Title of Invention

COMPOSITION FOR PREPARING RIGID POLYURETHANE FOAM HAVING GOOD DEMOLDING PROPERTY

Abstract Disclosed is a composition for preparing a rigid polyurethane foam having a good demolding property by defining polyol component and catalyst component. The polyol component comprises 40~60 wt.% of polyol obtained by polymerization with an organic oxide using sorbitol as an initiator, 5~10 wt.% of polyol obtained by polymerization with an organic oxide using ethylene diamine as an initiator, 20~30 wt.% of polyol obtained by polymerization with an organic oxide using toluene diamine or toluene diamine and triethanol amine as a single or a complex initiator, and, optionally, 5~20 wt.% of multivalent polyol of an ester structure, and the catalyst component is chosen in a group comprising a foaming catalyst, a gelling catalyst, a trimerization catalyst, a mixed form of the foaming catalyst and the gelling catalyst, and compound thereof. (FIG. - Nil)
Full Text COMPOSITION FOR PREPARING RIGID POLYURETHANE FOAM
HAVING GOOD DEMOLDING PROPERTY
TECHNICAL FIELD
The present invention relates to a rigid polyurethane foam composition,
and particularly, to a composition for preparing a rigid polyurethane foam having
superior demolding property by defining polyols and reaction catalysts, and
reducing post-expansion rate after foaming without damaging other physical
properties.
BACKGROUND ART
Generally, a rigid polyurethane foam is obtained by reacting a polyol
component and an isocyanate component under existences of reaction catalysts,
a foam blowing agent and a foam stabilizer. The rigid polyurethane foam is a
heat insulating material having the highest heat insulating property among
organic and inorganic thermal insulators, and is used a lot in a refrigerator, a
freezing container, a low temperature storage, etc. which require a higher heat
insulating property. That is because the polyurethane foam consists of closed
cells to have a higher heat insulating property, and a low density foam can be
prepared by controlling a used amount and kind of the foam blowing agent.
However, a polyurethane foam having lower density and thermal conductivity
than that usually used, and having a good plasticity is highly required.
Generally, the rigid polyurethane foam is needed to be hardened in a
foaming jig (mold) under a predetermined temperature range (40°C~55°C) for

a predetermined time after a raw solution is injected. In addition, a difference in
post-expansion rate when demolding in the jig is generated according to the
hardening time. The post-expansion rate after foam blowing of the polyurethane
foam is directly related to size and changing amount of the refrigerator products,
and basically, the amount of post-expansion after the foam blowing is increased
in proportion to the size and thickness.
However, as the produced amount of the refrigerator is increased, as
structure and size of the product become complex and large, and as quality
control of the products becomes rigid, it is required that the expansion rate of the
foam and the hardening time are reduced. However, it can not be realized by the
conventional polyurethane foam, and the number of jig is increased, and thereby,
the producing cost is increased.
DETAILED DESCRIPTION OF THE INVENTION
Therefore, it is an object of the present invention to provide components
of raw solution having improved demolding property and to provide composition
for preparing a rigid polyurethane foam including the same by minimizing post-
expansion rate in demolding from a jig (mold), as maintaining physical properties
and characteristics (heat insulating function, density, dimensional changing rate,
compression intensity, etc.) required as a thermal insulating material to be same
level.
To achieve the above object of the present invention, there is provided
composition for preparing a rigid polyurethane foam having superior demolding
property with minimized post-expansion rate in demolding, by controlling

components and contents of polyols and reaction catalysts in the composition
for the rigid polyurethane comprising reaction catalysts, a chemical foam blowing
dichlorofluoroethane
agent (water), a physical foam blowing agent/(HCFC-141b), an isocyanate, and
a few important polyols.
The composition for preparing a rigid polyurethane according to the
present invention comprises following components:
- a mixed polyol 100 weight parts comprising 40~60 wt.% of polyol (a)
which is obtained by polymerization with alkylene oxide using sorbitol as an
initiator, 5~10 wt.% of polyol (b) which is obtained by polymerization with
alkylene oxide using ethylene diamine as an initiator, 20~30 wt.% of polyol (c)
which is obtained by polymerization with alkylene oxide using toluene diamine
or a mixture of toluene diamine and triethanol amine as a single or complex
initiator, and 5~20 wt.% of multivalent polyol of an ester structure, on a basis of
total weight of mixed polyol (herein, the amount of each polyol is determined
within the above each range so that total wt.% of polyols a, b, c and d could
amount to 100),
- 1.6 ~ 3.5 weight parts of reaction catalysts,
-10 ~ 50 weight parts of a foam blowing agent,
- 1.5 ~ 2.5 weight parts of water, and
-150 ~ 170 weight parts of organic isocyanates.
Also, the present invention relates to a rigid polyurethane foam fabricated
from the above composition for the rigid polyurethane foam.
The present invention uses a mixed polyol of a certain composition,
reaction catalyst, and the foam blowing agent such as a certain amount of water
and HCFC-141b. The rigid polyurethane foam obtained from above composition
according to the present invention has a low post-expansion rate after demolding
as maintaining other physical properties such as thermal insulating function, etc.,
and therefore, has a superior plasticity. Therefore, it is very useful for applying
to the refrigerator.
Most polyols used in general rigid polyurethane are polyhydric alcohol
having an ether structure (C-O-C), and these are obtained by polymerization with
an organic oxide using a compound having two or more active hydrogen as an
initiator.
In case that general alkylene oxide (AO) is used as the above organic
oxide, ethylene oxide (EO), propylene oxide (PO) and a mixture thereof are used
in general, and these can be used in the present invention.
The mixed polyol used in the present invention consists of a polyol which
is obtained by polymerization with an alkylene oxide using sorbrtol of hexa-valent
functional group as an initiator (polyol a), a polyol which is obtained by
polymerization with an alkylene oxide using ethylene diamine (EDA) of tetravalent
of functional group as an initiator (polyol b), a polyol which is obtained by
polymerization with an alkylene oxide using toluene diamine (TDA) of tetra-valent
functional group as a single initiator or a mixture of TDA and triethanol amine
(TEOA) of tri-valent functional group as a complex initiator (polyol c), and a
multivalent polyol having an ester structure (C-O-O) (polyol d).
It is desirable that the component content of the mixed polyol in the
present invention is 40-60 wt.% of polyol a using the sorbitol as an initiator, 5-10

wt.% of polyol b using EDA as an initiator, 20~30 wt.% of polyol c using TDA or
a mixture of TDA and TEOA as a initiator, and 5~20 wt.% of polyol d having an
ester structure. Herein, the amount of each polyol is determined within the above
each range so that total wt.% of polyols a, b, c and d could amount to 100.
The reaction catalysts used in the present invention can be classified into
three kinds, that is, a foaming catalyst for controlling polyurethane major
reaction, a gelling catalyst, and a trimerization catalyst. General pentamethylene
diethylene triamine (PMDETA) can be used as the foaming catalyst affecting to
reactivity of the foam, and dimethyl cyclohexyl amine (DMCHA) can be used as
the gelling catalyst. Relevancy and reactivity between the twocatalysts should
be set appropriately under actual using conditions, and thereby, these catalysts
can affect to the flow and hardness of the foam. Especially, in case that the
polyol controls the flow of the foam as in the present invention, the foaming
catalyst type should be reduced. Also, in the present invention, the trimerization
catalyst may be used additionally, and a mixed catalyst in which the foaming
catalyst and the gelling catalyst are mixed at appropriate ratio may be used, in
this case, preferable mixing ratio (foaming catalyst : gelling catalyst, w/w) is in
a range of 1:1~1:3.
The foaming catalyst is used by the amount of 0.3~0.7 weight parts, the
gelling catalyst is used by the amount of 1.0~1.5 weight parts, and the
trimerization catalyst is used by the amount of 0.3~0.5 weight parts in case of
using per polyol 100 weight parts. Also, in case that the mixed catalyst of the
foaming catalyst and the gelling catalyst is used, the catalyst is used by the
amount of 2.0~3.0 weight parts per polyol 100 weight parts. In economic aspect,
it is desirable that the foaming catalyst which has relative high price is reduced.
In the present invention, the organic isocyanate is used as it is used in
general polyurethane. For example, diphenylmethane diisocyanate (polymeric
MDI) can be used. An index (NCO/OH) for an optical foam is about 1.1~1.2, and
the isocyanate is used by the amount of 15CM7Q weight parts per polyol 100
weight parts.
In the present invention, water is used as a chemical foam blowing agent,
and injected by the amount of 1.5~2.5 weight parts per polyol 100 weight parts.
The HCFC-141b is used as a physical foam blowing agent, and injected by the
amount of about 10~50 weight parts per polyol 100 weight parts.
In addition, a surface active agent may be used in the rigid polyurethane
foam composition of the present invention, and, in this case, a silicon surface
active agent which is used in general rigid polyurethane can be used. The
surface active agent in the present invention reduces a surface tension to
improve miscibility, uniformizes the size of generated pores, and stablizes the
generated foam by controlling pore structure of the foam. In case that the silicon
surface active agent is used in the present invention, it is used by the amount
of 1.0 ~3.0 weight parts per polyol 100 weight parts.
Also, the composition for the rigid polyurethane foam may further includes
one or more additives, such as an ignition delay agent, a filler, a strengthened
fiber, and a colorant.
Hereinafter, examples and comparative examples of the present invention
will be described in detail. In all examples and comparative examples, all "part"
and "%" represent "weight part" and "wt.%" unless it is specifically defined.
In the comparative example and examples 1, 2 and 3 that uses
composition according to the invention, the samples for testing has been
fabricated by using the conventional methods used for such fabrication, including
foaming and hardening of the sample to a rigid polyurethane foam.
Comparative example 1
As shown in table 1, a composition for theTigid polyurethane foam, which
consists of polyol 100 weight parts including polyol A obtained by polymerization
with alkylene oxide (PO: propylene oxide, EO : ethylene oxide) using sorbitol of
hexa-valent functional group as an initiator, polyol B obtained by polymerization
with alkylene oxide using toluene diamine (TDA) of tetra-valent functional group
as an initiator, polyol C obtained by polymerization with the alkylene oxide using
ethylene diamine (EDA) of tetra-valent functional group as an initiator, and polyol
D of poly-functional alcohol having ester structure, 2.0 ~ 2.5 weight parts of
water and 33~35 weight parts of HCFC-141b as foam blowing agents, 0.3~0.5
weight parts of trimerization type and 1.0~1.4 weight parts of mixed type in which
PMDETA and DMCHA are mixed as catalysts, 1.5-2.5 weight parts of silicon
surface active agent, and 140~150 weight parts of polyisocyanate, was
fabricated, on which foaming and hardening were performed to prepare a sample
of rigid polyurethane foam.
Example 1
As shown in table 1, a composition for the rigid polyurethane foam, which
consists of 100 weight parts of polyol compound comprising polyol A, polyol C,
polyol D, and polyol E obtained by polymerization with alkylene oxide using EDA
of tetra-valent functional group as an initiator, 1.5~2,5 weight parts of water and
25-35 weight parts of HCFC-141b as foam blowing agents, 0.3~0.7 weight parts
of PMDETA, 1.2~1.5 weight parts of DMCHA, and 0.3~0.5 weight parts of
trimerization type as catalysts, 1.0~3.0 weight parts of silicon surface active
agent, and 150~170 weight parts of polyisocyanate, was fabricated, on which
foaming and hardening were performed to prepare a sample of rigid
polyurethane foam.
Example 2
As shown in table 1, a composition for the rigid polyurethane foam, which
consists of 100 weight parts of polyol compound comprising polyol A, polyol C,
polyol E, and polyol F having ester structure, 1.5 ~ 2.5 weight parts of water and
25~35 weight parts of HCFC-141b as foam blowing agents, 0.3~0.5 weight parts
of trimerization type 2.0~3.0 weight parts of PMDETA/ DMCHA as catalysts,
1.0~3.0 weight parts of silicon surface active agent, and 150~170 weight parts
of polyisocyanate, was fabricated, on which foaming and hardening were
performed to prepare a sample of rigid polyurethane foam.
Example 3
As shown in table 1, a composition for the rigid polyurethane foam, which
consists of 100 weight parts of polyol compound comprising polyol A, polyol C,
polyol E, and polyol F, 1.5 ~ 2.5 weight parts of water and 25~35 weight parts
of HCFC-141b as foam blowing agents, 0.3~0.7 weight parts of PMDETA,
1.0~1.3 weight parts of DMCHA, and 0.3~0.5 weight parts of trimerization type
as catalysts, 1.0~3.0 weight parts of silicon surface active agent, and 150~170
weight parts of polyisocyanate was fabricated, on which foaming and hardening
were performed to prepare a sample of rigid polyurethane foam.

Results of measuring physical properties for the above samples are
shown in table 1, and the physical properties in table 1 were measured as
follows:
- Just Pack: the amount of polyurethane foam when it is precisely filled
in a predetermined volume when a raw solution is injected into a predetermined
mold, measured by an electronic scale
- reactivity: a major reaction time of the foam (a time point when fiber is
attached to a bar, when a bar is put into the foam in reaction) measured by a
stop watch
- free rise density : density of a foam which is foamed in an opened
chamber without being locked in a mold measured by a scale and a device for
measuring dimensions
- k-factor : generally represented as l, a thermal conductivity of the foam
measured by Auto-l.
- core density : density of a foam which is foamed in a predetermined
moid except outer surface portion measured by an electronic scale and a device
for measuring dimensions
- compression strength : a compression strength of foam measured by
a universal testing machine (UTM)
- dimension changing rate : changes in dimensions according to
environment changing (low temperature, high temperature, or high temperature
and high humidity). The environmental changes of the form were caused by a
thermohydrostat (Korean product, foreign made), and the dimensions before and
after the change were measured by using a device for measuring dimensions,

to calculate the changing rate
- post expansion rate: an expanded degree of the foam when the foam
is taken out from a mold (demolding) before the foam is totally hardened in the
mold (demolding time is reduced), measured as follows,
CD Just pack of the raw solution in a mold (jig) of reference size is
measured.
(2) The raw solution is injected into the mold as over-packing (more than
20%) on a basis of above measured just pack.
(3) A center of the foam is expanded because the hardening time is
shortened than a standard hardening time (staying time in the mold), and the
expanded amount comparing to a standard thickness (mold thickness), when
the foam is demolded, is measured using a device for measuring dimensions to
calculate the expansion rate.
[table 1]
The rigid polyurethane foam fabricated from the above composition
according to the present invention is able to maintain the required physical
properties (thermal insulating function, strength, dimension changing rate, etc.)
as a thermal insulating material. In addition, according to the present invention,

the post-expansion rate is reduced, and thereby, the changed amount of outer
dimension and the demoiding time are reduced to improve productivity of the
form. Especially, as in examples 1 and 3, according to the compositions in which
the polyol advantageous to flow is included and the catalyst of foaming agent
type of high cost is reduced, the cost-saving effect for the thermal insulating
material can be obtained. Therefore, preferable compositions are the above
examples 1 and 3.
INDUSTRIAL APPLICABILITY
As described above, according to the composition for preparing the rigid
polyurethane foam of the present invention, the rigid polyurethane foam which
is able to maintain required physical properties to be same levels as those of the
conventional art, and to minimize post-expansion rate can be fabricated. In
addition, as the post-expansion rate is minimized, hardening time in a foaming
jig after the raw solution is injected, and thereby the productivity can be
increased when the polyurethane foam is applied to the refrigerator, etc.. Also,
since the changed amount of the foam can be reduced when it is applied to
various products, the size of the product can be managed precisely, and
therefore, industrial applicability of the present invention is superior to
conventional art.
As the present invention may be embodied in several forms without
departing from the spirit or essential characteristics thereof, it should also be
understood that the above-described embodiments are not limited by any of the
details of the foregoing description, unless otherwise specified, but rather should

be construed broadly within its spirit and scope as defined in the appended
claims, and therefore all changes and modifications that fall within the meets and
bounds of the claims, or equivalence of such meets and bounds are therefore
intended to be embraced by the appended claims.
CLAIMS.
1. A composition for preparing a rigid polyurethane foam
comprising:
- a mixed polyol 100 weight parts comprising 40~60 wt.% of polyol
(a) which is1 obtained by polymerization with an alkylene oxide using
sorbitol as an initiator, 5~10 wt.% of polyol (b) which is obtained by
polymerization with an alkylene oxide using ethylene diamine as an
initiator, 20~30 wt.% of polyol (c) which is obtained by polymerization with
an alkylene oxide using toluene diamine as a single initiator or a mixture
of toluene diamine and triethanol amine as a complex initiator, and 5~20
wt.% of multivalent polyol (d) of an ester structure, on a basis of total
weight of mixed polyol;
-1.6 ~ 3.5 weight parts of reaction catalyst component including
a foaming catalyst, a gelling catalyst and a trimerization catalyst;
-10 ~ 50 weight parts of a foam blowing agent;
-1.5 ~ 2.5 weight parts of water; and
-150 ~ 170 weight parts of an organic isocyanate.
2. The composition of claim 1, wherein the alkylene oxide is
chosen in a group comprising ethylene oxide, propylene oxide, and a
mixture thereof.
3. The composition of claim 1, wherein the foaming catalyst

is pentamethyl diethylene triamine.
4. The composition of claim 1, wherein the gelling catalyst is
dimethyl cyclohexyl amine.
5. The composition of claim 1, comprising 0.3 ~ 0.7 weight
parts of the forming catalyst, and 1.0 ~ 1.5 weight parts of the gelling
catalyst, per polyol 100 weight parts.
6. The composition of claim 1, wherein the reaction catalyst
comprises a mixed catalyst as a foaming catalyst and a gelling catalyst,
in which a foaming catalyst and a gelling catalyst are mixed in the
appropriate ratio.
7. The composition of claim 6, wherein the mixed ratio
(forming catalyst : gelling catalyst, w/w) of the mixed catalyst is within the
range of 1 : 1 ~ 1 : 3.
8. The composition of claim 6 or 7, comprising the mixed
catalyst in the amount of 2.0 ~ 3.0 weight parts, per polyol 100 weight
parts.
9. The composition of claim 1, comprising the trimerization
catalyst in the amount of 0.3 - 0.5 weight parts, per polyol 100 weight

parts.
10. The composition of claim 1, wherein an index of the organic
isocyanate (NCO/OH) is 1.1~1.2.
11. The composition of claim 1, wherein the foam blowing agent
dichlorofluoroethane
is HCFC-141b
12. The composition of claim 1 further comprising a silicon
surface active agent in the amount of 1.0 ~3.0 weight parts per polyol 100
weight parts.
13. The composition of claim 1 further comprising one or more
additives selected from the group consisting of an ignition delay agent,
a filler, a strengthened fiber, and a colorant.
14. A rigid polyurethane foam having superior demolding
property fabricated from the composition according to any one of claims1
~13.
Disclosed is a composition for preparing a rigid polyurethane foam having a good demolding property by defining
polyol component and catalyst component. The polyol component comprises 40~60 wt% of polyol obtained by polymerization with
an organic oxide using sorbitol as an initiator, 5~10 wt.% of polyol obtained by polymerization with an organic oxide using ethylene
diamine as an initiator, 20~30 wt.% of polyol obtained by polymerization with an organic oxide using toluene diatnine or toluene
diamine and triethanol amine as a single or a complex initiator, and, optionally, 5~20 wt.% of multivalent polyol of an ester structure,
and the catalyst component is chosen in a group comprising a foaming catalyst, a gelling catalyst, a trimerization catalyst, a mixed
form of the foaming catalyst and the gelling catalyst, and compound thereof.

Documents:

400-kolnp-2004-granted-abstract.pdf

400-kolnp-2004-granted-assignment.pdf

400-kolnp-2004-granted-claims.pdf

400-kolnp-2004-granted-correspondence.pdf

400-kolnp-2004-granted-description (complete).pdf

400-kolnp-2004-granted-examination report.pdf

400-kolnp-2004-granted-form 1.pdf

400-kolnp-2004-granted-form 18.pdf

400-kolnp-2004-granted-form 3.pdf

400-kolnp-2004-granted-form 5.pdf

400-kolnp-2004-granted-gpa.pdf

400-kolnp-2004-granted-letter patent.pdf

400-kolnp-2004-granted-reply to examination report.pdf

400-kolnp-2004-granted-specification.pdf

400-kolnp-2004-granted-translated copy of priority document.pdf


Patent Number 214984
Indian Patent Application Number 00400/KOLNP/2004
PG Journal Number 08/2008
Publication Date 22-Feb-2008
Grant Date 20-Feb-2008
Date of Filing 25-Mar-2004
Name of Patentee LG ELECTRONICS INC.
Applicant Address 20, YOIDO-DONG, YONGDUNGPO-KU 150-010 SEOUL REPUBLIC OF KOREA
Inventors:
# Inventor's Name Inventor's Address
1 CHO HYUN-KEUN DONGSUNG APT 113-607, SAPA-DONG 641-550 CHANGWON KYUNG-SANGNAM-DO REPUBLIC OF KOREA
2 KIM JU-HYUN GAENARI 2ND APT 201-708 NAMYANG-DONG 641-100 FDHANGWON KYUNG SANGNAM -DO REPYUBLIC OF KOREA
PCT International Classification Number C08G
PCT International Application Number PCT/KR02/01820
PCT International Filing date 2002-09-27
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2001-0060714 2001-09-28 Republic of Korea