DECAPANT DE PHOSPHATAGE, ET MODE D'EMPLOI CONNEXE

DETERGENT PHOSPHATIZER COMPOSITION AND METHOD OF USING SAME

Abrégé anglais

ABSTRACT OF THE DISCLOSURE

Room temperature detergent a liquid iron
phosphatizer composition for use in industrial metal
cleaning and spray washing applications, which also can
be heated to clean and phosphatize under heavy-soil load
conditions. The composition consists essentially of
from about 50 weight percent to about 94 weight percent
water, from about 5 weight percent to about 40 weight
percent phosphoric acid, from about 0.1 weight percent
to about 5 weight percent of at least one heavy metal
accelerator selected from the group consisting of
vanadium, titanium, zirconium, tungsten and molybdenum
compounds and from about 1 weight percent to about 20
weight percent of at least one oxidizer.

Revendications

The embodiments of the invention in which an
exclusive property or privilege is claimed are defined
as follows:


1. A liquid iron phosphatizing composition
which consists essentially of from about 50 weight
percent to about 94 weight percent water, from about 5
weight percent to about 40 weight percent phosphoric
acid, from about 0.1 weight percent to about 5 weight
percent of at least one heavy metal accelerator selected
from the group consisting of vanadium, titanium,
zirconium, tungsten and molybdenum compounds and from
about l weight percent to about 20 weight percent of at
least one oxidizer.


2. An iron phosphatizing composition as in
Claim l, wherein the oxidizer is at least one member
selected from the group consisting of chlorates,
bromates, iodates, nitrates, sulfites, nitrites, hydro-
gen peroxide, chlorites and organic nitro compounds.


3. An iron phosphatizing composition as in
Claim 1 which further contains caustic.


4. An iron phosphatizing composition as in
Claim 1 which further contains at least one nonionic
detergent of 0.5 to 15 weight percent.



5. A process for phosphatizing metallic
surfaces at solution temperatures of 60° to 130°F. which
comprises coating said metallic surfaces with an iron
phosphatizing composition consisting essentially of from
about 50 weight percent to about 94 weight percent
water, from about 5 weight percent to about 40 weight
percent phosphoric acid, from about 0.1 weight percent
to about 5 weight percent of at least one heavy metal
accelerator selected from the group consisting of
vanadium, titanium, zirconium, tungsten and molybdenum
and from about 1 weight percent to about 20 weight
percent of at least one oxidizer.


6. A process for treating metallic surfaces
at a solution temperature of 60° to 130°F. which com-
prises the steps of cleaning and phosphatizing the
metallic surface with an iron phosphatizing composition
consisting essentially of from about 50 weight percent
to about 94 weight percent water, from about 5 weight
percent to about 40 weight percent phosphoric acid, from
about 0.1 weight percent to about 5 weight percent of at
least one heavy metal accelerator selected from the
group consisting of vanadium, titanium, zirconium,
tungsten and molybdenum and from about 1 weight percent
to about 20 weight percent of at least one oxidizer,
rinsing the cleaned and phosphatized metallic surfaces
with water and applying a chromic acid rinse.

11



7. A process as in Claim 6, wherein the
cleaning and phosphatizing step and the chromic acid
rinse step are automatically monitored to insure the
maintenance of uniform concentrations of the active
ingredient in the coating solutions being used.


8. A metal treating process comprising an
alkaline cleaning step, a rinse step, a phosphatizing
step at a solution temperature of 60° to 130°F. which
utilizes an iron phosphatizing composition which
consists essentially of from about 50 weight percent to
about 94 weight percent water, from about 5 weight
percent to about 40 weight percent phosphoric acid, from
about 0.1 weight percent to about 5 weight percent of at
least one heavy metal accelerator selected from the
group consisting of vanadium, titanium, zirconium,
tungsten and molybdenum and from about l weight percent
to about 20 weight percent of at least one oxidizer, a
further rinse step and a chromic acid rinse step.


9 A process as in Claim 6, wherein the
cleaning, phosphatizing and chromic acid rinse step are
automatically monitored to insure the maintenance of
uniform concentrations of the active ingredient in the
coating solutions being used.

12

Description

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" ~ETERGE~T I~ON PHOSPHRTIZER COMPOSI~O~
AND METHOD OF USING SAME"



This invention relates to a composition and
process for cleaning and phosphatizing metals prior
to painting.

More particularly, this invention relates to
a composition and process for cleaning and phospha-
tizing metals which substantially reduces the energy
requirements of the cleaning and phosphatizing pro-
cess.

Both iron and zinc phosphatizing processes are
utilized to impart a crystalline phosphate layer to
metal surfaces in order to improve paint adhesion
and corrosion resistance. While phosphatizing pro-
cesses nave been wid~ly used in the past, their use
has been accompanied by a number of ~actors such as
1~ the requirements for high operating temperatures,
high energy costs and o~er-phosphatizing due to over-
activation by heat.


~?

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These disadvantages are overcome by the compo-
sition and process of the instant invention, in which
a heavy metal accelerator and an oxidizing agent are
added to an iron phosphatizing composition to permit
improved coating ability at reducea operating temper-
atures. Suitable oxidizing agents include bromates,
chlorates, iodates, sulfites, nitrates, nitrites,
hydrogen peroxide, chlorites and organic nitro com-
pounds. The compounds used most frequently are the
chlorates.

As used herein, an iron phosphatizing composi-
tion and process is distinguished from a zinc phos-
phatizing composition and process in several ways.
Iron phosphatizing compositions contain no zinc,
when applied have a thin amorphous structure and are
applied at coatweights oflO to 90 mg~ft. while zinc
phosphate coatin~ compositions contain zinc ~s an
essential ingredient, when applied have a relatively
heavy, definite crystal structure and are applied at
coatweights of 100 to 1000 mg/ft.2.

~ eavy metal accelerators useful in the composi-
tions of the instant invention include compounds of
such metals as vanadium, titanium, zirconium, tungs-
ten and molybdenum. The compounds utilized most
frequently are the molybdates.

The molybdenum compounds promote the phosphate
action on the surface of metals by seeding or plating
out on the surface, and then incorporating themselves
as l~wer oxides of molybdenum with the iron phosphate
3~ which ~orms in the reaction. ~owever, the mo~y~denum

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comes out in the form of oxides rather than the
metal, and leads to a supplementary protective non- -
corrosive coating. Although applicant does not wish
to be bound by theory, it is believed that the chem-
ical plating, precipitating or coating reaction inthe absence of heat is as follows:

I. 2Fe + 4H -~ 2Fe + + 2H2~

II 2~ + 4MoO~ + ~H~ oxidizer~ 2Mo205~+ 2H20 +

4H20

III 2Fe + 2MoO4 + 6H ~ Mo20~ + 2Fe + 3~2

IV. 2Fe + 2PO4--~2FePo4~
2FePO4 + 3M2s
V 2Fe + 6MoO4 ~ 18H + 2PO4 ~ Coating

9H20

The detergent iron phosphatizer composiitons of
the present invention may be applied by ccnventional
immersion or spray processes. Typical processes which
may be used include a three-stage process which com-
prises a cleaning and phosphatizing step, a water
rinse step and a chromic acid or non-chromic acid
rinse step. Non-chromic acid containing rinse for-
mulations such as sodium nitri~e or organic chelating
agents may be used where it is ecologica~ly desirable
to eliminate chromium from a~ueous discharges. Better
phosphate coatings may be obtained by using a ~ive-
stage process which comprises an alkaline cleaningstep, a rinse step, a phosphatizing step, an addi-
tional rinse step and a chromic acid or non-chromic

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acid rinse step. The five-stage process permits the
application of a more uniform phosphate coating. As
previously stated, an advantage of the composition
and p~ocess of this invention is the ability to oper-
ate efficiently at reduced temperatures. Best re-
sults are obtained at temperatures of 60 to 130~. as
opposed to conventional operating temperatures of 140
to 160~F.

~oth the three- and fi~e-stage process may be
controlled manually or automatically. Automatic con-
trol is, however, preferred because it permits more
accurate control of the concentration of the coating
compositions, thereby resulting in a more uniform
coating on the metal surfaces being treated.

The compositions of the present invention may
be prepared by conventional liquid or powder blending
techni~ues.

The liquid iron phosphatizing compositions of
the present invention do not contain zinc and con-
sist essentially of:

_ mponentAmount (Wei~ht Percent)
Water 94 to 50
Phosp~oric Acid 5 to 40
~eavy Metal Accelerator0.1 to 5
25 Oxidizing Agent 1 to 20

These compositions may also contain ca~stic to con-
trol p~ and from about ~.5 to about 15 weight percent
of a nonionic detergent if it is desired to use a
detergent phosphatizer composition in a three-step
process which combines the cleaning and phosphatiæing

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steps,

The preferre~ compositions consist essentially
of fro~ about 45 to about 85 weight percent water,
from about 10 to about 40 weight percent phosphoric
acid, from about 0.5 to about 2 weight percent of
at least one heavy metal accelerator, and from about
3 to about 10 weight percent of at least one oxidizer.

The solid powder phosphatizing compositions of
the present invention consist essentially of:

_ mponent Amount (Weight Percent)
Mono Sodium Phosphate 25 to 85
~eavy Metal Accelerator 0,1 to
Oxidizing ~gent 1 to 50

The preferred oxidizing agent is a blend of a
1~ chlorate and a nitrate and these compositions may
also contain from about 0.5 to about 15 weight per-
cent of a nonionic detergent. The preferred powder
coating compositions consist essentially of from
about 40 to about ~0 weight percent mono sodium
2~ phosphate, from about 0.5 to about 2 wei~ht percent
of at least one heavy metal accelerator an~ from
about 30 to about 50 weight per~ent of at least one
oxidizer.

~he compositions of the present invention may
be use~ in spray or immersion processes in concen-
trations of at least 1 oz./gallon of water and pre-
ferably at least 3 oz./gal10n of watex.

T~e following examples are representative of

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the compositions of the present invention:

EXAMPLE 1
ComponentAmount (Weight Percent)
Water 73
5 75% Phosphoric Acid15
Sodium Chlorate 3
Sodium Molybdate
Nonionic Detergent 8

EXAMPLE 2
ComponentAmount (Weight Percent)
Water 41.5
75~ Phosphoric Acid 35
Sodium Chlorate 10
Sodium Molybdate
15 Sodium Nitrate 5
Sodium Hydroxide 7.5

EXAMPLE 3
ComponentAmount (Weight Percent)
Water 50
20 75% Phosphoric Acid35
Sodium Molybdate 2
Sodium Nitrate 5
Sodium Nitrite 0.5
Sodium Hydroxide 7.S

EXAMPLF 4
-
ComponentAmount (Weight Percent)
Water 40
75% Phosphoric Acid 35
Sodium Chlorate 10
30 Sodium Nitrate
Sodium ~ydroxide 7.5
Sodi~m Meta~anadate 2.5

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EXAMPLE 5
Component Amount (Weight Percent)
Sodium Chlorate 5.0
Sodium Molybdate 0.5
5 Nonionic Detergent 4.5
Sodium Nitrate 45
Mono Sodium Phosphate 45

EXA~LE 6

This example demonstrates the synergistic ef-
fects of the use of sodium molybdate (heavy metal
accelerator) in combination with sodium chlorate
(oxidizer~, which improves the phosphate coating
ability of the formulation at reduced operating tem-
peratures.

Formulation Data:
Formula
Material A B C D
Water 58% 61% 59% 62%
Sodium Chlorate 3~ --- 3~
Sodium Molybdate 1~ 1% --- ---
75% Phosphoric Acid15% 15% 15~ 15%
50~ NaOH 5% 5% 5~ 5
~onionic Detergent12% 12% 12% 12
Hydrotrope 6% 6~ 6~ 6

Procedure:

Formulations containing the above combination
as well as each indi~idual component and a control
were prepared in the la~oratory as given in the for-
mula description abo~. Four hundred fifty (4~0~
grams of each material (A, B, C and D) was added to
five gallons of hot water (3 oz./gallon) which was

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allowed to spray continuously at 15 PSI without addi-
tional heat, during which time Triplicate R-35 "Q"
panels were placed in the spray for two minute inter-
vals at various temperatures as the solution cooled.
The panels were spray water rinsed and immediately
dryed and wrapped in foil for coating weight evalu-
ation, The spray washer was thoroughly rinsed be-
tween each process. The operating temperature was
measured immediately after processing each series of
panels.

Results:

TABLE I

Temperature Average Coating Weight
Form. Series (C.)(mgs/ft.~)
A A4 23.0 17.44
A 1 25.0 16.80
A 2 28.0 19.20
A 3 30.0 24.32
A 4 34.5 24.48
A 5 40.5 25.g2
A Al 48.0 32.32
B 4 24.0 14.40
B 3 30.0 14.72
B 2 36.0 22.56
B 1 41.0 26.24
2~ C 4 23.0 7.84
C 3 29.0 14.88
C 2 35.0 15.~2
C 1 49,0 17.92
D 6 26.0 10.50
~ 5 27.0 14,00
~ 4 30.5 13.20
D 3 35.0 14.70
~ 2 37.5 14.20
D 1 43.0 15.50

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Table I clearly demonstrates the improved
coating weights obtained with the compositions of
the present invention.