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USOOS] 14607A
United States Patent [19] [11] Patent Number: 5,114,607
Deck et a1. [45] Date of Patent: May 19, 1992

[54] Low FOAMIXG ALKALIXE CLEANER 4.452.712 6/1984 Laemmle ......................... . 252/52 A
COMPRlSlNG A SURFACLAXT {\HXTURE 4.477.290 10/1984 Carro11 et a1. . .... .. 148/0
~ _ _ v ' '3 4.521.332 6/1985 MilOra .......... .. 252/5"?

253153535335;
' ' 53533.15;
' 4.599.116 7/1986 King et al. .............
........... .. . 134/40
[75] Inventors: Philip D. Deck. Ardsley; Jose B, 4.756.846 7/1988 Malsuura et a]. .. 252/173
Rivera, Philadelphia: wmiam L. 4.762.638 8/1988 Dollman et al. ...... .. 134/40
4.836.951 6/1989 TOtten ct a]. . 752/1742]
Hamel’ Langhome' a“ of Pa‘ 5.049.303 9/1991 Secenski ........................ . 252/1741:
l 73 1 Awgne?
I : BtLab
eZ Ora t ones
' .l ..T
nc re‘'ose.P.
a _
Primary Examiner-Paul Lieberman
[21] APPl- 90-1 555187 Assistant Examiner~Bradley A. Swope
P7] Filed. Aug 8 1990 Attorney. Agent. or Ft'rm—Alexander D. Ricci: Steven
" . ‘ ' ’ D. Boyd

[51] Int. Cl.5 ........................ .. CllD 7/06; C1 lD V66

(52] user. ............................. .. 252/156; 252/1742; [57} ABSTRACT
_ 252/174111 252/1351 252/1731 ZSZ/DIG- 14 A cleaning and etching solution and method for metal
158] new of Search --------- -~ 252/135- 156- 173' 174'21' surface is disclosed which is an alkaline formulation
252/l74'22' DIG‘ ‘4 which includes a surfactant combination ofa low foam
16]
s Ref9.
rem-e5 Cited 'ghl
11'] et 3' ene on‘d e - p ropy 1 ene on'dblk
e 0e ' co pl
0 ymer
L. S PATENT DOCUMENTS surfactant and a defoaming reverse ethylene oxide -
' ’ ‘ _ ‘ propylene oxide block copolymer. The preferred
1659875 9/1953 DVQTkm‘l‘Z ---------- ------------- -- 41/43 cleaner includes an alkali metal hydroxide. an alkali
2H9? 6‘ 31'1"“ ‘j'g'v'h?z/i'; metal salt of gluconic acid and preferably an alkali tri
Ioeivbt 9/1991 W: 252/55 pol-"phosphale and ‘he Surfaclam combina‘im
4.332.692 6/1982 Dayne et al. .. ..... . 252/17422
4.410.447 10/1983 Decker et al. ............... .. 252/l74.22 3 Claims, N0 Drawings
 5,114,607
1 2
present invention effectively removes dirt. debris. oil
LOW FOAMING ALKALINE CLEANER and fine metal particles from the metal surface. The
COMPRISING A SURFACTANT MIXTURE OF AN present invention is notably effective under heavy oil
EO-PO-EO BLOCK COPOLYMER AND A contamination loads without excessive foaming or
PO-ZO-PO BLOCK COPOLYMER waste treatment/handling problems. The present inven
tion comprises the addition of a low foaming ethylene
FIELD OF THE INVENTION oxide - propylene oxide (EO-PO) block copolymer
The present invention relates to the cleaning and surfactant and a defoaming reverse EO-PO block co
etching of metal surfaces to remove dirt. debris. oil and polymer surfactant to a cleaner comprising an alkali
?ne metal particles. More particularly. the present in metal hydroxide. an alkali metal salt of gluconic acid
vention pertains to alkaline cleaning and etching formu and preferably an alkali metal tripolyphosphate. Both
lations for metals in which a surfactant combination of surfactants effectively wet a metal surface being
a low foaming ethylene oxide - propylene oxide block cleaned. The water soluble surfactant provides deter
copolymer surfactant and a defoaming reverse ethylene gency while the oil soluble surfactant acts as a defoamer
oxide - propylene oxide block copolymer surfactant are 5 and aids in separation ofthe oil during waste ?uid treat
employed. ment.
The composition of the present invention may be in
BACKGROUND OF THE INVENTION the form of a powder or an aqueous suspension. The
Alkaline cleaning treatments are employed in a vari aqueous solution will include a hydrotrope to maintain
ety of metal forming and coating processes. In the pro- . the suspension. The method and composition of the
duction of steel. cleaning operations to remove oil and present invention provides for effective cleaning of
debris take place prior to annealing. galvanizing. plating metal surfaces even under heavy oil conditions due to
or coating. ln aluminum processing. cleaning operations the presence of the low foaming EO-PO block copoly
to remove oil and debris precede conversion coating or mer surfactant. The cleaning bath is resistant to foaming
other coating operations. Satisfactory treatment of such due to the presence of the defoaming reverse EO-PO
metals requires that any dirt and lubricants from the block copolymer surfactant. In addition. the defoaming
forming. drawing and ironing operations be removed. reverse EO-PO surfactant simpli?es separation of the
Alkaline and acid cleaners are employed in the metal waste oils from the aqueous treatment solution during
cleaning area. In the cleaning of aluminum. both alka effluent treatment.
line and acid cleaners have been employed. Acid etch
ing and cleaning with. for example. hydrofluoric acid DESCRIPTION OF THE PREFERRED
gives good results producing clean mirror bright sur EMBODIMENTS
faces. However. the use of acids for cleaning present The present invention is directed to a composition
safety and effluent disposal problems and also requires and method for use in cleaning and etching of metal
stainless steel equipment. For these reasons. alkaline surfaces. The cleaning solution of the present invention
cleaning and etching processes are favored in the alumi preferably includes an alkali metal hydroxide. an alkali
num processing industry. An alkaline cleaning and etch
metal salt of gluconic acid and preferably an alkali metal
ing process for aluminum is disclosed in US Pat. No.
tripolyphosphate. It was discovered that the addition of
4.477.290 to Carroll et. al. The low temperature alkaline
cleaning and etching solution for aluminum disclosed 40 a unique surfactant combination comprising a low
comprises alkaline metal hydroxides ‘and a chelating foaming EO-PO block copolymer surfactant and a de
agent at temperatures of from 80 to l30° F. No other foaming reverse EO-PO block copolymer surfactant
ingredients such as wetting agents which would cause will provide for lower surface tension thereby enhanc~
foaming problems are required. ing cleaning while also controlling foaming in the clean
US. Pat. No. 4.521.332 to Milora discloses a highly ing solution. The components of the surfactant combi
alkaline aqueous cleaning dispersion for strip steel nation are copolymer surfactants of the general for
which comprises sodium hydroxide. a bulking agent mula: (RO)—(R'O),,-(RO) for an EO-PO block co
such as sodium carbonate and a poly(acrylic acid) dis polymer and (R'O)—(RO),,—(R'O) for a reverse
persing agent. EO-PO block copolymer where R equals an ethylene
With prior art cleaning solutions. the accumulation of group and R’ is a propylene group and n is at least 5.
oils in the bath presents a three fold problem. First, the The ratio of the EO-PO surfactant to the reverse
presence of oils makes metal cleaning more difficult as EO-PO surfactant as well as the selection of specific
the capacity of the surfactants to emulsify oil from the commercial surfactants will be related to the speci?c
metal becomes limited. Second. in alkaline baths, the properties of the system being treated.
oils may saponify and thereby contribute to foaming. The cleaning solution of the present invention may
Third, subsequent treatment of the af?uent must sepa optionally include an alkali metal tripolyphosphate.
rate out the emulsified oils prior to discharge. Higher Preferably sodium tripolyphosphate is employed. Be
treatment levels of surfactants are often used to remedy cause of the concerns relating to phosphate discharge.
the problems of insufficient cleaning in the presence of "non-phosphate“ cleaning and etching solutions are
oils. However, this may result in an increase in foam 60 desirable in some areas. A “non-phosphate" cleaner in
generation and difficulties in breaking the oil/water accordance with the present invention would require
emulsion prior to discharge of the effluent. the selection of and balancing of ratios of the EOzPO
surfactants to reverse EOzPO surfactants unique to such
SUMMARY OF THE INVENTION a system. For example, the ratio of EOzPO to reverse
The present invention provides a composition and 65 EO:PO surfactant may need to be increased or, alterna~
method for cleaning metal surfaces such as aluminum, tively, surfactant of higher HLB values may need to be
cold rolled steel, galvanized steel and Galvalume (a employed to increase the cleaners detergency. Addi
trademark of the Bethlehem Steel Corporation). The tional sequesterants may also be necessary.
 5,114,607
3 4
The composition of the present invention may be hydroxide. soda ash. sodium tripolyphosphate. tris
supplied as a powder or as an aqueous solution. Typi doium phosphate. Plurafac D-25. Plurafac RA-ZO. Ter
cally. when supplied as an aqueous solution. the solution gitol MinFoam l-X. and Triton CF-76: E: Parco 8001
is a concentrate which is diluted in water to l to 6% by available from Parker-Amchem (Henkel Corp.) phos>
volume prior to use. When formulated as an aqueous phated. alkaline cleaner with ethoxylated surfactants.
solution. the composition includes a hydrotrope which Tergitol is a tradename for a series of nonionic and
increases the aqueous solubility of the surfactants. Suit anionic surfactants available from Union Carbide Corp.
able hydrotropes include sodium alkanoate such as Triton is a tradename for modi?ed ethoxylated surfac
Monatrope 1250 available from Mona Industries. A tants available from Rohm 8: Haas Co.
preferred aqueous concentration in accordance with the 10 TABLE I
present invention comprises in volume percent:
Cleaning Efficau (‘1 “BF on CRS)
Free ‘7} Oil
ll'lgl'cdwnl cl‘nccnlmllml Treatment Alkalinity 0.0 0.5 1.0
Water 55 to 05’? Li A 110 100 100 100
KOH (45¢) 20 to 30‘? B 13 4 9o Q5 85
Sodium tripoiyphosphate 3 to 10"? C 11:) 100 100 on
Gluconic acid (50'?) 2 to 5'7 D ml] 100 95 80
Monolrop 1250 3 to 10“: E 12o oq g5 15
Pluronic L43 and 0.5 to 3'7
Pluronic 31R—! 20
Table 2 summarizes foam height measurements for
Such a concentrate would be diluted to approxi the same compositions as in Table 1.
mately 1 to 671 in water. preferably 3'7? prior to use. TABLE 2
Pluronic L-43 is a low foaming EO-PO block copoly Foaming Propensm (height in cm!
mer surfactant while Pluronic 3lR-l is a defoaming - ‘.7 Oil
reverse EO-PO block copolymer surfactant. Both are Treatment 0.0 2.0
available from BASF-Wyandotte Corporation. The A 0.0 (1.0
Pluronic block copolymers are nonionic difunctional B 0.0 2.5
block polymers. They are polyoxyalkaline derivatives C 1.0 14.0
of polyethylene glycol. The selection ofthe ratio of low D 0.4 1.0
E 04 Z0
foaming to defoaming surfactant will depend upon the
speci?c conditions of the system being treated. Typi
cally the ratio will range from about 1:3 to 3:1. The Table 3 summarizes the results ofthe waste treatabil
concentration of the hydrotrope may have to be ad ity studies of the composition as in Table l in terms of
justed based on the ratio of surfactant to maintain aque clarity. oil recovery (parts per million) after acidi?
ous solubility. cation and oil recovery in parts per million after acidi?
The present invention will now be further described cation and lime plus flocculant treatment. Both acidi?
with reference to a number of speci?c examples which cation and acidi?cation plus lime/flocculant are known
are to be regarded solely as illustrative and not as re waste effluent cleaning operations.
stricting the scope of the invention. 40
TABLE 3
EXAMPLES Waste Treatabiliiy
Oil (ppmi
Determinations of cleaning efficacy. foaming propen Acidi?cation - Clarity
sity and waste treatability for a number of cleaning and Treatment Acidi?cation Lime/flocculant (nil)
etching solutions. including the preferred composition 45 A -— — 44
of the present invention were undertaken. Cleaning B 192 100 In
ef?cacy was determined by estimating the percentage C 4% 101 14
of water break free (‘72 WBF) surface on aluminum. D 3980 1530 ll
E 284 40 15
cold rolled steel. and hot-dipped galvanized steel. The
solution was spray applied at 125° F. for 5 seconds on 50
aluminum and galvanized steel and 10 seconds on cold As can be seen from Table l. 2 and 3, the preferred
rolled steel. The free alkalinity ofthe treatment solution composition (A) of the present invention provides im
in points was as shown. Foaming propensity was deter proved cleaning ef?cacy, with a low foaming propen
mined by measuring the foam height after 5 minutes sity and acceptable waste treatability. Treatments ofthe
bath circulation at 125° F. and 15 psi. Waste treatability prior art. B, C. D and E all exhibit a pronounced weak
was determined by measuring the clarity ofa column of ness in at least one of these areas.
the waste ef?uent in a graduated cylinder. The volume While this invention has been described with respect
in Table 3 is a minimum volume through which a mark to particular embodiments thereof, it is apparent that
on the bottom ofa graduated cylinder could be viewed. numerous other forms and modi?cations of the inven
Table ] summarizes a cleaning ef?cacy of A: the tion will be obvious to the skills of the art. The ap
preferred composition of the present invention as de pended claims and this invention generally should be
scribed above; B: a composition comprising sodium construed to cover all such obvious forms and modi?ca
hydroxide, sodium tripolyphosphate, soda ash, sodium tions which are within the true spirit and scope of the
gluconate. and a high ratio of Tergitol TMN-3 to Ter present invention.
gitol TMN-o; C: a composition comprising potassium What is claimed is:
hydroxide, sodium tripolyphosphate, gluconic acid, l. A cleaning solution for cleaning and etching a
Triton DF-20, and a low ratio of Tergitol TMN-3 to metal surface with an alkali treatment including an al
Tergitol TMN-b; D: a composition comprising sodium kali metal hydroxide and an alkali metal salt of gluconic
 5,114,607
5 6
acid. the improvement comprising including in said oxide block copolymer to reverse ethylene oxide - prop
cleaning solution the combination of a low foaming ylene oxide block copolymer is from about 1 to 3 to
ethylene oxide - propylene oxide block copolymer sur about 3 to l; and wherein the concentration of ethylene
factant of the structure (RO)—(R’O)”—(RO) and a oxide - propylene oxide block copolymer surfactant and
defoaming reverse ethylene oxide - propylene oxide reverse ethylene oxide - propylene oxide block copoly
block copolymer surfactant of the structure (R'O)—(‘ mer surfactant in the cleaning solution ranges from
ROM-(R'O) as the sole foam agents where R is ethyl about 0.005 to about 018 volume percent.
ene and R’ is propylene; wherein the ratio of ethylene 3. A composition for cleaning and etching a metal
oxide - propylene oxide block copolymer to reverse surface comprising an alkali metal hydroxide, an alkali
ethylene oxide - propylene oxide block copolymer is metal tripolyphosphate salt. an alkali metal salt of glue
from about 1 to 3 to about 3 to l; and wherein the con conic acid and a surfactant combination comprising a
centration of ethylene oxide - propylene oxide block low foaming ethylene oxide - propylene oxide block
copolymer surfactant and reverse ethylene oxide - prop copolymer surfactant of the structure (RO)—(R’O)
ylene oxide block copolymer surfactant in the cleaning ,,-—(RO) and a defoaming reverse ethylene oxide - prop
solution ranges from about 0.005 to about 018 volume ylene oxide block copolymer surfactant ofthe structure
percent. -
2. A method of cleaning and etching a metal surface (R'O)—(RO),,—(R'O) as the sole foam agents where R
with an alkaline cleaning solution comprising an alkali
is ethylene and R’ is propylene; wherein the ratio of
metal hydroxide and an alkali metal salt of gluconic ethylene oxide - propylene oxide block copolymer to
acid. the improvement comprising including in said 20 reverse ethylene oxide - propylene oxide block copoly
solution the combination of a low foaming ethylene mer is from about 1 to 3 to about 3 to l: and wherein the
oxide — propylene oxide block copolymer surfactant of concentration of ethylene oxide - propylene oxide block
the structure (RO)——)R'O),,—(RO) and a defoaming copolymer surfactant and reverse ethylene oxide - prop
reverse ethylene oxide - propylene oxide block copoly ylene oxide block copolymer surfactant in the cleaning
mer surfactant ofthe structure (R'O)—(RO)"—(R'O) as solution ranges from about 0.005 to about 0.l8 volume
the sole foam agents where R is ethylene and R’ is prop percent.
i it ‘ i #
ylene; wherein the ratio of ethylene oxide - propylene

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