U.S. patent application number 10/626189 was filed with the patent office on 2005-01-27 for stabilized phenolic resole resin compositions and their use.
Invention is credited to Chen, Chia-hung, Kroker, Jorg, Wang, Xianping.
Application Number | 20050020723 10/626189 |
Document ID | / |
Family ID | 34080367 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050020723 |
Kind Code |
A1 |
Chen, Chia-hung ; et
al. |
January 27, 2005 |
Stabilized phenolic resole resin compositions and their use
Abstract
This invention relates to a stabilized phenolic resole resin
composition comprising a phenolic resole resin and an effective
stabilizing amount of an ortho ester. The invention also relates to
phenolic urethane binders prepared with the phenolic resole resin
compositions, and the use of the binders to make foundry mixes,
foundry shapes, and metal castings.
Inventors: |
Chen, Chia-hung; (Dublin,
OH) ; Wang, Xianping; (Dublin, OH) ; Kroker,
Jorg; (Powell, OH) |
Correspondence
Address: |
David L. Hedden
ASHLAND INC.
P.O. Box 2219
Columbus
OH
43216
US
|
Family ID: |
34080367 |
Appl. No.: |
10/626189 |
Filed: |
July 24, 2003 |
Current U.S.
Class: |
523/139 |
Current CPC
Class: |
B22C 1/2266 20130101;
B22C 1/2253 20130101 |
Class at
Publication: |
523/139 |
International
Class: |
B22C 001/00 |
Claims
We claim:
1. A stabilized phenolic resole resin composition comprising a
phenolic resin and an effective stabilizing amount of an ortho
ester.
2. The stabilized phenolic resole resin composition of claim 1
which also contains a solvent selected from the group consisting of
aromatic hydrocarbon solvents, ester solvents, and mixtures
thereof.
3. The stabilized phenolic resole resin composition of claim 2
wherein the stabilized phenolic resole resin composition comprises
a polybenzylic ether phenolic resin prepared by reacting an
aldehyde with a phenol such that the molar ratio of aldehyde to
phenol is from 1.1:1 to 3:1 in the presence of a divalent metal
catalyst.
4. The stabilized phenolic resole resin composition of claim 3
wherein the phenol used to prepare the phenolic resole resin of the
stabilized phenolic resole resin composition is selected from the
group consisting of phenol, bisphenol, o-cresol, p-cresol, and
mixtures thereof.
5. The stabilized phenolic resole resin composition of claim 4
wherein the aldehyde used to prepare the phenolic resin of the
stabilized phenolic resole resin composition is formaldehyde.
6. The stabilized phenolic resole resin composition of claim 5
wherein the ortho ester is selected from the group consisting of
triethyl orthoformate, trimethyl orthoformate, and mixtures
thereof.
7. The stabilized phenolic resole resin composition of claim 6
wherein the amount of solvent in the resin composition is from 20
weight percent to 80 weight percent based upon the weight of the
phenolic resin composition.
8. The stabilized phenolic resole resin composition of claim 7
wherein the amount of ortho ester is from about 0.1 weight percent
to about 1.5 weight percent based upon the weight of the phenolic
resin.
9. The stabilized phenolic resole resin composition of claim 6
wherein the phenolic resole resin of the stabilized phenolic resole
resin composition is an alkoxy-modified benzylic ether phenolic
resole resin and the catalyst used to prepare said resin is a
divalent zinc salt.
10. A foundry binder system comprising the phenolic resole resin
component of claim 1, 2, 3, 4, 5, 6, 7, 8, or 9 and a
polyisocyanate component.
11. A foundry mix comprising: A. a major amount of an aggregate;
and B. an effective bonding amount of the binder system of claim
10.
12. A process for preparing a foundry shape which comprises: (a)
forming a foundry mix as set forth in claim 10; (b) forming a
foundry shape by introducing the foundry mix obtained from step (a)
into a pattern; (c) contacting the shaped foundry binder system
with a tertiary amine catalyst; and (d) removing the foundry shape
of step (c) from the pattern.
12. The process of claim 11 wherein the tertiary amine catalyst is
a gaseous tertiary amine catalyst.
13. The process of claim 12 wherein the amount of said binder
composition is about 0.6 percent to about 5.0 percent based upon
the weight of the aggregate.
14. The process of claim 10 wherein the tertiary amine catalyst is
a liquid tertiary amine catalyst.
15. The process of casting a metal which comprises: (a) preparing a
foundry shape in accordance with claim 12; (b) pouring said metal
while in the liquid state into and a round said shape; (c) allowing
said metal to cool and solidify; and (d) then separating the molded
article.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to a stabilized phenolic resole resin
composition comprising a phenolic resole resin and an effective
stabilizing amount of an ortho ester. The invention also relates to
phenolic urethane binders prepared with the phenolic resole resin
compositions, and the use of the binders to make foundry mixes,
foundry shapes, and metal castings.
BACKGROUND OF THE INVENTION
[0002] One of the major processes used in the foundry industry for
making metal parts is sand casting. In sand casting, disposable
foundry shapes (usually characterized as molds and cores) are made
by shaping and curing a foundry binder system that is a mixture of
sand and an organic or inorganic binder. The binder is used to
strengthen the molds and cores.
[0003] Two of the major processes used in sand casting for making
molds and cores are the no-bake process and the cold-box process.
In the no-bake process, a liquid curing agent is mixed with an
aggregate and shaped to produce a cured mold and/or core. In the
cold-box process, a gaseous curing agent is passed through a
compacted shaped mix to produce a cured mold and/or core. Phenolic
urethane binder, cured with a gaseous tertiary amine catalyst, are
often used in the cold-box process to hold shaped foundry aggregate
together as a mold or core. See for example U.S. Pat. No.
3,409,579. The phenolic urethane binder system usually consists of
a phenolic resin component and polyisocyanate component, which are
mixed with sand prior to compacting and curing to form a foundry
binder system.
[0004] Among other things, the binder must have a low viscosity, be
gel-free, remain stable under use conditions, and cure efficiently.
The foundry binder system made by mixing sand with the binder must
have adequate benchlife or the mix will not shape and cure
properly. The cores and molds made with the binders must have
adequate tensile strengths under normal and humid conditions, and
release effectively from the pattern. Binders that meet all of
these requirements are not easy to develop.
[0005] One of the problems with the phenolic resole resins used in
phenolic urethane binders is that they are heat sensitive, and thus
are not stable when stored at or exposed to elevated temperature
for a prolonged period of time. This causes the viscosity of the
resin to increase, or in extreme cases, the resin will gel. This
seriously adversely affects the quality and performance of the
binder.
[0006] Ortho esters are known in the prior art to stabilize organic
isocyanates. U.S. Pat. No. 3,535,359 (Chadwick) discloses that
certain ortho-esters are capable of stabilizing a polyisocyanate
against several different kinds of degradation, for instance
moisture, and viscosity increases, even when only small amounts of
ortho esters are used. The stabilized isocyanates are useful in the
preparation of polyurethane foam, nonporous plastics including
polyurethane castings such as gear wheels and the like, and coating
compositions. Chadwick does not disclose the use of such
polyisocyanates in foundry binders, foundry mixes, or the
preparation of foundry shapes and metal castings.
[0007] U.S. Pat. No 6,288,139 discloses phenolic urethane binders
wherein the polyisocyanate component contains an ortho ester. The
patent indicates that, when added to a polyisocyanate component
that contains a non reactive organic solvent, the ortho ester
improves the tensile strength of foundry shapes. It also indicates
that polyisocyanate components containing the ortho ester have
lower turbidity, which indicates that it is more stable or
homogeneous. As a result the polyisocyanate component will not be
subjected to settling of particulate matter, and will be easier to
pump. This patent does not teach or suggest the use of ortho esters
in the phenolic resole resin component of the phenolic urethane
binder.
SUMMARY OF THE INVENTION
[0008] This invention relates to stabilized phenolic resole resin
compositions comprising a phenolic resole resin and an effective
stabilizing amount of an ortho ester. The invention also relates to
phenolic urethane binders prepared with the phenolic resole resin
compositions, and the use of the binders to make foundry mixes,
foundry shapes, and metal castings.
[0009] The addition of the ortho ester was found to be an effective
stabilizing agent to improve the shelf stability of the phenolic
resole resin composition. The advantages of using the ortho ester
in the phenolic resole resin composition are:
[0010] (1) the phenolic resole resin composition has better shelf
storage stability if it contains the ortho ester, and
[0011] (2) the phenolic resole resin composition has improved heat
stability at elevated temperatures if it contains the ortho
ester.
[0012] Shelf stability and heat stability are demonstrated because
the phenolic resole resin composition does not undergo viscosity
increase or gelation, even when subjected to increased
temperatures. This advantage is particular important when the
phenolic resole resin composition is stored and exposed at elevated
temperatures during summer time.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The phenolic resole resin used in the phenolic resole resin
composition is preferably prepared by reacting an excess of
aldehyde with a phenol in the presence of either an alkaline
catalyst or a metal catalyst. The phenolic resins are preferably
substantially free of water and are organic solvent soluble. The
preferred phenolic resins used in the subject binder compositions
are well known in the art, and are specifically described in U.S.
Pat. No 3,485,797, which is hereby incorporated by reference. These
resins, known as benzylic ether phenolic resole resins, are the
reaction products of an aldehyde with a phenol. They contain a
preponderance of bridges joining the phenolic nuclei of the
polymer, which are ortho-ortho benzylic ether bridges. They are
prepared by reacting an aldehyde and a phenol in a mole ratio of
aldehyde to phenol of at least 1:1 in the presence of a metal ion
catalyst, preferably a divalent metal ion such as zinc, lead,
manganese, copper, tin, magnesium, cobalt, calcium, and barium.
[0014] Alkoxy-modified benzylic ether phenolic resole resins can
also be used. The resins are prepared by reacting an excess of
aldehyde with a phenol and an alcohol in the presence of a metal
ion catalyst according to methods well known in the art.
Alternatively, they can be prepared by preparing a benzylic ether
phenolic resole resin and post-capping with the alcohol. See, for
example, U.S. Pat. No 4,546,124 for a discussion of how these
resins are prepared.
[0015] The phenols use to prepare the phenolic resole resins
include any one or more of the phenols which have heretofore been
employed in the formation of phenolic resins and which are not
substituted at either the two ortho-positions or at one
ortho-position and the para-position. These unsubstituted positions
are necessary for the polymerization reaction. Any of the remaining
carbon atoms of the phenol ring can be substituted. The nature of
the substituent can vary widely and it is only necessary that the
substituent not interfere in the polymerization of the aldehyde
with the phenol at the ortho-position and/or para-position.
Substituted phenols employed in the formation of the phenolic
resins include alkyl-substituted phenols, aryl-substituted phenols,
cyclo-alkyl-substituted phenols, aryloxy-substituted phenols, and
halogen-substituted phenols, the foregoing substituents containing
from 1 to 26 carbon atoms and preferably from 1 to 12 carbon
atoms.
[0016] Specific examples of suitable phenols include phenol,
2,6-xylenol, o-cresol, p-cresol, 3,5-xylenol, 3,4-xylenol,
2,3,4-trimethyl phenol, 3-ethyl phenol, 3,5-diethyl phenol, p-butyl
phenol, 3,5-dibutyl phenol, p-amyl phenol, p-cyclohexyl phenol,
p-octyl phenol, 3,5-dicyclohexyl phenol, p-phenyl phenol, p-crotyl
phenol, 3,5-dimethoxy phenol, 3,4,5-trimethoxy phenol, p-ethoxy
phenol, p-butoxy phenol, 3-methyl-4-methoxy phenol, and p-phenoxy
phenol. Multiple ring phenols such as bisphenol A and bisphenol F
are also suitable.
[0017] The aldehyde used to react with the phenol has the formula
RCHO wherein R is a hydrogen or hydrocarbon radical of 1 to 8
carbon atoms. The aldehydes reacted with the phenol can include any
of the aldehydes heretofore employed in the formation of phenolic
resins such as formaldehyde, acetaldehyde, propionaldehyde,
furfuraldehyde, and benzaldehyde. The most preferred aldehyde is
formaldehyde.
[0018] The phenolic resin used must be liquid or organic
solvent-soluble. The phenolic resin composition generally contains
an organic solvent. The amount of solvent used should be sufficient
to result in a binder composition permitting uniform coating
thereof on the aggregate and uniform reaction of the mixture. The
specific solvent concentration for the phenolic resin composition
will vary depending on the type of phenolic resin employed and its
molecular weight. In general, the solvent concentration will be in
the range of up to 80% by weight of the resin solution and
preferably in the range of 20% to 80%.
[0019] As was mentioned previously, the phenolic resole resin
composition contains an ortho ester. The ortho esters used have the
formula R'C(OR).sub.3, where R' is hydrogen, alkyl, alkenyl, aryl,
haloalkyl and R is alky or alkenyl of 1 to 18 carbon atoms,
chloroethyl, or phenyl. The ortho esters are disclosed in U.S. Pat.
No 3,535,359, which is incorporated by reference into this
specification. Preferably used are triethyl orthoformate, trimethyl
orthoformate, and mixtures thereof. The amount of ortho ester used
is from 0.1 to 5.0 weight percent based upon the weight of the
phenolic resole resin, preferably from 0.1 to 1.5 weight percent,
most preferably from 0.1 to 0.4 weight percent
[0020] The phenolic resole resin compositions are used in the
phenolic urethane binders. These binders contain a phenolic resin
component and a polyisocyanate component, and are typically cured
with a tertiary amine curing catalyst.
[0021] The polyisocyanate component of the binder typically
comprises a polyisocyanate and organic solvent. The polyisocyanate
has 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. Also, it is
contemplated that capped polyisocyanates, prepolymers of
polyisocyanates, and quasi prepolymers of polyisocyanates can be
used. Optional ingredients such as release agents may also be used
in the polyisocyanate hardener component.
[0022] Representative examples of polyisocyanates which can be used
are aliphatic polyisocyanates such as hexamethylene diisocyanate,
alicyclic polyisocyanates such as 4,4'-dicyclohexylmethane
diisocyanate, and aromatic polyisocyanates such as 2,4-, 2,4-,
2,6-toluene diisocyanate and 2,2'-, 2,4'-, 4,4'-diphenylmethane
diisocyanate, and dimethyl derivates thereof. Other examples of
suitable polyisocyanates are 1,5-naphthalene diisocyanate,
triphenylmethane triisocyanate, xylylene diisocyanate, and the
methyl derivates thereof, polymethylenepolyphenyl isocyanates,
chlorophenylene-2,4-diisocyanate, and the like.
[0023] The polyisocyanates are used in sufficient concentrations to
cause the curing of the phenolic resin in the presence of the
curing catalyst. In general the polyisocyanate ratio of the
polyisocyanate to the hydroxyl of the phenolic resin is from 1.25:1
to 1:1.25, preferably about 1:1. Expressed as weight percent, the
amount of polyisocyanate used is from 10 to 500 weight percent,
preferably 20 to 300 weight percent, based on the weight of the
phenolic resin.
[0024] The polyisocyanate is used in a liquid form. Solid or
viscous polyisocyanate must be used in the form of organic solvent
solutions. In general, the solvent concentration will be in the
range of up to 80% by weight of the resin solution and preferably
in the range of 20% to 80%.
[0025] Those skilled in the art will know how to select specific
solvents for the phenolic resin component, and in particular the
solvents required in the polyisocyanate component. It is known that
the difference in the polarity between the polyisocyanate and the
phenolic 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 phenolic resin, but have
limited compatibility with the polyisocyanate. Aromatic solvents,
although compatible with the polyisocyanate, are less compatible
with the phenolic results. It is, therefore, preferred to employ
combinations of solvents and particularly combinations of aromatic
and polar solvents.
[0026] Examples of aromatic solvents include xylene and
ethylbenzene. The aromatic solvents are preferably a mixture of
aromatic solvents that have a boiling point range of 125.degree. C.
to 250.degree. C. 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".
[0027] The binder may also contain a silane (typically added to the
phenolic resin component) having the following general formula:
1
[0028] wherein R' is a hydrocarbon radical and preferably an alkyl
radical of 1 to 6 carbon atoms and R is an alkyl radical, an
alkoxy-substituted alkyl radical, or an alkyl-amine-substituted
alkyl radical in which the alkyl groups have from 1 to 6 carbon
atoms. The silane is preferably added to the phenolic resin
component in amounts of 0.01 to 2 weight percent, preferably 0.1 to
0.5 weight percent based on the weight of the phenolic resin
component.
[0029] When preparing an ordinary sand-type foundry shape, the
aggregate employed has a particle size large enough to provide
sufficient porosity in the foundry shape to permit escape of
volatiles from the shape during the casting operation. The term
"ordinary sand-type foundry shapes," as used herein, refers to
foundry shapes which have sufficient porosity to permit escape of
volatiles from it during the casting operation.
[0030] The preferred aggregate employed for preparing ordinary
foundry shapes is silica wherein at least about 70 weight percent
and preferably at least about 85 weight percent of the sand is
silica. Other suitable aggregate materials include zircon, olivine,
aluminosilicate,=Remove Comma sand, chromite sand, and the like.
Although the aggregate employed is preferably dry, it can contain
minor amounts of moisture.
[0031] In molding compositions, the aggregate constitutes the major
constituent and the binder constitutes a relatively minor amount.
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 ranges from about
0.6% to about 5% by weight based upon the weight of the aggregate
in ordinary sand-type foundry shapes.
[0032] The binder compositions are preferably made available as a
two-package system with the phenolic resin component in one package
and the polyisocyanate component in the other package. Usually, the
phenolic resin component is first mixed with sand and then the
polyisocyanate component is added. Methods of distributing the
binder on the aggregate particles are well known to those skilled
in the art.
[0033] The foundry binder system is molded into the desired shape,
such as a mold or core, and cured. Curing by the cold-box process
is carried out by passing a volatile tertiary amine, preferably
triethyl amine, through the shaped mix as described in U.S. Pat. No
3,409,579. Curing by the no-bake process takes place by mixing a
liquid amine curing catalyst into the foundry binder system,
shaping it, and allowing it to cure.
[0034] Useful liquid amines have a pK.sub.b value generally in the
range of about 7 to about 11. Specific examples of such amines
include 4-alkyl pyridines, isoquinoline, arylpyridines,
1-methylbenzimidazole, and 1,4-thiazine. Preferably used as the
liquid tertiary amine catalyst is an aliphatic tertiary amine,
particularly tris (3-dimethylamino) propylamine. In general, the
concentration of the liquid amine catalyst will range from about
0.2 to about 5.0 percent by weight of the phenolic resin,
preferably 1.0 percent by weight to 4.0 percent by weight, most
preferably 2.0 percent by weight to 3.5 percent by weight based
upon the weight of the phenolic resin.
EXAMPLES
[0035] While the invention has been described with reference to a
preferred embodiment, those skilled in the art will understand that
various changes may be made and equivalents may be substituted for
elements thereof without departing from the scope of the invention.
In addition, many modifications may be made to adapt a particular
situation or material to the teachings of the invention without
departing from the essential scope thereof. Therefore, it is
intended that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all embodiments
falling within the scope of the appended claims. In this
application, all amounts and percentages are by weight, unless
otherwise expressly indicated. The following abbreviations are used
in the examples:
[0036] TMOF trimethyl ortho-formate.
[0037] PEP SET.RTM. 1670/2670 a phenolic urethane no-bake foundry
binder, manufactured by Ashland Specialty Chemical Company. PEP SET
1670 is the phenolic component and comprises about 50-60 weight
percent PR, 20-30 weight percent aromatic solvent, and 10-20 weight
percent ester solvent. PEP SET 2670 is the isocyanate component and
comprises about 60-80 weight percent isocyanate, and 30-40 weight
percent aromatic solvents.
[0038] PR a polybenzylic ether phenolic resin prepared with zinc
acetate dihydrate as the catalyst and modified with the addition of
0.09 mole of methanol per mole of phenol prepared along the lines
described in the examples of U.S. Pat. No 3,485,797.
[0039] Wedron 540 sand silica sand commonly used in the foundry
industry.
[0040] RH relative humidity.
[0041] ST striptime is the time interval for a foundry mix to reach
a green hardness of 90.
[0042] WT worktime is the time interval for a foundry mix to reach
a green hardness of 60.
[0043] The following examples demonstrate the use of TMOF in
phenolic urethane no-bake foundry binder applications.
Examples A, 1, and 2
(Heat Stability Tests of Phenolic Resins)
[0044] In order to test the heat stability of the phenolic resin
compositions with and without TMOF, 200 grams of PEP SET 1670
binder were placed in 8-oz plastic bottles. The samples were stored
at 60.degree. C. for 80 days. The viscosity of the samples was
measured after 1 day and after 80 days by using Brookfield
viscosity cone and plate viscosity method. The results are
summarized in Table I.
1TABLE I (Effect of TMOF on the Heat Stability of Phenolic
Component) (Samples stored at 60.degree. C. for 80 days) Phenolic
Viscosity (cp) component TMOF.sup.1 Day 1 Day 80 Control A.sup.2
0.0 165 >1,000,000, partially gelled Example 1 0.7 163 2,640
Example 2 1.4 162 862 .sup.1Weight percent based upon the weight of
the phenolic resin component. .sup.2PEP SET .RTM. 1670 phenolic
resin component
[0045] Table I shows that the incorporation of TMOF as stabilizing
agent at levels of 0.7 and 1.4% by weight into the phenolic
component (PEP SET 1670) greatly improved the shelf storage
stability of the phenolic component at 60.degree. C. The control
sample (A) gelled out, while Example 1 and 2 were pourable liquids
after 80 days storage at 60.degree. C. Table I also indicates that
the higher level of TMOF used, the greater the heat stability of
the phenolic resole resin component. This is particular important
during the hot summer time, where the temperature can reach
50.degree. C. during the shipping and handling of the foundry
binder.
Examples B, 3, and 4
(Effect of Using TMOF on Strength of Cores Made with Binder)
[0046] Test cores were made with PEP SETS.RTM. 1670/2670 using
Wedron 540 sand at a binder level of 1.2%, based upon the weight of
the sand, a Part I/Part II mix ratio of 55/45 mix ratio, and PEP
SET 3502 catalyst (4-phenyl propyl pyridine in an aromatic solvent)
in an amount of about 3 weight percent based upon the Part I.
[0047] Tensile strengths of test dog bone shapes were measured
according to the AFS standard tensile strength test. Determining
the tensile strengths of the dog bone test shapes enables one to
predict how the mixture of sand and binder will work in actual
foundry facilities. The dog bones were stored for 1.0 hour, 3 hours
and 24 hours in a constant temperature room at relative humidity of
50% and a temperature of 25.degree. C. before measuring their
tensile strengths. Unless otherwise specified, the tensile
strengths were also measured on dog bone specimens stored 24 hours
at a relative humidity (RH) of 90%. The results of these tests are
shown in Table II.
2TABLE II (Effect of TMOF on sand tensile performance) WT/ST 1 Hr 3
Hrs 24 Hrs 24 Hr Binder TMOF level.sup.3 (min) [psi] @ 90% RH
Control B 0.0 3.0/4.0 152 166 200 70 Example 3 0.7 3.8/4.2 159 181
212 65 Example 4 1.4 3.5/4.2 136 192 185 63 .sup.3Weight percent
based upon the weight of the phenolic resin component
[0048] The data indicate that addition of TMOF to the phenolic
resole resin component has little effect on the sand tensile
strength development. The data in Tables I and II indicate that
adding TMOF into the phenolic resin component, while increasing the
heat stability of the phenolic resin component, does not adversely
effect the desired core-making properties.
Examples C, 5, and 6
(Heat Stability Tests of Phenolic Resins Where Zinc Catalyst Was
Removed)
[0049] The procedure of Examples A, 1, and 2 was followed, except
the zinc catalyst used to make the resin was removed from the
resin. The results are summarized in Table III.
3TABLE III (Effect of TMOF on the Heat Stability of Phenolic
Component) (Samples stored at 60.degree. C. for 80 days) Phenolic
Viscosity (cp) component TMOF.sup.4 Day 1 Day 80 Control C 0.0 75
595 Example 5 0.7 74 367 Example 6 1.4 73 319 .sup.4Weight percent
based upon the weight of the phenolic resin component.
[0050] The data in Table III indicate that the phenolic resole
resin component without the zinc catalyst had a much lower
viscosity to begin with. However, the effect of TMOF on the heat
stability of the phenolic component is still evident. The addition
of TMOF to the phenolic resin component improved the heat stability
of the phenolic resin component, which is shown by the data
indicating that there was little change in viscosity in the samples
containing the TMOF.
Examples D, 7, and 8
(Effect of Using TMOF on Strength of Cores Made with Binder)
[0051] Test cores using the procedure set forth in Examples B, 3,
and 4, except the phenolic resin of Examples C, 5, and 6, which had
the zinc catalyst removed, was used as the resin. The results of
these tests are shown in Table IV.
4TABLE II (Effect of TMOF on sand tensile performance) WT/ST 1 Hr 3
Hrs 24 Hrs 24 Hr Binder TMOF level.sup.5 (min) [psi] @ 90% RH
Control D 0.0 6.5/7.5 157 186 235 102 Example 7 0.7 7.0/8.3 133 183
253 104 Example 8 1.4 8.5/10.2 111 158 206 103 .sup.5Weight percent
based upon the weight of the phenolic resin component
[0052] The data in Table IV indicate that addition of TMOF to the
phenolic resole resin component in this case had some adverse
affect on the core strength, particularly at the 1.4% level. It is
noted that the presence of TMOF slightly increases the work
time/strip time of this no-bake binder. However, these adverse
affects are not a problem from commercial standpoint, and the
advantages that the use of TMOF provides in terms of increased heat
stability outweighs these disadvantages.
* * * * *