U.S. patent application number 10/391925 was filed with the patent office on 2004-09-23 for method of forming high resilience slabstock polyurethane foam.
This patent application is currently assigned to BASF Corporation. Invention is credited to Apichatachutapan, Wassana, Benevenuti, Thomas R., Green, Todd J., Smiecinski, Theodore M..
Application Number | 20040186192 10/391925 |
Document ID | / |
Family ID | 32987794 |
Filed Date | 2004-09-23 |
United States Patent
Application |
20040186192 |
Kind Code |
A1 |
Smiecinski, Theodore M. ; et
al. |
September 23, 2004 |
METHOD OF FORMING HIGH RESILIENCE SLABSTOCK POLYURETHANE FOAM
Abstract
The subject invention provides a method of forming high
resilience slabstock polyurethane foam having random cell
structures to produce latex-like feel and characteristics. The
method includes the first step of providing an isocyanate-reactive
component and an isocyanate component to react with the
isocyanate-reactive component. A first nucleation gas is provided
under low pressure and is added into at least one of the
isocyanate-reactive component and the isocyanate component to
produce a first cell structure in the polyurethane foam. A second
nucleation gas is provided under low pressure, being different than
the first nucleation gas, and is added into at least one of the
isocyanate-reactive component and the isocyanate component to
produce a second cell structure in the polyurethane foam that is
different than the first cell structure.
Inventors: |
Smiecinski, Theodore M.;
(Woodhaven, MI) ; Apichatachutapan, Wassana;
(Woodhaven, MI) ; Green, Todd J.; (Canton, MI)
; Benevenuti, Thomas R.; (Eastpointe, MI) |
Correspondence
Address: |
BASF CORPORATION
LEGAL DEPARTMENT
1609 BIDDLE AVENUE
WYANDOTTE
MI
48192
US
|
Assignee: |
BASF Corporation
|
Family ID: |
32987794 |
Appl. No.: |
10/391925 |
Filed: |
March 19, 2003 |
Current U.S.
Class: |
521/155 ;
521/163; 521/170; 521/172; 521/174 |
Current CPC
Class: |
C08G 2110/005 20210101;
C08G 2110/0008 20210101; C08G 2110/0083 20210101; C08G 18/6688
20130101; C08J 2375/04 20130101; C08J 9/30 20130101 |
Class at
Publication: |
521/155 ;
521/163; 521/170; 521/172; 521/174 |
International
Class: |
C08J 009/00 |
Claims
What is claimed is:
1. A method of forming high resilience slabstock polyurethane foam
having random cell structures to produce latex-like feel and
characteristics, said method comprising the steps of: providing an
isocyanate-reactive component; providing an isocyanate component to
react with the isocyanate-reactive component; providing a first
nucleation gas under low pressure; adding the first nucleation gas
into at least one of the isocyanate-reactive component and the
isocyanate component to produce a first cell structure in the
polyurethane foam; and providing a second nucleation gas under low
pressure, wherein the second nucleation gas is different than the
first nucleation gas; and adding the second nucleation gas into at
least one of the isocyanate-reactive component and the isocyanate
component to produce a second cell structure in the foam that is
different than the first cell structure such that the first cell
structure and the second cell structure enhance the latex-like feel
and characteristics of the slabstock polyurethane foam.
2. A method as set forth in claim 1 wherein the step of adding the
first nucleation gas is further defined as adding the first
nucleation gas into the isocyanate-reactive component.
3. A method as set forth in claim 2 wherein the step of adding the
second nucleation gas is further defined as adding the second
nucleation gas into the isocyanate-reactive component.
4. A method as set forth in claim 3 wherein the step of adding the
first nucleation gas is further defined as adding the first
nucleation gas prior to the addition of the second nucleation
gas.
5. A method as set forth in claim 4 wherein the step of adding the
first nucleation gas is further defined as adding a first
nucleation gas selected from at least one of carbon dioxide gas and
nitrogen gas.
6. A method as set forth in claim 5 wherein the step of adding the
second nucleation gas is further defined as adding a second
nucleation gas selected from at least one of carbon dioxide gas and
nitrogen gas.
7. A method as set forth in claim 6 further comprising the step of
mixing the isocyanate-reactive component having the first
nucleation gas and the second nucleation gas with the isocyanate
component through a mix head to initiate a reaction between the
isocyanate-reactive component and the isocyanate component to form
the slabstock foam.
8. A method as set forth in claim 7 further comprising the step of
adding at least one additive into at least one of the
isocyanate-reactive component and the isocyanate component.
9. A method as set forth in claim 8 wherein the step of adding at
least one additive is further defined as adding an additive
selected from at least one of a surfactant, a chain extender, a
catalyst, a colorant, and a flame retardant.
10. A method as set forth in claim 4 wherein the step of adding the
first nucleation gas is further defined as adding carbon dioxide
gas.
11. A method as set forth in claim 10 wherein the step of adding
the second nucleation gas is further defined as adding nitrogen
gas.
12. A method as set forth in claim 1 wherein the step of adding the
second nucleation gas is further defined as adding the second
nucleation gas in a ratio of from 1:1 to 1:10 relative to the
addition of the first nucleation gas.
13. A method as set forth in claim 1 wherein the step of adding the
second nucleation gas is further defined as adding the second
nucleation gas in a ratio of from 1:1 to 1:4 relative to the
addition of the first nucleation gas.
14. A method as set forth in claim 1 wherein the step of adding the
first nucleation gas is further defined as adding the first
nucleation gas in an amount of from 0.1 liters per minute to 30
liters per minute.
15. A method as set forth in claim 14 wherein the step of adding
the second nucleation gas is further defined as adding the second
nucleation gas in an amount of from 0.1 liters per minute to 20
liters per minute.
16. A method as set forth in claim 1 wherein the step of adding the
first nucleation gas is further defined as adding the first
nucleation gas in an amount of from 2 liters per minute to 20
liters per minute.
17. A method as set forth in claim 16 wherein the step of adding
the second nucleation gas is further defined as adding the second
nucleation gas in an amount of from 0.1 liters per minute to 10
liters per minute.
18. A method as set forth in claim 1 wherein the step of adding the
first nucleation gas is further defined as adding the first
nucleation gas in an amount of from 5 liters per minute to 15
liters per minute.
19. A method as set forth in claim 18 wherein the step of adding
the second nucleation gas is further defined as adding the second
nucleation gas in an amount of from 2 liters per minute to 6 liters
per minute.
20. A method as set forth in claim 17 wherein the step of providing
the isocyanate-reactive component is further defined as providing
an isocyanate-reactive component in an amount from 10 to 500
kilograms per minute.
21. A method as set forth in claim 20 wherein the step of providing
the isocyanate component is further defined as providing an
isocyanate component in an amount from 5 to 250 kilograms per
minute.
22. A method as set forth in claim 21 wherein the step of providing
the isocyanate component is further defined as providing an
isocyanate component at a pressure of from 10 to 2000 pounds per
square inch gauge.
23. A method as set forth in claim 2 wherein the step of adding the
second nucleation gas is further defined as adding the second
nucleation gas into the isocyanate component.
24. A method as set forth in claim 1 wherein the step of adding the
first nucleation gas is further defined as adding the first
nucleation gas into the isocyanate component and wherein the step
of adding the second nucleation gas is further defined as adding
the second nucleation gas into the isocyanate-reactive
component.
25. A method as set forth in claim 1 wherein the step of providing
the isocyanate component is further defined as providing an
isocyanate component selected from at least one of diphenylmethane
diisocyanate, toluene diisocyanate, hexamethylene diisocyanate,
isophorone diisocyanate, and mixtures thereof.
26. A method as set forth in claim 1 wherein the step of providing
the isocyanate component is further defined as providing an
isocyanate component selected from at least one of diphenylmethane
diisocyanate, toluene diisocyanate, and mixtures thereof.
27. A method as set forth in claim 1 wherein the step of providing
the isocyanate component is further defined as providing an
isocyanate component selected from at least one of pure
diphenylmethane diisocyanate, crude diphenylmethane diisocyanate,
and mixtures thereof.
28. A method as set forth in claim 1 wherein the step of providing
the isocyanate component is further defined as providing an
isocyanate component being pure diphenylmethane diisocyanate.
29. A method as set forth in claim 1 wherein the step of providing
the isocyanate-reactive component is further defined as providing
an isocyanate-reactive component selected from at least one of
polyols, polyamines, and polyesters.
30. A method as set forth in claim 1 wherein the step of providing
the isocyanate-reactive component is further defined as providing a
polyol selected from at least one of ethylene glycol, diethylene
glycol, propylene glycol, dipropylene glycol, butane diol,
glycerol, trimethylolpropane, triethanolamine, pentaerythritol and
sorbitol.
31. A method as set forth in claim 1 further including the step of
reacting said isocyanate component and said isocyanate-reactive
component in a trough.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The subject invention relates to a method of forming high
resilience slabstock polyurethane foam having random cell
structures. More specifically, the high resilience slabstock
polyurethane foam formed according to the subject invention having
improved latex-like feel.
[0003] 2. Description of the Related Art
[0004] The use of latex foam in high price, high quality mattresses
has been common in the United States for several years, although
market share has remained relatively low. Latex foam maintains a
much higher share of the mattress materials market in Europe,
because latex foam is considered to be a superior product with
respect to its comfort and durability properties. Recently, U.S.
consumers have been developing a higher sensitivity to sleep habits
and a direct association between bedding quality and the quality of
sleep. The mattress industry is focused on creating more
specialized, higher price, higher quality products resulting in the
growth of the latex foam share of mattress cushion materials.
Traditionally, latex foam has been shown to display superior
resilience, support factor, dynamic and static fatigue resistance
when compared to polyurethane foam for cushioning applications.
Additionally, latex foam is often advertised to provide superior
pressure relief particularly in bedding applications. However,
these comparisons have also typically been made between different
densities of foam, i.e., 4.2 density Latex foam vs. 2.5 density HR
polyurethane foam, while each has a hardness of 28 lb. IFD @ 25%
deflection. Polyurethane foam is not typically formulated in the
same density ranges as latex foam for cushion applications with the
intention of meeting the significantly marketable differences
between urethane and latex. The industry is also focused on finding
other materials that perform and feel like these latex foams, such
as high resilience polyurethane foams.
[0005] High resilience polyurethane foams are produced by reacting
an isocyanate with an isocyanate-reactive component containing two
or more reactive sites, generally in the presence of blowing
agent(s), catalysts, surfactants and other auxiliary additives. The
isocyanate-reactive components are typically polyols, polyesters,
primary and secondary polyamines, or water. The catalysts used
during the preparation of slabstock polyurethane foam promote two
major reactions among the reactants, gelling and blowing. These
reactions must proceed simultaneously and at a competitively
balanced rate during the process in order to yield slabstock
polyurethane foam with desired physical characteristics. Flexible
slabstock foams are generally open-celled materials, which may
require additional processing, such as crushing, to reach a desired
openness.
[0006] Slabstock foam is produced in a foam machine that mixes the
individual reactants, i.e., isocyanate, isocyanate-reactive
components, and additives, in a continuous manner through a mix
head and deposits the reaction product into a trough. The product
begins to froth and rise out of the trough and overflows onto fall
plates. On the fall plates, the product continues to rise and
contacts a conveyor. The product cures as the conveyor carries it
along a length forming the slabstock polyurethane foam. The
conveyors are typically lined with a paper or plastic liner to
allow for easy removal of the slabstock foam. As the foam exits the
machine, it is cut into large blocks.
[0007] Various related art patents disclose methods of forming
slabstock polyurethane foams. These methods include using blowing
agents such as water, air, nitrogen, or carbon dioxide, as shown in
U.S. Pat. No. 5,403,088. Typically, carbon dioxide liquid is added
directly to the polyol component, however it is also known in the
art that it can be added to either or both components. The polyol
component supply must be pressurized to maintain the carbon dioxide
in the liquid state. As the product exits the mix head and as it
froths and rises, the carbon dioxide changes states from a liquid
to a gas and acts as a blowing agent. One primary reason for adding
the carbon dioxide in a liquid state is to ensure that there is a
sufficient amount of blowing agent to produce the foam having a
desired density. However, one disadvantage of using liquid carbon
dioxide is that the polyol component supply must be under pressure,
which is expensive and can be dangerous to maintain the high
pressures.
[0008] Yet another method, shown in U.S. Pat. No. 5,360,831,
discloses adding carbon dioxide gas as a nucleation gas into either
one of the polyol component or the isocyanate component streams for
a foam-in-fabric process. The carbon dioxide gas thickens and
increases the viscosity of the foaming mass to prevent the reacting
components from entering the fine pores of the foam and fabric
capsule, which allows these encapsulating materials to remain as
is, functional, not compromised. Foam-in-fabric processes are
different from slabstock foam processes in that the foam-in-fabric
process is prepared in a batch process and makes only enough foam
to fill a mold, whereas the slabstock process involves continuous
reacting of the components. Fabric is positioned within the mold,
and the components are mixed together and poured into the fabric.
The components react, forming a foam that fills the fabric and
forms the final product.
[0009] The use of other blowing agents, such as nitrogen gas or
various other gases, is shown in WO 02/10245. One distinguishing
factor between a blowing agent and a nucleation gas is the amount
used and the effect that the blowing agent has on the slabstock
foam. Typically, when a gas is added as a blowing agent, a large
amount of the blowing agent is needed to expand the foam during the
frothing and rising stages to control the density of the slabstock
foam. The addition of more blowing agents results in a lower
density foam.
[0010] On the other hand, the related art has used only a single
nucleation gas to improve the characteristics of the foam. The
nucleation gas, such as nitrogen gas or carbon dioxide gas promotes
irregular cell structure and reduces processing of the foam, such
as crushing, after it has cured. If too much nitrogen gas is added
as the nucleation gas, the cells in the slabstock foam are
irregular shaped and become too large forming voids or pits in the
slabstock foam. If the slabstock foam has too many voids, the
slabstock foam loses its resilience and value. If too much carbon
dioxide gas is added as the nucleation gas, the cells are too
uniform and too dense. The slabstock foam prepared with too much
carbon dioxide gas does not have similar physical properties, or
performance characteristics, as that of latex foam. The slabstock
foam of the related art in using a single nucleation gas has not
yet achieved the latex-like feel, while also achieving the
performance characteristics associated with the latex foam.
[0011] However, to date, the industry has been unable to produce a
slabstock polyurethane foam having performance characteristics of
latex foam while also having a substantially similar feel to that
of the latex foam. The industry has been able to achieve
polyurethane foam having performance characteristics similar to
that of latex foam, but the density of the slabstock foam is less
than that of the latex foam and it does not have the similar feel
of latex foam. Accordingly, it would be advantageous to provide a
method of forming a high resilience slabstock polyurethane foam
having random cell structures that has a latex-like feel and
performance characteristics, such as a density equal to that of
latex foam.
BRIEF SUMMARY OF THE INVENTION AND ADVANTAGES
[0012] The subject invention provides a method of forming high
resilience (HR) slabstock polyurethane foam having random cell
structures to produce latex-like feel and characteristics. The
method includes the steps of providing an isocyanate-reactive
component and providing an isocyanate component to react with the
isocyanate-reactive component. A first nucleation gas is provided
under low pressure and is added into at least one of the
isocyanate-reactive component and the isocyanate component to
produce a first cell structure in the foam. A second nucleation
gas, different than the first nucleation gas, is provided under low
pressure and is added into at least one of the isocyanate-reactive
component and the isocyanate component to produce a second cell
structure in the foam that is different than the first cell
structure such that the first cell structure and the second cell
structure enhance the latex-like feel and characteristics of the
slabstock polyurethane foam.
[0013] Accordingly, the subject invention provides a HR slabstock
polyurethane foam having random cell structures that has a
latex-like feel and performance characteristics. The HR slabstock
polyurethane foam is capable of use in any cushioning application
that has traditionally been manufactured with latex foam. The HR
slabstock polyurethane foam outperforms similar latex foams having
a substantially similar density and hardness
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0014] Other advantages of the present invention will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings wherein:
[0015] FIG. 1 is a perspective view a slabstock foam forming
machine having an isocyanate supply line and an isocyanate-reactive
supply line being mixed with nucleation gases and additives prior
to feeding into a mix head; and
[0016] FIG. 2 is a graphical representation of a hysteresis curve
comparing a high resilience slabstock polyurethane foam formed
according to the subject invention with a latex foam.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Referring to the Figures, wherein like numerals indicate
like or corresponding parts throughout the several views, a
slabstock foam forming machine 10 is shown in FIG. 1. The machine
10 is used for forming high resilience (HR) slabstock polyurethane
foam having random cell structures to produce latex-like feel and
characteristics. The slabstock foam machine 10 includes an
isocyanate-reactive supply line 12 and an isocyanate supply line
14. The isocyanate-reactive supply line 12 supplies an
isocyanate-reactive component 30 and the isocyanate supply line
supplies an isocyanate component 32. Both supply lines 12, 14 feed
continuously into a mix head 16 for mixing the two components 30,
32 as they flow through the mix head 16. The mixture of the
components initiates a reaction and is continuously deposited into
a trough 18. The mixture continues to react in the trough 18 and
begins to froth as is known the art. Next, the mixture rises and
overflows from the trough 18 onto fall plates 20. The mixture then
contacts a conveyor 22 and is carried away from the fall plates 20.
The mixture continues to rise along the conveyor 22 and begins to
cure forming the slabstock foam 13. As the slabstock foam 13
reaches the end of the conveyor 22, it is cut into blocks of
various sizes depending upon the application. The conveyor 22 is
lined with a release material 24 to ensure movement of the foam
along the conveyor 22.
[0018] The isocyanate-reactive supply line 12 has a first manifold
26 and a second manifold 28 disposed upstream from the mix head 16.
Each of the manifolds 26, 28 has at least one inlet for adding
additional components to the isocyanate-reactive supply line 12.
These additional components may include at least one of a
nucleation gas, a surfactant, a chain extender, a catalyst, a
colorant, a flame retardant, and the like. Alternately, the
manifolds 26, 28 may be on the isocyanate supply line 14 or on both
supply lines 12, 14.
[0019] The method of the subject invention includes the step of
providing the isocyanate-reactive component 30. Preferably, the
isocyanate-reactive component 30 is selected from at least one of
polyols, polyamines, and polyesters. The polyol may be selected
from at least one of ethylene glycol, diethylene glycol, propylene
glycol, dipropylene glycol, butane diol, glycerol,
trimethylolpropane, triethanolamine, pentaerythritol and sorbitol.
ethylene glycol, diethylene glycol, propylene glycol, dipropylene
glycol, butane diol, glycerol, trimethylolpropane, triethanolamine,
pentaerythritol and sorbitol. Some polyamines include, but are not
limited to, ethylene diamine, tolylene diamine,
diaminodiphenylmethane and polymethylene polyphenylene polyamines,
and aminoalcohols. Examples of aminoalcohols include ethanolamine,
diethanolamine, and triethanolamine, and mixtures thereof.
[0020] Other suitable polyols include polyesters obtained by the
condensation of appropriate proportions of glycols and higher
functionality polyols with polycarboxylic acids. Still further
suitable polyols include hydroxyl-terminated polythioethers,
polyamides, polyesteramides, polycarbonates, polyacetals,
polyolefins and polysiloxanes. Preferred polyols are the polyether
polyols comprising ethylene oxide and/or propylene oxide units.
Other polyols that may be used include dispersions or solutions of
addition or condensation polymers in polyols of the types described
above. Such modified polyols, often referred to as "polymer"
polyols have been fully described in the prior art and include
products obtained by the in-situ polymerization of one or more
vinyl monomers, for example styrene and acrylonitrile, in polymeric
polyols, for example polyether polyols, or by the in situ reaction
between a polyisocyanate and an amino- or hydroxy-functional
compound, such as triethanolamine, in a polymeric polyol. An
example of suitable polyols include, but are not limited to,
PLURACOL.RTM. 2100, 2115, 2120, 2130, 2145, 220, 380, 381, 538,
593, 718, 945, 1051, 1385, 1388, 1509, 1538, 1718 polyols and graft
polyols PLURACOL.RTM. 973, 1117, 1365, 1441, 1442, 1491, 1543,
which are commercially available from BASF Corporation.
[0021] The method also includes the step of providing the
isocyanate component 32 to react with the isocyanate-reactive
component 30. The isocyanate component 32 may be selected from at
least one of diphenylmethane diisocyanate, toluene diisocyanate,
hexamethylene dilsocyanate, isophorone diisocyanate, and mixtures
thereof. Preferably, the isocyanate component 32 is selected from
at least one of diphenylmethane diisocyanate, toluene diisocyanate,
and mixtures thereof. Alternately, the isocyanate component 32 may
be selected from at least one of pure diphenylmethane diisocyanate,
crude diphenylmethane diisocyanate, and mixtures thereof. An
example of suitable isocyanates include, but are not limited to,
LUPRANATE.RTM. MS, LUPRANATE.RTM. M20S, LUPRANATE.RTM. MI, and
LUPRANATE.RTM. 10, LUPRANATE.RTM. M70, LUPRANATE.RTM. M200,
LUPRANATE.RTM. MM103, No. 236 Iso, No. 233 Iso, No. 278 Iso, which
are commercially available from BASF Corporation.
[0022] It is preferable that the isocyanate-reactive component 30
is supplied an amount from 10 to 500 kilograms per minute and the
isocyanate component 32 is supplied in an amount from 5 to 250
kilograms per minute. The isocyanate component 32 may also be
supplied at a pressure of from 10 to 2000 pounds per square inch
gauge. The amount of isocyanate-reactive components 30 and
isocyanate components 32 depends upon the size of the slabstock
polyurethane foam 13 to be formed. These amounts can be used to
produce slabstock polyurethane foams 13 having a height of from 1
to 50 inches and a width of from 12 to 120 inches. If the resulting
slabstock polyurethane foam 13 were larger, then these amounts
would be increased.
[0023] A first nucleation gas 34 is provided under low pressure and
is added into at least one of the isocyanate-reactive component 30
and the isocyanate component 32 to produce a first cell structure
in the polyurethane foam 13. The first nucleation gas 34 is
selected from at least one of carbon dioxide gas and nitrogen gas.
Preferably, the first nucleation gas 34 is added into the
isocyanate-reactive component 30 and is carbon dioxide gas.
However, it is to be appreciated that other gases may behave
chemically similar to that of the carbon dioxide gas and may be
used with the subject invention. The first nucleation gas 34 may be
added in an amount of from 0.1 liters per minute to 30 liters per
minute. Preferably, the first nucleation gas 34 is added in an
amount of from 2 liters per minute to 20 liters per minute. Most
preferably the first nucleation gas 34 is added in an amount of
from 5 liters per minute to 15 liters per minute. If too much
carbon dioxide gas is added, then the first cell structure will be
too uniform and too fine, which results in the foam 13 not having a
latex-like feel. If too little carbon dioxide gas is added, then
the first cell structure is neither uniform nor fine enough.
Examples such as CO, SO2, NO2, and other oxide containing
compounds.
[0024] The subject invention further includes the step of providing
a second nucleation gas 36 different than the first nucleation gas
34. The second nucleation gas 36 is provided under low pressure.
The second nucleation gas 36 is added into at least one of the
isocyanate-reactive component 30 and the isocyanate component 32 to
produce a second cell structure in the polyurethane foam 13
different than the first cell structure. The second nucleation gas
36 is selected from at least one of carbon dioxide gas and nitrogen
gas. Preferably, the second nucleation gas 36 is added into the
isocyanate-reactive component 30 and is nitrogen gas. However, it
is to be understood that other gases may behave chemically similar
to that of the nitrogen gas and may be used with the subject
invention. The second nucleation gas 36 is provided in an amount of
from 0.1 liters per minute to 20 liters per minute. Preferably, the
second nucleation gas 36 is provided an amount of from 1 liters per
minute to 10 liters per minute. Most preferably, the second
nucleation gas 36 is provided an amount of from 2 liters per minute
to 6 liters per minute. If too much nitrogen gas is added, then the
second cell structure becomes too irregular, which results in the
foam 13 having large voids or "pea holes" and the foam is
unacceptable. If too little nitrogen gas is added, then the second
cell structure is too uniform, which does not produce the
latex-like feel and characteristics.
[0025] When determining the amount of the first nucleation gas 34
and the second nucleation gas 36 to be added, the second nucleation
gas 36 is added in a ratio of from 1:1 to 1:10 relative to the
addition of the first nucleation gas 34. Preferably, the second
nucleation gas 36 is added in a ratio of from 1:1 to 1:4 relative
to the addition of the first nucleation gas 34. If too much of the
first nucleation gas 34 is added relative to the second nucleation
gas 36, then the cell structure of the polyurethane foam maybe too
random or not random enough to produce the latex-like feel and
characteristics. For descriptive purposes only, the subject
invention will be described below only in terms of the preferred
first and second nucleation gases 34, 36. It is important to have a
balance between the carbon dioxide gas and the nitrogen gas,
because they compliment one another. The uniform first cell
structure produced by the carbon dioxide gas is broken up by the
irregular second cell structure of the nitrogen gas and vice versa.
Together, both gases produce the slabstock polyurethane foam 13
with the performance characteristics that perform better than the
latex foam when comparing foams having similar density and
hardness. Specifically, the larger, irregular sized second cell
structure improves the resilience and the smaller, regular sized
first cell structure improves the appearance and feel of the foam
13.
[0026] The subject invention further includes the step of adding at
least one additive 40 into at least one of the isocyanate-reactive
component 30 and the isocyanate component 32. The additive 40 is
selected from at least one of a surfactant, a chain extender, a
cross-linker, a catalyst, a colorant, and a flame retardant. A
blowing agent 41, preferably water, but may include freon,
dichloromethane, acetone, liquid carbon dioxide,
chloroflurocarbons, chlorinated solvents like methylene chloride or
trichloroethane, or low-boiling point solvents is also added to the
mix head 12. The blowing agent 41 reacts with isocyanate component
32 to generate hard segments commonly exhibited in preparation of
polyurethane flexible slab foam. Various types of catalyst known to
those skilled in the art include, but are not limited to, amine
catalysts or tin catalysts. It is to be appreciated that other
additives 40 known to those skilled in the art may be added without
deviating from the subject invention. Preferably, the additives 40
are added into the isocyanate-reactive component 30 supply line 12,
as illustrated in FIG. 1.
[0027] Depending upon the types of isocyanate-reactive component
30, isocyanate component 32, nucleation gases 34, 36, or additives
40, the first nucleation gas 34 may be added in the
isocyanate-reactive component 30, while the second nucleation gas
36 is added in the isocyanate component 32. Alternately, the first
nucleation gas 34 may be added into the isocyanate component 32,
while the second nucleation gas 36 may be added into the
isocyanate-reactive component 30. In another embodiment, the first
nucleation gas 34 may be added into the isocyanate-reactive
component 30 and the second nucleation gas 36 may be added into the
isocyanate-reactive component 30.
[0028] Referring to FIG. 1, the first nucleation gas 34 is added to
the isocyanate-reactive component 30 prior to the addition of the
second nucleation gas 36. The isocyanate-reactive component 30
having the first nucleation gas 34 and the second nucleation gas 36
is provided to the mix head 16 in the isocyanate-reactive supply
line 12. The isocyanate component 32 is provided to the mix head 16
in the isocyanate supply line 14. Both supply lines 12, 14 enter
the mix head 16 and are mixed to initiate a reaction between the
isocyanate-reactive component 30 and the isocyanate component 32 to
form the slabstock foam 13.
EXAMPLES
[0029] The HR polyurethane foam 13 was prepared according to the
subject invention having components in part by weight (pbw) set
forth in Table 1. Table 1 includes two formulations of the HR
polyurethane foam 13 to be made in a slabstock process such that
the resulting foams 13 have a different density and hardness.
Specifically, one difference between Example 1 and Example 2 is
isocyanate index. Isocyanate index is defined as the ratio of the
NCO groups in the isocyanate component to the OH groups in the
isocyanate-reactive components.
1TABLE 1 Formulation of HR Slabstock Polyurethane Foam Formulation,
pbw Example 1 Example 2 Isocyanate-reactive 100.0 100.0 component
Colorant 2.0 2.0 Water total 1.50 1.50 Water in polyol 0.02 0.02
Water added 1.33 1.33 Cross-linker 1.00 1.00 Surfactant 2.20 2.20
Amine Catalyst 0.80 0.80 Tin Catalyst 0.60 0.60 Flame Retardant 4.0
4.0 Isocyanate Component 20.57 18.51 Isocyanate index 100 90 Total
PBW 132.5 130.4
[0030] The isocyanate-reactive component is a polyol blend from
PLURACOL.RTM. 2100, and PLURACOL.RTM. 2130 commercially available
from BASF Corporation. The colorant is Blue 8515, sold under the
trademark REACTINT.RTM. commercially available from Milliken
Chemical. The cross-linker is diethanolamine, commonly known as
DEOA LF is commercially available from Chemcentral. The surfactant
is NIAX U-2000 Silicone, commercially available from Crompton Osi.
The amine catalyst may include DABCO.RTM. 33-LV, commercially
available from Air Products and Chemicals, Inc., and NIAX A-1,
commercially available from Crompton Osi. The amine catalyst may be
added in different amount of mixtures without deviating from the
subject invention. The tin catalyst is DABCO.RTM. T-12,
commercially available from Air Products and Chemicals, Inc. The
flame retardant may include ANTIBLAZE.RTM. 100, commercially
available from Rhodia. The isocyanate component may include
LUPRANATE.RTM. T-80 TDI, LUPRANATE.RTM. MS, LUPRANATE.RTM. M20S,
LUPRANATE.RTM. MI, and LUPRANATE.RTM. M10, commercially available
from BASF Corporation.
[0031] Each of the above examples where processed in the slabstock
polyurethane foam machine 10 according to the processing conditions
set forth in Table 2.
2TABLE 2 Processing Conditions for preparing HR Slabstock
Polyurethane Foam Example 1 Example 2 Calibrations, Kg/min.
Isocyanate component 13.19 12.06 Isocyanate-reactive 64.2 65.2
component Colorant 1.3 1.3 Water added 0.853 0.867 Cross-linker
0.642 0.652 Surfactant 1.411 1.434 Amine Catalyst 0.514 0.522 Tin
Catalyst 0.385 0.391 Flame Retardant 2.566 2.607 Processing
Conditions Temp. F. 88 88 Isocyanate Temp. F. 67 67 Isocyanate
Pres., psi 431 425 Rm Temp. .degree. F./Humid %/Atm 78/38/29.2
78/38/29.2 Mixer Speed, RPM 4500 4500 N2 Gas Pressure, psig 25 25
N2 Gas Flow Rate, L/m 1.8 1.8 CO2 Gas Pressure, psig 38 38 CO2 Gas
Flow Rate, L/m 6.0 6.0
[0032] The resulting slabstock polyurethane foam 13 was allowed to
cure 24-48 hours. The slabstock polyurethane foam 13 was cut into
4" thick pieces for use in various tests. These various tests were
also performed on latex foam samples. The latex foam sample was
obtained from FoamOrder.com and was purchased as a Talalay Latex
Twin Mattress. The latex foam was originally 6" thick and was cut
down two inches to a thickness of 4".
[0033] The various tests included determining a density
(lb/ft.sup.3, or pcf) of the sample, an amount of force (Lb.sub.f)
to achieve 25% indentation force deflection (IFD) of the sample,
and a support factor for the sample. The support factor is the
amount of required to achieve 65% IFD divided by the amount of
force to achieve 25% IFD. Another test measured a percentage of
hysteresis loss, discussed more below and shown in FIG. 2, which is
a loss of elasticity of the sample. These specific tests tend to
indicate a "feel" of the polyurethane foam 13 for comparative
analysis to the latex foam. Also, density may vary from the
polyurethane foam 13 and latex foam by up to 0.5 pcf, without
effecting the feel. The relatively high density of the foams 13 can
withstand a variance of up to 0.5 pcf without much difference in
feel. The IFD can be used to determine similarity of feel between
the polyurethane foam 13 and latex foam, but it is preferable to
rely on both the density and IFD.
[0034] A tensile strength (lb/ft.sup.2 or psi), elongation (%), and
tear (lb/in or ppi) test were performed on each of the samples in
accordance with ASTM D-3574. Tensile, tear, and elongation
properties describe the ability of the material to withstand
handling during manufacturing or assembly operations. Another test
determined a resilience of the sample by dropping a steel ball from
a predetermined height onto the sample and measuring a peak height
that the ball bounces. The resilience is expressed in percent of
the predetermined height.
[0035] The samples were also measured for their ability to
withstand wear and tear according to ASTM D-4065 by being subjected
to a pounding of a predetermined weight for 80,000 cycles. An
original sample height was measured and an original amount of force
was determined to reach a value of 40% IFD. Then the sample was
subjected to a pounding of the predetermined weight for 80,000
cycles. The sample height was then remeasured and the percentage of
height loss was determined. The amount of force required to reach
40% IFD was also determined and the percentage of 40% IFD loss was
determined. The samples were also tested to determine if the pass
the California Technical Bulletin 117, which exposes the samples to
an open vertical flame, part A, and a cigarette smoldering, part D.
The amount of time that the samples exhibit a flame after the open
flame is removed is recorded as is a length of a char mark from the
open flame. The cigarette test measures the resistance of the foam
to smoldering propensity of the component and is recorded as
non-smoldering residue weight retention.
[0036] The results of each of the above tests are summarized in
Table 3.
3TABLE 3 Various Test Results for HR Polyurethane Foam vs. Latex
Foam Comparative Comparative Talalay Latex Latex Latex Example 1
Example 1 Example 2 Example 2 Physical Properties Density, pcf 3.87
4.33 4.29 4.36 Tensile, psi 25 6 23 8 HTAG Tensile, psi 23 6 21 4
Elongation, % 176 101 210 132 HTAG 140 25 140 80 Elongation, %
Tear, ppi 2.5 0.9 2.5 0.7 Resilience, % 60 54 55 62 IFD, lb./ 50
sq. in. (4 in.) 25% 25.3 25.7 20.0 19.8 65% 68.8 65.9 58.8 56.2 25%
Return 22.0 19.9 17.3 15.0 Support Factor 2.72 2.57 2.94 2.83
Recovery, % 87 78 87 76 Hysteresis, % 20 30 21 30 Fatigue
Properties Pounding, I3 Height, % Loss 1.1 1.0 1.3 1.0 40% IFD, %
Loss 11 20 11 23 Flammability Properties Cal. T.B. 117 Pass Fail
Pass Fail Vertical Open Flame Afterflame, Sec. 0.0 25.3 0.0 16.8
(ave.) Char Length, In. 1.4 12.0 2.1 12.0 (ave.) Afterflame, Sec.
0.0 27.2 0.0 27.3 (ave.) HT Char Length, In. 1.1 12.0 1.0 12.0
(ave.) HT Cal. T.B. 117 Smoldering % Wt. Retained Pass Fail Pass
Fail (min. 80.0%) Crushed 99.8 0.0 99.3 75.2 Uncrushed 99.9 n/a
99.5 n/a
[0037] Referring to Table 3, Example 1 and Comparative Example 1
have a density that is within 0.5 pcf of each other and an IFD
value at 25% within 0.4. Therefore, Example 1 has a latex-like feel
that is similar to that of Comparative Example 1. Example 1 has an
increased support factor of 6% relative to that of Comparative
Example 1 and an increase in the hysteresis percentage of 33%.
Example 1 also has significantly better tensile, elongation, and
tear properties as set forth in Table 3. Example 1 passes the
vertical open flame and cigarette smoldering test, whereas the
Comparative Example 1 fails both portions of California T.B.
117.
[0038] The hysteresis loss values for the HR slabstock polyurethane
foam 13 samples are significantly less than latex foam samples.
This implies that the polyurethane foams 13 will most likely retain
their original characteristics after flexing. A hysteresis curve is
shown in FIG. 2. The HR polyurethane foam 13 had a better
hysteresis retention and support value than latex foam as depicted
by this curve comparison.
[0039] Example 2 and Comparative Example 2 have a density that is
within 0.07 pcf of each other and an IFD value at 25% within 0.02.
Therefore, Example 2 has a latex-like feel that is similar to that
of Comparative Example 2. Example 2 has an increased support factor
of 4% relative to that of Comparative Example 2 and an increase in
the hysteresis percentage of 30%. Example 2 also has significantly
better tensile strength, elongation, and tear properties as set
forth in Table 3. Example 2 passes the California TB 117 test
protocol, whereas the Comparative Example 2 fails.
[0040] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. The
invention may be practiced otherwise than as specifically described
within the scope of the appended claims.
* * * * *