide to sorbitol: (b) 10-40 wt% of polyetherpolyol,
polymerized by addition of propylene oxide and ethylene
oxide to pentaerythritol: (c) 10-20 wt% of polyetherpolyol,
polymerized by the addition of propylene oxide and ethylene
oxide to sucrose: (d) 10-20 wt% of polyesterpolyol,
polymerized by the addition of propylene oxide and ethylene
oxide to phthalic anhydride: and (e) 1-20 wt% of
polyetherpolyol, polymerized by the addition of ethylene
oxide and propylene oxide to brome-substituted glycerine,
the NCO/OH ratio of the composition being in the range of
1.0-2.0; and a hydrofluorocarbon lineage foaming agent
selected from the group consisting of 1,3-pentafluorobutane,
1, 3-pentafluoropropane and mixtures thereof.

Documents:

396-kol-2003-granted-abstract.pdf

396-kol-2003-granted-claims.pdf

396-kol-2003-granted-correspondence.pdf

396-kol-2003-granted-description (complete).pdf

396-kol-2003-granted-drawings.pdf

396-kol-2003-granted-examination report.pdf

396-kol-2003-granted-form 1.pdf

396-kol-2003-granted-form 18.pdf

396-kol-2003-granted-form 2.pdf

396-kol-2003-granted-form 26.pdf

396-kol-2003-granted-form 3.pdf

396-kol-2003-granted-form 5.pdf

396-kol-2003-granted-priority document.pdf

396-kol-2003-granted-reply to examination report.pdf

396-kol-2003-granted-specification.pdf


Patent Number 225978
Indian Patent Application Number 396/KOL/2003
PG Journal Number 49/2008
Publication Date 05-Dec-2008
Grant Date 03-Dec-2008
Date of Filing 21-Jul-2003
Name of Patentee KOREA GAS CORPORATION
Applicant Address 638-1, II-DONG, ANSAN-SI, KYUNGKI-DO
Inventors:
# Inventor's Name Inventor's Address
1 KUN-HYUNG CHOE HYOCHANG VENESVILE 907, 272 HYOCHANG-DONG, YONGSAN-KU, SEOUL
2 SUNG-HEE CHOI LILAC-MAUL 2318-1704, 525-3, SANG-DONG, WONMI-KU, BUCHON-SI, KYUNGKI-DO
3 YEONG-BEOM LEE GILIN VILLA 4-117, 200-2, DONGGYO-DONG MAPO-KU, SEOUL
4 SANG-BUM KIM HYUNDAI APARTMENT 202-601, SINJUNG MAUL, PUNGDUCKCHUN-LI, SUJI-UP, YONGIN-SI, KYUNGKI-DO
PCT International Classification Number C08G 18/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA