U.S. patent application number 17/677052 was filed with the patent office on 2022-06-09 for blowing agent compositions for insulating foams.
The applicant listed for this patent is Owens Corning Intellectual Capital, LLC. Invention is credited to Chase Boudreaux, S. Thomas Brammer, Yadollah Delaviz, Barbara Ann Fabian, Xiangmin Han, Jeffrey Thomas, Mitchell Zane Weekley.
Application Number | 20220177665 17/677052 |
Document ID | / |
Family ID | 1000006152794 |
Filed Date | 2022-06-09 |
United States Patent
Application |
20220177665 |
Kind Code |
A1 |
Boudreaux; Chase ; et
al. |
June 9, 2022 |
BLOWING AGENT COMPOSITIONS FOR INSULATING FOAMS
Abstract
Disclosed is a blowing agent composition comprising a
hydrofluoroolefins (HFO) and a branched hydrocarbon, and a foamable
polymer composition comprising the blowing agent composition. Also
disclosed is a method of making a polymer foam utilizing a blowing
agent composition comprising an HFO and a branched hydrocarbon.
Inventors: |
Boudreaux; Chase; (Canton,
OH) ; Delaviz; Yadollah; (Lewis Center, OH) ;
Han; Xiangmin; (Ravenna, OH) ; Brammer; S.
Thomas; (Kent, OH) ; Fabian; Barbara Ann;
(Medina, OH) ; Weekley; Mitchell Zane; (Tallmadge,
OH) ; Thomas; Jeffrey; (Mogadore, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Owens Corning Intellectual Capital, LLC |
Toledo |
OH |
US |
|
|
Family ID: |
1000006152794 |
Appl. No.: |
17/677052 |
Filed: |
February 22, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16425359 |
May 29, 2019 |
|
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17677052 |
|
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62677248 |
May 29, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J 2203/182 20130101;
C08J 2203/14 20130101; C08J 9/149 20130101; C08J 2325/06 20130101;
C08J 9/141 20130101; C08J 2201/03 20130101; C08J 2203/06 20130101;
C08J 2203/162 20130101; C08J 9/146 20130101 |
International
Class: |
C08J 9/14 20060101
C08J009/14 |
Claims
1. A foamable polymer composition comprising: a matrix polymer
composition comprising polystyrene; and a blowing agent composition
comprising: from 1 to 5 wt. % of a hydrofluoroolefin (HFO) blowing
agent comprising HFO-1234ze; from 0.05 to 1 wt. % of a branched
hydrocarbon blowing agent; and from 0.05 to 5 wt. % of a
hydrofluorocarbon (HFC) blowing agent, wherein the foamable polymer
composition contains essentially no water, and wherein each wt. %
is based upon the total weight of the foamable polymer
composition.
2. The foamable polymer composition of claim 1, wherein the blowing
agent composition consists of the HFO blowing agent, the branched
hydrocarbon blowing agent, and the HFC blowing agent.
3. The foamable polymer composition of claim 1, wherein the
branched hydrocarbon blowing agent is selected from the group
consisting of: isobutane; isopentane; neopentane; isohexane;
3-methylpentane; 2,3-dimethylbutane; neohexane; isoheptane;
3-methylhexane; 2,2-dimethylpentane; 2,3-dimethylpentane;
2,4-dimethylpentane; 3,3-dimethylpentane; 3-ethylpentane;
2,2,3-trimethylbutane; and combinations thereof.
4. The foamable polymer composition of claim 3, wherein the
branched hydrocarbon blowing agent consists of isobutane.
5. The foamable polymer composition of claim 1, wherein: the HFO
blowing agent consists of HFO-1234ze; the branched hydrocarbon
blowing agent consists of isobutane; and the HFC blowing agent
consists of 1,1-difluoroethane.
6. The foamable polymer composition of claim 1, wherein the
foamable composition comprises less than 0.03 moles HFO blowing
agent per 100 grams of matrix polymer.
7. A foamable polymer composition comprising: a matrix polymer
composition comprising polystyrene; and a blowing agent composition
comprising: from 1 to 5 wt. % of a hydrofluoroolefin (HFO) blowing
agent comprising HFO-1234ze; from 0.05 to 1 wt. % of a branched
hydrocarbon blowing agent; and from 0.05 to 5 wt. % of a co-blowing
agent comprising carbon dioxide, wherein the foamable polymer
composition contains essentially no water, and wherein each wt. %
is based upon the total weight of the foamable polymer
composition.
8. The foamable polymer composition of claim 7, wherein the blowing
agent composition consists of the HFO blowing agent, the branched
hydrocarbon blowing agent, and the carbon dioxide.
9. The foamable polymer composition of claim 7, wherein the
branched hydrocarbon blowing agent is selected from the group
consisting of: isobutane; isopentane; neopentane; isohexane;
3-methylpentane; 2,3-dimethylbutane; neohexane; isoheptane;
3-methylhexane; 2,2-dimethylpentane; 2,3-dimethylpentane;
2,4-dimethylpentane; 3,3-dimethylpentane; 3-ethylpentane;
2,2,3-trimethylbutane; and combinations thereof.
10. The foamable polymer composition of claim 9, wherein the
branched hydrocarbon blowing agent consists of isobutane.
11. The foamable polymer composition of claim 7, wherein: the HFO
blowing agent consists of HFO-1234ze; the branched hydrocarbon
blowing agent consists of isobutane; and the co-blowing agent
consists of carbon dioxide.
12. The foamable polymer composition of claim 7, wherein the
foamable composition comprises less than 0.03 moles HFO blowing
agent per 100 grams of matrix polymer.
13. A method of manufacturing polymer foam, comprising: a)
providing a matrix polymer composition comprising polystyrene; b)
melting the matrix polymer composition in an extruder; c) injecting
a blowing agent composition comprising into the molten matrix
polymer composition within the extruder to form a foamable polymer
composition, wherein the blowing agent composition comprises: from
1 to 5 wt. % of a hydrofluoroolefin (HFO) blowing agent comprising
HFO-1234ze; from 0.05 to 1 wt. % of a branched hydrocarbon blowing
agent; and from 0.05 to 5 wt. % of a co-blowing agent comprising a
hydrofluorocarbon (HFC), carbon dioxide, or combinations thereof,
wherein each wt. % is based upon the total weight of the foamable
polymer composition, wherein the foamable polymer composition
contains essentially no water or carbon dioxide; and d) extruding
the foamable polymer composition to form a polymer foam.
14. The method of claim 13, wherein the polymer foam has an R value
from 4 to 7.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/425,359, filed on May 29, 2019, which claims priority to and
any benefit of U.S. Provisional Application No. 62/677,248, filed
on May 29, 2018, the entire contents of which are incorporated
herein by reference.
FIELD OF DISCLOSURE
[0002] This invention relates to blowing agent compositions for
insulating foams made from thermoplastic polymers. This invention
further relates to insulating foams made utilizing these blowing
agent compositions.
BACKGROUND OF THE INVENTION
[0003] In the past, insulating foams have been made utilizing
halogenated blowing agents to create gas-filled cells within the
insulating foams. Chlorofluorocarbons (CFCs) and
chlorofluorohydrocarbons (HCFCs) were among the earliest blowing
agents. However, suspected environmental concerns about chlorinated
blowing agents, including possible ozone depletion in the upper
atmosphere, led to the development of blowing agents that were
considered less damaging to the environment. These later blowing
agents included fluorocarbons (FCs) and fluorohydrocarbons
(HFCs).
[0004] Recently, newer hydrofluoroolefins (HFOs) have been
developed. HFO blowing agents are believed to be more
environmentally friendly than traditional halogenated blowing
agents. For example, HFOs ae believed to have reduced Ozone
Depletion Potential (ODP) and reduced Global Warming Potential
(GWP) compared to traditional FC and HFC halogenated blowing
agents.
[0005] Other than halogenated blowing agents, other types of
blowing agents have been investigated. For example, hydrocarbons
such as pentane, hexane, cyclopentane and similar compounds have
also been considered as blowing agents. These hydrocarbons are
highly flammable and volatile, thereby raising both safety concerns
and concerns about the emission of volatile organic compounds
(VOCs). Carbon dioxide (CO.sub.2) is an attractive candidate as a
blowing agent, from both the environmental and economic
standpoints. Successfully using CO.sub.2 as a blowing agent is
challenging due to the relatively low solubility, high diffusivity
and poor processability of CO.sub.2 in the polymers typically used
as the matrix polymers of insulating foams. CO.sub.2 also has an
increased thermal conductivity relative to that of HCFCs and HFCs,
with CO.sub.2-blown foam exhibiting about 10-20% lower insulation
values than corresponding foams produced with HCFCs or HFCs.
[0006] To ensure that an insulating foam has the desired properties
(e.g., low density, good thermal resistance, etc.), it is important
that the blowing agent be sufficiently soluble in the polymer
matrix of the insulating foam. It has been found that HFO blowing
agents alone may not be sufficiently soluble in the polymer matrix
of the insulating foam, resulting in insulating foams that are too
dense or which allow unacceptably high thermal conductivity. To
improve the properties of the resulting insulating foam, blowing
agent compositions containing combinations of HFOs with HCFCs,
HFCs, carbon dioxide, water, and other such mixtures have been
attempted, with mixed results.
SUMMARY OF THE INVENTION
[0007] The objectives of the present invention include improved
blowing agent compositions comprising an HFO and a branched
hydrocarbon. The objectives further include a foamable polymer
composition incorporating the improved blowing agent, and an
improved method of making polymer foams using the improved blowing
agent.
[0008] In an exemplary embodiment of the invention, a blowing agent
composition is provided comprising a hydrofluoroolefin (HFO) and a
branched hydrocarbon. In some exemplary embodiments, the blowing
agent contains essentially no water.
[0009] In an exemplary embodiment of the invention, a foamable
polymer composition is provided comprising a matrix polymer and a
blowing agent composition comprising an HFO and a branched
hydrocarbon. In some exemplary embodiments, the foamable polymer
composition contains essentially no water.
[0010] In an exemplary embodiment of the invention, a method of
manufacturing a polymer foam is provided, comprising: melting a
matrix polymer; mixing a blowing agent composition comprising an
HFO and a branched hydrocarbon with the matrix polymer melt to form
a foamable polymer composition; and extruding the foamable polymer
composition to form a polymer foam. In some exemplary embodiments,
the foamable polymer composition contains essentially no water.
DESCRIPTION OF THE DRAWINGS
[0011] Example embodiments of the invention will be apparent from
the more particular description of certain example embodiments of
the invention provided below and as illustrated in the accompanying
drawings.
[0012] FIG. 1 is a graph of the thermal insulating properties for
foam formulations comprising various blowing agent compositions
after 7 days aging.
[0013] FIG. 2 is a graph of thermal insulating properties for foam
formulations containing various concentrations of HFO-1234ze and
n-pentane as the foams age.
[0014] FIG. 3 is a graph of thermal insulating properties for foam
formulations containing HFO-1234ze and various co-blowing agents as
the foams age.
[0015] FIG. 4 is a graph of the data in FIG. 3 normalized for the
mole % concentration of each co-blowing agent.
[0016] FIG. 5 is a graph of thermal insulating properties for foam
formulations containing HFO-1234ze and isobutane at various
densities as the foams age.
[0017] FIG. 6 is a graph of thermal insulating properties of foam
formulations containing HFO-1234ze and various hydrocarbon
co-blowing agents at various densities after 7 days aging.
[0018] FIG. 7 is a graph of thermal insulating properties for foam
formulations containing HFO-1234ze, isobutane, and carbon
dioxide.
[0019] These drawings have been provided to assist in the
understanding of the example embodiments of the invention as
described in more detail below and should not be construed as
unduly limiting the invention.
DETAILED DESCRIPTION
[0020] A polymer foam composition, along with a method for making
polymer foam, is described in detail herein. The composition and
method for making polymer foam disclosed herein includes blowing
agent composition comprising a hydrofluoroolefin (HFO) and a
branched hydrocarbon. In some exemplary embodiments, the blowing
agent contains essentially no water or carbon dioxide. The
resulting polymer foam has reduced thermal conductivity, and
therefore improved insulation properties, when compared to blowing
agents comprising HFO and linear hydrocarbons. These and other
features of the polymer foam, as well as some of the many optional
variations and additions, are described in detail hereafter.
[0021] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs. Any
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention. Any references cited herein, including published or
corresponding U.S. or foreign patent applications, issued U.S. or
foreign patents, or any other references, are each incorporated by
reference in their entireties, including all data, tables, figures,
and text presented in the cited references.
[0022] As used in the description of the invention and the appended
claims, the singular forms "a," "an," and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. To the extent that the term "includes" or
"including" is used in the specification or the claims, it is
intended to be inclusive in a manner similar to the term
"comprising" as that term is interpreted when employed as a
transitional word in a claim. Furthermore, to the extent that the
term "or" is employed (e.g., A or B) it is intended to mean "A or B
or both." When the applicants intend to indicate "only A or B but
not both" then the term "only A or B but not both" will be
employed. Thus, use of the term "or" herein is the inclusive, and
not the exclusive use.
[0023] Numerical ranges as used herein are intended to include
every number and subset of numbers within that range, whether
specifically disclosed or not. Further, these numerical ranges
should be construed as providing support for a claim directed to
any number or subset of numbers in that range. For example, a
disclosure of from 1 to 10 should be construed as supporting a
range of from 2 to 8, from 3 to 7, from 5 to 6, from 1 to 9, from
3.6 to 4.6, from 3.5 to 9.9, and so forth.
[0024] All references to singular characteristics or limitations of
the present disclosure shall include the corresponding plural
characteristic or limitation, and vice versa, unless otherwise
specified or clearly implied to the contrary by the context in
which the reference is made.
[0025] As used herein, unless specified otherwise, the values of
the constituents or components of the polymer foam, the flame
retardant composition, or other compositions are expressed in
weight percent or % by weight of each ingredient in the
composition. The values provided include up to and including the
endpoints given. Unless otherwise specified, the terms "% by
weight" and "wt. %" are used interchangeably and are meant to
indicate a percentage based on 100% of a total weight. In some
embodiments, the amount of blowing agent(s) is given in terms of
moles/100 g, which is meant to indicate the number of moles of the
specified blowing agent per 100 grams of matrix polymer.
[0026] As used herein, the term "polymer" is generic to the terms
"homopolymer," "copolymer," "terpolymer," and combinations of
homopolymers, copolymers, and/or terpolymers.
[0027] As used herein, the term "matrix polymer" refers to the
polymer or polymer mixture forming the bulk of the foamable polymer
composition and the polymer foam product. The matrix polymer
provides strength, flexibility, toughness, and durability to the
final product.
[0028] As used herein, the term "matrix polymer composition" refers
to a composition comprising the matrix polymer(s) with other
optional additives, such as stabilizers, processing aids,
colorants, fire retardants, etc.
[0029] As used herein, the term "blowing agent" refers to a liquid
or gaseous compound or mixture which, when mixed with a molten
matrix polymer composition under pressure (such as the pressure
within an extruder), forms a foamable polymer composition, and
which converts to tiny pockets of gas when the composition is
released from pressure, thereby causing the foamable polymer
composition to foam. As used herein, the term "co-blowing agent"
refers to a second (third, fourth, etc.) blowing agent in a blowing
agent composition.
[0030] As used herein, the term "branched hydrocarbon" refers to a
compound consisting of carbon and hydrogen atoms, where the carbon
atoms are arranged in a branched rather than a linear or cyclic
conformation. Exemplary branched hydrocarbons include isobutane,
isopentane, neopentane, isohexane, 3-methylpentane,
2,3-dimethylbutane, neohexane, isoheptane, 3-methylhexane,
2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane,
3,3-dimethylpentane, 3-ethylpentane, and 2,2,3-trimethylbutane.
[0031] The general procedure utilized in the preparation of
extruded synthetic foam bodies generally includes the steps of
melting a matrix polymer composition, then incorporating a blowing
agent composition into the polymer melt to form a foamable polymer
composition, under conditions that provide for the thorough mixing
of the blowing agent composition and the matrix polymer while
preventing the foamable polymer composition from foaming
prematurely, e.g., under pressure. Other additives (e.g.,
stabilizers, processing aids, colorants, fire retardants, etc.) may
also be added into the foamable polymer composition. This foamable
polymer composition is then typically extruded through a single or
multi-stage extrusion die to cool and reduce the pressure on the
foamable polymer composition, allowing the foamable polymer
composition to foam and produce a foamed product. As will be
appreciated, the relative quantities of the polymer(s), blowing
agent(s) and additives in the foamable polymer composition, as well
as the temperature and the manner in which the pressure is reduced,
may affect the qualities and properties of the resulting foam
product.
Blowing Agent Composition
[0032] In selecting a blowing agent composition, the solubility of
the blowing agent composition in the matrix polymer is an important
consideration. For example, the combination of pentane and a CFC
such as Freon 11 and 12 is partially soluble in PS and has been
used for generating PS foams that exhibited a generally acceptable
appearance and physical properties such as surface finish, cell
size and distribution, orientation, shrinkage and stiffness.
Fluorocarbons (FCs) and hydrofluorocarbons (HFCs), such as
1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1-difluoroethane
(HFC-152a), are thought to be much more ozone friendly than CFCs,
but they tend to be less soluble in PS. Newer hydrofluoroolefin
(HFO) blowing agents are believed to be more environmentally
friendly than traditional halogenated blowing agents. However, many
HFOs, such as tetrafluoropropenes, have poor solubility in PS. When
these HFOs are used as blowing agents without a co-blowing agent to
make PS foam, the HFO tends to remain undissolved in the PS matrix,
which creates large blow-holes and other defects in the foam
product during the extrusion of the foamable polymer composition.
The poor solubility of HFO blowing agents in PS may also
detrimentally impact the long-term insulating properties of the
foam.
[0033] HFO blowing agents with co-blowing agents, such as
hydrocarbons, hydrofluorocarbons, carbon dioxide, and water, have
been studied to determine if the co-blowing agents improve the
solubility of HFO in the matrix polymer. Hydrocarbons are soluble
in PS, and are thought to improve the solubility of HFO in PS as
well.
[0034] The inventors have discovered that HFO blowing agent
compositions with branched hydrocarbon co-blowing agents
unexpectedly form foams with improved insulating properties, when
compared to foams made with blowing agent compositions comprising
HFO with linear hydrocarbons, cyclic hydrocarbons, or HFC
co-blowing agents, excluding branched hydrocarbons. Without wishing
to be bound by theory, the inventors believe that branched
hydrocarbons are superior co-blowing agents because of the
compactness of the branched hydrocarbon molecule. The pendant
branched groups (e.g., methyl groups) on branched hydrocarbons
means that these molecules are more compact and have a smaller
surface area than do the molecules of linear or cyclic hydrocarbons
with the same number of carbon atoms. The intermolecular attractive
forces, which depend on the surface area of a molecule, are also
smaller between branched hydrocarbons than between linear or cyclic
hydrocarbons with the same number of carbon atoms. Consequently,
the boiling points of branched hydrocarbons are less than the
corresponding linear or cyclic hydrocarbons, and the lower boiling
points result in higher vapor pressure for the branched
hydrocarbons. The higher vapor pressure of the branched
hydrocarbons leads to more branched hydrocarbon gas in each cell of
the insulating foam. Because a blowing agent must be in gaseous
form to be an effective insulating gas, blowing agents with higher
vapor pressures, and therefore more gas in the foam cells, tend to
have improved insulating properties.
[0035] The hydrofluoroolefin blowing agent in the blowing agent
composition of the present invention may include, for example,
3,3,3-trifluoropropene (HFO-1243zf); 2,3,3-trifluoropropene; (cis
and/or trans)-1,3,3,3-tetrafluoropropene (HFO-1234ze), particularly
the trans isomer; 1,1,3,3-tetrafluoropropene;
2,3,3,3-tetrafluoropropene (HFO-1234yf); (cis and/or
trans)-1,2,3,3,3-pentafluoropropene (HFO-1225ye);
1,1,3,3,3-pentafluoropropene (HFO-1225zc);
1,1,2,3,3-pentafluoropropene (HFO-1225yc); hexafluoropropene
(HFO-1216); 2-fluoropropene, 1-fluoropropene; 1,1-difluoropropene;
3,3-difluoropropene; 4,4,4-trifluoro-1-butene;
2,4,4,4-tetrafluoro-1-butene; 3,4,4,4-tetrafluoro-1-butene;
octafluoro-2-pentene (HFO-1438);
1,1,3,3,3-pentafluoro-2-methyl-1-propene; octafluoro-1-butene;
2,3,3,4,4,4-hexafluoro-1-butene; 1,1,1,4,4,4-hexafluoro-2-butene
(HFO-1336m/z); 1,2-difluoroethene (HFO-1132);
1,1,1,2,4,4,4-heptafluoro-2-butene; 3-fluoropropene,
2,3-difluoropropene; 1,1,3-trifluoropropene;
1,3,3-trifluoropropene; 1,1,2-trifluoropropene; 1-fluorobutene;
2-fluorobutene; 2-fluoro-2-butene; 1,1-difluoro-1-butene;
3,3-difluoro-1-butene; 3,4,4-trifluoro-1-butene;
2,3,3-trifluoro-1-butene; 1, 1,3,3-tetrafluoro-1-butene;
1,4,4,4-tetrafluoro-1-butene; 3,3,4,4-tetrafluoro-1-butene;
4,4-difluoro-1-butene; 1,1,1-trifluoro-2-butene;
2,4,4,4-tetrafluoro-1-butene; 1,1,1,2-tetrafluoro-2 butene;
1,1,4,4,4-pentafluoro-1-butene; 2,3,3,4,4-pentafluoro-1-butene;
1,2,3,3,4,4,4-heptafluoro-1-butene;
1,1,2,3,4,4,4-heptafluoro-1-butene; and
1,3,3,3-tetrafluoro-2-(trifluoromethyl)-propene. In some exemplary
embodiments, the blowing agent or co-blowing agents include
HFO-1234ze.
[0036] The branched hydrocarbon co-blowing agent in the blowing
agent composition of the present invention may include, for
example, branched butanes, pentanes, hexanes, and heptanes.
Preferred branched hydrocarbon co-blowing agents include, but are
not limited to, isobutane, isopentane, neopentane, isohexane,
3-methylpentane, 2,3-dimethylbutane, neohexane, isoheptane,
3-methylhexane, 2,2-dimethylpentane, 2,3-dimethylpentane,
2,4-dimethylpentane, 3,3-dimethylpentane, 3-ethylpentane, and
2,2,3-trimethylbutane. In some exemplary embodiments, the blowing
agent or co-blowing agents include isobutane, isopentane, or
combinations thereof.
[0037] In certain exemplary embodiments, the HFO blowing agent
comprises from about 14% to about 89% by weight of the total weight
of the blowing agent composition, including from about 15% to about
80%, including from about 20% to about 75%, including from about
25% to about 70%, including from about 30% to about 65%, including
from about 35% to about 60%, and including from about 38% to about
55% by weight of the total weight of the blowing agent composition.
In some exemplary embodiments, the HFO blowing agent comprises less
than 50% by weight of the total blowing agent composition.
[0038] In certain exemplary embodiments, the branched hydrocarbon
co-blowing agent comprises from about 5.0% to about 85% by weight
of the total weight of the blowing agent composition, including
from about 7.0% to about 50%, including from about 9.0% to about
45%, including from about 10% to about 40%, including from about
12% to about 35%, including from about 12.3% to about 32%,
including about 12.5% to about 30%.
[0039] In certain exemplary embodiments, the blowing agent
composition further includes at least one secondary co-blowing
agent, such as one or more hydrofluorocarbons ("HFC"),
hydrochlorofluorocarbons ("HCFO"), carbon dioxide, and water. In
some exemplary embodiments, the blowing agent composition includes
two or more secondary co-blowing agents, such as a
hydrofluorocarbon and carbon dioxide. In some exemplary
embodiments, the blowing agent composition is free of a secondary
co-blowing agent. In some exemplary embodiments, the blowing agent
formulation is free of carbon dioxide and/or water. In various
exemplary embodiments, the blowing agent composition is free of a
hydrofluorocarbon.
[0040] In some exemplary embodiments, the secondary co-blowing
agent may comprise one or more hydrofluorocarbons. The specific
hydrofluorocarbon utilized is not particularly limited. A
non-exhaustive list of examples of suitable blowing HFC blowing
agents include 1,1-difluoroethane (HFC-152a),
1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,2,2-tetrafluoroethane
(HFC-134), 1,1,1-trifluoroethane (HFC-143a), difluoromethane
(HFC-32), 1,3,3,3-pentafluoropropane (HFO-1234ze),
pentafluoro-ethane (HFC-125), fluoroethane (HFC-161),
1,1,2,2,3,3-hexafluoropropane (HFC-236ca),
1,1,1,2,3,3-hexafluoropropane (HFC-236ea),
1,1,1,3,3,3-hexafluoropropane (HFC-236fa),
1,1,1,2,2,3-hexafluoropropane (HFC-245 ca),
1,1,2,3,3-pentafluoropropane (HFC-245 ea), 1,1,1,2,3
pentafluoropropane (HFC-245 eb), 1,1,1,3,3-pentafluoropropane
(HFC-245fa), 1,1,1,4,4,4-hexafluorobutane (HFC-356mff),
1,1,1,3,3-pentafluorobutane (HFC-365mfc), and combinations thereof.
In some exemplary embodiments, the secondary co-blowing agent
comprises HFC-152a.
[0041] The secondary co-blowing agent may also comprise one or more
hydrochlorofluoroolefins (HCFO), such as HCFO-1233;
1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124);
1,1-dichloro-1-fluoroethane (HCFC-141b); 1, 1,1,2-tetrafluoroethane
(HFC-134a); 1,1,2,2-tetrafluoroethane (HFC-134);
1-chloro-1,1-difluoroethane (HCFC-142b);
1,1,1,3,3-pentafluorobutane (HFC-365mfc);
1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea); tnchlorofluoromethane
(CFC-11); dichlorodifluoromethane (CFC-12); and
dichlorofluoromethane (HCFC-22).
[0042] The term "HCFO-1233" is used herein to refer to all
trifluoromonochloropropenes. Among the trifluoromonochloropropenes
are included both cis- and trans-1,1,1-trifluo-3,chlororopropene
(HCFO-1233zd or 1233zd). The term "HCFO-1233zd" or "1233zd" is used
herein generically to refer to 1,1,1-trifluo-3-chloro-propene,
independent of whether it is the cis- or trans-form. The terms "cis
HCFO-1233zd" and "trans HCFO-1233zd" are used herein to describe
the cis- and trans-forms or trans-isomer of
1,1,1-trifluo,3-chlororopropene, respectively.
[0043] In certain exemplary embodiments, the secondary co-blowing
agent comprises from 0 to about 90% by weight off the blowing agent
composition, including about 0.5% to about 89% by weight of the
total weight of the blowing agent composition, including from about
1% to about 50%, including from about 3% to about 25%, including
from about 5% to about 20%, including from about 7% to about 15%,
and including from about 7.5% to about 13% by weight of the total
weight of the blowing agent composition.
[0044] In certain exemplary embodiments, the total blowing agent
composition is present in an amount from about 2% to about 15% by
weight, and in some embodiments, from about 3% to about 10% by
weight, or from about 4% to about 9% by weight (based upon the
total weight of the foamable composition, excluding the blowing
agent composition). In some exemplary embodiments, the total
blowing agent composition is present in an amount from about 6.8 to
about 8.0% by weight, including about 7.3 to about 7.9% by weight,
based on the total weight of the foamable composition, excluding
the blowing agent composition.
[0045] In certain exemplary embodiments, the HFO blowing agent
comprises from about 1% to about 8% by weight of the total weight
of all ingredients in the foamable composition, including from
about 1.5% to about 7.5%, including from about 2% to about 7%,
including from about 2.5% to about 6.5%, including from about 3% to
about 6%, including from about 3.5% to about 5.5%, including from
about 4% to about 5%, and including about 4.5% by weight of the
total weight of all ingredients in the foamable composition.
[0046] In certain exemplary embodiments, the HFO comprises from
about 0.004 moles/100 g to about 0.140 moles/100 g of the matrix
polymer, including from about 0.007 moles/100 g to about 0.125
moles/100 g, including from about 0.009 moles/100 g to about 0.120
moles/100 g, including from about 0.010 moles/100 g to about 0.108
moles/100 g, including from about 0.015 moles/100 g to about 0.0999
moles/100 g, including from about 0.017 moles/100 g to about 0.091
moles/100 g, including from about 0.019 moles/100 g to about 0.085
moles/100 g, and including about 0.020 to about 0.075 moles/100 g
of the matrix polymer. In some exemplary embodiments, the HFO
blowing agent comprises less than 0.05 moles/100 grams of matrix
polymer, including less than 0.045 moles/100 g, less than about
0.03 moles/100 g, less than 0.025 moles/100 g, less than 0.023
moles/100 grams, and 0.021 moles/100 grams matrix polymer.
[0047] In certain exemplary embodiments, the branched hydrocarbon
co-blowing agent comprises from about 0.05% to about 6% by weight
of the total weight of all ingredients in the foamable composition,
including from about 0.1% to about 5.5%, including from about 0.5%
to about 5%, including from about 0.8% to about 4.5%, including
from about 0.9% to about 4%, and including about 1.0% by weight of
the total weight of all ingredients. In certain exemplary
embodiments, the branched hydrocarbon co-blowing agent comprises
from about 0.0005 moles/100 g to about 0.150 moles/100 g of the
matrix polymer, including from about 0.0010 mole/100 g to about
0.10 moles/100 g, including from about 0.0050 moles/100 g to about
0.085 moles/100 g, including from about 0.0080 moles/100 g to about
0.078 moles/100 g, including from about 0.009 moles/100 g to about
0.065 moles/100 g, and including about 0.0100 to about 0.020
moles/100 g of the matrix polymer.
[0048] In certain exemplary embodiments, the one or more secondary
co-blowing agent comprises from about 0.05% to about 6% by weight
of the total weight of all ingredients, in the foamable
composition, including from about 0.1% to about 5.5%, including
from about 0.5% to about 5%, including from about 0.8% to about
4.5%, including from about 0.9% to about 4%, and including about
1.0% by weight of the total weight of all ingredients.
Matrix Polymer
[0049] The matrix polymer forms the bulk of the foamable polymer
mixture and provides strength, flexibility, toughness, and
durability to the final product. The matrix polymer is not
particularly limited, and generally, any polymer capable of being
foamed may be used as the matrix polymer in the foamable polymer
mixture. The matrix polymer may be a thermoplastic or thermoset
polymer. In some embodiments, the matrix polymer may comprise a
single polymer. In some embodiments, the matrix polymer may
comprise a blend of two or more polymers. In some embodiments, the
matrix polymer may be selected to provide sufficient mechanical
strength to the final polymer foamed product. In some embodiments,
the matrix polymer may be selected to be compatible with the
process utilized to form final polymer foam product. In some
embodiments, the matrix polymer is chemically stable, that is,
generally non-reactive, within the expected temperature range
experienced by the matrix polymer during formation and subsequent
use in a polymer foam.
[0050] The matrix polymer may be present in the foamable polymer
mixture in an amount from at least about 50 wt. % (based on the
total weight of all ingredients excluding the blowing agent
composition), in an amount from about 60 wt. % to about 100 wt. %,
in an amount from about 70 wt. % to about 99 wt. %, in an amount
from about 75 wt. % to about 98 wt. %, in an amount from about 80
wt. % to about 96 wt. %, or in an amount from about 85 wt. % to
about 95 wt. %. In certain exemplary embodiments, the matrix
polymer may be present in an amount from about 80 wt. % to about
100 wt. %.
[0051] Non-limiting examples of suitable matrix polymers include
alkenyl aromatic polymers, styrenic polymers, polystyrene (PS),
styrenic copolymers, styrenic block copolymers, copolymers of
styrene and butadiene, styrene acrylonitrile (SAN), acrylonitrile
butadiene styrene, acrylic/styrene/acrylonitrile block terpolymer
(ASA), styrene maleic anhydride copolymer (SMA), styrene methyl
methacrylate copolymer (SMMA), polyolefins, polyethylene (PE),
polypropylene (PP), copolymers of ethylene and propylene,
copolymers of vinyl acetate and ethylene, polyvinyl chloride (PVC),
chlorinated polyvinyl chloride (CPVC), polycarbonates,
polyisocyanurates, polyesters, polyethylene terephthalate (PET),
polyacrylic acid esters, polymethylmethacrylate (PMMA),
polyphenylene oxide, polyurethanes, phenolics, polysulfone,
polyphenylene sulfide, acetal resins, polyamides, polyaramides,
polyimides, polyetherimides, rubber modified polymers,
thermoplastic polymer blends, and combinations thereof.
[0052] In some exemplary embodiments, the matrix polymer is an
alkenyl aromatic polymer material. Suitable alkenyl aromatic
polymer materials include alkenyl aromatic homopolymers and
copolymers of alkenyl aromatic compounds and copolymerizable
ethylenically unsaturated co-monomers. In addition, the alkenyl
aromatic polymer material may include minor proportions of
non-alkenyl aromatic polymers. The alkenyl aromatic polymer
material may be formed of one or more alkenyl aromatic
homopolymers, one or more alkenyl aromatic copolymers, a blend of
one or more of each of alkenyl aromatic homopolymers and
copolymers, or blends thereof with a non-alkenyl aromatic
polymer.
[0053] Examples of alkenyl aromatic polymers include, but are not
limited to, those alkenyl aromatic polymers derived from alkenyl
aromatic compounds such as styrene, styrene acrylonitrile (SAN)
copolymers, alpha-methyl styrene, ethylstyrene, vinyl benzene,
vinyl toluene, chlorostyrene, and bromostyrene. In at least one
embodiment, the alkenyl aromatic polymer comprises polystyrene
(PS).
[0054] In certain exemplary embodiments, minor amounts of
monoethylenically unsaturated monomers such as C2 to C6 alkyl acids
and esters, ionomeric derivatives, and C4 to C8 dienes may be
copolymerized with alkenyl aromatic monomers to form the alkenyl
aromatic polymer. Non-limiting examples of copolymerizable monomers
include acrylic acid, methacrylic acid, ethacrylic acid, maleic
acid, itaconic acid, acrylonitrile, maleic anhydride, methyl
acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate,
methyl methacrylate, vinyl acetate, and butadiene.
[0055] In certain exemplary embodiments, the matrix polymer may be
formed entirely of polystyrene. In certain exemplary embodiments,
the matrix polymer may be formed substantially of (e.g., greater
than 95 wt. %) of polystyrene. In certain exemplary embodiments,
the matrix polymer may be formed of from about 40-100 wt. % of
polystyrene, including from about 45-99 wt. %, including from about
50-98 wt. %, including from about 55-97 wt. %, including from about
60-96 wt. %, including from about 65-95 wt. %, including from about
70-94 wt. %, including from about 75-93 wt. %, including from about
80-92 wt. %, including from about 85-91 wt. %, including from about
80-90 wt. % of polystyrene.
[0056] In certain exemplary embodiments, the polymer foam may
comprise at least one optional additive including, but not limited
to, antioxidants, thermal stabilizers, UV stabilizers, acid
scavengers, flame retardant compositions, synergists, nucleating
agents, plasticizing agents, pigments, elastomers, processing
agents, extrusion aids, fillers, antistatic agents, biocides,
termite-ocides, colorants, oils, or waxes. In certain exemplary
embodiments, the polymer foam may comprise a mixture of additives.
These optional additives may be included in amounts necessary to
obtain desired characteristics of the foamable polymer mixture or
resultant polymer foam. The additives may be added to the foamable
polymer mixture, or they may be incorporated before, during, or
after the polymerization process used to make the matrix
polymer.
[0057] In certain exemplary embodiments, the polymer foam includes
one or more processing aids, such as a carbonate composition.
Exemplary carbonate compositions include propylene carbonate,
dimethyl carbonate, butylene carbonate, ethylene carbonate, and the
like. The one or more processing aids may be included in the
polymer foam material in an amount from 0 to 20% by weight,
including about 0.05 to about 17% by weight, about 0.1 to about 15%
by weight, about 1.0 to about 10% by weight, about 1.5 to about 8%
by weight, and about 2 to about 5% by weight.
Methods of Manufacture
[0058] Polymer foams comprising the blowing agent composition may
be extruded foams or expanded foams. These polymer foams may be
made by modifying known manufacturing methods using typical
manufacturing equipment.
[0059] In some embodiments, the polymer foams of the present
disclosure are extruded polymer foams made by an extrusion method.
The extrusion apparatus may comprise a single or twin screw
extruder including a barrel surrounding a screw on which a spiral
flight is provided, configured to compress, and thereby, heat and
melt the material introduced into the screw extruder. The matrix
polymer and optional additives form a matrix polymer mixture, which
may be fed into the screw extruder as a flowable solid, such as
beads, granules, or pellets, or as a liquid or semi-liquid melt,
from one or more feed hoppers.
[0060] As the matrix polymer mixture advances through the screw
extruder, the decreasing spacing of the flight defines a
successively smaller space through which the matrix polymer mixture
is forced by the rotation of the screw. This decreasing volume acts
to increase the pressure of the matrix polymer mixture to obtain a
polymer melt (if solid starting material was used) and/or to
increase the pressure of the polymer melt.
[0061] As the matrix polymer mixture advances through the screw
extruder, a port configured for injecting one or more additives
into the polymer mixture may be provided through the barrel. In
some embodiments, additives such as processing aids, nucleating
agents, flame retardant agents, antioxidants, or stabilizers may
also be introduced to the polymer mixture through the port.
Similarly, one or more additional ports may be provided through the
barrel for injecting one or more blowing agent compositions into
the polymer mixture. In some embodiments, one or more optional
additives and blowing agent compositions are introduced through a
single port. In some embodiments, optional additives and blowing
agent compositions, are introduced through a plurality of ports.
Once these additives and blowing agent compositions have been
introduced into the matrix polymer mixture, the resulting mixture
is subjected to some additional blending sufficient to distribute
each of the additives generally uniformly throughout the polymer
mixture to obtain an extrusion composition.
[0062] This extrusion composition is then forced through an
extrusion die, and exits the die into a region of reduced pressure
(which may be below atmospheric pressure), thereby allowing the
blowing agent composition to expand and produce a polymer foam
material. This pressure reduction may be obtained gradually as the
extrusion composition advances through successively larger openings
provided in the die or through some suitable apparatus provided
downstream of the extrusion die for controlling to some degree the
manner in which the pressure applied to the extrusion composition
is reduced. The extruded and expanded polymer foam material may be
subjected to additional processing such as calendaring, water
immersion, cooling sprays, or other operations to control the
thickness and other properties of the resulting polymer foam
material.
[0063] In some embodiments, the polymer foams of the present
disclosure are extruded polymer beads made by a bead extrusion
method. Bead extrusion is similar to the extrusion process
previously described. However, in bead extrusion, the extrusion die
contains a plurality of small holes such that the extrusion
composition is extruded as beads. These beads are typically in the
range of about 0.05 mm to about 2.0 mm in diameter. Furthermore,
the extrusion composition is not allowed to foam once the beads
containing the extrusion composition exit the extrusion die.
Instead, the beads containing the extrusion composition are
discharged into a coolant chamber or coolant bath, and the beads
are rapidly cooled to below the glass transition temperature
(T.sub.g) of the extrusion composition. This rapid cooling prevents
the extrusion composition in the beads from foaming.
[0064] In some embodiments of bead extrusion, the matrix polymer,
blowing agent composition, and optional additives are introduced to
the extruder as described above to form an extrusion composition.
In some embodiment of bead extrusion, the matrix polymer and
optional additives are introduced to the extruder as described
above to form an extrusion composition, but the blowing agent
composition is added to the extruded beads via a pressure vessel
after the beads have been extruded and cooled.
[0065] In some embodiments, the polymer foams of the present
disclosure are expanded polymer foams made by an emulsion or
suspension polymerization method. In some embodiments of expanded
polymer foams, the matrix polymer is polymerized from monomer
dispersed in a liquid phase within a reaction vessel. In some
embodiments, a blowing agent composition is added to the polymer
mixture by adding the blowing agents as diluents within the liquid
phase within the reaction vessel during the polymerization
reaction. In some embodiments, a blowing agent composition is used
as the liquid phase within the reaction vessel during the
polymerization reactions. In some embodiments, the blowing agent
composition is added to the polymer mixture in a pressure vessel
after the polymerization reaction has been completed.
[0066] This extrusion composition is then forced through an
extrusion die and exits the die into a region of reduced pressure
(which may be below atmospheric pressure), thereby allowing the
blowing agent to expand and produce a polymer foam layer or slab.
The polymer foam may be subjected to additional processing such as
calendaring, water immersion, cooling sprays or other operations to
control the thickness and other properties of the resulting polymer
foam product.
Polymer Foam
[0067] The manufacturing process produces a polymer foam. In some
exemplary embodiments, the manufacturing process of the foamable
polymer mixture produces rigid, substantially closed cell, polymer
foam boards prepared by an extruding process. Extruded foams have a
cellular structure with cells defined by cell membranes and struts.
Struts are formed at the intersection of the cell membranes, with
the cell membranes covering interconnecting cellular windows
between the struts.
[0068] In some exemplary embodiments, the foams have an average
density of less than 5 pounds per cubic foot ("pcf"), or less than
4 pcf, or less than 3 pcf. In some exemplary embodiments, the
polymer foam has a density from about 1 pcf to about 4.5 pcf,
including from about 1.2 pcf to about 4 pcf, including from about
1.3 pcf to about 3.5 pcf, including from about 1.4 pcf to about 3
pcf, including from about 1.5 pcf to about 2.8 pcf, including from
about 1.6 pcf to about 2.6 pcf, including from about 1.7 pcf to
about 2.5 pcf, including from about 1.8 pcf to about 2.4 pcf,
including from about 1.9 pcf to about 2.3 pcf, including from about
2.0 pcf to about 2.2 pcf. In some exemplary embodiments, the
polymer foam has a density of about 2.0 pcf, or lower than 2.0
pcf.
[0069] It is to be appreciated that the phrase "substantially
closed cell" is meant to indicate that the foam contains all closed
cells or nearly all of the cells in the cellular structure are
closed. In some embodiments, not more than 20% of the cells are
open cells, and particularly, not more than 10%, or more than 5%
are open cells, or otherwise "non-closed" cells. In some
embodiments, from about 0.5% to about 4.0% of the cells are open
cells, including from about 0.75% to about 3.5%, including from
about 1.0% to about 3.2%, including from about 1.2% to about 3.0%,
including from about 1.5% to about 2.8%, including from about 1.75%
to about 2.5%, and including from about 2.0% to about 2.25% of the
cells are open cells. The closed cell structure helps to increase
the R-value of a formed, foamed insulation product. It is to be
appreciated, however, that it is within the purview of the present
invention to produce an open cell structure.
[0070] The average cell size of the matrix polymer cells in the
inventive foam and foamed products may be from about 0.05 mm (50
.mu.m) to about 0.4 mm (400 .mu.m), including from about 0.1 mm
(100 .mu.m) to about 0.3 mm (300 .mu.m), including from about 0.11
mm (110 .mu.m) to about 0.25 mm (250 .mu.m), including from about
0.12 mm (120 .mu.m) to about 0.2 mm (200 .mu.m), including from
about 0.13 mm (130 .mu.m) to about 0.18 mm (180 .mu.m), and
including from about 0.14 mm (140 .mu.m) to about 0.16 mm (160
.mu.m). The inventive foam may be formed into an insulation product
such as a rigid insulation board, insulation foam, packaging
product, and building insulation or underground insulation (for
example, highway, airport runway, railway, and underground utility
insulation).
[0071] The inventive foamable polymer mixture additionally may
produce polymer foams that have a high compressive strength, which
defines the capacity of a foam material to withstand axially
directed pushing forces. In some embodiments, the inventive foam
compositions have a compressive strength within the desired range
for polymer foams, which is from about 6 psi and 120 psi. In some
embodiments, the inventive foamable polymer mixture produces foam
having a compressive strength from about 10 psi and about 110 psi,
including from about 20 psi to about 100 psi, including from about
25 psi to about 90 psi, including from about 30 psi to about 80
psi, including from about 35 psi to about 70 psi, including from
about 40 psi to about 60 psi, including from about 45 psi to about
50 psi.
[0072] The inventive foamable polymer mixture additionally may
produce polymer foams that have a high level of dimensional
stability. For example, the change in dimension in any direction is
5% or less, such as 3% or less, 2% or less, and 1.5% or less. As
used herein, the average cell size is an average of the cell sizes
as determined in the X, Y, and Z directions. In particular, the "X"
direction is the direction of extrusion, the "Y" direction is the
cross machine direction, and the "Z" direction is the thickness. In
the present invention, the highest impact in cell enlargement is in
the X and Y directions, which is desirable from an orientation and
R-value perspective. In addition, further process modifications
would permit increasing the Z-orientation to improve mechanical
properties while still achieving an acceptable thermal property.
The inventive polymer foam can be used to make insulation products
such as rigid insulation boards, insulation foam, and packaging
products.
[0073] Additionally, the inventive foam composition produces
polymer foams that have insulation values (R-values) per inch of at
least 4, or from about 4 to about 7. R-value, or total thermal
resistance, is the measure of the resistance of heat transfer. The
method of determining R-value is described as follows. Thermal
conductivity, k, is defined as the the ratio of the heat flow per
unit cross-sectional to the temperature drop per unit thickness,
with the US unit:
k = Btu in hr ft 2 .degree. .times. F . ##EQU00001##
and the metric unit:
k = W m K ##EQU00002##
The heat transfer through an insulating material can occur through
solid conductivity, gas conductivity, radiation, and convection.
The total thermal resistance (R-value), R is the measure of the
resistance to heat transfer, and is determined as:
R=t/k
where t=thickness.
[0074] The thermal conductivity k, after the inventive foam has
aged 7 days, is from about 0.16 to about 0.18
Btuin/hrft.sup.2.degree. F., including from about 0.162 to about
0.178, including from about 0.164 to about 0.176, including from
about 0.166 to about 0.174, including from about 0.168 to about
0.172, including about 0.170 Btuin/hrft.sup.2.degree. F. The
thermal conductivity k, after the inventive foam has aged 60 days,
is from about 0.17 to about 0.185 Btuin/hrft.sup.2.degree. F.,
including from about 0.172 to about 0.184, including from about
0.174 to about 0.182, including from about 0.175 to about 0.181,
including from about 0.176 to about 0.180, including about 0.178
Btuin/hrft.sup.2.degree. F.
EXAMPLES
Example 1
[0075] A series of experiments were conducted to form 1.0 inch
extruded polystyrene (XPS) foam samples using various hydrocarbons
as co-blowing agents with HFO-1234ze. The hydrocarbon co-blowing
agents tested included n-butane, isobutane, n-pentane, isopentane,
and cyclopentane. For each foam sample, the formulation comprised
98.5 wt. % polystyrene, 1 wt. % flame retardant, 0.5 wt. % infrared
attenuation agent, and 7.8 wt. % blowing agent composition. The
amount of each blowing agent component is given in wt. % of the
total composition, and in number of moles per 100 g of matrix
polymer. The blowing agent composition formulations and physical
properties of each test sample are given in Tables 1-5 below.
TABLE-US-00001 TABLE 1 Foam formulations with n-butane and
HFO-1234ze HFO- n- Total 7-days HFO- 1234ze n- butane Total BA Foam
k-factor Sample 1234ze (moles/ butane (moles/ BA (moles/ Density
(Btu in/ No. (%) 100 g) (%) 100 g) (%) 100 g) (lb/ft.sup.3) h
ft.sup.2 .degree. F.) A-1 7.55 0.0662 0.25 0.0043 7.80 0.0705 2.31
0.1685 A-2 7.33 0.0640 0.50 0.0086 7.80 0.0726 2.31 0.1685 A-3 7.05
0.0618 0.75 0.0129 7.80 0.0747 2.31 0.1679 A-4 6.80 0.0596 1.00
0.0172 7.80 0.0811 2.32 0.1681 A-5 6.30 0.0553 1.50 0.0258 7.80
0.0853 2.24 0.1687 A-6 5.80 0.0509 2.00 0.0344 7.80 0.0853 2.19
0.1730
TABLE-US-00002 TABLE 2 Foam formulations with isobutane and
HFO-1234ze HFO- Iso- Total 7-days HFO- 1234ze Iso- butane Total BA
Foam k-factor Sample 1234ze (moles/ butane (moles/ BA (moles/
Density (Btu in/ No. (%) 100 g) (%) 100 g) (%) 100 g) (lb/ft.sup.3)
h ft.sup.2 .degree. F.) B-1 7.55 0.0662 0.25 0.0043 7.80 0.0705
2.24 0.1709 B-2 7.33 0.0640 0.50 0.0086 7.80 0.0726 2.24 0.1698 B-3
7.05 0.0618 0.75 0.0129 7.80 0.0747 2.26 0.1696 B-4 6.80 0.0596
1.00 0.0172 7.80 0.0811 2.25 0.1689 B-5 6.30 0.0553 1.50 0.0258
7.80 0.0853 2.21 0.1694 B-6 5.80 0.0509 2.00 0.0344 7.80 0.0853
2.28 0.1712
TABLE-US-00003 TABLE 3 Foam formulations with n-pentane and
HFO-1234ze HFO- n- Total 7-days HFO- 1234ze n- pentane Total BA
Foam k-factor Sample 1234ze (moles/ pentane (moles/ BA (moles/
Density (Btu in/ No. (%) 100 g) (%) 100 g) (%) 100 g) (lb/ft.sup.3)
h ft.sup.2 .degree. F.) C-1 7.55 0.0662 0.25 0.0035 7.80 0.0697
2.28 0.1656 C-2 7.33 0.0640 0.50 0.0069 7.80 0.0710 2.22 0.1670 C-3
7.05 0.0618 0.75 0.0104 7.80 0.0722 2.23 0.1672 C-4 6.80 0.0596
1.00 0.0139 7.80 0.0735 2.26 0.1667 C-5 6.30 0.0553 1.50 0.0208
7.80 0.0761 2.23 0.1679 C-6 5.80 0.0509 2.00 0.0277 7.80 0.0786
2.22 0.1685
TABLE-US-00004 TABLE 4 Foam formulations with isopentane and
HFO-1234ze HFO- Iso- Total 7-days HFO- 1234ze Iso- pentane Total BA
Foam k-factor Sample 1234ze (moles/ pentane (moles/ BA (moles/
Density (Btu in/ No. (%) 100 g) (%) 100 g) (%) 100 g) (lb/ft.sup.3)
h ft.sup.2 .degree. F.) D-1 7.55 0.0662 0.25 0.0043 7.80 0.0705
2.33 0.1677 D-2 7.33 0.0640 0.50 0.0086 7.80 0.0726 2.25 0.1710 D-3
7.05 0.0618 0.75 0.0129 7.80 0.0747 2.25 0.1698 D-4 6.80 0.0596
1.00 0.0172 7.80 0.0811 2.26 0.1695 D-5 6.30 0.0553 1.50 0.0258
7.80 0.0853 2.21 0.1673 D-6 5.80 0.0509 2.00 0.0344 7.80 0.0853
2.21 0.1669
TABLE-US-00005 TABLE 5 Foam formulations with cyclopentane and
HFO-1234ze HFO- Cyclo- Total 7-days HFO- 1234ze Cyclo- pentane
Total BA Foam k-factor Sample 1234ze (moles/ pentane (moles/ BA
(moles/ Density (Btu in/ No. (%) 100 g) (%) 100 g) (%) 100 g)
(lb/ft.sup.3) h ft.sup.2 .degree. F.) E-1 7.55 0.0662 0.25 0.0036
7.80 0.0698 2.28 0.1669 E-2 7.33 0.0640 0.50 0.0071 7.80 0.0712
2.24 0.1670 E-3 7.05 0.0618 0.75 0.0107 7.80 0.0725 2.19 0.1674 E-4
6.80 0.0596 1.00 0.0143 7.80 0.0739 2.17 0.1673 E-5 6.30 0.0553
1.50 0.0214 7.80 0.0767 2.21 0.1665 E-6 5.80 0.0509 2.00 0.0285
7.80 0.0794 2.22 0.1665
[0076] A graph of the thermal insulation (7-days k-factor) for each
foam formulation is shown in FIG. 1. For each formulation, the
thermal insulation properties remain relatively constant as the
amount of HFO is varied. There does not appear to be an immediate
advantage to increasing the weight percent of HFO blowing agent (an
expensive ingredient) relative to the hydrocarbon co-blowing agent
in freshly-manufactured polymer foams.
Example 2
[0077] The foam formulations of Example 1 were analyzed for thermal
insulation properties as the samples aged. The thermal aging curves
for C1-C6 (the foam formulations comprising n-pentane as the
co-blowing agent) are shown in FIG. 2. Thermal aging curves for the
other foam formulations of Example 1 follow the same general trends
as shown in FIG. 2.
[0078] As the HFO/n-pentane foams age, the foam sample with the
highest concentration of HFO (sample C-1) has slightly better
thermal insulating properties than the foam samples with lower
concentrations of HFO (samples C-2 to C-6). However, it should be
noted that sample C-1 has about 30% more HFO than does sample C-6
(7.55 wt. % versus 5.80 wt. %), but the k-factor for C-1 at 60 days
is only about 2% better than C-6 (0.181 versus 0.185). There does
not appear to be a large long-term advantage as the polymer foam
ages to increasing the weight percent of HFO blowing agent (an
expensive ingredient) relative to the hydrocarbon co-blowing
agent.
Example 3
[0079] The foam formulations from Example 1 comprising 5.8 wt. %
HFO and 2.0 wt. % hydrocarbon (i.e., samples A-6, B-6, C-6, D-6,
and E-6) were compared for thermal insulating properties as they
aged. As a comparative example, a similar foam comprising 5.80 wt.
% HFO-1234ze and 2.00 wt. % HFC-152 was also evaluated for its
thermal insulating properties as it aged. The thermal aging curves
for these samples are shown in FIG. 3.
[0080] The foam sample comprising HFO and isobutane (sample B-6)
has the best thermal insulating properties, with a k-factor of
about 0.180 Btuin/hft.sup.2.degree. F. after 60 days. The foam
sample comprising HFO and isopentane (sample D-6) has the next best
thermal insulating properties, with a k-factor of about 0.183
Btuin/hft.sup.2.degree. F. after 60 days. The foam samples with
n-butane, n-pentane, and cyclopentane (samples A-6, C-6, and E-6,
respectively) have comparable thermal insulating properties, with
k-factors of about 0.184-0.185 Btuin/hft.sup.2.degree. F. after 60
days. The comparative sample (sample COMP), with HFO and HFC, has
the poorest thermal insulating properties, with a k-factor of about
0.188 Btuin/hft.sup.2.degree. F. after 60 days. These results
suggest that polymer foams using blowing agents comprising HFO and
a branched hydrocarbon, such as isobutane or isopentane, have
superior thermal insulating properties over similar foams using
blowing agents comprising HFO and linear or cyclic hydrocarbons,
such as n-butane, n-pentane, or cyclopentane. Additionally, polymer
foams using blowing agents comprising HFO and a branched
hydrocarbon, such as isobutane or isopentane, also have superior
thermal insulating properties over similar foams using blowing
agents comprising HFO and HFC, and excluding branched
hydrocarbons.
Example 4
[0081] The data presented in FIG. 3 for Example 3 was normalized to
compare the hydrocarbon co-blowing agents on a molar (2.88
moles/100 g matrix polymer) rather than weight (2.0 wt. %) basis in
each composition. The normalized thermal aging curves are shown in
FIG. 4. When normalized in this way, the foams with isopentane,
isobutane, and n-butane (samples D-6, B-6, and A-6, respectively)
have superior thermal insulating properties compared to the foams
with n-pentane and cyclopentane (samples C-6 and E-6,
respectively). The comparative sample (sample COMP), still has the
poorest thermal insulating properties.
Example 5
[0082] A series of experiments were conducted to form extruded
polystyrene (XPS) foam samples at the lowest possible densities,
using HFO-1234ze blowing agent at 3.00 wt. % and various
hydrocarbon co-blowing agents at 4.80 wt. %. The hydrocarbon
co-blowing agents tested included n-butane, isobutane, n-pentane,
isopentane, and cyclopentane. The thickness of the samples was held
constant at 1.00 inch. For a 1.0 inch board the R-value is 5 or
thermal conductivity is 0.20 Btuin/ft.sup.2h.degree. F. The R-value
is the inverse of the thermal conductivity. The lower the thermal
conductivity the higher the R-value. As a comparative example, a
similar foam comprising 3.00 wt. % HFO-1234ze and 4.80 wt. %
HFC-152a was also evaluated for its thermal insulating properties
as it aged. For each foam sample, the formulation comprised 98.5
wt. % polystyrene, 1 wt. % flame retardant, 0.5 wt. % infrared
attenuation agent, and 7.8 wt. % blowing agent composition. The
blowing agent composition formulations for each series of test
samples are given in Tables 6 below.
TABLE-US-00006 TABLE 6 Foam formulations with 3.00 wt. % HFO-1234ze
and 4.80 wt. % co-blowing agent HFO- n- Iso- n- Iso- Cyclo- HFC-
HFO- 1234ze n- butane Iso- butane n- pentane Iso- pentane Cyclo-
pentane HFC- 152a Sample 1234ze (moles/ butane (moles/ butane
(moles/ pentane (moles/ pentane (moles/ pentane (moles/ 152a
(moles/ No. (%) 100 g) (%) 100 g) (%) 100 g) (%) 100 g) (%) 100 g)
(%) 100 g) (%) 100 g) F-1 3.00 0.0263 4.80 0.0826 -- -- -- -- -- --
-- -- -- -- F-2 3.00 0.0263 -- -- 4.80 0.0826 -- -- -- -- -- -- --
-- F-3 3.00 0.0263 -- -- -- -- 4.80 0.0665 -- -- -- -- -- -- F-4
3.00 0.0263 -- -- -- -- -- -- 4.80 0.0665 -- -- -- -- F-5 3.00
0.0263 -- -- -- -- -- -- -- -- 4.80 0.0684 -- -- F-6 3.00 0.0263 --
-- -- -- -- -- -- -- -- -- 4.80 0.0727
[0083] FIG. 5 shows a graph of the thermal aging curves for foams
at various densities using a blowing agent of 3.00 wt. % HFO and
4.80 wt. % isobutane. The foams each included less than 0.03 moles
of HFO-1234ze. The foam sample with a density of 2.52 lb/ft.sup.3
has the highest thermal resistance, with a k-factor of about 0.179
Btuin/hft.sup.2.degree. F. after 180 days. However, the foams with
lower densities also had acceptable thermal resistance values, with
180-day k-factors ranging from about 0.180 to about 0.194
Btuin/hft.sup.2.degree. F. for foams with densities from 2.25 to
1.43 lb/ft.sup.3, respectively. As mentioned above, an R-value of 5
for a 1.0 inch board has a thermal conductivity of 0.20
Btuin/ft.sup.2h.degree. F. Thus, each foam sample achieved an
R-value of at least 5.
[0084] FIG. 6 shows a graph comparing foams containing the
different hydrocarbon co-blowing agents at various densities. For
all foam densities, Samples F-2 and F-4, which contain the
co-blowing agents isobutane and isopentane, respectively, have
better thermal resistance (lower k-factors) after 7 days than do
Samples F-1 and F-3, which contain n-butane and n-pentane,
respectively. The dotted line at 1.75 lb/ft.sup.3 density
designates the target density for most commercial foams. FIG. 6
shows that foam products with densities substantially lower than
1.75 lb/ft.sup.3 can have acceptable thermal resistance when
isobutane or isopentane are used as co-blowing agents and an HFO as
a blowing agent.
Example 6
[0085] A series of experiments were conducted to form extruded
polystyrene (XPS) foam samples using various concentrations of
HFO-1234ze, isobutane, and carbon dioxide. The target foam density
was 2.25+/-0.05 lb/ft.sup.3. The CO.sub.2 was used to maintain the
total blowing agent at 7.8 wt. % of the foamable material, while
the concentrations of HFO-1234ze and isobutane was varied. The
ratio between the HFO and isobutane was kept constant at 1.6. For
each foam sample, the formulation comprised 98.5 wt. % polystyrene,
1 wt. % flame retardant, 0.5 wt. % infrared attenuation agent, and
7.8 wt. % blowing agent composition. The amount of each blowing
agent component is given in wt. % of the total composition, and in
number of moles per 100 g of matrix polymer. The blowing agent
composition formulations, foam density, 7-day k-factor of each
sample is provided below in Table 7.
TABLE-US-00007 TABLE 7 Foam formulations containing various
concentrations of HFO-1234ze, isobutane and carbon dioxide. 7-days
HFO- HFO- k-factor Sample 1234ze 1234ze isobutane isobutane
CO.sub.2 CO.sub.2 Density (Btu in/ No (%) (moles) (%) (moles) (%)
(moles) (lb/ft.sup.3) h ft.sup.2 .degree. F.) G-1 3.00 0.0263 4.80
0.0826 0.000 0.0000 2.25 0.1685 G-2 2.90 0.0254 4.65 0.0800 0.125
0.0028 2.25 0.1694 G-3 2.81 0.0246 4.49 0.0773 0.250 0.0057 2.25
0.1695 G-4 2.71 0.0238 4.34 0.0747 0.375 0.0085 2.31 0.1699 G-5
2.62 0.0230 4.18 0.0719 0.500 0.0114 2.30 0.1705 G-6 2.52 0.0221
4.03 0.0693 0.625 0.0142 2.26 0.1708 G-7 2.42 0.0212 3.88 0.0668
0.750 0.0170 2.24 0.1713 G-8 2.33 0.0204 3.72 0.0640 0.850 0.0193
2.26 0.1739 G-9 2.23 0.0196 3.57 0.0614 1.000 0.0227 2.30 0.1767
G-10 1.85 0.0162 2.95 0.0508 1.500 0.0341 2.30 0.1801
[0086] The foams thermal aging curves with various concentrations
of HFO-1234ze, isobutane and carbon dioxide are shown in FIG. 7.
The curves show that the thermal conductivity of the foam increases
as the concentration of the HFO-1234ze and isobutane is decreased
and replaced with carbon dioxide.
[0087] Although the invention has been described in the context of
particular polystyrene foam materials, the inventive method is also
applicable to other polymer compositions and various combinations
of blending agents to obtain a variety of polymer foam materials.
Example embodiments of the invention have been disclosed herein
and, although specific terms are employed, they are used and are to
be interpreted in a generic and descriptive sense only and not for
purpose of limitation. Accordingly, it will be understood by those
of ordinary skill in the art that various changes in form and
details of the disclosed apparatus and methods may be made without
departing from the spirit and scope of the invention as set forth
in the following claims.
* * * * *