Note: Descriptions are shown in the official language in which they were submitted.
2 ~ 2 6 ~ ~ ~6230l-l87l
.
Field of Invention
This invention relates to a cleaner for hard surfaces, such
as bathtubs, sinks, ~iles, porcelain and enamelware, which
removes soap scum, lime scale and grease from such surfaces
without harming them. More particularly, the invention relates
to an acidic microemulsion that can be sprayed onto the surface
to be cleaned, and wiped off without usual rinsing and still
leave the cleaned surface bright and shiny. The invention also
relates to a method for using such compositions.
Back~round of Inventlon
Hard surface cleaners, such as bathroom cleaners and
scouring cleansers, have been known for many years. Scouring
cleansers normally include a soap or synthetic organic detergent
or surface active agent and an abrasive. Such products can
scratch relatively ~oft surfaces and can eventually cause them ~o
appear dull. These products are often ineffective to remove lime
scale ~usually encrusted calcium and magnesium carbonates) ln
normal use. Because lime scale can be removed by chemical ~`
reactions with acidic media various acidic cleaners have been -~
produced and have met with various degrees of success. In some
instances such cleaners have been failures because the acid
employed was too strong and damaged the surfaces being cleaned.
At other times, the acidic component of the cleaner reacted
objectionably with other components of the product which
adversely affected the detergent or perfume. Some cleaners
required rinsing afterward to avoid leaving objectionable
deposits on the cleaned surfaces. As a result of research
performed in efforts to overcome the mentioned disadvantages
212~52~ 62301-1871
.here nas recencl~ been made an improved liquld cieaning
composltion in s~able microemulsion form which is an effective
cleaner to remove soap scum, lime scale and greasy soils from
hard surfaces, such as bathroom surfaces and which does not
require rinsing after use. Such a product is described in U.S.
patent application S.N. 120,250 for Stable Microemulsion Cleaning
Composition filed November 12, 1987 by Loth, Blanvalet and
Valenge, which application is hereby incorporated by reference.
In particular, Example 3 of that application discloses an acidic,
clear, oil-in-water microemulsion which is therein described as
being successfully employed to clean shower wall tiles of lime
scale and soap scum that had adhered to them. Such cleaning was ;~
effected by applying the cleaner to the walls followed by wiping
or minimal rinsing after which the walls were allowed to dry to a
god shine.
The described microemulsion cleaner of the patent
application is effective in removing lime scale and soap scum
from hard surfaces and is easy to use, but it has been found that
its mixture of acidic agents (succinic, glutaric and adipic
acids) could damage the surfaces of some hard fixtures, such as
those of materials which are not acid resistant. One of such
materials is an enamel that has been extenslvely employed in
Europe as a coating for bathtubs, herein referred to as European
enamel. It has been described as zirconium white enamel or
zirconium white powder enamel and has the advantage of being
resistant to detergents, which makes it suitable for use on tubs,
sinks, shower tiles and bathroom enamelware. However, such
enamel is sensitive to acids and is severely damaged by use of
:: . .::: ~ :.: : `~ : ::: : .. :::-.. :. " .
2.~26g2~
- 62301-1871
~he mlcroemulsion acidic cleaner based on the chree organic
carboxylic acids previously mentioned.
That problem was been solved by EPO patent v336878A2. In
which additional acidic materials are lncorporated in the cleaner
with the organic acids and ra~her than exacerbat~ng the problem,
they prevent harm to such European enamel surfaces by such
organic acids. Also, a mixture of such additional acids,
phosphonic and phosphoric acids surprisingly further improves the
safety of the aqueous cleaner for use on such European enamel
surfaces and decreases the cost of the cleaner.
The instant compositions of present invention allow the
cleaning of European enamel surfaces, as well as any other acid
resistant surfaces of bathtubs and other bathroom surfaces. The
product can be used on various other materials that are
especially susceptible to attack by acidic media, such as marble. ~ -~
The instant compositions employ alpha-hydroxy aliphatic acids in
place of the mixture of succinic, glutaric and adipic acids
previously used in the acidic microemulsion. The instant
compositions which employ the alpha hydroxy aliphatic acids are
less detrimental to European enamel or other acid susceptible
surfaces such as marble than the mixture of succinic, glutaric
and adipic. Additionally, it is contemplated that the instant
inventions can be thickened by a xanthan gum such as described in
copending U.S. Serial No. 07/950,370 filed September 1992.
Summarv of the Invent~on
In accordance with the present invention, an acidic aqueous
cleaner for bathtubs and other hard surfaced items, which are
acid resistant or are of zirconium white enamel wnerein the
cleaner has a pH in the range of 1 to 4 and the c_eaner removes
2126626
62301-1871
lime scale, soap scum and greasy soil from surfaces of such items
without damaging such surfaces, comprises: a detersive proportion
of at least one synthetic organic detergent which is capable of
removing greasy soil from such surfaces; a lime scale and soap
scum removing proportion of an alpha hydroxy aliphatic acid; and
water.
Detailed Description of the Invention ;
The present thickened, acidic microemulsion compositions
preferably comprise approximately by weight: ~:
(a) 1 to 9 percent of an anionic surfactant such as an ~ :~
alkali metal or ammonium C10 20 paraffin sulfonate; an alkali
metal or ammonium C8-C18 alkyl sulfate or an alkaIi metal or
ammonium ethoxylated C8-C18 alkyl ether sulfate; :
(b) 0 to 6 percent, preferably 1 to 5 percent, of a
nonionic surfactant such as a C13 15 fatty alcohol EO 7:1/PO4:1;
(c) 0 to 0.7 percent of a preservative such as an .
alkali metal benzoate, for example, sodium benzoate;
(d) 0 to 1.0 percent of a xanthan gum thickener having
a molecular weight of about 1,000,000 to 10,000,000 such as
Kelzan T (trade-mark) sold by Merck & Co.; ::
(e) 0 to 0.3 percent of an alkali metal hydroxide;
(f) 0 to 1.0 percent of a phosphoric acid, more
preferably 0.05 to 1.0 percent; :~
(g) 0 to 0.5 percent of an aminoalkylenephosphonic
acid, more preferably 0.01 to 0.3 percent;
(h) 0 to 0.1 percent of a dye;
(i) 0 to 2.0 percent of a perfume;
. . . .. .. . ..
2 1 2 6 6 2 6 62301-1871
(~) 2 to 9 percent of at least one alpha hydroxy
aliphatic acid having 2 to about 6 carbon atoms; and
(k) balance being water, wherein the composition has
a pH of about 1 to about 4, more preferably about 2.7 to about
3.3 and a Brookfield viscosity of about 5 to 1,000 cps, more
preferably about 30 to about 600 cps at R.T. using a #2 spindle
and 50 rpms.
In the present compositions, the synthetic organic
detergent may be any suitable anionic, nonionic, amphoteric,
ampholytic, zwitterionic or cationic detergent or mixture thereof,
but the anionic and nonionic detergents are preferred as well as
mixtures thereof. `~
The nonionic surfactant that can be employed in present
liquid detergent composition is present in amounts of about 0 to
5%, preferably 0.5 to 4.5~i, most preferably l to 4%, by weight of ;~
the composition and provides superior performance in the removal :
of soil.
The water soluble nonionic surfactants utilized in this ::
invention are commercially well known and include the primary
aliphatic alcohol ethoxylates, secondary aliphatic alcohol
ethoxylates, alkylphenol ethoxylates and ethylene-oxide-propylene
oxide condensates on primary alkanols, such as Plurafacs (BASF)
and condensates of ethylene oxide with sorbitan fatty acid esters
such as the Tweens (ICI). The nonionic synthetic organic
detergents generally are the condensation products of an organic .
aliphatic or alkyl aromatic hydrophobic compound and hydrophilic
2126626 62301-1871
e~hylene oxlde groups. Practicaily any h~arophobic compound
having a carboxy, hydroxy, amido, or amino group with a free
hydrogen attached to the nitrogen can be condensed with ethylene
oxide or with the polyhydration product thereof, polyethylene
glycol, to form a water soluble nonionic detergent. Further, the
length of the polyethenoxy hydrophobic and hydrophilic elements.
The nonionic detergent class includes the condensation
products of a higher alcohol ~e.g., an alkanol containing about 8
to 18 carbon atoms in a straight or branched chain configuration)
condensed with about 5 to 30 moles of ethylene oxide, for
example, lauryl or myristyl alcohol condensed with about 16 moles
of ethylene oxide (EO), tridecanol condensed with about 6 to
moles of EO, myristyl alcohol condensed with about 10 moles of EO ;~
per mole of myristyl alcohol, the condensation product of EO with
a cut of coconut fatty alcohol containing a mixture of fatty
alcohols with alkyl chains varying from 10 to about 14 carbon
atoms in length and wherein the condensate contains either about
6 moles of EO per mole of total alcohol or about 9 moles of EO
per mole of alcohol and tallow alcohol ethoxylates containing 6
EO to 11 EO per mole of alcohol.
A preferred group of the foregoing nonionic surfactants are
the Neodol ethoxylates (Shell Co.), which are higher aliphatic,
primary alcohol containing about 9-15 carbon atoms, such as
Cg-Cll alkanol condensed with 8 moles of ethylene oxide (Neodol
91-8), C12_13 alkanol condensed with 6.5 moles ethylene oxide
(Neodol 23-6.5), C12-1s alkanol condensed with 12 moles ethylene
oxide (Neodol 25-12), C14-1s alkanol condensed with 13 moles
ethylene oxide (Neodol 45-13), and the like. Such ethoxamers
have an HLB (hydrophobic lipophilic balance) ~alue of about 8 to
.:
21266~ 62301-1871
~_ and glve good o/w emuis1rication, ~hereas ethoxamers with HLB
-~alues below 8 contaln less than 5 ethyleneoxide groups and tend
i-o be poor emulsifiers and poor detergents.
~ dditional satisfactory water soluble alcohol eth~ilene oxide
condensates are the condensation products of a secondary
aliphatic alcohol containing 8 to 18 carbon atoms in a straight
or branched chain configuration condensed with 5 to 30 moles of
ethylene oxide. Examples of commercially available nonionic
detergents of the foregoing type are C11-C1s secondary alkanol
condensed with either 9 EO ~Tergitol 15-S-9) or 12 EO (Tergitol
15-S-12) marketed by Union Carbide.
Other suitable nonlonic detergents include the polyethylene
oxide condensates of one mole of alkyl phenol containing from
about 8 to 18 carbon atoms in a straight- or branched chain alkyl
group with about 5 to 30 moles of ethylene oxide. Specific
examples of alkyl phenol ethoxylates include nonyl condensed with
about 9.5 moles of EO per mole of nonyl phenol, dinonyl phenol
condensed with about 12 moles of EO per mole of phenol, dinonyl
phenol condensed with about 15 moles of EO per mole of phenol and
di-isoctylphenol condensed with about 15 moles of EO per mole of
phenol. Commercially available nonionic surfactants of this type
include Igepal C0-630 (nonyl phenol ethoxylate) marketed by GAF
Corporation.
Also among the .satisfactory nonionic detergents are the
water-soluble condensation products of a C8-C20 alkanoi with a
heteric mixture of ethylene oxide and propylene oxide wherein the
weight ratio of echylene oxide to propylene oxide is f~om 2.5:1
to 4:1, preferably 2.8:1 to 3.3:1, with the total of the ethylene
oxide and propylene oxide (including the terminal ethanol or
~126~26 62301-1871
~~-panol group) _~1na .-om 60 to 85~, prererabiy 0 to 80%, 'oy
~elght. Such detergen~s are commercially available from BASF-
'~yandotte and a ~articularly preferred detergent is a C1o-C16
alkanol condensate with ethylene oxide and propylene oxide, the
we1gnt ratio of eshylene oxide to propylene oxide being 3:1 and
the total alkoxy content being about 75% by weight.
Condensates of 2 to 30 moles of ethylene oxide with sorbitan
mono- and tri-Clo-C20 alkanoic acid esters having a HLB of 8 to
15 also may be employed as the nonionlc detergent ingredient in
the described shampoo. These surfactants are well known and are
available from Imperial Chemical Industries under the Tween trade
name. Suitable surfactants include polyoxyethylene (4) sorbitan
monolaurate, polyoxyethylene (4) sorbitan monostearate,
polyoxyethylene (20) sorbitan trioleate and polyoxyethylene (20)
sorbitan tristearate.
Other suitable water-soluble nonionic detergents which,are
less preferred are marketed under the trade name "Pluronics~
The compounds are formed by condensing ethylene oxide with a
hydrophobic base formed by the condensation of propylene oxide
with propylene glycol. The molecular weight of the hydrophobic
portion of the molecule is of the order of 950 to 4000 and
preferably 200 to 2,500. The addition of polyoxyethylene
radicals to the hydrophobic portion tends to increase the
solubility of the molecule as a whole so as to make the
surfactant water-soluble. The molecular weight of the block
polymers varies from 1,000 to 15,000 and the polyethylene oxide
content may comprise 20% to 80% by weight. Preferably, these
sur~actants will be in liquid form and satisfactory surfactants
are available as grades L62 and L64.
2 ~ ~ 6 6 2 6 6230l-l87l
~ .e anlonl_ sur~actant, used ln -ne microemuislon
composition, constitutes about 1% to ,~%, preferably 2~ to 8~,
most preferably 2% to 7%, by weight.
The anionic surfactant which may be used in the instant
microemulsion de~ergent of the inventlon are water soluble such
as triethanolamine salt and include the sodium, potassium,
ammonium and ethanalommonium salts of Cg_1g alkyl sulfates such
as lauryl sulfate, myristyl sulfate and the like; Cg-C1g
ethoxylated alkyl ether sulfates; linear Cg-C16 alkyl benzene
sulfonates; C10-c2o paraffin sulfonates; alpha olefin sulfonates
containing about 10-24 carbon atoms; Cg-C1g alkyl sulfoacetates;
C8-C1g alkyl sulfosuccinate esters; Cg-C1g acyl isethionates; and
Cg-C1g acyl taurates. Preferred anionic surfactants are the water
soluble alkyl sulfates.
The paraffin sulfonates may be monosulfonates or di-
sulfonates and usually are mixtures thereof, obtained by
sulfonating paraffins of 10 to 20 carbon atoms. Preferred
paraffin sulfonates are those of C12-1g carbon atoms chains, and
more preferably they are of C14-17 chains. Paraffin sulfonates
that have the sulfonate group(s) distributed along the paraffin
chain are described in U.S. Patents 2,503,280; 2,507,088;
3,260,744; and 3,372,188; and also in German Patent 735,096.
Such compounds may be made to specifications and desirably the
content of paraffin sulfonates outside the C14-17 range will be
minor and will be minimized, as will be any contents of di- or
poly-sulfonates.
Examples of suitable other sulfonated anionic detergents are
the well known higher alkyl mononuclea~ aromatic sulfonates, such
as the higher alkylbenzene sulfonates con~aining 9 to 18 or
~i'
-~~` 2 ~ 2 ~ 1871
oreferabl, ~ or :~ to ~5 or lo carbon atoms ln the hlgher alkyl
group ln a stralght or branched chain, or Cg-1s alkyl toulene
sulfonates. ~ ~rererred alkylbenzene sulfonate is a linear
alkylbenzene sul-onate having a higher content of 3-phenyl (or
higher) isomers and a correspondingly lower content (well below
50%) of 2-phenyl (or lower) isomers, such as those sulfonates
wherein the benzene ring is attached mostly at the 3 or higher
(for example 4, 5, 6 or 7) position of the alkyl group and the
content of the isomers in which the benzene ring is attached in
the 2 or 1 position is correspondingly low. Preferred materials
are set forth in U.S. Patent 3,320,174, especially those in which
the alkyls are of 10 to 13 carbon atoms.
The higher alkyl ether sulfates used in the present
invention are represented by the formula:
RO(C2H4O)nSO3M
in which R is a primary or secondary alkyl group that may be
straight or branched having from 10 to 18 carbon atoms,
preferably 12 to 15, especially 12 to 14, and most preferably 12
to 13 carbon atoms. M is an alkali metal or ammonium cation and
n is a number from 1 to 10, preferably 1 to 6, especially 2 or 3.
These de~ergents are produced by sulfating the corresponding
ether alcohol and then neutralizing the resulting sulfuric acid
ester thereof. The sodium and ammonium salts of the ether
sulfates are especially preferred.
The alkyl sulfate anionic detergent compounds which are
useful in the present invention have from 6 to 18 in the alkyl
group and can be represented by the following general formula:
R2SO4M
212662~ 6230l-l87l
n wnlc;~ P.~ s s~rl~igAt c~ ~ranched chaln alkyi _~ -rom 6 to 8,
especially ~om 8 to 14 carbon atom chain leng~h and M is an
alkali metai or ammonium carbon, especially sodium. Straight
chain alkyl groups are preferred.
The active acidic component of the acidic emulsions is an
alpha hydroxy aliphatic acid which is strong enougn to lower the
pH of the microemulsion to one in the range of one to four.
Various such carboxylic acids can perform this function but those
which have been found effectively to remove soap scum and lime
scale from bathroom surfaces best, while still not destabilizing
the emulsion, are alpha hydroxy aliphatic acids having the
structure:
X , . '
Y 1- OH
C02H
wherein Y is selected from the group consisting of hydroxy or a
COOH group and X is (CH2)nW, wherein W is selected from the group
consisting of CH3 or COOH and n is 0, 1, or 2. Preferred alpha
hydroxy aliphatic acids are citric acid, lactic acid and malic
acid, wherein a mixture of lactic acid and malic acid is
preferred, wherein the weight ratio of lactic acid to malic acid
is preferred to be about 5:1 to about 1:1, more preferably about
4:1 to about 1:1. The at least one alpha hydroxy aliphatic acid
is incorporated in the composition in an amount of about 2 to
about 9 wt. %, more preferably about 2 to about / wt. %.
The alpha hydroxy aliphatic acid, after being incorporated
in the acidic emulsion, may be partially neutra,ized to produce
the desired pH in the emulsion, for greatest functional
effectiveness, with safety.
11
,: -.. : . .~ . :. , -~ . . . ...
2~26~2~ 6230l-l87l
Phosphoric acid is one of the additional acids that
helps to protect acid-sensitive surfaces being cleaned with the
present emulsion cleaner. Being a tribasic acid, it too may be
partially neutralized to obtain an emulsion pH in the desired
range. For example, it may be partially neutralized to the
biphosphate, e.g., NaH2PO4 or ~H4H2PO4.
Phosphonic acid, the other of the two additional acids
for protecting acid-sensitive surfaces from the dissolving action
of the dicarboxylic acids of the present thickened emulsions,
apparently exists only theoretically, but its derivatives are
stable and are useful in the practice of the present invention.
Such are considered to be phosphonic acids as that term is used
in this specification. The phosphonic acids are of the structure:
OH
y p O ~ ;
OH
wherein Y is any suitable substituent, but preferably Y is alkyl-
amino or N-substi*uted alkylamino. For example, a preferred
phosphonic acid component of the present thickened acidic
emulsions is aminotri(methylenephosphonic) acid which is of the
formula N(CH2PH2O3)3. Among other useful phosphonic acids are
ethylenediaminetetra(methylenephosphonic) acid, hexamethylene-
diaminetetra(methylenephosphonic~ acid, and diethylenetriamine-
penta(methylenephosphonic) acid. Such class of compounds may be
described as aminoalkylenephosphonic acids containing in the
ranges of 1 to 3 amino nitrogen, 3 or 4 lower alkylenephosphonic
acid groups in which the lower alkylene is of l or 2 carbon atoms,
and 0 to 2 alkylene groups of 2 to 6 carbon
12
.. .:
- 212662~ 62301-1871
atoms -acn, :;n~ aikyiene~s~ is/are ~resent and join amino
nitrogen wnen a riuralit-; ~f such amlno nitrogen is present in
the aminoalkyienepnosphon_c acld. It has been found that such
aminoalkylenepAosphonic acids, which also may be partially
neutraiized a~ the deslred pH of the microemulsion cleaner, are
of desired stabili7ing and protecting effect in the invented
cleaner, especially when present with phosphate acid, preventing
harmful attacks on European enamel surfaces by the alpha hydroxy
aliphatic components of the cleaner.
The thickener which is optionally used in the acidic
microemulsion is a xanthan gum called Kelzan T and sold by Merck
& Co. The xanthan gum is an exocellular hetropolysaccharide
having a molecular weight of about 1,000,000 to 10,000,000 and is
used in a concentration of o to about 1.0 weight percent, more
preferably about 0.1 to about 0.7 weight percent, and most
preferably 0.2 to 0.6 weight percent. When used at these
concentration levels, the composition retains its microemulsion
characteristics in that the essential micellar aggregates are
maintained. The composition is still sprayable and will nicely
cling to a vertical wall. Additionally, the compositions having
the xanthan gum incorporates therein are shear thinning which
means that the composition can be easily removed from the surface
being cleaned without much mechanical action. Other cellulose,
hydroxypropyl cellulose, ?olyacrylamides and poly vinyl alcohol
will create shear thickening compositions.
The water ~hat is used in making the present microemulsions
may be tap water but is preferably of low hardness, normally
being less than 150 parts per million (p.p.m.) of hardness.
Stil', useful cleaners can be made from tap waters that are
13
- 2 1 2 6 6 ~ ~ 62301-1871
:~larer in haraness, u~ ~o 000 p.p.m.. Mos~ creferably the ~ater
emp_~ved will be disti~led or deionized water, n which the
conten~ of hardness ions is less than ~5 p.p.m.
~ arlous other components may desirably be present in the
inven~ed cleaners, including preservatives such as sodium
benzoate, antioxidants or corrosion inhibitors, cosolvents,
cosurfactant, multivalent metal ions, perfumes, colorants and
terpenes (and terpineois), but various other adjuvants
conventionally employed in liquid detergents and hard surface
cleaners may also be present, provided that they do not interfere
with the cleaning and scum-and scale-removal functions of the
cleaner. Of the various adjuvants (which are so identified
because they are not necessary for the production of an operative
cleaner, although they may be very desirable components of the
cleaner) the most important are considered to be the perfumes,
which, with tarpenes, terpenes and hydrocarbons (which may be
substituted for the perfumes or added to them) function as
especially effective solvents for greasy soils on hard surfaces
being leaned, and form the dispersed phases of oil-in-water (o/w)
microemulsions. Also of functional importance are the co-
surfactant and polyvalent metal ions, with the former helping to
stabilize the microemulsion and the latter adding in improving
detergency, especially for more dilute cleaners, and when the
polyvalent salts of the anionic detergent employed are more
effective detergents against the greasy soil encountered in use.
The various perfumes that have been found to be useful in
forming the dispersed phase of the thickened acidic microemulsion
cleaners may be those normally employed in cleaning products and
preferably are normally in liquid state. They include esters,
14
2 1 2 6 ~ 2 6 6230l-l87l
~ners, aldehydes, alcohols and alkanes employed in perrumery but
cf most impor~ance are the essential oils that are high in
~erpene contenc. It appears that the ~erpenes (and terpineols)
coact with the detersive components of microemulsions to improve
decergency of the invented compositions, in addition to forming
the stable dispersed phase of the microemulsions. In the present
invention it has been found that especially when a piney perfume
is being employed, one can decrease the proportion of
comparatively expensive such perfume and can compensate for it
with alpha-terpineol, and in some instances with other terpenes.
For example, for every 1% of perfume one can substitute from 60
to 90% of it, w.g., about 80~, with alpha-terpineol, and obtain
essentially the same piney scent, with good cleaning and ~-
microemulsion stability. Similarly, terpenes and other terpene-
like compounds and derivatives may be employed, but alpha-
terpineol is considered to be the best.
The polyvalent metal ion present in the invented cleaners
may be any suitable ion including, but not limited to, magnesium
(usually preferred) aluminum, copper, nickel, iron or calcium.
The ion or mixture thereof may be added in any suitable form,
sometimes as an oxide or hydroxide, but usually as a water
soluble salt. It appears that the polyvalent metal ion reacts
with the anion of the anionic detergent (or replaces the
detergent cation, or makes an equivalent solution in the
emulsion), which improves detergency and generally improves other -~
properties of the product, too. If the polyvalent metal ion
reacts with the detergent anion to form an insoluble product such
polyvalent ion should be avoided. For example, calcium reacts
with paraffin sulfonate anion to form an insoluble salt, so
2l2662~23ol-l87l
_alc~um 1ons, sucn ~s mlght ve obtained from calc~um chloride,
.^Jill be omitted ~rsm any mlcroemulsion cleaners of this invention
that contain parar_in sulfonate detergent. Similarly, those
polyvalent ions or other components of the invented compositions
that will react adversely with other components will also be
omitted. AS was mentioned previously, the polyvalent metal ion
will preferably be magnesium, and such will be added to the other
emulsion components as a water soluble salt. A preferred such
salt is magnesium sulfate, usually employed as its heptahydrate
(Epson salts), but other hydrates there or the anhydride may be
used too. Generally, the sulfates of the polyvalent metals with
the used because the sulfate anion thereof is also the anion of
some of the anionic detergents and is found in some such
detergents as a byproduct of neutralization.
The cosurfactant component~s) of the acidic cleaners reduce
the interfacial tension or surface tension between the lipophilic
droplets and the continuous aqueous medium to a value that is
often close to 10-3 dynes/cm., which results in spontaneous
disintegrations of the dispersed phase globules until they become
so small as to be invisible to the human eye forming a clear
microemulsion. In such a microemulsion the surface area of the
dispersed phase increases greatly and its solvent power and
grease removing capability are also increased, so that the acidic
microemulsion is significantly more effective as a cleaner for
removing greasy soiled than when the dispersed phase globules are
of ordinary emulsion size. Among the cosurfactants that are
useful in the inven~ed cleaners are: water soluble lower alkanols
of 2 to 4 carbon a~oms per molecule (sometimes preferably 3 or
4): polypropylene glycols of 2 to 18 propoxy units; monoalkyl
2~26626 6230l-l87l
_ower ~ ycol e~ners c- -he formuia RO (~ n, ~merein ? is C1_~
~lkyi, :~ is C~ C~CH o or CH(CH~CH~O, and n is from l to 4;
monoalkyl esters Gr the formula ~l if C~_4 acyl and X and n are
as immeàiately previously described; aryl substitu~ed alkanols of
i to ~ carbon atoms; propylene carbonate; alpha hydroxy aliphatic
acids of ~ to 6 carbon atoms such as mono- di- and tri hydroxy
substituted aliphatic mono- di- and tricarboxylic acids of 2 to 6
carbon atoms; lower alkyl mono- di- and triesters of phosphoric
acid wherein the lower alkyl is of l to 4 carbon atoms; and
mixtures thereof.
It also obvious that other previously identified
cosurfactants can be used in combination with the alpha hydroxy
aliphatic acids which function as cosurfactants. These non acid
cosurfactants will usually be used in conjunction with the alpha
hydroxy aliphatic acid cosurfactants in an amount of about O.l to
about 5 wt. %, more preferably about 0.5 to about 4.0 wt. %
depending upon the concentration of the alpha hydroxy aliphatic
acid cosurfactant.
Representative of such cosurfactants are lactic, malic and
citric acids, diethylene glycol monobutyl ether, dipropylene
glycol monobutyl ether and diethylene glycol mono-isobutyl ether,
which are considered to be the most effective.
From the foregoing discussion of useful cosurfactants in the
present cleaners it is apparent that malic, lactic and citric
acids, and a mixture of such components are useful for lowering
the pH of the product so that it removes soap scum and lime scale
easily from surfaces to be cleaned, and at the same time they
function as cosurfactants, improving the appearance of the
product and making it more effec~ive for removing grease from
17
2 ~ 2 6 ~ 2 ~ 62301-1871
such s~--aces. ~lmllar auai -rreces may be obtalned ky use of
other c_ the named acidic materials that have cosurfactant
acti~;tles ln the described cieaners.
Tn the invented cleaners :t is important that the
proportlons of the components are in certain ranges so that the
product may be mos~ effective n removing greasy soils, lime
scale and soap scum, and other deposits from the hard surfaces
subjected to treatment, and so as to protect such surfaces during
such treatment. As was previously referred to the detergent
should be present in detersive proportion, sufficient to remove
greasy and oily soils; the proportion~s) of the alpha hydroxy
aliphatic acid(s) should be sufficient to remove soap scum and
lime scale; the phosphonic acid or phosphoric and phosphonic
acids mixture should be enough to prevent damage of acid
sensitive surfaces by the alpha hydroxy aliphatic acid(s); and
.:
the aqueous medium should be a solvent and suspending medium for
the required components and for any adjuvants that may be
present, too. Normally, such percentages of components will be
by weight 0 to 1.0% of xanthan gum, 1 to 9% of synthetic anionic
organic detergent~s), 0 to 5% of synthetic organic nonionic
detergent(s), 2 to 9% of alpha hydroxy aliphatic acids, 0.05 to
.6% of phosphoric acid or mono-salt thereof and 0.005 to 2% of
phosphonic acid(s), 0 to 0.6% aminoalkylenephosphonic acid(s), or
mono-phosphonic salt(s) thereoî; and the balance being water and
adiuvant(s) if any are present. Of the alpha hydroxy aliphatic
acids it is preferred that a mixture of lactic and malic acids be
employed.
The ratio of the alpha hydroxy aliphatic acid to the
aminoaikylenephosphonic acid in the instan~ composition is about
18
2126~6 62301-1871
~:1 to abou~ ~50:i, more prererably about 2:1 ~o about 10:1 ana
~he ratio o~ the alpha hydroxy aliphatic acid to the phosphoric
acid is about 5:2 to 25:1.
Usually there will be present in the cleaner, especially
when an anionic surfactant is present 0.05 to 5~, and preferably
0.1 to 3.0% of polyvalent ion, preferably magnesium or aluminum,
and more preferably magnesium. Also, the percentage of perfume
will normally be in the 0.2 to 2% range, preferably being in the
O.S to 1.5% range of which perfume at least 0.1% is terpene or
terpineol. The terpineol is alpha-terpineol and is preferably
added to allow a reduction in the amount of perfume, with the
total perfume ~including the alpha-terpineol) being S0 to 90% of
terpineol, preferably about 80~ thereof.
The p~ of the various preferred microemulsion cleaners is
usually 1 to 4, preferably l.S to 3.5 e.t. 3. The water content
of the microemulsions will usually be in the range of about 75 to
90%, preferably about 80 to 85~ and the adjuvant content will be
from 0 to 5%, usually about 1 to 3%. If the pH is not in the
desired range it will usually be adjusted with either sodium
hydroxide or suitable acid, e.g. sulfuric acid, solution, but
normally the pH will be raised, not lowered, and it if is to be
lowered more of the alpha hydroxy acid mixture can be used,
instead.
The liquid cleaners can be manufactured by mere mixing of
the various components thereof, with orders or additions not
being critical. However, ic is desirable for the optionally
added xanthan gun to be first mixed with the water, various water
soluble components to be mixed together into the xanthan gum
solution, the oil soluble components to be mixed together in a
19
` 2126626 62301-1871
separate opera~lon, and the tWO mlXeS tO be a~mixed, wich the oii
soluble portion being added to the water soluble portion (in the
waterJ wlth stirring or other agitation.
In some instances, such procedure may be varied to prevent
any undesirable reactions between components. For example, one
would not add concentrated phosphoric acid directly to magnesium
sulfate or to a dye, but such additions would be of aqueous
solutions, preferably dilute of the components.
The cleaner may desirably be packed in manually operated
spray dispensing containers, which are usually and preferably
made of synthetic organic polymeric plastic material, such as
polyethylene, polypropylene or polyvinyl chloride (PVC). Such
containers also preferably include nylon or other non-reactive
plastic closure, spray nozzle, dip tube and associated dispenser
parts, and the resulting packaged cleaner is ideally suited for
use in Uspray and wipe" applications. ~owever, in some
instances, as when lime scale and soap scum deposits are heavy,
the cleaner may be left on until it has dissolved or loosened the
deposit(s) and may then be wiped off, or may be rinsed off, or
multiple applications may be made, followed by multiple removals,
until the deposits are gone.
The following examples illustrates but do not limit the
invention. All parts, proportions and percentages in the
examples, the specification and claims are by weight and all
temperatures are in C unless otherwise indicated.
2126~2~ 62301-~871
ExamDle .1
ComDonent % (bv weiah~)
C
Sodium lauryl sulfate 4.00 3.0 4.0
C13_1s Na Benzoate 0.30 0.3 0 3
Magnesium sulfate
heptahydrate 1.50 1.5 1.5
Malic acid 2.0 2.0 __
Lactic acid 2.0 3.0 --
Citric acid -- ~~ 4.0
Aminotri 0.25 0.25 0.25
Methylphosphonic Acid
Phosphoric Acid 0.~25 0.~25 0.425
Perfume ~contains 0.8 0.8 0.8
about 40% terpenes)
Dye 0.002 0.002 0.002
Water Balance Balance Balance
pH 3.0 3.0 3.0
Viscosity Brookfield 10 10 10
RT, ~2 spindle
Sorpins (cps) Balance
100 . 00
The microemulsion cleaner is made by dissolving the optional
xanthan gum and benzoates and then dissolving the detergent in
the water, after which the rest of the water soluble materials
are added to the detergent solution, with stirring, except for
the perfume and the adjusting agent (sodium hydroxide solution).
The pH is adjusted to 3.0 and then the perfume is stirred into
the aqueous solution, instantaneously generating the desired
microemulsion, which is clear blue.
The acid cleaner is packed in polyethylene squeeze bottle
equipped with polypropylene spray nozzles which are adjustable to
closed spray and stream positions. In use the microemulsion is
sprayed onto ~bathtub ring~ on a bathtub, which also includes
lime scale, in addition tO soap scum and greasy soil. The rate
of application is about 5 ml. per 5 meters of ring (which is
about 3 cm. wide). After application and a wait of about two
21
2 1 2 6 6 2 6 62301-1871
mlnuces the rlng is wiped off with a sponge and ls spongea off
with water, it is found that the greasy soii, soap scum, and even
the iime scale, have been removed effectiveiy. In those cases
where the lime scale is particularly thlck or adherent a second
application may be desirable, but that is t3 considered to be the
norm.
The tub surface may be rinsed because it is so easy tO rinse
a bathtub (or a shower) but such rinsing is not necessary.
Sometimes dry wiping will be sufficient but if it is desired
to remove any acidic residue the surface may be sponged with ~ -
water or wiped with a wet cloth but in such case it is not
necessary to use more than ten times the weight of cleaner
applied. In other words, the surface does not need to be
thoroughly doused or rinsed with water, and it still will be
clean and shiny (providing that it was originally shiny). In
other uses of the cleaner, it may be employed to clean shower
tiles, bathroom floor tiles, kitchen tiles, sinks and enamelware,
generally, without harming the surfaces thereof. It is recognized
that many of such surfaces are acid-resistant but a commercial
product must be capable of being used without harm on even less
resistant surfaces, such as European enamel (often on a cast iron
or sheet steel base) which is sometimes referred to as zirconium
white powder enamel. It is a feature of the cleaner described
above (and other cleaners of this invention) that they clean hard
surfaces effectively but they do contain ionizable acids and
therefore should not be applied to acid-sensitive surfaces.
Nevertheless, it has been found that they do not harm European
white enamel bathtubs, in this example, which are seriously
affected by cleaning with preparations exactly like that of this
22 ;~
2126~26
62301-1871
example except .or the omisslon from them or the phosphonlc acid
or the phosphoric-phosphoric acid mixture.
