Note: Descriptions are shown in the official language in which they were submitted.
~ ~3~3
PROCESS FOR THE PREPARATION OF
LOW K-FACTOR CLOSED CELL
PHENOL-ALDEHYDE FOAM
The present invention relates to phenolic
foams prepared from resole resins. More particularly,
the present invention relates to generally closed cell
phenolic foams which are prepared from resole resins
and which have a K-factor of less than 0.032 in SI
units (0.22 in English units).
Phenol-aldehyde foams have been prepared for
many years by a method which involves the addition of
an acid catalyst to a liquid phenol-aldehyde resole
resin. Polymerization of the resole resin commences
very quickly following the addition of the acid catalyst.
Since the reaction is highly exothermic, the heat
liberated by the reaction rapidly increases the tem-
perature of the reaction mixture. The continuing
increase in reaction temperature progressively in-
creases the rate of polymerization. Accordingly,
the reaction proceeds to completion very quickly.
In fact, once initiated, the reaction is generally
considered to be nearly impossible to control. The
temperature of the reaction mixture increases suf-
27,927A-F
1~9393
--2--
ficiently to cause the formation of enough steam from
the water originally present in the resole resin and
the water formed during reaction to foam the resin.
The accompanying high reaction temperature causes the
initially liquid resole resin to cure to a solid infus-
ible state before the foam collapses. The phenol-aldehyde
foam thus prepared usually has an open cell structure.
The open cell structure does not provide for optimum
properties with regard to thermal conductivity and
resistance to moisture absorption. In addition, it has
been found that open cell phenol-aldehyde foam has a
tendency to punk, that is, to continue to glow red hot
and to smolder after high heat is applied and then
removed. However, in general the open cell foam has
excellent fire resistance and generates only a small
- amount of smoke when subjected to high temperatures.
In addition to the foregoing difficulties, it
has been found that most known cellular materials produced
from phenolic polymers exhibit an unsatisfactory thermal
conductivity initially. Other known cellular materials
produced from phenolic polymers exhibit an undesirable
increase in thermal conductivity with time.
Accordingly, it is an object of the present
invention to provide a process for preparing a closed
cell phenol-aldehyde foam material substantially free
of the disad~antages of prior foams.
Another object is to provide a process for
preparing closed cell phenol-aldehyde resin foa~ material
which exhibits a high closed cell content without
27,927A-F -2-
~24~393
--3--
adversely affecting friability, compressive strength
and the low flammability characteristics of the
material.
The present invention is an improved process
for preparing a generally closed cell, low K-factor
foam material, the foam material resulting from a
process wherein a phenol-aldehyde resole resin, a
blowing agent and a surfactant are admixed with an
acid catalyst to form an admixture which is then
poured into a forming means and cured, wherein the
improvement comprises:
(a) stripping the resole resin, in the
presence of a viscosity-modifying amount of a suit-
able solvent, to a water content of less than 7
weight percent, based on resin weight, and to a work-
able viscosity; and
(b) adding from 10 to 20 weight percent,
based on resin weight, of an unbranched dihydroxy
ether polyglycol having a molecular weight greater
than 300 to the stripped resole resin.
Any thermosetting phenol-aldehyde resin in
a water-insoluble liquid state may be employed in com-
positions of the present invention. In general,
such resins are prepared by condensation of one mol-
ecular equivalent of a monohydric phenol which isunsubstitu-ted in at least one of the two-, four-
and six-positions of the benzene nucleus, with
between 1 and 2.5, preferably between 1.4 and 1.5,
molecular equivalents of an aldehyde and discon-
tinuing the condensation reaction when the pro-
duct becomes water-insoluble, but remains liquid.
Procedures for making such liquid phenol-aldehyde
27,927A-F -3-
~Z49393
--4--
condensation products are well known in the art and
need not be given in de-tail. However, the condensation
reaction is generally started under alkaline conditions,
e.g., using from 1 to 2 percent by weight of sodium
hydroxide, potassium hydroxide, sodium carbonate, or
other basic catalysts, and carried out at temperatures
of from about 40 -to about~70 Centigrade (C). The
condensation reaction is carried out to a point at
which the product is a fairly thin, water-soluble
liquid. The liquid is then acidified by adding a
strong aqueous mineral acid such as hydrochloric or
sulfuric acid. The reaction is then continued at
temperatures of ~rom about 40 to about 70C until the
mixture becomes fairly viscous and is water-insoluble.
The reaction is then preferably stopped short of the
solidification point. It is essential that the phenol-
aldehyde condensation reaction be carried to a point at
which the product thereof is substantially water-insoluble,
although said product itself may have from 20 to 35
percent of water dissolved in it. After carrying the
phenol-aldehyde condensation reaction out in the presence
of an acid to a point at which the product is a water-
insoluble liquid, the mixture is neutralized, e.g.,
with aqueous ammonia, sodium hydroxide, potassium
hydroxide, sodium carbonate, or potassium carbonate,
and washed thoroughly with water. The condensation
product usually retains 20 to 35 percent by weight of
dissolved water. In most ins~ances,-such condensation
product of phenol and aldehyde has a viscosity of about
0.3 to 0.4 pascal seconds ("Pa-s" or in English units,
about 300 to 400 centipoise) at 25C, but it may be
lower or higher in viscosity.
27,927A-F -4-
3L249393
--5--
Upon standing, an aqueous layer separates
from the resin and is decanted off. The resin layer
is then washed with an equal volume of water. After
wash water is decanted, the resin is vacuum stripped
of additional water until the desired water content
and/or viscosity is reached. A viscosity adjusting
amount of a solvent is added before vacuum stripping.
Typical of the phenols that are useful in
producing suitable resole resins suitable for the
purposes of the present invention are those repre-
sented by the formula:
OH
R~ ~ R' I
wherein at least two groups represented by R' are
hydrogen atoms and the groups represented by R and
any remaining group represented by R' are hydrogen
atoms or groups which do not impede the condensation
of the phenol with an aldehyde. Examples of suitable
groups are a substituent such as halogen atom or a
hydroxy, alkyl or aryl group. Illustrative of
suitable phenols are phenol, cresols (particularly
M-cresol), xylenols (particùlarly 3,5-xylenol),
and dihydroxybenzenes (particularly resorcinol).
Typical of the aldehydes that can be used
in producing suitable resole resins for purposes of
the present invention are formaldehyde (including
27,927A-F -5-
39~
the oligomers and polymers of formaldehyde such as
trio~ane), furfural, sugars and cellulose hydroly-
zates. Such aldehydes can be employed without
dilution or dissolved in suitable solven-ts including
aqueous alcohols (e.g., aqueous methanol, N-propanol,
isobutanol or N-butanol).
The solvent employed to adjust the vis-
cosity of the resole resin is suitably selected
from the group consisting of phenol, aniline,
resorcinol, cresol and aminophenol. Desirably the
solvent is selected from the group consisting of
phenol and aniline. The solvent is suitably present
in an amount sufficient to adjust the viscosity
of the resole resin in such a manner that after
vacuum stripping, the viscosity of the resole resin
will be less than 3.5 Pa s (3,500 centipoise).
The resole resin is stripped via vacuum
stripping to a water level, or content, of less than
7 percent by weight based on weight of the resin.
Desirably, the resole resin is stripped to a water
content of from 3 to 6 percent by weight based on
weight of resin.
The amount of solvent which is added to the
resole resin to adjust the viscosity is suitably
from 8 to 20 weight percent based on weight of the
resin. It is believed that at least a portion of
the solvent is capable of reacting with the resole
resin during crosslinking reactions which take place
during foaming.
Th~ polyglycols which are believed to function
27,927A-F -6-
12~9393
--7--
as heat sinks for purposes of the present inventlon
are suitably selected from the group consisting
of unbranched dyhydroxy ether polyglycols ha~ing a
molecular weigh-t greater than 300. The polyglycol
is preferably polyethylene glycol or polypropylene
glycol.
-
The acids employed as catalysts are the
~ strong inorganic acids such as sulphuric acidhydrochloric acid, phosphoric acid, nitric acidi
i.e., the strong mineral acids or aqueous
solutions of such acids, e.g., a concentrated
aqueous solution of hydrochloric acid, or strong
organic acids such as benzene sulfonic acid, a
toluene sulfonic acid, phenol sulfonic acid,
xylene sulfonic acid, beta-naphthalene sulfonic
acid and alpha-naphthalene sulfonic acid. Mix-
tures of any two or more of the acids can also
be used. Desirably, the acid employed as a catalyst
is benzene sulfonic acid monohydrate.
Oftentimes in order to stabilize pre-
gelled foam, a surfactant or surface active agent
i9 employed. Beneficially the surfactant is a
nonionic surfactant such as the reaction or con-
densation product of an alkylene oxide having from
two to four carbon atoms in the molecule with a
compound such as higher alkyl phenols having from
8 to 12 carbon atoms in the alkyl group, f~atty
acids having from 12 to 20 carbon atoms and alkyl
siloxanes. Among suitable surfactants are (a)
the polyoxyethylene ethers of alkyl phenols having
the general formula:
27,927A-F -7-
~4C~393
~ -O-(C2H4O)m-H II
R
wherein R is an alkyl group having from 8 to 12
carbon atoms and m is an integer of from about 8
to 20; (b) ethoxylated castor oil and ethoxylated
hydrogenated castor oil; i.e., the condensation
product of said castor oils and from 8 to 24 mols
of ethylene oxide per mol of said castor oil; (c)
copolymers of ethylene oxide and/or propylene oxide
containing from 8 to 20 moieties of each of said
alkylene oxides, and alkyl siloxane polyoxyalkylene
block copolymers similar to those described in U.S.
Patent No. 2,834,748. In addition, fluorinated
surfactants having an alkyl fluorocarbon hydro-
phobic portion are also suitable.
Beneficially, the surfactant is an alkylsiloxane alkylene oxide block copolymer of the
- formula:
~CH
C2H5-Si- [ - ~Si-O - _ (CnH2nO)30-C4Hl0]3 III
CH3
wherein CnH2nO is a mixed oxyethylene/oxypropylene
block of about 17 oxyethylene units and abaut 13
oxypropylene units; or an alkyl siloxane alkylene
oxide copolymer of the formula: -
27,927A-F -8-
~%~9393
g
CH3 ,CH3
(CH3)3SiOtSiO)X - (siO ~ SitCH3)3 IV
CH3 CH2
CH2
H~CH2CH2 ) Z H2
wherein x is an integer equal to 15 or 16, y is an
integer equal -to 2 or 3 and z is an integer equal to 10
or 11; or an ethoxylated castor oil, i.e., the con-
densation product of castor oil and about 23 mols of
ethylene oxide per mol of said castor oil.
Any blowing agent characteristically employed
in similar prior art products can be employed in the
process and the product of the process of the present
invention. In general, these blowing agents are liquids
having an atmospheric pressure boiling point between
-50 and 100C and preferably between 0 and 50C. The
preferred liquids are hydrocarbons or-halohydrocarbons.
Examples of suitable blowing agents include, among
others, chlorinated and fluorinated hydrocarbons such
as trichlorofluoroethane, trichlorofluoromethane,
CC12FClCF2, CC12FCF3, diethyl ether, isopropyl ether,
N-pentane, cyclopentane, and 2-methylbutane. The
blowing agent is desirably trichlorotrifluoroethane.
It is known in the art that K-factor changes
as a function of time and that diffusion of fluoro-
carbon gases out of unfaced foam and fusion of airinto the foam causes an increase in K-factor.
27,927A-F -9-
c~3g3
--10--
A slow K-drift foam is defined as one that
attains a K-factor at 24C of 0.022 to 0.024 after 200
to 400 days and then reamins below a K-factor of 0.029
for 5 to 10 years. Eventually all fluorocarbon diffuses
from the foam to leave a closed cell ma-terial which
contains only air in the cells.
The K-factor for the closed cell foam con-
taining only air falls in the range of 0.032 to 0.037
watts per meter kelvin (watt/m-K) at 24~C for foam in
32 to 48 kilogram per cubic meter (kg/m3) density
range. This is equivalent to 0.22 to 0.26 sritish
Thermal Units per hour - Fahrenheit - square foot
(hereinafter Btu/hr - F -ft2) per inch thickness at
24C for the 2 to 3 pounds per cubic foot density
range. Therefore, if a foam exhibits a K-factor of
greater than about 0.032 watt/(m-K) at 24C for the 32
to 48 kg/m3 density range after a short period of time
(less than 25 days), then substantially all fluoro-
carbon has diffused from the foam and has been replaced
by air. On the other hand, if the K-factor remains
below 0.032 watt/(m-K) at 24C for the 32 to 48 kg/m3
density range for at least 100 days, then a substantial
amount of fluorocarbon gas remains in the closed cells
of the foam in spite of infusion of air.
The closed cell foams produced in accordance
with the present invention beneficialLy have a K-factor
of less than 0.029 watt/(m-K) at 24C for the 32 to 48
kg/m3 density range. Desirably the K-factor for foams
produced in accordance with the present invention is
30 from 0.017 to 0.024 watt/(m-K) at 24C for the 32 to 48
kg/m3 density range.
27,927A-F -10-
~4~3~
It is know that typical resole resins contain
from about 10 to about 15 percent water based on resin
weight prior to foaming. It is also known that addi-
tional water is produced in the crosslinking reaction.
That wa-ter which is not converted to steam by heat of
the reaction is believed to separate as a microdroplet
phase upon acidification and curing. It has been found
that holes form throughout the structure when the
microdroplets evaporate. In addition, it is believed
that the steam that is generated by heat of the reac-
tion tends to cause large cells to be blown. The
combination of large cell size and hole formation is
believed to lead to a porous foam structure formed
largely of open and interconnecting cells which allow
easy diffusion from the structure of blowing agent.
Accordingly, the present invention is centered upon
making a closed cell resin.
When phenolic resole resins in general and
resins of the present invention in particular are
stripped of water to a water content of less than 10
weight percent based on resin weight, viscosity of the
resin increases dramatically. As water content of the
resin is further reduced to levels of less than 7
weight percent based on resin weight, viscosity
increases become even more pronounced. Typical resins
prior to stripping have a viscosity on the order of
about 0.2 Pa s to about 0.4 Pa-s. At ambient con-
ditions a resin which has been stripped to a water
content of less than 7 weight percent based on resin
weight has a viscosity on the order of 100 Pa s or
greater. A resin having a viscosity on the order of
about 100 Pa s presents a number of handling dif-
27,927A F -11-
~24~3~33
-12-
ficulties. In order to achieve a resin having both a
low viscosity (on the order of 3 Pa-s) and a low water
content (3 to 7 weight percent based on resin weight),
a viscosity adjusting amount of a solvent is added to
the resin prior to stripping.
In addition to increasing resin viscoslty,
stripping of water has been found to cause another
significant problem. The problem centers around increas-
ing temperatures in the foam during crosslinking. It
is believed that the water acts as a heat sink during
foaming to prevent explosive foaming such as is com-
monly seen in foaming of generally dry resole resins.
In accordance wlth the present invention, a polyglycol
is added. It is believed that the polyglycol acts as a
heat sink in that it acts to prevent excessive heat
build-up during the crosslinking reaction.
A typical phenolic resole-type resin contains
from about 10 to about 15 weight percent water based on
resin weight. In accordance with the present invention,
a viscosity adjusting amount of a solvent is added to
the resin prior to a vacuum stripping procedure to
reduce the water content to a level of from 3 to 7
weight percent based on resin weight. The solvents
suitable for purposes of the present invention have
hereinbefore been set forth. The viscosity adjusting
amount of solvent is desirably from 1.0 to 20 weight
percent based on weight of resin when the solvent is
added to the resin prior to stripping. The typical
phenolic resoletype resin also cortains from about 3 to
about 10 ~eight percent free phenol (where free phenol
is reacted to form the resole resin). Accordingly,
when free phenol is also used as a solvent, the total
27,927A-F -12-
amount of free phenol present is from about 13 to abou-t
30 weight percent based on weight of resin. Persons
skilled in the art will recognize that in stripping
water from the resin, an amount of solvent will also
be stripped from the resin solvent mixture. Such
persons will also recognize that it is generally true
that when larger amounts of water must be st~ipped, it
follows that larger amounts of solvent will also be
~ removed. After stripping has been completed, phenolic
resins of the present invention beneficially have a total
amount of a phenol, such as free phenol, plus a solvent,
as hereinbefore set forth, in the range of from about
10 to about 20 weight percent based on resin weight.
After the solvent addition and stripping
steps have been completed, the polyglycol, the sur-
factant, and the blowing agent are placed in admixture
with the stripped phenolic resins to form a reaction
mixture. Foaming commences following addition of the
acidic catalyst to the reaction mixture. The times,
temperatures and other reaction conditions are well
known in the art and usable in the practice of this
invention. Merely for the purpose of illustration and
not for limitation, reference is made to Organic
Chemistry of Synthetic High Polymers by Robert W. Lenz,
published in 1968 by Interscience Publishers, Inc., New
York, Chapter 4, "Carbonyl Addition-Substitution Reac-
tions," pps. 113-138 and 140-142 and to Polvmer
Processes, edited by Calvin E. Schildknecht, published
in 1956 by Interscience Publishers, Inc., New York,
Chapter 8, "Condensations With Formaldehyde", by
T. J. Suen.
The average cell size diameter is suitably
from about 0.1 to about 5 mm as measured in accordance
27,927A-F -13-
~L2~93~3
with American Society for Testing Materials (herein-
after ASTM) D-2842. Fine celled foams having a cell
.structure wherein generally all of the cells are closed
cells, can be prepared in accordance with the present
invention. The blowing agent is trapped in the cells.
One means of expressing the containment in the cells of
the blowing agent is by use of the K-factor drift
value. Unfaced cellular material containing fluoro-
carbon gas have initial K-factors in the vicinity of
0.014 to 0.029 watts/(m-K~ at 24C. This low value
increases over a period of months or sometimes days.
The change is expressed as the K-factor drift. The
K-factor is measured at a mean temperature of 24c.
The value is redetermined at various time intervals of
up to 1,000 days. A material exhibiting fast K-factor
drift will attain a K-factor of at least 0.029 watts/(m-K)
with 25 days. A slow K-factor drift materiai may
require between 200 days and over two years to attain a
K-factor of 0.029 watts/(m-K). Any material which
possesses a K-factor value under 0.029 watts/(m-K) will
provide high thermal resistance. Obviously, the longer
this value or a lower value is maintained, the better
- the efficiency of the insulation.
Foam Burn-Through Times are suitably deter-
mined by using the Burn Through Test detailed herein
under Testing Methods. Phenol-aldehyde foams prepared
in accordance with the present invent-ion suitably have
a Burn-Through Time of greater than 10 minutes, bene-
ficially greater than 20 minutes and desirably greater
than 30 minutes. In 'esting foam samples according to
the Burn Through Test, it has been observed that foam
samples having good Burn-Through Times (30 minutes or
more) consistently have a raised and charred section
27,927A-F -14-
~2~a9~393
where the flame touches the sample. By way of con-
trast, it has been observed that foam samples having
poor Burn-Through Times (lO minutes or less) lacked
the raised and charred section. In addition, the
samples having poor Burn-Through Time appear to
crack and pull away from the flame source thereby
allowing flame penetration.
It has been found that by varying amounts of
polyglycol and total phenol in a foamable mixture, both
based on weight of the phenol-aldehyde resin, one is
able to affect the Burn-Through Time of the foam pro-
duced therefrom. It is to be understood that the
expression "total phenol" refers to the total amount of
phenol plus solvent in the foamable mixture after
stripping of the phenol-aldehyde resin. A level of
polyglycol of greater than 15 percent by weight in
conjunction.with a total phenol level of greater than
14 percent by weight, both based on weight of the
phenol-aldehyde resin, will produce foams in accordance
with the present invention having satisfactory Burn-Through
Times. It has been found that at a 20 weight percent
level of polyglycol, a total phenol level of 13.9
weight percent will produce mixed results. That is, a
foamable mixture with such levels may yield either
satisfactory Burn-Through Times or unsatisfactory
Burn-Through Times (less than 10 minutes).
Autoxidation tendencies of foam samples are
suitably determined by using the Autoxidation Test
detailed herein under Testing Methods. Phenol-aldehyde
foams prepared in accordance with the present invention
generally exhibit no tendency to show an exotherm above
250C during the autoxidation test. Foams prepared
27,927A-F -15-
~Z~9393
generally in accordance with the presen-t invention but
containing less than 10 percent by weight, based on
weight of phenol-aldehyde resin, of a polyglycol sel-
ected from those hereinabove set forth tend to autoxi-
dize or exhibit an exotherm which rises quickly above
250C during the autoxidation test. Foams prepared in
accordance with the present invention with a polyglycol
level fixed at 20 weight percent based on weight of
resin but varying levels of total phènol exhibit no
tendency to autoxidize during the autoxidation test.
Accordingly, in order to inhibit autoxidation of phenol-
aldehyde foams prepared in accordance with the present
invention, it is necessary that a level of polyglycol
of at least 10 percent by weight based on weight of
resin must be included in a foamable reaction mixture.
The ~resent invention is further illustrated
by the following experiments in which all parts and
percentages are by weight unless otherwise indicated.
The experiments are illustrative only. and are not to be
taken by way of limitation.
For the foams prepared below, viscosities
were Zetermined using a Brookfield viscometer. Resin
samples were equilibrated in a 24C water bath prior to
viscosity measurement. Water concentration was deter-
mined by the Carl Fischer method which is well known tothose skilled in the art. Free phenol was determined
by gas chromatography using a S & M Scientific Model
5750 gas chromatograph commercially available from
Hewlett~Packard Co. K-factors were obtained using a
K-Matic thermal conductivity instrument commercially
available from Dynatech Corp. Foam Friability was
determined in accordance with ASTM C-421. Foam cell
size was determined in accordance with ASTM D-2842.
27,927A-F -16-
393
-17-
Foams were made in a mold using various
formulations as hereinaf-ter set forth. These formu-
lations were mixed and poured into the mold and placed
in an oven set at 75C for a period of 45 to 60 minutes.
The sample was then demolded and placed in a curing
oven set at 75C and left in the oven at that tem-
pe~ature for a period of about lO hours.
In the Burn-Through Test a foam sample having
a size of 2.5 cm by 15.2 cm by 7.6 cm (1 in. x 6 in. x
3 in.) is placed in a holder. A propane burner flame
having a temperature of 1,157C is introduced 2.5 cm
(one inch) above the sample and perpendicular thereto.
The time is then measured for the flame to become
visible through the bottom side of the foam opposite
the side to which the flame is applied. Penetration
of the flame is observed by use of a cut-out in a plate
on which the foam rests. The test is terminated after
30 minutes if the sample does not burn through.
.
The Autoxidation Test occurs in an oven set
at 250C. A thermocouple is placed in a foam sample
having a size of 7.6 cm by 7.6 cm by 7.6 cm (3 in. x 3
in. x 3 in.). The internal temperature of the foam is
recorded as a function of time. Samples which autoxi-
dize gave an exotherm that quickly rose above 250C.
The Autoxidation Test was terminated when the exotherm
reached 400C to avoi~d generation of obnoxious fumes.
Inasmuch as the foams were produced, as noted above, in
an 45.7 cm by 76.2 cm by 5.1 cm (18 in. x 30 in. x 2
in.) mold, the test samples for the Autoxidation Test
were prepared by gluing 7.6 cm by 7.6 cm by 2.5 cm
(3 in. x 3 in. x 1 in.) samples together.
27,927A-F -17-
~LZ493~33
-1~3-
Preparation of a Phenolic Resin of the Resole Type For
Use in Making Foams According to the Present Invention.
370 Grams of phenol and 440 grams of an aqueous
(37%) solution of formaldehyde were added to a two
liter flask fitted with a condenser and a mechanical
stirrer to form a first mixture. The pH of the first
mixture was adjusted to about 9.0 with about 6 milli-
liters (ml) of an aqueous (50%) solution of sodium
hydroxide to form a second mixture. The second mixture
was heated to 60C with stirring and maintained at that
temperature for a period of four hours. The second
mixture was then cooled to room temperature ~nd the p~
of the second mixture lowered to about 1.7 with about 9
ml of an aqueous (40%) solution of sulfuric acid to
form a third mixture. The third mixture was then
heated with stirring to 60C and maintained at that
temperature for an additional two hours. The pH of the
third mixture was then raised to 5.5 with about 4 ml of
an aqueous (5%) solution of sodium hydroxide after
cooling the third mixture to room temperature. Upon
standing, an aqueous layer separated from a resin
phase. The aqueous layer was decanted off from the
resin phase. The resin phase was then washed with an
equal volume of water. After the wash water was decan-
ted, the resin phase was vacuum stripped of additionalwater until a water content from about 8 to about 15
percent by weight, based on weight Qf resin plus water,
and a viscosity of about 3 Pa s was reached.
Experiment 1 - Low K-factor Foam Prepared in Accordance
with the Invention
27,927A-F -18-
~29~3~33
--19--
2.2 kilogramq (5 poundQ) of phenol were added
to 13.5 kg t30 poundq) of a phenolic re~ole re~in
prepared aQ detailed hereinabove to form a mixture.
The mixture wa~ then vacuum ~tripped of additional
water to a viqcosity of 7 D5 Pa~ a water content of 4O0
percent, ba~ed on mixture weight, and a free phenol
content of 13~5 percenk, ba~ed on mixing weightO A
foamable mixture waq prepared by admixing 633 gram~ of
the ~tripped mixture, 1406 gram~ of an alkyl siloxane
urfactant commercially available under the trade
de~ignation DC-193 from The Dow Corning Corporation at
Midland 9 MI 126 gram~ of polyethylene glycol
commer~ially available under the trade de ignation
Freon~ 11 and 47 gram of benzene~ulfonic acid
monohydrate (90 percAnt ~olution in water). The
foamable mixture wa~ mixed thoroughly and poured into a
45O7 cm by 76.2 cm by 5.1 cm mold and foamed a
hereinabove detailed to produce a foam Qample. After
removal ~rom the curing oven, ~he sample wa~ te~ted for
phy~lcal propertieq in accordance with the testing
methods hereinbe~ore detailed. The ample phy~ical
properties were: (a) Friability - 82 percent; (b) Foam
density ~ 46.4 kg/m3; (c) Foam cell 3ize - 0.32
25~ millimeter; and (d) Foam K-factor - 0.016 wattq/(m K).
3o
Experiment 2 - Low K-factor Foam Prepared in Accordance
With the Invention
2.7 kg of phenol were added to 18 01 kg of the
~ame phenolie reqole resin u~ed in Experiment 1 to form
27,9,27A-F -l9-
9393
-20-
a mixture. The mixture was then stripped as in Exper-
iment 1 to a viscosity of 3.4 Pa s, a water content of
6.5 percent, based on mixture weight, and a free phe~ol
content of 18.8 percent, based on mixture weight. A
foamable mixture was prepared by admixing 633 ~rams of
the stripped mixture, 14.6 grams of the same alkyl
siloxane surfactant as used in Experiment 1, 126 grams
of polypropylene glycol commer~ially available under
the trade designation P-400 from The Dow Chemical
Company, 120 grams of 1,1,2-trichloro-2,2,1-trifluoroethane,
a blowing agent, commercially available under the trade
designation Freon 113, and 47 grams of benzene sulfonic
acid monohydrate (90 percent solution in water). The
foamable mixture was then mixed thoroughly and poured
into a 45.7 cm by 76.2 cm by 5.1 cm mold and foamed as
in Experiment 1 to produce a foamed sample. The sample
physical properties were: (a) Friability - 68 percent;
(b) Foam density - 46.4 kg/m3; (c) Foam cell size -
0.58 millimeter; and (d) Foam K-factor - 0.017 watt/(m-K).
ExPeriment 3 - Low K-factor Foam Prepared in Accordance
With the Invention
160 Grams of aniline were added to 800 grams
of the same phenolic resole resin used in Experiment 1
to form a mixture. The mixture was then stripped as in
Experiment 1 to a viscosity of 4.42 Pa-s. A foamable
mixture was prepared by admixing 150 grams of the
stripped mixture, 2.25 grams of the same alkyl siloxane
surfactant as used in Experiment 1, 15 grams of the
same polyethylene glycol as used in Experiment 1, 15
grams of the same blowing agent as used in Experlment 2
and 63 grams of benzene sulfonic acid monohydra-te (90
percent solution in water). The foamable mixture was
27,927A-F -20-
~24939.:~
-21-
then mixed thoroughly and poured into a 22.9 cm by 22.9
cm by 5.1 cm mold and foamed as in Experiment 1 to
- produce a foam sample. After removal from the curing
oven, the foam sample was tested for its K-factor. The
K-factor of the sample was 0.025 watt/(m-K) when measured
initially. After a lapse of 5 weeks, the K-factor was
0.021 watt/(m-K).
Experiment 4 - Foam Prepared in Accordance With the
Invention but With a Different Sur-
factant
3.6 kg of phenol were added to 24.7 kg of the
same phenolic resole resin used in Experiment 1 to form
a mixture. The mixture was then stripped as in Experi-
ment 1 to a viscosity of 5.53 Pa s a water
content of 5.6 percent, based on mixture weight, and a
free phenol content of 19.6 per~ent, based on mixture
weight. A foamable mixture was prepared by admixing
225 grams of the stripped mixture, 6.8 grams of an
ethoxylated castor oil commercially available under the
trade designation G-1292 from Atlas Chemical, 43 grams
of the same polyethylene glycol as used in Experi-
ment 1, 43 grams of the same blowing agent as used in
Experiment 2 and 15 grams of benzene sulfonic acid
monohydrate (90 percent solution in water). The foamable
mixture was then mixed as in Experiment 1 and poured
. into a 30.4 cm by 30.4 cm by 5.1 cm mold and foamed as
in Experiment 1 to produce a foamed sample. The sample
physical properties measured were: (a) E'oam density -
48.0 kg/m3 and (b) K-factor - 0.018 watt/(m-K).
Friability and foam cell size were not measured.
27,927A-F -21-
~2~3~33
-22-
xperiment 5 - Foam Not According to the Invention
Prepared Without Adding a Solvent
and Without Adding a Polyglycol
Following Stripping
The same phenolic resole resin used in Experi-
ment 1 was vacuum stripped of water to a viscosity of
100 Pa-s and to a water content of 3.5 percent based
on weight o~ resin plus water. With mixing, 6 75 grams
of the same alkyl siloxane surfactant as used in
Experiment 1, 45 grams of the same blowing agent as
used in Experiment 1, and 31.5 grams of an acid catalyst
- mixture consisting of equal weights of 6 normal hydro-
chloric acid and ethylene glycol were added to 450
grams of the stripped resin to form a mixture The
mixture was then poured into a 10.2 cm by 30.5 cm by
30.5 cm mold and foamed as in Experiment 1 to produce
a foam sample. The sample had a K-factor of about
0.035 watt/(m-K).
Experiment 6 - Flame Penetration and Autoxidation
Tests of Foam Not According to the
Invention Prepared From a Foamable
Mixture Having a Low Phenol Content
A first mixture was formed by adding 40 grams
of phenol to 800 grams of a phenolic resole resin which
had previously been stripped to a viscosity of 2.01
Pa s and a water content of about 12 percent based on
resin weight. The mixture had a phenol content of 8.2
percent based on weight of the mixture. A foamable
mixture was prepared by admixing 150 grams of the first
mixture, 2.25 grams of the same alkyl~siloxane sur-
factant as used in Experiment-1, 30 grams of the same
27,927A-F -22-
~Z~93g3
-23-
polyethylene glycol as used in Experiment 1, 15 grams
of the same blowing agent as used in Experiment 2, and
2 grams benzene sulfonic acid monohydrate (90 percent
solution in water). The foamable mixture was then
mixed as in Experiment 1, poured into a 30.5 cm by 30.5
cm by 5.1 cm mold and foamed as in Experiment 1 to
produce a foam sample. The sample physical properties `
were: (a) Foam density - 57.6 kg/m3; (b) K-factor -
0.039 watt/(m-K). The sample had a Burn-Throùgh Time
of 1.5 minutes.
Experiment 7 - Flame Penetration Test of Foam Pre-
pared in Accordance With the Present
Invention
2.0 kg of phenol were added to 13.6 kg of the
same phenolic resole resin as used in Experiment 1 to
form a mixture. The mixture was then stripped as in
Experiment 1 to a viscosity of 7.5 Pa s, a water con-
tent of 6.25 percent, based on mixture weight, and a
phenol content of 13.9 percent, based on mixture weight.
A foamable mixture was prepared by admixing 633 grams
of the stripped resin, 14.5 grams of the same alkyl
siloxane surfactant as used in Experiment 1, 126 grams
of the same polyethylene glycol as used in Experiment
l, 120 grams of the same blowing agent as used in
Experiment 2 and 47 grams of benzenesulfonic acid
monohydrate (90 percent solution in water). The foamable
mixture was then prepared as a foam sample in the same
manner as set forth in Experiment 1. The foam sample
was then tested for physical properties as hereinbefore
detailed. The sample physical properties were: (a)
Friability - 71 percent; (b) Foam density - 43.2 kg/m3;
(c~ Foam cell size - 0.41 millimeters; and
(d) Foam K-factor - 0.019 watt/(m-K).
27,927A-F -23-
~Z~33~3
-24-
The sample had a Burn-Through Time
of greater than 30 minutes. In addition, the sample
passed the Autoxidation Test by exhibiting no exotherm
in an oven heated to a temperature of 250 Centigrade.
Experiment 8 - Flame Pene-tration and Autoxidation Tests
of Foam Not According to the Invention
With 5 Percent Polyglocol
2.7 kg of phenol were added 18.1 kg of the
same phenolic resole resin as used in Experiment 1 to
form a mixture which was then stripped, as in Experiment 1,
to a viscosity of 3.45 Pa s, a water content of 6.5
percent, based on mixture weight, and a phenol content
of 18.8 percent, based on mixture weight. A foamable
mixture consisting of 633 grams of the stripped resin,
14.6 grams of the same alkyl siloxane surfactant as
used in Experiment 1, 31.5 grams of the same polyethylene
glycol as used in Experiment 1, 120 grams of the same
blowing agent as used in Experiment 2, and 47 grams of
benzene sulfonic acid monohydrate (90 percent solution
in water) was then mixed with stirring. The foamable
mixture was then prepared as a foam sample as in Experi-
ment 1. The foam sample was then tested for physical -
properties as hereinbefore detailed with the following
results: (a) Foam density - 44.8 kg/m~; (b) Foam cell
size - 0.81 millimeter; and (c) Foam K-factor - 0.038
watt/(m-K). The sample had a Burn-Through Time of 1
minute. In the Autoxidation Test, the sample had an
exotherm of 312C in a 250C oven.
Experiment 9 - Flame Penetration and A~toxidation Tests
of Foam According to the Invention
Prepared With 10 Percent of a Polyglycol
27,927A-F -24-
< ~ 3~3
-25-
A foam sample was prepared using the same
components and procedures as in Experiment 8, except
that the amount of polyethylene glycol was doubled.
Physical properties of the foam sample so prepared
were: (a) Foam density - 33.6 kg/m3; (b) Foam cell
size - 0.67 millimeter; and ~c) Foam K-factor -
0.021 watt/(m K). The sample had a Burn-Through
Time of 21 minutes. In the AUtoxidation Test, the
sample exhibited no exotherm in a 250C oven.
0 Experiment 10 - Flame Penetration and Autoxidation
Tests of Foam According to the
Invention Prepared With 20 Percent
of a Rolyglycol
A foam sample was prepared using the same
components and procedures as in Experiment 8 except
that the amount of polyethylene glycol was quadrupled.
Physical properties of the foam sample so prepared
were: (a) Friability - 54 percent; (b) Foam density -
44.8 kg/m3; (c) Foam cell size - 0.67 millimeter; and
(d) Foam K-Factor - 0.017 watt/(m-K). The sample had
a Burn-Through Time of greater than 30 minutes. In
the Autoxidation Test, the sample exhibited no exo-
therm in a 250C oven.
Experiments 11-14 - Burn-Through Evaluation
Foams prepared in the same manner as those
prepared in Experiments 7-10 above but with varying
levels of phenol and polyglycol were evaluated for
Burn-Through Time. The results of such evaluations
are presented together with the Burn-Through Times
for Experiments 6-lO above in the following table.
27,927A-F -25-
~Z~9393
-26-
- Burn-Through
Experiment % % Time
No. Phenol* Polyglycol* (Minutes)
6** 8.2 20 1.5
7 13.9 20 30+
8** 18.8 5 1.0
9 18.8 10 21
18.8 20 30~
11** 4.2 20 1.25
1012** 13.9 20 1.5
13 21.4 20 30+
14 23.4 20 30+
* sased on weight of resin.
** Comparative Experiment, not an example of the inven-
tion.
An examination of the data presented in the
foregoing table illustrates that a total phenol con-
tent of 13.9 percent based on weight of resin repre-
sents a threshhold level at a 20 percent level of
polyglycol also based on weight of resin. By total
phenol content, it is to be understood that this
quantity is the amount of solvent plus phenol remain-
ing after stripping. The data further illustrates
that foams having a Burn-Through Time of greater
than 10 minutes are produced at a polyglycol level
of about 10 percent at a total phenol content.of
18.8 percent. Persons skilled in the-art wilI
recognize that optimal amounts of polyglycol and
phenol may vary depending upon the phenol or the
polyglycol used in making the foam but that such
amounts are readily ascertainable.
27,927A-F -26-
lL2~93~33
-27-
An examination of the foregoing Experi-
ments 1-14 amply illustrates the advantages of the
present invention. Foams having a generally closed
cell structure and a K-factor of less than 0.029,
preferably in the range of from 0.017 to 0.024
watt/(m-K~ are readily produced. In addition, by
combining solvent and polyglycol, foams are pro-
duced which, in addition to having the aforemen-
tioned K-factor and cell structure, exhibit marked
resistance to flame penetration and to autoxida-
tion.
Similar results to the foregoing are
produced with other solvents, polyglycols, surfac-
tants and catalysts, all as detailed hereinabove.
27,927A-F -27-
