Hot melt lubricant and method of application

A dry Non-Oil metalworking lubricant that can be applied by a hot melt application. This dry lubricant is completely water soluble, provides rust protection, cleans from surfaces with plain room temperature water, and is more environmentally safe than other lubricants. A polyethylene glycol of sufficiently high molecular weight to be solid at room temperature is combined with amines, rust inhibitors, and metalworking additives to produce a thin film that provides protection for the part and the tooling in a metalworking operation. This lubricant provides further benefits to the overall process such as; easy to clean, weld through capability, excellent paint system compatibility, and environmentally superior to other lubricants.

BACKGROUND OF THE INVENTION 
The present invention allows metalstampers the flexibility of using a hot 
melt lubricant for coating coils of strip steel or coating blanks that are 
then worked at the press. Metalstampers perform operations such as; 
stamping, drawing, bending, forming, blanking, punching, cutting, rolling, 
forging, and other types of metalworking. 
Lubricants are designed to reduce friction between the metal being worked 
and the tooling. This reduces the amount of energy necessary to make the 
part. It reduces damage to the part and the tooling during the 
metalworking operation. The lubricant should also provide protection from 
staining and corrosion of the part and the tooling. The lubricant should 
prevent sticking of the part and the tool and also prevent sticking of one 
part to another. 
In general there are two types of compositions which are used to effect a 
temporary rust-prevention and/or forming lubrication of steel plates, one 
of which is the liquid film type, contains components capable of improving 
the rust-proof and lubrication added into a base oil, for example, mineral 
oil, animal oil, or vegetable oil, such as, metal working oil, and 
anti-rusting oil, etc., and the other of which is of the solid film type 
and contains a fatty acid, or fatty acid soap as the main constituent. 
In comparing both types, the liquid coating type has the disadvantage that 
when the steel plates are fabricated by press forming some of the coating 
drops onto the floor and a dangerous slipping hazard exists. Moreover, the 
environment is polluted by the bad odor and scattering of the liquid which 
soils the clothes of the operators. Also, formability can not be kept 
constant because the coating can not be held for long periods in the 
quality or quantity necessary for forming. 
On the other hand, the solid coating does not present such problems. But 
known solid coating compositions must be dissolved in hot water, or an 
organic solvent before use, and the steel plates coated with the solution 
must be heated to dryness to remove the water or the solvent. 
On the one hand, the solid coating type has a better effect on stamping 
than the liquid coating type as mentioned above. On the other hand, the 
coating process prior to forming is more complicated, and requires 
facilities for coating and for drying by heating. Further, heating lowers 
the quality of the steel sheet itself due to the strain aging effect, so 
that it is not common to apply the solid coating type in place of the 
liquid coating type. 
However, when steel plate makers manufacture steel plates coated with 
rust-proof lubricant compositions of the solid film-type, users can 
directly place the coated steel plate into the forming operation without 
encountering the above-mentioned problems so that improvements in the 
operating conditions and productivity to counterbalance the additional 
costs will be easily achieved. 
Rust-proof lubricants of the solid film-type are classified as of the 
solvent-type, aqueous solution-type, and reaction type. 
The principal constituents of the solvent-type, such as, fatty acid, 
extreme pressure additives, rust-preventives, etc., must be dissolved in 
an organic solvent before applying it on steel plates. In the case of the 
aqueous solution type, the principal constituents which are metal soaps of 
fatty acid and certain water-soluble organic compounds and inorganic 
compounds must be dissolved in hot water, and the coating applied on metal 
plates is dried by heating to form a solid film. In the reaction type, 
there is a lubricant comprising a phosphate-fatty acid soap. However, 
these conventional rust-proof lubricant compositions of the solid film 
type have many disadvantages, e.g.: 
(1) The solvent-type uses an organic solvent so that when a large amount of 
the composition is used, for example, in the process for coating coils of 
steel sheets continuously, there arise the dangers from fire and 
explosion, sanitary problems, and special facilities are thus made 
necessary. Even if a highly noncombustible solvent is used, operators will 
not be free from the sanitary problems, such as bad odor, poisoning by 
solvent, etc., and special facilities are thus made necessary. Further, 
the waste gases produced when drying present pollution problems. 
Additional problems include difficulty in degreasing in a short period of 
time in the surface-treating step after the forming operation. 
(2) The aqueous solution type does not have the above-mentioned danger from 
fire, or poisoning by solvent, because of the use of water, but high 
temperatures and long periods of time are necessary for drying, so that it 
is not only difficult to apply at a high speed on coils of steel plates, 
but also it is unsuitable to use for aging steel plates of which the 
mechanical properties are lowered by heating. Furthermore, since there is 
a close relationship between the melting point of compositions of the 
solid film-type and pressing formability, the conventional water-soluble 
coatings are, in most cases, composed of compounds having high melting 
points, such as fatty acid soaps and do not melt at the time of stamping. 
In the drawing process, coating film is rubbed off by the die surface and 
especially by the die throat, and then fragments of the coating film pile 
on the die surface which hinders the steel plates from sliding into the 
dies. Further, the film does not have enough fluidity to cover again the 
naked surface rubbed off by drawing in larger sizes, therefore, causing 
pressing damages or reducing the pressing formability. 
(3) The reaction-type complicates both the coating treatment and the 
subsequent removal treatment. 
As has been mentioned above, while the conventional rust-proof lubricants 
have many defects, the present invention overcomes all of these defects 
and provides compositions having very important properties. 
It has also been taught that there can be problems associated with the wet 
application of a dry film. Drying equipment can be costly and 
significantly slow down the coating process. Equipment used in such an 
operation can also require a large amount of floor space which is also an 
added cost. 
Air quality in metalstamping plants is always a concern. Very few 
operations continue to use volatile organic solvents in their operation 
due to the potential health and flammability hazard associated with them. 
Most typical lubricants are low volatility liquids that minimize the 
possibility of air contamination. 
Some dry films add to air quality problems. Odors or dust from some dry 
films are undesirable to press operators. Dust from stearate soap type dry 
films has been known to cause respiratory problems for workers. Increased 
precautions are required for workers such as dust masks. Plant operation 
costs increase because of the need for ventilating and filtering equipment 
necessary to improve the air quality. 
Many parts are welded to one another in the metalstamping industry. 
Fabricators are trying to make their process more efficient by reducing 
steps. One way to save time and energy costs is to eliminate washing of 
parts before welding. Any lubricant that is burned should not pose a 
toxicity hazard. Lubricants that burn cleanly without large volumes of 
smoke and odor are preferred. The lubricant must leave no residue to 
ensure the integrity of the weld. 
Lubricants that were able to make the most difficult parts were usually the 
hardest to clean. Chlorinated paraffins and pigmented pastes are good 
examples of materials that are hard to clean. Some newer materials, 
although easier to clean, still rely on alkaline cleaners for removal from 
metal surfaces. Some products even claim high temperatures are not 
necessary to remove their product but they still require elevated 
temperatures (120F.-140F.) to remove the lubricant. These products are 
generally formulated with surfactants to help improve their cleanability. 
Waste streams that contains such compounds are typically more toxic to 
aquatic life. 
Chemical compatibility of the lubricant with the process after the part is 
formed is an important consideration. Parts are often cleaned and painted. 
E-coat systems are very sensitive to chemical contamination, which can 
cause paint defects. The further along the process a defect occurs, the 
more costly it is to the process. Stopping paint defects becomes as 
important as forming the part. Lubricants that do not clean easily or that 
become trapped in areas of severe bending, can cause problems in a paint 
system. Weeping of a lubricant from a trapped area can occur after the 
washing of the part, providing an area that may be more difficult to paint 
and therefore cause a defect. Therefore compatibility with cleaning and 
paint systems is a must. 
SUMMARY OF THE INVENTION 
A dry non-oil metalworking lubricant that can be applied by a hot melt 
application. This dry lubricant is completely water soluble, provides rust 
protection, cleans from surfaces with plain room temperature water, and is 
more environmentally safe than other lubricants. A polyethylene glycol of 
sufficiently high molecular weight to be solid at room temperature is 
combined with amines, rust inhibitors, and metalworking additives to 
produce a thin film that provides protection for the part and the tooling 
in a metalworking operation. This lubricant provides further benefits to 
the overall process such as: easy to clean, weld through capability, 
excellent paint system compatibility, and environmentally superior to 
other lubricants. 
A principal object of this invention is to provide improved metal working 
lubricant compositions, a method for application of the lubricant, provide 
easy to remove lubricants, and to provide an environmentally safe material 
in all cases. 
Another object and advantage of this invention is that the hot melt 
lubricant is solid at room temperature and therefore does not drip onto 
the floor like liquid coating lubricants. 
Another object and advantage of this invention is that it can be dissolved 
in room temperature water and does not require hot water or organic 
solvents like solid film type lubricants comprised of fatty acids or fatty 
acid soaps. 
Another object and advantage of this invention is that it does not require 
heating in order to dry the metal substrate to remove water or solvent. 
Still another object and advantage of this invention is that is non-toxic 
and non-combustible and does not present pollution problems such as is the 
case with solvent-type solid film lubricants of the prior art. 
Another object and advantage of this invention is that the lubricant can be 
welded through without leaving a residue to interfere with the integrity 
of the weld and without producing toxic smoke. 
Still another object and advantage of this invention is that it can be 
cleaned from the metal substrate with room temperature water. 
Another object and advantage of this invention is that it is compatible 
with paint systems so that the paint system will not be impaired by 
chemical contamination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The dry, non-oil, water-soluble metalworking lubricant of the present 
invention comprises a mixture of polyethylene glycol and an amine. 
Preferably, the polyethylene glycol is of sufficient molecular weight to be 
solid at room temperature. 
The polyethylene glycol preferably is of low enough molecular weight that 
it is soluble in water at room temperature. 
It has been found that a molecular weight in the range of 8,000 to 20,000 
is preferable, although this range should not be taken as limiting. 
Typical commercial products which may be used as the polyethylene glycol 
component include polyethylene glycol compound 20M and Carbowax 
polyethylene glycol 8000 from Union Carbide Chemicals and Plastics 
Company, Inc., Danbury, Conn. 
The amine component is preferably an aliphatic amine. Preferably, the 
aliphatic amine is selected from the group consisting of triethanolamine, 
diethanolamine, monoethanolamine, triisopropanolamine, diisopropanolamine, 
and monoisopropanolamine. Commercial products which are usable as the 
amine component include AMP-95 (2-amino-2-methyl-1-propanol) from ANGUS 
Chemical Company; isopropanolamine mixture product code 42150 from Dow 
Chemical Company; and triethanolamine, 99% low freezing grade (PM-4024) 
from Union Carbide Chemicals and Plastics Company, Inc. 
The dry, non-oil, water-soluble metalworking lubricant of the present 
invention may also include water. Water helps to reduce the viscosity of 
the material being mixed and reduces the amount of heat required to get 
all the components into solution. The addition of water during the coating 
process can reduce the viscosity of the melt and allow for lower coating 
weights of the dry film than could be achieved without it. This is 
possible due to the complete water solubility of all the components in the 
formula. 
Preferably, the dry, non-oil, water-soluble metalworking lubricant of the 
present invention comprises a mixture of polyethylene glycol, amine, and 
water in the proportions of 35% to 75%, 1% to 25%, and 0% to 30%, by 
weight, respectively. 
The dry, non-oil, water-soluble metalworking lubricant of the present 
invention may also include a rust inhibitor. Rust inhibitors can be varied 
to provide as little or as much rust protection as necessary. The rust 
inhibitor must be water soluble and compatible with polyethylene glycol. A 
commercial product that may be used is Idasol D-845 amine complex from 
Ideas, Inc. 
The dry, non-oil, water-soluble metalworking lubricant of the present 
invention may also include polyalkylene glycol as a metalworking 
lubricant. Typical commercial products that may be used are UCON 
Metalworking Lubricant EPML-483 and UCON Metalworking Lubricant ML-566, 
both from Union Carbide Chemicals and Plastics Company, Inc. 
The dry, non-oil, water-soluble metalworking lubricant of the present 
invention may also include a phosphate ester extreme-pressure additive and 
lubricant. A typical commercial product is Chemax P-Phos-7 organic 
phosphate ester from Chemax, Inc. 
The dry, non-oil, water-soluble metalworking lubricant of the present 
invention may also include a surfactant. Typical commercial products 
include IGE CO-630 from Rhone-Poulenc, Cranbury, N.J.; and ANTAROX 
BL-225, also from Rhone-Poulenc. 
Another component of the dry, non-oil, water-soluble metalworking lubricant 
of the present invention may be borax (sodium tetraborate decahydrate), 
commercially available from U.S. Borax. 
A biocide material may also be included in The dry, non-oil, water-soluble 
metalworking lubricant of the present invention to keep microbes and molds 
from affecting the product. Typical commercial products are BUSAN 1060 
from Buckman Laboratories, Lake Placid, N.Y.; and BIOBAN P-1487 from Angus 
Chemical Company, Buffalo Grove, Ill. 
Without being limiting, a preferred formula for The dry, non-oil, 
water-soluble metalworking lubricant of the present invention is: 
______________________________________ 
Component Preferred % Range % 
______________________________________ 
Water 20.0 0-30 
Amine 16.0 0-25 
Polyethylene 47.9 35-75 
glycol 
Rust Inhibitor 
6.4 0-15 
Polyalkylene 3.2 0-15 
glycol 
Phosphate 6.4 0-15 
ester 
Surfactant 0.1 0-5 
Borax 0-5 
Biocide 0-5 
______________________________________ 
EXAMPLES 
______________________________________ 
A. CLEANING TESTS (wt. in grams) 
Sample A B C D E 
______________________________________ 
Water 20.0 20.0 0.0 20.0 20.0 
Amine 16.0 16.0 16.0 16.0 16.0 
PEG 20M 47.9 0.0 0.0 0.0 0.0 
Carbowax 0.0 47.9 47.9 47.9 47.9 
Rust Inhibitor 
6.6 6.4 6.4 6.4 0.0 
Polyalkylene 
3.2 3.2 3.2 3.2 3.2 
glycol 
Phosphate 6.4 6.4 6.4 6.4 6.4 
ester 
Surfactant 0.1 0.1 0.1 0.0 0.1 
______________________________________ 
These samples were compared to a competitive straight oil product and a 
competitive soluble oil product for the ability to be cleaned from a metal 
substrate at room temperature. A copper strike test was used to determine 
cleanability according to the following procedure: 
Coat four cleaned 1".times.2" cold rolled steel strips with product by 
dipping the test strip into the product to be tested. Stand strips upright 
and allow excess to run down. Put one of the strips in the oven for an 
hour @180.degree. F.). Let the other air dry. 
Weigh out 40 grams of a 4% solution of copper sulfate into a 50 ml beaker. 
To make up the solution for one sample: 
______________________________________ 
copper sulfate 1.6 grams 
DI water 38.4 grams 
______________________________________ 
Prepare a beaker of 150 grams of 77.degree. F. tap water. Put the beaker on 
the stirrer and set at 1.5 on new magnetic stirrer. Hang one of the panels 
into the water for 30 seconds. Remove the test strip from the water. 
Put the copper sulfate solution on the stirrer and set at 6. Hang the 
cleaned panel in the copper sulfate solution for 30 seconds. Remove the 
panel and determine the amount of copper plated to the steel. If the test 
strip has a uniform shiny copper color, then the panel is clean. 
Repeat for the other test strip using a fresh solution of copper sulfate. 
______________________________________ 
Cleanability Data - Copper Strike Test 
______________________________________ 
Sample A Pass 
Sample B Pass 
Sample C Pass 
Sample D Pass 
Sample E Pass 
Str Oil Fail 
Sol Oil Fail 
______________________________________ 
B. RUST INHIBITION TESTS 
The above samples were tested for inhibition of rusting of cast iron. The 
results are as follows, as compared to a competitive straight oil product 
and a competitive soluble oil product. 
Samples were tested for their rust inhibiting effect according to the 
following procedures: 
Clean the cast iron plate for the rust test. ALWAYS WEAR SAFETY GLASSES 
WHEN POLISHING THE PLATE WITH THE DRILL. Use the brown Scotchbrite buffer 
to polish the plate and remove any rust or stains. For hard to remove 
impurities, attach the green Combi-S buffer. Afterwards, use the sanding 
screens to smooth out the surface. 
PETROLEUM ETHER IS EXTREMELY FLAMMABLE. ONLY USE THIS MATERIAL IN A 
WELL-VENTILATED AREA LIKE THE HOOD. 
When the surface is smooth and clean, take the plate to the hood and wipe 
the surface with a paper towel saturated with petroleum ether to remove 
any dirt and oil. Repeat once. Do not throw the paper towels into the 
garbage immediately. Set them in the hood to allow the Petroleum ether to 
evaporate from the towels. 
Prepare the dilutions for the test. Generally, more concentrated dilutions 
are placed on the left. Also, it is rarely necessary to make 100 gram 
samples of each test solution. There are two ways to prepare the 
dilutions. The first method minimizes weighing errors and is faster than 
method 2. Method 2 can be done without the use of a calculator. 
Method 1: 
Put a clean beaker on the balance and press the zero bar. Add a small 
amount of the product to be tested. Higher dilutions need less sample than 
the lower dilutions. 
Example: To make about 10 grams of a 10% dilution, use about 1 gram of 
product. To make about 10 grams of a 2% dilution, use about 0.2 grams. 
Read the weight of the amount added and enter it into the calculator. 
Multiply this number by 100 and then divide that number by the desired 
dilution percentage. Add water to the beaker until the number on the 
calculator and the number displayed on the balance match. 
Example: weight of sample.times.100/desired percentage=total weight. 
EQU 0.534 grams.times.100/4=13.350 
In this example, 0.534 grams of product were put in the beaker and then DI 
water was added until the balance displayed 13.350 
Method 2: 
An 8% dilution can be prepared by weighing 8 grams of product into a 
plastic beaker and then filling the beaker up with DI water for a total of 
100 grams (that means 92 grams of water are being used). For convenience, 
dilutions may be made out of a 25 gram total. For an 8% dilution, 2 grams 
of product are combined with DI water for a total of 25 grams. 
8 g. product divide top by 4=2 g. product=0.08 or 
100 g. total divide bottom by 4 25 g. total 8% dilution For a 1% dilution: 
1 g. product divide top by 4=0.25 g. product=0.01 or 
100 g. total divide bottom by 4 25 g. total 1% dilution 
Testing prepared solutions: 
Arrange the filter paper squares on the plate. Place the plate in the large 
Kimax beaker and replace the cover. Make sure there is water in the bottom 
of the large beaker. Start with the most dilute sample from each product. 
The samples need to be well mixed. Draw fluid into the dropper and then 
squeeze it out several times to ensure the solution is well mixed. Work 
from right to left, proceeding from the most dilute to the most 
concentrated. Remove as much of the previous fluid as possible from the 
dropper before proceeding to the next solution. Lift the lid only as far 
as necessary to add the fluid to the square. Add enough fluid so that the 
paper is saturated, but not enough so that the fluid runs into the next 
square (about 3-4 drops). 
Make a diagram of what the samples are and their dilutions on a note card. 
Identify products by rows and dilutions by columns. Write down the time 
and the date the test was started. Tests usually run about three hours. If 
large amounts of rust occur early, stop the test sooner. Record the time 
that the test was concluded. 
______________________________________ 
Cast Iron Rust Test 
______________________________________ 
Sample A 
4% 
Sample B 
4% 
Sample C 
4% 
Sample D 
4% 
Sample E 
7% 
Str Oil 
8% 
Sol Oil 
6% 
______________________________________ 
Samples formulated as below were also tested for rust inhibition in 
long-term storage of metal substrates. 
______________________________________ 
Rust Inhibition Tests 
Sample A B 
______________________________________ 
Water 20.0 20.0 
Amine 16.0 16.0 
PEG 20M 47.9 0.0 
Carbowax 8000 0.0 47.9 
Rust Inhibitor 6.4 6.4 
Polyalkylene 3.2 3.2 
glycol 
Phosphate 6.4 6.4 
ester 
Surfactant 0.1 0.1 
______________________________________ 
The above formulas were coated onto to Q-panels for long-term storage 
evaluation. 
______________________________________ 
Sample A B 
______________________________________ 
3 months stable film, no rust 
stable film, no rust 
6 months stable film, no rust 
stable film, no rust 
9 months stable film, no rust 
stable film, no rust 
______________________________________ 
C. LUBRICITY TESTS 
Blanks were coated with each lubricant. Parts were stamped in two 
operations. The temperature of the part was measured using an infrared 
thermometer. The hottest spot on the part was found and this area was used 
for the comparison of the parts and the lubricants. It is assumed that the 
lubricant that provides lower part temperatures is reducing friction and 
providing better part quality and longer tool life. Results on the samples 
as formulated under "CLEANING TESTS" were as follows: 
______________________________________ 
First Operation Second Operation 
Avg. Temp. 
No. Parts Avg. Temp. 
No. Parts 
______________________________________ 
Comparison of Sample A with Competitive Sample on 23" Blanks 
Sample A 168.0 9 223.5 8 
Competitive 
174.3 7 252.4 8 
Comparison of Sample A with Competitive Sample on 17" Blanks 
Sample A 135.3 7 212.8 5 
Competitive 
165.0 5 227.5 4 
Comparison of Sample B with Competitive Sample on 23" Blanks 
Sample B 152.0 7 191.5 8 
Competitive 
168.0 5 205.2 5 
______________________________________ 
A hot melt method for coating a metal substrate with a metalworking 
lubricant of the above formulations is also disclosed, comprising the 
steps of: 
melting a solid lubricant comprised of polyethylene glycol and an amine, 
applying the melted lubricant to the metal substrate, and 
allowing the melted lubricant to solidify on the metal substrate. 
Optionally, the method may further comprise a cleaning step before the 
melting step to remove chemical contaminants. Substrates for coating need 
to be free of contaminants including mill oil that may be applied to the 
substrate by the supplier. This process allows for great flexibility in 
processing the incoming material. It can be put in line with a blanking 
line and a washer. Blanks can be coated and stored for later use. The 
coater could also be the first step in the press line. 
The method may further comprise applying the melted lubricant to the metal 
substrate by roll coating. 
The solid lubricant is readily meltable at an elevated temperature, above 
room temperature, for ease of application to the substrate with the 
lubricant in a molten state. Typically, a melting temperature for the 
solid lubricant is in the range of 115-180 degrees F. 
The coating is preferably applied by a roll coater that has the following 
adjustments: (a) heating mechanism that can readily change the temperature 
of the molten lubricant. Cold conditions may require higher temperatures. 
Higher temperatures decrease the viscosity of the lubricant which can be 
related to the coating weight of lubricant applied to the substrate; (b) 
adjustable nip roll to facilitate the adjustment of coating weight as 
necessary; (c) adjustable gap between the coating rollers to facilitate 
different substrate thicknesses. The gap between the rollers can be used 
to alter the coating weight as well; (d) ability to change application 
rolls. Rolls can be coated with different materials of different hardness. 
Harder rolls are able to apply less lubricant. Rolls can be configured to 
coat only part of the substrate or be grauviered for other special 
applications; (e) ability to change the speed of the rollers. Higher 
speeds generally mean higher coating weights, therefore controlling the 
speed is necessary to coat the product as desired; (f) a heating vessel 
for the lubricant that can hold and mix the lubricant for uniformity and 
applicators that can supply the molten lubricant to the application rolls. 
As shown in FIG. 1, the roll coating mechanism preferably comprises two 
rubber coating rolls 8 (which may be heated), one for coating each side of 
workpiece S. Doctor rolls 9, in contact with coating rolls 8, can be 
horizontally adjusted so as to regulate the thickness of the hot melt 
lubricant M on the coating rolls, which themselves may be vertically 
adjusted so as to regulate the amount of said lubricant transferred to 
workpiece S. 
This process does not require the use of post-coating techniques to make 
the coating uniform like ovens to reflow the lubricant or quenching 
stations to cool it. This provides further energy savings and floor space 
savings. 
Other application methods and equipment can be used such as: spray systems, 
drip systems, dip systems, and hand application of lubricant. The 
lubricant can even be applied in the solid form by rubbing. 
The method preferably produces a solid lubricant coating which is 
essentially translucent. This provides the benefit of seeing whether the 
substrate is coated with the lubricant but does not mask defects on the 
surface of the substrate. 
The present invention may be embodied in other specific forms without 
departing from the spirit or essential attributes thereof, and it is 
therefore desired that the present embodiment be considered in all 
respects as illustrative and not restrictive, reference being made to the 
appended claims rather than to the foregoing description to indicate the 
scope of the invention.