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Description  |
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This invention relates to viscous liquid hydrogen peroxide bleaches
containing a surfactant for laundry applications, where the viscosity of
the solution and its active oxygen content can be stable for long periods
of time.
Six percent hydrogen peroxide bleaches have been sold for many years for
use in the home to remove stains from laundry. Some of the products in
commercial use also contain a surfactant which increases the ability of
the bleach for penetrate and remove the stain and improves the overall
cleaning performance. The use of such products at the recommended level of
about one-half cup to a top loading washing machine, gives an available
oxygen concentration of about 60 ppm in the wash solution. The bleach
described herein may be applied directly to the stain and the viscosity is
such that it remains on the area to which it is applied, whereas current
products are so thin that they run off.
Aqueous gels of hydrogen peroxide are known and have found use as a hair
bleach, as an antiseptic, and in other applications. Preparations of
stable hydrogen peroxide gels containing up to 15% hydrogen peroxide are
described in U.S. Pat. No. 3,499,844. It was generally accepted, however,
that surfactants tend to destroy the structure of an aqueous gel and prior
to the present invention, care was taken to exclude surfactants when
formulating aqueous gel systems because substantial amounts of a
surfactant were known to break down the gel.
It has now been discovered that it is possible to manufacture stable
viscous solutions of hydrogen peroxide having a hydrogen peroxide
concentration of up to 30% and preferably about 3 to 8% in the presence of
a surfactant. Such compositions may be applied directly to stubborn stains
and are exceedingly effective because the viscous liquid does not run off
the stain which is subjected to high concentration of hydrogen peroxide in
the presence of a surfactant. Moreover, the thickener employed to obtain
the desired viscosity is a dispersant and this property is believed to
improve the overall performance in the washing machine.
It is most important that the viscosity of the bleach solution be constant
with time and that available oxygen is not lost during storage. This can
be achieved only through very careful choice of the thickener for the
aqueous system, the surfactant, and the order of mixing. As will be
further described below, the hydrogen peroxide compositions of the present
invention contain at least three other ingredients (1) a thickener to
impart the desired viscosity; (2) a neutralizing agent to insure a pH
where the thickener is effective; and (3) a surfactant that does not
destroy the structure imparted by the thickener. Optionally, the hydrogen
peroxide composition of the present invention may contain additional
components such as a dye or pigment, an opacifier, a perfume, an organic
solvent and an optical brightener.
In accordance with the present invention, a stable viscous aqueous hydrogen
peroxide bleach is prepared by adding about 0.5% to 4% of certain anionic
or nonionic surfactants to an aqueous hydrogen peroxide solution and then
thickening the solution of hydrogen peroxide and surfactant with a water
dispersible copolymer of an alpha-beta monoolefinically unsaturated lower
aliphatic carboxylic acid crosslinked with a polyether of a polyol
selected from the class consisting of oligo saccharides, reduced
derivatives thereof in which the carbonyl group is converted to an alcohol
group and pentaerythritol, the hydroxyl groups of said polyol which are
modified being etherified with allyl groups, said polyol having at least
two allyl groups per polyol molecule, by adjusting the pH to the desired
range. Examples of commercially available members of this class of resin
are the CARBOPOL resins, i.e., CARBOPOL 934, CARBOPOL 940 and CARBOPOL
941, manufactured by B. F. Goodrich Chemical Company, Akron, Ohio.
Particularly preferred because of its visual brightness and clarity is
CARBOPOL 940.
The basis reagent used to increase the pH of the CARBOPOL solution, and
adjust the viscosity, must not react with hydrogen peroxide. Sodium
hydroxide is a satisfactory neutralizing agent, triethanol amine is not.
The CARBOPOL resins are believed to be unique in that other commercially
available thickeners evaluated for increasing the viscosity of aqueous
hydrogen peroxide solutions either did not thicken the solution or lost
viscosity within a few days. The effectiveness of commercially available
thickeners in increasing the viscosity of the hydrogen peroxide solutions
of the present invention is illustrated by Example I and summarized in
Table I.
Another unique and unexpected aspect of the present invention is the
surfactant that can be incorporated in the viscous aqueous hydrogen
peroxide system without loss of available oxygen or destroying the viscous
flow charteristics of the solution. Cationic surfactants, such as the
quaternary ammonium salts, are incompatible with the anionic CARBOPOL
polymer. Derivatives of polyoxyethylene or polyoxypropylene that would
react with hydrogen peroxide, for example, mercaptans or amines, are not
suitable for use in the compositions of the present invention. Those
surfactants that do not adversely effect the solution viscosity or
available oxygen upon long storage are:
(1) alkali metal alkyl sulfates; i.e., sodium lauryl sulfates;
(2) linear alkylaryl alkali metal sulfonates;
(3) straight chain primary aliphatic ethoxylated alcohols having a melting
point above room temperature; and
(4) block copolymer polyols:
(a) characterized by a hydrophilic lipophilic balance value determined by
the method of Becher & Birkmeier, J. Am. Oil Chem. Soc. 41, 169 (1964) of
about 30.5 and a molecular weight of about 4,750; said block copolymer
polyol being obtained by adding poly(oxyethylene) groups to a
poly(oxypropylene) chain having a molecular weight of about 950;
(b) characterized by a hydrophilic lipophilic balance value of about 24 and
a molecular weight of about 7,500; said block copolymer polyol being
obtained by adding poly(oxyethylene) groups to a poly(oxypropylene) chain
having a molecular weight of about 2,250;
(c) characterized by a hydrophilic lipophilic balance value of about 13.5
and a molecular weight of about 4,585; said block copolymer polyol being
obtained by adding poly(oxyethylene) groups to a poly(oxypropylene) chain
having a molecular weight of about 2,750;
(d) characterized by a hydrophilic lipophilic balance value of about 15 and
a molecular weight of about 6,500; said block copolymer polyol being
obtained by adding poly(oxyethylene) groups of poly(oxypropylene) chain
having a molecular weight of about 3,250; and
(e) characterized by a hydrophilic lipophilic balance value of about 22 and
a molecular weight of about 13,333; said block copolymer polyol being
obtained by adding poly(oxyethylene) groups to a poly(oxypropylene) chain
having a molecular weight of about 4,000.
Example II evaluates a large number of commercially available surfactants
in viscous aqueous hydrogen peroxide systems from the standpoint of
shelf-stability. The effect of varying the amount of surfactant upon
solution viscosity is summarized in Table III.
The hydrogen peroxide employed in preparing the stable viscous solutions of
the invention may be derived from any source, for example, from the
electrolytic process, organic processes such as the anthraquinone process
or the like. The concentration of the hydrogen peroxide may be as high as
30% or may be that which is used as a liquid laundry bleach, namely, up to
about 15% by weight, and preferably 3 to 8% by weight. It is apparent that
in diluting the hydrogen peroxide distilled, deionized or other purified
water should be used in order to avoid introduction of metal ions or other
contaminants which decompose hydrogen peroxide. Likewise, stability of the
hydrogen peroxide may be improved by incorporation of known stabilizers,
for example, phenacetin, acetanilide, 8-hydroxyquinolene, the methyl ester
of p-hydroxybenzoic acid or other known stabilizers in the amount of a few
hundred parts per million, or more. Such stabilizers are present in some
commercial products.
The thickening resins employed in the present invention are described in
U.S. Pat. No. 2,798,053, and are copolymers of a water dispersible
copolymer of an alpha-beta monoolefinically unsaturated lower aliphatic
carboxylic acid crosslinked with a polyether of a polyol selected from the
class consisting of oligo saccharides, reduced derivatives thereof in
which the carbonyl group is converted to an alcohol group and
pentaerythritol, the hydroxyl groups of said polyol which are modified
being etherified with allyl groups, said polyol having at least two allyl
groups per polyol molecule which are readily dispersible in water. A
suitable copolymer is one of acrylic acid with low percentages (0.75 to
1.5%) poly allyl sucrose. The poly allyl sucrose preferably contains about
5-8 allyl groups per sucrose molecule, and can be prepared in accordance
with Example I of the indicated United States patent; a suitable copolymer
can be prepared in accordance with Example II of the patent.
An example of a specific product so prepared is that designated by the
trademark "CARBOPOL 934". This product is a colloidally water-soluble
copolymer of acrylic acid crosslinked with approximately 1% by weight of
an allyl sucrose, the latter material having an average of about 5.8 allyl
groups per molecule. This product is prepared by mixing the acrylic acid
monomer and the allyl sucrose in the presence of a toluene diluent and 1%
of benzoyl peroxide and allowing the reaction to proceed to completion.
Upon completion, the diluent, together with unreacted monomer and
catalyst, is removed by filtration and subsequent volatilization from the
solid polymeric residue. The polymer thereby obtained is in the form of
light powder having a maximum particle size of 10 mesh and a bulk density
of about 12 pounds per cubic foot. The exact molecular weight is of course
unknown, but analysis shows that the product has an equivalent weight
(molecular weight per repeating unit) of about 77. The minimum molecular
weight, as roughly determined from viscosity measurements is probably
about 200,000.
Addition of sodium hydroxide to a dispersion of CARBOPOL resins in the
presence of specific surfactants results in the formation of a viscous
aqueous liquid having pseudoplastic properties. Typically, these solutions
have viscosities in the range of 60 cps to 6,000 cps, as measured with the
Brookfield Viscometer, Model LVT, #3 spindle at 6 r.p.m.
The specific surfactants that may be employed in the composition of the
present invention are usually present in amounts of from about 0.5 to 4%
by weight. As the amount of surfactant is increased above 4 weight
percent, the viscous hydrogen peroxide solutions may lose clarity and
become cloudy.
The amount of CARBOPOL resin present in the viscous hydrogen peroxide
solutions of the present invention is dependent upon the particular
CARBOPOL resin used and the desired viscosity. Solutions having a
Brookfield viscosity of 60 cps to 6,000 cps may be obtained by adding from
about 0.05 to about 0.5 weight percent of a CARBOPOL resin to the hydrogen
peroxide solution.
The solution viscosity is also related to pH. The pH may be adjusted from
4.5 to 8 without loss of active oxygen and the preferred range is 5 to 7.
When unmodified ultramarine blue is present in the viscous bleach, the pH
of the solution should be maintained in the range of 6.5 to 7.5.
Ultramarine blue is unstable below pH 6.5 and above ph 7.5 there is some
loss of available oxygen with time.
The viscous hydrogen peroxide solutions formed in accordance with the
present invention are exceptionally stable. They retain their viscosity
with very little loss over extended periods of time, an also are resistant
to loss of active oxygen on storage. They retain essentially all of their
active oxygen (e.g., 99.5%) even upon storage for as much as 6 months at
ambient temperature. This is quite contrary to what normally occurs when
surfactants other than those described herein are combined with CARBOPOL
resins.
The following examples are presented by way of illustration of our
invention only, and are not to be considered as limiting the scope thereof
in any way.
EXAMPLE I
A series of 24 commercially available thickening agents are evaluated by
adding 1% by weight of each thickening agent to a 6% hydrogen peroxide
solution (FMC Technical Grade). Except for carboxymethyl cellulose, all
agents thickened the solution. Viscosity was lost, however, within 2 days
except for the CARBOPOL solutions. CARBOPOL solutions neutralized with
triethanolamine lost viscosity after 4 days, whereas those neutralized
with sodium hydroxide retained viscosity for over 10 months. The data on
the 24 thickening agents evaluated in this Example I are summarized in
Table I.
EXAMPLE II
(a) A clear viscous hydrogen peroxide control solution is prepared by
adding 0.133 weight percent of CARBOPOL 940 to a 6% solution of hydrogen
peroxide (FMC Technical Grade) and adjusting the pH of the solution with
sodium hydroxide to 5.0. The hydrogen peroxide solution so obtained has a
viscosity of 4,420 cps, measured with the Brookfield Viscometer, Model
LVT, #3 spindle at 6 r.p.m. (viscosity 780 cps at 60 r.p.m.).
(b) Numerous nonionic surfactants are evaluated at concentrations of 1% by
weight in a viscous hydrogen peroxide - CARBOPOL system. The procedure
described in this Example, paragraph (a) above is repeated except that one
weight percent of a surfactant is added to the 6% hydrogen peroxide
solution (FMC Technical Grade) prior to addition of the CARBOPOL 940, and
pH adjustment. The pH of the
TABLE I
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THICKENING AGENTS TESTED
Viscosity Stability
Manufacturer
Trade Name
Chemical Classification
After One Month
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Alco Alcogum
L-11 Sodium polyacrylate
No
Alcogum
6625 Sodium polyacrylate
"
Dow Separan
CP 7 Cationic polyacrylamide
"
Separan
AP 30
Polyacrylamides
"
AP 273
MG L
MG 200
NP 10
GAF Gantrez
AN 4651
Poly (methyl vinyl ether/
maleic anhydride)
"
NP-K30 polyvinyl pyrrolidone
Goodrich, B. F.
Carbopol
934 Carboxy vinyl polymers
Yes
940 Yes
941 Yes
Hall, C. P.
Emulvis Polyethylene stearate
No
Hercules
CMC 7MT Carboxymethyl cellulose
"
Hodag Hodag C-100-T-AC
Cationic amine acetate
"
Hodag GMS Glycerol monostearate
"
Hodag PEG 6000
Polyethylene glycol
"
Sole-Terge AC50
K salt coc amino polyethoxy
sulfate "
Nopco Hyonic FA-40
Fatty alkylamide
"
Hyonic FA-70
Fatty alkylamide
"
Rohm & Haas
Acrysol GS
Sodium polyacrylate
No
Staley, A. E.
Elvanol T-25
Polyvinyl alcohol
"
Union Carbide
Carbowax 6000
Polymerized polyethylene
glycol "
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solution is adjusted to 5.0 with sodium hydroxide, and the initial
viscosity immediately after the neutralization step is measured with a
Brookfield Viscometer (at 6 r.p.m. and 60 r.p.m.) as described above in
paragraph (a). The surfactants tested in this manner are listed and
identified in Table II which summarizes the stability of the hydrogen
peroxide solution after 1 month.
EXAMPLE III
Various anionic surfactants were also evaluated. To a 6% solution of
hydrogen peroxide (FMC Technical Grade) is added 0.5 weight percent of a
sodium alkyl benzene sulfonate (sold under the trade name SULFRAMIN by
Witco, Organics Division, 277 Park Avenue. New York, N.Y. 10017). To this
solution is added with stirring 0.133 weight percent CARBOPOL 940. The
solution after addition of the CARBOPOL resin is adjusted to pH 5.0 with
aqueous sodium hydroxide. The viscous hydrogen peroxide solution so
obtained has a Brookfield viscosity of 160 cps (6 r.p.m.). After 5 months
storage at room temperature, this liquid bleach has a Brookfield viscosity
of 160 cps and had retained 100% of the available oxygen. Similar
formulations prepared by the method described in this Example containing
different quantities of CARBOPOL and SULFRAMIN are reported in Table III.
EXAMPLE IV
To a 6% solution of hydrogen peroxide (FMC Technical Grade) is added 1.0
weight percent of sodium lauryl sulfate, (sold under the trade name
DuPONOL ME DRY by E. I. DuPont de Nemours, Wilmington, Delaware). To this
solution is added with stirring 0.333 weight percent of CARBOPOL 940.
TABLE II
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Surfactant
Chemical Solution
Initial Was Viscosity Stable
Manufacturer
Trade Name
Classification
Appearance
Viscosity (cps).sup.1
For One Month
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None Clear 4420, 780
Yes
BASF Plurafac Oxyethylated
straight chain
alcohols
A-16 Cloudy 1740, 376
No
A-26 Clear 1380, 296
No
A-38 Clear 1480, 322
Yes
B-26 Clear 1340, 286
No
RA-20 Clear 2200, 426
No
RA-30 Clear 1560, 338
No
RA-40 Cloudy Incompatible,
phase separation
--
RA-43 Clear 2160, 444
No
RA-50 Clear 1420, 306
No
pluronics
Polyols.sup.2
F38.sup.(a) Clear 1760, 366
Yes
F68 Clear 1640, 350
Reduced
F77 Clear 1040, 238
Reduced
F87.sup.(b) Clear 2160, 448
Yes
F88 Clear 1360, 308
No
F98 Clear 1560, 350
No
F108 Clear 520, 142
No
F127.sup.(e) Clear 2100, 446
Yes
L31 Clear 1460, 316
No
L35 Clear 1900, 382
No
L42 Clear 1500, 320
No
L43 Clear 1840, 374
No
L44 Clear 1000, 236
No
L61 Cloudy 980, 228
No
L62 Clear 1640, 348
No
L63 Clear 2060, 386
No
L64 Clear 2440, 454
No
L72 Cloudy 920, 226
No
L92 Clear 1620, 354
No
L121 Cloudy 1740, 424
No
L122 Hazy 1400, 336
No
P65 Clear 1060, 242
No
P75 Clear 1780, 354
No
P84 Clear 1400, 298
No
P85 Clear 1980, 396
No
P94.sup.(c) Clear 860, 210
Yes
P103 Clear 1340, 288
No
P104 Clear 1060, 238
No
P105.sup.(d) Clear 1260, 274
Yes
25R2 Clear 1320, 292
No
BASF Plurodot HA-433
Trifunctional
Turbid Incompatible,
polyoxyalkylene phase separation
--
glycols
Emory Emid 6510
Lauric diethanol
Clear 120, 22 No
amide
GAF Igepal C0530
Nonyl phenoxy poly
Cloudy 1420, 330
No
(ethylene oxy)
ethanol
ICI Monflor 51
Fluorocarbons with
Clear 460, 126
No
highly branched
perfluoro groups
Monflor 52
Fluorocarbons with
Cloudy 340, 102
No
highly branched
perfluoro groups
Mona Monamide CMA
Coco monoethanol-
Turbid <10 --
amide
Monamide LMA
Lauryl monoethanol-
Turbid <10 --
amide
Minnesota
Fluorad FC-170
Fluorinated alkyl
Cloudy 2760, 550
No
Mining & polyoxyethylene
Manufacturing ethanols
Fluorad FC-430
Fluorinated alkyl
Clear 2280, 494
No
ester
Nopco Nopalcol 10-L
Polyoxymethylene
monolaurate
Rohm & Haas
Triton CF 10
Alkyl aryl poly-
Cloudy <10 --
ether
Triton X-100
Octyl phenoxy
Clear 580, 152
No
polyethoxy
ethanol
Shell Neodol 25-9
C.sub.12 --C.sub.15 linear
Clear 1000, 228
No
primary alcohol
ethoxylate
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.sup.1 The thickened solutions are "pseudoplastic", where flow is
increased by applying stress. The viscosities were measured using a
Brookfield viscometer with spindle speeds of 6 rpm (first number) and 60
rpm (second number). A viscosity of <10 cps is water consistency. Glyceri
has a viscosity of about 1000 cps.
.sup.2 Condensates of ethylene oxide with hydrophobic bases formed by
condensing propylene oxide with propylene glycol except for Pluronic 25R2
where ethylene oxide/ethylene glycol replaced propylene glycol.
.sup.(a) block copolymer polyols characterized by a hydrophilic lipophili
balance value of about 30.5 and a molecular weight of about 4,750; said
block copolymer polyol being obtained by adding poly(oxyethylene) groups
to a poly(oxypropylene) chain having a molecuular weight of about 950.
.sup.(b) characterized by hydrophilic lipophilic balance value of about 2
and a molecular weight of about 7,500; said block copolymer polyol being
obtained by adding poly(oxyethylene) groups to a poly(oxypropylene) chain
having a molecular weight of about 2,250.
.sup.(c) characterized by a hydrophilic lipophilic balance value of about
13.5 and a molecular weight of about 4,585; said block copolymer polyol
being obtained by adding poly(oxyethylene) groups to a poly(oxypropylene)
chain having a molecular weight of about 2,750.
.sup.(d) characterized by a hydrophilic lipophilic balance value of about
15 and a molecular weight of about 6,500; said block copolymer polyol
being obtained by adding poly(oxyethylene) groups to a poly(oxypropylene)
chain having a molecular weight of about 3,250.
.sup.(e) characterized by a hydrophilic lipophilic balance value of about
22 and a molecular weight of about 13,333; said block copolymer polyol
being obtained by adding poly(oxyethylene) groups to a poly(oxypropylene)
chain having a molecular weight of about 4,000.
TABLE III
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Surfactant Initial
Was Viscosity
Chemical CARBOPOL 940
Viscosity
Stable
Manufacturer
Trade Name
Class. Conc. (Wt. %)
Conc. (Wt.)
(cps) After One
__________________________________________________________________________
Month?
E. I. DuPont
DuPONOL ME
Alkali metal
de Nemours
DRY alkyl sul-
fate 0.5 0.133 160;
68 Yes
1.0 0.266 500;
136
Yes
Witco SULFRAMIN
Alkyl benzene
sulfonate
0.5 0.133 276;
89 Yes
0.166 1,000;
240
Yes
0.2 1,080;
296
Yes
0.266 1,160;
296
Yes
1.0 0.266 <100 Yes
0.333 180;
72 Yes
GAF Gafac RD 510
Acid organic
phosphate ester
0.5 0.133 160;
72 No
Hodag Sole Terge 8
Oleic acid iso-
(35% active)
propanol amide
sulfosuccinate
0.5 0.133 120;
34 No
Shell Neodol 25-3S
alcohol ethoxy
(58% active)
sulfate 0.5 0.133 160;
68 No
0.166 920;
226
No
0.2 1,340;
290
No
1.0 0.2 360;
106
No
0.233 1,180;
278
No
0.266 2,360;
536
No
1.7 0.266 160;
66 No
0.299 880;
186
No
0.333 1,280;
300
No
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The CARBOPOL is adjusted to (pH 5.0) with sodium hydroxide to give a stable
viscous hydrogen peroxide solution having a Brookfield viscosity of 500
cps (6 r.p.m.). The viscosity of this solution remained unchanged after 1
month storage at ambient temperature. A similar formulation prepared by
the method described in this Example containing different proportions of
CARBOPOL and DUPONOL ME DRY is reported in Table III which compares the
unique surfactants employed in the present invention with other anionic
surfactants.
EXAMPLE V
To a 6% aqueous solution of hydrogen peroxide (FMC Technical Grade) is
added 0.5 weight percent of an anionic surfactant. (DuPONOL ME DRY) and
0.5 weight percent of a nonionic surfactant (PLURONIC P 94). To this
mixture is added 0.133 weight percent CARBOPOL 940 and the solution is
adjusted to pH 5.0 with sodium hydroxide. The viscous liquid bleach so
obtained retains its viscosity for 1 month at ambient temperature and at
the end of 1 month retained 99.7% of the available oxygen originally
present.
EXAMPLE VI
To a 6 weight percent hydrogen peroxide solution (FMC Super D Grade) is
added 1% by weight PLURONIC P 94, 0.166 weight percent CARBOPOL 940, and
sufficient 10% aqueous sodium hydroxide to adjust the pH to 6.7. To the
viscous hydrogen peroxide solution so obtained is then added 0.17 weight
percent of ultramarine blue pigment. After 1 month storage at room
temperature, this solution is physically and chemically stable.
EXAMPLE VII
To a 6 weight percent hydrogen peroxide (FMC Super D Grade) solution is
added 1 weight percent DuPONOL ME DRY, 0.266 weight percent CARBOPOL 940
and sufficient 10% sodium hydroxide solution to adjust the pH to 6.7. To
this viscous liquid bleach is then added 0.17 weight percent ultramarine
blue pigment. After 1 month storage at room temperature, this solution is
physically and chemically stable. For optimum storage life an ultramarine
blue that is stabilized for use in an acid environment may be employed.
EXAMPLE VIII
A stable opaque liquid bleach is prepared by adding to a 6 weight percent
hydrogen peroxide solution (FMC Super D Grade) 1 weight percent PLURONIC P
94 and 0.166 weight percent CARBOPOL 940. The solution is adjusted to 5.0
with sodium hydroxide and 0.07 weight percent of a copolymer latex
opacifier (E 153 manufactured by Morton Chemical Company, Division of
Morton Norwich Products, Inc., 1275 Lake Avenue, Woodstock, Illinois
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