Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
(1) Field of The Invention
This invention is directed to condensation products and
methods for the preparation of condensation products of phenol,
urea, and formaldehyde which provide cellular plastic compositions
useful as insulation material.
(2) Description Of The Prior Art
.
Heretofore, foamed materials derived from condensates of
a phenol and formaldehyde have been prepared by mixing a liquid
phenol-formaldehyde resin, a blowing agent, optionally a surfac-
tant, and then a curing (i.e., hardening) agent, such as a strong
acid, and applying heat to volatilise the blowing agent and harden
the resin.
Such compositions and the methods of their preparation
posed obvious disadvantages, particularly if large sections of
rigid, foamed condensates were required. Big ovens or a large
number of infra-red heaters were required to supply heat evenly
over the whole surface. Since the foams possessed good heat-insu-
lating properties, it was very difficult to supply heat to the in-
terior of a large block of the foamed condensate. Irregular heat-
ing resulted in a non-uniform foam which was unsuitable for the
purpose for which it was intended and which was structurally weak.
Since external heaters or ovens are required to obtain a satisfac-
tory rate of hardening, ("on-site") preparation of foams was diffi-
cult, or even impossible, and this was a further disadvantage of
such compositions and methods.
In attempts to overcome these drawbacks, other substan-
ces have been included in the resin mixture which react exothermi-
cally with the curing agent and thus reduce or remove the need for
applying heat to cure the resin. Solid substances which have been
so used include phosphorus pentoxide, barium oxide, and calcium
carbonate. However, such exothermically-reacting substances are
sometimes unpleasant to handle on an industrial scale, ~e foams
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contain inert materials which add to the weight of the product,
but serve no useful purpose, and since the unfoamed starting mix-
tures contain sol~dis, it is difficult to obtain uniform suspensions,
which will give uniform foams. This is especially true if a con-
tinuous method of foaming is employed. Alternatively, as shown
by United States patent 3,692,706, liquids have been added which
react exothermically to form a polymer under the influence of the
curing agent. However, even the use of this expedient does not
solve the major drawback of all these systems which is that they
all require a chemical blowing agent. In other words, the phenol-
formaldehyde resins cannot be foamed, placed, and set by simple
mechanical agitation and pumping.
While insulation materials based on condensates of urea
and formaldehyde have been foamed, placed and set by simple me-
chanical agitation and pumping, such materials have unsatisfac-
tory to poor chemical and physical properties for many thermal and
acoustical insulation uses for which such condensates are intended.
For example, such condensates have poor compressive strength, ten-
sile strength, shear strength and their water solubility is too
high for many insulation uses for which they are intended in the
building industry. In addition, their flame spread characteristic
is higher than desirable for many applications in the building
industry where safety is an important feature.
Mixtures of phenol-formaldehyde and urea-formaldehyde
condensates and certain urea-phenol-formaldehyde condensates are
known in the art, see United States patents 3,077,458 and
3,549,473~ but these materials have characteristics restricting
their use to liquid films or binders.
SUMMARY OF THE INVENTION
It has now been found that an excellent thermal and
acoustical insulation material having vastly superior tensile
strength, shear strength, compressive strength and water repellency
and much lower fuel contribution, and flame spread compared to
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prior art compositions can be obtained by pr~paring a phenol-urea
formaldehyde resin in which the phenol content of the resin varies
from about 1 to about 20 percent by weight of the total resin
content and which is maintained at a pH of about 6 to about 8
after the suitable degrees of reaction have been accomplished.
Thus~ the present invention provides condensation
products and methods for the preparation of condensation products
of phenol-urea and formaldehyde which form foamed cellular composi-
tions where, in the condensation product, the phenol is present
in the amounts of from about 1 to about 20 percent by weight, the
urea is present in the amount of from about 23 to about 48 percent
by weight, and the formaldehyde is present in the amount of from
about 42 to 70 percent by weight, the ratio of formaldehyde to
urea being in the range of from about 1 to about 3 parts
formaldehyde to about 1 part urea, said condensation product
having a viscosity at room temperature in the range of about 30
to 36 seconds on a No. 1 Zahn cup prior to the commencement of
setting and a pH maintained in the range of from about 6 to about
8 prior to the commencement of setting
DESCRIPTION O~ THE INVENTION
.
The following indicates how typical compositions
according to the invention may be produced.
Generally, an aqueous solution of uninhibited formalde-
hyde is first charged into a suitable vessel containing an
agitator, a closed hot water system, and a cooling condenser.
This is preheated to temperatures in the range of about 15 to
80C preferably about 30C and the pH is adjusted with a basic
or caustic solution, such as sodium hydroxide, to about 7. Alter-
natively, the compositions of this invention may be produced by
starting with an aqueous solution of urea-formaldehyde reaction
products commercially available under the trade name "U.F.
Concentrate-85"; "U.F. Concentrate-85" is a clear, colorless,
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viscous liquid composed of formaldehyde, urea, and a small amount
of water which is believed to be a mixture of methylolureas and
formaldehyde. It contains about 15% water and approximately 85%
solids, the latter combined in a formaldehyde to urea mol ratio
of about 4.8 to 1. The "U.F. Concentrate-85" is charged into a
suitable vessel containing an agitator, a closed hot water system, -~
and a cooling condenser. This is diluted on an approximately 1:1
basis by weight with water and then preheated to temperatures in
the range of about 15 to 80C, preferably about 30C, and the pH
adjusted with a basic or caustic solution to about 7.
Thereafter, the appropriate parts by weight of phenol
are added in amounts necessary to achieve the desired weight
percent of phenol in the end product and the pH is again adjusted
with the base to maintain it at about 7. The urea or additional
urea to be incorporated in the final product is added and the
mixture is agitated to dissolve the urea, usually from about 10
minutes to about an hour, depending on the amount of urea added,
at ambient temperature, i.e., about 30C. Then the mixture is
heated and reacted under constant agitation at reflux (98C to
100C) for approximately 15 minutes up to about an hour. At
the end of this period and maintaining this temperature, an ;
aqueous formic acid solu~ion containing up to as much as about
20 percent formic acid (HCOOH) is added slowly over a period of
time, usually 45 minutes, until the desired amount of formic acid
is present in the reacting mixture, and until the reactl~on mix-
ture is brought down to a pH of between 6 and 4.4, preferably
about 5.5. While maintaining a temperature of approximately 100C
and constant agitation, viscosities are taken at intervals of 5
minutes, When the viscosity reaches approximately 30 seconds on
a No. 1 Zahn cup, the reaction may be concluded as described
hereinafter, depending on the product characteristics desired.
However, should a condensation product of higher
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viscosity be desired, the following simple test of water solu-
bility is helpful as a preliminary quick indication of viscosity.
A small quantity, such as .25cc., is taken [by pipette] from the
reaction mixture at intervals of 2 minutes and dropped into a
beaker of distilled water at a temperature of 15C. When droplets
of the reaction mixture are observed to form a slight white cloud,
the viscosity should be about 31.5 to 32 seconds on the No.l
Zahn cup. Should a still higher viscosity be desired, a lOcc.
sample of the reaction mixture can be taken at intervals of about
2 minutes. When mixing this sample with 40cc. of distilled
water at 15C yields a dense white cloud, the viscosity should be
about 32.5 seconds. I~ the reaction is continued the condensate
will become more viscous yielding even more opaque mixtures.
More elaborate measurement techniques are also available, involving
measurement of ohmic resistance/electrical conductivity or index
of refraction.
The final viscosity of the condensate should be in the
range of about 30 to about 36 seconds on a No. 1 Zahn cup. The
viscosity can go up as high as 40 seconds, but the condensate
should then be cut with water to bring the viscosity down to the
desired range. For most end uses a viscosity of about 32.5
seconds is optimum.
When the desired final viscosity is reached, the mixture
is cooled down rapidly and neutralized with a basic or caustic
solution, such as sodium hydroxide, and removed from the reaction
vessel. The final pH of the reaction product should be maintained
at between 6 and 3, preferably at about 7.
The phenol-urea-formaldehyde resins of this invention,
having viscosities and pH values in the ranges mentioned above,
have long shelf lives of from over 2 to over 6 months and can be
pumped mechanically through orifices as small as lmm , whereupon
they set up extremely rapidly, in the order of about 5 to 150
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seconds, depending on viscosity and age of condensate, to provide
superior stable cellular thermal and acoustical non-combustible
insulation particularly suited for cavities in building wall
systems, masonry, foundations, slabs, and roofs.
Conventional foaming agents, hardening agents, etc.,
known in the phenol-formaldehyde and urea-formaldehyde art can be
used in carrying out the invention. Optionally, conventional
blowing agents known in the phenol-formaldehyde and urea-formald-
hyde art may be used if desired but they are not necessary for
utilization of the invention described herein.
The following specific examples illustrate the prepara-
tion of a phenol-urea-formaldehyde resin according to the present
invention in which the weight percent of phenol in the final raw
condensation product is approximately 2 percent in Example 1 and
approximately 15 percent in Example 2.
EXAMPLE 1
8.4 parts by weight of 37 percent uninhibited HCHO
(formaldehyde) is charged into a suitable veqsel containing an
agitator of low rpml a closed hot water system and cooling con-
denser, and is preheated to 30C. The pH is normally 4.6 to 5ØThis is adjusted by means of a 1 to 4 normal NaOH solution until
a pH of 6.8 to 7.0 is obtained. .114 parts by weight of phenol
of approximately 95% solution is added to the formaldehyde solu-
tion at 30C. The pH is again checked and adjusted to 7Ø
Immediately upon this neutralization, 3 parts by weight of dry
urea (industrial grade) is added to the mixture now under con-
stant agitation. This is agitated for a period of approximately
10 minutes to dissolve the urea. At this point the mixture is
heated by means of a closed hot water system capable of producing
temperatures up to 120C or by other means of producing this temp-
erature, for example, an ethylene glycol bath. The mixture is
then heated under constant agitation to reflux (98 to 100C) and
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reacted for a period of 15 minutes. At the endiof this period and
maintaining this temperature, a 10% solution of HCOOD (formic
acid) is slowly added over a period of 30 to 45 minutes to bring
the reaction mixture down to a pH of 5.5.
While maintaining 100C and constant agitation, viscosi-
ties are taken at intervals of 5 minutes. When viscosity reaches
approximately 30 seconds on a No. 1 Zahn cup, a small quantity,
such as 25cc, is taken from the reaction mixture and dropped into
a beaker of distilled water at a temperature of 15C and is
observed. This test is-for water solubility and when droplets of
the reaction mixture start to form a slight white cloud, the
viscosity should be about 31.5 to 32 seconds on a No. 1 Zahn cup.
If the viscosity exceeds this, water is added slowly as not to
stop reaction, and viscosity is brought to this point. The water
solubility test is then taken at intervals of 2 minutes. When the
resin forms a dense white cloud, the viscosity should be about
32.5 seconds, i.e., the desired viscosity. Here 10cc of reaction
mixture is taken and mixed with 30cc distilled water at 15C.
This solution should form a smooth, white opaque cloud mixture.
20 If not, the reaction is continued untll opaque mixture is obtained.
At this point the mixture is cooled down rapidly and neutralzied
to a pH of 7.0 with a solution of 2 normal NaOH and removed from
the reaction kettle.
EXAMPLE 2
8 4 parts by weight of 37~ uninhibited HCHO (formalde-
hyde) is charged into a suitable vessel containing an agitator
of low rpm, a closed hot water system and cooling condenser, and
is preheated to 30C. The pH is normally 4.6 to 5Ø This is
adjusted by means of a 1 to 4 normal NaOH solution until a pH of
30 6.8 to 7.2 is obtained. 1.311 parts by weight of phenol of
approximately 95% solution is added to the formaldehyde solution
at 30C. The pH is again checked and adjusted to 7Ø Immediate-
ly upon this neutralization, 3 parts by weight of dry urea (indus-
trial grade) is added to the mixture now under constant agitation.
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This is agitated for a period of approximately 10 minutes to dis-
solve the urea. At this point the mixture is heated by means of
a closed hot water system capable of producing temperatures up to ;
120C or by other means of producing this temperature, for example,
an ethylene glycol bath. The mixture is then heated under constant
agitation to reflux (98 to 100C) and reacted for a period of 15
minutes. At the end of this period and maintaining this tempera-
ture, a 10% solution of HCOOH (formic acid) is slowly added over
a period of 30 to 45 minutes to bring the reaction mixture down.
to a pH of 5,0. The reaction is continued at 100C and maintain- ~ .
ing constant agitation until an opaque mixture is obtained with
the water solubility tests described in Example 1. At this point
the mixture is cooled down rapidly and neutralized to a pH of 7.0
with a solution of 2 normal NaOH and removed from the reaction
kettle.
The chemical and physical properties of these resins are
set forth below in tabular form and compared against a cemmercially
available urea formaldehyde resin. In both resins the same type
of foaming agent, i.e., an aqueous detergent mixture expanded by
air was utilized.
Phenol-Urea-Formaldehyde
Urea-FormaldehydeResin
Resin Example 1 Example 2
Compressive Strength 4 9 17
(lbs./in.2)
Tensile Strength 1 3.2 4.7
(lbs./in.2)
Shear Stren~th 2 5.5 6.3
(lbs./in. )
Dsnsity 3 0.6 0.9 1.6
(lbs./ft. )
Toxicity Non-toxic Non-toxic Non-toxic
Water Transmission (%) 3 1 <1
Flame Spread 25 5 0-5
Smoke Contribution 0 to 5 5 5 to 10
Fuel Contribution 10 0 0
Water Absorbancy/ 11-1/2 3-1/2 2-1/2
24. Hr. (by weight)
Heat Disintegration50 sec. 3 min 29 sec. 4 min.
(complete)
3" x 3" x 2"
at 3,600F
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The resins of this invention containing from about 1
percent to 2,0 percent phenol by weight give exceptionally excel- -
lent results for in-place foaming such as cavity fill for thermal
and acoustical insulating foam. At these percentages of phenol,
the products in a foam state have greatly reduced surface burning
characteristics over the normal urea formaldehyde foams.
From about 2 percent to 5 percent phenol in the final
raw condensation product provides finished foam products which
have much greater compressive strengths for foam in-place cavities
and also greatly reduces moisture transmission over conventional
urea-formaldehyde products, in fact in many cases where the foam
product is used, a vapor barrier may be omitted.
Foamed products upon curing containing from 5 to about
10 percent phenol achieve compressive strengths of approximately
10 to 15 lbs./in.3, thus finding utilization in the form of boards.
Their shear strength is also greatly increased. The products are
particularly highly resistent to flame spread. At these percent-
ages the product also may be formed into pipe coverings which have
excellent thermal insulation properties.
Foamed products containing from about 10 percent to
about 20 percent phenol by weight are very heavy, normally having
densities between 1u6 and 3.5 lb~/in.3. They may used in place
of styrene and urethane boards and are desirable because of their
high resistance to flame. Such products are also much more water
repellent that urea formaldehyde foams. At this range of phenol
concentration, the use of additional foaming agent and increasing
pressure allows one to foam the product without the need to add
blowing agents.
Above these percentages of phenol, even with an increase
30 in foaming agent and pressure, foaming by mechanical means is im-
possible or extremely difficult at ambient temperatures, which are
the normal temperatures for application of these materials.
The resins of this invention are normally foamed at the
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site of use by using a portable applicator equipped with flexible
hose for delivering expanded wet foam to areas to be insulated. -
Drying time depends on thickness, temperature, humidity, and the
amount of ventilation. Under average summer conditions with
normal attic ventilation, a 2" thick application will dry within
3 days. Winter temperatures do not affect the foaming process
provided solution temperatures are kept above 50F during applica-
tion. ~-
Certain changes may be made in the compositions and
processes herein desc~ibed without departing from the scope and '
teachinys and it is intended that all matter contained in the
description is by way of illustration rather than limitation.
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