U.S. patent application number 12/793071 was filed with the patent office on 2011-06-02 for foundry binder comprising one or more cycloalkanes as a solvent.
This patent application is currently assigned to Ashland Licensing and Intellectual Property LLC. Invention is credited to Jorg Kroker, Mark Richard Stancliffe, Xianping Wang.
Application Number | 20110129387 12/793071 |
Document ID | / |
Family ID | 43449668 |
Filed Date | 2011-06-02 |
United States Patent
Application |
20110129387 |
Kind Code |
A1 |
Stancliffe; Mark Richard ;
et al. |
June 2, 2011 |
FOUNDRY BINDER COMPRISING ONE OR MORE CYCLOALKANES AS A SOLVENT
Abstract
A foundry binder comprising (a) a polyol component selected from
the group consisting of phenolic resins, polyether polyols,
polyester polyols, aminopolyols, and mixtures thereof, and (b) a
polyisocyanate component, wherein component (a) and/or (b) further
comprise, as a solvent, one or more cycloalkanes.
Inventors: |
Stancliffe; Mark Richard;
(Bromyard, GB) ; Kroker; Jorg; (Powell, OH)
; Wang; Xianping; (Dublin, OH) |
Assignee: |
Ashland Licensing and Intellectual
Property LLC
|
Family ID: |
43449668 |
Appl. No.: |
12/793071 |
Filed: |
June 3, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61266036 |
Dec 2, 2009 |
|
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Current U.S.
Class: |
420/591 ;
164/131; 164/16; 164/526; 523/143 |
Current CPC
Class: |
B22C 1/2253 20130101;
B22C 1/2213 20130101 |
Class at
Publication: |
420/591 ;
523/143; 164/16; 164/131; 164/526 |
International
Class: |
B22D 29/00 20060101
B22D029/00; B22C 1/22 20060101 B22C001/22; B22C 9/02 20060101
B22C009/02 |
Claims
1. A foundry binder comprising: (a) a polyol component selected
from the group consisting of phenolic resins, polyether polyols,
polyester polyols, amine polyols, and mixtures thereof, (b) a
polyisocyanate component; and wherein component (a) and/or
component (b) further comprise, as a solvent, one or more
cycloalkanes selected from the group consisting of unsubstituted
cycloalkanes, substituted cycloalkanes, and mixtures thereof.
2. The foundry binder of claim 1 wherein the polyol component
comprises a phenolic resole resin.
3. The foundry binder of claim 2 wherein the number of carbon atoms
in the cycloalkane is from 5 to 24.
4. The foundry binder of claim 3 wherein the number of rings in the
cycloalkane is from 1 to 4.
5. The foundry binder of claim 3 wherein the number of carbon atoms
in the rings of the cycloalkanes is from 4 to 10.
6. The foundry binder of claim 5 wherein one or more of the
cycloalkanes has 2 rings.
7. The foundry binder of claim 2 wherein the cycloalkane is
selected from the group consisting of cylcohexane, trimethyl
cyclohexane, decahydronaphthalene, tetrahydronaphthalene, and
mixtures thereof.
8. The foundry binder of claim 2 wherein the cycloalkane comprises
decahydronaphthalene.
9. The foundry binder of claim 1, 2, 3, 4, 5, 6, 7, or 8 wherein
component (a) and/or component (b) further comprise one or more
solvents selected from the group consisting of aromatic hydrocarbon
solvents, ester solvents, fatty acid ester solvents, and mixtures
thereof.
10. The foundry binder of claim 9 wherein the amount of cycloalkane
in the binder system is from 5 to 40 parts by weight based upon 100
parts by weight of the binder.
11. The foundry binder of claim 10 wherein the amount of aromatic
hydrocarbon solvents is less than 10 parts by weight based upon 100
parts by weight of the binder.
12. The foundry binder of claim 11 wherein the binder does not
contain aromatic hydrocarbon solvents.
13. A foundry mix comprising a major amount of a refractory and a
minor amount of the foundry binder of claim 9.
14. The foundry mix of claim 13 which further comprises a liquid
tertiary amine curing catalyst.
15. A cold-box process for preparing a foundry shape comprising:
(a) introducing a major amount of the composition of claim 9 into a
pattern to form a shape; (b) contacting the shape with the vapor of
a tertiary amine curing catalyst; (c) allowing the shape to cure;
and (d) removing the shape from the pattern.
16. A process for casting a metal part comprising: (a) inserting a
foundry shape prepared in accordance with claim 15 into a casting
assembly having one or more molds and/or cores; (b) pouring metal,
while in the liquid state, into said casting assembly; (c) allowing
said metal to cool and solidify; and (d) then separating the cast
metal part from said casting assembly.
17. A metal casting made by the process of claim 16.
18. A no-bake process for preparing a foundry shape comprising: (a)
introducing a major amount of the composition of claim 14 into a
pattern to form a shape; (b) allowing the shape to cure; and (c)
removing the shape from the pattern.
19. A process for casting a metal part comprising: (a) inserting a
foundry shape prepared in accordance with claim 18 into a casting
assembly having one or more molds and/or cores; (b) pouring metal,
while in the liquid state, into said casting assembly; (c) allowing
said metal to cool and solidify; and (d) then separating the cast
metal part from said casting assembly.
20. A metal casting made by the process of claim 19.
21. A heat cured process for preparing a foundry shape comprising:
(a) introducing a major amount of foundry mix comprising a (i)
refractory, (ii) a novolak resin and (iii) a polyisocyanate into a
heated pattern to form a foundry shape, wherein component (ii)
and/or component (iii) further comprise, as a solvent, one or more
cycloalkanes selected from the group consisting of unsubstituted
cycloalkanes, substituted cycloalkanes, and mixtures thereof; (b)
allowing the foundry shape to cure; and (c) removing the foundry
shape from the pattern when it is handleable.
Description
RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional Patent
Application Ser. No. 61/266,036 filed Jul. 16, 2009.
BACKGROUND
[0002] In the foundry industry, one of the procedures used for
making metal parts is "sand casting". In sand casting, disposable
foundry shapes, e.g. molds, cores, sleeves, pouring cups,
coverings, etc. are fabricated with a foundry mix that comprises a
mixture of a refractory (typically sand) and an organic or
inorganic binder.
[0003] Foundry shapes are typically made by the so-called no-bake,
cold-box processes, and/or heat cured processes. In the no-bake
process, a liquid curing catalyst is mixed with a refractory and
binder to form a foundry mix before shaping the mixture in a
pattern. The foundry sand mix is shaped by compacting it in a
pattern, and allowing it to cure until it is self-supporting. In
the cold-box process, a vaporous curing catalyst is passed through
a shaped mixture (usually in a corebox) of the aggregate and binder
to form a cured foundry shape. In the heat cured processes the
shape mixture is exposed to heat which activates the curing
catalyst to form the cured foundry shape.
[0004] There are many requirements for a binder system to work
effectively. For instance, the binder typically has a low
viscosity, must be gel-free, and remain stable under storage and
use conditions. In order to obtain high productivity in the
manufacturing of foundry shapes, binders are needed that cure
efficiently, so the foundry shapes become self-supporting and
handleable as soon as possible.
[0005] With respect to the no-bake and heat cured processes, there
must be adequate worktime to allow for the fabrication of larger
cores and molds. On the other hand, with respect to cold-box
processes, the shaped foundry mix must cure nearly instantaneously
upon contact with the vaporous curing catalyst. The foundry shapes
made with the foundry mixes using either no-bake, cold-box or heat
cured binders have adequate mechanical strengths, particularly
immediate tensile and transverse strengths, scratch hardness, and
exhibit resistance to ambient humidity.
[0006] One of the greatest challenges facing the formulator is to
formulate a binder that will hold the foundry shape together after
is made so it can be handled, stored and will not disintegrate
prematurely during the metal casting process, yet will allow for
acceptable mold and core removal properties upon cooling of the
solidified cast metal part, often referred to as shake-out. Without
this property, time consuming and labor intensive means must be
applied to break down the spent foundry shapes so the metal part
can be removed from the casting mold and core assembly. Another
related property required for an effective foundry binder is that
foundry shapes made with the binder must release readily from the
pattern in which they are created.
[0007] The flowability of a foundry mix made from a refractory and
an organic binder can pose greater problems with respect to
cold-box applications. This is because, in some cases, the
components of the binder, particularly the components of phenolic
urethane binders, may prematurely react after mixing with the
refractory sand, while they are waiting to be used. If this
premature reaction occurs, it will reduce the flowability of the
foundry mix and the molds and cores made from the binder will have
reduced mechanical strengths. This reduced flowability and decrease
in strength with time indicates that the "benchlife" of the foundry
mix is inadequate. If a binder results in a foundry mix without
adequate benchlife, the binder is of limited commercial value.
[0008] In view of all these requirements for a commercially
successful foundry binder, the pace of development in foundry
binder technology is gradual. It is not easy to develop a binder
that will satisfy all of the requirements of interest in a
cost-effective way.
[0009] Furthermore, besides excellent performance and cost
effectiveness, demands for the composition of the formulation may
exist because of environmental, health, and safety regulations and
concerns. Environmental concerns are particularly relevant today
because most of the foundry binders used commercially contain
significant amounts of aromatic hydrocarbon solvents, which in turn
may comprise compounds like benzene, toluene, xylene,
1,2,4-trimethylbenzene, naphthalene and other aromatic compounds
and fractions of concern. Recently, there has been increased
concern with using aromatic hydrocarbon solvents in foundry binders
and an interest in reducing the amount used or totally eliminating
their use prevails.
[0010] The prior art discloses that the reduction and possible
elimination of aromatic hydrocarbon solvents in foundry binder
systems based upon phenolic resole resins and polyisocyanates has
been explored several times. For instance, European Patent No.
0771569 describes replacing aromatic hydrocarbon solvents with
methyl esters of one or more fatty acids, with a carbon chain from
12 carbon atoms. Although the binders make useful cores and molds,
it has been found that smoke and acrid odors result during the
pouring, cooling and shakeout process, and that it is more
difficult to reclaim and reuse sand obtained from spent molds and
cores made with these binders. Consequently, in practice, there is
a tendency to use the fatty acid esters as a co-solvent in
combination with traditional aromatic hydrocarbon solvents.
[0011] More recently European patent 1057554 disclosed the use of
alkyl silicates, in particular, tetraethyl silicate, to replace
aromatic hydrocarbon solvents. This technology also has some
drawbacks, e.g. gel formation in the acidic scrubber solution used
for abating the amine curing gas and the formation of fine white
silica particles which may deposit on the cast part, accumulate in
the spent sand or become airborne.
[0012] Acyclic aliphatic solvents, for instance kerosene and
tetradecene have been used in small additions in
polyol-polyisocyanate binders, particularly phenolic urethane
cold-box and no-bake binders, but their strong non-polar solvency
properties have resulted in significantly limiting their amount in
the binder formulation to less than five weight percent in the
total binder, i.e. the combined weight of the Part I (polyol
component) and the Part II (polyisocyanate component).
[0013] In view of this background, there is a need to develop
foundry binders that contain no aromatic hydrocarbon solvents or
employ them at a much reduced level, while maintaining excellent
performance and cost effectiveness and adequate consideration for
environmental, health and safety concerns.
SUMMARY
[0014] This disclosure relates to foundry binders comprising (a) a
polyol component selected from the group consisting of phenolic
resins, polyether polyols, polyester polyols, aminopolyols, and
mixtures thereof, and (b) a polyisocyanate component, wherein
component (a) and/or (b) further comprise, as a solvent, one or
more cycloalkanes. The disclosure also relates to foundry mixes
prepared with the foundry binders, the cold-box, no-bake and heat
cured processes for making foundry shapes using the foundry mixes,
and processes for making cast metal parts using the foundry shapes
and the processes for metal casting.
[0015] There are environmental, health, and safety advantages of
using the binders according to the present invention because
aromatic hydrocarbon solvents comprising benzene, toluene, xylene,
1,2,4-trimethylbenzene, naphthalene and other aromatic compounds
and fractions can be eliminated or reduced when formulating the
foundry binders. As result, unwanted gases, fumes and odors are
reduced or eliminated when foundry shapes are made from foundry
mixes made with the binders according to the present invention and
when metal parts are cast using these foundry shapes. Furthermore,
there is no potential exposure to silica particles that exists when
alkyl silicates are used as solvents in foundry binders used for
making foundry shapes.
[0016] It is believed that the use of cycloalkanes as solvents in
the defined foundry binders, as a complete or partial replacement
for aromatic hydrocarbon solvents may: (1) reduce the amount of
photochemically active species that may have a deleterious effect
on the ozone layer and which are liberated when foundry shapes are
made with the binders and when the foundry shapes are used to make
metal parts in the course of the metal casting process; (2) reduce
the formation of tar-like materials in the venting system of
semi-permanent molds, a technology commonly used to make automotive
cylinder heads; (3) provide improvements in quality of the cast
metal parts made from the foundry shapes; (4) improve mold and core
quality by eliminating or reducing solvent build-up in attrition
reclaimed sand and green sand molding systems; and (5) reduce dense
smoke formation during pouring, cooling and shake-out.
[0017] Because it is known that binders based upon polyols and
polyisocyanates, particularly phenolic resole resins, are sensitive
to the various properties of the solvents, it was unexpectedly
found that cycloalkanes could be used to completely or partially
replace aromatic hydrocarbon solvents that are traditionally used
in such binders without adversely affecting the performance
characteristics of the binder with respect to product storage
stability and core and mold making performance. This was
particularly unexpected because it is known that acyclic aliphatic
solvents such as kerosene and tetradecene are not compatible with
phenolic resins and polyisocyanates at high levels, especially at a
level which would totally replace all aromatic hydrocarbon solvents
in the foundry binder.
DETAILED DESCRIPTION
[0018] It is preferred to package and use the binders system as a
two-part system.
[0019] The polyol component of the foundry binder (Part I)
comprises a polyol selected from the group consisting of phenolic
resins, polyether polyols, polyester polyols, amine polyols, and
mixtures thereof. Preferably used as the polyol are phenolic resole
resins.
[0020] The polyisocyanate component of the binder (Part II)
comprises a polyisocyanate selected from the group consisting of
aliphatic polyisocyanates and aromatic polyisocyanates and mixtures
thereof. Preferably used as the polyisocyanate because of its
availability is methylene diphenylisocyanate.
[0021] As was mentioned previously, the preferred polyol is a
phenolic resin, which is liquid or organic solvent-soluble. The
phenolic resin component of the binder composition is generally
employed as a solution in an organic solvent. The amount of solvent
used should be sufficient to result in a binder composition with
adequate viscosity permitting uniform coating thereof on the
aggregate and uniform reaction with the polyisocyanate component in
the foundry sand mix. The specific solvent concentration for the
phenolic resin 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
polyol component, typically in the range of 20% to 80% by weight of
the polyol component.
[0022] A phenolic resole resin is preferably prepared by reacting a
molar 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.
[0023] The phenol used to prepare the phenolic resole resins
include phenol itself and/or 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. Such unsubstituted
positions are necessary for the polymerization reaction. Any one,
all, or none 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, cycloalkyl-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.
[0024] Alternatively, novolak resins may be used. Bisphenol F is
the simplest novolak and is prepared by reacting a large molar
excess of phenol with formaldehyde under acidic conditions, which
results in an isomer mixture comprising o,p' isomers, p,p' isomers
and o,o' isomers. A typical acid catalyst is oxalic acid.
[0025] Specific examples of suitable phenols include phenol,
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 4,4'-diphenol and bisphenol A are
also suitable.
[0026] The aldehyde used to react with the phenol has the formula
RCHO wherein R is a hydrogen or a 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, benzaldehyde and the like, and mixtures thereof.
The most preferred aldehyde is formaldehyde.
[0027] Polyether polyols are commercially available and their
method of preparation and determining their hydroxyl value is well
known. The polyether polyols are prepared by reacting an alkylene
oxide with a polyhydric alcohol in the presence of an appropriate
catalyst such as sodium methoxide according to methods well known
in the art. Any suitable alkylene oxide or mixtures of alkylene
oxides may be reacted with the polyhydric alcohol to prepare the
polyether polyols. The alkylene oxides used to prepare the
polyether polyols typically have from two to six carbon atoms.
Representative examples include ethylene oxide, propylene oxide,
butylene oxide, amylone oxide, styrene oxide, or mixtures thereof.
The polyhydric alcohols typically used to prepare the polyether
polyols generally have a hydroxy functionality greater than 2.0,
preferably from 2.5 to 5.0, most preferably from 2.5 to 4.5.
Examples include ethylene glycol, diethylene glycol, propylene
glycol, trimethylol propane, glycerine, and tetramethylol
methane.
[0028] Aminopolyols are also well known and are described in U.S.
Pat. No. 4,448,907, and are normally produced as the reaction
product of an alkylene oxide and an amine compound. In general, any
polyol containing at least one or more tertiary amine groups are
considered to be within the scope of the definition of
"aminopolyol". The alkylene oxides which are used to prepare the
amine polyols are preferably ethylene oxide and propylene oxide.
However, it appears feasible to use other alkylene oxides as well.
The amine compounds which react with an alkylene oxide to yield the
aminopolyol useful in the binder composition constituting this
invention include ammonia and mono and polyamino compounds with
primary or secondary amine groups. Specific examples include
aliphatic amines such as primary alkyl amines, ethylene diamine,
diethylene triamine and triethylene tetramine, cycloaliphatic
amines such as cyclohexyl amine, pyrrolidine, morpholine and
N,N'-diethylene diamine, aromatic amines, such as aniline, ortho-,
meta-, and para-phenylene diamines, aniline-formaldehyde resins and
the like. The aminopolyols typically have a hydroxyl number of from
about 200 to 1000 mg/g KOH, preferably from about 600 to 800 mg/g
KOH.
[0029] Polyester polyols that can be used are aliphatic and/or
aromatic polyester polyols. Preferred polyester polyols are blends
of liquid aromatic polyester polyols, which typically have a
hydroxyl number from about 200 to 2,000 mg/g KOH, preferably from
200 to 1200 mg/g KOH, and most preferably from 250 to 800 mg/g KOH;
a functionality equal to or greater than 2.0, preferably from 2 to
4; and a viscosity of 500 to 50,000 centipoise at 25.degree. C.,
preferably 1,000 to 35,000 centipoise, and most preferably 1,500 to
25,000 centipoise. Aromatic polyester polyols are typically
prepared by ester interchange of aromatic ester and alcohols or
glycols by an acidic catalyst. Phthalates are typically used as
aromatic esters to make aromatic polyester polyols. Examples of
alcohols used to prepare the aromatic polyester polyols are
ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propane
diol, 1,4-butane diol, dipropylene glycol, tripropylene glycol,
tetraethylene glycol, trimethylol propane, tetramethylol methane,
glycerin, and mixtures thereof. Aliphatic polyester polyols are
typically made by direct condensation of the acid with the alcohol.
Examples of acids used to prepare the aliphatic polyester polyols
are succinic acid, glutaric acid, adipic acid, citric acid,
tertrahydrophthalic acid, and mixtures thereof. Examples of
alcohols used to prepare the aliphatic polyester polyols are
ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propane
diol, 1,4-butane diol, dipropylene glycol, tripropylene glycol,
tetraethylene glycol, trimethylol propane, tetramethylol methane,
glycerin, and mixtures thereof.
[0030] Any organic polyisocyanate can be used in the Part II, the
polyisocyanate component. The polyisocyanate component of the
binder composition is generally employed as a solution in an
organic solvent, but binders can be used in which the Part II
consists of 100% polyisocyanate. The specific solvent concentration
in the polyisocyanate component will vary depending on the type of
phenolic resins employed in the Part I and its molecular weight. In
general, the solvent concentration will be in the range of up to
80% by weight of the polyisocyanate component, typically in the
range of up to 50%.
[0031] Examples of organic polyisocyanates used include
polyisocyanates having a functionality of two or more, preferably 2
to 5. It may be aliphatic, cycloaliphatic, aromatic, or a hybrid
polyisocyanate, or mixtures thereof. Representative examples of
polyisocyanates are aliphatic polyisocyanates such as hexamethylene
diisocyanate and 1,12-diisocyanatododecane, alicyclic
polyisocyanates such as 4,4'-dicyclohexylmethane diisocyanate and
isophorone diisocyanate, and aromatic polyisocyanates such as
methylene diphenylisocyanate and its isomers and polymeric
varieties, 2,6-toluene diisocyanate, and derivatives thereof. Other
examples of suitable organic polyisocyanates are 1,5-naphthalene
diisocyanate, triphenylmethane triisocyanate, xylylene
diisocyanate, and derivatives thereof, and the like. Also, it is
contemplated that chemically modified polyisocyanates, prepolymers
of polyisocyanates, and quasi prepolymers of polyisocyanates can be
used. 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, typically in
the range of up to 50%.
[0032] The polyisocyanates are used in sufficient concentrations to
cause the curing of the phenolic resin when catalyzed with a
tertiary amine curing catalyst. In general the isocyanato group
ratio of the polyisocyanate component to the hydroxyl groups of the
polyol component is from 1.25:1 to 1:1.25, preferably about
1:1.
[0033] The Part I and/or the Part II of the binder contain one or
more cycloalkanes as a solvent. The cycloalkanes are selected from
the group consisting of unsubstituted cycloalkanes, substituted
cycloalkanes, and mixtures thereof. Preferably, the number of
carbon atoms in the cycloalkane is from 5 to 24, the number of
rings, including individual fused, bridged, and spiro-connected
ring arrangements in the cycloalkanes is from 1 to 4, and the
number of carbon atoms in the individual rings of bi-, tri-, and
tetracyclic cycloalkanes is from 3 to 10, preferably from 5 to 8.
Examples of cycloalkanes that can be used as solvents in the Part I
and/or Part II of the binder include, but are not limited to,
cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane,
cyclodecane, norcarane, norpinane, norbornane, decahydroazulene,
tricycle[2.2.1.0]hexane, tetracyclo[5,2,2,0,0]undecane,
spiro[4.5]decane, dispiro[5.1.7.2]heptadecane,
decahydronaphthalene, bicyclohexyl, tercyclodecane,
1-cyclobutyl-2-cyclopentylethane, perhydroantharacene,
perhydrofluorene, their partially unsaturated congeners, alkyl,
alkenyl and alkynyl derivatives, and mixtures thereof. Typically,
the cycloalkane that will be used is decahydronaphthalene because
it is the most readily and abundantly available cycloalkane.
[0034] The foundry binder may contain other solvents. In
particular, the foundry binder may further comprise one or more
solvents selected from the group consisting of aromatic hydrocarbon
solvents, dibasic ester solvents, fatty acid ester solvents, and
mixtures thereof, which may be formulated in the Part I, Part II,
or both the Part I and Part II of the foundry binder.
[0035] The total amount of solvents in the binder typically ranges
from 1 to 80 parts by weight based upon 100 parts by weight of the
binder, preferably from 5 to 60 parts by weight based upon 100
parts by weight of the binder, and most preferably from 15 to 50
parts by weight based upon 100 parts by weight of the binder.
[0036] The total amount of cycloalkane in the binder typically
ranges from 5 to 40 parts by weight based upon 100 parts by weight
of the binder, preferably from 5 to 30 parts by weight based upon
100 parts by weight of the binder, and most preferably from 5 to 20
parts by weight based upon 100 parts by weight of the binder.
[0037] If the cylcoalkane is used in the Part I of the binder, the
total amount of cycloalkane used in the Part I ranges from 0 to 30
parts by weight based upon 100 parts by weight of the Part I,
preferably from 5 to 25 parts by weight based upon 100 parts by
weight of the Part I, and most preferably from 5 to 20 parts by
weight based upon 100 parts by weight of the Part I.
[0038] If the cylcoalkane is used in the Part II of the binder, the
total amount of cycloalkane used in the Part II typically ranges
from 0 to 60 parts by weight based upon 100 parts by weight of the
Part II, preferably from 5 to 40 parts by weight based upon 100
parts by weight of the Part II, and most preferably from 5 to 30
parts by weight based upon 100 parts by weight of the Part II.
[0039] Foundry mixes are prepared by mixing a foundry refractory
with the foundry binder. Various types of refractories and amounts
of binder are used to prepare foundry sand 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 refractory. The amount of binder and the type of
refractory used are known to those skilled in the art. The
preferred refractory employed for preparing foundry mixes is silica
sand wherein at least about 70 weight percent, and preferably at
least about 85 weight percent, of the sand is silica. Other
suitable refractory materials for ordinary foundry shapes include
zircon, olivine, aluminosilicate, chromite, and the like.
[0040] In typical 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 refractory. Most often, the binder content for ordinary
foundry shapes ranges from about 0.6% to about 5% by weight based
upon the weight of the refractory.
[0041] The binder compositions are preferably made available as a
two-part system with the polyol component in one part (Part I) and
the polyisocyanate component as the other part (Part II). Usually,
the polyol is first mixed with the refractory and then the
polyisocyanate component is added, but the order of addition can be
reversed. Methods of distributing the binder onto the refractory
particles are well-known to those skilled in the art.
[0042] It will be apparent to those skilled in the art that other
additives such as coupling agents, flow enhancers, benchlife
extenders, release agents, drying agents, defoamers, wetting
agents, etc. can be added to the binder, refractory, or foundry
mix. The particular additives chosen will depend upon the specific
purposes of the formulator.
[0043] In general, metal parts are made by creating a mold assembly
with an internal cavity shaped to match the dimensions and profile
of the metal part to be cast and a gating system to feed the hot
liquid metal into the cavity. Molds and/or cores are inserted are
inserted into the mold assembly to produce external and internal
casting geometry that will shape the metal part when molten metal
is poured into the mold assembly and cools. Optionally, a
refractory coating can be applied to all or select components of
the mold assembly that come in contact with the liquid metal.
[0044] Foundry shapes are prepared by a cold-box process
comprising:
[0045] (a) introducing a major amount of a foundry mix into a
pattern to form a foundry shape;
[0046] (b) contacting the foundry mix in the pattern with a
vaporous curing catalyst;
[0047] (c) allowing the foundry shape to cure; and
[0048] (d) removing the foundry shape from the pattern when it is
handleable.
[0049] Curing of polyol-polyisocyanate binders by the cold-box
process is carried out by contacting the foundry shape with the
vapor of a volatile tertiary amine as described in U.S. Pat. No.
3,409,579, which is hereby incorporated into this disclosure by
reference. Examples of volatile tertiary amines, which can be used,
include trimethylamine, dimethylethylamine, triethylamine,
dimethylpropylamine, and the like.
[0050] Foundry shapes are prepared by a no-bake process
comprising:
[0051] (e) introducing a major amount of foundry mix containing a
liquid curing catalyst into a pattern to form a foundry shape;
[0052] (f) allowing the foundry shape to cure; and
[0053] (g) removing the foundry shape from the pattern when it is
handleable.
[0054] The preferred liquid curing catalyst for the
polyol-polyisocyanate binders is a tertiary amine and the preferred
no-bake curing process is described in U.S. Pat. No. 3,485,797
which is hereby incorporated by reference into this disclosure.
Specific examples of such liquid curing catalysts are amines which
have a pK.sub.b value generally in the range from about 5 to about
11 and include 4-alkyl pyridines wherein the alkyl group has from
one to four carbon atoms, for instance 4-phenylpropylpyridine,
isoquinoline, arylpyridines such as phenyl pyridine, pyridine,
acridine, 2-methoxypyridine, pyridazine, 3-chloro pyridine,
quinoline, N-methyl imidazole, N-ethyl imidazole, N-vinyl
imidazole, 4,4'-dipyridine, 1-methylbenzimidazole, 1,4-thiazine and
(3-dimethylamino)propylamine.
[0055] Foundry shapes are prepared by a heat cured process
comprising:
[0056] (h) introducing a major amount of foundry mix containing an
refractory, a novolak resin and a polyisocyanate into a heated
pattern to form a foundry shape;
[0057] (i) allowing the foundry shape to cure; and
[0058] (j) removing the foundry shape from the pattern when it is
handleable.
[0059] The heat curing process is described in WO 2004050738 which
is hereby incorporated by reference into this disclosure.
[0060] Metal parts are prepared by a process for casting a metal
part comprising:
[0061] (k) inserting a foundry shape into a casting assembly having
one or more molds and/or cores;
[0062] (l) pouring metal, while in the liquid state, into said
casting assembly;
[0063] (m)allowing said metal to cool and solidify; and
[0064] (n) then separating the cast metal part from said casting
assembly.
[0065] The metal parts can be cast from ferrous metals such as grey
and white iron, ductile iron, compacted graphite iron and steel,
and nonferrous metals such as aluminum, magnesium, copper, zinc,
titanium and alloys thereof. The temperature of the molten ferrous
metal ranges from about 1100.degree. C. to about 1700.degree. C.
The temperature of the molten nonferrous metal ranges from about
400.degree. C. to about 1700.degree. C.
[0066] The term "comprising" (and its grammatical variations) as
used herein is used in the inclusive sense of "having" or
"including" and not in the exclusive sense of "consisting only of."
The terms "a" and "the" as used herein are understood to encompass
the plural as well as the singular.
EXAMPLES
Examples A, B, 1, and 2
[0067] Test foundry cores were made with by the cold-box process by
first mixing Congleton HST 50 silica sand (from WBB minerals,
Sibelco UK Ltd.) with the binder formulations described in Table I
in a Kenwood Chef mixer for one minute. The phenolic resole resin
(RESIN) used in the Part I of the binder was a polybenzylic ether
phenolic resin prepared with zinc acetate dihydrate as the catalyst
according to methods well-known in the art. The polyisocyanate used
in the Part II of the binder was poly(rnethylene
diphenylisocyanate) having a functionality of 2.7. Equal amounts of
Part I and Part II were employed and the amount of the total binder
used was 1.2 weight percent based on the weight of the sand.
[0068] The resulting foundry mixes were compacted into a cavity to
produce test cores having dimensions of
120mm.times.22.4mm.times.6mm by blowing the foundry sand mix into a
metal pattern where they were cured by the cold-box process as
described in U.S. Pat. No. 3,409,579. The test cores were contacted
with a mixture of triethylamine (0.25 ml) in nitrogen at a pressure
of 1.4 bar for 1 second, followed by purging with nitrogen at a
pressure of 4 bar for about 18 seconds, thereby forming the test
specimen.
[0069] No objectionable odor was noticed when binders were prepared
and the test cores were prepared.
[0070] Unless otherwise indicated, the test cores were made with a
freshly prepared foundry sand mix and the transverse strength was
measured 30 seconds, 3 minutes, and 6 minutes after the specimen
was formed. Measuring the transverse strength of the test cores
enables one to predict how the mixture of sand and binder will work
in actual foundry operations. Lower transverse strengths for the
shapes indicate that the phenolic resin and polyisocyanate reacted
more extensively during and after mixing with the sand and prior to
curing.
[0071] Examples A and B are comparison examples and do not contain
any cycloalkane, while Example 1 is within the scope of this
invention.
TABLE-US-00001 TABLE I (Binder formulations and transverse
strengths of test cores made with binders) EXAMPLE A B 1 Part I
RESIN 64 65 69 DBE.sup.1 18 18 AHS.sup.2 34 FAE.sup.3 15 DHN.sup.4
11 Part II MDI 75 75 85 AHS 25 25 DHN 15 Transverse
Strength(KPa).sup.5 30 seconds 1986 1880 1739 3 minutes 2616 2223
2244 6 minutes 3042 2588 2273 .sup.1Dibasic ester solvent
.sup.2Aromatic hydrocarbon solvent .sup.3Fatty acid ester solvent
.sup.4Decahydronaphthalene .sup.5Kilopascals
[0072] The data in Table I suggest that the transverse strengths of
test cores made with the binder containing decahydronaphthalene
(DHN) compare favorably to transverse strengths of test cores made
with a commercially available phenolic urethane cold-box binder
based on a typical aromatic hydrocarbon solvent (AHS) system and
one based on fatty acid ester (FAE) and dibasic ester (DBE)
solvents.
[0073] All publications, patents and patent applications cited in
this specification are herein incorporated by reference, and for
any and all purposes, as if each individual publication, patent or
patent application were specifically and individually indicated to
be incorporated by reference. In the case of inconsistencies, the
present disclosure will prevail.
[0074] The foregoing description of the disclosure illustrates and
describes the present disclosure. Additionally, the disclosure
shows and describes only the preferred embodiments but, as
mentioned above, it is to be understood that the disclosure is
capable of use in various other combinations, modifications, and
environments and is capable of changes or modifications within the
scope of the concept as expressed herein, commensurate with the
above teachings and/or the skill or knowledge of the relevant
art.
[0075] The embodiments described hereinabove are further intended
to explain best modes known of practicing it and to enable others
skilled in the art to utilize the disclosure in such, or other,
embodiments and with the various modifications required by the
particular applications or uses. Accordingly, the description is
not intended to limit it to the form disclosed herein. Also, it is
intended that the appended claims be construed to include
alternative embodiments.
* * * * *