BENZYLIC ETHER PHENOLIC RESOLE RESINS, THEIR PREPARATION, AND USES

RESINES RESOLS PHENOLIQUES D'ETHER BENZYLIQUE, ET PREPARATION ET UTILISATION DE CES RESINES

English Abstract

This invention relates to benzylic ether phenolic resole resins and the
process for preparing them. The benzylic ether phenolic resole
resins are prepared by heating phenol and an aldehyde in a sealed reaction
vessel in the presence of a divalent metal catalyst without
removing water generated by the reaction until an appropriate endpoint for the
resin is reached. The benzylic ether phenolic resole resins
produced by the process are preferably free or essentially free of unreacted
formaldehyde and can be used in the resin component of
phenolic-urethane foundry binders to make foundry cores and/or molds by the
cold-box and no-bake processes. The cores and/or molds are
used for making metal castings.

French Abstract

L'invention concerne des résines résols phénoliques d'éther benzylique, et un procédé pour préparer ces résines. Les résines résols phénoliques d'éther benzylique sont préparées en chauffant le phénol et un aldéhyde dans une cuve de réaction fermée hermétiquement en présence d'un catalyseur de métal divalent sans retirer l'eau générée par la réaction jusqu'à obtenir un point limite approprié pour la résine. Les résines résols phénoliques d'éther benzyliques produites par ce procédé sont, de préférence, dépourvues ou sensiblement dépourvues de formaldéhyde n'ayant pas réagi et peuvent être utilisées dans le composant résine des liants d'uréthane phénoliques pour fonderie, pour fabriquer des noyaux et/ou des moulages de fonderie selon des procédés de moulage en boîte froide et de durcissement à froid. Les noyaux et/ou les moulages sont utilisés pour fabriquer des produits moulés métalliques.

Claims

CLAIMS
We claim:
1. A process for preparing a benzylic ether phenolic resole resin where
said resin comprises (1) at least one component having a sungle ring
phenolic structure, and (2) at least one component having a multiple ring
phenolic structure, and wherein said process comprises:
(a) charging a phenol, aldehyde, and a catalytic amount of a divalent
metal catalyst to a sealable reaction vessel capable of maintaining
a pressure above atmospheric pressure, such that the mole ratio of
aldehyde to phenol ratio is from 1.0:1.0 to 1.5:1.0;
(b) sealing said reaction vessel;
(c) heating said sealed reaction vessel to a temperature in the range of
100°C to 150°C sufficient to generate a pressure of at least 10
psig
above normal atmospheric pressure within the seated reaction
vessel;
(d) continuing said reaction, without removing water formed by the
reaction, until an appropriate endpoint is reached;
(e) venting the reactor to 0 psig while distilling excess water and
other condensable vapors; and
(f) applying a vacuum to distill the remaining condensable vapors.
28

2. The process of claim 1 wherein the free formaldehyde of said resin is less
than 0.25%.
3. The process of claim 2 wherein the phenol is selected from the group
consisting of phenol, o-cresol, p-cresol, and mixtures thereof.
4. The process of claim 3 wherein the aldehyde is formaldehyde.
5. The process of claim 4 wherein an alcohol is added to the charge.
6. The process of claim 4 or 5 wherein an aldehyde is reacted with a phenol
such that the molar ratio of aldehyde to phenol is from 1.0:1.0 to 1.2:1.0 in
the presence of a divalent metal catalyst.
7. The process of claim 6 wherein the temperature of the reaction vessel is
heated to 125° C to 135°C and the pressure within the reaction
vessel is
between 20 psig and 40 psig.
8. The process of claim 7 wherein the reaction vessel is equipped with a
stirring means, cooling means, heat sensor, and pressure sensor.
9. The process of claim 8 wherein the yield of benzylic ether phenolic
resole resin is from 80 to 90 weight percent.
10. A benzylic ether phenoiic resole resin, prepared by the process of claim
1, whereby said resin comprises:
(a) at least one component having a single ring phenolic structure,
and
(b) at least one component having a multiple ring phenofic structure,
29

where the resin is characterized by the following:
(1) a benzylic ether to methylene bridge ratio, as determined by C13
NMR spectroscopy of from 0.3:1.0 to 0.9:1.0;
(2) a total ortho to para substitution ratio of 3:1.0 to 10:1.0;
(3) an weight average molecular weight (M w), as determined by gel
permeation chromatography, of 700 to 2,000; and
(4) a viscosity of 0.7 centipoise to 5.0 centipoise at 100 °C.
11. The resin of claim 10 which contains less than 0.25% free formaldehyde.
12. The resin of claim 11 wherein the weight ratio of (a) to (b) is from 5:100
to 67:100.
13. The resin of claim 12 characterized by:
(1) a benzylic ether to methylene bridge ratio, as determined by C13
NMR spectroscopy of from 0.4:1.0 to 0.85:1.0;
(2) a total ortho to para substitution ratio of 3:1.0 to 10:1.0;
(3) a weight average molecular weight (M w), as determined by gel
permeation chromatography, of 900 to 1,400; and
(4) a viscosity of 0.7 centipoise to 2.0 centipoise at 100°C.

14. A benzylic ether phenolic resole resin, prepared in a sealed reaction
vessel wherein said reaction vessel is heated to generate an internal pressure
in said reaction vessel, which comprises a mixture of components (I) and (Il)
represented by the following structural formulae:
<IMG>
where
A = -H , -CH2OH, -CH2OR or a C1 to C20 hydrocarbon radical;
X = -OH, -OR, or <IMG>
(III)
31

Y = H, -CH2OH, or -CH2OR;
Z= -H, -R, or <IMG>
(IV)
R = a C1 to C20 hydrocarbon radical;
m, n and p = 0,1 or greater than 1;
w = 1 or greater than 1;
the sum of w and p is at least 2, and
such that the benzylic ether to methylene bridge ratio for the mixture of (1)
and
(II), as determined by C13 NMR spectroscopy, is from 0.3:1.0 to 0.9:1Ø
15. The resin of claim 14 which contains less than 0.25% free
formaldehyde.
32

16. The resin of claim 15 characterized by the following:
(1) a benzylic ether to methylene bridge ratio, as determined by C13
NMR spectroscopy of from 0.3: 1.0 to 0.9:1.0;
(2) a total ortho to para substitution ratio of 3:1.0 to 10:1.0;
(3) a weight average molecular weight (M w) of 700 to 2,000; and
(4) a viscosity of 0.5 centipoise to 5.0 centipoise at 100°C.
17. The resin of claim 16 wherein the weight ratio of structure I to structure
II is from 5:100 to 67:100.
18. The resin of claim 17 characterized by the following:
(1) a benzylic ether to methylene bridge ratio, as determined by C13
NMR spectroscopy of from 0.4:1.0 to 0.75:1.0;
(2) a total ortho to para substitution ratio of 3:1.0 to 10:1.0;
(3) a weight average molecular weight (M w) of 900 to 1,400; and
(4) a viscosity of 0.7 centipoise to 2.0 centipoise at 100°C.
19. A polyurethane-forming binder system curable with a catalytic amount of a
tertiary amine catalyst comprising as separate components:
(a) a benzylic ether phenolic resin component which comprises the
resin of claim 14, 15, 16, 17, or 18, and
33

(b) a polyisocyanate component.
20. The binder system of claim 19 wherein the resin component contains a
solvent in which the benzylic ether phenolic resole resin is soluble, and
wherein the polyisocyanate component contains a solvent in which the
polyisocyanate is soluble.
21. The binder system of claim 20 wherein the ratio of hydroxyl groups of the
benzylic ether phenolic resin to the isocyanate groups of the
polyisocyanate hardener is from 0.9:1.1 to 1.1:0.9.
22. A foundry mix comprising:
(a) a major amount of an aggregate; and
(b) the binder system of claim 19, 20, or 21 in the amount of about 0.5
to 10.0 weight percent based upon the weight of the aggregate.
23. The foundry mix of claim 22 which also contains a liquid tertiary amine
curing catalyst.
24. A cold-box process for preparing a foundry shape which
comprises:
(a) forming a foundry shape by introducing the foundry mix of claim 22
into a pattern;
(b) hardening the shaped foundry mix in the pattern to become self-
supporting with a gaseous tertiary amine curing catalyst; and
34

(c) removing the hardened foundry shape of step (b) from the
pattern and allowing it to further cure, thereby obtaining a
hard, solid, cured foundry shape.
25. no-bake process for preparing a foundry shape comprising:
(a) forming the foundry mix of claim 23 by mixing the foundry
aggregate with the polyurethane-forming binder;
(b) introducing the foundry mix of step (a) into a pattern;
(c) hardening the foundry mix in the pattern to become self-
supporting; and
(d) thereafter removing the shaped foundry mix of step (c) from
the pattern and allowing it to further cure, thereby obtaining
a hard, solid, cured foundry shape.
26. A process of casting a metal which comprises:
(a) preparing a foundry shape in accordance with claim 24;
(b) pouring said metal while in the liquid state into around said
shape;
(c) allowing said metal to cool and solidify; and
(d) then separating the molded article.

27. A process of casting a metal which comprises:
(a) preparing a foundry shape in accordance with claim 25;
(b) pouring said metal while in the liquid state into around said
shape;
(c) allowing said metal to cool and solidify; and
(d) then separating the molded article.
36

Description

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
BENZYLIC ETHER PHENOLIC RESOLE RESINS,
THEIR PREPARATION, AND USES
FIELD OF THE INVENTION
This invention relates to benzyiic ether phenolic resole resins and the
process for preparing them. The benzylic ether phenolic resole resins are
prepared by heating phenol and an aldehyde in a sealed reaction vessel in the
presence of a divalent metal catalyst without removing water generated by the
reaction until an appropriate endpoint for the resin is reached. The benzylic
ether phenolic resole resins produced by the process are preferably free or
essentially free of unreacted formaldehyde and can be used in the resin
component of phenofic-urethane foundry binders to make foundry cores and/or
molds by the cold-box and no-bake processes. The cores and/or molds are
used for making metal castings.
BACKGROUND OF THE INVENTION
Two major categories of phenolic resins are known. These are the
novolak resins and the phenolic resole resins. Novolak resins are prepared by
the reaction of excess phenol with formaldehyde under strongly acidic
conditions where the formaldehyde to phenol ratio is typically from 0.5:1.0 to
1.0 :1Ø Novolak resins are linear or slightly branched condensation products
linked together by methylene bridges, and have relatively low molecular
weight, i.e. up to approximately 2,000. They are soluble and permanently
fusible, i.e. thermoplastic. Novolaks are cured with hexamethylenetetramine
(HEXA). In foundry applications, novolak resins are almost exclusively used
in the "shell process" where foundry sand is precoated with the resin before
curing with HEXA.
On the other hand, phenolic resole resins are prepared by the reaction
. of phenol and excess formaldehyde under alkaline conditions. Formaldehyde
to phenol ratios between 1.1:1.0 to 3.0:1.0 are customarily used. Phenolic
resole resins are somewhat stable at room ternperature, but are transformed
into three dimensional, crosslinked, insoluble, and infusible polymers by the
application of heat.
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It is generally accepted that the best overall performance characteristics
for phenolic-urethane foundry binders are achieved by using highly ortho
substituted phenolic resole resins having benzylic ether and methylene
bridging units between the constituent aromatic rings where the ratio of ether
to methylene bridging units is at least 1.0, i.e. benzylic ether phenolic
resole
resins. These benzylic ether phenolic resole resins are produced by the
reaction of phenol with formaldehyde in the presence of a divalent metal
catalyst at atmospheric pressure with reflux such that the formaldehyde to
phenol ratio in the reaction charge is generally from 1.0:1.0 to 2.0:1Ø
The preparation of benzylic ether phenolic resole resins involves the
reaction of phenol and formaldehyde in the presence of a divalent metal
catalyst in an open reaction vessel at increased temperature and the
continuous stripping of water formed by the reaction from the reaction
mixture.
See U.S. Patents 3,409,579; 3,485,797; and 4,546,124.
It is known to use pressure in the preparation of novolak resins. R. W.
Martin in 'The Chemistry of Phenolic resole resins," John Wiley & Sons, 1956,
p. 111 mentions preparation of novolak resins without catalysts at high
temperatures in autoclaves. A. Knop and L. A. Pilato in "Phenofic resole
resins
Chemistry, Applications and Pertormance," Springer-Verlag, 1985, pp. 93-95
mentions the continuous production of novolak resins which involves heating
at 120°C -180°C at up to 100 psig to enhance the reaction rate.
A process for
preparing novolak resins under pressure is disclosed in U.S Patent 3,687,896,
although it is not clear how the pressure in the reaction vessel is obtained.
These novolak resins prepared under pressure are not highly ortho substituted
and contain only methylene bridges between the aromatic rings.
SUMMARY OF INVENTION
This invention relates to a process for preparing a benzylic ether
phenolic resole resin in a sealed reaction vessel comprising:
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(a) charging phenol, an aldehyde, optionally an alcohol, and a
catalytic amount of a divalent metal catalyst to a sealable
reaction vessel capable of maintaining a pressure above
atmospheric pressure, preferably equipped with a stirring means,
'. 5 heating means, cooling means, heat sensor, and pressure
sensor, such that the mole ratio of formaldehyde to phenol in the
reaction charge is from 1.0:1.0 to 1.5:1.0 ;
(b) sealing said reaction vessel;
(c) heating said sealed reaction vessel to a temperature sufficient to
generate a pressure of at least 10 psig, typically 10 psig to 50
psig, above atmospheric~pressure within the sealed reaction
vessel;
(d) continuing said reaction, without removing water formed by the
reaction, until an appropriate endpoint is reached;
(e) venting the reactor to 0 psig while distilling excess water and
other condensable vapors; and
(f) applying a vacuum to distill the remaining condensable vapors.
The process takes place in a sealed reaction vessel which is heated
sufficiently to generate an internal pressure in the reaction vessel. Since
the
reaction vessel remains sealed, the water formed by the reaction of the phenol
and formaldehyde is not removed until the endpoint of the reaction is reached.
The process has several advantages when compared to processes which use
an open reaction vessel for making benzylic ether phenoiic resole resins:
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1. When resins of comparable weight average molecular weight are
prepared, the process results in a higher conversion or yield of raw
materials to benzyiic ether phenolic resole resin per unit of time.
2. The process results in lower yields of unreacted starting materials such
as formaldehyde, phenol, and alcohol.
3. The process results in shorter cycle times.
4. Benzyiic ether phenolic resole resins of the same molecular weight can
be made with lower formaldehyde to phenol ratios.
5. The product which remains after distillation of the water of reaction and
the unreacted starting materials is essentially free of unreacted
formaldehyde, i.e. less than 1 % free formaldehyde, typically less than
0.25 weight %, preferably non detectable or 0% free formaldehyde.
6. The weight average molecular weight and viscosity of the mixture
remaining after distillation is such that the mixture is particularly suitable
for use in foundry binders.
The reaction product, before distillation, made with this process
comprises (1 ) at least one component having a single ring phenolic structure;
(2) at least one component having a multiple ring phenolic structure; (3)
water;
and (4) unreacted raw materials such as formaldehyde, phenol, and other
organic products. Components (3) and (4) are removed from the mixture by
distillation.
For purposes of this invention, the mixture of (1 ) and (2) will be referred
to as "a benzylic ether phenolic resole resin". The "benzylic ether phenolic
resole resin" is the mixture that remains after separation of the water and
unreacted starting materials and comprises (1 ) at least one component having
a single ring phenolic structure (represented by structure I which follows),
and
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(2) at least one component having a multiple ring phenoiic structure
(represented by structure II which follows) which is used for making foundry
binders. Structure II represents dimers, trimers, oligomers, and or polymers.
This mixture may also contain some minor amounts of water and
unreacted starting materials such as phenol, formaldehyde, and alcohol. The
mixture is typically formed such that the weight ratio of (1 ) to (2} is
typically
from 0:100 to 67:100, more typically from 5:100 to 33:100, and is preferably
essentially free of formaldehyde, i.e. less than 1 % free formaldehyde,
typically
less than 0.25% free formaldehyde, preferably 0 % free formaldehyde. The
mixture has a weight average molecular weight (MW) of about 700 to 2,000,
preferably 900 to 1,400, and a viscosity of about 0.5 poise to about 5.0 poise
100°C, preferably 0.7 poise to about 2.0 poise at 100°C when a
formaldehyde
to phenol molar ratio of about 1.0:1.0 to about 1.5.1:0, preferably about
1.0:1.0
to about 1.2:1.0 is used to prepare the resins. Furthermore, the "benzylic
ether
phenolic resole resin" comprising (1 ) at least one component having a single
ring phenolic structure, and (2) at least one component having a multiple ring
phenolic structure has a benzylic ether to methylene bridge ratio, as
determined by C13 NMR spectroscopy of from 0.3:1.0 to 0.9:1.0, preferably
0.4:1.0 to 0.85:1.0; and (b) a total ortho to para substitution ratio of
3.0:1.0 to
10.0:1Ø
The benzylic ether phenolic resole resins, made in a sealed reaction
vessel in the presence of pressure resulting from the reaction, are suitable
for
use in the resin component of a phenoiic urethane foundry binder and can be
used to make acceptable foundry cores and/or molds by the no-bake or cold-
box process. This is surprising in view of the teachings in U.S. Patents
3,409,579; 3,485,797; and 4,546,124 which indicate that it is highly preferred
to use benzylic ether phenolic resole resins which have a benzylic ether to
methylene bridge ratio greater than 1Ø
Furthermore, tests indicate that castings made with cores and/or molds
from these resins made under pressure have less metal penetration. Metal
penetration occurs when metal or metal oxides fill the voids between the sand
grains of the core without displacing them or chemically changing the silica
or
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binder. When there is penetration in a casting, the casting will require
repair
or be discarded as scrap. This increases cost and decreases efficiency in the
foundry.
ENABLING DISCLOSURE AND BEST MODE
The benzylic ether phenolic resole resin is prepared by reacting an excess
of aldehyde with a phenol in the presence of a divalent metal such as zinc,
lead,
manganese, copper, tin, magnesium, cobalt, calcium, or barium in a sealed
reaction vessel heated to a temperature sufficient to generate pressures of 10
psig
to 50 psig, most preferably from 20 psig to 40 psig, within the reaction
vessel. The
reaction vessel is typically equipped with a stirring means, heating means,
cooling means, heat sensor, pressure sensor. The mole ratio of formaldehyde
to phenol in the reaction charge is from 1.0:1.0 to 1.5:1.0, preferably from
1.0:1.0 to 1.2:1Ø
Typically, the temperature of the reactor needed to generate the
appropriate pressures is from of 100° C to 150°C, most
preferably to 120°C to
135°C. For safety reasons, the temperature is preferably increased
incrementally in stages to avoid creating a highly exothermic reaction. Since
the reaction vessel is sealed, the reaction will take place in the presence of
water formed by the reaction of the formaldehyde and phenol. Heating and
pressure are maintained while the reaction continues without removing water
formed by the reaction.
After an appropriate endpoint is reached, any water of reaction is
removed by distillation along with unreacted starting materials such as
formaldehyde, phenol, and alcohol. Examples of appropriate endpoints
include percent free formaldehyde and viscosity. Typical endpoints based on
free formaldehyde vary from 0 to 0.2 using the sodium sulfite test.' When the
appropriate endpoint is reached, the reactor is then vented to 0 psig white
' To measure free formaldehyde by the sodium sulfite test, the resin mixture
is dissolved in an
organic solvent such as tetrahydrofuran and then aqueous sodium sulfite is
added to form a
solution. The solution is titrated with 0.1 N HCI and free formaldehyde is
calculated.
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distilling excess water and other condensable vapors. A vacuum is applied to
distill the remaining condensable vapors.
The product of this process is an aqueous mixture comprising (1 ) at least
one component having a single ring phenolic structure, and (2) at least one
- 5 component having a multiple ring phenolic structure, (3) water, and (4)
unreacted starting materials such as formaldehyde, phenol, and alcohol where
the
weight ratio of (1 ) and (2) to (3) and (4) is from 80:20 to 95:5, typically,
from 82:18
to 90:10. The benzylic ether phenolic resole resin comprises (1) at least one
component having a single ring phenoiic structure, and (2) at least one
component having a multiple ring phenolic structure, and is separated from the
unreacted starting materials and water by distilling the water and unreacted
starting materials, leaving the benzylic ether phenolic resole resin which is
a
mixture of (1 ) and (2). The resulting benzylic ether phenolic resole resin
preferably contains less than 1.0% free formaldehyde, typically less than
0.25% free formaldehyde, preferably non detectable or 0% free formaldehyde,
and is characterized by a benzylic ether to methylene bridge ratio, as
determined by C13 NMR spectroscopy, of from 0.3:1.0 to 0.9:1.0, preferably
0.4:1.0 to 0.80:1.0, and a total ortho to para substitution ratio of 3:1 to
10:1.
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The benzylic ether phenolic resole resin comprises a mixture of
components (I) and (11) represented by the following structural formulae:
OH
A A
A
(I)
OH OH OH
X HZ HZ-O H2 Hy H2-O Z
A
A m ~ A n ~ w
B)
where
A = -H , -CH20H, -CH20R or a C, to Czo hydrocarbon radical;
OH
X = -OH, -OR, or Y
A
( III )
Y = H, -CHzOH, or -CH20R;
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OH
Z = -H, -R, or
a J
P
R = a C, to Czo hydrocarbon radical;
m, n and p = 0,1 or greater than 1;
w = 1 or greater than 1;
the sum of w and p is at least 2, and
such that the benzylic ether to methylene bridge ratio for the mixture of (I)
and
(II), as determined by C13 NMR spectroscopy, is from 0.3:1.0 to 0.9:1.0,
preferably 0.4:1.0 to 0.8:1Ø
In a preferred embodiment of the benzylic ether phenolic resole resin,
the mixture of structures I and II is such that:
1. At least 75 percent by weight of the mixture is attributed to molecules
represented by structure II.
2. The total ortho to para substitution ratio in structure II is from 3.0:1.0
to
1 0.0:1Ø
3. The weight average molecular weight of the mixture is from 900 to
1,400.
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4. The mixture has essentially less than 0.25% free formaldehyde as
determined by the sodium sulfite test.
5. The benzylic ether to methylene bridge ratio, as determined by NMR
spectroscopy is preferably from 0.4:1.0 to 0.85:1.0 for modified benzylic
ether phenolic resole resins, and preferably from 0.4:1.0 to 0.75:1.0 for
unmodified benzylic ether phenolic resole resins.
6. The viscosity is from 0.7 poise to about 2.0 poise at 100°C.
7. The resins are prepared by using a formaldehyde/phenol ratio of from
1.0:1.0 to 1.2:1.0, more particularly 1.0:1.0 to 1.1:1Ø
Generally, the phenols used to prepare the benzylic ether phenolic resole
resins
may be represented by the following structural formula:
OH
B B B
where B is a hydrogen atom, or hydroxyl radicals, or hydrocarbon radicals or
oxyhydrocarbon radicals, or halogen atoms, or combinations of these. Multiple
ring phenols such as bisphenol A may be used.
Specific examples of suitable phenols used to prepare the benzyiic ether
phenolic resole resins include phenol, o-cresol. p-cresol, m-cresol, p-
butylphenol,
p-amylphenol, p-octylphenol, and p-nonylphenol. Phenais that are unsubstituted
in both positions ortho to the phenofic hydroxyl group are preferred in
preparing
the benzylic ether phenolic resole resins.

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The aldehydes reacted with the phenol include any of the aldehydes
heretofore used to prepare benzylic ether phenolic resole resins such as
formaldehyde, acetaldehyde, propionaldehyde, furfuraldehyde, and benzaldehyde.
In general, the aldehydes employed have the formula R'CHO wherein R' is a
hydrogen or a hydrocarbon radical of 1 to 8 carbon atoms. The most preferred
aldehyde is formaldehyde.
The benzylic ether phenolic resole resins are preferably non-aqueous. By
"non-aqueous" is meant a benzyiic ether phenolic resole resin which contains
water in amounts of no more than about 3%, preferably no more than about 1
based on the weight of the resin.
The benzyiic ether phenolic resole resin produced is preferably liquid or
soluble in an organic solvent. Solubility in an organic solvent is desirable
to
achieve uniform distribution of the phenolic resole resin component on the
aggregate used in making foundry cores and/or molds. Mixtures of benzyiic
ether
phenolic resole resins can be used.
Modified benzyfic ether phenolic resole resins can also be prepared by the
process. By modified, it is meant that all or some of the hydroxy methylene
groups
bonded to the phenolic rings have been converted into alkoxymethylene groups
by
etherification with aliphatic alcohols. Modified benzylic ether phenolic
resole
resins are prepared in essentially the same way as the unmodified benzylic
ether
phenofic resole resins previously described except a Power alkyl alcohol,
typically
methanol, is reacted with the phenol and aldehyde in situ, or the alcohol is
reacted
with an unmodified benzylic ether phenolic resole resin made in the presence
of
pressure. Alcohols which can be used for etherification include methanol,
ethanol and butanol, and polyhydric alcohols such as ethylene glycol,
propylene
glycol and the like. The amount of alcohol added to the charge is typically
from 0
to 0.5 moles per mole of phenol, preferably from 0 to 0.3 per moles of phenol.
When used in foundry binders, the benzylic ether phenoiic resole resin is
usually mixed with at least one organic solvent to form a benzylic ether
phenolic
resole resin component. Preferably the amount of solvent is from 40 to 60
weight
percent of total weight of the benzylic ether phenolic resole resin component.
Specific solvents and solvent combinations will be discussed later in
conjunction
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with the solvents used in the polyisocyanate component. The benzylic ether
phenolic resole resin component may also contain various optional ingredients
such as adhesion promoters, benchlife extenders, and release agents.
The benzyfic ether phenolic resole resin component is used in conjunction
with a separate organic polyisocyanate component to form the binder. The
organic polyisocyanate component typically is a polyisocyanate having a
functionality of two or more, preferably 2 to 5. It may be aliphatic,
cycloaliphatic,
aromatic, or a hybrid polyisocyanate. Mixtures of such polyisocyanates may be
used. In some situations, it may be possible to use prepolymers and
quasiprepolymers of poiyisocyanates. These are formed by reacting excess
polyisocyanate with compounds having two or more active hydrogen atoms, as
determined by the Zerewitinoff method. Optional ingredients such as benchlife
extenders may also be used in the organic polyisocyanate component in the cold-
box process for making foundry cores and/or molds.
Representative examples of polyisocyanates which can be used are
aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic
polyisocyanates such as 4,4'-dicyclohexyimethane diisocyanate, and aromatic
polyisocyanates such as 2,4- and 2,6-toluene diisocyanate, diphenylmethane
diisocyanate, and dimethyl derivatives thereof. Other examples of suitable
poiyisocyanates are 1,5-naphthalene diisocyanate, triphenylmethane
triisocyanate, xylylene diisocyanate, and the methyl derivates thereof,
polymethylenepolyphenyl isocyanates, chlorophenylene-2,4-diisocyanate, and the
like.
The polyisocyanates are used in sufficient concentrations to allow the
curing of the benzylic ether phenolic resole resin by the cold-box process
when
gassed with an amine curing catalyst, or by the no-bake process by mixing a
liquid
amine curing catalyst with the sand and binder and allowing it to cure in a
mold
andlor corebox. In general the isocyanate ratio of the poiyisocyanate to the
hydroxyl of the benzylic ether phenolic resole resin is from 0.75:1.25 to
1.25:0.75,
preferably about 0.9:1.1 to 1.1:0.9.
12

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
The polyisocyanate is used in a liquid form. Solid or viscous
polyisocyanates must be used in the form of organic solvent solutions, the
solvent
generally being present in a range of up to 80 percent by weight of the
solution.
Those skilled in the art will know how to select specific solvents for the
benzylic ether phenoiic resole resin component and organic polyisocyanate
hardener component. The organic solvents which are used with the benzylic
ether phenofic resole resin in the benzylic ether phenolic resole resin
component
are aromatic solvents, esters, ethers, and alcohols, preferably mixtures of
these
solvents.
It is known that the difference in the polarity between the polyisocyanate
and the benzylic ether phenolic resole resins restricts the choice of solvents
in
which both components are compatible. Such compatibility is necessary to
achieve complete reaction and curing of the binder compositions of the present
invention. Polar solvents of either the protic or aprotic type are good
solvents for
the benzylic ether phenolic resole resin, but have limited compatibility with
the
polyisocyanate.
The polar solvents should not be extremely polar such as to become
incompatible with the aromatic solvent. Suitable polar solvents are generally
those
which have been classified in the art as coupling solvents and include
furfural,
furfuryl alcohol, Cellosolve acetate, butyl Cellosolve, butyl Carbitol,
diacetone
alcohol, and Texanol. Other polar solvents include liquid dialkyl esters such
as
dialkyl phthalate of the type disclosed in U.S. Patent 3,905,934 and other
dialkyl
esters such as dimethyl glutarate.
Aromatic solvents, although compatible with the polyisocyanate, are less
compatible with the phenolic resole resins. It is, therefore, preferred to
employ
combinations of solvents and particularly combinations of aromatic and polar
solvents. Typical aromatic solvents are toluene, xylene, ethylbenzene, and
mixtures thereof. Preferred aromatic solvents are mixed solvents that have an
aromatic content of at least 90% and a boiling point range of 138°C to
232°C.
Drying oils, for example those disclosed in U.S. Patent 4,268,425, may also
be used in the polyisocyanate component. Drying oils may be synthetic or
naturally occur-ing and include glycerides of fatty acids which contain two or
more
13

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
double bonds whereby oxygen on exposure to air can be absorbed to give
peroxides which catalyze the polymerization of the unsaturated portions.
The binder system is preferably made available as a two-package system
with the benzylic ether phenoiic resole resin component in one package and the
polyisocyanate component in the other package. Usually, the binder components
are combined and then mixed with sand or a similar aggregate to form the
foundry
mix or the mix can be formed by sequentially mixing the components with the
aggregate. In the cold-box process, the benzyiic ether phenolic resole resin
component is first mixed with the sand before mixing the polyisocyanate
component with the sand. After mixing both components with the sand, the
foundry mix is shaped by blowing it into a corebox where it is contacted with
a
gaseous tertiary amine. When the no-bake process is used, the benzylic ether
phenolic resole resin component is (nixed with a liquid tertiary amine curing
catalyst and then mixed with the sand. The polyisocyanate component is then
mixed with the sand mix which is shaped and allowed to cure in a mold or
corebox.
The mix can, optionally, contain other ingredients such as benchlife
extenders,
iron oxide, ground flax fibers, wood cereals, pitch, refractory flours, and
the like.
Various types of aggregate and amounts of binder are used to prepare
foundry mixes by methods well known in the art. Ordinary shapes, shapes for
precision casting, and refractory shapes can be prepared by using the binder
systems and proper aggregate. The amount of binder and the type of aggregate
used is known to those skilled in the art. The preferred aggregate employed
for
preparing foundry mixes is sand wherein at least about 70 weight percent, and
preferably at least about 85 weight percent, of the sand is silica. Other
suitable
aggregate materials for ordinary foundry shapes include zircon, olivine,
aluminosilicate, sand, chromite sand, and the like.
In ordinary sand type foundry applications, the amount of binder is
generally no greater than about 10% by weight and frequently within the range
of
about 0.5% to about 7% by weight based upon the weight of the aggregate. Most
often, the binder content for ordinary sand foundry shapes ranges from about
0.6% to about 5% by weight based upon the weight of the aggregate in ordinary
sand-type foundry shapes.
14

CA 02260804 2005-06-14
Although the aggregate employed is preferably dry, small amounts of
moisture, generally up to about 1 weight percent based on the weight of the
sand, can be tolerated. This is particularly true if the solvent employE:d is
non-
water-miscible or if an excess of the polyisocyanate necessary for curing is
employed since such excess polyisocyanate will react with the water.
In the cold-box process, the foundry mix is molded into the desired shape
and cured by passing a tertiary amine through the molded mix such as described
in U.S. Patent 3,409,579 issued November 5, 1968. In the no-bake process, a
liquid amine curing catalyst is mixed with the benzylic ether phenolic resole
resin.
This mixture is then applied to the aggregate which is then mixed with the
polyisocyanate component. The total mixture is then placed in a mold where it
is
allowed to cure.
Another additive which can be added to the binder composition, usually
the benzylic ether phenolic resole resin component, in order to improve
humidity
resistance is a silane such as those described U.S. Patent 4,540,724.
ABBREVIATIONS AND DEFINITIONS USED IN THE EXAMPLE~i
Conventional Resin - a benzylic ether phenolic resole resin, whether
modified or unmodified made in an open
reaction vessel without pressure and used for
comparison purposes.
Distillate - water containing unreacted starting matE~rials
including organic compounds such as
formaldehyde, phenol, and methanol.
Endpoint - used for determining when the reaction to
produce the benzylic ether phenolic resin is
complete, typically when the free formaldehyde
content is 0.2% free formaldehyde by the
sodium sulfite test.

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
Modified resin - a benzylic ether phenolic resole resin, whether
made with or without pressure, which is modified
with an alcohol such as methanol.
MRS-5 - a polymeric organic polyisocyanate sold by Bayer
AG.
Open reaction
vessel - a reactor open to the air and which does not allow
pressure to accumulate.
Resin Under
Pressure - a benzylic ether phenolic resole resin made in a
sealed reaction vessel where pressure is generated
by applying heat to the reactants.
Sealed reaction
vessel - reaction vessel closed to the atmosphere
which will
accumulate pressure when the reactants
are
heated.
Unmodified
Resin - a benzylic ether phenolic resole resin,
whether
made in an open oi- closed reaction vessel
with or
without pressure, made without the addition
of an
alcohol.
M", - is the weight average molecular weight
as
determined by gei permeation chromatography
(GPC) using a column packed with divinyl
benzene
and a polystyrene calibration curve.
Yield - a percentage calculated by dividing the
weight of the
product that comes out of the reactor by
the weight of
16

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
the feed which goes into the reactor and then
multiplying by 100.
EXAMPLE 1 AND COMPARISON EXAMPLE A
COMPARISON OF AN UNMODIFIED BENZYLIC ETHER RESOLE RESIN
MADE IN AN OPEN REACTION VESSEL IN THE ABSENCE OF PRESSURE
TO ONE MADE IN A SEALED VESSEL IN THE PRESENCE OF PRESSURE
Example 1 illustrates the preparation of an unmodified benzyiic ether
phenolic resole resin (RESIN 1 ) within the scope of this invention. RESIN 1
was made in a sealed reaction vessel. Heat was applied to the reaction vessel
to generate pressure in the reaction vessel. The water formed by the reaction
was not removed from the reaction vessel until the endpoint for the resin was
reached. A commercially known and accepted resin (RESIN A) used in cold-
box binders, was used for comparison purposes. The comparison resin
(RESIN A) is a conventional, unmodified benzylic ether phenolic resole resin
prepared along the lines as the process described in U.S. Patent 3,409,579.
The resin was prepared in an open reaction vessel where pressure could not
accumulate. Water formed by the reaction was removed on a continuous basis
during part of the reaction. Table I describe the reaction conditions and
structural properties of RESIN A. Note that the benzylic ether to methylene
bridge ratio for RESIN A was 1.18:1Ø
The weight average molecular weights (MW) of RESIN 1 and RESIN A
were about the same. The weight average molecular weight for RESIN 1 was
about 1000 while the weight average molecular weight for RESIN A was about
991.
In order to prepare RESIN 1, the reactants were charged to a sealable
reactor, capable of maintaining the pressure produced by the reaction, in the
amounts set forth in Table I. The reactor was then sealed and the stirred
reaction mixture was heated to 113°C where it remained for about 60
minutes.
Then the temperature was raised to 125°C where it was held until the
free
formaldehyde concentration reached 0.07% by the sodium sulfite test.
17

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
During the course of the reaction, the pressure had gradually increased
to the maximum pressure stated in Table I. No water formed by the reaction
was removed up to this point. The pressure was then released while the
temperature was allowed to fat(. The vapors were passed through a condenser
and collected in a receiver. When the pressure had reached 0 psig and the
reaction temperature was at 100°C, a vacuum was applied. While holding
the
temperature at 100°C, water was vacuum distilled until the pressure had
fallen
to 100 mm. Hg. After 5 minutes at 100°C and 100 mm. Hg, the vacuum was
released, heating was stopped, and the resin yield was determined.
Although the weight average molecular weights of RESlN 1 and RESIN
A were almost the same, the benefits of preparing the unmodified benzylic
ether phenolic resole resin in a sealed reaction vessel, in the presence of
the
pressure accumulated by the reaction; are apparent as the data in Table I
indicate. In the process using a sealed reaction vessel, the amount of
distillate
was decreased, the resin yield increased, and the cycle time (CT) was
reduced. More particularly, the resin yield was 88.93% (2.01 % higher than the
conventional process carried out in an open reaction vessel) and the reaction
cycle time was 309 minutes (29 minutes shorter than in the conventional
process). Also significant is the amount of unreacted starting materials
produced by this process which was 15.5 weight percent compared to 30.6
weight percent produced by the conventional process. These results and
other results are set forth in Table I.
The physical and structure! properties of the unmodified benzylic ether
phenolic resole resin made with pressure and the unmodified benzyiic ether
phenolic resole resin made without pressure were also determined. Table II
sets forth the structural properties. The bolded items are the most
significant.
Particularly note the benzylic etheNmethylene bridge ratio for the unmodified
benzylic ether phenolic resole resin made in the presence of pressure which is
0.66, while the benzyiic ether/methylene bridge ratio for the unmodified
benzylic ether phenolic resole resin made without pressure is 1.18. Also note
the ortho/para substitution for the unmodified benzylic ether phenolic resole
resin, made in the presence of pressure, which is 5.71, while the ortho/para
18

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
substitution for the unmodified benzylic ether phenolic resole resin made in
the absence of pressure is 7.40.
19

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
0
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T

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
Dogbone shaped sand cores were made with Resin A. The resin
component of the binder contained 55 parts by weight of RESIN A and 45 parts
by weight of aromatic solvents, ester solvents, release agents, and silane.
The
organic polyisocyanate component contained about 75 parts by weight of
MRS-5 as the organic polyisocyanate and 25 parts by weight of aromatic
solvent, ester solvents, vegetable oil, and benchfife extender. A similar
resin
component was formulated using RESIN 1 which was used with a similar
organic polyisocyanate component described as Part II except 80 parts by
weight of MRS-5 was used and the other components were adjusted
accordingly. The results are summarized in Table III. The data indicate that
the cores made with RESIN 1 are comparable to those made with RESIN A
even though the benzylic ether/methylene bridge ratio for RESlN 1 was only
0.66. The benzylic etheNmethylene bridge ratio for RESIN A was 1.18:1.0
which corresponds to a benzylic etherlmethylene bridge ratio shown to be
preferred by the prior art.
21

CA 02260804 1999-O1-18
WO 98!02473 PCT/IB96/00787
TABLE III
SAND TEST COMPARISONS USING RESIN 1 MADE AT NCO/OH = 0.95
CONDITIONS
Sand: 40008. Maniey 11-5W
CT3 Room: 50°.6 Relative Humidity, 25°C
Sand Lab: 33% Relative Humidity, 22°C
Binder: 1.3°~ Based on sand, Part I/Part il = 55/45
TENSILE
PROPERTIES,
PSI
ZE RO 3
BENCH HR.
BENCH
EXAMPLE PART PART IMM 5 1 24 100% IMM 24
I II MIN.HR. HR. RH HR.
CONTROL RESIN X 128 155 165 182 33 99 164
B A
2 RESIN Y 129 162 168 203 39 98 161
1
Castings were produced using cores made from binders containing
RESIN 1 and Resin A. Grey iron castings were poured at about
1,500° C
around 2" X 2" cylindrical cores made with binders using RESIN 1 and RESIN
A . The binder used were the same binders used in Example 2 and Control B.
The amount of binder used to make the cores was 1.3 % based on the sand.
The castings were evaluated with respect to penetration resistance,
veining, and surface finish by the Penetration Casting 2" X 2" Test Casting
based upon a modification of a design used by Murton and Gertsman for the
investigation of metal penetration. The test is used extensively not only to
evaluate penetration resistance, but veining and surface finish. After the
metal is poured and cooled, the casting is observed and graded with respect to
penetration resistance, veining, and surface finish.
The casting results are shown in Table IV. Table IV indicates that the
castings, made with cores using the unmodified resins synthesized in a sealed
reaction vessel under pressure showed less penetration. See column in the
table related to penetration. Metal penetration occurs when metal or metal
oxides fill the voids between the sand grains of the core without displacing
3 CT = constant temperature/humidity room.
22

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
them or chemically changing the silica or binder. When there is penetration in
a casting, the casting will require repair or be discarded as scrap. This
increases cost and decreases efficiency in the foundry.
TABLE IV
CASTING TESTS MADE USING A CONVENTIONAL RESIN
AND A BENZYLIC ETHER PHENOLIC RESOLE RESIN
MADE UNDER PRESSURE
Casting Grade: 1= Excel lent, 2=Good, 3=Fair, 4=Poor, 5=Very Poor
EXAMPLES 4-5
MODIFIED RESINS MADE AT VARYING PRESSURE
In Examples 4-5, modified benzylic ether phenolic resole resins
(modified with methanol) were, prepared in a sealed reaction vessel such that
the pressure generated by the reaction varied from 20 psig to 40 psig. The
procedure followed for preparing the modified benzylic ether phenolic resole
resins was essentially the same as that followed in Example 1 except methanol
was added to the charge, and the final temperature at which the reaction
mixture was held until the free formaldehyde end point was reached is shown
in Table V (Max. °C). Table V which follows shows the results of
generating
higher pressures in the sealed reactor. Note that the cycle time decreased
from 405 minutes to 271 minutes and the yield of resin per unit of time
increased when pressure generated in the sealed reaction vessel increased
from 20 psig to 40 psig. These results and other results are set forth in
Table
V.
The physical and structural properties of the benzyiic ether phenolic
resole resins modified with methanol were also determined. Table VI sets forth
the structural properties for the resins made in accordance with Examples 4-5.
23

CA 02260804 1999-O1-18
WO 98102473 PCT/IB96/00787
Note that the benzylic ether/methylene bridge ratio (in bold print) was about
the same, namely 0.62 in Example 4 and 0.65 for Example 5. Moreover, the
benzyiic ether/methylene bridge ratio of resins, made when pressure was
generated in the reaction vessel, is evidently not substantially influenced by
methanol modification since RESIN 1, described in Example 1 as an
unmodified benzylic ether phenolic resole resin made in a sealed reaction
vessel, had a dimethylene ether/methylene bridge ratio bridge ratio of 0.66.
24

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
H
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T

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96100787
EXAMPLES 6-7
EFFECT OF PHENOL TO FORMALDEHYDE RATIO
Examples 6-7 illustrate the effect of the formaldehyde/phenol ratio on 1-
butanol modified benzylic ether phenolic resole resins prepared in a seated
reaction vessel where the pressure in the reaction vessel is essentially the
same, i.e. about 25 psig. The formaldehyde to phenol ratios used were 1.1:1.0
and 1.2:1Ø
The procedure for preparing the modified benzylic ether phenolic resole
resins was essentially the same as that followed in Examples 4-5 except 1-
butanol was used as the modifier. The charges of the reactants are specified
in Table VII. Table VIII sets forth the structural properties of the modified
benzylic ether phenolic resole resins.
The results in Table VII indicate that yield increases per unit of time and
cycle time decreases at lower formaldehyde to phenol ratios. Table VIII
indicates that the ether to methylene bridge ratio for these resins modified
with
1-butanol is higher than the unmodified resins and those modified with
methanol, but the ratios are still < 1.
26

CA 02260804 1999-O1-18
WO 98/02473 PCT/IB96/00787
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27