U.S. patent application number 09/997744 was filed with the patent office on 2002-10-31 for blowing agent composition and polymeric foam containing a normally-liquid hydrofluorocarbon and carbon dioxide.
Invention is credited to Duffy, John D., Griffin, Warren H..
Application Number | 20020161063 09/997744 |
Document ID | / |
Family ID | 22976475 |
Filed Date | 2002-10-31 |
United States Patent
Application |
20020161063 |
Kind Code |
A1 |
Duffy, John D. ; et
al. |
October 31, 2002 |
Blowing agent composition and polymeric foam containing a
normally-liquid hydrofluorocarbon and carbon dioxide
Abstract
The present invention relates to blowing agent compositions for
polymeric foams that contain carbon dioxide and a hydrofluorocarbon
having a boiling point of 14.degree. C. or higher and lower than
about 120.degree. C. The present invention also relates to
processes for preparing polymeric foam using such blowing agent
compositions, foamable polymer compositions containing such blowing
agents, and polymeric foams containing such blowing agent
compositions. Suitable blowing agent combinations include: (a) a
composition containing carbon dioxide and at least one
hydrofluorocarbon having a boiling point of 30.degree. C. to about
120.degree. C. that is essentially free of other low boiling ethers
and hydrocarbons; (b) a composition containing greater than 50
weight-percent carbon dioxide and at least one hydrofluorocarbon
having a boiling point of 14.degree. C. or higher to about
120.degree. C.; and (c) carbon dioxide and one hydrofluorocarbon
having a boiling point of 14.degree. C. or higher and lower than
about 120.degree. C.
Inventors: |
Duffy, John D.; (La
Wantzenau, FR) ; Griffin, Warren H.; (Saginaw,
MI) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Family ID: |
22976475 |
Appl. No.: |
09/997744 |
Filed: |
November 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60257482 |
Dec 21, 2000 |
|
|
|
Current U.S.
Class: |
521/50 ;
252/67 |
Current CPC
Class: |
C08J 2203/12 20130101;
C08J 9/144 20130101; C08J 2203/06 20130101; C08J 9/149 20130101;
C08J 9/146 20130101; C08J 2203/182 20130101; C08J 2203/142
20130101; C08J 9/0066 20130101; C08J 2203/202 20130101; C08J 9/122
20130101 |
Class at
Publication: |
521/50 ;
252/67 |
International
Class: |
C08J 009/00 |
Claims
What is claimed is:
1. A blowing agent composition comprising: (a) carbon dioxide; and
(b) at least one hydrofluorocarbon having a boiling point of
30.degree. C. or higher and lower than about 120.degree. C.; said
composition being essentially free of low-boiling ethers and
low-boiling hydrocarbons other than (b).
2. The blowing agent composition of claim 1, wherein said carbon
dioxide is liquefied carbon dioxide.
3. The blowing agent composition of claim 1 wherein the
hydrofluorocarbon is 1,1,1,3,3-pentafluorobutane.
4. The blowing agent composition of claim 3, wherein the
hydrofluorocarbon concentration is 30 wt % or more and 70 wt % or
less based on blowing agent composition weight.
5. The blowing agent composition of claim 1, further comprising at
least one additional blowing agent selected from water and alcohols
having a boiling point lower than about 120.degree. C. at one
atmosphere pressure.
6. A blowing agent composition comprising: (a) carbon dioxide; and
(b) at least one hydrofluorocarbon having a boiling point of
14.degree. C. or higher and lower than about 120.degree. C.;
wherein greater than 50 weight-percent of the composition is carbon
dioxide and wherein a sufficient amount of (b) is present to
produce a polymeric foam having an improved skin quality, lower
open cell content (according to ASTM method D-6226), larger average
cell size, or any combination thereof relative to the same foam
prepared using only carbon dioxide as a blowing agent.
7. The blowing agent composition of claim 6, wherein said carbon
dioxide is liquefied carbon dioxide.
8. The blowing agent composition of claim 6, further comprising at
least one hydrofluorocarbon having a boiling point lower than
14.degree. C.
9. The blowing agent composition of claim 6, wherein said blowing
agent composition comprises only one hydrofluorocarbon.
10. The blowing agent composition of claim 6, further comprising at
least one additional blowing agent selected from water and alcohols
having a boiling point lower than about 120.degree. C.
11. The blowing agent composition of claim 6, that is essentially
free of alcohol.
12. The blowing agent composition of claim 6, further comprising:
(c) at least one hydrofluorocarbon having a boiling point lower
than 14.degree. C.; and (d) at least one additional blowing agent
selected from water, alcohols, ketones, and aldehydes; said
alcohols, ketones and aldehydes having a boiling point lower than
about 120.degree. C.
13. The blowing agent composition of claim 12, wherein (b) is
1,1,1,3,3-pentaflurobutane; (c) is 1,1,1,2-tetrafluoroethane or
1,1,1,2,3,3,3-heptafluoropropane; and (d) is ethanol.
14. A blowing agent composition consisting essentially of carbon
dioxide and one hydrofluorocarbon having a boiling point of
14.degree. C. or higher and lower than about 120.degree. C.
15. A process for preparing polymeric foam comprising expanding a
foamable polymer composition in a process suitable for forming a
polymeric foam using a blowing agent composition selected from a
group consisting of the blowing agent compositions of claims 1, 6,
and 14.
16. A polymeric foam comprising: (a) a polymer having cells defined
therein; (b) carbon dioxide; and (c) at least one hydrofluorocarbon
having a boiling point of 30.degree. C. or higher and lower than
about 120.degree. C.; wherein at least a portion of (b) and (c)
resides in said cells and said polymeric foam is essentially free
of any low-boiling ethers or low-boiling hydrocarbons other than
the one hydrofluorocarbon.
17. The polymeric foam of claim 16, wherein the hydrofluorocarbon
is 1,1,1,3,3-pentafluorobutane.
18. The polymeric foam of claim 16, further containing an infrared
blocker selected from a group consisting of carbon black, graphite,
gold, aluminum, and titanium dioxide dispersed within said
polymer.
19. A polymeric foam comprising: (a) a polymer having cells defined
therein; (b) carbon dioxide; (c) at least one hydrofluorocarbon
having a boiling point of 14.degree. C. or higher and lower than
about 120.degree. C.; (d) at least one hydrofluorocarbon having a
boiling point lower than 14.degree. C.; (e) at least one additional
blowing agent selected from water, alcohols, ketones, and
aldehydes; said alcohols, ketones and aldehydes having a boiling
point lower than about 120.degree. C.; and (f) an infrared blocker
selected from a group consisting of carbon black, graphite, gold,
aluminum, and titanium dioxide; wherein at least a portion of (b),
(c), (d) and (e) reside in said cells and (f) is dispersed in said
polymer.
20. The polymeric foam of claim 19, wherein (c) is
1,1,1,3,3-pentafluorobu- tane.
21. A foamable polymer composition comprising a thermoplastic
polymer having dispersed therein a blowing agent composition
selected from a group consisting of the blowing agent compositions
of claim 1, claim 6, and claim 14.
22. A foamable polymer composition comprising a thermoplastic
polymer having dispersed therein an infrared blocker and a blowing
agent composition that comprises carbon dioxide and one part per
hundred or more, by weight of polymer, of a hydrofluorocarbon
having a boiling point of 14.degree. C. or higher.
23. The foamable polymer composition of claim 22, wherein said
infrared blocker is selected from carbon black and graphite.
24. The foamable polymer composition of claim 22, wherein said
thermoplastic polymer is polystyrene.
Description
CROSS REFERENCE STATEMENT
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/257,482, filed Dec. 21, 2001.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to blowing agent compositions
containing carbon dioxide (CO.sub.2) and a normally-liquid
hydrofluorocarbon (HFC), foamable polymer compositions comprising a
polymer and such blowing agent compositions, the use of such
compositions for preparing polymeric foam, and polymeric foam
containing residuals of the blowing agent composition. A
normally-liquid HFC has a boiling point of 14.degree. C. or higher,
preferably 30.degree. C. or higher, and lower than about
120.degree. C. at one atmosphere of pressure.
[0004] 2. Description of Related Art
[0005] CO.sub.2 is an attractive blowing agent for preparing
polymeric foam because it does not contribute to volatile organic
compound (VOC) emissions and poses little, if any, risk to the
Earth's ozone layer. However, as a sole blowing agent, CO.sub.2
tends to produce polymeric foam having a higher percentage of open
cells, smaller cell sizes, and a higher thermal conductivity than
is desirable, particularly for thermal insulating applications.
Furthermore, polymeric foams having infrared blockers such as
carbon black are difficult to make using only CO.sub.2 as a blowing
agent.
[0006] Hydrofluorocarbons (HFCs) are also attractive blowing agent
components, particularly for preparing thermally insulating
polymeric foams. HFCs are increasingly attractive as replacements
for hydrochlorofluorocarbons (HCFCs) and chlorofluorocarbons
(CFCs), which can contribute to ozone depletion. As with CO.sub.2,
HFCs pose little, if any, risk to the Earth's ozone layer.
Furthermore, HFCs have a thermal conductivity lower than most
polymers or blowing agents (other than HCFCs and CFCs) so HFC
residuals in a polymeric foam can lower the foam's thermal
conductivity.
[0007] Typically, HFCs in blowing agent compositions have a boiling
point of 14.degree. C. or less (HFC(g)). Unfortunately, HFC(g)s
permeate out of polymeric foam and escape into the atmosphere,
which can result in both an increase in the foam thermal
conductivity and organic emissions.
[0008] A need exists in the art of blowing agents for a composition
that is safe for the environment and produces thermally insulating
polymeric foam. Preferably, the composition contains a HFC that
remains in polymeric foam longer than HFC(g)s thereby slowing or
reducing thermal conductivity increases and organic emission levels
experienced when using HFC(g)s. More preferably, the composition
comprises CO.sub.2 and a HFC that at least partially compensates
for CO.sub.2 deficiencies.
DEFINITIONS
[0009] "Hydrofluorocarbon" and "HFC" are interchangeable terms and
refer to an organic compound containing hydrogen, carbon, and
fluorine. The compound is substantially free of halogens other than
fluorine.
[0010] "Boiling point" refers to the boiling point at one
atmosphere pressure.
[0011] "Normally-gaseous material" refers to a material that has a
boiling point lower than 14.degree. C.
[0012] "Normally-liquid hydrofluorocarbon", "normally-liquid HFC",
and "HFC(1)" are interchangeable terms and refer to a HFC that has
a boiling point of 14.degree. C. or higher and lower than about
120.degree. C.
[0013] "Normally-gaseous hydrofluorocarbon", "normally-gaseous
HFC", and "HFC(g)" are interchangeable terms and refer to a HFC
that has a boiling point lower than 14.degree. C.
[0014] "Low-boiling alcohol" and "LBA" are interchangeable terms
and refer to an alcohol having a boiling point lower than about
120.degree. C.
[0015] "Low-boiling carbonyl compound" and "LBC" are
interchangeable terms and refer to an aldehyde or a ketone having a
boiling point lower than about 120.degree. C.
[0016] "Low-boiling hydrocarbons" and "LBHs" are interchangeable
terms and refer to hydrocarbons having a boiling point lower than
55.degree. C., including halogenated hydrocarbons.
[0017] "Low-boiling ethers" and "LBES" are interchangeable terms
and refer to ethers having a boiling point lower than 55.degree.
C., including halogenated ethers.
[0018] "Fresh" refers to within one month, preferably within one
week, more preferably within one day, still more preferably within
one hour, most preferably immediately after manufacture.
[0019] A polymeric foam or blowing agent composition that is
"essentially free" of a specified component or components refers,
respectively, to a polymeric foam or blowing agent composition that
contains ten weight-percent (wt %) or less, preferably five wt % or
less, more preferably one wt % or less, still more preferably 0.5
wt % or less, most preferably zero wt % of the specified
component(s) based, respectively, on foam or blowing agent
composition weight.
[0020] A blowing agent composition "consisting essentially of" a
specified component or components is free from any unspecified
components at concentrations that modify how the composition
performs in preparing polymeric foam. Commonly, a blowing agent
composition "consisting essentially of" a specified component or
components refers to a composition that contains 90 wt % or more,
preferably 95 wt % or more, more preferably 99 wt % or more, still
more preferably 99.5 wt % or more, most preferably 100 wt % of the
specified component(s). Wt % is relative to weight of blowing agent
composition.
BRIEF SUMMARY OF THE INVENTION
[0021] In a first aspect, the present invention is a blowing agent
composition comprising: (a) carbon dioxide; and (b) at least one
hydrofluorocarbon having a boiling point of 30.degree. C. or higher
and lower than about 120.degree. C.; said composition being
essentially free of low-boiling ethers and low-boiling hydrocarbons
other than (b). 1,1,1,3,3-pentafluorobutane is a preferred
hydrofluorocarbon in the first aspect.
[0022] In a second aspect, the present invention is a blowing agent
composition comprising: (a) carbon dioxide; and (b) at least one
hydrofluorocarbon having a boiling point of 14.degree. C. or higher
and lower than about 12020 C.; wherein greater than 50
weight-percent of the composition is carbon dioxide and wherein a
sufficient amount of (b) is present to produce a polymeric foam
having an improved skin quality, lower open cell content (according
to ASTM method D-6226), larger average cell size, improved skin
quality, or any combination thereof relative to the same foam
prepared using only carbon dioxide as a blowing agent. Preferably,
at least one hydrocarbon in (b) of the second aspect is
1,1,1,3,3-pentafluorobutane.
[0023] One preferred embodiment of the second aspect further
comprises: (c) at least one hydrofluorocarbon having a boiling
point lower than 14.degree. C.; and (d) at least one additional
blowing agent selected from water, alcohols, ketones and aldehydes;
said alcohols, ketones and aldehydes having a boiling point lower
than about 120.degree. C. at atmospheric pressure.
[0024] The first and second aspects of the invention can further
comprise additional blowing agents selected from water and alcohols
having a boiling point lower than about 120.degree. C.,
particularly ethanol.
[0025] In a third aspect, the present invention is a blowing agent
composition consisting essentially of carbon dioxide and one
hydrofluorocarbon having a boiling point of 14.degree. C. or higher
and lower than about 120.degree. C. Carbon dioxide is preferably
liquefied in each of the embodiments of the first three
aspects.
[0026] In a fourth aspect, the present invention is a process for
preparing polymeric foam comprising expanding a foamable polymer
composition in a process suitable for forming a polymeric foam
using a blowing agent composition selected from a group consisting
of the blowing agent compositions of the first three aspects.
[0027] In a fifth aspect, the present invention is a polymeric foam
comprising: (a) a polymer having cells defined therein; (b) carbon
dioxide; and (c) at least one hydrofluorocarbon having a boiling
point of 30.degree. C. or higher and lower than about 120.degree.
C.; wherein at least a portion of (b) and (c) resides in said cells
and said polymeric foam is essentially free of any low-boiling
ethers or low-boiling hydrocarbons other than the hydrofluorocarbon
(c).
[0028] In a sixth aspect, the present invention is a polymeric foam
comprising: (a) a polymer having cells defined therein; (b) carbon
dioxide; (c) at least one hydrofluorocarbon having a boiling point
of 14.degree. C. or higher and lower than about 120.degree. C.; (d)
at least one hydrofluorocarbon having a boiling point lower than
14.degree. C.; (e) at least one additional blowing agent selected
from water, alcohols, ketones, and aldehydes; said alcohols,
ketones and aldehydes having a boiling point lower than about
120.degree. C.; and (f) an infrared blocker selected from a group
consisting of carbon black, graphite, gold, aluminum, and titanium
dioxide; wherein at least a portion of (b), (c), (d), and (e)
reside in said cells and (f) is dispersed in said polymer.
[0029] Blowing agent components usually migrate from within
polymeric foam and air migrates into polymeric foam over time.
Therefore, preferably characterize polymeric foams within the time
frame set forth by "fresh", most preferably immediately after
manufacture of the foam. Blowing agents have less of an opportunity
to escape from a foam and air has less of an opportunity to migrate
into a foam within the "fresh" time frame.
[0030] In a seventh aspect, the present invention is a foamable
polymer composition comprising a thermoplastic polymer having
dispersed therein a blowing agent composition selected from a group
consisting of the blowing agents of the first three aspects of the
present invention.
[0031] In an eighth aspect, the present invention is a foamable
polymer composition comprising a thermoplastic polymer having
dispersed therein an infrared blocker and a blowing agent
composition that comprises carbon dioxide and a hydrofluorocarbon
having a boiling point of 14.degree. C. or higher.
[0032] The present invention addresses a need in the art for a
blowing agent composition that is safe for the environment and
produces a thermally insulating polymeric foam. The composition
contains a HFC(1), which tends to remain in polymeric foam longer
than HFC(g)s, slowing or reducing thermal conductivity increases
and organic emission levels experienced when using HFC(g)s.
DETAILED DESCRIPTION OF THE INVENTION
[0033] This invention relates to a blowing agent composition
comprising CO.sub.2 and a HFC(1). Some embodiments of the present
invention may also comprise additional blowing agents.
[0034] Blowing agent compositions of the present invention contain
an amount of CO.sub.2 from greater than zero wt % up to, but not
including, 100 wt % based on blowing agent composition weight.
Herein, CO.sub.2 in a blowing agent composition is preferably
liquefied CO.sub.2. The concentration of CO.sub.2 is generally
greater than 20 wt %, preferably greater than 30 wt %, more
preferably greater than 40 wt %, and most preferably greater than
50 wt %, based on blowing agent composition weight.
[0035] Blowing agent compositions that are mostly (greater than 50
wt % based on blowing agent composition weight) CO.sub.2 are
desirable because CO.sub.2 is a readily available material that is
safe for Earth's atmosphere. However, experience shows that
preparing thermoplastic foams using a blowing agent composition
that is mostly CO.sub.2 is difficult to process, often resulting in
a foam having poor foam skin quality and an open-cell structure.
Foams having poor skin quality have an unacceptable level of
surface irregularities such as cracks, stretch marks, and ripples.
Fabrication of thermoplastic foams containing infrared blockers,
such as graphite and carbon black, are particularly challenging
with a CO.sub.2 blowing agent and often results in foams with
smaller cell sizes, higher percentage of open cells, and/or more
highly fractured skin surfaces than foams prepared without the
infrared blockers.
[0036] The present invention is the result of discovering that
including at least one HFC(1) with CO.sub.2 can overcome the
difficulties associated with a CO.sub.2 blowing agent.
Surprisingly, including one part per hundred or more, preferably
two parts or more, more preferably three parts or more HFC(1), by
weight of a polymer resin, in a CO.sub.2 blowing agent composition
is generally sufficient to prepare a polymeric foam that has better
skin quality (fewer surface irregularities), larger average cell
size, lower open-cell content, or any combination thereof as
compared to the same foam prepared using only CO.sub.2 as a blowing
agent.
[0037] HFC(1)s are also particularly desirable in preparing
thermally insulating foam. HFCs, in general, have a lower thermal
conductivity than polymers. Therefore, residual HFC in a polymeric
foam typically lowers the foam's thermal conductivity relative to a
similar polymeric foam without the residual HFC. HFC(1)s have a
lower vapor pressure than HFC(g)s, therefore they tend to permeate
out of polymeric foam less readily than HFC(g)s. As a result,
blowing agent compositions containing an HFC(1) produce a polymeric
foam that demonstrates a slower thermal conductivity increase over
time than a polymeric foam prepared using a HFC(g) instead of
HFC(1). Furthermore, because HFC(1)s tend to remain in a foam
longer than HFC(g)s, they contribute less to organic emissions than
HFC(g)s. HFC(1)s are also easier to handle than normally-gaseous
materials because of their lower vapor pressure. For example,
pressure liquefaction commonly used for normally-gaseous materials
is not necessary for HFC(1)s.
[0038] HFC(1)s suitable for use in the present invention include
any HFC having a boiling point of 14.degree. C. or higher,
preferably 30.degree. C. or higher, and lower than about
120.degree. C. Examples of suitable HFC(1)s include aliphatic
compounds such as 1,1,1,3,3-pentafluoropropane (HFC-245fa),
1,1,1,3,3-pentafluorobutane (HFC-365mfc), 1-fluorobutane,
nonafluorocyclopentane, perfluoro-2-methylbutane, 1-fluorohexane,
perfluoro-2,3-dimethylbutane, perfluoro-1,2-dimethylcyclobutane,
perfluorohexane, perfluoroisohexane, perfluorocyclohexane,
perfluoroheptane, perfluoroethylcyclohexane, perfluoro-1,3-dimethyl
cyclohexane, and perfluorooctane; as well as aromatic compounds
such as fluorobenzene, 1,2-difluorobenzene; 1,4-difluorobenzene,
1,3-difluorobenzene; 1,3,5-trifluorobenzene;
1,2,4,5-tetrafluorobenzene, 1,2,3,5-tetrafluorobenzene,
1,2,3,4-tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene,
and 1-fluro-3-(trifluoromethyl)ben- zene. Aromatic HFCs may be
especially compatible with aromatic polymers and, as a result,
remain within polymeric foam prepared with an aromatic polymer
longer than non-aromatic HFCs. Therefore, aromatic HFCs may be
attractive for use with aromatic polymers. In general, HFC-365mfc
and HFC-245fa are preferred due to their increasing availability
and ease of use, with HFC-365mfc more preferred because it has a
higher boiling point than HFC-245fa. The HFC(1)s having a boiling
point higher than 30.degree. C., such as HFC-365mfc, are
particularly desirable because they do not require liquefaction
during foam processing.
[0039] Additionally, within the blowing agent compositions of the
present invention, the HFC(1) preferably has a boiling point of
30.degree. C. or higher if the composition comprises CO.sub.2 and
only one HFC(1); and the composition is essentially free of
low-boiling ethers and low-boiling hydrocarbons other than the
HFC(1).
[0040] The HFC(1) in a blowing agent composition can have a boiling
point of 14.degree. C. or higher to about 12.degree. C. if: (a)
greater than 50 wt % of the blowing agent composition is CO.sub.2,
and the composition contains at least one HFC(1); (b) greater than
50 wt % of the composition is CO.sub.2 and the composition further
comprises a HFC having a boiling point lower than 14.degree. C. and
at least one additional blowing agent selected from water,
low-boiling alcohols and low boiling carbonyl compounds; or (c) the
composition consists essentially of CO.sub.2 and one HFC.
[0041] The concentration of HFC(1), relative to the total weight of
blowing agent composition, is greater than zero wt %, typically one
wt % or more, preferably two wt % or more, more preferably three wt
% or more; and typically 95 wt % or less. Above 95 wt %, excessive
polymer plasticization occurs, yielding poor polymeric foam. The
concentration of HFC(1) relative to the blowing agent composition,
for example, can be 5 wt % or more, 10 wt % or more, 25 wt % or
more; 50 wt % or more wt %, or 75 wt % or more as desired.
[0042] The blowing agent composition may further comprise at least
one additional blowing agent. Additional blowing agents are useful
for reducing polymeric foam density by increasing total moles of
blowing agent. Preferably, additional blowing agents allow one to
increase moles of blowing agent without suffering from at least one
of the following: decreased cell size, increased density, decreased
dimensional stability, and increased cost.
[0043] Additional blowing agents include physical and chemical
blowing agents. Suitable physical blowing agents include water;
HFC(g)s such as methyl fluoride, difluoromethane (HFC-32),
perfluoromethane, ethyl fluoride (HFC-161), 1,1-difluoroethane
(HFC-152a), 1,1,1-trifluoroethane (HFC-143a),
1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethan- e
(HFC-134a), pentafluoroethane (HFC-125), perfluoroethane,
2,2-difluoropropane (HFC-272fb), 1,1,1-trifluoropropane
(HFC-263fb), and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea);
inorganic gases such as argon, nitrogen, and air; organic blowing
agents such as aliphatic hydrocarbons having from one to nine
carbons (C.sub.1-C.sub.9) including methane, ethane, propane,
n-butane, isobutane, n-pentane, isopentane, neopentane,
cyclobutane, and cyclopentane; fully and partially halogenated
aliphatic hydrocarbons having from one to four carbons
(C.sub.1-C.sub.4); and aliphatic alcohols having from one to five
carbons (C.sub.1-C.sub.5) such as methanol, ethanol, n-propanol,
and isopropanol; carbonyl containing compounds such as acetone,
2-butanone, and acetaldehyde. Suitable chemical blowing agents
include azodicarbonamide, azodiisobutyronitrile,
benzenesulfo-hydrazide, 4,4-oxybenzene sulfonyl semi-carbazide,
p-toluene sulfonyl semi-carbazide, barium azodicarboxylate,
N,N'-dimethyl-N,N'-dinitrosoterephthalamide, trihydrazino triazine
and sodium bicarbonate. Preferred additional blowing agents include
LBAs such as methanol, ethanol, and isopropanol; LBCs such as
acetone, 2-butanone, and acetaldehyde; water; and HFC(g)s.
[0044] In general, the concentration of any individual additional
blowing agent is desirably below the solubility limit of that
blowing agent in the polymer, taking into account the presence of
the rest of the blowing agent composition. A skilled artisan can,
without undue experimentation, determine appropriate amounts of
additional blowing agents for a given blowing agent composition.
Additional blowing agents can comprise 20 wt % or less, more
generally 30 wt % or less, still more generally 40 wt % or less,
most generally 60 wt % or less of the blowing agent composition.
The blowing agent composition can be substantially free of any
additional blowing agent.
[0045] HFC(1), CO.sub.2, and any additional blowing agents account
for 100 wt % of the blowing agent composition.
[0046] One example of a suitable blowing agent composition has 30
wt % to 70 wt % (inclusive) HFC-365mfc with the balance to 100 wt %
being CO.sub.2.
[0047] Another example of a suitable blowing agent composition is
20-30 wt % HFC-365mfc, and the balance to 100 wt % being CO.sub.2
and at least one additional blowing agent (preferably HFC-134a,
ethanol, or a mixture thereof).
[0048] The present invention further relates to a process for
preparing a polymeric foam by expanding a polymer in a process
suitable for forming a polymeric foam and using a blowing agent
composition of the present invention. Typically, the blowing agent
composition is present at a concentration, by weight relative to
polymer weight, of greater than zero parts per hundred (pph) and
less than or equal to 20 pph. Blowing agent compositions above 20
pph, based on polymer, produce polymeric foam having undesirable
properties such as higher densities than desired for insulation
applications. The concentration of blowing agent composition, based
on polymer weight, desirably is 4 pph or more, preferably 5 pph or
more; and 18 pph or less, preferably 15 pph or less, more
preferably 12 pph or less.
[0049] Any conventional blown foam process is suitable for
preparing a polymeric foam using the blowing agent composition of
this invention. Generally, prepare a polymeric foam by plasticizing
a polymer (typically heat plasticizing a thermoplastic polymer),
incorporating therein a blowing agent composition at an initial
pressure to form a foamable polymer composition, exposing the
foamable polymer composition to a foaming pressure that is lower
than the initial pressure, and allowing the foamable polymer
composition to expand into a polymeric foam. Normally, plasticize a
thermoplastic polymer by heating it to a processing temperature at
or above the polymer's glass transition temperature, forming a heat
plasticized polymer composition. Add the blowing agent composition
to the heat plasticized polymer composition to form a foamable
polymer composition. Add components of the blowing agent
composition individually or in any number of combinations.
Incorporate the blowing agent composition into the plasticized
polymer composition by a batch or continuous process, such as
mixing with an extruder or mixer blender. The initial pressure is
sufficient to prevent substantial expansion of the foamable polymer
composition and to generally disperse the blowing agent therein.
The initial pressure is often greater than atmospheric pressure
(760 mm of mercury). Either reduce the pressure around the foamable
polymer composition to a foaming pressure or transport the foamable
polymer composition into a foaming zone at a foaming pressure to
initiate expansion of the foamable polymer composition into a foam.
The foaming pressure is less than the initial pressure and can be
above or below atmospheric pressure, but is typically atmospheric
pressure. The foaming pressure is sufficiently low to allow the
blowing agent composition to expand the foamable polymer
composition.
[0050] Cooling the heat plasticized foamable polymer composition
below the processing temperature prior to exposing the foamable
polymer composition to the foaming pressure can improve polymeric
foam properties. One may cool the foamable polymer composition in
an extruder or other mixing device or in separate heat
exchangers.
[0051] A skilled artisan recognizes there are many variations of
the general procedure as well as other ways to prepare polymeric
foam that are suitable within the present invention. For example,
U.S. Pat. No. 4,323,528, herein incorporated by reference,
discloses a process for making polyolefin foams via an accumulating
extrusion process. The accumulating extrusion process comprises: 1)
mixing a thermoplastic material and a blowing agent composition to
form a foamable polymer composition; 2) extruding the foamable
polymer composition into a holding zone maintained at a temperature
and pressure that precludes foaming; the holding zone has a die
defining an orifice opening into a zone of lower pressure at which
the foamable polymer composition foams and an openable gate closing
the die orifice; 3) periodically opening the gate and,
substantially concurrently, applying mechanical pressure by means
of a movable ram on the foamable polymer composition to eject it
from the holding zone through the die orifice into the zone of
lower pressure, and 5) allowing the ejected foamable polymer
composition to expand to form the polymeric foam.
[0052] Suitable polymers for use in the present invention include
thermoplastic polymers, particularly those from a group consisting
of vinyl aromatic polymers such as polystyrene; rubber-modified
vinyl aromatic polymers such as high impact polystyrenes (HIPS);
vinyl aromatic copolymers such as styrene/acrylonitrile or
styrene/butadiene; hydrogenated vinyl aromatic polymers and
copolymers such as hydrogenated polystyrene and hydrogenated
styrene/butadiene copolymers; alpha-olefin homopolymers such as low
density polyethylene, high density polyethylene and polypropylene;
linear low density polyethylene (an ethylene/octene-1 copolymer)
and other copolymers of ethylene with a copolymerizable,
mono-ethylenically unsaturated monomer such as an alpha-olefin
having from 3 to 20 carbon atoms; copolymers of propylene with a
copolymerizable, mono-ethylenically unsaturated monomer such as an
alpha-olefin having from 4 to 20 carbon atoms, copolymers of
ethylene with a vinyl aromatic monomer, such as ethylene/styrene
interpolymers; ethylene/propylene copolymers; copolymers of
ethylene with an alkane such as an ethylene/hexane copolymer;
thermoplastic polyurethanes (TPU's); and blends or mixtures
thereof, especially blends of polystyrene and an ethylene/styrene
interpolymer.
[0053] Other suitable polymers include polyvinyl chloride,
polycarbonates, polyamides, polyimides, polyesters such as
polyethylene terephthalate, polyester copolymers and modified
polyesters such as polyethylene terephthalate-glycol (PETG),
phenol-formaldehyde resins, thermoplastic polyurethanes (TPUs),
biodegradable polysaccharides such as starch, and polylactic acid
polymers and copolymers.
[0054] The polymer is preferably polyethylene (PE), polystyrene
(PS), polypropylene (PP), a blend of PS and an ethylene/styrene
interpolymer (ESI), a blend of ESI and PE, a blend of ESI and PP, a
blend of PS, PE and ESI or a blend of ESI with any one or more
polyolefin or ethylene/alpha-olefin copolymers, terpolymers or
interpolymers produced using a metallocene catalyst or a
constrained geometry catalyst (such as The Dow Chemical Company's
INSITE.RTM. catalysts, INSITE is a trademark of The Dow Chemical
Company). A more preferred polymer is PS.
[0055] Foamable polymer compositions can include additional
additives, such as those that are common for use in preparing blown
polymeric foam. Examples of suitable additional additives include
pigments, viscosity modifiers, flame retardants, infrared blockers
(such as those selected from a group consisting of carbon black,
graphite, gold, aluminum, and titanium dioxide), nucleating agents,
permeation modifiers, and extrusion aids. Additional additives
typically become dispersed within the polymer.
[0056] The present invention still further relates to a blown
polymeric foam containing residuals from the blowing agent
composition including a HFC(1) and CO.sub.2. The polymeric foam may
further contain additional blowing agents when they are included in
the blowing agent composition. One may identify the presence of a
HFC(1), CO.sub.2, and any additional blowing agents using standard
analytical techniques, such as gas chromatography. Polymeric foams
of the present invention are particularly useful as thermal
insulators.
[0057] Polymeric foams of the present invention may take any
physical configuration know in the art, such as sheet, plank, or
coalesced, parallel strands and sheets. The polymeric foam is
preferably a plank, more preferably a plank having a cross-section
of 30 square centimeters (cm.sup.2) or more and a cross-section
thickness in a minor dimension of 0.25 inch (6.4 millimeters (mm))
or greater, more preferably 0.375 inch (9.5 mm) or greater, and
still more preferably 0.5 inch (12.7 mm) or greater. A polymeric
foam having a minor dimension of up to 8 inches (200 mm) is
possible. The upper limit for the minor dimension is limited by
foaming equipment limitations. Given large enough equipment, a
minor dimension above 8 inches (200 mm) is conceivable.
[0058] Polymeric foams of the present invention preferably have a
density of 10 kilograms per cubic meter (kg/m.sup.3) or greater,
normally 25 kg/m.sup.3 or greater; and 100 kg/m.sup.3 or less,
normally 45 kg/m.sup.3 or less. Foams having a density below 10
kg/m.sup.3 generally lack a desired structural integrity. Polymeric
foam of the present invention may have a density up to, but not
including, that of a combination of the polymer and additives used
in preparing the foam.
[0059] Polymeric foam of the present invention can be open-celled
(having greater than 20% open-cell content) or close-celled (having
less than 20% open-cell content), but foam that has less than 10
percent open-celled content is preferable because it generally has
a lower thermal conductivity than a more open-celled foam. Measure
open-cell content according to American Society for Testing and
Materials (ASTM) method D2856-A. Typically, a polymeric foam of the
present invention has a thermal conductivity 90 days after
preparation (as determined according to standard method EN28301
using a sample temperature of 10.degree. C.) of 35 milliwatt per
meter-Kelvin (mW/m.multidot.K) or less, preferably 33
mW/m.multidot.K or less.
[0060] Polymeric foams of the present invention have an average
cell size greater than 0.05 millimeters (mm), preferably greater
than 0.075 mm, more preferably greater than 0.1 mm, and less than 2
mm, preferably less than 1.2 mm. Determine average cell size using
ATSM method D3576 with the following modifications: (1) image a
foam using optical or electron microscopy rather than projecting
the image on a screen; and (2) scribe a line of known length that
spans greater than 15 cells rather than scribing a 30 mm line.
[0061] The following examples further illustrate but do not limit
the scope of the invention. For the following examples, determine
density according to ASTM method D-1622, average cell size
according to ASTM method D-3576 with the earlier mentioned
modifications, open-cell content according to ASTM method D-2856,
and thermal conductivity according to standard method EN-28301
using a sample temperature of 10.degree. C. Measure thermal
conductivity values for each foam either 29 days after
manufacturing (29-day lambda) or 90 days after manufacturing
(90-day lambda), as indicated below. All pph values in the
Comparative Examples and Examples are weight parts per hundred
weight parts polymer resin.
[0062] Measure residual blowing agent in a foam using headspace
gas-chromatography. Place a 5 gram sample of foam in a vacuum oven,
purge with helium for 2-3 minutes, apply a vacuum, and then heat
the sample in the oven to 160.degree. C. while under vacuum. Inject
a sample of gas from the vacuum oven into a gas chromatograph
equipped with 2 different columns: (1) 5% SP 1200 plus 1.75%
Bentone on Chromosorb W-HP, and (2) Hayesep Q. The oven temperature
for the columns is 130.degree. C. The first column separates
volatile aromatic and unsaturated organics. The second column
separates carbon monoxide and carbon dioxide and air. Use a Type
Carle Series 400 detector to measure gas components through the
columns.
Comparative Example (Comp Ex) A: PS Foam Blown with Only Carbon
Dioxide
[0063] Melt 100 weight parts of PS resin (90 weight parts XZ40 PS
resin and 10 weight parts PS680 resin, both from The Dow Chemical
Company) in a 50 mm single screw extruder at 200.degree. C.
together with 2.8 parts per hundred (pph) hexabromocyclododecane,
0.15 pph copper phthalocyanine concentrate (20 wt % copper
phthalocyanine in PS resin), 0.2 pph barium stearate, 0.4 pph
linear low density polyethylene (DOWLEX.RTM. 2247A, DOWLEX is a
trademark of The Dow Chemical Company), and 0.15 pph
tetrasodiumpyrophosphate to form a polymer melt. XZ40 PS resin is a
has a weight average molecular weight (M.sub.w) of 151,000; a
polydispersity (M.sub.w/M.sub.n) of 3.1; and a melt flow index
(MFI) of 33 grams per 10 minutes (g/10 min). Determine MFI using
ASTM method D-1238 (190.degree. C., 5 kg load).
[0064] Inject 4.7 pph CO.sub.2 into the polymer melt at a pressure
of 164 bar (16.4 megapascals (MPa)) and mix. Cool to 125.degree. C.
and expand the polymer mix through a slit die (50 mm wide with a
0.8 mm opening) to atmospheric pressure, forming a 30 mm thick and
180 mm wide polymeric foam (Comp Ex A).
[0065] Properties for Comp Ex A are in Table 1, below.
Example (Ex) 1-3: PS Foam Blown with Carbon Dioxide and
HFC-365mfc
[0066] Prepare Ex 1-3 in a manner similar to Comp Ex A, using a
blowing agent composition consisting of CO.sub.2 and HFC-365mfc
(from Atofina) for the blowing agent. The concentration of CO.sub.2
and HFC-365mfc for each Ex is in Table 1. Maintain the total moles
of blowing agent per 100 grams of PS (mol/100 gPS) at 0.10-0.11 in
an effort to maintain a constant amount of blowing agent
molecules.
1TABLE 1 Comp Property Units Ex A Ex 1 Ex 2 Ex 3 CO.sub.2 wt % of
blowing agent 100 68 51 32 Concentration composition HFC - 365 mfc
wt % of blowing agent 0 32 49 68 Concentration composition Blowing
Agent pph based on PS 4.7 5.9 7.1 8.8 Composition Concentration
Total Blowing mol/100 gPS 0.11 0.11 0.11 0.10 Agent Residual HFC-
Wt % relative to PS 0 30 42 49 365 mfc 90 days resin weight after
manufacture Density kg/m.sup.3 41 40 38 38 Average Cell mm 0.2 0.2
0.2 0.3 Size Open-Cell percent 0.8 0.7 2.2 2.7 Content 90-Day
Lambda mW/m .multidot. K 36 34 33 31
[0067] Ex 1-3 illustrate that replacing CO.sub.2 with HFC-365mfc in
a blowing agent composition for PS foam produces a PS foam with
lower 90-day thermal conductivities than a similar foam blown with
only CO.sub.2 (Comp Ex A). Ex 1-3 also retain a measurable amount
of HFC-365mfc in the foam 90 days after manufacture.
[0068] Ex 3 further illustrates that a blowing agent composition
containing 32 wt % HFC-365mfc, an HFC(1), and 68 wt % CO.sub.2
produces a foam having a larger average cell size than a similar
foam prepared with only CO.sub.2 (Comp Ex A).
Comp Ex B: PS Foam Blown with Carbon Dioxide and HFC-134a
[0069] Prepare a foam in a manner similar to Comp Ex A except use a
blowing agent composition consisting of 70 wt % CO.sub.2 and 30 wt
% HFC-134a. The blowing agent composition comprises 5.9 pph of
blowing agent (based on PS weight) and 0.11 mol/100 gPS of blowing
agent. Foam properties for Comp Ex B are in Table 2, below.
Ex 4-6: PS Foam Blown with Carbon Dioxide, HFC-134a, and
HFC-365mfc
[0070] Prepare Ex 4-6 in a manner similar to Comp Ex B except
replace a portion of the CO.sub.2 and HFC-134a with HFC-365mfc.
Table 2 contains ratios each component in the blowing agent
composition along with foam parameters for each of Ex 4-6. Maintain
the total mol/100 gPS of blowing agent at 0.10-0.11 in an effort to
maintain a constant amount of blowing agent molecules.
[0071] Ex 4-6 illustrates that replacing CO.sub.2 and HFC-134a with
HFC-365mfc (an HFC with a boiling point of higher than 30.degree.
C.) in a blowing agent composition for PS foam produces PS with
lower 90-day thermal conductivities and larger average cell sizes.
Data in Table 2 for Ex 4-6 also illustrate that HFC-365mfc remains
in a PS foam longer than HFC-134a.
2TABLE 2 Comp Property Units Ex B Ex 4 Ex 5 Ex 6 CO.sub.2 wt % of
blowing 70 57 55 32 Concentration agent composition HFC-134a wt %
of blowing 30 31 14 0 Concentration agent composition HFC-365 mfc
wt % of blowing 0 12 31 68 Concentration agent composition Blowing
Agent pph based on PS 5.9 6.35 6.5 8.8 Composition Concentration
Total Blowing mol/100 gPS 0.11 0.11 0.10 0.10 Agent Residual HFC-
wt % relative to PS 23 26 7 0 134a 90 days resin weight after % of
original 77 85 50 -- manufacture loading Residual HFC- wt %
relative to PS 0 11 22 49 365 mfc 90 days resin weight after % of
original -- 92 71 72 manufacture loading Density kg/m.sup.3 48 47
36 38 Average Cell mm 0.15 0.22 0.19 0.26 Size Open-Cell percent 0
0 1 3 Content 90-Day Lambda mW/m .multidot. K 33 30 32 31
[0072] Ex 7-9: PS Blown with Carbon Dioxide and HFC-245fa Prepare
Ex 7-9 in a manner similar to Comp Ex A except use a blowing agent
composition consisting of CO.sub.2 and HFC-245fa. Table 3 contains
blowing agent composition ratios and foam properties for Ex 7-9 and
Comp Ex A.
3TABLE 3 Comp Property Units Ex A Ex 7 Ex 8 Ex 9 CO.sub.2 wt % of
blowing 100 81 66 57 Concentration agent composition HFC-245fa wt %
of blowing 0 19 34 43 Concentration agent composition Blowing Agent
pph based on PS 4.7 5.2 5.9 6.9 Composition Concentration Total
Blowing mol/100 gPS 0.11 0.1 0.1 0.1 Agent Residual HFC- wt %
relative to PS 0 6 19 24 245fa 90 days resin weight after
manufacture Density kg/m.sup.3 41 39 41 40 Average Cell mm 0.21
0.25 0.25 0.27 Size 90-Day Lambda mW/m .multidot. K 36 34 33 34
[0073] Ex 7-9 illustrate that partially replacing CO.sub.2 in a
blowing agent composition for PS foam with HFC-245fa, a HFC(1),
produces PS foam with a lower 90-day lambda and larger average cell
size.
[0074] Ex 7-9 further illustrate that HFC-245fa, a HFC(1), in
combination with CO.sub.2 produces a polymeric foam having a larger
average cell size relative to a foam prepared using only CO.sub.2
as a blowing agent.
Ex 11-12: PS Foam Blown with Carbon Dioxide, HFC-365mfc, and
HFC-245fa
[0075] Prepare Ex 11-12 in a manner similar to Comp Ex A accept use
a blowing agent composition consisting of CO.sub.2, HFC-365mfc, and
HFC-245fa. Table 5 contains blowing agent composition ratios and
foam properties for Comp Ex A and Ex 11-12.
[0076] Ex 11-12 illustrate that by partially replacing CO.sub.2
with HFC-365mfc and HFC-245fa in a blowing agent composition for PS
foam produces a PS foam having a lower 90-day lambda value than a
similar PS foam blown with only CO.sub.2 (Comp Ex A).
4TABLE 5 Property Units Comp Ex A Ex 11 Ex 12 CO.sub.2 wt % of
blowing 100 74 55 Concentration agent composition HFC-365mfc wt %
of blowing 0 17 30 Concentration agent composition HFC-245fa wt %
of blowing 0 9 15 Concentration agent composition Blowing Agent pph
based on PS 4.7 5.7 6.6 Composition Concentration Total Blowing
mol/100 gPS 0.1 0.1 0.1 Agent Residual HFC- Wt % relative to PS --
17 22 365mfc 90 days resin weight after manufacture Residual HFC-
Wt % relative to PS -- 0 1.5 245fa 90 days resin weight after
manufacture Density kg/m.sup.3 41 41 40 Average Cell mm 0.21 0.2
0.3 Size Open-Cell percent 0.83 1.0 2.3 Content 90-Day Lambda mW/m
.multidot. K 36 35 34
Ex 13-15: PS Foam using Blowing Agent Composition Comprising
Ethanol
[0077] Prepare Ex 13-15 in a manner similar to Comp Ex A except use
blowing agent compositions containing CO.sub.2, an HFC, and
ethanol. Table 6 contains blowing agent compositions and properties
for Ex 13-15.
5TABLE 6 Property Units Ex 13 Ex 14 Ex 15 CO.sub.2 wt % of blowing
51 51 53 Concentration agent composition HFC-365mfc wt % of blowing
21 26 0 Concentration agent composition HFC-245fa wt % of blowing
14 0 27 Concentration agent composition HFC-134a wt % of blowing 0
13 0 Concentration agent composition Ethanol wt % of blowing 14 10
20 Concentration agent composition Blowing Agent pph based on PS
7.1 7.65 7.4 Composition Concentration Total Blowing mol/100 gPS
0.12 0.13 0.14 Agent Residual HFC- Wt % relative to PS 14 23 0
365mfc 90 days resin weight after manufacture Residual HFC- Wt %
relative to PS 10 9 18 245fa 90 days resin weight after manufacture
Density kg/m.sup.3 33 35 34 Average Cell mm 0.27 0.17 0.25 Size
Open-Cell percent 1.5 0.9 0.6 Content 90-Day Lambda mW/m .multidot.
K 34 35 35
[0078] Ex 13-15 illustrate that low boiling alcohols, specifically
ethanol, can be part of a PS foam blowing agent composition along
with CO.sub.2 and one or more HFC having a boiling point of
14.degree. C. or higher and lower than 120.degree. C.
Comp Ex C: Carbon Black Containing Foam
[0079] Prepare Comp Ex C by melt-blending in a 64 mm single screw
extruder PS resin (M.sub.w of 168,000 and M.sub.w/M.sub.n of 2.44;
MFI of 11 g/10 min) with 5 pph of carbon black concentrate
(concentrate is 50% by weight AROSPERSE.RTM. carbon black in
polystyrene resin; AROSPERSE is a trademark of the J. M. Huber
Corporation and is available from Engineered Carbons, Inc.), 2.8
pph hexabromocyclododecane, 0.2 pph barium stearate, 0.2 pph DOWLEX
2247A linear low density polyethylene, and 0.15 pph
tetrasodiumpyrophosphate to form a polymer melt. All pph values are
relative to weight parts of PS resin (including both neat PS resin
and that in the carbon black concentrate). Heat the polymer melt to
200.degree. C. and inject 4.7 pph CO.sub.2. Cool the polymer melt
to 123.degree. C. and extrude through a slit die 50 mm wide having
a gap of 1.8 mm. The polymer melt fractures during extrusion when
forming to a 25 mm thick and 180 mm wide polymeric foam board.
Ex 16: Carbon Black with HFC-365mfc and CO.sub.2
[0080] Prepare Ex 16 as described for Comp Ex C using 0.11 mol/100
gPS of a blowing agent composition consisting of 39 wt % CO.sub.2
and 61 wt % HFC-365mfc (wt % based on blowing agent composition
weight). Extrude and form into a continuous board 25 mm thick and
180 mm wide. The resulting foam contains 2.5 pph carbon black, has
a density of 52 kg/m.sup.3, an open-cell content of 4.4%, and is
free from surface fractures.
[0081] Ex 16 illustrates, in light of Comp Ex C, that HFC-365mfc
can act as an aid in manufacturing a carbon black-containing PS
foam using a CO.sub.2 blowing agent composition in a formulation
and under condition that, in the absence of HFC-365mfc, fractures
during extrusion.
Comp Ex D, E, F, and G
[0082] Prepare Comp Ex D by melt-blending in a 64 mm single screw
extruder PS resin (M.sub.w of 168,000 and M.sub.w/M.sub.n of 2.44;
MFI of 11 g/10 min) with 15 pph carbon black concentrate (33 wt %
SEVACARB.RTM. MT-LS carbon black in the PS resin described;
SEVACARB is a trademark of Columbian Chemicals Company), 2.6 pph
hexabromocyclododecane, 0.2 pph barium stearate, 0.4 pph DOWLEX
2247A linear low density polyethylene, and 0.2 pph
tetrasodiumpyrophosphate to form a polymer melt. All pph are weight
parts relative to weight parts PS resin (including both neat PS
resin and that from the carbon black concentrate). Heat the polymer
melt to 200.degree. C. and inject 4.8 pph CO.sub.2. Cool the
polymer melt to 125.degree. C. and extrude through a slit die 50 mm
wide having a gap of about 1 mm to produce Comp Ex D.
[0083] Prepare Comp Ex E, F, and G with the same formulation,
processing equipment, and conditions as for Comp Ex D, but replace
a portion of the CO.sub.2 with HFC-134a. Table 7 shows the
concentrations of CO.sub.2 and HFC-134a for Comp Ex D-G.
Ex 17-19
[0084] Prepare Ex 17-19 with the same formulation, processing
equipment, and conditions as for Comp Ex D, replacing a portion of
the CO.sub.2 with HFC-365mfc at the same molar levels as the
HFC-134a in Comp Ex E, F, and G. Table 7 contains relative
concentrations of blowing agent components.
[0085] Comparing Comp Ex E-G with Comp Ex D, reveals little change
in any foam properties as HFC-134a replaces CO.sub.2. In contrast,
a comparison of Ex 17-19 with Comp Ex D, or with Comp Ex E-G,
reveals that the average open cell percent decreases dramatically
with use of HFC-365mfc. Lambda values are also lower in Ex 17-19
than in Comp Ex E-G.
6TABLE 7 Component/ Comp Comp Comp Comp Property Units Ex D Ex E Ex
F Ex G Ex 17 Ex 18 Ex 19 CO.sub.2 wt % of 100 75 59 42 67 50 33
total blowing agent HFC-134a wt % of 0 25 41 58 0 0 0 total blowing
agent HFC-134a mole 0 0.13 0.23 0.37 0 0 0 fraction of total
blowing agent HFC-365 mfc wt % of 0 0.0 0.0 0.0 33 50 67 total
blowing agent HFC-365 mfc mole 0 0 0 0 0.13 0.23 0.37 fraction of
total blowing agent Total Bowing pph 4.8 5.6 6.3 7.1 6.3 7.4 9.0
Agent Total Moles mol/100 g 0.11 0.11 0.11 0.11 0.11 0.11 0.11 of
Blowing PS Agent Foam Density kg/m.sup.3 42.5 42.8 43.6 42.9 43.3
42.6 42.9 Average cell mm 0.15 0.14 0.14 0.14 0.13 0.13 0.14 size
Average Open % 50.2 40.4 21.9 51.8 6.0 11.7 6.7 Cell 29 day mW/m *
K 32.0 31.3 30.9 31.9 30.4 30.4 27.0 lambda (AT 10.degree. c.)
[0086] Ex 17-19 illustrate that a liquid HFC facilitates
incorporation carbon black into a thermoplastic foam using a
CO.sub.2 blowing agent while achieving a lower open cell content
and a lower thermal conductivity than when using a blowing agent
containing CO.sub.2 alone or with HFC-134a.
[0087] One may expect results similar to those of Ex 1-19 for other
blowing agent compositions and polymer resins disclosed herein.
* * * * *