Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
3~
The present inven-tion relates to antirust treat-
ment of steel stocks or materials such as hot-rolled pickled
steel plate, cold-rolled steel plate and cast iron.
Usually surEace treatment is applied to the surface
of cold-rolled steel plates, etc. for anticorrosion and
preserva-tion of fine appearance.
That is, because a considerable time passes before
such various types of steel plates and so on are processed
and used, they are coa-ted with an an-tirust oil or chemically
treated or are packed in vaporable antirust paper or are
otherwise treated to prevent rust. Any of these prior art
methods for anticorrosion, however, has -the following draw-
baclcs.
The application of antirust oil will incur, not to
mention stickness of oil, the necessity for a degreasing step
when the s-teel plates are in use, followed by the -treatment
of the exhausted degreasing solution which is troublesome.
In addition, welding or like processing of materials
with antirust oil applied thereto presents problems in that
the electrodes become dirty, fuming becomes significant and
the preservation of a good working circumstances is adversely
aEfected.
Already known water soluble an-t:Lrust agents, Eor
example, sodium nitrite, sodium borate, aromatic carboxylic
acids, imidazoles, amines and surfac-tants are used alone or
in combination. }lowever, -their antirust effect is useful
rnainly in water or in -the air, and is rather poor when the
steel pla-tes contact one another in a wet atmosphere or under
conditions where water is attached to them or when they are
stacked at high temperature and high humidity~ namely, in a
wet box as specified by JIS 2-0228. Further, there are
\, ~ .
~8'~3~36
antirust agents with higher aliphatic amines or higher fa-tty
acids incorporated therein. However, they also have draw-
backs that their drying characteristics are bad and that a
removal s-tep is required as in the case of -the use of anti-
rust oil.
The inventors have already discovered that l-hydroxy-
benzotriazole has an excellent antirust effect for steel
stocks as is descri~ed in Japanese patent publication No.
27694/78. However, it has been found that there is in this
case a weakness tha-t the discoloration or staining is produced
in some cases if water is dropped on a treated steel pla-te,
and another treated one is stacked thereon and allowed to
stand at high temperature and high humidity atmosphere,
lS although their antirust properties are very excellent after
they are subjected to hot-air drying.
The present invention has overcome these draw~
backs of the prior art methods and has further made it pos-
sible to exert an extremely good antirust effect withoutnecessity for any further treatmen-t in the subsequent steps.
In summary, the present invention is characterized
by adjusting an aqueous solution of l-hydroxybenzotriazole
and an aliphatic dicarboxylic acid to within a neutral range
with a neutralizing agent and applying the ad~usted solution
to the surface of metals to form an antirust coating.
The effects of the present invention are not llmi-
-ted to antirust ones in a particular environment. The anti-
rust eEfPcts are excellent not only in water and in the air,
and in an acidic atmosphere or in an atmosphere of high
temperature and high humidity where water droplets are present
between the contacted treated steel plates or in other var-
ious environments where a temper rolling solution is scatteredor its vapor attaches as water droplets on steel plates
r
36
rolled in a high speed temper rolling step.
According to the present invention, a mixed aqueous
solution consisting mainly of a l-hydroxybenzotriazole com-
pound represented by -the general formula:
~ N
X~
~`/\ ~ /
OH
where X and Y represent hydrogen atoms and hydroxy, alkyl,
carboxyl, ni-t:ro and sulfonic groups, and containiny simul-
taneously an alipha-tic dicarboxylic acid, Eor example, one
~5 or more o:E suberic acid, azelaic acid and brassylic acid, is
neutralized with ammonia water, hydrazine or an alkanol amine
such as monoethanol amine ortrie-thanol amine to provide an
aqueous solution having a pH within the range of 7-11 which
is applied to steel stocks. The aqueous soluti.on may be
20 used after a water-soluble high molecular compound or a
surfactant is added there-to. Further, the object may be
attained by applying to the surface of s-teel stocks a solu-
tion ob-tained by adding the mixed aqueous soluti.on to an
emulsi.on such as an aqueous mixture of cutting oil, abrasive
~5 oil or rolling oil, whereby an antirust coa-tincJ is forrned.
In this instance, the concentration of -the l-hydroxyben-
æo-triazole of the above general formula and its de.r:i.va~::i ves
corltained in -the resulting solution is within the :rar~c3* o:E
0.01-10~ used herein is by weight), and the aliphatic
3() clicarboxylic acid added thereto may be empl.oyed within -the
ran~e oE 0 . 01 -5~, . Particularly pre:Eerabl.y, each of the ].-
hyc~roxybenzotrl.azole, main component, and the aliphatic di-
carboxylic acid, additive, is used i.n the range of 0.1-2
from the standpoint of the antirust and economic aspects.
35 Further, a proportion of 0.001-0.5~ for the surfactant if
added and a proportion of 0.01-2% for the high molecular
..~
compound if added arepreferred from viewpoints of antirus-t
and uniformity of the resulting coating, which will contri-
bute to the enhancement of the anticorrosive properties.
It is a characteris-tic feature of the present in-
ven-tion that direct painting or direct plating is possible
to the surface of steel stocks trea-ted according -to the pre-
sent invention, which exer-ts effects equivalent to those of
cases where painting or pla-ting is applied to the surface of
metals not subjected to any treatment.
The presentinvention will be further illustrated
by way of the following Examples.
1.5 Example l
._ _
An aqueous solution con-taining 0.5% of l-hydroxy-
benzotriazole and 0.3% of azelaic acid was adjusted to pH 8
by the addition of monoethanol amine as the neu-tralizing
agent to give a treating solution. A steel material was
subjected to the conventional -temper rolling, and water was
purposely applied to a part of the steel material at the
exlt, which was coiled as it was.
L,xample 2
An aqeuous solu-tion prepared by adding 0.2~ of
az~laic acid and Eu.rther 0.03~ of a nonionic surfactant (a
pol.yoxyethylene alkyl ether) to 0.4~ of l-hydroxybenzotria-
zole is adjusted to pH 8 by the addition o:E monoethanol amine
as the neutrali.zing agent to give a
4 -
treating solut;on. This treating solution is sprayed continuously over
a surface-cleaned cold-rolled steel plate. Immediately thereafter, the
plate ;s treated with rubber rolls and dried with a drier.
Example 3
An aqueous solution prepared by adding 0. 3% of sebacic acid
and 0. 1% of an acrylic resin, a water-soluble high molecular material,
to 0. 4% of l-'hydro~ybenzotriazole is adjusted to pH 8 by the addition of
triethanolamine as t'he neutralizing agent to prepare a treating solution.
This treating solution i5 sprayed continuously over a surface-cleaned
10 cold-rolled steel plate~ and immediately the plate is treated by rubber
rolls and driecl with a drier.
The results of a}~t~S~3 tests using steel plates treated accord-
ing to the above method of the present inven'tion and controls are shown
in Table 1, and the results of direct painting, in Table 2.
15 Example 4
~n aqueous solution prepared by adding 0. 2~/o of sebacic acid
and 0. 03'10 of a nonionic surfactant (a polyoxyethylene alkyl ether ) to
0, 5% of 1-hyclroxybenzotriazole is adjusted to pH 9. 0 by the addition
of monoethanol amine as the neutralizing agent to give a treating
20 solution. This treating solution is sprayed continuously over a sllrface~
cleaned cold-rolled steel plate. Immediately t'hereafter~ t`he plate is
treated with rubber rolls and dried with a drier.
E~cample 5
~n aqueous solution prepared by adding 0. 2% of a~elaic acid,
Z5 0. 1% of sebacic acid and 0. 05% of a polystyrene-maleic acid copolymeric
resin which is a water-soluble high molecular material, to 0. 5% of 1-
hydroxybenzotriazole is adjusted to pH 10. 5 by the addition of isopropanol
-- 5 --
~;Z3~3~
amine as the neutralizing agent to give a treating solution. It is
sprayed continuously over a surface-cleaned cold~rolled steel plate.
Immediately thereafter, the plate is treated with rubber rolls and
dried in air.
Table 1 Results of antirustic tests
Housin~ test in wet box* Indoor _
\ Stacked Stacked In 0~ 6 N
\ Stacking after after HC 1
\ drop- drop- exposureatmosphere
\ condi- ping of ping of for lO for 2
\ treating tap hours
\ tion s olution watcr da
_ _ \ (1 ) 1~_ ys (3 )
C oiled
and al-
~ Example 1 lowed to _ _ ~) (~3
o stand in
.~ plant for
~ l m onth _ _
2 0 d Example 2 _ _ _ _ _¦
~ Example 3 (~) (~) (~3 (~) (~
h _ l _, , . _ . ._
P~ Example 'L (~) (~3 (~) (~) (~)
_ . . _ _
__ Example 5 ~) ~) (~) _
Ammonium 0 0 ~ X X
2 5 g ebac at e , , l l l _
T riethanol
ami ne 0 0 ~ X X
~ azelate _ _
,~ 1 ~hydroxy ~
h benzotriazole (~) (~) ~~ O 0 O
~1 ammonium _ _
C ommer cially
available 0 0 ~ X X
~roduct A _~ _
.,
_ No treatment X X , X X X X X X X X
~ 6 --
1~8~3~
In the table,
* ... ....Ten test pieces of lO x 10 cm subjected to a seven day hous-
ing test in a wet box (50C, 98% RH) were bound tightly by the
use of a miniature vise and then subjected to the tests.
*~ ,The concentration of all the treating solutions used as the
controls was 1%, and the treatment using them was made by the
sa~ne procedures as in the case according to the present invention.
(1 ): The aqueous treating solution was dropped on the
treated steel plates, and the treated steel plates were stacked for
the tests. Discoloration and rust condition of the portions on w'hich
the solution was dropped were evaluated. I
(2 ) Tap water was dropped on the treated steel plates, and
t'he treated steel plates were stacked and tested. Rust condition
of the portions on which the water was dropped was evaluated.
(3 ): In the bottom of a desiccator, there was placed a 0. 6 N
aqueous HCl solution, and the treated steel plates were placed on a
perforated plate in the desiccator followed by the capping. Rust
condition after 24 hours was evaluated.
` , ,(4 ): The commercially available product A was of sodium
~`~ h ~ æ
~" 20 ~ t~ system.
Evaluations- ~) ... No change; O ... Slig'ht
discoloration; ~ ... Rust is noticeable; X ... ~bout 10~70 rust;
X X . . . ~bout 30% rust; X X X. . . More than 60% rust.
~23B6
Table 2 Direct painting properties
Primary ~ r- Secondary
~ . adhe s ion ( 1 ) adhe sion (2 )
-- \ _pr ope rtie s pr ope rtie s
5Treated steel plates
in Examples 1-3 of 10 lO
_he present invention _ __
Material treated with
commercially availa- 9 7
10_ ble product A __
Untreated material 10 10
-
*Paints used...... Acrylic and epoxyurea paints
(1): Cross-cut Ericksen 7 mm, unit 2 mm.
The coating was peeled off by the cellophane tape, and the
15 evaluation was made on the basis of ease of peeling.
(2 ) Adhesion properties of the coating were tested immediately
after ~he sample used in the primary adhesion test was imrnersed in
deionized water at 40C for 24 hrs,
The test items are the same as in the primary adhesion test.
Evaluations~ 10 (Excellent) - 0 (Failure)
I
-- 8 --
-
3~3~
Thus, according to the present invention, no-t only
the intended antirust effect can be fully displayed in var-
ious surrounding conditions but also no work in removing the
an-ticorrosive agent before the next step is necessary, and
painting or other required treatment.s may be conducted
directly, so the workability can be improved. Further, a
problern of toxicity resulting from the trea-tment has recently
arisen in the case of the conventional treatment involving
the use of sodium nitrite, whereas in case of the present
invention, such toxicity is ext.remely low, and in the weld-
ing or like operations, there is no environmental pollution
caused by fuming, nor any lowering of workability caused by
staining of the elec-trodes. Thus, the present invention
has excellent advantages as compared with the conventional
sur:Eace l:rea-tment methods.
~5
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