Note: Descriptions are shown in the official language in which they were submitted.
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STABLE BISPHENOLIC COMPOSITIONS
FIELD OF THE INVENTION
This invention relates to a method of manufacturing a stable solution
containing
bisphenolic stillbottoms. This invention also relates to phenolic compositions
that are
manufactured using solutions of bisphenolic stillbottoms. This invention
further relates
to phenolic compositions that are useful in the manufacture of laminates and
paper
products.
BACKGROUND OF THE INVENTION
Bisphenol A stillbottoms, as one example of bisphenolic stillbottoms known in
the art, are produced by dehydrocondensing phenol and acetone in the presence
of a
strong acid catalyst. When bisphenol A is separated from the reaction mixture
by
distillation, for example, or by other purification methods, there is a
material remaining
that has been generally described in the art as a bisphenol stillbottom.
Consistent with
the use of the term in the art, hereinafter, the term bisphenol stillbottoms
refers to that
material separated during the preparation of bisphenol that is not purified
bisphenol.
Thus, bisphenol A stillbottoms may contain some bisphenol A. The bisphenol A
stillbottom typically contains, in predominant proportions, other phenol-
acetone reaction
products. Dihydroxydiphenylpropane isomers and chromane compounds are
typically
present in lesser amounts.
The reuse of bisphenolic stillbottoms is generally quite limited. Bisphenolic
stillbottoms are a solid at room temperature and typically must be kept in a
molten state,
or processed into a small particle such as a flake or powder, if the
stillbottoms are to be
further used in most manufacturing processes. Molten stillbottoms are subject
to
degrading oxidation. Therefore, the chemical composition of the stillbottoms
will
change as function of the length of storage time in the molten state. As a
result of this
changing chemical composition, products made using molten stillbottoms may
have
unpredictable properties. The processing of stillbottoms into an intermediate
form, such
as a flake or powder, adds significant cost to products made using this
intermediate form
and a flake or powder may sinter. Therefore, typically, bisphenolic
stillbottoms are
incinerated for disposal.
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The use of bisphenolic stillbottoms in phenolic resin compositions has until
now
been limited. Not surprisingly, because phenolic resins are typically
condensed from
aqueous solutions, the insolubility of bisphenolic stillbottoms generally
makes their use
prone to problems. In one prior art process, for example, bisphenol A
stillbottoms must
be further refined before they are useable in the synthesis of a novolac
resin. In this
process, bisphenol A stillbottom are further processed, at extreme
temperatures, reduced
pressures and in the presence of an alkaline catalyst, to recover phenol and
isopropenyl
phenol. A residue remains after such processing and this residue is said to be
useful in
the manufacture of novolac resins.
The use of bisphenols in phenolic resin synthesis in the prior art is
surprisingly
limited. As described above with respect to bisphenol stillbottoms, the
relative
insolubility of bisphenolic compounds generally makes their use prone to
problems. For
example, in one prior art composition, alkylidenepolyphenols, together with a
trifunctional phenol and formaldehyde, are used in the synthesis of resoles.
However, as
the prior art provides, the timing of the addition of the alkylidenepolyphenol
is critical.
The alkylidenepolyphenol can be added neither at the start of the synthesis
nor near the
end of the synthesis, but must be added at some mid-point in the reaction
sequence.
One prior art process describes a resin that is the reaction of product of
formaldehyde
and bisphenol A. However, as the prior art teaches, it is essential to
maintain a very
narrow mole ratio of formaldehyde to bisphenol A. Resins of this type have
limited
application as leveling compounds or metal coating compounds.
The preparation of aqueous solutions of bisphenolic stillbottoms, let alone
the
use of these aqueous solutions in the manufacture of resins, until now has
been unknown
in the art. It has been generally concluded in the prior art that bisphenolic
stillbottoms
do not form stable aqueous solutions. It has been taught in the prior art that
bisphenol
A, for example, forms a two-phase system with hot water. It is known that
molten
bisphenol A forms a two-phase system with water at temperatures even as high
as 85°C
to 100°C. In fact, it has long been known in the art that water washing
of phenolic
mixtures is one means to recover a relatively pure phenol product. The water
will
dissolve inorganic salts and acid impurities, while the phenolic product
readily separates
from the aqueous solution.
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The development of methods that would allow reuse of bisphenolic stillbottoms
have understandably been the object of few prior art attempts. One prior art
process
provides an aqueous suspension of ultrafine bisphenol particles. Strongly
alkaline
compounds are used in the preparation of such a suspension. This suspension is
used in
the preparation of polycarbonates. Yet another prior art process uses strongly
alkaline
compounds, such as sodium hydroxide, to provide for the dissolution of
bisphenol A in
hot water. In this prior art process, purified bisphenol A may be recovered
from a
bisphenolic mixture. Fractions of the bisphenolic mixture will dissolve in the
hot water
in increasing amounts as the amount of sodium hydroxide is increased. Purified
insoluble bisphenol A is recovered by separation from the liquid portion that
contains
the soluble fractions. Still another prior art process employs a co-solvent,
such as an
alcohol, to provide for the dissolution of diphenols in water. In this prior
art process
bisphenol A is said to dissolve in a water/alcohol solution that has been
heated to reflux.
This process is said to be useful in the purification of bisphenol A.
Each of the prior art processes has disadvantages. A heterogeneous two-phase
system of bisphenolic stillbottoms and water is an impractical composition
both for the
storage of bisphenolic stillbottoms and the use of the stillbottoms in the
synthesis of
resins. Likewise, the use of strongly alkaline materials or co-solvents
adulterates the
bisphenolic stillbottoms thus limiting the further use of the modified
stillbottoms. The
use of molten bisphenolic stillbottoms can result in degradation of the
bisphenolic
stillbottoms thus affecting the properties of resins made using such
stillbottoms. Pre-
processing the bisphenolic stillbottoms into a flake or powder is costly.
Furthermore,
flakes or powders must be re-dissolved during the synthesis of a resin in
order for the
flake or resin to participate in the synthesis. The re-dissolution presents
yet an
additional energy requirement. Purification of the bisphenolic stillbottoms to
another
form is an energy intensive process that changes the chemical composition of
the
bisphenolic stillbottoms, thus further limiting the utility of the modified
form.
It would therefore be advantageous to have a stable aqueous solution of
bisphenolic stillbottoms thus obviating the need to store bisphenolic
stillbottoms in a
molten state or to further process bisphenolic stillbottoms into a flake or
powder form.
It would also be an advantage to have a phenolic resin composition that
included in the
manufacture of the phenolic resin the use of a stable aqueous solution of
bisphenolic
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stillbottoms. It would be a further advantage to have a process for using
bisphenolic
stillbottoms in the synthesis of phenolic resins that did not require
refinement of the
bisphenolic stillbottoms into another chemical form.
The preparation of laminates and resin-impregnated papers using phenolic
resins
is also known in the art. The resins used in such preparations range from low
molecular
weight resins having a high tolerance for water to high molecular weight
resins having a
low tolerance for water.
The preparation of laminates and resin saturated papers using phenolic resins
based on the prior art has attendant disadvantages. Low molecular weight
resins are
typically prepared by using a high phenol to formaldehyde ratio, or, in the
alternative, a
low formaldehyde to phenol ratio. Such resins typically contain a high free
phenol
content. These resins, accordingly, exhibit high emissions when subjected to
the
elevated temperatures realized in the manufacture of laminates.
It would therefore be an advantage to have a low cost process for producing
low
molecular weight resins that also contain low amounts of residual free phenol.
It would
be a further advantage to have a product of such a process.
SUMMARY OF THE INVENTION
The present invention provides a stable aqueous solution of bisphenolic
stillbottoms. The present invention also provides a resole composition that
includes in
the manufacture of the resin the use of a stable aqueous solution of
bisphenolic
stillbottoms. The present invention further provides a process for using
bisphenolic
stillbottoms in the synthesis of phenolic resins that does not require
refinement of the
bisphenolic stillbottom into another chemical form.
The present invention provides a low molecular weight phenolic resin that
exhibits improved paper saturation and reduced phenol emissions during
treating when
compared to the prior art. The present invention also provides a method for
making low
molecular weight phenolic resins that provide improved paper saturation and
reduced
phenol emissions during treating when compared to the prior art.
The present invention further provides a resin, and a method for making such a
resin, that results in a paper laminate that can provide improved flexibility
when
compared to the prior art.
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DETAILED DESCRIPTION OF THE INVENTION
According to one embodiment of the present invention, a single-phase
composition of bisphenolic stillbottoms is prepared by mixing water and
bisphenolic
stillbottoms together under controlled conditions. Surprisingly, it has been
determined
that when water is mixed with molten bisphenolic stillbottoms, under reflux
conditions a
stable composition results. Such a composition is a single-phase solution at
temperatures as low as 75°C, and a single-phase composition that is a
semi-solid
ranging from a wax-like to a tar-like consistency at room temperature. The
single-phase
semi-solid can then be reheated to form a single phase liquid.
The preparation of commercial bisphenolic compounds typically involves a
distillation step whereby a purified bisphenolic compound is recovered and a
residual
bisphenolic stillbottom is separated from the recovered product. The
bisphenolic
stillbottom may also be described as a distillation residue. As is known in
the art, the
bisphenolic stillbottom exhibits different chemical properties, including
reactivity, as
compared to the remainder of the feedstock representing the purified products.
Bisphenolic stillbottoms useful in the process of the present invention may
include
bisphenol A stillbottoms. It is generally known in the art that bisphenol A
has a purity
of at least 98%, on a weight basis and that bisphenol A stillbottoms are of a
lesser
purity. As noted above, it is also known in the art that bisphenolic
stillbottoms exhibit
different chemical properties, including reactivity, than bisphenol A, for
example.
Bisphenol A stillbottoms are commercially available. One source for such
stillbottoms is General Electric Company, Plastics Group, Schenectady, New
York,
under the trade name V-390 PHENOLIC EXTENDER ("V-390"). V-390 is a mixture
of products produced during the manufacture of bisphenol A. V-390 is also
known
under the synonyms and trade name: BPA tar, BPA isomers, and LE 390 PHENOLIC
EXTENDER. V-390 has a melting point range of from about 62°C to
about 110°C
(about 144°F to about 230°F).
An alternate source for Bisphenol A stillbottoms is Aristech Chemical
Corporation, Pittsburgh, Pennsylvania under the product name BPA HEAVIES. BPA
HEAVIES is a mixture of Bisphenol A, o,p-Bisphenol A isomers, and phenol. BPA
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HEAVIES is also known under the synonyms: 4,4'-Isopropylidenediphenol, and
Bisphenol A bottoms. BPA HEAVIES begin to melt at about 62°C (about
144°F).
Table 1, provided below, characterizes a typical bisphenolic stillbottom
composition the composition of the present invention.
Table 1.
Component Estimated Concentration
p,p-Bisphenol A 10% - 84%
o,p-Bisphenol A 0% - 30%
Trisphenol 10% - 25%
Chroman-I 0% - 3%
Phenol 0% - 25%
Other Phenol-Acetone 45% - 75%
Reaction Products
The percentages listed in Table 1 are on a weight-per-weight (w/w) basis
calculated on
the total weight of the bisphenolic stillbottom. It is understood that the
component
amounts will add up to 100 percent. It should also be evident from the data of
table 1,
that the bisphenolic stillbottoms of the present invention may contain
substantially non-
bisphenol A components.
In contrast to the biphenolic stillbottoms of the present invention, bisphenol
A
melts at 150 - 155°C. Thus, it can be seen that the composition of
bisphenolic
stillbottoms, as used herein, is significantly different from the purified
bisphenol product
from which the bisphenolic stillbottom is separated.
The present invention provides a composition that is substantially lower in
cost
than bisphenol A. Because the composition of the present invention is a
stable, single-
phase, composition, it is readily used in the synthesis of resins. in place of
bisphenol A,
as illustrated by the following examples.
Stable Aqueous Solutions of Bisphenol Stillbottoms
In one embodiment, the bisphenolic stillbottoms are first brought to a molten
state. This is accomplished in a vessel to which heat may be applied. Once the
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bisphenolic stillbottoms are in a molten state water is then added to the
vessel
containing the molten bisphenolic stillbottoms. The weight of water added to
the vessel
is from about 1 % to about 20% based on the combined weight of water and
bisphenolic
stillbottoms. Because the temperature of the molten bisphenolic stillbottoms
may be
near or above 100°C, the atmospheric boiling point of water, it is
preferred that the
vessel containing the molten stillbottoms be so equipped to reflux the water
vapor that
may evolve from the vessel. The water and the molten bisphenolic stillbottoms
are then
mixed, for about 30 minutes to about 120 minutes, until a single-phase
solution is
formed.
In a preferred embodiment, the bisphenolic stillbottoms are heated to about
110°C and water is slowly added, under mixing, over about 15 to 30
minutes. The
temperature of the resulting solution is allowed to drop to about 80 to
90°C.
A typical mixing process is described as follows. Components, including the
bisphenolic stillbottoms and water, are introduced into a 1 liter four-necked
round-
bottom flask. The flask is fitted with means to stir the flask contents, means
to monitor
the temperature of the flask contents, and means to reflux volatile components
and
products. Reflux is typically afforded by use of a reflux condenser fitted to
one opening
of the four-necked flask. The condenser is typically cooled using water.
Components
are pre-weighed before addition to the four-necked flask. The flask contents
are heated
by an electric heating mantle that is controlled by a rheostat, or by use of a
steam table
so that specific temperatures may be reached and maintained. Other
arrangements will
be known to those skilled in the art.
Different diluents have been studied for use in preparing solutions of
bisphenolic
stillbottoms. Table 2, below, provides data on experiments conducted to
determine the
compatibility of such diluents. Also included is stability information in
terms of the
temperature and amount of time over which the solutions were held.
Table 2.
A Comparison Of Different Diluents For Bisphenolic Stillbottoms
Water Acetone/ Acetone Acetone
Diluent Water
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Compatibility Good Good Good Good
Weight of Diluent 10 20/10 26 20
Hold temperature C 80 25 25 32
Hold time, days 6 6 >11 >7
In a further study of the compatibility of bisphenolic stillbottoms with
various
solvents, the data of table 3, below, was collected. In these tests, the
bisphenolic
stillbottom was heated to about 90 to 110°C and the diluent was then
slowly added,
under mixing, over a ~ to 10 minute period of time. Mixing was continued for
one hour
and the solutions were allowed to cool to room temperature. The number of
phases
exhibited were observed both at the elevated temperatures and at room
temperature.
Table 3.
A Comparison Of Different Diluents For Bisphenolic Stillbottoms
Amount, grams
Component: a b c d a f g b I
V-390 450 450 450 450
BPA HEAVIES 450 450 450 450 450
Phenol 50 50
MEK' S0 ~0
IPAZ 50 50
Toluene 50 50
Water 50
I MEK is methylethylketone
2 IPA is isopropyl alcohol
All of the solutions studied appeared homogeneous under mixing. Solutions a,
c, e, g, and I exhibited homogeneity at both the elevated temperatures
(90°C - 100°C
and at room temperature. Solutions b. d, f, and h showed exhibited
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homogeneity at the elevated temperatures but showed separation into two phases
upon
standing and cooling to room temperature.
Certain analytical tests may be employed to characterize the stable
compositions
of the present invention. These tests are described below.
Cone and Plate Viscositv Determination
Aqueous solutions of bisphenolic stillbottoms were tested for viscosity.
Viscosity was determined using the well known cone and plate viscosity method.
The
cone and plate viscosity is a high shear viscosity that may be measured on a
viscometer
such as the Brookfield cone and plate viscometer, model 2000H. The Cone and
Plate
viscometer provides viscosity measurements of small samples utilizing a
thermostatically controlled fixed flat plate and a rotating cone. Typically,
values
measured by the viscometer are converted into centipoise. The cone and plate
viscosity
results reported below were made at a temperature of 75°C.
Water Content Determination
The water content of the stable aqueous solutions of the present invention
were
determined using the standard test method for water by the well known Karl-
Fischer
titration. This method uses Karl-Fischer reagent which is suitable for
determining free
water and water of hydration in most solid or liquid organic compositions and
for a wide
range of concentrations (I.e. from a parts per million order of concentration
to pure
water). This method is also known under the American Standard for Testing
Materials
method ASTM E 203-86.
The following examples serve to illustrate one embodiment of the present
invention.
Stable Solution Preparation - Example 1
A 90% aqueous solution of bisphenolic stillbottoms, based on the total
solution
weight, was prepared as follows. In this example, the atmosphere in the flask
was air,
however, other atmospheres, such as nitrogen, may be used. To a flask fitted
with a
means for mixing and a means for reflux as described above, PHENOLIC EXTENDER
V-390 ("V-390") was charged. The V-390 was heated from ambient room
temperature
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to 125°C (257°F) over a period of 55 minutes, under mixing. At a
temperature of 95
125°C (203 - 257°F) V-390 is molten. Although not considered
critical to the methods
of the present invention, the molten V-390 was mixed for 5 minutes. After
mixing the
molten V-390 for five minutes, water was added to the flask in an amount that
was 10%,
on a weight basis, of the combined weight of the V-390 and the water. The
temperature
of the water at the time of addition was nominally 25°C (77°F)
and the water was not
heated prior to adding it to the flask, although this is not considered a
controlling
variable. Mixing was maintained during and after the addition of the water.
The water
immediately began to boil and the temperature of the flask contents rapidly
dropped to
100°C (212°F). With mixing, and during the first 20 minutes
following the addition of
the water, the V-390 and the water maintained separate phases. After about 60
minutes,
the temperature of the flask contents had decreased to about 95°C
(203°F), under reflux,
and the flask contents now appeared clear and homogeneous.
The now homogeneous solution in the flask was maintained at 95°C
(203°F)
under reflux and mixing for a period of days. Periodically, samples of the
homogeneous
solution were taken and tests for viscosity, color, and water content were
performed on
the samples. Table 4 below provides the results of the testing.
Table 4
Elapsed Time Number Water Viscosity
At 95°C of Content
(davs) Phases (%) (centipoise)
0 10.0' 530
3 1 530
72 1
13 1
21 1 800
23 1
29 1 8.3 800
Calculated based on initial water charge.
This sample showed the presence of a minor amount of sediment, but
otherwise the sample was a single phase. The amount of sediment was not
considered significant and therefore the source of the sediment was not
determined.
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In performing the method of Example 1, it was also observed that water can be
added to the stable aqueous solution in order to adjust the viscosity while
still
maintaining a single phase system. To a sample of the solution of example 1
that had
been maintained for 29 days, water was added to adjust the viscosity to 540
centipoise
and the water content to 9.2%. The change in water content over time, under
the storage
conditions described above, is believed to be due to normal losses due to
inefficiencies
in the reflux process.
Programmed Addition of Water - Example 2
It has been determined that water may be metered into molten bisphenolic
stillbottoms, in a programmed manner, to make the stable aqueous solutions of
the
present invention. In this example water in an amount equal to 10% of the
combined
weight of water and bisphenolic stillbottom was added to molten V-390. In this
example, a flask fitted with a means for mixing and a means for determining
temperature was used. An atmosphere of air was maintained in the flask.
Initially, V-
390 was charged to a flask and brought to a temperature of 115°C
(239°F) and allowed
to melt under mixing. Although not considered critical to the methods of the
present
invention, the V-390 was allowed to mix for about 15 minutes. Water was then
added
in the amount described above over a 38 minute period under reflux. At the end
of the
38 minute period the temperature of the flask contents at decreased to about
100°C
(212°F). At the end of 38 minute period of water addition, the flask
contents were
mixed for an additional 47 minutes at 100°C (212°F). It was
observed that by using the
above-described programmed addition no cold gelling of the V-390 occurred upon
addition of the water and there was no flooding of the reflux condenser.
Inefficiencies
in the operation of the condenser can explain loss of water during the mixing
of water
and bisphenolic stillbottoms at reflux temperatures.
The advantage of this approach is the ease of transfer, addition and
dissolution
during resin manufacture.
Phenolic Resins Containing Bisphenolic Stillbottoms
In yet another embodiment of the invention, improvements are made in phenolic
resins. Bisphenolic stillbottoms may be used to produce phenolic resins useful
in the
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making of laminates and resin impregnated papers. Like the bisphenolic
stillbottoms,
the stable aqueous solutions of the present invention may also be used in the
synthesis
of resoles and novolacs. Conventional resole and novolac preparation is
further
described below and in Phenolic Resins, Chemistry. Applications and
Performance, (A.
Knop and L.A. Pilato, Springer-Verlag (1985)).
Resole Synthesis
The formation of a resole occurs under generally known conditions. The
reaction is carried out at a molar ratio of phenolic compound to aldehyde of
1:0.2 to
about 1:5. Catalysts typically employed include sodium hydroxide, sodium
carbonate,
alkaline earth oxides and hydroxides, ammonia, hexamethylenetetramine ("HMTA")
and tertiary amines. Resoles may also form under neutral to mildly acidic
conditions.
Divalent metal salts, for example. will catalyze resole formation.
The phenolic compound used in the resole synthesis is preferably phenol itself
but may be cresol, xylenols, alkyl substituted phenols, bisphenol A, bisphenol
F. The
aldehyde used in the resole synthesis is preferably formaldehyde but may be
another
aldehyde such as acetaldehyde, propionaldehyde, n-butyraldehyde,
isobutyraldehyde,
benzaldehyde, glyoxal, and furfural.
The stable aqueous solution of the present invention may also be used in the
synthesis of resole derivatives. For example, the stable aqueous solution may
be used in
the synthesis of an alkoxy-modified-resole. United States patent no.
4,634,758, herein
incorporated by reference in its entirety, discloses a process for
manufacturing alkoxy-
modified resoles. As another example, the stable aqueous solution of the
present
invention may be used in the synthesis of a resole modified with an aliphatic
polyhydroxy compound. The aliphatic polyhydroxy compound is covalently bound
into
the resole. United States patent no. 5,189,079, herein incorporated by
reference in its
entirety, discloses a process for making resoles covalently bound with
polyhydric
alcohols.
A typical process for resole synthesis is described as follows. Reactants are
introduced into a 1 liter four-necked round-bottom flask. The flask is fitted
with means
to stir the flask contents, means to monitor the temperature of the flask
contents, and
means to reflux volatile components and products. Reflux is afforded by use of
a reflux
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condenser fitted to one opening of the four-neck flask. The condenser is
typically
cooled using water. Reactants are pre-weighed before addition to the four-
necked flask.
The stable aqueous solution of the present invention may be added at any point
during
the synthesis. It is well known in the art that the weights of reactants are
adjusted at the
time of addition to account for differences between the nominal assay and the
precise
assay of the reactant. The flask contents are heated by an electric heating
mantle that is
controlled by a rheostat, or by use of a steam table, so that specific
temperatures may be
reached and maintained. Other arrangements will be known to those skilled in
the art.
Similar to the laboratory process described above, larger-scale batches of
resoles, of course, may also be made. Conceptually, the two processes are the
same. In
making the larger plant-scale batches, a reactor vessel is used that possesses
similar
process control capability as the laboratory reaction flask. Therefore, the
reactor vessel
provides means for mixing reactants, means for measuring and controlling the
temperature of the reactants, means for refluxing any volatile compounds in
the reactor
vessel, and means for distilling off the volatile compounds.
The process for making resoles described above presents the basic aspects of
such a process. It is understood by those of skill in the art that
modifications to such a
process may be made and at that various additives, in addition to the basic
components
described above, may be used. For the examples provided below, formaldehyde is
added in what is termed in the art as a programmed addition. In such an
addition,
formaldehyde is metered into a flask or reactor vessel over a period of time
so that a
maximum temperature is not exceeded. Those of skill in the art will recognize,
however, that whether the formaldehyde is added in a single charge or is added
in a
programmed addition will not affect the final resin product.
It has also been discovered that, surprisingly, water tolerance is one means
to
determine when the bisphenolic stillbottoms are to be added to a partially
reacted resole,
in order to produce resins that exhibit a preferred paper saturation at an
appropriately
low free phenol content, as discussed above. If the bisphenolic stillbottom is
added at a
high water tolerance, the resulting resole has a very slow cure speed. If the
bisphenolic
stillbottom is added at a low water tolerance, the resulting aqueous resole
will not
penetrate the paper.
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Novolac Synthesis
Novolac resins are obtained by the reaction of a phenol and an aldehyde in a
strongly acidic pH region. Suitable acid catalysts include the strong mineral
acids such
as sulfuric acid, phosphoric acid and hydrochloric acid as well as organic
acid catalysts
such as oxalic acid, para toluenesulfonic acid, and inorganic salts such as
zinc acetate, or
zinc borate. The phenol is preferably phenol itself but a portion of the
phenol can be
substituted with cresol, xylenols, alkyl substituted phenols such as
ethylphenol,
propylphenol, and mixtures thereof. The aldehyde is preferably formaldehyde
but other
aldehydes such as acetaldehyde, benzaldehyde, and furfural can also be used to
partially
or totally replace the formaldehyde.
The reaction of the aldehyde and phenol is carried out at a molar ratio of 1
mole
of the phenol to about 0.40 to 0.85 mole of the aldehyde. For practical
purposes,
phenolic novolacs do not harden upon heating but remain soluble and fusible
unless a
hardener (curing agent) is present.
Water Tolerance Measurements
The water tolerance test determines the compatibility of the partially reacted
resole with water. In this test, the amount of water which may be added to the
partially
reacted resole while still maintaining a homogeneous solution is determined.
The
results of the test are expressed in terms of a percentage of the weight of
resole equal to
the amount of water added.
The water tolerance test employs distilled or de-ionized water, a laboratory
balance. reading to .O1 gram. test tubes, a constant temperature bath set to
25°C, and
other standard laboratory equipment that will be known to those of skill in
the art. The
distilled or de-ionized water is brought to 25.0 ~ 0.1 °C.
Approximately 10 - 3 grams of
a resin sample is weighed into a test tube and the weight recorded. Next 10 -
3 grams of
water is added to the test tube. The test tube is then capped and shaken to
insure that
sample is thoroughly mixed with water. If the test tube exhibits a cloud, the
test is
restarted and a lesser amount of water than first used is added to the test
tube. Next the
test tube is placed in the 25°C water bath and the sample is agitated.
Additional water is
incrementally added until the cloud point of the sample is reached. The cloud
point end
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point occurs when small white alphanumeric characters on a black background
behind
the sample can no longer be read when looking through the sample. The final
total
weight of the water added to the test tube is determined and recorded. The
water
tolerance of the sample is then calculated as the amount of water added to the
sample
divided by the initial sample weight.
Free Phenol Determination
The unreacted phenol content in phenolic resins may be determined using any of
the well known gas chromatographic methods. In the method used in the examples
below, a gas chromatograph equipped with an FID detector and a 6' x 1/8"
column with
1.2% Atpet-80 and 6.8% di-n-decylphthalate on 60/80 Anachrom ABS is used. The
column oven temperature is maintained at about 130°C, the injection
port temperature at
about 220°C, and the detector temperature at about 220°C. Those
of ordinary skill in
the art will recognize variations of these components and parameters that may
be used.
Resin samples are dissolved in a suitable solvent and spiked with p-cresol as
a standard.
After mixing, the solution of resin, solvent and standard are injected into
the gas
chromatograph and the areas under the phenol and p-cresol peaks are
integrated. The
concentration of the free phenol may then be calculated.
Refractive Index Determination
The refractive index of resin samples was determined using the well-known
Abbe refractometer. Measurements were made at 25°C, with the prisms
of the
refractometer maintained at this temperature by a circulating constant
temperature bath.
Resole Viscosity Determination
Resole viscosity was determined using the well-known Brookfield viscometer.
The Brookfield viscometer measures the viscous resistance to a rotating
spindle
immersed in a fluid. The torque necessary to rotate the spindle in the fluid
is expressed
in centipoise. For the results provided below, a Brookfield Digital Viscometer
Model
DV-II+ was used. Viscosities were determined at a temperature of 25°C
and the
Brookfield Viscometer was maintained at about this temperature using a
circulating
constant temperature bath.
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Gel Time Determination
The gel time of a liquid resin is the length of time, typically expressed in
minutes, required for a resin to become infusible at a given standard
temperature. For
this test, a Sunshine Gel Time Meter, catalog number 22, available from
Sunshine
Scientific Instrument Inc., Philadelphia, Pennsylvania, is used to measure the
end point
of the gel time. In this method, a constant boiling temperature solvent is
used. For gel
time measurements reported below, tetrachloroethylene (perchloroethylene) was
used,
which has a constant boiling temperature of 121 °C. Accordingly, the
gel times reported
below were determined at 121°C. The Sunshine Gel Time Meter will
automatically
identify the end point of the gel time.
Resole Synthesis - Example 3
To a flask, as described earlier, 100 parts of phenol, 3.5 parts of 50%
aqueous
SO% sodium hydroxide, 1 part of sodium sulfite, and 14.9 parts of V-390 were
added.
These components were heated to about 65C, under mixing and atmospheric
pressure.
Next, 111 parts of aqueous 50% formaldehyde solution was metered into the
flask over
a 50 minute period. The temperature of these component reactants was held at
about
70C and allowed to react under mixing for about 120 minutes. The volatile
contents of
the flask were then distilled off under vacuum of about 22 inches Hg until a
distillate
weight of 21.65 Parts was attained. The contents of the flask were then held
at 65C until
a free phenol of about 6.0% was attained. The contents of the flask were
cooled to 25C
and 2.5 parts of acetic acid was added. The pH was then adjusted to 6.56 with
a small
amount of 50% sodium hydroxide.
The resin thus prepared had a refractive index of 1.5409, a free phenol
content of
5.6%, and a viscosity of 433 cps.
Resole Synthesis Using Bisphenolic Stillbottoms - Example 4
To a flask, as described above, 100 parts of phenol, 3.5 parts of a 50%
aqueous
solution of sodium hydroxide, 1 part of sodium sulfite, and 14.9 parts of V-
390 were
added. These components were heated to about 65°C, under mixing and
atmospheric
pressure. Next, 111 parts of a 50% aqueous formaldehyde solution was metered
into the
flask over a 50 minute period. The temperature of these component reactants
were held
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at about 70°C and allowed to react under mixing and reflux for about
120 minutes. The
volatile contents of the flask were then distilled off under a vacuum of about
22 inches
Hg to a distillate weight of 32.1 parts A residual free formaldehyde content
of about 1%
was attained. The contents of the flask was cooled to about 25°C and
2.75 parts of
acetic acid and 6 parts of water was added.
The resin thus prepared had a refractive index of 1.5405, a free phenol
content of
7.8%, and a viscosity of 211 centipoise. The gel time of this resin, at
121°C, was 22.9
minutes.
Resole Synthesis - Example 5
To a reactor vessel, 100 parts of phenol, 1 part of sodium sulfite, 3.~ parts
of a
SO% aqueous solution of sodium hydroxide were added. These components were
heated
to about 65C under mixing and atmospheric pressure. Next, 111 parts of a 50%
aqueous
formaldehyde solution was metered into the vessel over a 50 minute period. The
temperature of these component reactants was held at about 70C for 120
minutes. The
volatile contents of the vessel were then distilled off under vacuum of 23.8
inches Hg
until a distillate weight of 21.5 parts was attained. The contents of the
vessel were then
held at 65C until a water tolerance of 577% was attained. The contents of the
vessel
were cooled to SSC and 14.9 parts of V-390 was added. The temperature was held
at
55C for 45 minutes after the addition was completed. The contents of the
vessel were
cooled to about 45C and 2.75 parts of acetic acid was added. The pH was then
adjusted
to 6.86 with acetic acid and the viscosity to 270 cups with water.
The resin thus prepared had a refractive index of 1.5410, a free phenol
content of
5.3%, and a viscosity of 270 cups.
Resole Synthesis Using Storage Stable Aqueous Solution - Example 6
A resole resin was prepared according to the methods of the present invention
using the storage stable solution of example 2. It was discovered that when
the storage
stable solution was used, no significant difference in resin properties were
obtained
when compared to a resin prepared using neat bisphenolic stillbottoms.
To a flask, as described above, 100 parts of phenol, 3.5 parts of a 50%
aqueous
solution of sodium hydroxide. and 1 part of sodium sulfite were combined, and
110
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parts of a 50% aqueous formaldehyde solution, was then added over a 50 minute
period.
The contents of the flask (the "reactants") were heated to about 70°C,
under mixing and
atmospheric pressure. The temperature of the reactants were held at about
70°C and
allowed to react under mixing and reflux for about 90 minutes. The volatile
contents of
the flask were then distilled off under a vacuum of about 25 inches Hg until a
distillate
weight of 25.65 parts was attained. The flask contents were then allowed to
react under
atmospheric pressure at 66°C until a water tolerance of 1030% was
obtained. At this
point in the reaction the flask contents were cooled to about 60°C.
Next, 16.55 parts of
the storage stable solution of example 2 was added to the flask. The contents
of the
flask were then allowed to continue to mix and react for about 10 minutes at a
temperature of about 60°C. At the end of the 90 minutes reaction time,
the contents of
the flask were rapidly cooled to about 25°C, at which point 3 parts of
acetic acid was
added.
The resin thus prepared had a refractive index of 1.5402, a free phenol
content of
6.0%, and a viscosity of 209 centipoise. The gel time of this resin was 22.15
minutes at
121°C.
Resole Synthesis Using Bisphenolic Stillbottoms - Example 7
To a reactor vessel, as described above, 100 parts of phenol, and 3 parts of a
50% aqueous solution of sodium hydroxide were combined and 115 parts of a 50%
aqueous formaldehyde solution was then added over a 50 minute period. The
contents
of the reactor vessel (the "reactants") were heated to about 75°C,
under mixing and a
vacuum of about 20 inches of Hg, until reflux initiated. The reactants were
allowed to
react at 75°C under reflux for about 1.5 hours. At the end of this 1.5
hour period, the
volatile components of the flask were distilled off at a temperature of about
60°C and a
vacuum of about 20 inches of Hg, to a distilled weight of about 22.4 parts.
The
reactants were then held under atmospheric pressure and 65°C until a
water tolerance of
551% was obtained. At this point in the reaction, 8.5 parts of methanol, 15
parts of V-
390, and 2.7 parts of urea were added to the flask. The temperature of the
reactor vessel
contents was reduced to about 40°C and 1.8 parts of acetic acid were
added to the
reactor vessel.
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The resin thus prepared was determined to have a refractive index of 1.5373, a
viscosity of 191 centipoise, and a free phenol content of 5.3%. The gel time
of the resin
was 19.1 minutes at 121 °C.
S Use of a Bisphenolic Stillbottom Compared to Use of Bisphenol A
The effect of the use of a bisphenolic stillbottom to the synthesis reactants
of a
resole resin on the paper penetration times was further studied. This result
was
compared to the paper penetration properties of a resin prepared using
bisphenol A. In
these examples, either bisphenolic stillbottom or bisphenol A, as noted, were
added with
the initial charge of phenol and formaldehyde in the preparation of the resole
resin.
Resole Synthesis Usine Bisphenol A - Example 8
To a flask, as described above, 100 parts of phenol, 3.5 parts of a 50%
aqueous
solution of sodium hydroxide, 1.0 parts of sodium sulfite and 10 parts of
Bisphenol-A
were added. These components were heated to about 65°C, under mixing
and
atmospheric pressure. Next, 111.0 parts of a 50% aqueous formaldehyde solution
was
metered into the flask over a 50 minute period at 70°C. The temperature
of these
component reactants were held at about 70°C and allowed to react under
mixing and
reflux for about 2 hours. The volatile contents of the flask were then
distilled off under
a vacuum of about 25 inches Hg until a distillate weight of 31.9 parts and a
residual free
formaldehyde content of about 1 % was attained. The contents of the flask was
cooled to
about 25°C and 2.75 parts of acetic acid was added.
The resin thus prepared had a refractive index of 1.5400, a free phenol
content of
8.3%, and a viscosity of 175 centipoise.
Resole Synthesis Using Bisphenolic Stillbottoms - Example 9
The present example demonstrates the manufacture of the resins of the present
invention on a large, commercial, scale. To a reactor vessel, as described
above, 5,963.0
pounds of phenol, and 179.0 pounds of a 50% aqueous solution of sodium
hydroxide
were combined and 6,858.0 pounds of a 50% aqueous formaldehyde solution was
then
added over a 50 minute period. The contents of the reactor vessel (the
"reactants") were
heated to about 75°C, under mixing and a vacuum of about 20 inches of
Hg, until reflux
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initiated. The reactants were allowed to react under reflux for about 2 hours.
The
temperature of the reactants were held at about 75°C aver this 2 hour
period. At the end
of this 2 hour period, the volatile components of the flask were distilled off
at a
temperature of about 60°C and a vacuum of about 24 inches of Hg to a
distillate weight
of 1410 pounds. The reactants were then held at 70°C under reflux and
about 22 inches
of Hg until a water tolerance of 393% was obtained. At this point in the
reaction the
reactor vessel contents were cooled to about 55°C and the vacuum was
maintained at
about 25 inches of Hg. Next, 1151.0 pounds of V-390 was added to the reactor
vessel
and allowed to mix and react for about 1 hour. Next, 161.0 pounds of urea were
added
to the reactor vessel. The temperature of the reactor vessel contents was
about 60°C, the
vacuum was about 23 inches of Hg, and the reaction was continued for about 1
additional hour. At the end of this 1 hour reaction period 103 pounds of
acetic acid
were added to the reactor vessel. An additional 130 pounds of water and 12
pounds of
acetic acid was added to the contents of the reactor vessel, thereby adjusting
the
refractive index, viscosity, and pH.
The resin thus prepared was determined to have a refractive index of 1.5435, a
viscosity of 271 centipoise, and a free phenol content of 5.0%. The gel time
of the resin
was 18.1 minutes at 121 °C.
Measuring Resin Penetration of Paper
The utility of the resins of the present invention may be determined, in part,
based on the ability of the resin to penetrate paper. One parameter useful in
assessing
this ability is the amount time it takes the resin to penetrate paper in a
standardized test.
The penetration times reported below were determined using a standardized
paper penetration test. This test indicates the capability of the resin being
tested to
penetrate and completely wet the fibers in a paper sheet. The equipment used
in the test
includes: a pan capable of holding 0.5 to 1.0 inch of the resin and having a
minimum
diameter of 3.5 inches; a thermometer capable of reading 25.0 + 0.1°C;
and a stopwatch.
The paper used in this test is a Westvaco 115 pound basis weight paper. The
paper is
cut in the shape of a 2 3~4 inch diameter circle. Prior to testing the paper
is to be stored in
a dessicator containing CaClz ~ 6H20 to maintain 31 % R.H. (relative humidity)
at
24.5°C.
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To begin the test, the resin is brought to a temperature of 25°C. The
paper disc
is placed in the pan of resin with the "shiny" side of the paper facing the
liquid resin
while simultaneously starting the stopwatch. The wetting of fibers is observed
as the
resin penetration progresses. The time when the exposed surface area of the
paper disc
is initially wet through marks the end of the test. It is this time that is
reported as the
penetration time.
Paper Penetration Results Using Resins of Examples 3 - 9
The following Table 5 summarizes the results of paper saturation tests
performed
using the resole resins of the examples. As demonstrated, paper penetration is
dependent on the water tolerance the resin had attained at the time of
addition of a
bisphenolic compound.
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Table 5
Example Number Cure Time Water Tolerance Free Phenol Initial
At 121°C At Time of Addition Content Penetration
Time
(minutes) (%) (%) (seconds)
3 17.6 infinite 5.6 > 180
4 22.9 infinite 7.8 18
5 20.0 577 5.3 42
6' 22.15 1030 6.0 30
72 19.1 551 5.3 21
8 22.2 infinite 8.3 15
9 19.2 393 5.0 70
The resole of example 6 was made using the storage stable solution of the
present invention.
2' The resole of example 7 was made using methanol as the solvent. All
others are water based products.
As demonstrated by the data of Table 5, the stable solution of the present
invention provides for the manufacture of a resin that allows excellent paper
penetration
without adversely affecting gel or free phenol content. Furthermore, use of
the stable
aqueous bisphenolic solution of the present invention allows the manufacture
of resin
without the addition of methanol, yet exhibiting excellent paper penetration.
As seen by
the results of table 3, the paper penetration time is very dependent upon when
the
stillbottoms are added during the resin manufacture.
Further examples of resole synthesis using an alternate source of bisphenolic
stillbottom are presented below.
Resole Synthesis Using Bisphenolic Stillbottoms - Example 10
To a flask, as described above, 100 parts of phenol and 2.93 parts of a 50%
aqueous solution of sodium hydroxide were added and brought to 55°C.
Next, 112.6
parts of a 50% aqueous formaldehyde solution was metered into the flask over a
50
minute period. The temperature of these component reactants were held at about
75°C
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and allowed to react under mixing and reflux for about 120 minutes. The
volatile
contents of the flask were then distilled off under a vacuum to a distillate
weight of 36
parts at 60-62°C. The contents of the flask was heated to about
72°C, with the water
tolerance dropping to about 580%. The contents of the flask were then further
cooled to
about 60°C and 10 parts of BPA HEAVIES was added under mixing. The
contents of
the flask was maintained at about 60°C, under mixing, for an additional
one hour period.
During this one hour hold, 10 parts of water was added to adjust the solids
content.
Next, 2.65 parts of urea was added and the flask contents were cooled to
40°C. Next,
the flask contents were cooled to 25°C and 1.76 parts of acetic acid
was added.
The resin thus prepared had a refractive index of 1.5390, a free phenol
content of
5.8%, and a viscosity of 179 centipoise. The resin thus prepared exhibited a
gel time of
19.5 minutes at 121°C.
Resole Synthesis Using Storage Stable Solution - Example 11
To a flask, as described above, 100 parts of phenol and 2.92 parts of a 50%
aqueous solution of sodium hydroxide were added and brought to 55°C.
Next, 111.9
parts of a 50% aqueous formaldehyde solution was metered into the flask over a
50
minute period. The temperature of these component reactants were held at about
75°C
and allowed to react under mixing and reflux for about 120 minutes. The
volatile
contents of the flask were then distilled off under a vacuum to a distillate
weight of 26.9
parts at 60°C. The contents of the flask were heated to about
70°C, allowing the water
tolerance to drop to about 580%. The contents of the flask were then further
cooled to
about 60°C and 11.0 parts of a storage stable solution of the present
invention,
consisting of 90% BPA HEAVIES in aqueous solution, was added under mixing. The
contents of the flask were maintained at about 55°C, under mixing, for
an additional one
hour period. Next, 2.63 parts of urea was added and the flask contents were
cooled to
40°C. Next, the flask contents were cooled to 25°C and 1.69
parts of acetic acid was
added.
The resin thus prepared had a refractive index of 1.5396, a free phenol
content of
6.4%, and a viscosity of 197 centipoise. The resin thus prepared exhibited a
gel time of
18.5 minutes at 121 °C.
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Example 12, presented below, illustrates novolac synthesis using a bisphenolic
stillbottom.
Novolac Stillbottoms Modified -- Example 12
It has also been learned that the stillbottoms modification is not to be
limited in
use to that of resole resins. A stillbottoms modified novolac resin has been
produced in
the following manner:
To a reactor vessel, 100 parts of phenol and 1 1. l parts of V-390 were added.
The contents of the vessel were heated to 62-68C under agitation wherein the V-
390
easily dissolved. At this temperature, 0.36 parts of oxalic acid was added.
Other acids
may be used (sulfuric, etc) and are known by those practiced in the art. The
contents
(''reactants") of the vessel were further heated to 98-100C. Next, 43.9 parts
of 50%
formaldehyde solution was metered into the vessel over a 60 minute period. The
temperature of these component reactants were held at 100C for 3 hours until
the free
formaldehyde content of the water portion was less than 0.5%. The contents of
the
vessel were then distilled atmospherically to 170C. Next, vacuum distillation
was
initiated and continued until the desired free phenol content was obtained. In
this
example, it was 1.56%. The resulting product made a novolac of an orange
color, tack-
free, clear appearance, and having a viscosity of 4880 cps (cone & plate 100
cone;
125C). A novolac, thus prepared, is expected to have applications in Abrasives
and
Friction Industries where higher temperature resistance and less brittleness
would
contribute to the product maintaining its integrity.
A comparison of the results of Examples 4 and 8 demonstrates that the use of a
bisphenolic stillbottom in the synthesis of a resole resin can result
advantageously in a
product that has a comparable initial penetration time when compared to a
similar resin
made using bisphenol A instead of the bisphenolic stillbottom. This also
demonstrates a
low cost alternative to the use of the alkylidenepolyphenol, bisphenol A.
The results provided in Table 4 also demonstrate the effect of adding the
bisphenolic stillbottom at an effectively infinite water tolerance. The water
tolerance at
the time of addition of the bisphenolic stillbottom is high, because the
principle
reactants, phenol and formaldehyde, are in aqueous solution and resin solids
have not
yet been produced.
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The data disclosed herein demonstrates a preferred range of water tolerance at
which a bisphenolic stillbottom is added to a reacting resole resin of about
400% to
about 1100%. Although it is clear from the examples that the bisphenolic
stillbottoms
may be added at a water tolerance in excess of 1100%, it is preferred that the
residual
free phenol be less than the nominally 8% demonstrated in Examples 5, 6 and 9.
By
comparison, Example 6, employing a storage stable solution of the present
invention
added at a water tolerance of 1030%, yielded a free phenol concentration of
6%.
Accordingly, the preferred upper limit of water tolerance at which a
bisphenolic
stillbottom is added to the reacting resole resin is about 1100%. Reference to
Table 5
(example 9) demonstrates that when a bisphenolic stillbottom is added to a
reacting
resole resin at water tolerance of about 393%, the initial penetration time of
the resulting
resin is slow. However, when the bisphenolic stillbottom is added at a water
tolerance
of about 600 - 1000%, the initial penetration time is greatly reduced.
Therefore, the
preferred lower limit of water tolerance at which a bisphenolic stillbottom is
added to
the reacting resole is about 400%, as shown by examples 5 and 9.
Applications of the Compositions of the Present Invention
The resins of the present invention are useful in, but not limited to, a broad
range
of laminating and paper preparation processes. For example, the resins of the
present
invention may be used in conventional laminating processes, such as used for
the
manufacture of kitchen countertops. The resins of the present invention may
also be
used in the preparation of decorative laminates. In the laminating process, as
will be
understood by those of ordinary skill in the art, laminate layers are bonded
together
using a resin. The resins of the present invention are thus useful in bonding
together the
laminate layers. The resins of the present invention may be used in the
preparation of
saturated, or partially saturated, paper products, such as filter paper. The
compositions
of the present invention may also be used in paper coatings, or saturating,
fiberglass
bindings, abrasions, friction composites, particle board, and refractories.
Generally, the
composition of the present invention may be used where lower emissions and/or
plasticity are sought.
Each application of the resins of the present invention may require further
modification of the resoles. For example, certain laminating processes, or
processes
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used in the preparation of filter paper, may require the addition of an
alcohol, such as
methanol or ethanol, to the resole, to further facilitate paper penetration.
However, it
should be understood, that use of the stable aqueous solution of the present
invention
can eliminate the use of such an alcohol for some applications by virtue of
the time at
which it is added.
The effective amount of the resins of the present invention used in the
applications in which such resins may be used will vary from application to
application.
However, such amounts will be readily understood by those of ordinary skill in
the art.
Furthermore, the methods of making laminates and paper products, as referred
to herein,
will also be readily understood by those of ordinary skill in the art.
Embodiments of the present invention also provide laminates made using
phenolic resins which exhibit excellent finished product properties. Such
paper
laminates can exhibit reduced emissions during treating when compared to
laminates of
the prior art because, among other reasons, the elimination of alcohol from
the resin
formulation and a low free phenol concentration in the resole. Furthermore,
improved
laminates having excellent flexibility may be made according to embodiments of
the
present invention.
Thus it has been disclosed in embodiments and the preferred embodiment of the
present invention, a storage stable solution of bisphenolic stillbottoms and
solvents
including water and other solvents. A method of making such stable solutions
is
likewise disclosed. It has also been disclosed in embodiments of the present
invention
resins made using such storage stable solutions. Such resins exhibit a low
free phenol
content and allow the production of laminates with desirable physical
properties related
to resin penetration of the paper. Improved laminates having excellent
flexibility have
also been disclosed in embodiments of the present invention. The present
invention also
provides a method by which paper penetration may be controlled as a function
of the
water tolerance and the time at which the stillbottoms are added. Other
embodiments
can be easily envisioned within the basic principles of the present invention.
It should be understood that various changes and modifications preferred in
the
embodiment described herein will be apparent to those skilled in the art. Such
changes
and modifications can be made without departing from the spirit and scope of
the
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present invention and without demising the attendant advantages. It is,
therefore,
intended that such changes and modifications be covered by the appended
claims.
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