Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relate~ to compositions of
matter and methods of using said compositions. More parti-
cularly, it relates to compositions of matter useful as
mold release and parting agents for protecting and lubricat-
ing the surfaces of molds, plungers, and other article-
forming parts, especially such as are useful in the manu-
facture, forming, and handling of glass articles or the
lik- at high temperatures.
Before 9ituating new molds into use, the glass
industry has generally adapted the process of using various
compositions applied to the mold-forming surfaces. ,While
these compositions and methods of application have been
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successful as a preliminary treatment, many difficulties
have been observed in the subsequent treatment of the molds
~15 during operation in the molding machines.
In glass manufacturing, a glob of molten glass is
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formed by a blank mold into a finished portion corresponding
to the neck portion of the desired glass article. It is a
requirement that the molding surface of the blank mold not
20 `~ become abraded or pitted so that the molten glass will readily
flow over the molding surface of the mold, take the shape
thereof, and then separate therefrom. As can be appreciated,
this process creates a dragging or abrasive effect upon the
m~lding surface of the glass-forming equipment. While the
working temperatures of the glass-forming machine may vary
from about 500 to 1000F., in the glass industry, it often
i
~ reaches 1200F. Generally, during the final process of
;~ ~shaping and forming, the molten glass is heated to a tempera-
ture between about 1250F., to 1350F. Therefore, any molds
and release compositions must be compatible with and effective
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at these temperatures.
Several practices have been followed in the past
for the protection and lubrication of such molds used in
forming glass articles. The common practice in most cases
in the glass factories has been to use for this purpose a
compound of bulk of which consists of light paraffin base
oil and containing graphite in suspension. These light
paraffin base oils are numerous in kinds and such hydro-
carbons as kerosene have been employed. Generally, these
compositions are applied by spraying, painting, or swabbing
during the forming operation so as to provide lubrication of
the interacting mold sections to prevent sticking of the
molten glass to the mold surfaces. While a spray of oil
carrying the lubricant such as graphite may be used at these
temperatures r there are many important objections to the
use of the light paraf~in base oil. It is used primarily as
a carrier for the graphite and quickly volatilizes on the
hot surfaces of the molds. Thus, it will be appreciated
that this presents drawbacks in such compositions containing
these oils as well as their method of application. Aside
from the obnoxious odors, the vaporized materials create
considerable volumes of smoke which reduce visibility, and
produce upon condensation serious fire hazards which often-
times become progressively worse as the accumulation in-
creases. Further, as a result of the evaporation of so muchoil from the glass~forming surfaces, there is a tendency for
hard carbon deposits to build up on such mold surfaces thus
producing inferior glassware and even more serious troubles.
It should be added that the storage of the necessary sub-
stantial quantities of oil is a nuisance in a glass factory
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and of course the cost of the oil i5 a considerable item.The application of these conventional compositions to various
moving parts of the machine in actual production must be
regularly repeated a number of times on a periodic basis
which, could result in injury to operators. Needless to say,
these problems have required that the industry employ other
solutions to circumvent these undesirable conditions.
Because of these objections to the use of paraf-
finic materials various attempts have been made to use a
solution or suspension of a lubricant in an aqueous system.
A number of aqueous systems have been employed with various
degrees of success. While such a solution is useful in the
preliminary treatment where the application is made at temper-
atures substantially lower than 500F., it has not been
lS found satisfactory for use during subsequent treatment where
the mold temperature is necessarily higher, usually over
825F. This is due to the fact that the small drops of
water striking the hot surfaces are converted into steam with
almost explosive violence, carrying with it mechanically the
lubricant which has been in solution or suspension in the
water. Thus, instead of adhering the mold surface, most of
the lubricant falls away and is wasted. The use of various
binders which resolve this problem by fusing and bonding the
lubricant to the mold~orming surface have been suggested.
Because of the rigorous operating conditions and high temper-
atures encountered in glass-forming operations, numerous
compositions employing lubricants in conjunction with various
binders have only been moderately utilized by those skilled
in the art. The subject invention deals with one approach
for precoating molds and molding parts with an aqueous
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dispersion, especially applicable to the glass~forming
machines.
One departure which the subject invention comtemp-
lates from prior attempts is to explore thermally stable
lubricants in conjunction with various carriers which
offer a release and lubricating composition that can
readily adhere to very hot working surfaces and be
utilized over prolonged periods of time with only minor
recharging.
After investigation, we have found compositions
of matter which are advantageous in several respects
over the prior art compositions, particularly in their
capacity to hold up under long periods of time and under
a wide range of severe commercial operating conditions.
The features and advantayes of the present invention
will be come apparent from the following description.
This invention relates to a release and lubricating
composition comprising an aqueous dispersion of a mixture
of tungsten disulfide having a lamellar-hexagonal
crystalline structure, said tungsten disulfide having
an average particle size of less than 2 microns, a
silicate, a setting agent, and, where required, carbon
or graphite having a particle size within the range of
abou' 10 to 200 microns.
This invention further relates to a release and
lubricating composition comprising an aqueous dispersion
of a mixture of tungsten disulfide having a lamellar-
hexagonal crystalline structure, said tungsten disulfide
having
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~ '..,~
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an average particle size of less than 2 microns, an alkali metal silicate,
and a setting agent selected from the group consisting of zinc oxide, calcium
chloride, magnesium sulfate, aluminum sulfate, sodium borate, sodium meta-
borate, sodium fluorosilicate, kaolinitic clays and minerals and mixtures
thereof, and, from 0 to 50 weight percent, carbon or graphite having a
particle size within the range of about 10 to about 200 microns.
This invention further relates to a release and lubricating com-
position comprising an aqueous dispersion of a mixture of about 25 to about
70 weight percent tungsten disulfide, having a lamellar~hexagonal crystalline
structure, said tungsten disulfide having an average particle size of less
than 2 microns, from about 15 to about 25 weight percent of a silicate, from
about 1 to about 10 weight percent of a setting agent, and, from 0 to 50
weight percent carbon or graphite having a particle size within the range of
about 10 to about 200 microns.
This invention further relates to a release and lubricating com-
position comprising an aqueous dispersion of a mixture of about 25 to about
70 weight percent tungsten disulfide having a lamellar-hexagonal crystalline
structure, said tungsten disulfide having an average particle size of less
than 2 microns, from 0 to about 50 weight percent of graphite having an
average particle size of less than 200 microns from about 15 to about 25
weight percent of an alkali metal silicate, and from about 1 to about 10
weight percent of a setting agent selected from the group consisting of zinc
oxide, calcium chloride, magnesium sulfate, aluminum sulfate, sodium borate,
sodium metaborate, sodium fluorosilicate, kaolinitic clays and minerals, and
mixtures thereof.
This invention further relates to a method of forming a lubricating
and release coating on surfaces of molds and related parts, comprising: l
applying an aqueous dispersion of a mixture of tungsten disulfide having a
lamellar-hexagonal crystalline structure, said tungsten disulfide having
an average particle size of less than 2 microns, a silicate, a setting agent,
C ~ - 5a -
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and, from 0 to 50 weight percent carbon or graphite having a particle size
within the range of about 10 to about 200 microns; and removing the water
to affix the silicate to the surfaces to form a thin coating thereon.
This invention further relates to a method of forming a lubricating
and release coating on surfaces of molds and related parts, comprising:
applying a dispersion of a mixture of tungsten disulfide having a lamallar-
hexagonal crystalline structure, said tungsten disulfide having an average
particle size of less than 2 microns, an alkali metal silicate, a setting
agent, and, from 0 to 50 weight percent carbon or graphite having a particle
size within the range of about 10 to about 200 microns, to the molds and
related parts to be coated; heating said molds and parts to affix the silicate
to the sruface to form a thin coating thereon.
This invention further relates to a method of molding a glass
article, comprising: treating the surfaces of a mold and related parts that
come in contact with a hot glass body with a composition comprising an
aqueous dispersion of a mixture of tungsten disulfides, a silicate, a setting
agent, and, from 0 to 50 weight percent carbon or graphite having a particle
size within the range of about 10 to about 200 microns; heating the surface
and the dispersion to remove the water to form a coating on said surfaces;
contacting the coated surfaces with the hot glass body; and shaping said
body to a final form.
This invention further relates to a treated metal surface com-
prising a molding surface having securely adhered thereto a coating com-
prising tungsten disulfide, a silicate, a setting agent, and, where required,
carbon or graphite having a particle size within the range of about 10 to
about 200 microns, dispersed through the mixture, said coating being of a
thickness between 0.0004 to about 0.005 inch.
By the term "dispersion" as used herein, it is meant a system of
minute solid particles relatively distinct from one another and generally
suspended in a ~luid or liquid
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medium. This dispersion may be either in highly liquid form
or a highly viscous or paste-like form.
In accordance with this invention the tungsten
disulfide is present in finely divided state. Generally, a
particle size smaller than 2 microns is very suitable for the
compositions herein disclosed. The tungsten disulfide herein
employed should have a lamellar-hexagonal crystalline struc-
ture.
Tungsten disulfide exhibits a low coefficient of
friction averaging between about 0.025 to about 0.060, and
offers excellent release characteristics along with thermal
stability.
During its use on molds and surfaces thereof, it
is believed that the tungsten disulfide partially forms
tungsten oxides at about 900F., which seemingly also enhance
and provide low friction and release properties.
In accordance with this invention, the tungsten
disulfide may be readily admixed with graphite or carbon.
~he graphite or carbon used may be any of the various carbon
blacks, flake, and colloidal graphite or conventional graphite
known to the trade. Further, it is understood that either
natural or synthetic forms of graphite can be satisfactorily
employed in accordance with the present invention. The car-
bon or graphite may be of technical or spectro grade which
may be ball milled, if need be, to reduce particle size. The
particle size may range from between about 10 to 200 microns.
Preferrably, the particle size may range from about 75 mic-
rons or less. Based on the weight of the total composition,
the weight of tungsten disulfide may range from 30 to about
70 percent, whereas the amount of graphite may vary. m e
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amount of graphite may be from 0 to about 50 weight percent.
Aside from the lubricity it is believed that the tungsten
disulfide inhibits the oxidation of any carbon or graphite
which is added to the compositions herein to provide lub-
ricity and glass release.
The silicates used in the process and compositions
of this invention are those silicates generally of inorganic
bases. Exemplary of such silicates are sodium silicate,
potassium silicate, and lithium silicate. The preferred
inorganic silicate is sodium silicate since this silicate is
less expensive than potassium silicate. However, the organic
silicates may be satisfactorily employed and include guanidine
silicate, tetramethylammonium silicate, and tetraethanol~
ammonium silicate.
~he amount of silicate utilized in accordance with
this invention is that sufficient to bind the particles of
tungsten disulfide so that they are bonded to each other and
the metal substrate.
The best range for sodium silicate solutions is
that is which the SiO2/Na2O ratio by weight is 1.0 to 2.5,
and the best range for potassium silicate solutions is that
in which the SiOz/K2O ratio by weight is 1.0 to about 3Ø
Silicates of strong bases are readily available from commer-
cial sources. All such commercially available-silicates are
useful in preparing and applying the compositions herein
described.
, The setting agents employed herein denote certain
compounds that greatly enhance,the usefulness of the subject
invention. Although the setting agents seemingly function
as curing ag~nts for the silicates, they apparently also
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function as buffers to allow water of crys~alization to
gradually leave a coatecl surface upon drying or removal of
the aqueous material. ~'he setting agent seemingly serves to
tie up any water momentarily so that there is no burst of
steam or bubbling on the surface. In this regard, it is
understood that the setting agent herein described enhance
the silicates of this invention, although it is only hypo-
thesized as to their specific functional characteristics.
The amount of these setting agents may range from about 1
to about 10 weight percent of the total aqueous dispersion.
In general, setting agents are acidic or heavy
metal compounds, which seemingly react with the silicate
causing a gradual removal of water. The setting agents used
in the subject invention include zinc oxide, calcium chloride,
magnesium sulfate, aluminum sulfate, sodium borate, sodium
metaborate and sodium fluorosilicate. Also an effective
setting agent includes the kaolinitic clays and minerals
which heat-decompose into acidic compounds. These setting
agents may be readily admixed with the silicates of this
invention by any of the conventional methods known to the
art.
In carrying out the process of this invention, it
is generally desirable to clean the surface of the glass
forming equipment before hand to remove all contamination
such as metal oxides, loose particles, oil, dirt, and the
like to assure a better adhesion and longer life of the
coating.
In treating molds and mold parts with the compo-
sitions herein, their application and subsequent drying may
be carried out in a straightforward manner. Simply, the
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treatment of a mold or mold part consists in applying a
dispersion described herein and allowing the water to be
evaporated or removed by gentle heating or baking the parti-
cular coated part. A preferred method is to apply the coat-
ing compositions of this invention and air dry the same until
the water i8 substantially removed. Thereafter the coating
is ubjected to a higher temperature to remove any residual
water. It is understood that water in the aqueous disper-
sion may be removed by any number of conventional means.
After a uniform and smooth, thin coating is produced on the
metal surface, the mold is preferrably gently heated or baked
at a low temperature to drive off the water and thereafter
at an elevated temperature to affix and bond the tungsten
disulfide to the mold surface.
Subjecting the compositions herein to temperatures
between about 100F., to about 300F., generally for a
period of 30 minutes to 1 hour serves to adequately remove
the water during the initial period of heating. Thereafter,
heating at slightly increased temperature, that is between
,
about 300F., to about 700F., for a period of about several
minutes to about 2 hours serves to set the binder and remove
any traces of water or any other volatile constitutents.
Since glassware molds often must be preheated to an elevated
tempe~ature prior to installation and use on glassware-
producing machines, it is convenient to utilize the preheat-
ing period for the higher baking period.
The dispersion or mixtures of the subject inven-
tion may be applied to the mold or mold part by any of the
conventional means such as brushing, spraying, dipping, or
blowing onto the surface. Spraying is preferred.
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After affixing the release and lubricating com-
position herein disclosed, the composition adheres tenaciously
to the mold in a thin, uniform coating of silicate and tung-
sten disulfide. Although the coating is generally of micro-
scopic thickness, coating thicknesses may vary considerablydepending upon the amount applied and may range between about
0.0004 and 0.005 inch. It is preferred that there be between
about 0.0006 and 0.002 inch of coating material. The coating
itself is thermally stable, offers good oxidation resistance
and allows for adequate heat transfer. As regards lubricity,
it has been demonstrated that the compositions of the subject
invention render high temperature lubricity to a given sur-
face, that is, lubricity is particularly noted at temperatures
from between about 600 to 1700F.
While the heating operation serves to drive off
any water or other volatile constituents, it also sets th0
silicate and stabilizes the tungsten disulfide particles upon
the surface of the mold with the result that a firmly ad-
herent coating is produced. Again, because of the firm ad-
herence and durability of the coating obtained in the fore-
going manner, it is intregally bonded to the mold as compared
to the many superficial mold coating of the prior art.
It is often found that wetting agents be used in
conjunction with the foregoing compositions. Wetting agents
may be readily employed to facilitate dispersion of any of
the water-in~oluble ingredients such as tungsten disulfide
~` and graphite and to stabilize the resulting dispersion. A
wide range of wetting agents are available and any of the
conventional wetting agent~ may be utilized in conjunction
with the subject invention. Further, thickening agents and
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the like may also be employed to achieve a desired fluidity,
and pigments or fillers such as silicate, talc and diatoma-
ceous earth may be included, if desired, in order to facili-
tate complete covering of the desired mold surface by making
the coating readily visible to the operator as it is applied.
Also, additive constituents which may advantage-
ously, but optionally, included are compounds known to im-
prove oxidation resistance of the composition, thermal
stability and/or conductivity of the composition and wear
resistance thereof. Useful additives of this category in-
clude barium fluoride, silicon fluoride, zinc phosphate,
boron carbide, and calcium fluoride.
The results obtained through use of the afore-
described compositions demonstrate that the ordinary opera-
tional life on conventional machines is many times greaterthan the operational life of other coatings. Further, by
the composition herein disclosed and claimed, there is pro-
duced great savings in time and cost, since it is now pos~
sible to operate a glass-forming and handling equipment for
considerably longer periods of operational time, as well as
; to appreciatively minimize the necessity of hand swabbing
the molding equipment as extensively as before.
Although the present formulations and methods are
adaressed particularly to glass-forming machines and associ-
ated parts, it will be appreciated that such compositionsand methods are also very useful for other molds when parting
and lubrication are necessary. Thus, the herein described
compositions may be useful for metal forming industry, such
as for zinc, aluminum, etc. Also, said compositions may be
useful for molds for forming elastomers, rubber articles,
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plastics, etc.
The following Examples are offered to illustrate
the invention in more detail.
E X A M P L E
A conventional cast iron blank mold employed in
; molding 12 oz., glass bottles was cleaned by preheating to
about 700F., to remove any residual organic materials,
such as oils, etc. The surface o~ the blank mold was then
lightly sand-blasted to remove any residual scale, rust, or
other foreign materials therefrom.
A coating material was prepared by mixing 1,610
grams tungsten disulfide having a lamellar-hexagonal crys-
talline structure, and an average particle size of about
0.6 microns with 805 grams graphite having an average particle
size of about 70 microns. This mixture of lubricants was
introduced into l,400 grams of water lnto which was placed
24 grams of a sulfonate of oleic acid. Into this slurry
was placed about 1,614 grams of sodium silicate having a
SiO2/Na2O ratio of 2.40 and a 52 Baume at 68F., and mixed
with about lO00 grams of water! introduced into a ball mill
and mixed therein for approximately 3 hours. This formula-
; tion produced about 15 lbs., of coating material which has
a viscosity of about 5 seconds as determined by a No. 5 Zahn
cup vibcometer.
The mixture was sprayed by a spray gun over the
complete sandblasted surface of the prepared mold. The
coating was allowed to be air dried at room temperature for
about 30 minutes. Thereafter, the sprayed mold was cured
for 45 minutes at 500F., in an air circulating oven. The
treated mold was removed and installed in a conventional
12
lOS880~7
glass forming machine. The thickness of the caating after
spraying and allowing to air dry was about 0.0015 inch.
The blank mold treated in accordance with this
invention was used to produce a standard 12 oz., bottle
without additional swabbing. The coated mold formed over
15,000 bottles and performed satisfactory for at least 24
hours with no supplementary lubrication. It was noted that
the bottles produced by the use of this mold mix formed
bottles of uniform wall thickness. Further, there were
observed no "carbon marks" upon the surfaces of the bottles
produced. The bottles produced where of excellent quality.
E X A M P L E II
The precoated molds and related parts as prepared
in Example I were swabbed with a conventional petroleum-
based graphite compound (about 2% graphite and 98~ oil) atintervals from 45 and 60 minutes to produce some 45,000
bottles over a 72 hour period.
At the same rate of production, another mold
and related parts were employed to produce bottles, the
molds and related parts of this run not being treated by
precoating. These uncoated molds and related parts required
swabbing with the same conventional petroleum-based graphite
swabbing compound every 7 to 10 minutes. Further, these
molds without the precoating had to be removed from the
machine and cleaned after about 30 hours of operation in
order to continue further production.
E X A M P L E III
The composition as recited in Example I was em-
ployed to coat the molding surfaces of a rotary press ware
machine for forming 12 oz., drinking glasses. The glasses
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so formed were of excellent quality and had no "carbon marks"
upon the surfaces of the glasses.
While the s~ject invention is described in detail
in the several embodiments which this invention may assume
in practice, it will be appreciated to those skilled in the
art that changes and modifications may be made without de-
parting from the scope of the appended claims.
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