Note: Descriptions are shown in the official language in which they were submitted.
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Descriotion
COMPOSITION AND PROCESS FOR LUBIRICATED PLASTIC
WORKING OF METAI.S
FIELD AND BACKGROUND OF THE INVENTION
This invention relates to a highly effective cornposition for use in the
plastic
working of metals, for example, iron, steel, titanium, and aluminum. More
particular-
ly, this invention relates to a composition of the aforementioned type that
forms a
strongly-lubricating coating by a simple process in which, before a workpiece
is to be
subjected to plastic working, the composition is coated on the workpiece by
spray or
immersion and then dried. The invention also relates to processes for
lubricated
plastic working of metal, utilizing a lubricant composition according to the
invention.
A solid or fluid lubricant is generally used during the plastic working of
metals
in order to reduce the friction generated by metal to rnetal contact between
the tool
and workpiece and thereby prevent seizure and scarring. Lubricated processes
for
plastic working of metals can be broadly classified into two categories based
on the
method of use of the lubricant. Into one category falU processes in which
lubricants
are directly applied to the metal surface, while in the other category a
carrier film is
first formed on the metal surface by chemical reaction and then the
lubricating agent
is applied to the carrier film. The former category often utilizes lubricants
prepared
by the addition of an extreme-pressure additive to a base oil such as a
mineral oil,
vegetable oil, or synthetic oil. In this case the lubricant is applied to the
metal
surface and the plastic working operation is then carried out without
additional treat-
ment. The former category also can utilize lubricanits in which a solid
lubricating
agent such as a metal soap, graphite, or molybdenurri disulfide is dispersed
in water
along with a binder component. In this case the lubricant is applied to the
metal sur-
face and plastic working is carried out after a drying step.
Processes in which lubrfcants are directly applied to the metal category are
frequently used for tight plastic working because the lubricants can be
applied by
simple techniques such as painting and dipping and because they require little
or no
replenishment, concentration adjustments, or similar "management" of the
liquid
compositions used in them.
The other category of lubricated process for plastic working of metals
requires a chemical conversion coating. In the chemical conversion coating
approach, a carrier coating, most often a phosphate irype coating, is first
formed on
the metal surface by chemical reaction and the metal is then treated with a
lubricat-
ing agent such as a nonreactive soap or a reactive soap such as sodium
stearate or
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calcium stearate. The lubricating coatings formed by this process have a
double-lay-
er structure composed of the conversion carrier coating and the metal soap
lubricat-
ing agent and as a result exhibit a very high resistance to seizure. This
feature has
resulted in the use of lubricating coatings of this type i:n a very broad
range of plastic
working operations, e.g., wire drawing, pipe drawing, and forging.
Phosphate treatments, however, are known to have a number of problems.
Thus, phosphate treatments, because they are based on chemical reactions, have
required a complex bath management. They have allso required a large number of
treatment processes - including water and acid rinses - since the lubricating
agent
is applied after formation of a conversion coating. Phosphate treatments have
also
been associated with high plant and equipment costs and high operating costs
due
to the discharge of large amounts of effluent from the conversion coating and
the
water rinses used during the treatment and due to the necessity for heating in
order
to optimize the chemical reactions.
In order to address these problems, efforts have been made to raise the per-
formance of the directly-applied-to-the-metal category of lubricated processes
to a
level equivalent to that obtained by using lubricating coatings afforded by
phosphate
treatment in order to permit substitution of processes of the former type for
the
expensive phosphate treatments. These efforts have resulted in the appearance
of
methods that use oil-based lubricants and methods thiat use water-based
lubricants.
Within the realm of the oil-based lubricants, Japariese Published (Examined or
Kokoku) Patent Application Number Hei 4-1798 (1,798/1992) discloses
a"lubricant
for cold working in which a metal soap or solid lubricant is blended into a
lubricating
oil comprising a mixture of extreme-pressure additive (e.g., chlorinated
paraffin,
phosphate esters), isobutylene/n-butene copolymer, and animal oil or vegetable
oil".
However, even though this is a high=performance lubiricant, it nevertheless
exhibits
working characteristics that are somewhat inferior to those of lubricants
produced by
treatment with a reactive soap after a phosphate conversion coating treatment.
Another drawback of this high-performance lubricant is the unpleasant odor pro-
duced during plastic working operations that use it.
Water-based lubricants are either used wet without drying (wet method) or
are used in the form of a dried coating (dry method). The wet-method water-
based
iubricants are used by direct application to the tool oir workpiece, as in the
case of
the above-described oil-based lubricants, while the dry-method water-based
lubri-
cants are applied by immersion in the treatment bath, just as in the case of
the
above-described conversion coatings, followed by the production of a solid
lubricat-
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ing coating by evaporation of the water in a drying process. As an example of
the
wet-method water-based lubricants, Japanese Published (Examined or Kokoku)
Patent Application Number Sho 58-30358 (30,358/1983) discloses a"lubricant for
the cold- or hot-working of metal tubing comprising lthe blend of small
amounts of
s dispersant, surfactant, and solid lubricant in a bicarbonate (solids) main
component".
However, this lubricant has to date not achieved widespread use as a
substitute for
conversion treatments. An example of the dry-method water-based lubricants is
a
"lubricant composition comprising a blend of solid Ilubricant and conversion
film-
forming agent in a base of water-soluble polymer or its water-based emulsion"
that is
disclosed in Japanese Laid Open (Kokai or Unexamined) Patent Application
Number
Sho 52-20967 (20,967/1977). This example notwithstanding, dry-method water-
based lubricants equivalent to conversion treatments have not been obtained.
A major object of the present invention is to provide a lubricant composition
for the plastic working of metals that does not require a phosphate
undercoating, that
is is waterborne, that requires only a simple applii;,ation process consisting
of
immersion or spraying followed by drying, and that, at least in its most
preferred
embodiments, provides a lubricating performance equivalent to that afforded by
formation of a phosphate conversion coating on a metal workpiece and
application of
a lubricant composition to the conversion coating.
SUMMARY OF THE INVENTION
It has been found that a tough and highly tenacious coating is produced when
metal sheet is immersed in an aqueous solution or aqueous dispersion
containing
synthetic resin and water-soluble inorganic salt and is thereafter dried. The
in-
ventors also discovered that a particularly excellent Iubricating performance
can be
imparted to the obtained coating when the aqueous solution or dispersion also
con-
tains a lubricating agent, solid lubricant, and/or the like. This invention
was achieved
based on these discoveries. Embodiments of the invention include liquid
working
compositions that are suitable for directly treating metal surfaces, dried
solid
lubricating coatings formed by drying such working compositions and metal
workpieces bearing such solid lubricating coatings, concentrate compositions
from
which working compositions can be formed by dilution with water and/or by
mixing
with other concentrate compositions, lubricated metal plastic working
processes
lubricated by a dried composition according to the invention, and processes
for
preparing metal objects for plastic cold working by providing them with a
solid
lubricating coating by drying onto the metal objects a liquid coating of a
working
liquid composition according to the invention.
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More particularly, the invention provides A liquid composition that when dried
forms a solid lubricant for the plastic working of metals, said liquid
composition
comprising water and the following components:
(A) a component of dissolved, dispersed, or both dissolved and dispersed
synthetic
resin selected from the group consisting of polyvinyl alcohol,
polyvinvlpyrrolidone,
acrylic resins, vinyl acetate resins, epoxy resins, urethane resins, phenolic
resins,
and mixtures of any two or more of polyvinyl alcoholl, polyvinvlpyrrolidone,
acrylic
resins, vinyl acetate resins, epoxy resins, urethane resins, and phenolic
resins;
(B) a component of dissolved water-soluble iinorganic salt; and
(C) a lubricating agent component selected f'rom the group consisting of metal
soaps, waxes, polytetrafluoroethylene, oils, and mixtures of any two or more
of metal
soaps, waxes, polytetrafluoroethylene, and oils,
said components (A) and (B) being present in the composition in amounts
such that the ratio by weight of component (B) to component (A) is within a
range
from 0.25:1.0 to 9:1.0 and said component (C) constituting from 1 to 20
percent by
weight of the total liquid composition.
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DETAILED DESCRIPTION OF THE INVENTION AND ITS PREFERRED
EMBODIMENTS
A liquid lubricant composition according to the present invention for use in
forming a solid lubricant coating for the plastic working of metals comprises,
preferably
consists essentially of, or more preferably consists of, water and the
following
components:
(A) a component of dissolved, dispersed, or both dissolved and dispersed
synthetic
resin; and
(B) a component of water-soluble inorganic salt; and, optionally but
preferably,
(C) a component of lubricating agent that is not part of either of immediately
previously recited components (A) and (B); and, optionally but not necessarily
preferably,
(D) a component of extreme-pressure additive,
components (A) and (B) being present in amounts such that the ratio by weight
of
component (B) to component (A) is within a range from 0.25:1.00 to 9:1Ø
The synthetic resin (A) used in the lubricant composition according to the
present invention is not crucial as long as this resin has the ability to form
a coating that
has a film strength and adherence sufficient to withstand plastic working
operations.
Examples of suitable resins arepolyvinyl alcohols, polyvinylpyn-
olidones,acrylic resins,
vinyl acetate resins, epoxy resins, urethane resins, and phenolic resins.
These resins
can be either water-soluble or water-dispersible, and this particular property
is
preferably selected based on the intended use. For example, a water-soluble
synthetic
resin would be selected when the coating is to be washed away after plastic
working,
while a water-dispersible synthetic resin would be selected when resistance to
water is
required. The synthetic resin used by the present invention is dissolved or
dispersed in
the composition according to the present invention. Known surfactants can be
used as
necessary to effect dispersion. Although ordinarily, for convenience and
economy, only
a single resin type will be used in a composition according to the invention,
two or more
types of resins may be mixed and/or two distinct resins of the same type may
be mixed
in a composition according to the invention.
Polyvinyl alcohols areusually prepared by the hydrolysis of polyvinyl ace-
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tates, and the invention can use completely hydrolyzed poiyvinyl alcohols as
well as
polyvinyl alcohols having a degree of hydrolysis down to 50 %. For the
purposes of
the present invention, the polyvinyl alcohol category includes hydrolyzed
copolymers
of a mixture of ethylene and vinyl acetate in which at least 50 mole percent
of the
mixture is vinyl acetate and in which sufficient vinyl ac:etate residues have
been hy-
drolyzed so that at least 50 mole percent of the total of vinyl alcohol, vinyi
acetate,
and ethylene residues in the polymer are (formally) vinyl alcohol residues.
The mo-
lecular weight of the pofyvinyl alcohol is preferably from 300 to 2,000 as
measured
by gel permeation chromatography.
Polyvinylpyrrolidone resins suitable for use in the invention can be synthe-
sized by the polymerization of N-vinyl-2-pyrrolidone. For use in this
invention, the re-
sultsng polymer preferably has a molecular weight fromi 500 to 1,000 as
measured by
gel permeation chromatography.
The resins afforded by the polymerization of at least one type of acrylic mon-
omers are examples of acrylic resins suitable for use in the invention.
Suitable
acrylic monomers are exempiified by the alkyl (C = 1 1to 8) acrylates and
methacryl-
ates, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl
methacryl-
ate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-
ethylhexyl meth-
acrylate, and octyl acrylate; by lower alkoxy-lower alkyl acrylates and
methacrylates
such as methoxymethyl acrylate, methoxyethyl acrylate, ethoxymethyl acrylate,
ethoxyethyl acrylate, methoxymethyl methacrylate, methoxyethyl methacrylate,
ethoxymethyl methacrylate, ethoxyethyl methacrylate, and methoxybutyl
acrylate; by
lower hydroxyalkyl acrylates and methacrylates such as 2-hydroxyethyl acrylate
and
methacrylate and 3-hydroxypropyl acrylate and rnettiacrylate; by acrylamide
and
methacrylamide; by N-methylol-acrylamides and miathacrylamides, wherein the
methylol group may itself be unsubstituted or may be substituted and in
particular
may be substituted by lower alkoxy, e.g., N-methylolacrylamide, N-methylolmeth-
acrylamide, N-butoxymethylacrylamide, and N-butoxyrnethylmethacrylamide; by
low-
er phosphonyloxyalkyl acrylates and methacrylates such as phosphonyloxymethyl
acrylate, phosphonyloxyethyl acrylate, phosphonyloxypropyl acrylate,
phosphonyl-
oxymethyl methacrylate, phosphonyloxyethyl methacrylate, and phosphonylpropyl
methacrylate; and by acrylonitrile, acrylic acid, and me-thacrylic acid. The
invention
also encompasses acrylic resins that are copolymers containing at least 30
mole per-
cent of acrylic monomer units selected from the aforementioned acrylic
monomers
and at least one selection from other ethylenic monomers such as styrene,
methyl-
styrene, vinyl acetate, vinyl chloride, vinyltoluene, and ethylene. The
molecular
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weight of the acrylic resin is preferably from 1,000 to 1,000,000 and more
preferably
from 100,000 to 600,000, in each case as measured by gel permeation
chromatography.
Vinyl acetate resins suitable for use in the invention can be prepared by the
polymerization of vinyl acetate. For the purposes of the present description,
the term
"vinyl acetate resin" encompasses partially hydrolyzed homopolymers of vinyl
acetate in which less than 50 mole percent of the initially vinyl acetate
residues have
been hydrolyzed and vinyl acetate-ethylene copolymers containing at least 50
mole
percent of vinyl acetate residues. The vinyl acetate resin preferably has a
molecular
weight from 200 to 2,000 as measured by gel permeatiion chromatography.
Epoxy resins can be exemplified most promiinently by the bisphenol-type
epoxy resins - and particularly by the bisphenol-A epioxy resins that conform
to the
general formula:
O _ OH ~
~~O / ` ~ / O'1'~n O
is Such resins are afforded by the. reaction of epichlorohydrin and a
bisphenol and
particularly bisphenol-A (the formal systematic name of which is "2,2-bis(4-hy-
droxyphenyl)propane"). Other suitable epoxy resins can be exemplified by the
novo-
lac epoxy resins afforded by the glycidyl etherification of the phenolic
hydroxyl
moieties in a phenolic novolac resin, the glycidyl esters of aromatic
carboxylic acids,
and the so-called peracid epoxy resins produced by epoxidation with peracid of
the
double bond in an ethylenically unsaturated compourid. The subject epoxy
resins
can also be exemplified by the adducts of ethylene oxide or propylene oxide on
the
resin backbone of any of the above-noted other types of epoxy resins and by
the
glycidyl ethers of polyhydric alcohols. The bisphenol-A epoxy resins are the
most
preferred among the preceding examples. The epoxy iresin preferably has a
molecu-
lar weight of 350 to 5,000 as measured by gel permeation chromatography.
Urethane resins are synthetic resins that contain the urethane bond
(NHCOO). As a general matter; urethane resins suitable for the present
purposes
can be prepared by the polyaddition of a poiyisocyanate compound bearing at
least
two isocyanate groups and a polyol bearing at leasi: two active hydrogens. The
polyol used in this reaction can be exemplified by polyester polyols and
polyether
polyols. The polyester polyols can be exemplified by the hydroxyl-terminated
poly-
esters afforded by the reaction, for example, of a low molecular weight poiyol
and a
polybasic acid. The low molecular weight polyol can be, for example, ethylene
gly-
col, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-
propyiene glycol,
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neopentyl glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene
glycol, 3-
methylpentanediol, hexamethylene glycol, hydrogenated bisphenol-A,
trimethylolpro-
pane, and glycerol. The polybasic acid can be, for example, succinic acid,
glutaric
acid, adipic acid, sebacic acid, phthalic acid, isophthatic acid, terephthalic
acid, tri-
mellitic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid,
and
hexahydrophthalic acid.
Polyether polyols can be exemplified by the higher ethylene oxide and/or
propylene oxide adducts of low molecular weight polyols such as ethylene
glycol, di-
ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene
glycol, neo-
pentyl glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol,
3-methyl-
pentanediol, hexamethylene glycol, bisphenol-A, hydrogenated bisphenol-A,
trimeth-
ylolpropane, and glycerol; by polyether polyols such as polyethylene glycol,
poly-
propyiene glycol, and polymers of mixed ethylene and propylene glycols; and by
polycaprolactone polyols, polyolefin polyols, and poiybutadiene polyols.
The polyisocyanate can be, for example, an aliphatic, alicyclic, or aromatic
polyisocyanate. Specific examples thereof are tetrarnethylene diisocyanate,
hexa-
methylene diisocyanate, lysine diisocyanate ester, hyclrogenated xylylene
diisocyan-
ate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexyiinethane diisocyanate,
2,4'-di-
cyclohexylmethane diisocyanate, isophorone diisocyanate, 3,3'-dimethoxy-4,4'-
bi-
phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-
tetrahydronaphthalene
diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-
diphenylmeth-
ane diisocyanate, 2,4'-diphenylmethane diisocyanate, phenylene diisocyanate,
xylylene diisocyanate, and tetramethyixylylene diisocyanate.
A urethane resin used in the invention preferably has a molecular weight of
500 to 500,000 when measured by gel permeation chromatography.
Phenolic resins suitable for use in the invention can be obtained by reaction
of formaldehyde with at least one phenol selected froni, for example, phenol,
cresol,
and xytenol. The phenolic resin can be a novolac or re:sole resin. The use of
a nov-
olac resin requires the co-use of, for example, hexamethylenetetramine as
curing
so agent. Phenolic resin coatings are cured by the drying process discussed
below.
The molecular weight of the phenolic resin is not critical.
Commercially available products can of course be used as the resins refer-
enced above. The water-soluble synthetic resins can be acquired already
formulated
as the aqueous solution, while the water-insoluble synthetic resins can be
acquired
already formulated as a dispersion in which the resin is dispersed in water
using a
surfactant that, depending on the particular embodiment, can also be used for
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dispersion of the lubricating agent, vide infra.
The water-soluble inorganic salt component (B) as described above preferab-
ly is homogeneously dissolved in the solution and independently preferably
uniformly
precipitates with the synthetic resin during drying. Preferred salts
exhibiting the
desired behavior are one or more selections from the group consisting of
sulfate
salts, borate salts, molybdate salts, vanadate salts, and tungstate salts.
These may
be used individually or in combinations of two or more selections. Examples
thereof
are sodium sulfate, potassium sulfate, sodium borate, sodium tetraborate,
potassium
borate, potassium tetraborate, ammonium borate, arrimonium tetraborate, ammoni-
um molybdate, sodium molybdate, sodium tungstate, and sodium vanadate.
The {water-soluble inorganic salt component (IB)}/{synthetic resin component
(A) weight ratio), calculated on a solids basis, must be from 0.25:1 to 9:1.
The solid
coating will not be hard enough when this weight ratio falls below 0.25:1 and
the
metal workpiece will as a result suffer from seizure and/or scarring. When
this
weight ratio exceeds 9:1, the solid lubricating coating formed will suffer
from a re-
duced adherence and a reduced ability to follow the workpiece, during any
deforma-
tion thereof, which results in facile delamination of the film during the
working opera-
tion and hence in a reduction in lubrication. This (B)/(A) weight ratio is
preferably
from 0.3:1 to 8:1 and is more preferably from 0.5:1 to 71:1.
The characteristics of the produced film cani be adjusted by varying the
{water-soluble inorganic salt}/{water-solubte or -dispersible synthetic resin
weight
ratio), and an optimal weight ratio will exist as a function of the severity
of the
working or rubbing. Thus, the film becomes harder with an increasing
proportion of
water-soluble inorganic salt, and while this results in a better resistance to
loading it
also results in a reduced adherence by the film.
As an example, larger additions of the water-soluble inorganic salt are pre-
ferred in the case of severe plastic working operations such as closed
forging. More
specifically, in such cases the (B)/(A) weight ratio, calculated as the solids
weight
ratio, is preferably from 1.5:1 to 9:1, more preferably from 2:1 to 8:1, and
even more
preferably from 2:1 to 7:1. In the case, however, of the press working of thin
sheet,
lower proportions of the water-soluble inorganic salt are preferred, because
in such
operations it is desirable for the coating to have a beitter capaci#y to
follow or track
the workpiece. In this case the weight ratio under consideration is preferably
from
0.25:1 to 2:1 and more preferably from 0.3:1 to 2:1.
The synthetic resin and water-soluble inorganic salt are preferably present in
quantities such that the combined amount of the two substances (total solids)
is from
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1 to 20 percent by weight of a liquid composition according to the invention.
This
value is more preferably from 1 to 15 percent by weight and even more
preferably
from 3 to 10 percent by weight.
Among the optional components considered above, lubricating agent com-
ponent (C) is preferably generally present in the subject composition. The
lubricating
agent component should be stable in aqueous solution and should not impair the
film
strength. Examples of this component are metal soaps, waxes,
polytetrafluoroethyl-
ene, oils, and refractory solid lubricants. The metal soaps can be
specifically
exemplified by calcium stearate, aluminum stearate, barium stearate, lithium
stear-
ate, and zinc stearate; the waxes can be specificallly exemplified by
polyethylene
waxes, polypropylene waxes, carnauba wax, beeswax, and paraffin waxes; and the
polytetrafluoroethylene can be specifically exemplified by
polytetrafluoroethylenes
having a degree of polymerization of about 1 million to 10 million. The oils
can be
specificaliy exemplified by vegetable oils, mineral oils, and synthetic oils.
The veg-
etable oils can be exemplified by palm oil, rapeseed oil, and castor oil; the
mineral
oils can be exemplified by machine oil, turbine oil, and spindle oil; and the
synthetic
oils can be exemplified by ester oils and silicone oil:s. Examples of
refractory solid
lubricants are graphite, molybdenum disulfide, boron riitride, fluorinated
graphite, and
mica.
Lubricating agent component (C) will generally be present in a composition
according to the present invention in dispersed or emulsified form. The
lubricating
agent concentration in a liquid working composition according to the invention
is
preferably from 1 to 20 percent by weight, more preferably from 1 to 10
percent by
weight, and even more preferably from 2 to 7 percent by weight. A content
below 1
percent by weight can result in high film friction and Ihence in a strong
tendency for
seizure to occur, while a content in excess of 20 percent by weight may cause
the
film to suffer from a reduced adherence.
In the case of the invention composition containing components (A) and (B)
and lubricating agent and water, a first preferred embodiment thereof contains
0.3 to
10.0 percent by weight (as solids) of urethane resin as component (A), 1.0 to
10.0
percent by weight borate salt as component (B), lubricating agent, and water
with a
(B)/(A), calculated as the solids weight ratio, in the range from 0.25:1 to
9:1. With
regard to the urethane resin component, a content of at least 0.3 percent by
weight
is preferred in order to avoid a decline in film adhererice, while a content
no greater
than 10.0 percent by weight is preferred in order to avoid a decline in film
hardness
that would increase the likelihood of seizure. With regard to the borate salt
compon-
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ent, a content of at least 1.0 percent by weight is preferred in order to
prevent the
film from having an inadequate hardness that would result in scarring and
seizure of
the metal workpiece, while a content no greater ttian 10.0 percent by weight
is
preferred in order to avoid a loss in film adherence and extensibility that
would result
in facile delamination of the film during the working operation and hence in a
loss of
lubricating performance.
The preferred embodiment considered immediately above can use the same
types of lubricating agents and additions thereof as the invention in general.
When a composition according to the invention is intended to be used in
severe plastic working operations, the composition preferabty contains, as at
least
part of its content of component (C), a material selected from the group
consisting of
molybdenum disulfide, graphite, polytetrafluoroettiylene, boron nitrtde, mica,
fluorinated graphite, and mixtures of any two or rriore of molybdenum
disulfide,
graphite, polytetrafluoroethylene, boron nitride, mica, and fluorinated
graphite.' This
is material should be stable in the lubricating solid coating formed and
should function
to assist the high-load lubrication performance. The concentration of this
material in
a liquid composition according to the invention is preferably from 1 to 20
percent by
weight, more preferably from 1 to 10 percent by weight, and even more
preferably
from 1 to 5 percent by weight. Contents below 1 percent by weight risk an
inadequate resistance to seizure, while contents in excess of 20 percent by
weight
risk a reduced adherence.
The subject composition preferably also contaiins an extreme-pressure addit-
ive when it is intended to be used in very severe plastic working operations.
This ex-
treme-pressure additive should be stable in the lubricating solid coating
formed and
should exhibit an extreme-pressure activity at the tool=to-metal contact
surface pro-
duced by the working operation. Examples of such extreme-pressure additives
are
sulfur-containing, organomolybdenum, phosphorus-containing, and chlorine-con-
taining extreme-pressure additives, such as oiefin sulfides, sulfide esters,
sulfites,
thiocarbonates, chlorinated fatty acids, phosphate esters, phosphite esters,
mo-
lybdenum dithiocarbamate (hereinafter usually abbreviated as "MoDTC"), molybde-
num dithiophosphate (hereinafter usually abbreviated as "MoDTP"), and zinc
dithi-
3 If, on the other hand, a liquid lubricant composi#ion according to the
invention is
intended for use only in processes where there is relatively light plastic
working, ref-
ractory solid lubricants (i.e., those other than poiytetrafluoroethylene that
are noted in
this sentence) are preferably omitted from any component (C) that is present
in the
lubricant composition according to the invention.
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ophosphate (hereinafter usually abbreviated as ZnDTP).
The content of extreme-pressure additive component (D) when this compon-
ent is present is preferably from 0.5 to 5 percent by weight and more
preferably from
1 to 3 percent by weight. A content below 0.5 percent: by weight risks an
inadequate
extreme-pressure activity, while a content in excess of 5 percent by weight
risks a
reduced film adherence. Independently, the extreme-pressure additive is
selected
from the group consisting of sulfur-containing extreme-pressure additives, org-
anomolybdenum extreme-pressure additives, phosphorus-containing extreme-pres-
sure additives, and chlorine-containing extreme-pressure additives, and
mixtures of
any two or more of sulfur-containing extreme-pressuire additives,
organomolybden-
um extreme-pressure additives, phosphorus-containing extreme-pressure
additives,
and chlorine-containing extreme-pressure additives.
Nonionic, anionic, amphoteric, and cationic surfactants can be used when a
surfactant is required to disperse or emulsify the synthetic resin, solid
lubricant, other
1s lubricating agent, and/or extreme-pressure additive. The nonionic
surfactant is not
particularly critical and can be exemplified by polyoxyethylene alkyl ethers,
polyoxyal-
kylene (ethylene and/or propylene) alkylphenyl etheirs, the polyoxyethylene
alkyl
esters composed of polyethylene glycol (or ethylene oxide) and a higher fatty
acid
such as a C,2 to C18 fatty acid, and the polyoxyethylene sorbitan alkyl esters
com-
posed of sorbitan, polyethylene glycol, and a higher fatty acid such as a C12
to C18
fatty acid. The anionic surfactant is also not particularly critical and can
be exempli-
fied by fatty acid salts, the salts of sulfate esters, sulfonate salts, the
salts of phos-
phate esters, and the salts of dithiophosphate esters. The amphoteric
surfactant is
likewise not particularly critical and can be exemplified by amino acid-type
and be-
taine-type carboxylate salts, sulfate ester salts, sulfonate salts, and
phosphate ester
salts. The cationic surfactant is again not particularly critical and can be
exemplified
by aliphatic amine salts and quaternary ammonium salts. These surfactants can
be
used individually or in combinations of two or more.
The technique for preparing the lubricant composition according to the pres-
ent invention is not particularly critical as long as the resulting lubricant
composition
can satisfy the various conditions and specifications given hereinabove. The
presence of any of component (C) and/or (D) as described above in a liquid
compo-
sition according to the invention is preferably effectecl by mixing this
component in
the form of its waterborne dispersion or waterborne ernulsion with the other
compon-
ents. In one example of the preparation of the subject composition, an aqueous
solution or aqueous dispersion of the synthetic resin is added with vigorous
stirring to
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II!
CA 02334716 2000-12-11
WO 99/64544 PCT/US99/12364
an aqueous solution of the inorganic salt; a dispersion or emulsion of the
solid
lubricant, other lubricating agent, and/or extreme-pressure additive is
prepared using
surfactant and water as required; and the two intermediates are then combined
with
stirring.
Techniques for applying the lubricant composition according to the present
invention to the surface of the metal workpiece will riow be considered. When
the
plastic working operation consists of a single stage of plastic working, the
preferred
technique is to first blend the optional solid lubricant, other lubricating
agent, and/or
extreme-pressure additive (when one or more of these is used) into the
composition
comprising components (A) and (B) and water, then to apply the resulting
product,
which is in liquid form, as a coating to the metal workpiece, and then to dry
the liquid
coating to produce a solid coating according to the invention on the workpiece
before
it is worked. When the plastic working operation consists of multiple stages
of
plastic working, as are encountered in wire drawirig and forging, the
preferred
technique comprises application of the composition comprising components (A)
and
(B) and water to the metal workpiece, drying to procluce a film that functions
as a
carrier and partial lubricant itself, and carrying out thei plastic working
operation with
the additional application to the carrier film (for example, by dusting) of
the optional
solid lubricant, other lubdcating agent, and/or extreme-pressure additive at
each
2o stage of the working operation.
Thus, a lubricant composition according to the present invention preferably
additionally contains solid lubricant, other lubricating agent, and/or extreme-
pressure
additive as necessary when used in particular for the single-stage plastic
working of
metals, but also as desired in the case of multistage plastic working.
A lubricant composition according to the present invention can be used as the
lubricant that is employed during the cold plastic working (e.g., wire
drawing, pipe
drawing, forging) of metals such as iron, steel, copper, copper alloys,
aluminum,
aluminum alloys, titanium, and titanium alloys. The shape of the metal is not
par-
ticularly critical since the invention contemplates the working of not only
stock such
as bar and block, but also formed articles (gears and shaft toes) after hot
forging.
In order to obtain good results, prior to application of the lubricant composi-
tion according to the present invention, the surface of the metal workpiece is
prefer-
ably cleaned by a pretreatment comprising, in the ordler given, degreasing (an
alka-
line degreaser can generally be used), a water rinse, ain acid rinse (carried
out using,
for example, hydrochloric acid, in order to remove thei oxide scale on the
metal and
thereby improve film adherence), and a second water rinse. The acid rinse and
the
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WO 99/64544 PCT/US99/12364
ensuing water rinse can be omitted when metal oxide scaling is not present.
The lubricant composition according to the present invention can be applied
to the metal workpiece by the usual methods, such as dipping, spraying,, and
pouring. The application method needs only to provide a thorough coverage of
the
metal surface with the lubricant composition, and the application time is not
other-
wise a critical factor. A liquid lubricant composition according to the
invention must
be dried after its application before it is used to provicle lubrication.
While drying can
be effected by standing at ambient temperature, drying is optimally carried
out
generally at from 60 to 150 C for 10 to 60 minutes.
The post-coating, post-drying film coating weight afforded by the invention
composition is preferably at least 1 g/m2 from the standpoint of preventing
seizure,
but preferably does not exceed 30 g/m2 based on cost considerations. A more
pre-
ferred range is from 5 to 20 g/m2, while an even more preferred range is from
8 to 15
g/m2.
The invention and its advantageous effects will be explained more specifically
in the following through working examples.of the invention and comparative
examp-
les.
EXAMPLES 1 TO 3 AND COMPARATIVE E)CAMPLES 1 AND 2
The following pretreatment processes (1) and (2) were carried out on the test
specimen prior to application of the lubricant composiltion for Bowden
testing:
(1) Alkaline degreasing: FINECLEANER 4360 from Nihon Parkerizing Com-
pany, Limited, concentration = 20 g/L, temperature = 60 C, immersion for 10
minutes;
(2) Water rinse: spray with tap water at ambient temperature.
This pretreatment was followed by forced-convection dry'ing.
Lubricant compositions were prepared using the proportions reported in the
tables below. Each composition was prepared by dissolving the water-soluble
inor-
ganic salt in water followed by dissolution of the phenolic resin with
thorough stirring.
A cleaned and dried Bowden test specimen (SPC steel sheet, 150 mm x 75 mm x
1.0 mm) was dipped in the particular lubricant composition for 30 seconds,
dried at
100 C for 30 minutes, and then dusted over its entirety with calcium stearate
powder (from Nippon Yushi Kabushiki Kaisha) befo!re being submitted to Bowden
testing.
The coating weight in g/m2 was calculated from the weight difference before
33 and after application of the lubricant composition. The Bowden test used a
test load
of 5 kilograms (this unit being hereinafter usually abbreviated as "kg"), a
test temper-
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CA 02334716 2007-06-29
ature of room temperature (i.e., 18-23 C, and a 5 millimeters in diameter
steel test
sphere. The friction coefficient and number of strokes to seizure (number of
sliding
strokes until the friction coefficient reached 0.25) was measured in the
Bowden test. The
average friction coefficient reported in the tables is the average of the
friction
coefficients measured for the five strokes preceding and the five strokes
after the stroke
equal to one-half of the number of stokes to seizure.
EXAMPLES 4 TO 17 AND COMPARATIVE EXAMPLES 3 TO 6
Lubricant compositions were prepared using the proportions reported in the
tables below. Each lubricant composition was prepared by dissolving the water-
soluble
inorganic salt in water followed by the dissolution with thorough stirring of
the urethane
resin, polyvinyl alcohol, phenolic resin, or acrylic resin. The particular
lubricating agent,
i.e., polyethylene wax dispersion, calcium stearate dispersion,
polyterafluoroethylene, or
palm oil emulsion, as reported in the tables was then added with stirring to
give the
lubricant composition. The Bowden test specimens (SPC steel sheet, 150
millimeters x
75 millimeters x 1.0 millimeter), cleaned and dried as described for Examples
1 to 3,
were dipped in the particular lubricant composition for 30 seconds and dried
at 100 C
for 30 minutes and then submitted to Bowden testing. The Bowden test and
pretreatment of the Bowden test specimen were carried out as described for
Examples
1 to 3.
In addition to the Bowden test specimens, solid cylinders of commercial
spheroidized annealed S45C steel were used as backward punch test specimens in
Examples 4-17 and Comparison Examples 3-7. The backward punch test specimens
all
had diameters of 30 millimeters and each one had a height ranging from 16 to
40 mm in
2 millimeter increments and thus was one of thirteen different lengths. These
backward
punch test specimens were pretreated by the following processes (1) to (4)
prior to
coating with the lubricant composition:
(1) Alkaline degreasing: FINECLEANER 4360 from Nihon Parkerizing Company,
Limited, concentration = 20 g/L, temperature = 60 'C, immersion for 10
minutes;
(2) Water rinse: spray with tapwater at ambient temperature for 30 seconds;
(3) Acid rinse: hydrochloric acid, concentration = 17.5 percent by weight,
temperature = room temperature, dipping time = 10 minutes;
(4) Water rinse: spray with tapwater at ambient temperature for 30 seconds.
Pretreatment was followed by forced-convection drying. The thus cleaned and
dried
backward punch test specimens were dipped in each lubricant composition for 30
seconds, then completely dried by holding in a 100 C oven for 30 minutes, and
submitted to testing.
14
CA 02334716 2007-06-29
The backward punch test used a 200-ton crank press. In the backward punch
test procedure, the dies were set to bind the circumference of the cylindrical
test
specimens and the specimen was then subjected to a downward stroke from a
punch.
The punch had a diameter designed to give a 50 % cross section reduction of
the test
specimens and to produce a cup-like molding. The lower dead point of the press
was
adjusted to give a 10 millimeters residual margin at the bottom of the test
specimen. The
following characteristics also applied to the backward punch test: The dies
were SKD11;
the punch was HAP40, with an outside diameter of 21.21 millimeters; the punch
depths
were 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, and 60 millimeters,
respectively, for
the thirteen sizes of test specimens in order of increasing heights of the
test specimens,
and the working rate of the punch was 30 strokes/minute. Backward punch
testing was
run on the test specimens in order of increasing height until damage occurred
to the
worked surface. The good punch depth was designated as the largest inside
height of
the test specimen cup at which the inner surface remained undamaged.
COMPARATIVE EXAMPLE 7
Bowden test specimens and backward punch test specimens as described for
Examples 4 to 17 were subjected to conversion treatment and then reactive soap
lubrication treatment using the conditions reported in the tables. The
resulting test
specimens were subjected to Bowden testing and backward punch testing also as
described for Examples 4 to 17.
EXAMPLES 18 TO 34
Lubricant compositions were prepared using the proportions and materials
reported in the tables. After following the procedure described for Examples 4
to 17, a
refractory solid lubricant or an extreme-pressure additive as specified in the
tables was
added after the particular solid lubricant or extreme-pressure additive had
been
preliminarily dispersed into water, using an amount of polyoxyalkylene
alkylphenyl ether
nonionic surfactant that corresponded to 2 percent of the weight of the solid
lubricant or
extreme-pressure additive being dispersed.
Application, Bowden testing, and backward punch testing were then carried out
as described for Examples 4 to 17.
The results of the various tests described above are reported in the tables
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CA 02334716 2000-12-11
WO 99/64544 PCT/US99/12364
below. These results confirm that Examples 1 to 34, which employed lubricant
com-
positions according to the present invention for ttie plastic working of
metals,
provided a superior lubricating performance using a simple procedure. In
contrast,
Comparative Examples 1 to 6, which either did not contain both components re-
quired according to the invention or contained these components in ratios to
each
other outside the range specified for the invention, were all unable to
provide both an
excellent lubricating performance and simple proceiss features. The phosphate
coating produced in Comparative Example 7 did exhibit a lubricating
performance
equal to that of the present invention, but required a large number of steps
and could
not be implemented using simple facilities.
The components referenced in Tables 1 to 3 and their abbreviations are def-
ined below, except for those components that have already been noted together
with
their abbreviations above.
Phenolic resin (molecular weight = 500 to 6,000): phenol novolac made water
45 soluble by amination. This component is abbreviated in the tables as PR.
Urethane resin (molecular weight at least 50,000): produced by the
polyaddition of
polyethylene glycol (molecutar weight = 1,000) and hexamethylene diisocyan-
ate. This component is abbreviated in the tables as UR.
Acrylic resin: copolymer of acrylic acid, methyl mettiacrylate, and n-butyl
acrylate;
2o molecular weight at least 150,000; surfactarit used = polyoxyethylene al-
kylphenyl ether. This component is abbreviated in the tables as AR.
PVA: polyvinyl alcohol with a molecular weight of 1,000.
PE wax: This was a polyethylene wax emulsion prepared by the emulsion polymeri-
zation of ethylene. Molecular weight = 16,000 to 20,000. This component is
25 abbreviated in the tables as PEW.
Polytetrafluoroethylene wax: from Sumitomo 3M. This component is abbreviated
in
the tables as PTFE.
Calcium stearate dispersion: from Chukyo Yushi. This component is abbreviated
in
the tables as CaStD.
30 Palm oil emulsion: a dispersion of palm oil using poiyoxyalkylene
alkylphenyl ether.
This component is abbreviated in the tables as PaOE.
Sulfurized vegetable oil: product of Nippon Yushi. The abbreviation for this
compon-
ent in the tables is SVO.
Phosphite ester: product of Sakai Kagaku. The abbreviation for this component
in
35 the tables is P3E.
NaW: sodium tungstate
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WO 99/64544 PCT/US99/12364
NaMo: sodium molybdate
KTB: potassium tetraborate
NaTB: sodium tetraborate
KV: potassium vanadate
KS: potassium sulfate
CaStP: calcium stearate powder
GP: graphite powder
FGP: fluorinated graphite powder
MDS: molybdenum disulfide powder
The percent by weight reported for each component in the tables is the
percent by weight of the identified component itself. Thus, in the case of
aqueous
dispersions as an example, this value will not include the water and
surfactant used
for the dispersion.
The preceding description makes it clear that the lubricant composition ac-
cording to the present invention for application to the plastic working of
metals has
the ability to form a highly lubricating film through a simple process. This
composi-
tion also produces only small amounts of wastes and provides a good working
envir-
onment.
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WO 99/64544 PCT/US99/12364
TABLE 1
Examples 1 to 3 and Comparative Exarriples 1 and 2
Iden Components
tify- Water-Soluble Synthetic Other Dispersed Dusted
ing Inor nic Salt Resin Com onent Material
N~ Weight Weight Weight
bers ~terial % Material % Material %
WORKING EXAMPLES
1 NaW 2 PR 4 CaStP
2 NaMo 4 PR 6 CaStP
3 KTB 4 PR 6 CaStP
COMPAR.ATIVE EXAMPLES
1 NaW 9.5 PR 1 - CaStP
2 NaW 0.5 PR 4 CaStP
.... Table I is continued below....
Ratio by BowdenTest Results
Weight of
Identifying Water-Soluble Coating
Inorganic Salt Weight, Average Number of
Numbers to gimz Friction Strokes to
Synthetic Coefficient Seizure
Resin
WORKING F.XAMPLES
1 0.50 8.2 0.15 625
2 0.67 7.1 0.13 482
3 0.67 7.0 0.13 523
COIVCrnxATNE EXAMPLES
1 9.5 8.1 0.18 212
2 0.13 8.7 0.15 128
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WO 99/64544 PCT/US99/12364
TABLE 2.
Examples 4 to 17 and Comparative Examples 3 to 7
Ident- Components
Water-Soluble Synthetic
Other Dispersed Component
~g Inor anic Salt Resin
Num-
bers Materia Weight Material Weight Material Weight %
1 % %
4 NaW 3 PR 1 PEW 5
NaW 3 PVA 1 PEW 3
6 NaW 6 UR 2 PEW 5
7 NaMo 3 PR 1 PEW 3
8 KTB 3 PR 1 CaStD 3
9 KV 3 PR 1 CaStD 5
KS 3 AR 1 C'aStD 3
11 NaTB 3 UR 1 PEW 5
12 NaTB 3 UR 3 PEW 5
13 NaTB 3 UR 8 PEW 5
14 NaTB 2 UR 1 CaStD 3
KTB 3 UR 5 CaStD 3
16 KTB 3 UR I PTFE 5
17 KTB 8 UR 1 PaOE 3
3 NaW 9.5 PR 1 PEW 3
4 NaW 0.5 PVA 4 PEW 3
5 NaW 3 - PEW 5
6 - UR 3 PEW 5
Zinc phosphate coating treatment Reactive soap lubrication treatment
PALBOND 181X from Nihon PAI.UBE 235 from Nihon
7 Parkerizing Co., Ltd. (concentration = 90 Parkerizing Co., Ltd.
(concentration
g/L) = 70 g/L)
Treatment conditions: dipping, 10 Treatnzent conditions: dipping, 5
minutes, 80 C minutes, 80 C
... Table 2 is continued on the next page...
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iC
CA 02334716 2000-12-11
WO 99/64544 PCT/US99/12364
Table 2 Continued from the previous page
Ratio by Test Results
Weight of
Water-Soluble Bowden Test Backward
Identifying Inorganic Salt 1e Coating Pnnch:
Numbers to g~z Average Number of Good
Synthetic Friction Strokes to Punch
Resin Coefficieni: Seizure Degth,
Millimeters
WORKING EXAMPLES
4 3 8.7 0.08 635 44
3 9.1 0.09 425 44
6 3 11.8 0.07 823 44
7 3 9.2 0.09 740 44
8 3 10.2 0.08 735 44
9 3 10.1 0.07 631 44
3 9.7 0.08 688 44
11 3 9.0 0.09 688 44
12 1 12.2 0.08 823 44
13 0.38 11.1 0.07 888 44
14 2 8.8 0.09 510 44
0.60 8.5 0.09 635 44
16 3 12.3 0.07 912 44
17 8 9.5 0.08 823 44
CoMPARATNE EXAMPLES
3 9.50 9.1 0.18 158 40
4 0.13 10.4 0.12 210 36
5 - 8.2 0.21 112 28
6 - 9.7 0.11 69 20
Conversion Film Weight:5.8
Metal Soap Weight: 2.3
7 Hot-Water Soluble Soap Weight: 0.10 409 44
2.5
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WO 99/64544 PCT/US99/12364
TABLE 3.
Examples 18 to 34
Components
Example Water-Soluble Synthetic Resin Next Dispersate Final Dispersate
Number Ino 'c Salt Added Added
Material % by Material % by Material % by Material % by
Weight Weight Weight Weight
18 NaW 3 PR 1 PEW' 3 MDS 2
19 NaW 6 PR 1 PEW 3 GP 2
20 NaW 3 PVA 1 PEW 3 BN 2
21 NaW 7 PVA 1 PEW 3 FGP 2
22 NaW 3 PVA 1 PEW 3 SVO 1
23 NaW 3 PVA 1 PEW 3 MoDTC 1
24 NaW 3 PVA 1 PEW 3 MoDTP 1
25 NaMo 2 AR 1 PEW 3 ZnDTP 1
26 KTB 6 AR 1 PEW 3 MDS 2
27 KV 6 AR 1 PEW 3 MDS 2
28 KS 6 AR I PEW 3 MDS 2
29 NaTB 3 UR 3 PEW 3 GP 2
30 NaTB 3 UR 3 PEW 3 MDS 2
31 NaTB 3 UR 3 PEW 3 BN 2
32 NaTB 3 UR 3 PEW 3 P3E 2
33 NaTB 3 UR 3 PEW 3 MoDTC 1
34 NaTB 3 UR 3 PEW 3 ZnDTP 1
....Table 3 is continued on the next page....
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WO 99/64544 PCT/US99/12364
Table 3 continued from the previous, page
Ratio by Test Results
Weight of
Water-Soluble Coating Bowden Test Backward
Identlfying Inorganic Salt Weight, ~~:
Numbers ~ g(m2 Average Number of G~ p~cb
Friction Strokes to
Synthetic Resin Coefficient Seizure Depth,
Millimeters
18 3.00 11.2 0.15 822 48
19 6.00 10.6 0.12 862 48
20 3.00 11.2 0.17 685 44
21 7.00 11.1 0.16 624 44
22 3.00 9.8 0.11 612 44
23 3.00 9.2 0.14 741 44
24 3.00 9.1 0.15 618 44
25 2.00 8.2 0.11 589 44
26 6.00 11.5 0.16 854 48
27 6.00 11.7 0.17 727 48
28 6.00 10.7 0.16 818 48
29 1 10.3 0.12 623 48
30 1 9.2 0.11 624 48
31 1 10.3 0.12 521 48
32 1 9.3 0.08 812 44
33 1 10.8 0.10 441 44
34 1 9.3 0.08 452 44
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