HOT MELT METAL WORKING LUBRICANTS

LUBRIFIANT POUR LE TRAVAIL DES METAUX EN FUSION

English Abstract

Title: HOT MELT METAL WORKING LUBRICANTS
Inventor: Richard William Jahnke
Abstract of the Disclosure:
Metal working operations, especially drawing, are
facilitated by applying to the metal a composition which
provides lubricity thereto and which melts within the range
of about 30-100°C. The composition comprises at least one
neutral ester, and preferably a mixture of esters, prepared
from polyalkylene glycols and saturated aliphatic alcohols
having at least about 10 carbon atoms, and C12-25 aliphatic
monocarboxylic acids and C4-20 aliphatic polycarboxylic
acids. The preferred ester mixtures are prepared from poly-
ethylene glycols, C14 -20 predominantly straight chain
alkanols, stearic acid and adipic, azelaic or sebacic acid.
Optional ingredients include phosphorus acid salts and anti-
oxidants. The composition may be applied in liquid form
and solidifies on cooling to normal ambient and storage
temperatures.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for lubricating metal during working
thereof which comprises applying to said metal a lubricating
composition which provides lubricity thereto, said composi-
tion melting within the range of about 30-100°C. and compris-
ing at least one substantially neutral ester defined as
follows:
I. The alcohol moieties are derived from
(A) a polyalkylene glycol containing about 20-50
polyoxyalkylene units, or a mixture thereof with
(B) at least one saturated aliphatic alcohol having
at least about 10 carbon atoms;
II. The acid moieties are derived from (C)
at least one C12-25 aliphatic monocarboxylic acid,
or a mixture thereof with (D) at least one C4-20
aliphatic polycarboxylic acid.
2. A method according to claim 1 wherein the
lubricating composition melts within the range of about
35-70°C.
3. A method according to claim 2 wherein the
ester is at least one ester of alcohol A and acid C.
4. A method according to claim 2 wherein the
ester is a mixture of at least one ester of alcohol A and
acid C and at least one ester of alcohol B and acid D,
the latter ester comprising about 5-95% by weight of said
mixture.
14

5. A method according to claim 4 wherein A is a
polyethylene glycol containing an average of 22-48 oxy-
ethylene units, B is a C14-20 predominantly straight-
chain alkanol or commercial mixture of such alkanols, C is
an alkanoic acid and D is at least one of adipic, azelaic
and sebacic acids.
6. A method according to claim 5 wherein C
is stearic acid.
7. A method according to claim 6 wherein the
working comprises drawing.
8. A method according to claim 2 wherein the ester
is a mixture prepared by reacting a mixture of alcohols A and
B with a mixture of acids C and D.
9. A method according to claim 8 wherein about
2-4 equivalents of A are present per equivalent of B in the
alcohol mixture, and about 2-4 equivalents of C are present
per equivalent of D in the acid mixture.
10. A method according to claim 9 wherein A is
a polyethylene glycol containing an average of 22-48 oxy-
ethylene units, B is a C14-20 predominantly straight-
chain alkanol or commercial mixture of such alkanols, C is
an alkanoic acid and D is at least one of adipic, azelaic
and sebacic acids.
11. A method according to claim 10 wherein C is
stearic acid.
12. A method according to claim 11 wherein the
working comprises drawing.

13. A method according to claim 2 wherein the
composition additionally contains a phosphorus acid salt
having the formula
<IMG>
wherein M is a Group I metal, a Group II metal, aluminum,
tin, cobalt, lead, molybdenum, manganese, nickel or ammonium;
each of R1 and R2 is a hydrocarbon-based radical; each of
X1, X2, X3 and X4 is oxygen or sulfur; and each of a and b
is 0 or 1.
14. A method according to claim 13 wherein M is
zinc; each of R1 and R2 is a lower alkyl radical; X1 and X2
are oxygen; X3 and X4 are sulfur; and a and b are each 1.
15. A method according to claim 14 wherein the
working comprises drawing.
16. A metal workpiece having on the surface
thereof a film of a lubricating composition which provides
lubricity thereto and which melts within the range of
about 30-100°C., said composition comprising at least one
substantially neutral ester defined as follows:
I. The alcohol moieties are derived from
(A) a polyalkylene glycol containing about 20-50
polyoxyalkylene units, or a mixture thereof with
(B) at least one saturated aliphatic alcohol having
at least about 10 carbon atoms;
II. The acid moieties are derived from (C)
at least one C12-25 aliphatic monocarboxylic acid,
or a mixture thereof with (D) at least one C4-20
aliphatic polycarboxylic acid.
16

17. A workpiece according to claim 16 wherein
the lubricating composition melts within the range of about
35-70°C.
18. A workpiece according to claim 17 wherein
the ester is at least one ester of alcohol A and acid C.
19. A workpiece according to claim 17 wherein
the ester is a mixture of at least one ester of alcohol A
and acid C and at least one ester of alcohol B and acid D,
the latter ester comprising about 5-95% by weight of said
mixture.
20. A workpiece according to claim 19 wherein
A is a polyethylene glycol containing an average of 22-48
oxyethylene units, B is a C14-20 predominantly straight-
chain alkanol or commercial mixture of such alkanols, C is
an alkanoic acid and D is at least one of adipic, azelaic
and sebacic acids.
21. A workpiece according to claim 20 wherein C
is stearic acid.
22. A workpiece according to claim 17 wherein
the ester is a mixture prepared by reacting a mixture of
alcohols A and B with a mixture of acids C and D.
23. A workpiece according to claim 22 wherein
about 2-4 equivalents of A are present per equivalent of B
in the alcohol mixture, and about 2-4 equivalents of C are
present per equivalent of D in the acid mixture.
17

24. A workpiece according to claim 23 wherein
A is a polyethylene glycol containing an average of 22-48
oxyethylene units, B is a C14-20 predominantly straight-
chain alkanol or commercial mixture of such alkanols, C is
an alkanoic acid and D is at least one of adipic, azelaic
and sebacic acids.
25. A workpiece according to claim 24 wherein C
is stearic acid.
26. A workpiece according to claim 17 wherein
the composition additionally contains a phosphorus acid
salt having the formula
<IMG>
wherein M is a Group I metal, a Group II metal, aluminum,
tin, cobalt, lead, molybdenum, manganese, nickel or ammonium;
each of R1 and R2 is a hydrocarbon-based radical; each of
X1, X2, X3 and X4 is oxygen or sulfur; and each of a and b
is 0 or 1.
27. A workpiece according to claim 26 wherein
M is zinc; each of R1 and R2 is a lower alkyl radical; X1
and X2 are oxygen; X3 and X4 are sulfur; and a and b are
each 1.
28. A composition which melts within the range
of about 30-100°C. and which provides lubricity to metal
surfaces, said composition comprising a mixture of sub-
stantially neutral esters defined as follows:
18

I. The alcohol moieties are derived from
(A) a polyalkylene glycol containing about 20-50
polyoxyalkylene units and (B) at least one
saturated aliphatic alcohol having at least about
10 carbon atoms;
II. The acid moieties are derived from (C)
at least one C12-25 aliphatic monocarboxylic acid
and (D) at least one C4-20 aliphatic polycarboxylic
acid.
29. A composition according to claim 28 which
melts within the range of about 35-70°C.
30. A composition according to claim 29 wherein
the ester is a mixture of at least one ester of alcohol A
and acid C and at least one ester of alcohol B and acid D,
the latter ester comprising about 5-95% by weight of said
mixture.
31. A composition according to claim 30 wherein
A is a polyethylene glycol containing an average of 22-48
oxyethylene units, B is a C14-20 predominantly straight-
chain alkanol or commercial mixture of such alkanols, C is
an alkanoic acid and D is at least one of adipic, azelaic
and sebacic acids.
32. A composition according to claim 31 wherein
C is stearic acid.
33. A composition according to claim 29 wherein
the ester is a mixture prepared by reacting a mixture of
alcohols A and B with a mixture of acids C and D.
19

34. A composition according to claim 33 wherein
about 2-4 equivalents of A are present per equivalent of B
in the alcohol mixture, and about 2-4 equivalents of C are
present per equivalent of D in the acid mixture.
35. A composition according to claim 34 wherein
A is a polyethylene glycol containing an average of 22-48
oxyethylene units, B is a C14-20 predominantly straight-
chain alkanol or commercial mixture of such alkanols, C is
an alkanoic acid and D is at least one of adipic, azelaic
and sebacic acids.
36. A composition according to claim 35 wherein
C is stearic acid.
37. A composition according to claim 28 which
additionally contains at least one phosphorus acid salt
having the formula
<IMG>
wherein M is a Group I metal, a Group II metal, aluminum,
tin, cobalt, lead, molybdenum, manganese, nickel or ammonium;
each of R1 and R2 is a hydrocarbon-based radical; each of
X1, X2, X3 and X4 is oxygen or sulfur; and each of a and b
is 0 or 1.
38. A composition according to claim 37 wherein
M is zinc; each of R1 and R2 is a lower alkyl radical; X1
and X2 are oxygen; X3 and X4 are sulfur; and a and b are
each 1.

39. A composition according to claim 28 which
additionally contains an antioxidant.
40. A composition according to claim 30 which
additionally contains an antioxidant.
41. A composition according to claim 32 which
additionally contains an antioxidant.
42. A composition according to claim 33 which
additionally contains an antioxidant.
43. A composition according to claim 35 which
additionally contains an antioxidant.
44. A composition according to claim 36 which
additionally contains an antioxidant.
45. A composition according to claim 38 which
additionally contains an antioxidant.
21

Description

107344Z
This invention relates to metal working operations.
More particularly, it relates to compositions useful as
lubricants and methods for lubricating metal during such ~ -
operations, and to metal workpieces so lubricated.
Metal working operations, for example, rolling,
forging, hot-pressing, blanking, bending, stamping, drawing,
cutting, punching, spinning and the like generally employ
a lubricant to facilitate the same. Lubricants greatly
improve these operations in that they can reduce the power
required for the operation, prevent sticking and decrease
wear of dies, cutting bits and the like. In addition, they
frequently provide rust inhibiting properties to the metal
being treated.
Since it is conventional to subject the metal to ~ -
various chemical treatments (such as the application of
conversion coating solutions) after working, a cleaning
operation is necessary between the working step and the
chemical treatment step. In addition to the above proper-
ties, therefore, it is preferred that the working lubricant
be easily removable from the metal surface by ordinary
cleaning compositions.
Heretofore, the lubricants applied for the above
purposes have ordinarily been liquids. The equipment used
for the application of such liquids is often expensive to ;
maintain and inconvenient to use. In addition, a dry-off
oven is usually required to remove the water or solvent
carrier from the liquid composition, which also greatly
adds to the capital costs and operating and maintenance
expenses of the method. Difficulties are also often
encountered in automatic feeding of metal blanks and other-
~ '-1-
~,
. ~ , . ., . ~ ::

1073442
wise handling the metal because the liquid compositions
which are normally applied to the metal make it wet and
slippery and consequently difficult to handle.
A principal object of the present invention, there-
fore, is to provide an improved metal working method.
A further object is to provide a method using
lubricants which impart to the metal being worked a unique
combination of properties including lubricity, corrosion
resistance, extreme pressure properties and protection
against wear of working parts, and which in addition are
relatively easy to remove from the surface of the metal by
cleaning after the working operation is completed.
A further object is to provide novel compositions
for use in the improved method.
Other objects will in part be obvious and will in
part appear hereinafter.
According to this invention, the above objects are
fulfilled by applying to the metal to be worked a composi-
tion which provides lubricity thereto, which melts within
the range of about 30-100C., and which comprises at least
one neutral ester defined as follows:
I. The alcohol moieties are derived from
(A) a polyalkylene glycol containing about 20-50
polyoxyalkylene units, or a mixture thereof with
(B) at least one saturated aliphatic alcohol having
at least about 10 carbon atoms;
II. The acid moieties are derived from
(C) at least one Cl 2-2 5 aliphatic monocarboxylic acid,
or a mixture thereof with (D) at least one C4-20
aliphatic polycarboxylic acid.
--2--
. .

~07344Z
Preferably, the composition melts to form a readily flowable
liquid which is capable of easy and efficient application to
the metal surface. One advantage of such a composition
(sometimes referred to hereinafter as the "hot melt composi-
tion") is that metals coated therewith are easier to handle
under normal storage conditions than metals coated with pre-
viously known lubricants.
The principal necessary characteristic of the hot
melt composition is its capability of providing lubricity to
the metal surface. For this purpose, lubricity may be de-
fined in many ways which are well known to those s~illed in
the art, and in terms of a number of test methods which, in
one way or another, simulate metal working operations. For
the purpose of this invention, a composition is deemed to
provide lubricity to a metal workpiece if its use results
in a deviation of 100 foot-pounds or less when tested by
the following method:
A cold-rolled steel strip, 2" x 13-1/2", is drawn
between two dies in an Instron Universal Tester, Model TT-C.
Prior to drawing, the edges of the strip are deburred and
the strip is vapor degreased and wiped with a clean cloth.
It is then coated uniformly with a drawing lubricant and
mounted in the testing machine. The dies are tightened by
means of a torque wrench set at 40 foot-pounds torque and
the strip is pulled through the die for two inches at the
rate of five inches per minute. The force or "load", in
foot-pounds, required to pull the strip through the die,
and the deviation from a uniform load, are recorded on a
chart.
The hot melt composition melts in the range of
30-100C., as previously indicated. Thus, it is solid at
--3--
-

107344Z
normal ambient temperature (e.g., about 20-30C.) and pressure.
The preferred melting range is 35-70C., with 38-55C. being
particularly desirable. When melted, the composition pre-
ferably forms a readily flowable liquid.
The principal ingredient of the hot melt composi-
tion is at least one substantially neutral ester (i.e., one
in which substantially all of the acid groups are esterified)
as defined hereinabove. The alcohols and acids from which
the ester is derived are more fully identified as follows:
Alcohol A is a polyalkylene glycol, usually a
polyethylene or polypropylene glycol and preferably the
former, containing about 20-50 polyalkylene units. Such
polyalkylene glycols are normally available as commercial
mixtures such as the "Carbowax" polyethylene glycols sold
by Union Carbide.
Alcohol B is at least one saturated aliphatic
alcohol having at least about 10 carbon atoms. Examples
are decanol, dodecanol, tetradecanol, stearyl alcohol,
eicosanol, and commercial mixtures of such alcohols, as
well as corresponding diols, triols, etc. Preferred are
Cl 4-2 o alcohols, especially alkanols (that is, saturated
monohydroxy alcohols) and more especially predominantly
straight-chain alkanols.
Acid C is at least one C~ 2-2 5 aliphatic monocar-
boxylic acid such as lauric, myristic, palmitic, stearic,eicosanoic, oleic or linoleic acid. Mixtures of such acids
are also suitable. The preferred acid is stearic acid.
Acid D is at least one C4-20 aliphatic polycar-
boxylic acid; examples are maleic, fumaric, succinic, adipic,
glutaric, pimelic, sebacic, azelaic, suberic and citric
3~ ~,toe ~"
--4--

107344Z
acids, as well as mixtures thereof. The preferred poly- -
carboxylic acids are dicarboxylic and especially adipic,
azelaic and sebacic acids.
A number of esters and ester mixtures are suitable
for use according to this invention. For example, esters
of alcohol A and acid C are useful; an example is the mono-
stearate of a polyethylene glycol containing an average of
about 22-48 oxyethylene units per molecule. The preferred
ester compositions, however, contain a plurality of alcohol
and acid moieties. Thus, they may comprise a mixture of at
least one ester of alcohol A and acid C and at least one
ester of alcohol B and acid D, typically containing about
5-95% by weight of the latter.
Especially preferred are mixtures of neutral esters
of alcohols A and B and acids C and D, and compositions
comprising such mixtures are within the scope of this inven-
tion. They are conveniently prepared by simply reacting the
alcohol mixture with the acid mixture, typically in the
presence of a strong acid as catalyst. Most often, the
alcohol mixture contains about 2-4 equivalents of A per
equivalent of B and the acid mixture contains about 2-4
equivalents of C per equivalent of D. (The equivalent
weight of an alcohol, for the purposes of this invention,
is its molecular weight divided by the number of hydroxy
groups per molecule and may be determined analytically,
especially for polyalkylene glycols. The equivalent weight
of a carboxylic acid is its molecular weight divided by
the number of carboxy groups per molecule.)
The preferred hot melt compositions contain, in
addition to the esters described hereinabove, at least one

~073442
agent to improve extreme pressure properties. The most
suitable extreme pressure agents are phosphorus acid salts
of the formula
X3
) a ~ !I x 4 M
R2(X2)b -
5 wherein M is a Group I metal, a Group II metal, aluminum,
tin, cobalt, lead, molybdenum, manganese, nickel or ammon-
ium; each of Rl and R2 is a hydrocarbon-based radical, each
of Xl, X2, X3 and X4 iS oxygen or sulfur; and each of a and
b is 0 or 1.
In the above formula, each of Rl and R2 is a hydro-
carbon-based radical. As used herein, the term "hydrocarbon-
based radical" denotes a radical having predominantly hydro-
carbon character within the context of this invention. Such
radicals include the following:
(1) Hydrocarbon radicals, which may be aliphatic
(e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl or
cycloalkenyl), aromatic, aliphatic- and alicyclic-substituted
aromatic, aromatic-substituted aliphatic and alicyclic, and
the like.
(2) Substituted hydrocarbon radicals, that is,
radicals containing non-hydrocarbon substituents which, in ~ --~
the context of this invention, do not alter the predominantly
hydrocarbon character of the radical. Suitable substituents
of this type will be apparent to those skilled in the art.
(3) Hetero radicals; that is, radicals which,
while predominantly hydrocarbon in character within the
context of this invention, contain atoms other than carbon
present in a chain or ring otherwise composed of carbon

107344Z
atoms. Suitable hetero atoms will be apparent to those
skilled in the art and include, for example, nitrogen,
oxygen and sulfur.
In general, no more than about three substituents
or hetero atoms, and preferably no more than one, will be
present for each 10 carbon atoms in the hydrocarbon-based -
radical.
The hydrocarbon-based radicals in the phosphorus
acid salt are ordinarily free from acetylenic and usually
also from ethylenic unsaturation and have no more than about
30 carbon atoms, desirably no more than about 12 carbon
atoms. They are usually hydrocarbon radicals such as methyl,
ethyl, propyl, butyl, amyl, hexyl, octyl, decyl, dodecyl,
vinyl, decenyl, cyclohexyl, phenyl and the like, all isomers
15 thereof being included. A particular preference is expressed `
for compounds in which Rl and R2 are lower alkyl radicals,
the word "lower" denoting a radical containing not more than
7 carbon atoms.
It will be apparent that the phosphorus acids from
20 which the salts are derived include dialkylphosphoric acids, -~
dialkylphosphinic acids, and thio derivatives of such acids.
Preferred are the salts in which X3 and X4 are each sulfur
and especially salts of phosphorodithioic acids; that is !
salts in which a and b are each 1 and Xl and x2 are each
oxygen. In the above-defined salts, M may be any of the
metals previously enumerated or ammonium; the latter term
includes substituted ammonium salts (i.e., amine salts).
M is preferably zinc or lead, especially zinc.
The hot melt composition most often contains up to
about 25% of the phosphorus acid salt as an optional ingredi-

1073442
ent. It is also within the scope of this invention to incor-
porate other known additives in minor amounts (typically
about 0.01-5.0% by weight) into the hot melt composition. Es-
pecially preferred other additives are antioxidants, typi-
cally hindered phenols; such materials are well known in theart. Other suitable additives useful in these proportions
include:
Surfactants, usually nonionic surfactants such as
oxyalkylated phenols and the like.
Auxiliary extreme pressure agents such as chlori-
nated waxes, sulfurized hydrocarbons, sulfurized esters, etc.
Corrosion and wear inhibiting agents, and auxiliary
rust inhibiting agents.
Friction modifying agents, of which the following
are illustrative: Alkyl or alkenyl phosphates of phosphites
in which the alkyl or alkenyl group contains about 10-40
carbon atoms, and metal salts thereof, especially zinc salts;
Cl0-20 fatty acid amides; C,0-20 alkyl amine/s, especially
tallow amines, and ethoxylated derivatives thereof; salts of
20 such amines with acids such as boric acid or phosphoric ~ -
acid which have been partially esterified as noted above;
Cl 0-2 0,alkyl-substituted imidazolines and similar nitrogen
heterocycles; sulfurized derivatives of sperm oil and other
fatty oils; basic barium or calcium salts of such oils or
of amine-formaldehyde condensates, especially those derived
from tallow amines such as described above; and gels derived
from basic alkaline earth metal sulfonates.
Melting point modifiers, typically relatively low
melting point esters such as dioctyl phthalate.
The invention also contemplates the use of hot melt

1~7344Z
lubricants containing waxes and waxy polymers, such as crystal-
line (including microcrystalline) and non-crystalline hydro-
carbon waxes, hydroxylated hydrocarbon waxes, petrolatum, and
low molecular weight olefin polymers, especially the poly-
ethylenes sold as "Bareco Polywaxes" by Petrolite Corporation.Such waxes or polymers are typically present in amounts of
about 0.25-1.0 part by weight per part of ester.
The hot melt composition may be prepared by in-
timately blending the ingredients thereof, preferably in the
liquid state, if more than one ingredient is involved. It
may sometimes be preferable to employ a substantially inert
liquid diluent to insure intimate blending. By "substantially
inert" is meant a diluent which does not undergo any appre-
ciable reaction with the ingredients of the composition under
the conditions of blending. Preferred as diluents are liquids
which are solvents for the ingredients being blended; suitable
solvents will be apparent to those skilled in the art and pre-
ferably comprise non-polar liquids such as benzene, toluene,
xylene, chlorobenzene and the like. After blending is com-
plete, the diluent is preferably removed, typically by evapora-
tion.
It is also within the scope of the invention to
incorporate a small particle size, pigment-type particulate
solid in the hot melt lubricant to increase lubricity at
temperatures above the melting point thereof. Suitable in
this respect are such pigments as rutile titanium dioxide,
anatase titanium dioxide, zinc oxide, leaded zinc oxide,
zinc sulfide, lead titanate, antimony oxide, zirconium
oxide, white lead, basic lead silicate, lithopone, titanated
lithopone, titanium-barium pigment, titanium-calcium pigment,
~ T~ _g_

107344Z
titanium-magnesium pigment, calcium carbonate, gilders
whiting talc, barytes, magnesium silicate, aluminum silicates,
diatomaceous earth, china clay, Asbestine, silica and mica.
Calcium carbonate is especially preferred. The amount of
such pigment is typically about 0.1-0.2 part by weight per
part of ester.
In the following table are listed typical hot melt
compositions suitable for use in the method of this invention.
--10--

107344;~
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1073442
Any metal to be worked may be treated according to
the mèthod of this invention; examples are ferrous metals,
aluminum, copper, magnesium, titanium, zinc and manganese
as well as alloys thereof and alloys containing other ele-
ments such as silicon.
The method of this invention includes any methodby which a metal workpiece may be coated with the hot melt
composition prior to or concurrently with the working
operation. For example, a cutting blade or drawing die may
be coated with the composition which is then transferred to
the workpiece by contact. More usually, however, the work-
piece is coated with the hot melt composition before the -~
working operation. Thus, this invention also contemplates
a metal workpiece having on its surface a film of the hot
melt composition, whether in solid or liquid form. The hot
melt composition will ordinarily form a continuous film
over the entire surface of the workpiece. However, it is
also within the scope of this invention to form a film on
less than the entire surface of the workpiece. ~ -
The physical state of the hot melt composition
during application to the metal surface is not critical.
Thus, it may be applied as a solid (as by rubbing) or as a
liquid (as by brushing, spraying, dipping, flooding, roller
coating, reverse roller coating or the like). For ease and
convenience of application, it is preferably applied in the
liquid state, and when this is done the metal may be subse-
quently cooled whereupon the hot melt composition solidifies,
or it may be passed directly to the metal working operation
while the composition is in the liquid state. Onelof the
advantages of this invention, however, is that the hot melt

107344Z
composition solidifies to form a solid, non-blocking, non-
slippery film on the metal workpiece, thus permitting con- i !
venient and safe material handling at reduced cost.
The surface temperature of the metal at the time - -
the hot melt composition is applied may vary, for example,
from normal ambient temperature to just below the decomposi-
tion temperature thereof. Factors which will influence or
determine the temperature of the metal at the time the
composition is applied include processes which the metal
is subjected to prior or subsequent to application of the
composition, the melting point of the composition, and the
temperature thereof at the time of application. Using the
hot melt compositions described hereinabove, metal surface ~-
temperatures of about 20-125C. at the time of application
have been found particularly useful. The temperature of the
hot melt composition should be higher than its melting
temperature (preferably at least 10C. higher and usually
about 20-40C. higher) at the time of application for ease
of flow and uniform dispersion of the composition onto the
metal and coverage thereby.
The melted hot melt composition may be applied to
the metal in a minimum of space utilizing existing equipment
such as coilers used in steel mills prior to coiling, and
because it quickly solidifies at ambient temperatures and
becomes dry, non-blocking and relatively non-slippery,
standard handling equipment such as lifting and feeding
rollers. Stackers and so on may also be used. The use of
the hot melt composition also eliminates the need for a
dry-off oven since there is no water or solvent to remove.
-13-
. .
. -;: