Note: Descriptions are shown in the official language in which they were submitted.
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ACIDIC AQUEOUS LIQUID COMPOSITIONS
Technical field
The present invention relates to acidic aqueous liquid compositions,
2 0 more particularly to acidic aqueous compositions comprising sulphuric
acid and a specific chelating agent, or mixtures thereof. Said
compositions find particular application in the cleaning of hard-surfaces,
especially inclined hard-surfaces, such as toilet bowls and the like.
Backqround
On hard surfaces there is often deposition of mineral encrustations. This
3 0 type of soil is composed of calcium carbonate and, in case of toilet
bowls, of other calcium salts. The deposition of mineral encrustations is
related to water evaporation and to the action of microorganisms ~e.g.,
bacteria) present on toilet bowl surfaces. Mineral encrustations are
aesthetically unpleasant and, especially in toilet bowls, favor the
3 5 subsequent deposition of additional soils. It is therefore important to
inhibit/reduce this soil deposition phenomenon.
A great variety of acidic compositions have been described in the art.
Acidic compositions comprising a strong source of acidity, such as
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sulphuric acid, are particularly interesting for the cleaning of hard-
surfaces, especially for the hygienic cleaning of sanitary fittings such as
toilet bowls and the like.
5 However, such compositions containing sulfuric acid have not been
found to be satisfactory from a consumer view-point regarding the
surface appearance, i.e. shine and/or cleaning perlFormance, delivered to
the surface being treated therewith. Indeed, an acidic composition
containing sulphuric acid, when used to remove mineral encrustations
10 from a hard-surface, may leave residues on it, which appear as streaks
when water has evaporated. This is particularly evident when the
encrustations are enriched of calcium salts, for instance, in presence of
hard water and when the composition is used neat. In other words, it
has been found that the presence of sulfate anions coming from
15 sulphuric acid and of calcium cations coming from mineral encrustations
and/or from the hardness of the tap water used, react together so as to
form calcium sulfate residues (as depicted in the following reactions)
which are detrimental to the final surface appearance.
2H + + S042- + ~ H2O + CaSO4 + C~2(~aS)
CaCO 3(encrustation)
2H + + S042- + Ca2 + (from tap =~ 2H + + CaS04
water)
2 0 In fact, calcium sulfate residues may make the consumer believe that
the acidic composition is not effective in rernoving the toilet soils
because the calcium sulfate residues can be perceived by the consumer
as soils not having been removed. In addition or alternatively,
consumer may think that product performance in terms of shine is not
2 5 satisfactory because of calcium sulfate residues. Also, calcium sulfate
residues may slightly decrease the mineral encrustation removal
effectiveness of the acidic composition. In fact, calcium sulfate residues
cover the mineral encrustations thus lowering the collision probability
between H + ions and mineral encrustations themselves. This reduces
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the proba~liity that said encrustations could react with H + ions and
consequently be removed.
it is thus an object of the present invention to formulate acidic aqueous
5 compositions comprising sulphuric acid, which enable to remove mineral
encrustations from hard surfaces without leaving residues thus
delivering improved surface appearance.
It is also desirable to formulate compositions which comprise bleaches.
10 Indeed, bleaches possess many desirable properties, including
disinfection properties. Furthermore, such compounds, as
monopersulfuric acid, are particularly effective as disinfectants and in
removing and or decolouring stains for household cleaning applications.
However, when formulating acidic aqueous compositions which further
15 comprise bleaches stability problems appear, i.e. in general bleaches
raise compatibility issues in relation with the acids used to remove
mineral encrustations. It is thus an object of the present invention to
provide an acidic aqueous composition which can be formulated with
bleaches, in particularly persulfuric acid, in a stable manner.
It has now been found that the above mentioned objects could be met
by formulating an acidic aqueous composi~ion comprising sulphuric acid
and a chelating agent having a pKa not higher than 4, preferably not
higher than 2. More particularly, it has unexpectedly been found that
25 the addition of such a chelating agent to an acidic aqueous composition
comprising sulphuric acid allows to inhibit the formation and subsequent
precipitation of calcium sulfate, when the above composition is applied
on inorganic soils like calcium carbonate or calcium phosphate
encrustations commonly found in hard-surfaces, like toilet bowls,
30 resulting thereby in improved surface appearance.
An advantage of the present invention is that the end result advantage
in terms of surface appearance is particularly noticeable when the
composition is used neat, for example, when used for cleaning toilet
35 bowls above the toilet water line, when the water hardness is high and
in presence of calcium salts enriched soils.
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Another advantage of the present invention is that said aqueous acidic
compositions are efficient on v~3rious surfaces to clean various soils and
stains.
5 Additionally, the preferred compositions of the present invention which
further comprise a source of active oxygen, such as monopersulfuric
acid, when used to treat hard surfaces, especially toilet bowls, exhibit
outstanding soil discoloration together with a germicidal action, this
when used both neat or diluted. A further advantage of the
i 0 compositions of the present invention is that said compositions are
chemically stable for long storage periods. lndeedr the chelating agents
having a pka not higher than 4 contribute to the stability of the acidic
aqueous compositions of the present invention which further comprise a
source of active oxygen.
Also, the preferred compositions of the present invention which further
comprise a thickening surfactant system cc~mprising quaternary
ammonium compound and short chain amine oxide (C6-C10), exhibit
improved thickening properties at low total thickening surfactant level.
The following patent applications are representative of the prior art.
EP-A-421 974 discloses aqueous compositions of peracetic acid which
further comprise a sequestrant such as hydroxyaminocarboxylic acids,
5 alkyl polyphosphonic acid/ alkyl phosphonic ac,id derivatives. No
sulfuric acid is disclosed in EP-A-421 974.
EP-A-411 708 discloses acidic hard surface cleaners having a pH of
from 1 to 4 and comprising amongst other ingredients, a synthetic
30 organic detergent, an organic acid, an aminoalk~lenephosphonic acid
and phosphoric acid. No sulphuric acid is disclosed in EP-A-411 708.
EP-B-047 150 discloses aminomethylenephosphonic acid solutions
containing at least 10% by weight of the total solution of active
35 phosphonic acid, i.e. aminomethylenephosphonic acid and acids such as
sulphuric acid, as a non-oxidizing mineral acid. No surfactants are
disclosed in EP-B-047 150.
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EP-A-346 667 discloses stabilized aqueous mixed permonosulphuric
acid/sulphuric acid solutions containing a sequestrant such as a
phosphorus-containing compound, commercially available from
5 Monsanto under the trade name Dequest, in an amount of from 0.01 %
to 1 % by weight and a stabilizing quantity of an added metal
compound. The solutions of EP-A-346 667 are suitable for use to strip
photoresist residues from semiconductor surfaces. The solution of
permonosulphuric acid may be produced by reacting sulphuric acid and
hydrogen peroxide. EP-A-346 667 further discloses that surfactants
may be added and that a suitable quantity is from 20 to 500 ppm by
weight of the solution.
J 06340617, (Derwent abstract), discloses safe peracetic acid
15 compositions comprising peracetic acid, hydrogen peroxide, acetic acid,
a stabilizer such a pyrophosphonic acid or diethylene triamine penta
methylenephosphonic acid, and sulphuric acid. An example is disclosed
with 0.2% by weight of sulphuric acid and 0.2% by weight of 1-
hydroxyethylidene-1,1-diphosphonic acid. No surfactants are disclosed.
Summarv of the invention
The present invention encorr r~sses an acidic aqueous composition
comprising sulphuric acid, a chelating agent having a pKa not higher
than 4 and at least 0.1 % by weight of the total composition of a
surfactant.
In a preferred embodiment the acidic aqueous compositions of the
present invention further comprise a thickening surfactant system
comprising a quaternary ammonium compound and a short chain amine
oxide. In a preferred embodiment, the acidic aqueous compositions of
35 the present invention further comprise a source of active oxygen, or
mixtures thereof.
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The present invention also encompasses a process of treating a hard-
surface, especially toilet bowls, wherein an acidic aqueous composition
comprising sulphuric acid and a chelating-agent having a pKa not higher
than 4, is contacted to said surface, thereby delivering improved
5 surface appearance to said surface.
Detailed descrintion of the invention
. . ._
The compositions of the present invention are aqueous liquid
compositions comprising, as a first essential ingredient, sulphuric acid.
15 Sulphuric acid suitable to be used herein is, for example, the one
commercially available from MERCK.
The compositions of the present invention comprise from 0.1% to 20 %
by weight of the total composition of sulphuric acid, preferably from
2 0 O. 2 % to 1 5 % and more preferably from 0. 5 % to 1 0% .
The compositions of the present invention are acidic. Accordingly, the
compositions herein are formulated at a pH between O to 6, preferably
at a pH between O and 4 and more preferably at a pH between O and 2.
25 Acidity further contributes to formulate compositions according to the
present invention which exhibit good mineral encrustations removal
performance while having also good disinfecting properties. The
compositions of the present invention apart from sulphuric acid may
further comprise other organic and/or inorganic acids. Particularly
30 suitable organic acids to be used herein are aryl and/or alkyl sulfonate,
such as methane sulfonic acids, succinic acid and the like. Particularly
suitable inorganic acids are further phosphoric acid, nitric acid and the
like.
3 5 The compositions of the present invention are aqueous liquid
compositions comprising, as a second essential ingredient, a chelating
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agent having a pKa being not higher than 4, or mixtures therebf,
preferably having a pKa being not higher than 2.
The chelating agents to be used according to the present invention
5 should have a pKa not higher than 4, preferably not higher than 2, so
that they are not totally protonated in the compositions of the present
invention which are formulated at very low pH values. In other words,
the chelating agents of the present invention are negatively charged at
very low pH value, for instance, at pH 1 and thus contribute to inhibit
10 the formation and subsequent precipitation of poorly water soluble
calcium salts such as calcium sulfate.
Below is showed the mechanism of action of chelating agents according
to the present invention when applied in a very acidic composition:
2H+ + S042-+ Ca2+ + CaC03 + =~ H20 + Ca2+S042~ + C02 + (ChelantlM~
Chelant Ca2 +
pH = 0.5 - Chelatin~ a~ent is p~oLundl~d locally pH ~ 1 - Chelatin~ al3ent is partially
l,npru Lunated
Protons of sulfuric acid are able to dissolve calcium carbonate crystals
thus liberating Ca+ + and C03-- ions into the composition in contact
with the surface of, for instance, a toilet bowl to be treated. The C02
release plus the water formation as indicated in the above reaction
contribute to increase the local pH from about 0.5 to about 1 where the
chelating agents of the present invention having a pKa not higher than 4
become partially unprotonated and therefore inhibit/reduce calcium
sulfate precipitation by binding Ca+ + in soluble complexes. Also, they
could bind Ca+ + ions of the encrustation itself, thus helping its
2 5 removal.
Suitable chelating agents having a pKa being not higher than 4 are
phosphonate-based chelants having a number of phosphonate groups
J ranging from 1 to 6 and being preferably selected from the following
group, or mixtures thereof:
1 ) amino poly alkyl phosphonic acids with the following formula:
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[NX2]al ~ [(CH2)nNXm]a2- [(CH2)2 NX2]a3
where:
X = Methylene Phosphonic Acid (CH2H2P03)
n = O to 1
m = 1 to 3
a1 = Oto 1
a2 = 1 to 4
a3 = Oto 1
' - --
2) metaphosphoric acid (HP03)n
3) pyrophosphoric acid (H4P207)-
4) methylidene di phosphonic acid CH2(H2P03)2
Suitable amino poly alkyl phosphonic acids are diethylenetriamine penta
methylene phosphonic acid, commercially available from Monsanto
20 under the trade name Dequest ~ 2066A; amino trimethylene
phosphonic acid c~mmercially available from Albright&Wilson under the
trade name Briquest (~301 -50A; tetraethylene pentaamine hepta
methylene phosphonic acid commercially available from Albright&Wilson
under the trade name Briquest (~ 785; pentaethylene hexaamine octa
25 methylene phosphonic acid commercially available from Albright&Wilson
under the trade name Briquest ~ 8106.
Preferred amino poly alkyl phosphonic acid to be used herein is
diethylenetriamine penta methylene phosphonic acid.
Metaphosphoric acid suitable to be used herein may be the one
co, . ,. "ercially available from Carlo Erba.
Pyrophosphoric acid suitable to be used herein may be the one
35 commercially available from Carlo Erba.
The compositions of the present invention comprise from 0.05% to 3%
by weight of the total composition of a chelating agent having a pKa
not higher than 4, or mixtures thereof, preferably from 0.05% to 2% by
40 weight and more preferably from 0.05% to 1 %.
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~ =
The compositions of the present invention are aqueous liquid
compositions comprising at ~east 0.1 % by weight of the total
composition of a surfactant, or mixtures thereof. The compositions of
the present invention comprise surfactants to provide further cleaning
b 5 benefits. Also, surfactant systems can be used to provide viscosity tothe compositions herein, and that is desirable since the compositions
herein are likely to be used on inclined surfaces such as bath tubs, sinks
or toilet bowls. Thickened compositions have a better cling onto inclined
surfaces, thus a longer residence time for the composition to remove
mineral encrustations.
Thus the surfactants of the present invention may be any surfactant
selected from the group of anionic, nonionic, zwitterionic and cationic
surfactants in amounts ranging up to 50 % by weight of the total
composition, preferably from 0.1% to 30% and more preferably from
0.1% to 10%.
Suitable anionic surfactants include alkyl or alkylene sulfate or
sulfonates, alkyl or alkylene ether sulfates or sulfonates, linear alkyl
2 0 benzene sulfonate and the like. Suitable cationic surfactants include
quaternary ammonium salts. Suitable nonionic surfactants for use herein
include ethoxylated carboxylic acids, amine oxides and alcohol
ethoxylates. Emulsions of nonionic surfactants, such as in co-pending
European patent application EP 598 692, are also suitable to provide
2 5 pseudoplastic and thixotropic compositions, which allow excellent
spreading and clinging characteristics on dry surfaces.
A suitable thickening surfactant system highly preferred herein that
leads to excellent spreading and clinging on wet surface is constituted
by mixtures of a quaternary ammonium compound, or mixtures thereof,
together with a short chain amine oxide, or mixtures thereof. Said
compositions are Newtonian. By "Newtonian" it is meant herein a
composition which has the same viscosity within a very wide range of
applied shear stresses.
Suitable quaternary ammonium compounds to be used herein are
quaternary ammonium compounds wherein one or two of the
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hydrocarbon groups linked to nitrogen are a linear or branched alkyl
group of 6 to 30 carbon atoms, preferably of 10 to Z5 carbon atoms
and more preferably 12 to 20 carbon atoms, satur,ated or unsaturated,
and wherein the other hydrocarbon groups (i.e. three when one
5 hydrocarbon group is a long chain hydrocarbon group as mentioned
hereinbefore or two when two hydrocarbon groups are long chain
hydrocarbon groups as mentioned hereinbefore) linked to the nitrogen
are independently substituted or unsubstituted, linear or branched, alkyl
chain of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon
10 atoms and more preferably are methyl groups. In the embodiment of
the present invention where as sources of active oxygen, persulfate
salts or mixtures thereof, are used the quaternary ammonium compound
is preferably a non-chloride quaternary ammonium compound. The
counterion used in said quaternary ammonium compounds are
15 compatible with any source of active oxygen if present and are selected
from the group of fluoride or methyl sulfate, or methylsulfonate, or
hydroxide and the like. Particularly preferred to be used herein are
trimethyl quaternary ammonium compounds like myristyl trimethyl
ammonium methylsulfate, cetyl trimethyl ammonium methylsulfate
2 0 and/or tallow trimethyl ammonium methylsulfate. Such trimethyl
quaternary ammonium compounds are commercially available from
Hoechst, or from Albright & Wilson under the trade name EMPIGEN CM
~.
2 5 The compositions according to the present invention comprise up to
20% by weight of a quaternary ammonium cornpound, or mixtures
thereof, preferably of from 0.1% to 15%, more pr0ferably of from 0.1%
to 10% and most preferably of from 1% to 5%.
30 Suitable short chain amine oxides to be used herein are amine oxides
having the following formula R1 R2R3N0 wherein R1 is a C6 to C10
alkyl group, preferably a C8 to C10 alkyl group and wherein R2 and R3
are independently substituted or unsubstituted, linear or branched alkyl
groups of from 1 to 4 carbon atoms, preferably of from 1 to 3 carbon
35 atoms and more preferably are methyl groups. R1 may be a linear or
branched alkyl group, being saturated or unsaturated. Suitable short
chain amine oxides for use herein are preferably compatible with any
-
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source of active oxygen if present. Preferred short chain amine oxides
for use herein are for instance natural blend C8/C 10 amine oxide
available from Hoechst.
,, 5 The compositions according to the present invention comprise up to
15% by weight of a short chain amine oxide, or mixtures thereof,
preferably of from 0.1% to 10% more preferably of from 0.1% to 5%
and most preferably of from 0.1 % to 3%.
The total level of thickening surfactant system, i.e. of quaternary
ammonium compound and of short chain amine oxide, to be used in a
given aqueous acidic composition of the present invention depends on
the thickening desired for said composition, said level being up to 20%,
preferably between 1 % and 15%, and more preferably between 1 % and
6%. Suitable weight ratios of said short chain amine oxide to said
quaternary ammonium compound range from 1:2 to 1:100, preferably
from 1 :4 to 1 :30 and more preferably from 1: 10 to 1 :20. Desired
viscosity herein ranges from 150 cps and up at 20~C, preferably of
from 250 cps to 1500 cps and more preferably of from 250 cps to 900
cps, when measured with a Brookfield viscometer at 60 rpm with a
spindle n~ 2 or with the Carri-med rheometer at 50 dyne/cm2.
In a preferred embodiment the compositions of the present invention
may comprises a source of active oxygen, or mixtures thereof, which is
an acid-stable bleach. By "acid-stable" it is meant herein a compound
which is stable in the acidic environment of the compositions herein. By
stable, it is meant herein that a composition of the present invention
further comprising a source of active oxygen, or mixtures thereof, such
as persulfate salt, pler~rdbly does not undergo more than 50%
persulfate loss, in six months at room temperature (20~C-25~C).
Persulfate concentration can be measured by titration with potassium
permanganate after reduction with a solution containing ammonium
ferrous sulphate. Said stability test method is well known in the art and
is reported, for example, on the technical information sheet of Curox~3
commercially available from Interox. Alternatively persulfate
concentration can also be measured using a chromatography method
described in the literature for peracids (F. Di Furia et al., Gas-liquid
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Chromatography Method for Determination of Peracids, Analyst, Vol
113, May 1988, p 793-795).
The source of active oxygen according to the present invention acts as
an oxidizing agent, it increases the ability of the cornpositions to remove
5 colored stains and organic stains in general, to destroy malodorous
molecules and to kill germs. Suitable sources ol active oxygen are
hydrogen peroxide or sources thereof. As used herein a hydrogen
peroxide source refers to any compound which produces hydrogen
peroxide when said compound is in contact with water. Suitable water-
10 soluble inorganic sources of hydrogen peroxide for use herein includepersulfate salts (i.e. dipersulfate and monopersulfate salts), persulfuric
acid, percarbonates, metal peroxides, perborates and persilicate salts.
In addition, other cl~sses of peroxides can be usedl as an alternative to
hydrogen peroxide and sources thereof or in combination with hydrogen
15 peroxide and sources thereof. Suitable classes include dialkylperoxides,
diacylperoxide, performed percarboxylic acids, organic and inorganic
peroxides and/or hydroperoxides. Suitable organic
peroxides/hydroperoxides include diacyl and dialkyl
peroxidesJhydroperoxides such as dibenzoyl peroxide, t-butyl
2 0 hydroperoxide, dilauroyl peroxide, dicumyl peroxide, and mixtures
thereof. Suitable preformed peroxyacids for use in the compositions
according to the present invention include diperGxydodecandioic acid
DPDA, magnesium perphthalic acid, perlauric acid, perbenzoic acid,
diperoxyazelaic acid and mixtures thereof.
25 Persulfate salts, or mixtures thereof, are the preferred sources of active
oxygen to be used in the compositions according to the present
invention. Preferred persulfate salt to be used herein is the
monopersulfate triple salt. One example of monopersulfate salt
commercially available is potassium monopersulfale commercialized by
3 0 Peroxide Chemie GMBH under the trade name Curox(~), by Degussa
under the trade name Caroat and from Du Pont under the trade name
Oxone. Other persulfate salts such as dipersulfa1:e salts commercially
available from Peroxide Chemie GMBH can be used in the compositions
according to the present invention.
3 S
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i3
The preferred compositions of the present invention which comprise a
persulfate salt such as monopersulfate, when used to treat hard
surfaces, especially toilet bowls, exhibit outstanding soil discoloration
together with a germicidal action.
The compositions according to the present invention may comprise up
to 30% by weight of the total composition of said source of active
oxygen, or mixtures thereof, preferably from 0. 1% to 30%, more
preferably from 0.1% to 20%, and most preferably from 0.1% to 15%.
The compositions according to the present invention are aqueous. The
compositions according to the present invention comprise from 40% to
99% by weight of the total composition of water, preferably from 60%
to 95%, most preferably from 70% to 90%. Deionized water is
15 preferably used.
Depending on the end use envisioned, the compositions according to
the present invention may further comprise a variety of other
ingredients including organic or inorganic alkalis, dyes, optical
20 brighteners, builders, other chelants, pigments, colorants, enzymes, dye
transfer inhibitors, solvents, buffering agents, stabilizers, perfumes and
the like.
The present invention further encompasses a process of treating a hard-
25 surface wherein an acidic composition comprising sulphuric acid and achelating agent having a pKa being not higher than 4, is contacted to
said surface, thereby delivering improved surface appearance to said
surface.
30 By " improved surface appearance to said surface" it is meant herein
that the shine, and/or cleaning performance, i.e. mineral encrustation
removal performance, delivered to the surface treated with the
compositions of the present invention is improved. In other words, it
has been found that the shine and/or cleaning performance delivered to
3 5 the hard-surfaces treated with a composition of the present invention
comprising sulphuric acid and a chelating agent having a pka not higher
than 4, is improved as compared to the shine and/or cleaning
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14
performance delivered when treating said hard-surfaces with the same
composition but without any such chelating agent.
Actually, the present invention is based on the finding that the
5 effectiveness of the compositions of the present invention on mineral
encrustations, is increased as compared to the same composition
without any such chelating agent.
Any of the compositions already mentioned herein before may be used
10 in the process of treating hard-surfaces according to the present
invention .
in the process of the present invention said composition may be used
neat or in its diluted form. By "in its diluted form" it is meant herein that
15 said compositions may be diluted with water up to 99% of water. Said
dilution may occur either before, after or while said composition is
applied to a hard-surface.
The compositions herein find a preferred application in the cleaning of
2 0 toilet bowls and bath tubs. While cleaning toile~ bowls compositions
according to the present invention may be diluted while or after they are
applied to the surface to be cleaned. For example, said compositions
may be dispensed from a container onto said hard-surface, then diluted
in water and left to act onto said surfaces, then removed by rinsing or
2 5 flushing.
As used in the foregoing paragraphs, the expression '-tl~dLil~9" includes
mineral encrustations removal as the composition used in the process
according to the present invention comprises sulphuric acid, washing as
30 the compositions used in the process according to the present invention
may further comprise surfactants and/or bleaching as said compositions
may also comprise a source of active oxygen, preferably persulfate
salts.
35 The present invention is further illustrated by the following examples.
ExamDles
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Compositions are made which comprise the listed ingredients in the
Iisted proportions (weight %).
,~ 5 Compositions #1 #2 #3 #4
#5
(% by weight)
Sulphuric acid 6 6 6 6
Curox(~) 6 6 6 6
C16 trimethyl ammonium
methylsulfate 4 4 4 4
C8/C10 amine oxides 0.2 0.2 0.2 0.2
0.2
Diethylene triamine penta
(methylene phosphonic acid) -- 0.1 --
Amino trimethylene phosphonic
acid -- -- 0.1 --
Metaphosphoric acid -- -- -- 0.1
25 - -
Pyrophosphoric acid -- -- -- --
0.1
Water and minors up to 100
30 pH 0.5 0.5 0.5 0.5
0.5
viscosity (m Pa s) 300 300 300 300
300
-
35 * Curox(3 is one of the co"""ercial names of monopersulfate salts.
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16
Compositions #2, #3, #4 and #5 are representative of the present
invention. They are acidic aqueous compositions comprising sulphuric
acid, surfactants and a chelating agent having a pKa being not higher
than 4. Composition #1 is taken as a reference, it is free of chelating
5 agent having a pKa being not higher than 4.
A)
The above compositions were evaluated for their surface appearance,
i.e. cleaning and shine performance, on white ceramic tiles soiled with
10 typical toilet mineral encrustations. The ceramic tiles were soaked for 2
minutes in the different compositions mentioned herein before (neat
conditions~. Then the tiles were rinsed and dried.
To evaluate the performance of the compositions, a sets of
spectophotometric measurements were made. This analysis can be
meant as a technical measure of surface appearance. In fact,
20 reflectance spectra (L value) was measured on sailed tiles (A), on tiles
after products application (B) and on completely shiny/cleaned tiles (C).
The measure of composition performance (index) was calculated using
the following formula:
(B) (A) x100
The results were as following:
Compositions #1 #2 #3 #4
#5
Index 62 95 89 87
"
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The index represents the measure of tile surface appearance after
product application. Index 0 means completely soiled tile, whilst index
100 means completely shiny/cleaned tile.
, 5 Accordingly, it has been observed that the compositions of the present
invention (compositions #2, #3, #4 and #5) exhibit improved cleaning
performance and improved shine, as compared to composition #1 which
is free of a chelating agent having a pKa being not higher than 4.
B)
Above compositions #1 and #2 were further evaluated to compare the
residues (i.e., calcium sulfate) left after application on black ceramic
tiles soiled with calcium carbonate only. Said compositions were poured
on these inclined ceramic tiles and let act for 3 minutes (neat
conditions). Then the tiles were rinsed and dried.
To evaluate the performance of the compositions, a sets of visual
gradings were made. This analysis can be meant as a measure of
product residuality on surfaces from a consumer standpoint.
The results were as following:
Compositions #1 #2
Residues left index* 100 65
* index 100 is assumed as reference value
Accordingly, it has been observed that the composition of the present
3 0 invention (composition #2) exhibits a much lower residuality as
compared to composition #1 which is free of a chelating agent having a
pKa being not higher than 4. Indeed less calcium sulfate residues were
left on the surfaces treated with the composition of the present
J invention.
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18
Also the compositions of the present inventjon ( compositions #2, #3,
#4 and #5) were found to be stable over long periods of time. Indeed,
these compositions had not more than 10% loss after 1 month at room
temperature.
