Note: Descriptions are shown in the official language in which they were submitted.
WO 94/16119 21~ 3 3 31 PCT/US94/00212
Description
;~- ,..
~COMPOSITION AND PROCESS FOR TREATING METAL"
Technical Field
The present invention relates to a composition, often denoted hereinafter
as a Ubath" for brevity, for treating metal surfaces and to a film formation pro-
cess, wherein said bath and process are applicable for the formation of lubricat-
5 ing films prior to the cold working of metals and particularly of carbon steels,low alloy steels, stainless steels, steels plated with zinc or zinc alloy, titanium
metal and alloys thereof, aluminiferous metals, and the like.
Background Art
The formation of a lubricating film on metals prior to their cold working
0 typically consists of the following two separate steps in the case of light cold
working operations: the initial formation of a conversion film on the surface ofthe workpiece as a base layer treatment; the subsequent formation on this film
of a lubricating film through the application of a lubricant. Thus, the completelubrication treatment process comprises both a conversion step and a lubrica-
5 tion step.
Very high pressures (surface pressures) generally occur between theworkpiece and tool during the cold working of metal. As a result, when the
crystal lattice spacing (lattice constants) of the tool and workpiece are similar,
the workpiece and tool ultimately weld together and bond to each other. These
20 regions of the tool and workpiece are then torn away, leading to the occurrence
of the phenomenon known as seizure. Direct contact between the workpiece
and tool must therefore be avoided in order to prevent this problem. This ob-
jective is accomplished mainly through the use of a base layer film formed by
conversion treatment as described above. At present, lubrication treatments
25 consisting of the combination of such a base layer film and an appropriate lubri-
cant are in widespread use in the metal cold working sector. The quality of the
lubrication capacity exercised by the films formed by such lubrication treatment
WO 94/16119 PCT/US94/00212
2 ~ 3 31
processes is related to the performance of the top layer lubrication film, but it
is primarily controlled by the performance of the base layer conversion coated
film.
On the other hand, recent remarkable advances in metal working tech-
5 nology have made possible operations even under mechanically extremely se-
vere working conditions. However, the lubrication performance has not kept
pace with these advances, and at present the performance limits of the base
layer film define the limits of the lubrication performance. It is for this reason
that major improvements in the performance of the base layer film (the so
10 called lubrication film carrier) are desired.
Conversion treatment baths based on inorganic acid or low molecular
weight organic acid (oxalic acid, etc.) are a technology already known as a use-ful point of departure for improving the lubrication carrier performance of the
base layer films. Japanese Patent Application Laid Open [Kokai or Unexam-
ined] Number Sho 62-174386 [174,386/1987] is an example of the addition of
organic polymer to such conversion treatment baths in order to bring about an
improvement in lubrication performance. Here, an improvement in lubrication
performance is obtained by improving the film's adherencé through the addition
of water soluble organic polymer (excluding proteins) to an oxalate based film
20 forming agent. The water soluble organic polymers listed for addition in the ref-
erenced patent are nonionic and have highly hydrophilic structures. In tests runby the present inventors, moderate improvements in the lubrication perform-
ance were observed, but major performance improvements were not achieved.
Examining this matter from the perspective of the essential nature of lubrication,
25 films that contain these highly hydrophilic structures do bring about a reduction
in contact between tool and workpiece basis metal, but they lack the high level
lubricating property of simply reducing the friction coefficient that operates be-
tween the film and tool surface.
WO 94/16119 21~ 3 3 31 PCT/US94/00212
Disclosure of the Invention
Problems to Be Solved by the Invention
The present invention responds to the demands generated by the per-
formance limits that characterize the prior art in the metal cold working sector.
- s The present invention does this by providing both a bath and a process for
treating metal surfaces for the formation thereon of composite films for the cold
working of metal, wherein said bath and process provide major improvements
in tool life, working degree or ratio, working speed, and the like.
Summary of the Invention
As the result of extensive research in response to the demands de-
scribed above, the inventors discovered that a high level lubrication perform-
ance is achieved by the formation on the metal surface of a composite film us-
ing a conversion treatment bath that contains a special type of organic polymer
or salt thereof.
Specifically, the present invention relates to a bath for treating metal sur-
faces for the formation thereon of composite films for the cold working of metal,
wherein said bath characteristically comprises a conversion treatment bath that
contains organic cationic polymer having at least 1 cationic nitrogen atom per
polymer molecule and having a molecular weight of 1,000 to 1,000,000 or that
contains a salt of an aforesaid organic cationic polymer.
The present invention also relates to a process for the formation of com-
posite films for the cold working of metal, wherein said process is characterized
by the formation of a composite film by treating the surface of a metal with a
conversion treatment bath that contains organic cationic polymer having at least1 cationic nitrogen atom per polymer molecule and having a molecular weight
of 1,000 to 1,000,000 or that contains a salt of an aforesaid organic cationic
polymer.
The composite film that is the subject of the present invention consists
of a film in which resin and inorganic crystals have formed a composite. In thiscomposite film, the resin (= organic cationic polymer or salt thereof) has pene-
WO 94/16119 ~ 1 ~ 3 3 31 PCT/US94/00212
trated into and resides in the grain boundaries between the inorganic crystals
that are formed by the conversion treatment bath.
The metal surface treatment bath used by the present invention com-
prises a base conversion treatment bath in which organic cationic polymer (or
5 salt thereof) is dissolved or stably dispersed. Sald base conversion treatmentbath is selected from the known phosphate treatment baths, oxalate treatment
baths, and fluoride containing treatment baths, and should be selected as ap-
propriate to the type of metal undergoing treatment. For example, when the
treatment substrate is carbon steel, low alloy steel, steel plated with zinc or zinc
10 alloy, or aluminum, the bath can be selected as desired from the usual phos-
phate treatment baths. The phosphate treatment baths are exemplified by zinc
phosphate baths, zinc/calcium phosphate baths, and manganese phosphate
baths. Oxalate treatment baths are used for stainless steels, and fluoride con-
taining treatment baths are used for titanium metals and aluminum metals.
5 These fluoride containing treatment baths are made up from fluoride and an in- organic acid such as sulfuric acid or phosphoric acid, etc.
The organic polymer present in the metal surface treatment bath of the
present invention should contain at least 1 cationic nitrogen atom per polymer
molecule and should have a molecular weight of 1,000 to 1,000,000.
20 Preferably, with increasing preference in the order given, the molecular weight
of the polymer does not exceed, 500,000, 250,000, 100,000, 50,000, 30,000,
or 22,000. Although the chemical nature of the polymer, except for the
requirement to contain cationic nitrogen, is not restricted, organic polymers
defined as follows are particularly preferred: organic polymers that contain at
25 least 1 type of resin skeleton selected from epoxy resins, urethane resins, poly-
butadiene resins, acrylic resins, and maleic anhydride resins.
Suitable salts of the organic cationic polymer encompass inorganic acid
salts (e.g., phosphoric acid salts, nitric acid salts, sulfuric acid salts, etc.) and
organic acid salts (e.g., propionic acid salts, gluconic acid salts, etc.) of the
30 above described organic cationic polymers. These organic cationic polymers
WO 94/16119 215 3 3 ~ 1 PCT/US94/00212
and salts thereof can be used individually or in combinations of two o! more.
The improvement in lubrication performance is poor when the organic polymer
has a molecular weight less than 1,000. When its molecular weight exceeds
1,000,000, it becomes highly problematic to obtain its solution or stable
- 5dispersion in the base conversion treatment bath. Still lower molecular weights
as already noted above provide even more effective results.
Other types of resins, activators, etc., can also be added as necessary.
The metal surface treatment process in accordance with the present in-
vention can be implemented by a spray or immersion conversion treatment or
oby electrolytic treatment, but the mechanical aspects of the treatment processusing the treatment agent of the present invention are not specifically restricted.
The above described conversion film is used in combination with an ov-
erlayer or top layer of lubricant; however, the type of this lubricant is not specif-
ically restricted. Operable in this regard are certainly the soap lubricants, oils,
5and mineral oil lubricants that are currently in the most widespread use for met-
al cold working. Synthetic organic lubricants, etc., are also useable in this
regard.
For example, micropowders of calcium soaps are typically used as lubri-
cants in the wire drawing of steel wire. The organic polymer deposited in the
20grain boundaries of the conversion film crystals functions to promote a robustand continuing adherence by this lubricant to the surface of the steel wire. Dueto this excellent carrier function, the lubricant under consideration is delivered
in larger quantities to the die during wire drawing. This improvement in delivery
efficiency results in a highly favorable lubrication performance. This in turn
25makes possible such effects as an improvement in die life, an increase in the
wire drawing velocity, and an increase in the cross section reduction.
In pipe drawing and forging, an immersion treatment is generally carried
out at ambient or elevated temperature using a water soluble sodium soap lub-
ricant, oil (straight or emulsified), or mineral oil lubricant. The deposited organic
30polymer does not dissolve out, exfoliate, or delaminate even in these treatments
W O 94/16119 215 ~ 3 3 I PC~rrUS94/00212
and remains strongly adherent. This results in the development of excellent
lubrication effects and avoids any restrictions on the lubricant's use conditions.
Finally, in the press working sector, an excellent lubrication performance
is again developed due to the same effects discussed above for wire drawing,
pipe drawing, and forging. The lubricants used in this sector normally consist
of oils that contain extreme pressure additives, as represented by the usual
press oils. This type of oil resists removal in degreasing processes, and its re-
moval after working is therefore quite problematic. When a composite lower
layer conversion film has been formed using the metal surface treatment bath
o in accordance with the present invention, the use of a high viscosity oil (e.g.,
press oil, etc.) as the upper layer lubricant becomes unnecessary, and a thor-
oughly satisfactory lubrication performance can be obtained even using a low
viscosity anticorrosion oil. This produces the advantage of easy removal of the
oil after the working operation. Moreover, since a conversion film has already
been laid down on the workpiece, coating or painting can be carried out immed-
iately after degreasing. In addition, the organic polymer containing composite
film also gives excellent post painting properties. The present invention is
strongly differentiated from the prior art films that contain water soluble organic
compounds because the latter make only a small contribution to the lubrication
performance and give extremely poor post painting properties.
The organic polymer is generally added to the conversion treatment bath
at 0.1 to 50 grams per liter (hereinafter often abbreviated "9/LH) as solids. With
increasing preference in the order given, the amount of cationic polymer dis-
solved and/or dispersed in the conversion treatment bath will be from 0.5 to 40,1.0 to 27, 1.7 to 20, 2.5 to 11, 3.0 to 8.7, 3.5 to 7.5, or 4.0 to 6.0, g/L as solids
It has been found to be very difficult to obtain similar film deposition and
formation of a composite film structure when an anionic or nonionic organic poly-
mer is used in place of the organic cationic polymer as specified above.
When a metal surface is subjected to a conversion treatment, the basis
metal is ordinarily eluted and the pH of the conversion treatment bath increases
WO 94/16119 PCT/US94/00212
21~3~31
at its interface with the metal. The mechanism underlying conversion film for-
mation consists of the deposition of insoluble inorganic salts due to the increase
in pH and the formation--and deposition--of insoluble salts formed between
the eluted metal ion and components of the conversion treatment bath.
- 5 The organic cationic polymer present in the conversion treatment bath
in accordance with the present invention is dissolved or dispersed in the water
in cationic form. It appears that the pH increase, in the close vicinity of the
metal surface, associated with conversion coating as noted above, promotes
deposition of the organic cationic polymer by reducing its solubility or dispersi-
bility. In consequence thereof, when a metal is treated with the surface treat-
ment agent in accordance with the present invention, the organic polymer ap-
parently precipitates simultaneously with the inorganic salts and a composite
film is thereby formed.
The organic polymer particir~tes in the formation of the composite film
by precipitating in the form of solid resin in the grain boundaries of the conver-
sion film crystals. This appears to induce an improvement in the adherence of
the conversion film to the basis metal. In addition, at the extreme pressure lub-
rication conditions encountered during the cold working of metals, a film is
formed that apparently prevents metal/metal contact between the workpiece
and tool and that thus functions like an extreme pressure film. This results in
a major improvement in lubrication performance and particularly in resistance
to seizure.
The present invention is characterized by the use of a conversion treat-
ment bath that contains organic cationic polymer or salt thereof. Thus, for ex-
ample, the effects are minor when the surface of the metal workpiece is first
treated with the base conversion treatment bath and then treated with a solu-
tion that contains organic cationic polymer or salt thereof. In this case, a resin
film is merely formed on top of the conversion film and formation of a compos-
ite film does not occur, with the result that exfoliation of at least the polymer
film during cold working becomes quite easy. The working examples provided
WO 94/16119 PCT/US94/0021 ~
2 1 ~ 3 ~ 3 1
hereinafter will CGnfi~ that the composite film in accordance with the present
invention achieves a high level of lubrication performance.
Examples
Working examples of the present invention are provided below along with
comparison examples in order to demonstrate the effects of the invention in
specific detail. However, the invention is not limited to the examples, which are
provided simply as individual examples of surface treatment in support of cold
working in general.
1. Test materials
o The form, material, and dimensions of the tested metals are reported
below.
Carbon steel: hard steel wire, SWRH62A, 2.05 mm in diameter
Galvanized steel: steel sheet hot-dip galvannealed on both sides (add-on for
each side: 60 g/m2), 0.8 mm thick
Stainless steel: pipe, SUS304, 46 mm in diameter x 4 mm thick x 5000
mm long
Aluminum: forging grade, 51S (Alcoa designation)
2. Surface treatment agents tested
Table 1 reports the type of pretreatment and pretreatment
20 conditions for the various test materials. Table 2 reports the type and
conditions for the base conversion treatment. Table 3 reports the type and
quantity of addition for the organic polymers that were added to the conversion
treatment baths in both the invention examples and comparison examples.
Table 4 reports the type of lubricant top layer used after the conversion
25 treatment and the conditions for its application.
WO 94/16119 2 1 5 ~ 3 3 I PCI/US94/00212
Table 1
Type of Pretreatment and P,elreat",ent Conditions for the Test Materials
Metal Treated r,etreatment Conditions
Carbon steel 15 % HCI, 15 minutes immersion
Galvanized steel 0.3 % PL-Z, 5 seconds immersion
Stainless steel 10 % HNO3 + 4 % HF, 20 minutes immersion
Aluminum 30 % HNO3, 10 minutes immersion
Notes for Table 1
All the pretreatments were at ambient temperature. Water formed the
balance of the treatment compositions not stated: "PL-Z" means
PREPALENETM Z, a commercial product of Nihon Parkerizing Co., Ltd.
Table 2: Type and Conditions for the Base Conversion Treatment
No. TyPe Treatment Bath Treatment
Compositions Conditions
a Zn phosphate A PB-421WDM': 65 g/L 80 C, 8 minutes,
+ immersion
AC-1312: 0.3 g/L
b Zn phosphate B PB-3300M3: 45 g/L 60-C,8seconds,
immersion
c oxalate salt FBA-14: 40 g/L 90 C, 15 minutes,
+ immersion
FBA-25: 20 g/L
+
AC-165: 1 g/L
d fluoride ABA7: 30 g/L 93 C, 5 minutes,
immersion
.
WO 94/16119 2 ~ 3 ~ ~ PCT/US9410021?
Footnotes for Table 2
PALBONDTM 421WDM, a zinc phosphate conversion film forming agent
(for carbon steel)
2 ACCELERATORTM 131, an accelerant for conversion film forming reac-
tions
3 PALBONDTM 3300M, a zinc phosphate conversion film forming agent (for
galvanized steel)
4 FERRBONDTM A-1, a base for ferrous oxalate conversion film formation
(for stainless steel)
5 FERRBONDTM A-2, a promoter for oxalate conversion film formation
6 ACCELERATORTM 16, an accelerant for conversion film forming reac-
tions
7 ALBONDTM A, a zinc fluoride conversion film forming agent (for
aluminum)
Additional Notes for Table 2
All the product names with identifying footnotes are products of Nihon
Parkerizing Company, Limited.
The balance not shown for the Treatment Bath Compositions was water.
Table 3: Types of Organic Polymers Added to the Conversion Baths
Chemical Nature Molec-
ular
Weight
A adduct of NH(CH3)2 with bisphenol A-type epoxy resin 8,800
B copolymer of methyl methacrylate and 20 000
dimethylaminoethyl methacrylate
C adduct of H2NCH2N(CH3)2 with maleic anhydride resin 2,000
D adduct of H2NCH2N(CH3)2 with maleic anhydride resin 800
E polyvinyl alcohol 3,000
F polyacrylic acid 10,000
WO 94/16119 PCT/US94/00212
- 2153331
Note for Table 3
Nos. A, B, and C are for examples according to the invention, while Nos. D, E,
and F are for comparison only.
Table 4
Type of Lubricant Top Layer Used after Conversion Treatment and
Conditions for Its APplication
No. Type Treatment comPosition Treatment
Conditions
a dry soap COSHINTM No. 10' (calcium stearate soap powder)pre-die
application
b soap PALUBETM 46012 (sodium stearate soap base): 40 g/L 80~ C, 3
minutes,
immersion
c oil A NoxRusTTM-55oH3 roll squeegee
d oil B KOSAKUYUTM 6604 rollsqueegee
e resin organic polymerS: 50g/L rollsqueegee
Footnotes for Table 4
dry lubricant for wire drawing, product of Kyoeisha Yushi Kogyo Kabushiki
Kaisha
2 wet soap lubricant, product of Nihon Parkerizing Company, Limited
3 anticorrosion oil, product of Parker Kosan Kabushiki Kaisha
4 press oil, product of Nippon Kosakuyu Kabushiki Kaisha
5 resin sealant = No. B in Table 3
3. Treatment method
A lubrication treatment was executed on the test materials by the pro-
cess sequence given below. The water washes carried out after pickiing in the
WO 94/16119 PCT/US94/0021;~
2~L~333~
-
pretreatment step and after the conversion treatment consisted of immersion
for 1 minute in running tap water. Drying was carried out for 5 minutes in a hotair circulation oven at 100- C. Test materials were used that were free of
adhering oil.
5 Process Sequence: pretreatment ~ water wash (except for galvanized steel)
~ conversion treatment ~ water rinse ~ treatment with lubricant ~ drying.
4. Performance evaluation testing
The performance afforded by the lubrication treatments described above
was evaluated by the following test methods.
4-1. Evaluation of the seizure resistance
Using an EFM-4 Model of Bowden-Leben friction coefficient tester pro-
duced by Toyo Baldwin Kabushiki Kaisha, under conditions reported in Table
5, the following two parameters were evaluated: (1) the initial coefficient of
friction when sliding was initiated, and (2) the number of slides until seizure
15 (defined as a coef~icient of friction = 0.3).
Table 5
Pressure element: SUJ-2, 5 mm diameter sphere
Load: 5 kg
Temperature: 30 C
Slide length: 10 mm
Sliding velocity: 10 mm/sec
4-2. Wire drawing evaluation
The following two parameters were evaluated using a dry continuous
wire drawing machine produced by Miyazaki Tekko Kabushiki Kaisha and the
wire drawing test conditions reported in Table 6: (1) surface planarity ratio ofthe finished wire, and (2) the total quantity of drawn wire that met a finished
wire dimensional tolerance of + 1/100. The surface planarity is a parameter in-
dicative of the lubrication conditions during the wire drawing process. In gen-
12
WO 94/16119 213 3 3 31 PCT/US94/00212
eral, smaller values for the planarity ratio are indicative of a better lubrication.
Table 6
Wire sizes: parent wire diameter: 2.05 mm
finished wire diameter: 0.67 mm
Cross section reduction: 89.3 %
Number of dies: 10
Wire speed: 680 m/minute
0 4-3. Evaluation of tube drawing
The drawing force, core force, and the presence/absence of seizure
(indicative of drawing conditions) were evaluated using a chain type drawing
bench and the tube drawing test. conditions reported in Table 7. A lower
drawing force and lower core force are indicative of better lubrication.
Table 7
Drawing sizes: First pass: 46 mm diameter x 4 mm thick
to 42 mm diameter x 3 mm
thick (core draw)
Second pass: 42 mm diameter x 3 mm thick
to 37 mm diameter x 3 mm
thick (coreless draw)
Cross section reduction: First pass: 30 %
Second pass: 13 %
Total: 39 %
Drawing speed: 15 meters/minute
4-4. Evaluation of the pressability
The following two parameters were evaluated using a high speed deep
30 draw tester made by Tokyo Shikenki Seisakujo Kabushiki Kaisha [Tokyo Test
Equipment Mfg. Company, Limited] and the press testing conditions given in
Table 8: (1 ) the punch load for a draw ratio = 2.0 and a blankholding pressure
W O 94/16119 PC~r~US94/0021~
2 1~33~:1
of 3 tons, and (2) the critical blankholding pressure at a draw ratio of 2.3.
Lower punch loads and higher critical blankholding pressures are indicative of
a better lubrication.
Table 8
Blank size: 100 mm diameter (draw ratio = 2.0)
115 mm diameter (draw ratio = 2.3)
Punch size: 50 mm diameter
Punch shoulder: 5 mm radius
Die size: 52 mm diameter
Die shoulder: 5 mm radius
Punch velocity: 30 mm/minute
Temperature: 30 C
5. Results of the performance evaluations
Table 9 reports the results of the performance evaluations for the
working and comparison examples. The results in this table demonstrate that
the invention examples (numbers 1 to 12) gave a lubrication performance for
the various materials that was superior to the lubrication performance afforded
by the comparison examples (numbers 13 to 25).
- WO 94/16119 s ~ 1 ~ 3 3 3 1 PCT/I~S94/00212
Table 9: Results of the Performance Evaluations
Polymer
TreatmentPolymer Amount, Lubrication
No. Test Material TyDe TyDe WL) Type
carbon steel a A 5 a
2 carbon steel a B 5 a
3 carbon steel a C 5 a
4 galvanized steel b A 5 c
galvanized steel b B 5 c
6 galvanized steel b C 5 c
7 stainless steel c A 5 b
8 stainless steel c B 5 b
9 stainless steel c C 5 b
aluminum d A 5 b
11 aluminum d B 5 b
12 aluminum d C 5 b
13 carbon steel a none - a
14 carbon steel a D 5 a
carbon steel a E 5 a
16 carbon steel a F 5 a
17 carbon steel a none - e ~ a
18 galvanized steel b none - c
19 galvanized steel b D 5 c
galvanized steel b E 5 d
21 galvanized steel b none - e ~ c
22 stainless steel c none - b
23 stainless steel c F 5 b
24 aluminum d none - b
aluminum d D 5 b
Note for Table 9
With regard to the type of lubrication treatment for Comparison Examples
35 17 and 21, "e ~ a" and He ~ c" indicate that resin sealing ~e" was carried out
after conversion treatment and that this was additionally followed by lubrication
treatment"a" or"c".
(Table 9 is continued on the next page)
WO 94/16119 PCT/US94/0021~
2 1 ~ 3 ~ ~ 1
(Table 9 Continued from the previous page)
Seizure ResistanceWire Drawing Performance
Initial
CoefficientNumber of Slides Total Amount Surface
No.of Frictionuntil Seizure of Wire Drawn. Kg Planarity
0.11 977 3200 65
2 0.10 870 3100 68
3 0.10 825 2700 72
o 4 0.10 270 - -
0.12 280
6 0.12 215
7 0.11 260
8 0.12 320
9 0.12 365
0.11 160
11 0.10 140
12 0.12 185
13 0.13 265 1700 84
14 0.12 460 1900 78
0.11 350 2100 80
16 0.12 385 2000 81
17 0.12 585 2300 76
18 0.15 93
19 0.13 120
0.14 110
21 0.14 165
22 0.12 105
23 0.15 128
24 0.12 63
0.11 75
(Table 9 is continued on the next page)
WO 94/16119 215 3 3 31 PCT/US94/00212
(Table 9 is continued from the previous pageJ
- Tube Drawing Performance
5 Drawing Force,Core force, Evaluation
(Kglmm2) (Kg/mm2) of
No. 1st Pass 2nd Pass 1st Pass 2nd Pass Seizure
,o 3
7 38.2 19.7 2.26 coreless + +
8 37.8 18.8 2.05 coreless + +
9 39.3 20.7 1.85 coreless + +
11 - - - - -
12
13
14
16
17
18
19
21
22 46.4 25.8 4.86 coreless x
23 43.1 24.2 4.46 coreless +
24
(Table 9 is continued on the next page)
WO 94/16119 PCT~S94/0021'
53331
(Table 9 continued from the previous page)
No. Punch Load. Tons Critical Blankholding Pressure. Tons
4 4.63 2.0
4.54 1.75
6 4.58 2.0
0 7
11
12
13
14
16
17
18 5.68 < 0.25
19 5.34 < 0.25
5.15 < 0.25
21 4.86 0.75
22
23
24
Benefits of the Invention
A major improvement in lubrication properties--and particularly in the
seizure resistance--can be obtained by carrying out a lubrication treatment
18
WO 94/16119 215 3 3 31 PCT/US94/00212
after the formation of a composite fiim on a metal surface using the metal sur-
face treatment agent in accordance with the present invention. Specifically, theinvention makes possible in a single step an increase in such practical operat-
ing limits in metal cold working as the working degree or ratio, working speed,
5 tool life, and the like. The invention is therefore useful in terms of improving
productivity, product stability, cost reduction, and the like.
