U.S. patent application number 14/434247 was filed with the patent office on 2015-09-17 for process for producing a low density free-rise polyurethane foam.
The applicant listed for this patent is PROPRIETECT L.P.. Invention is credited to Dorata Ulman, Jing Zhang.
Application Number | 20150259459 14/434247 |
Document ID | / |
Family ID | 50477993 |
Filed Date | 2015-09-17 |
United States Patent
Application |
20150259459 |
Kind Code |
A1 |
Zhang; Jing ; et
al. |
September 17, 2015 |
PROCESS FOR PRODUCING A LOW DENSITY FREE-RISE POLYURETHANE FOAM
Abstract
There is described a process for producing a free-rise
polyurethane foam having a density of less than or equal to about
0.75 pcf. the the process comprises the steps of: (a) contacting:
(i) an isocyanate, (ii) a first polyol comprising a first polymer
chain consisting essentially of propylene oxide units and alkylene
oxide units selected from ethylene oxide, butylene oxide and
mixtures thereof in a weight ratio of propylene oxide units to
alkylene oxide units in the range of from about 90:10 to about
25:75, the polymer chain being terminally capped with the ethylene
oxide units, the first polyol having a primary hydroxyl content of
at least about 70% based on the total hydroxyl content of the first
polyol, (iii) water (iv) a surfactant and (v) a catalyst to form a
foamable reaction mixture; and (b) expanding the foamable reaction
mixture to produce the free-rise polyurethane foam.
Inventors: |
Zhang; Jing; (Toronto,
CA) ; Ulman; Dorata; (Brampton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PROPRIETECT L.P. |
Toronto |
|
CA |
|
|
Family ID: |
50477993 |
Appl. No.: |
14/434247 |
Filed: |
October 10, 2013 |
PCT Filed: |
October 10, 2013 |
PCT NO: |
PCT/CA2013/000855 |
371 Date: |
April 8, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61795075 |
Oct 10, 2012 |
|
|
|
Current U.S.
Class: |
521/115 ;
521/156 |
Current CPC
Class: |
C08G 18/1825 20130101;
C08G 2101/0083 20130101; C08G 18/7671 20130101; C08G 2101/005
20130101; C08G 18/1833 20130101; C08G 18/14 20130101; C08G 18/7664
20130101; C08G 18/6677 20130101; C08G 18/4883 20130101; C08G
18/7621 20130101; C08G 18/2063 20130101; C08G 2101/0008
20130101 |
International
Class: |
C08G 18/08 20060101
C08G018/08; C08G 18/76 20060101 C08G018/76; C08G 18/48 20060101
C08G018/48; C08G 18/20 20060101 C08G018/20; C08G 18/18 20060101
C08G018/18 |
Claims
1. A process for producing a free-rise polyurethane foam having a
density of less than or equal to about 0.75 pcf, the process
comprising the steps of: (a) contacting: (i) an isocyanate, (ii) a
first polyol comprising a first polymer chain consisting
essentially of propylene oxide units and alkylene oxide units
selected from ethylene oxide, butylene oxide and mixtures thereof
in a weight ratio of propylene oxide units to alkylene oxide units
in the range of from about 90:10 to about 25:75, the polymer chain
being terminally capped with the ethylene oxide units, the first
polyol having a primary hydroxyl content of at least about 70%
based on the total hydroxyl content of the first polyol, (iii)
water (iv) a surfactant and (v) a catalyst to form a foamable
reaction mixture; and (b) expanding the foamable reaction mixture
to produce the free-rise polyurethane foam.
2. The process defined in claim 1, wherein the alkylene oxide units
in the first polyol consist of propylene oxide.
3. The process defined in claim 1, wherein the weight ratio of
propylene oxide units to alkylene oxide units in the first polyol
is from about 90:10 to about 70:30.
4-5. (canceled)
6. The process defined in claim 1, wherein the primary hydroxyl
content in the first polyol is at least about 75% based on the
total hydroxyl content of the first polyol.
7-12. (canceled)
13. The process defined in claim 1, wherein the first polyol has a
molecular weight in the range of from about 2,500 to about
15,000.
14-16. (canceled)
17. The process defined in claim 1, wherein the second polyol is
present up to 40 weight percent of the total polyol content in the
reaction mixture.
18-20. (canceled)
21. The process defined in claim 16, wherein the second polymer is
present up to 20 weight percent of the total polyol content in the
reaction mixture.
22. The process defined in claim 1, wherein OH functionality for
polyol content in the reaction mixture is in the range of from
about 2 to about 4.
23. The process defined in claim 1, wherein water is used in an
amount of at least about 10 parts by weight per 100 parts by weight
polyol in the reaction mixture.
24-25. (canceled)
26. The process defined in claim 1, wherein water is used in an
amount in the range of from about 17 parts by weight to about 35
parts by weight per 100 parts by weight polyol in the reaction
mixture.
27. The process defined in claim 1, wherein the reaction mixture is
substantially completely free of added CO.sub.2.
28. The process defined in claim 1, wherein the reaction mixture is
substantially completely free of added organic blowing agents.
29. The process defined in claim 1, wherein the catalyst is an
amine catalyst.
30. The process defined in claim 1, wherein the catalyst is used in
an amount of up to about 1 part by weight per 100 parts by weight
polyol in the reaction mixture.
31-32. (canceled)
33. The process defined in claim 1, wherein the catalyst is used in
an amount in the range of from about 0.25 parts by weight to about
0.35 parts by weight per 100 parts by weight polyol in the reaction
mixture.
34. The process defined in claim 1, wherein the isocyanate is used
in an amount to provide an isocyanate index less than or equal to
about 100.
35. The process defined in claim 1, wherein the isocyanate is used
in an amount to provide an isocyanate index in the range of from
about 45 to about 75.
36-37. (canceled)
38. The process defined in claim 1, wherein the reaction mixture
further comprises a surfactant.
39. The process defined in claim 1, wherein the surfactant is used
in an amount of up to about 5 parts by weight per 100 parts by
weight polyol in the reaction mixture.
40-42. (canceled)
43. The process defined in claim 1, wherein the free-rise
polyurethane foam has a density of in the range of from about 0.30
pcf to about 0.75 pcf.
44-47. (canceled)
48. A free-rise polyurethane foam produced by the process of claim
1.
49. A free-rise flexible polyurethane foam: (i) having a density
less than or equal to about 0.75 pcf, (ii) having a low exotherm
during production, and (iii) being substantially completely free of
a metal catalyst.
50. The free-rise flexible polyurethane foam defined in claim 49,
wherein the density is less than about 0.75 pcf.
51. The free-rise flexible polyurethane foam defined in claim 49,
wherein the density is in the range from about 0.50 pcf to about
0.75 pcf.
52. The free-rise flexible polyurethane foam defined in claim 49,
wherein the density is in the range from about 0.50 pcf to about
0.65 pcf.
53. The free-rise flexible polyurethane foam defined in claim 49,
wherein the foam is substantially completely free of a tin
catalyst.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit under 35 U.S.C.
.sctn.119(e) of provisional patent application Ser. No. 61/795,075,
filed Oct. 10, 2012, the contents of which are hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] In one of its aspects, the present invention relates to a
process for producing a free-rise polyurethane foam having a
density of less than or equal to about 0.75 pcf. In another of its
aspects, the present invention relates to a free-rise flexible
polyurethane foam produced by this process. In yet another of its
aspects, the present invention relates to a free-rise flexible
polyurethane foam: (i) having a density less than or equal to about
0.75 pcf, (ii) having a low exotherm during production, and (iii)
being substantially completely free of metal-containing
catalyst
[0004] 2. Description of the Prior Art
[0005] Isocyanate-based polymers are known in the art. Generally,
those of skill in the art understand isocyanate-based polymers to
be polyurethanes, polyureas, polyisocyanurates and mixtures
thereof.
[0006] It is also known in the art to produce foamed
isocyanate-based polymers. Indeed, one of the advantages of
isocyanate-based polymers compared to other polymer systems is that
polymerization and foaming can occur in situ. This results in the
ability to mold the polymer while it is forming and expanding.
[0007] One of the conventional ways to produce a polyurethane foam
is known as the "one-shot" technique. In this technique, the
isocyanate, a suitable polyol, a catalyst, water (which acts as a
reactive "blowing" agent and can optionally be supplemented with
one or more physical blowing agents) and other additives are mixed
together at once using, for example, impingement mixing (e.g., high
pressure). Generally, if one were to produce a polyurea, the polyol
would be replaced with a suitable polyamine. A polyisocyanurate may
result from cyclotrimerization of the isocyanate component.
Urethane modified polyureas or polyisocyanurates are known in the
art. In either scenario, the reactants would be intimately mixed
very quickly using a suitable mixing technique.
[0008] There are two main reactions in the production of
polyurethane foam which need to be kept in proper balance to
achieve desired product. These reactions are: the blow reaction and
the gelation reaction. If the blowing reaction occurs too quickly,
the resulting growing foam does not have enough strength and
collapses. If the gel reaction occurs too quickly, the resulting
foam will shrink during cooling. Polyurethane foams therefore
require a very balanced formulation. The two reactions--blowing and
gelling--happening simultaneously need to be balanced more
carefully when it is desired to produce a relatively low density
foam.
[0009] Another technique for producing foamed isocyanate-based
polymers is known as the "prepolymer" technique. In this technique,
a prepolymer is produced by reacting a polyol and an isocyanate
wherein one of those components is in excess, in an inert
atmosphere to form a liquid prepolymer terminated with reactive
groups (e.g., isocyanate moieties if the isocyanate is in excess or
active hydrogen moieties if polyol is in excess). To produce the
foamed polymer, the prepolymer is thoroughly mixed with other
components.
[0010] It is known in the art to produce polyurethane foam in the
form of molded foam and slabstock foam.
[0011] Molded foam is typically used in vehicular seating
applications and is made by dispensing into an open mold a foam
composition. The mold is then closed to define mold cavity which
shapes the expanding foam composition on all sides/surfaces.
[0012] Given that molded polyurethane foams are relatively smaller
in size and the cycle time for the molding operation is relatively
short, it is conventional to utilize polyols having a relatively
high reactivity. This allows for the reaction to proceed at an
appropriate rate. These so-called "molded polyols" (described in
more detail below in relation to the "first polyol") typically have
a high content of primary hydroxyl groups. When producing molded
polyurethane foams, it is conventional to heat the mold during foam
production.
[0013] Slabstock polyurethane foam conventionally used in the
production of automotive headliners or other non automotive
applications is known as a foam (e.g., a resilient foam) having at
least one uncontoured surface (i.e., the foam is a "free-rise"
foam).
[0014] In a typical slab polyurethane foam production plant, the
resultant foam is usually produced by dispensing a foamable
composition into a trough having an open top (also known as a
tunnel) and a conveyor bottom to move the composition away from the
mixhead as the foam rises. Low pressure mixing is typically used
and involves metering the components for foam production into a
mixhead equipped with a stirrer (or other suitable agitation means)
at a pressure generally less than 50 psi (usually 2-15 psi). The
components are mixed in the mixhead and the foamable composition is
expanded to produce polyurethane foam. As is known in the art, low
pressure mixing is conventionally used to produce slabstock foam.
It is known to vary the properties of the resulting foam by varying
the nature and/or amount of one or more of the metered
components.
[0015] Commercial slabstock polyurethane foam plants produce foam
"buns" having dimensions such as up to 4 feet or more
(height).times.up to 6 feet (width) or more.times.up to 100 feet
(length) or more. Each bun is then cut into parts of shape and
dimension applicable to the intended use of the foam. For example,
if the foam is used to produce an automotive headliner, a plurality
of shorter length (e.g., 5 feet) buns are cut, depending on the
specifications of the particular automotive headliner being
produced. The shorter length bun is then sliced into sheets of
appropriate thickness (e.g., 1/8 to 1/2 inches). Each sheet is then
used as a component of sandwich headliner composite, which is
trimmed and secured in the automobile. It is also known in the art
to subject each sheet along with other components to further
processing steps such as thermoforming so to confer to the planar
sheet a slightly contoured appearance which more closely assumes
the shape of the roof of the automobile. If the foam is being used
as packaging material, sponge, mattress, cushions etc it is cut
into appropriate pieces for that application. Polyurethane foams
can also be produced in discontinuous way known as box pour.
[0016] Given the large size of the product produced in a slabstock
foam plant, it is conventional to utilize polyols that have a
relatively low reactivity. This allows for the reaction to proceed
at an appropriate rate. These so-called "slabstock polyols"
(described in more detail below in relation to the "second polyol")
typically have a high content of secondary hydroxyl groups. Given
the lower reactivity of slabstockpolyols (compared to molded
polyols), it has been conventional to use metal (e.g., tin)
catalysts along with amine catalysts during the production of
slabstock foams.
[0017] Not surprisingly, when producing slabstock foam, the
exotherm of the foam is a significant safety concern. As is known
in the art, the reactions between isocyanate and polyoland between
isocyanate and water (i.e., when producing a polyurethane foam) are
exothermic liberating a significantly large amount of heat. While
the exotherm in a molded foam is manageable because the size of the
molded foam product is relatively small, so the dissipation of the
heat of the reaction is fast (in fact, as stated above, it is
conventional to heat the mold during foam production), the exotherm
in slabstock foam must be specifically addressed since the product
is so large.
[0018] As used throughout this specification, the term "exotherm",
when used in the context of a polyurethane foam, is intended to
mean heat of reaction experienced by the foam during production.
Thus, the term, "maximum exotherm" is intended to mean the maximum
heat of reaction experienced by the foam during
production--practically, this may be assessed by measuring the
maximum temperature reached by the foam bun (typically in the area
of the core) directly after production. In practice, once a
threshold temperature is reached (typically up to 160.degree. C.
for most open cell flexible slabstock foams and up to 200.degree.
C. for most rigid, semi-rigid and low airflow slabstock foams), in
the presence of air or oxygen, auto-oxidation of the foam may occur
resulting in discoloration (product deterioration) and sometimes
fire (damaging and/or destroying the manufacturing facility).
[0019] It has not been conventional to utilize molded polyols in
the production of slabstock foams because such use can aggravate
the exotherm problem described above. Specifically, due to the
relatively high reactivity of the molded polyols, there is a
greater risk of increasing the exotherm of the reaction and
contributing to the occurrence of the problems mentioned above.
[0020] Typically, slabstock (or free-rise) foams can be produced on
a commercial scale with a density as low as about 1.3 pcf without
the danger of catching the fire. For densities below 1.3 pcf, it
has been conventional to use the auxiliary blowing agents in the
form of gas (CO.sub.2) or low boiling point liquids (e.g.,
methylene chloride and the like). These auxiliary blowing agents do
not generate extra heat but lower density further by expanding
(gas) or evaporating from the system (liquid). Low boiling point
liquids have capacity to even lower exothermic temperature. These
auxiliary blowing agents (particularly low boiling point liquids)
are not friendly to the environment and their use increases the
cost of foam production. Foam production with auxiliary blowing
agents is also more difficult and in some cases requires higher
capital investment.
[0021] There is an ongoing need to be able to produce a low density
(i.e., less than or equal to about 0.75 pcf) slabstock flexible
polyurethane foam having a low exotherm during production and
preferably in the absence of metal catalysts and/or auxiliary
blowing agents.
SUMMARY OF THE INVENTION
[0022] It is an object of the present invention to obviate or
mitigate at least one of the above-mentioned disadvantages of the
prior art.
[0023] It is another object of the present invention to provide a
novel process to produce a free-rise polyurethane foam having a
density of less than or equal to about 0.75 pcf.
[0024] It is yet another object of the present invention to provide
a novel free-rise polyurethane foam having a density of less than
or equal to about 0.75 pcf.
[0025] Accordingly, in one of its aspects, the present invention
provides a process for producing a free-rise polyurethane foam
having a density of less than or equal to about 0.75 pcf, the
process comprising the steps of:
[0026] (a) contacting: (i) an isocyanate, (ii) a first polyol
comprising a first polymer chain consisting essentially of
propylene oxide units and alkylene oxide units selected from
ethylene oxide, butylene oxide and mixtures thereof in a weight
ratio of propylene oxide units to alkylene oxide units in the range
of from about 90:10 to about 25:75, the polymer chain being
terminally capped with the ethylene oxide units, the first polyol
having a primary hydroxyl content of at least about 70% based on
the total hydroxyl content of the first polyol, (iii) water (iv) a
surfactant and (v) a catalyst to form a foamable reaction mixture;
and
[0027] (b) expanding the foamable reaction mixture to produce the
free-rise polyurethane foam.
[0028] In another of its aspects, the present invention provides a
free-rise flexible polyurethane foam: (i) having a density less
than or equal to about 0.75 pcf, (ii) having a low exotherm during
production, and (iii) being substantially completely free of metal
(e.g., tin) catalyst.
[0029] Thus, the present inventors have discovered a novel approach
to the production of a free-rise flexible polyurethane foam having
a density less than or equal to about 0.75 pcf. Specifically, the
present inventors have discovered an approach which allows for the
production of a free-rise flexible polyurethane foam having a
density less than or equal to about 0.75 pcf using so-called molded
polyols while maintaining a relatively low exotherm during
production. Advantageously, this can be achieved while avoiding the
use of auxiliary (e.g., hydrocarbon) blowing agents and/or
tin-based catalyst compounds. While not wishing to be bound by any
particular theory or mode of action, it is believed that through
the use of molded polyols in the production of a free-rise
polyurethane foam would be expected to increase the exotherm of the
foam, this increase in exotherm can be managed and/or offset by
adding more water than stoichiometrically required to the foam
formulation. It is believed that the ability to add more water
allows for absorption of exotherm generated by the use of molded
polyols while concurrently generating more carbon dioxide in situ
(blowing agent) thereby producing a lower density foam while
obviating and/or mitigated shrinkage or collapse of the foam.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] The present process comprises: (a) contacting: (i) an
isocyanate, (ii) a first polyol comprising a first polymer chain
consisting essentially of propylene oxide units and alkylene oxide
units selected from ethylene oxide, butylene oxide and mixtures
thereof in a weight ratio of propylene oxide units to alkylene
oxide units in the range of from about 90:10 to about 25:75, the
polymer chain being terminally capped with the ethylene oxide
units, the first polyol having a primary hydroxyl content of at
least about 70% based on the total hydroxyl content of the first
polyol, (iii) water, (iv) surfactant and (v) a catalyst to form a
foamable reaction mixture; and expanding the foamable reaction
mixture to produce the free-rise polyurethane foam.
[0031] Preferred embodiments of this embodiment of the present
invention may include any one or a combination of any two or more
any of the following features: [0032] the alkylene oxide units in
the first polyol consist of ethylene oxide; [0033] the weight ratio
of propylene oxide units to alkylene oxide units in the first
polyol is from about 90:10 to about 70:30; [0034] the weight ratio
of propylene oxide units to alkylene oxide units in the first
polyol is from about 90:10 to about 80:20; [0035] the weight ratio
of propylene oxide units to alkylene oxide units in the first
polyol is from about 90:10 to about 85:15; [0036] the primary
hydroxyl content in the first polyol is at least about 75% based on
the total hydroxyl content of the first polyol; [0037] the primary
hydroxyl content in the first polyol is in the range of from about
75% to about 95% based on the total hydroxyl content of the first
polyol; [0038] the primary hydroxyl content in the first polyol is
in the range of from about 80% to about 95% based on the total
hydroxyl content of the first polyol; [0039] the primary hydroxyl
content in the first polyol is in the range of from about 80% to
about 90% based on the total hydroxyl content of the first polyol;
[0040] the first polyol has a molecular weight of at least about
2500; [0041] the first polyol has a molecular weight in the range
of from about 2,500 to about 20,000; [0042] the first polyol has a
molecular weight in the range of from about 2,500 to about 17,500;
[0043] the first polyol has a molecular weight in the range of from
about 2,500 to about 15,000; [0044] the first polyol has a
molecular weight in the range of from about 2,800 to about 12,000;
[0045] the first polyol has a molecular weight in the range of from
about 4,000 to about 8,000; [0046] a second polyol is included in
the reaction mixture, the second polyol comprising a second polymer
chain consisting essentially of propylene oxide units and alkylene
oxide units selected from ethylene oxide, butylene oxide and
mixtures thereof in a weight ratio of propylene oxide units to
alkylene oxide units in the range of from about 95:5 to about
60:40, the polymer chain being terminally capped with the alkylene
oxide units, the second polyol having a secondary hydroxyl content
of at least about 70% based on the total hydroxyl content of the
second polyol; [0047] the second polyol is present up to 40 weight
percent of the total polyol content in the reaction mixture; [0048]
the second polyol is present up to 35 weight percent of the total
polyol content in the reaction mixture; [0049] the second polyol is
present up to 30 weight percent of the total polyol content in the
reaction mixture; [0050] the second polyol is present up to 25
weight percent of the total polyol content in the reaction mixture;
[0051] the second polymer is present up to 20 weight percent of the
total polyol content in the reaction mixture; [0052] the OH
functionality for polyol content in the reaction mixture is in the
range of from about 2 to about 4. [0053] water is used in an amount
of at least about 10 parts by weight per 100 parts by weight polyol
in the reaction mixture; [0054] water is used in an amount in the
range of from about 10 parts by weight to about 35 parts by weight
per 100 parts by weight polyol in the reaction mixture; [0055]
water is used in an amount in the range of from about 15 parts by
weight to about 30 parts by weight per 100 parts by weight polyol
in the reaction mixture; [0056] water is used in an amount in the
range of from about 17 parts by weight to about 35 parts by weight
per 100 parts by weight polyol in the reaction mixture; [0057] the
reaction mixture is substantially completely free of added
CO.sub.2; [0058] the reaction mixture is substantially completely
free of added organic blowing agents; [0059] the catalyst is an
amine catalyst; [0060] the catalyst is used in an amount of up to
about 1 part by weight per 100 parts by weight polyol in the
reaction mixture; [0061] the catalyst is used in an amount in the
range of from about 0.05 parts by weight to about 0.5 parts by
weight per 100 parts by weight polyol in the reaction mixture;
[0062] the catalyst is used in an amount in the range of from about
0.15 parts by weight to about 0.4 parts by weight per 100 parts by
weight polyol in the reaction mixture; [0063] the catalyst is used
in an amount in the range of from about 0.25 parts by weight to
about 0.35 parts by weight per 100 parts by weight polyol in the
reaction mixture; [0064] the isocyanate is used in an amount to
provide an isocyanate index less than or equal to about 100; [0065]
the isocyanate is used in an amount to provide an isocyanate index
in the range of from about 45 to about 75; [0066] the isocyanate is
used in an amount to provide an isocyanate index in the range of
from about 45 to about 65; [0067] the isocyanate is used in an
amount to provide an isocyanate index in the range of from about 50
to about 55; [0068] the reaction mixture further comprises a
surfactant; [0069] the surfactant is used in an amount of up to
about 5 parts by weight per 100 parts by weight polyol in the
reaction mixture; [0070] the surfactant is used in an amount of up
to about 4 parts by weight per 100 parts by weight polyol in the
reaction mixture; [0071] the surfactant is used in an amount in the
range from about 0.5 parts by weight to about 3 parts by weight per
100 parts by weight polyol in the reaction mixture; [0072] the
surfactant is used in an amount in the range from about 1.2 parts
by weight to about 1.5 parts by weight per 100 parts by weight
polyol in the reaction mixture; [0073] the free-rise polyurethane
foam has a density of in the range of from about 0.30 pcf to about
0.75 pcf; [0074] the free-rise polyurethane foam has a density of
in the range of from about 0.30 pcf to about 0.80 pcf; [0075] the
free-rise polyurethane foam has a density of in the range of from
about 0.30 pcf to about 0.70 pcf; [0076] the free-rise polyurethane
foam has a density of in the range of from about 0.40 pcf to about
0.60 pcf; and/or [0077] the free-rise polyurethane foam has a
density of about 0.50 pcf.
[0078] In another of its aspects, the present invention provides a
free-rise flexible polyurethane foam: (i) having a density less
than or equal to about 0.75 pcf, (ii) having a low exotherm during
production, and (iii) being substantially completely free of metal
(e.g., tin) catalyst.
[0079] Preferred embodiments of this embodiment of the present
invention may include any one or a combination of any two or more
any of the following features: [0080] the density is less than
about 0.75 pcf; [0081] the density is in the range from about 0.50
pcf to about 0.75 pcf; [0082] the density is in the range from
about 0.50 pcf to about 0.65 pcf; and/or [0083] the foam is
substantially completely free of a tin catalyst.
[0084] The isocyanate suitable for use in the reaction mixture is
not particularly restricted and the choice thereof is within the
purview of a person skilled in the art. Generally, the isocyanate
compound suitable for use may be represented by the general
formula:
Q(NCO).sub.i
wherein i is an integer of two or more and Q is an organic radical
having the valence of i. Q may be a substituted or unsubstituted
hydrocarbon group (e.g., an alkylene or arylene group). Moreover, Q
may be represented by the general formula:
Q.sup.1-Z-Q.sup.1
wherein Q.sup.1 is an alkylene or arylene group and Z is chosen
from the group comprising --O--, --O-Q.sup.1-, --CO--, --S--,
--S-Q.sup.1-S--, --SO.sub.2-- and -Q-N.dbd.C.dbd.N-Q-. Examples of
isocyanate compounds which fall within the scope of this definition
include hexamethylenediisocyanate, 1,8-diisocyanato-p-methane,
xylyldiisocyanate, (OCNCH.sub.2CH.sub.2CH.sub.2OCH.sub.2O).sub.2,
1-methyl-2,4-diisocyanatocyclo-hexane, phenylenediisocyanates,
tolylenediisocyanates, chlorophenylenediisocyanates,
diphenylmethane-4,4'-diisocyanate, naphthalene-1,5-diisocyanate,
triphenyl-methane-4,4',4''-triisocyanate and
isopropylbenzene-alpha-4-diisocyanate.
[0085] In another embodiment, Q may also represent a polyurethane
radical having a valence of i. In this case Q(NCO).sub.i is a
compound which is commonly referred to in the art as a prepolymer.
Generally, a prepolymer may be prepared by reacting a
stoichiometric excess of an isocyanate compound (as defined
hereinabove) with an active hydrogen-containing compound (as
defined hereinafter), preferably the polyhydroxyl-containing
materials or polyols described below. In this embodiment, the
polyisocyanate may be, for example, used in proportions of from
about 30 percent to about 200 percent stoichiometric excess with
respect to the proportion of hydroxyl in the polyol. Since the
process of the present invention may relate to the production of
polyurea foams, it will be appreciated that in this embodiment, the
prepolymer could be used to prepare a polyurethane modified
polyurea.
[0086] In another embodiment, the isocyanate compound suitable for
use in the process of the present invention may be selected from
dimers and trimers of isocyanates and diisocyanates, and from
polymeric diisocyanates having the general formula:
Q'[(NCO).sub.i].sub.j
wherein both i and j are integers having a value of 2 or more, and
Q' is a polyfunctional organic radical, and/or, as additional
components in the reaction mixture, compounds having the general
formula:
L(NCO).sub.i
wherein i is an integer having a value of 1 or more and L is a
monofunctional or polyfunctional atom or radical. Examples of
isocyanate compounds which fall with the scope of this definition
include ethylphosphonicdiisocyanate, phenylphosphonicdiisocyanate,
compounds which contain a .dbd.Si--NCO group, isocyanate compounds
derived from sulphonamides (QSO.sub.2NCO), cyanic acid and
thiocyanic acid.
[0087] See also for example, British patent number 1,453,258, for a
discussion of suitable isocyanates.
[0088] Non-limiting examples of suitable isocyanates include:
1,6-hexamethylene diisocyanate, 1,4-butylene diisocyanate,
furfurylidenediisocyanate, 2,4-toluene diisocyanate, 2,6-toluene
diisocyanate, 2,4'-diphenylmethane diisocyanate,
4,4'-diphenylmethane diisocyanate, 4,4'-diphenylpropane
diisocyanate, 4,4'-diphenyl-3,3'-dimethyl methane diisocyanate,
carbodiimide modified 4,4'-diphenylmethanediisocyanate,
1,5-naphthalene diisocyanate,
1-methyl-2,4-diisocyanate-5-chlorobenzene,
2,4-diisocyanato-s-triazine, 1-methyl-2,4-diisocyanato cyclohexane,
p-phenylenediisocyanate, m-phenylenediisocyanate, 1,4-naphthalene
diisocyanate, dianisidinediisocyanate, bitolylenediisocyanate,
1,4-xylylene diisocyanate, 1,3-xylylene diisocyanate,
bis-(4-isocyanatophenyl)methane,
bis-(3-methyl-4-isocyanatophenyl)methane,
polymethylenepolyphenylpolyisocyanates and mixtures thereof. A more
preferred isocyanate is selected from the group comprising
2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane
diisocyanate and mixtures thereof as well as polymeric MDI which is
also known as drude MDI. Another more preferred isocyanate is
selected from the group comprising 2,4-toluene diisocyanate,
2,6-toluene diisocyanate and mixtures thereof, for example, a
mixture comprising from about 75 to about 85 percent by weight
2,4-toluene diisocyanate and from about 15 to about 25 percent by
weight 2,6-toluene diisocyanate.
[0089] The reaction mixture used to produce the present
polyurethane foam comprises a first polyol comprising a first
polymer chain consisting essentially of propylene oxide units and
alkylene oxide units selected from ethylene oxide, butylene oxide
and mixtures thereof in a weight ratio of propylene oxide units to
alkylene oxide units in the range of from about 90:10 to about
25:75, the polymer chain being terminally capped with the ethylene
oxide units, the first polyol having a primary hydroxyl content of
at least about 70% based on the total hydroxyl content of the first
polyol. These features of the first polyol are typical for polyols
normally used to produce molded foam.
[0090] The first polyol can be used alone or in combination with a
second polyol comprising a second polymer chain consisting
essentially of propylene oxide units and alkylene oxide units
selected from ethylene oxide, butylene oxide and mixtures thereof
in a weight ratio of propylene oxide units to alkylene oxide units
in the range of from about 100:0 to about 60:40, the polymer chain
being terminally capped with the alkylene oxide units, the second
polyol having a secondary hydroxyl content of at least about 95%
based on the total hydroxyl content of the second polyol. These
features of the second polyol are typical for polyols normally used
to produce slab (free rise) foam.
[0091] Within these definitions for the first polyol and the second
polyol, the polyol may be a hydroxyl-terminated backbone of a
member selected from the group comprising polyether, polyester,
polycarbonate, polydiene and polycaprolactone. Preferably, the
polyol is selected from the group comprising hydroxyl-terminated
polyhydrocarbons, hydroxyl-terminated polyformals, fatty acid
triglycerides, hydroxyl-terminated polyesters,
hydroxymethyl-terminated polyesters, hydroxymethyl-terminated
perfluoromethylenes, polyalkyleneether glycols,
polyalkylenearyleneether glycols and polyalkyleneethertriols. More
preferred polyols are selected from the group comprising adipic
acid-ethylene glycol polyester, poly(butylene glycol),
poly(propylene glycol) and hydroxyl-terminated polybutadiene--see,
for example, British patent number 1,482,213, for a discussion of
suitable polyols. Preferably, such a polyether polyol has a
molecular weight in the range of from about 100 to about 10,000,
more preferably from about 100 to about 4,000, most preferably from
about 100 to about 3,500.
[0092] In another embodiment, the second polyol may comprise a
polymer polyol, also known as graft copolymer polyols. As is known
in the art, such polyols are generally polyether polyol dispersions
which are filled with other organic polymers. Such polymer polyols
are useful in load building or improving the hardness of the foam
when compared to using unmodified polyols. Non-limiting examples of
useful polymer polyols include: chain-growth copolymer polyols
(e.g., containing particulate poly(acrylonitrile),
poly(styrene-acrylonitrile) and mixtures thereof), and/or
step-growth copolymer polyols (e.g., PolyHarnstoff Dispersions
(PHD), polyisocyanatepolyaddition (PIPA) polyols, epoxy dispersion
polyols and mixtures thereof). For further information on polymer
polyols, see, for example, Chapter 2 of FLEXIBLE FOAM FUNDAMENTALS,
Herrington et al. (1991) and the references cited therein. If a
polymer polyol is used, it is preferred to mix the polymer polyol
with a base polyol. Generally, mixtures may be used which contain
polymer polyol in an amount in the range of from about 5 to about
50 percent by weight of unmodified polyol present in the
mixture.
[0093] The second polyol may also be a so-called bio-based polyol.
As used throughout this specification, the term "bio-based polyols"
is a generic term intended to encompass polyols derived from
renewable resources such as a vegetable oil or another
bio-originated material.
[0094] The preferred bio-based polyol is a vegetable oil-based
polyol. Non-limiting examples of suitable vegetable oils from which
such a polyols may be derived include soybean oil, safflower oil,
linseed oil, corn oil, sunflower oil, olive oil, canola oil, sesame
oil, cottonseed oil, palm oil, rapeseed oil, tung oil, fish oil,
peanut oil and combinations thereof. Also useful are partially
hydrogenated vegetable oils and genetically modified vegetable
oils, including high oleic safflower oil, high oleic soybean oil,
high oleic peanut oil, high oleic sunflower oil and high erucic
rapeseed oil (crambe oil).
[0095] A suitable method to prepare the bio-based (e.g., vegetable
oil-based) polyol involves reacting the vegetable oil (or mixture
of vegetable oils) with a peroxyacid, providing an epoxidized
vegetable oil. Essentially, some or all of the double bonds of the
vegetable oil may be epoxidized. The epoxidized vegetable oil may
be further reacted with an alcohol, a catalytic amount of
fluoroboric acid and, optionally, water to form the polyol. Such
polyols contain all secondary hydroxyl groups.
[0096] These bio-based polyols may be used directly in a reaction
mixture to produce an isocyanate-based foam such as a polyurethane
foam. Alternatively, the bio-based polyols may be reacted with the
epoxidized vegetable oils described above in the presence of a
fluoroboric acid catalyst and, optionally, water to form a
bio-based polyol suitable for use in a reaction mixture to produce
an isocyanate-based foam such as a polyurethane foam.
[0097] Examples of such preparations are described, for example, in
one or more of [0098] U.S. Pat. No. 6,686,435 [Petrovic et al.];
[0099] U.S. Pat. No. 6,107,433 [Petrovic et al.]; [0100] U.S. Pat.
No. 6,573,354 [Petrovic et al.]; and [0101] U.S. Pat. No. 6,433,121
[Petrovic et al.]. Alternatively, the epoxidation reaction may be
conducted under conditions that result in a polyol having residual
double bonds.
[0102] Also suitable are modified vegetable-oil based polyols
prepared by a hydroformylation process. In this process, a
vegetable oil is reacted with carbon monoxide and hydrogen in the
presence of a Group VIII metal catalyst (e.g., a rhodium catalyst)
to form a hydroformylated vegetable oil. The hydroformylated
vegetable oil is then hydrogenated to form the modified vegetable
oil-based polyol. This process produces polyols containing all
primary hydroxyl groups. These polyols may be used directly in a
reaction mixture to produce an isocyanate-based foam such as a
polyurethane foam. Alternatively, they may be reacted with the
epoxidized vegetable oils described above in the presence of a
fluoroboric acid catalyst and, optionally, water to form a polyol
suitable for use in a reaction mixture to produce an
isocyanate-based foam such as a polyurethane foam.
[0103] A preferred bio-based polyol is described in International
Publication Number WO 2008/106769 [Stanciu et al.].
[0104] In the present process, a catalyst is usually incorporated
in the reaction mixture. The catalyst used in the reaction mixture
is a compound capable of catalyzing the polymerization reaction and
the blowing (foaming) reaction. Such catalysts are known, and the
choice and concentration thereof in the reaction mixture is within
the pure view of a person skilled in the art. See, for example,
U.S. Pat. Nos. 4,296,213 and 4,518,778 for a discussion of suitable
catalyst compounds. Non-limiting examples of suitable catalysts
include tertiary amines and/or organometallic compounds.
Additionally, as is known in the art, when the objective is to
produce an isocyanurate, a Lewis acid must be used as the catalyst,
either alone or in conjunction with other catalysts. Of course it
will be understood by those skilled in the art that a combination
of two or more catalysts may be suitably used. Preferably, the
present process is conducted in the presence of one or more amine
catalyst (reactive/non-fugitive or non-reactive/fugitive). More
preferably, the present process is conducted in the absence of
metal-containing (e.g., tin) catalyst.
[0105] The reaction mixture used to produce the polyurethane foam
typically will further comprise a blowing agent. As is known in the
art, water can be used as an indirect or reactive blowing agent in
the production of foamed isocyanate-based polymers. Specifically,
water reacts with the isocyanate forming carbon dioxide which acts
as the effective blowing agent in the final foamed polymer product.
Alternatively, the carbon dioxide may be produced by other means
such as unstable compounds which yield carbon dioxide (e.g.,
carbamates and the like). The preferred blowing agent for use in
the production of the present foamed isocyanate-based polymer
comprises water.
[0106] It is known in the art that the amount of water used as an
indirect blowing agent in the preparation of a foamed
isocyanate-based polymer (e.g. polyurethane) is conventionally in
the range of from about 0.5 to as high as about 40 or more parts by
weight, preferably from about 1.0 to about 10 parts by weight,
based on 100 parts by weight of the total active
hydrogen-containing compound content in the reaction mixture. As is
known in the art, the amount of water used in the production of a
foamed isocyanate-based polymer typically is limited by the fixed
properties expected in the foamed polymer and by the tolerance of
the expanding foam towards self structure formation, flame
retardance and the like.
[0107] Embodiments of the present invention will now be described
with reference to the following Examples which should not be
construed as limiting the scope of the invention. The term "pbw"
used in the Examples refers to parts by weight.
[0108] In the Examples the following compounds were used:
[0109] 1. Polyol #1, a polyether polyol having an OH number of
39-35 functionality of 3.7-3.8 and a primary hydroxyl content of
greater that 70%, commercially available from Bayer
Corporation;
[0110] 2. Polyol #2, a polyether polyol having an OH number of 56
and a secondary hydroxyl content of greater than 70%, commercially
available from Bayer Corporation;
[0111] 3. FR-38: Fyrol.TM. 38--flame retardant, commercially
available from Supresta LLC;
[0112] 4. Water, indirect blowing agent;
[0113] 5. L-620: Niax.TM. silicone L-620--a silicone surfactant,
commercially available from Momentive Performance Materials
Holdings Inc.;
[0114] 6. L-650: Niax.TM. silicone L-650--a silicone surfactant,
commercially available from Momentive Performance Materials
Holdings Inc.;
[0115] 7. B8229: Tecostab.TM. B8229--a surfactant/stabilizer,
commercially available from Evonik Industries AG;
[0116] 8. Glycerine--a crosslinker;
[0117] 9. 33LV: Dabco.TM. 33LV--amine catalyst, commercially
available from Air Products and Chemicals Inc.;
[0118] 10. C-232: Niax.TM. C-232, amine catalyst, commercially
available from Momentive Performance Materials Holdings Inc.;
[0119] 11. A-1: Niax.TM. A-1, amine catalyst, commercially
available from Momentive Performance Materials Holdings Inc.;
[0120] 12. ZF-10: Jeffcat.TM. ZR-10, amine catalyst, commercially
available from Huntsman Corporation;
[0121] 13. ZR-50: Jeffcat.TM. ZR-50, amine catalyst, commercially
available from Huntsman Corporation;
[0122] 14. LED-204: Jeffcat.TM. LED-204--reactive, acid blocked,
low emissions, low-corrosion type gelling catalyst, commercially
available from Huntsman Corporation;
[0123] 15. TDI: Isocyanate--T-80.TM., toluenediisocyanate,
commercially available from Bayer Corporation or BASF AG;
[0124] 16. MDI: Isocyanate--Polymeric MDI,
polymethylenepolyphenylisocyanate, containing 4,4'-methylene
bisphenylisocyanate with total NCO content 31.0-31.5%, commercially
available from The Dow Chemical Company or Bayer Corporation.
Examples 1-2
[0125] In these Examples, foam samples were produced pursuant to
the formulations provided in Table 1 (all parts are parts by
weight). The methodology used in each Example was as follows.
[0126] A resin mixture was produced by mixing all ingredients
except the isocyanate in a 1 L mixing vessel for a period of
approximately 10 seconds at 3000 rpm. Next, the isocyanate was
added to the mixing vessel and the contexts were mixed for a
further 5 seconds. The contents of the mixing vessel were
transferred to an open (15''.times.12''.times.12'') and allowed to
free rise. box The resulting foam was allowed to cure for at least
24 hours prior to testing.
[0127] Table 2 reports observations during production of the foam
samples and properties of the resulting foams. These observations
and properties illustrate that a good quality slab foam having very
low density can be made using a high primary hydroxyl content
polyol (normally used to produce molded foam) in the absence of
added auxiliary blowing agents while maintaining low exotherm of
the foam during production. The exotherm reported in Table 2 for
the relatively small foam samples translates to an exotherm during
production of a commercial size "bun" (described above) of
approximately 155.degree. C. which is acceptable from a safety
viewpoint.
Example 3
[0128] The methodology of Examples 1 was repeated using the
formulation provided in Table 3 (all parts are parts by
weight).
[0129] Table 4 reports observations during production of the foam
samples and properties of the resulting foam. The positive results
seen in Example 1 were also seen in Example 2 even when a mixture
of polyols (i.e., a high primary hydroxyl content polyol and a high
secondary hydroxyl content polyol) was used with a reactive
(non-fugitive) catalyst system.
Example 4
[0130] The methodology of Examples 1-2 was repeated using the
formulation provided in Table 5 (all parts are parts by
weight).
[0131] Table 6 reports observations during production of the foam
samples and properties of the resulting foam. The positive results
seen in Example 1 (re. low density) were also seen in Example 3
even when a mixture of polyols (i.e., a high primary hydroxyl
content polyol and a high secondary hydroxyl content polyol), a
mixture of isocyanates (i.e., TDI and MDI), a different surfactant
and a different combination of catalysts.
[0132] While this invention has been described with reference to
illustrative embodiments and examples, the description is not
intended to be construed in a limiting sense. Thus, various
modifications of the illustrative embodiments, as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to this description. It is therefore
contemplated that the appended claims will cover any such
modifications or embodiments.
[0133] All publications, patents and patent applications referred
to herein are incorporated by reference in their entirety to the
same extent as if each individual publication, patent or patent
application was specifically and individually indicated to be
incorporated by reference in its entirety.
TABLE-US-00001 TABLE 1 Component Sample A Sample B Polyol #1 100.00
100.0 Glycerine 0.25 0.25 B8229 1.65 -- L-620 -- 1.65 A-1 0.067
0.067 33-LV 0.43 0.43 FR-38 15.00 15.00 Water 17.30 17.30 TDI 95.00
95.00
TABLE-US-00002 TABLE 2 Example 1 Example 2 Cream time (sec) 25 25
Blow off (min) 1'50'' 1'53'' Density (pcf) 0.59 0.60 Airflow
(ft.sup.3/min) 0.57 0.63 CFD 50% (kpa) 2.20 2.20 Tensile (kpa) 61.0
68.7 Elongation (%) 100.0 93.3 Tear strength (N/m) 340.9 359.4
Exotherm (.degree. C.) 135.0 135.0
TABLE-US-00003 TABLE 3 Component Amount Polyol #1 87.50 Polyol #2
12.50 Glycerine 0.50 B8229 1.65 ZR-50 0.20 ZF-10 0.065 FR-38 15.00
Water 17.30 TDI 100.00
TABLE-US-00004 TABLE 4 Example 3 Cream time (sec) 26 Blow off (min)
1'45'' Density (pcf) 0.50 Airflow (ft.sup.3/min) 1.50 CFD 50% (kpa)
4.30 Tensile (kpa) 61.0 Elongation (%) 72.0 Tear strength (N/m)
204.0 Exotherm (.degree. C.) 135.0
TABLE-US-00005 TABLE 5 Component Amount Polyol #1 30.00 Polyol #2
70.00 L-650 1.00 LED-204 0.25 ZR-50 0.25 ZF-10 0.25 FR-38 15.00
Water 20.00 TDI 46.00 MDI 69.00
TABLE-US-00006 TABLE 6 Example 4 Density (pcf) 0.49 Airflow
(ft.sup.3/min) 0.50 CFD 50% (kpa) 15.20 Tensile (kpa) 18.0
Elongation (%) 23.0
* * * * *