Note: Descriptions are shown in the official language in which they were submitted.
IR 5253
MICROEMULSION CLEANING COMPOSITION COMPRISING A GLYCOL
MONO-ALKYL ETHER
Rel~t~rl Applic~ti~n
This ap,~" 'icn is a continuation in part a~ n of U.S. Serial No.
08/048,538 filed 4114/93.
Field of the Invention
This invention relates to microemulsion cleaning uu"~posilions having
enhanced degrees of oil uptake and superior cleaning pe,lun"a"ce and in particular
10 to cleaning cor",uosilions that leave lower surface residues following their use.
Backçlmllnd of the Invention
Liquid detergent .,or",uosilions in emulsion form have been employed as all-
purpose de~ lyelll:~ for cleaning hard surfaces, such as, painted woodwork, bathtubs,
sinks, tile floors, tiled walls, linoleum, paneling and washable wallpaper. Taking
15 advantage of the mechanism of soil removal by en ll' ' ~i~n, microemulsions were
developed as a more efficient method of removing l;~JO~JII 'i~/nldlt:lials from substrates.
These microemulsions include a lipophile, a surfactant, a cosurfactant and water.
They are a thermodyna", 'Iy stable phase in which the micelles have a particle size
of less than 100nm (nar,o",~ ), are lldnS~Udl~:lll with no Tyndall scattering and do
20 not separate over long periods of time. Microemulsions can solubilize oil without the
use of expensive hyd~ul~upes or vigorous mixing. They show very low interfacial
tensions with oil and so will spread on soil surfaces aiding cleaning.
Microemulsions have certain disadVdlllayt~s which make their:,, ' n to
practical problems difficult and often u"p,~di-,~dLle. For example, in order to apply this
25 It:~:hnoloy~ to a particular problem, it is necessary to determine the ternary phase
diagram for said system. In addition careful .,onside,dlion must be taken of thesurfactant and cosurfactant to be used. Microemulsions are sensitive to electrolytes
and the phase behavior of each system must be well understood when diluting it.
They are sensitive to oil chain length and foaming at high conce"l, 15 of surfactant.
M. Loth et al in U.S. 5,075,026 and in U.S. 5,082,584 disclosed an
improvement in microemulsion co,,,,uosiliulls containing an anionic detergent, acosurfactant, a l,Jd,ucdrbon and water comprising the use of a water-insoluble
odoriferous perfume as the essential h~dlucd~boll ingredient. The cosurfactants of
5 this reference have sub~ld"li.."y no ability to dissolve oily or greasy soil and are
selected from the group consisting of, among other entities, water-soluble alkanols
have 3 to 4 carbon atoms, polypropylene glycol ethers, and monoalkyl ethers and
esters of ethylene glycol or propylene glycol having 1 to 4 carbon atoms.
M. Loth et al in U.S. 5,076,954 deli"edl~d a conce"l, d stable,
1 0 microemulsion, cleaning co",,uo~ilion co,,,,ulisillg synthetic organic detergent,
cosurfactant, water and water-insoluble perfume as an essential hydrocarbon
ingredient in an amount sufficient to form a dilute oil-in water (o/w) microemulsion
COIll, ~' 'icn. The cosurfactants of this reference are selected from the group
consisting of, among other compounds, water soluble alkanols, of 2 to 4 carbon
1 5 atoms, poly~,,u,uylene glycol of 2 to 18 propoxy units, a monoalkyl ether of a lower
glycol of the formula RO(X)nH wherein R is C1-4 alkyl and X is CH2CH2O,
CH(CH3)CH2O or CH2CH2CH2O and n is from 1 to 4.
P.J. Durbut et al in U.S. 5,û35,826 described a liquid detergent co~ n
which in liquid crystal form comprises one or more nonionic d~t~yerlb with lesser
20 amounts of anionic or cationic surfactants, a cosurfactant, such as tripropylene glycol
butyl ether, a solvent for the soil, such as, an i::~Opdldii' I (9-1 1 carbons) or methyl
cocoate and water as the major cor,,,uollelll
M. Loth et al in U.S. 5,108,643 described an aqueous microemulsion
uoill,uli:,illg an anionic and/or nonionic synthetic organic detergent, water-insoluble
25 perfume, water and cosurfactant where the cosurfactant adjusts interfacial
colliulllldlioll to reduce interfacial tension between dispersed and continuous phases
of said d~t~lye~ls, perfume and water and therefore produces a stable
microemulsion. This coi"po~ ion does not contain any solvents for oils and greases
other than the perfume.
M. Kahlweit reviewed the state of the art in the field of microemulsions in
Science, Volume 240, pages 617-621, April (1988).
It is an object of this invention to provide microemulsion cleaning formulationswhich show higher degrees of oil uptake and superior cleaning performance when
compared with systems ~ r~e"ldlive of the prior art.
It is another object of this invention to provide microemulsion cleaning
formulations which are effective with smaller amounts of active i"yredi~"l~ reducing
the amounts of residues left after cleaning over that obtained using prior art systems.
Other objects will become apparent to those skilled in the art upon a further
reading of the ~.e-,h'' -n.
SummRry of the Invention
A microemulsion cleaning co",l,o~iti;i,) meeting the objects given above has
been developed which comprises on a weight basis of the entire compo~ilion:
(a) from 1 to 40~/O of an anionic organic surface active agent;
(b) from 0 to 40~/O of a nonionic organic surface active agent;
(c) from 0 to 5~/O of an inorganic electrolyte;
(d) from 1 to 40~/O of a cosurfactant having the structure RO(X)nH where R is
an alkyl radical having 6 to 9 carbon atoms, X is an ethoxy, propoxy or isopropoxy
monovalent radical, wherein n is 1 to 4, more preferably 2 to 3; and
ZO (e) the remainder, sufficient water to bring the total co"".o~ilion to 100~/O by
weight, wherein the cor"po~ilion ~ n 'Iy contains 0.4 to 10 wt. ~/O of a perfume.
It will be u,)de,~lood by those skilled in this art that the above-described
CO~ Ositiol1 may addilion 'Iy contain as optional co"".ont:"ls such materials as dyes,
perfumes, foam controllers, II,i~ih~ne,~ and the like. As used herein, the term
"perfume" is used in its ordinary sense to refer to and include any non water-soluble
fragrant substance or mixture of substances including natural (i.e., obtained byextraction of flower, herb, blossom or plant), artificial (i.e., a mixture of natural oils or oil
constituents) and synthetic (i.e., a single or mixture of synthetically producedsubstance) odoriferous substances. Typically perfumes are complex mixtures of
blends of various organic compounds, such as, esters, ketones, hydrocarbons,
lactones, alcohols, aldehydes, ethers, aromatic compounds and varying amounts ofessential oils (e.g., terpenes) such as from 0~/O to 80%, usually from 10% to 70~/O by
weight, the essential oils themselves being volatile odoriferous compounds and also
5 serving to dissolve the other cum~uonerll ~ of the perfume. The precise coll~ n of
the perfume has no particular effect on cleaning performance so long as it meets the
criteria of water i""" ~ 'ity and pleasant odor. Although perfume is not, per se, a
solvent for greasy or oily soil, - even though some perfumes may, in fact, contain as
much as 80% of terpenes which are known as good grease solvents - they have the
10 capacity to enhance oil uptake in the Co",pO~ iolls of this invention.
Another ingredient that may be optionally added to the uo~luosilion of this
invention is an inorganic or organic salt or oxide of a multivalent metal cation,
particularly Mg~. The metal or oxide can provide several benefits including
improved cleaning pelfo,l"dl,ce in dilute usage. Magnesium sulfate, either anhydrous
15 or hydrated, is especially preferred as the magnesium salt. Other polyvalent metal
ions that can also be used include aluminum, copper, nickel, iron and the like.
When inclusion of a foam su,u~ur~ssdlll in the claimed Col"~ o~ilions is desired,
minor amounts, i.e., from 0.1 ~/O to 2.0%~ preferably from 0.25% to 1.0% by weight of the
uum, - n of a fatty acid or fatty acid soap having 8 to 22 carbon atoms can be
20 i~uc,r,uo~dled.
Examples of the fatty acids which can be used as such or in the form of soaps
include, distilled coconut oil fatty acids, "mixed vegetable" type fatty acids (e.g., those
of high pelu~lltdgt:s of saturated, mono- and/or polyunsaturated C18 chains) oleic
acid, stearic acid, palmitic acid, ~icosdnoic acid, and the like. Generally those fatty
25 acids having from 8 to 22 carbon atoms therein are operative. The instant
co",uo~ilions do not contain any cationic, nonionic or anionic emulsifier surfactants
such as those set forth at Column 8, line 16 to line 61 of U.S. Patent 5,171,475, which
is hereby incorporated by reference.
No specific mixing techniques or equipment are required for the p,~pa, ~n of
these cleaning co"~pobilions. The order of mixing the various co",,uone"l~ is not
narrowly critical and generally the various materials can be added to a suitablecontainer sequentially or all at once with conventional agitators.
The temperatures used to prepare the claimed cor,,,uo~iliuns and to clean
products with them is not critical, ambient temperatures being sufficient. For removing
oily soils or deposits from surfaces a range of 5 to 50~C is preferred.
The range of pH of the ~.or",uo:,itio,- is not critical and can be 5.0 to 9.0 or even
from 2.0 to 13Ø
Although one can use from 1 to 40~/O of the range of anionic organic surface
active agent, it is preferred to use 3 to 20% by weight. This is also the preferred range
for nonionic surface active agent, when used.
The amount of cosurfactant employed is preferably 1 to 40~/O with a range of 1
to 15% being even more preferred.
The preferred electrolyte is sodium chloride but is not narrowly critical and soother metal salts can also be used. For example alkali metals, including potassium
and lithium, alkaline earth metals, including barium, calcium and strontium and
polyvalent metals, such as, aluminum, copper, nickel, iron and the like may be used
with such anions as halides, sulfates, nitrates, hydroxides, oxides, acetates and the
like. The preferred halide is chloride although bromide, iodide or fluoride can be used
if desired. The preferred quantitative limits for the el~,t,ulyt~,~ is 0 to 5% with 0 to 1%
being particularly preferred.
Suitable organic surface active agents include water-soluble, non-soap,
anionic clt:t~,ge"ts as well as mixtures of said anionic detergents with water-soluble
25 nonionic and polar nonionic dt~lely~llt;Exemplary anionic dt~te,ye"la include those
compounds which contain an organic hydrophobic group containing 8 to 22 carbon
atoms and preferably 10 to 18 carbon atoms in their molecular structure and at least
one water-so~ 9 group, such as, sulfonate, sulfate or carboxylate. Usually, the
hydluphobic group, will comprise a 8-22 carbon alkyl, alkenyl or acyl group. These
d~l~,ye"l:, are employed in the form of water-soluble salts and the salt-forming cation
is usually sodium, potassium, ammonium, magnesium, 2-3 carbon mono-, di- or
tralkanolammonium cations.
Examples of anionic sulfate dt:l~ly~l,h are the 8-18 carbon alkyl sulfate salts
5 and alkyl ether polyethenoxy sulfate salts having the formula R(oc2H4)noso3M
wherein R is an alkyl group having 8-18 carbon atoms, n is 1 to 12 and M is a
5nl~ 9 cation, e.g., sodium, potassium, ammonium, magnesium and mono-, di-
and triethanol ammonium ions. The alkyl sulfate salts may be obtained by reducing
glycerides of coconut oil or tallow and neutralizing the product with bases derived
10 from metals in Groups 1, ll or lll of the Deming Periodic Table. The alkyl ether
polyethenoxy sulfates are obtained by sulfating the cond~nsdlion product of ethylene
oxide with an 8-18 carbon alkanol and neutralizing the product. Preferred alkyl
sulfates and alkyl ether polyethenoxy sulfates contain 10 to 16 carbon atoms in the
alkyl moiety. Particularly preferred alkyl sulfates are sodium lauryl sulfate and sodium
15 myristyl sulfate.
When present, the water-soluble nonionic surfactants that are employed are the
colldt:" n product of an organic aliphatic or alkyl aromatic h~dlupllobic compound
having a carboxy, hydroxy, amido or amino group with a free hydrogen attached to the
nitrogen atom can be condensed with ethylene oxide or with the polyhydration
20 product thereof, polyethylene glycol, to form a nonionic detergent. The length of the
polyethenoxy chain can be adjusted to achieve the desired balance between the
h~dlupllobic and hydrophilic elements (HLB) and such balances may be measured byHLB numbers.
Suitable nonionic surfactants are the condensdlion products of a higher alcohol
25 containing 8 to 18 carbon atoms in a straight or branched chain configuration~ondtl"sed with 0.5 to 30 moles of ethylene oxide. Preferred compounds are a 9 to 11
carbon alkanol ~Ihu~ ' (5EO) and a 12 to 15 carbon alkanol ~Iho~dldl~ (7EO).
These preferred compounds are co"""e,u;al'y available from Shell Chemical Co.
under the l,ddena",e~, Dobanol 91-5 and Neodol 25-7.
Another group of suitable nonionic surfactants, sold under the lldde:ndllle
Pluronics, are cond~"sdlion products of ethylene with the condensdt;on products of
propylene oxide and propylene glycol.
Other suitable surfactants are the ~.olyc~ ,J~nsdlion products of ethylene oxideand alkyl phenols, like nonyl phenol.
For the cosurfactants in this invention having the structure RO(X)nH where R, X
and n are as defined above which are particularly useful over temperatures of 5C and
43C wherein x is an alkylene or dialkylene group having 1 to 4 carbon atoms, more
preferably 2 to 3 carbon atoms. Useful cosurfactants are: ethylene glycol monohexyl
ether, ethylene glycol monoheptyl ether, ethylene glycol monooctyl ether, ethylene
glycol monononyl ether, diethylene glycol monohexyl ether, diethylene glycol
~,,onohe,ulyl ether, diethylene glycol monooctyl ether, triethylene glycol ",onoht:,~yl
ether, propylene glycol monohexyl ether, isou~up~u,u~ ne glycol monohexyl ether and
the like. These surfactants may be sy.,ll,esi~ed by condell~i"g an alkanol having 6 to
9 carbon atoms with ethylene oxide, 1,2-propylene glycol, or 1,3-propylene glycol
respectively.
Brief Descri~tion of the Drawin~s
Figure 1 a is a ternary phase diagram showing dodecane uptake in a system
containing ethylene glycol ",onohe,~yl ether (C6E1) as cosurfactant.
Figure 1 b is a ternary phase diagram showing dodecane uptake in a system
containing diethylene glycol ",onoh~,~yl ether (C6E2) as cosurfactant.
Figure 2a is a ternary phase diagram showing dodecane uptake in a system
containing ethylene glycol monobutyl ether (C4E1) as cosurfactant.
Figure 2b is a ternary phase diagram showing dodecane uptake in a system
containing diethylene glycol monobutyl ether (C4E2) as cosurfactant.
Figure 3 is a two di",ellsiondl graph showing dodecane uptake in a system
containing either diethylene glycol ",onolle,~;l (C6E2) or monobutyl ether (C4E2) as
cosurfactant with a mixture of anionic and nonionic surfactants.
Figure 4 is a two dil"ensiul1al graph showing triolein uptake as a function of the
amount of dodecane solubilized in an ethylene glycol monohexyl ether (C6E1)
system.
Figure 5 is a two dimensional graph showing triolein uptake as a function of theamount of dodecane 50111' ": ~ in a diethylene glycol monohexyl ether (C6E2)
system.
Figure 6 is a two di",el1siondl graph showing neat grease cleaning of two
prototype microemulsions.
Figure 7 is a two dimensional graph showing grease cleaning with diluted
1 û microemulsions.
Detailed Description of the Invention
The invention is further described in the examples which follow. All parts and
pel~:~"ldg~s are by weight unless otherwise specified.
FY:I~)IP 1
The 50lll' ' ~g power of systems employing ethylene glycol monohexyl ether
(~vailable as Hexyl Cellosolve from Union Carbide Chemicals and Plastics Co. Inc.)
and diethylene glycol ",onohexyl ether (available as Hexyl Carbitol from Union
Carbide Chemicals Co. Inc.) as cosurfactants were compared with systems employing
ethylene glycol monobutyl ether (available as Butyl Cellosolve from Union Carbide
Chemicals and Plastics Co. Inc.) and diethylene glycol monobutyl ether (available as
Butyl Carbitol from Union Carbide Chemicals and Plastics Co. Inc.) using n-dodecane
as the material being solubilized. Sol~ icn capacities for n-dodecane, i.e., theamount of n-dodecane which can be solllh~ d in a microemulsion so that the
dispersion remains homogeneous, I,dl1spa,~r,l and stable, were plotted in Figures 1a-
b and 2a-b. The systems described are co",posed of 0.15M NaCI (aqueous) brine,
sodium lauryl sulfate (as the surfactant SLS) and either ethylene glycol monohexyl
ether (1a), diethylene glycol monohexyl ether (1b), ethylene glycol monobutyl ether
(2a) or diethylene glycol monobutyl ether (2b). The n-dodecane sohl' " -n
capacities are shown in the form of contours of equal oil uptake plotted on the
brine/SLS/cosurfactant triangular phase diagram. Note that Figures 1a-b and 2a-brepresent partial phase diagrams only going up to 50~/0 SLS and 50~/O cosurfactant.
The percentages shown on the contours were calculated from the equation:
~/0 dodecane = m~cc dode~ne x 1 00~/O (1 )
mass sum of brine SLS and cosurfactant
Thus in Figure 1a the 2.5% contour lies on a coi"~,o~ilion point of 85% brine 11%
SLS and 4~/O ethylene glycol monohexyl ether (C6E1). This means that in 100g of an
85% brine 11% SLS 4~/O C6E1, 2.5g of dodecane may be sol~h ' ~d before the
mixture separates into two liquid phases.
The superior solll i~n performance of systems employing ethylene glycol
",onoh~,~yl ether and diethylene glycol monohexyl ether over systems with ethylene
glycol monobutyl ether and diethylene glycol monobutyl ether is demonstrated by
co" ,~ a, i"g Figures 1 a and 1 b with 2a and 2b. For example Figure 1 a shows that a
.;o""~o:,ilion of 90~/O brine 5.0~/O SLS and 5~/O ethylene glycol monohexyl ether can
solubilize 5~/O dodecane; a coi"~.osilion with diethylene glycol ",onohe,~yl ether
instead can solubilize 1% dodecane. Neither ethylene glycol monobutyl ether nor
diethylene glycol monobutyl ether systems in like conlr -ns were able to solubilize
any significant amounts of dodecane. In more conce"t,dl~d systems having 12.5%
SLS and 12.5% cosurfactant the ethylene glycol monohexyl ether system can
solubilize 6% dodecane. Like systems with ethylene glycol monobutyl ether and
diethylene glycol monobutyl ether are able to solubilize only 2% and 1% dodecane,~spe~ Y
The ability of a system to solubilize significant amounts of oil with lower
con~;~"l" rls of active i~y,tdi~r,l~ is an improvement over prior art systems since
less residue remains when such a system is used as a hard surface cleaner. The
feature of less residue is further shown by analyzing the o,i~"ldlion of the uptake
contours in Figures 1 a-b and 2a-b. Figures 1 a and 1 b show that in the ethylene glycol
monohexyl ether and diethylene glycol monohexyl ether systems the contours are
oriented largely towards the SLS-cosurfactant side. This means that oil solubilization
is increased by increasing the amount of cosurfactant and not the amount of
surfactant. Since the ~ol~ n capacity can be increased by i"~ a~i"g the
amount of the volatile component instead of a non-volatile surfactant, less residue is
left on a hard surface. It is noted however, that the contour orit",ldt;on may depend on
the chain length of the oil.
It should also be noted that Figure 1 a shows that at high levels of surfactant,
cosurfactant and dodecane, liquid crystals are formed.
FYAInOIP 2
Figure 3 shows the dodecane uptake capacity of a system containing
diethylene glycol monohexyl ether compared with a system containing diethylene
glycol monobutyl ether. In both cases, a mixture of Mg lauryl sulfate and Neodol 25-7
(a straight chain nonionic surfactant with 12-15 carbon atoms and 7 ethoxy groups,
available from Shell Chemical Co.) was used at a total concd"l,dlion of 6%. The
weight fraction of the Neodol 25-7 was varied from 0 to 1. The cosurfactant,
diethylene glycol monohexyl ether or diethylene glycol monobutyl ether was kept
constant at 3%. Perfume was added at a level of 0.8% in order to form the
microemulsion. Except at very high weight fractions of Neodol 25-7, the dodecaneuptake was si~u,llifiudlllly higher for diethylene glycol ",onoh~,~yl ether as cosurfactant
than for diethylene glycol monobutyl ether, the oil solubility being nearly doubled.
FYA~OIP 3
The sol~' ' ,9 pe,fu,,,,anc~ of the ethylene glycol ",onoht:,~yl ether and
diethylene glycol ",onoh~,~yl ether systems was next compared with ethylene glycol
monobutyl ether and diethylene glycol monobutyl ether where triolein is the oil to be
solll' " ' In these examples, microemulsions were preformed with dodecane as a
soll~ I,yd,ucd,uon and uptake capacities of triolein in these systems measured.
However, triolein uptake in systems without dodecane has also been measured.
Figures 4 and 5 show triolein uptake in two example ethylene glycol monohexyl
ether systems as a function of the amount of dodecane solll' ' ' The amount of
dodecane is l~pr~s~"t~,d as a percentage calculated by equation (1 ) given above.
The amount of triolein sol~ d was calculated by the equation:
~/O tnolei n = mR~ triolein soll Ihi j~P~1 x 1 00~/O (~)
mass sum brine, SLS, cosurfactant+dodecane
5 Figure 4 shows that in a composition of 5O/o of SLS, 5~/O ethylene glycol ",onoh~Ayl
ether, 90~/O brine with 1.4% dodecane solu' " ' (as defined in Equationl), 0.14%triolein (as defined by Equation2) may be 50lu " ' Figure 4 also shows that with a
higher conc~"l, -n of active iny,edie"l~ - 7.5~/O each of SLS and ethylene glycol
",onoheAyl ether, 85% brine with 1.4% dodecane 501~' " ' = 1.26% triolein may be10 sOIIl' " ' Figure 5 shows that triolein uptake in the diethylene glycol ",onoh~Ayl
ether system, where a co",po~iliun of 12.5% SLS, 12.5% diethylene glycol ""~noht:Ayl
ether, 75~/O brine can solubilize a maximum of 1.55% triolein when 3.6% dodecane is
presolubilized. In systems employing ethylene glycol monobutyl ether or diethylene
glycol monobutyl ether, NaCI brine, and SLS with colllr~ 'i~ 1S in the ranges
15 specified in Figures 4 and 5, no significant triolein uptake was measured. The fact that
the systems employing ethylene glycol monohexyl ether and diethylene glycol
",onoh~Ayl ether were able to solubilize significant quantities of triolein, while those
with ethylene glycol monobutyl ether and diethylene glycol monobutyl ether cannot
solubilize any triolein, attests to the superior perfu""dnce of the ethylene glycol~0 ",onoh~Ayl ether and diethylene glycol ",onoh~Ayl ether systems.
EY:ImrlP 4
In order to test grease cleaning per~(,r",al,ce, two prototype all-purpose cleaner
formulations were prepared and are shown below in Table 1 as co",, --. " ns A & B.
T~hlP 1 Co",~ n of Forml~l~c Tested
Material _ B
Mg Lauryl Sulfate 3.0 3.0
Neodol 25-7 3.0 3.0
Diethylene glycol mono butyl ether 3.0
Diethylene glycol mono hexyl ether 3.0
Perfume 0.8 0.8
Water q.s. q.s.
12
Figures 6 and 7 show a cu,,,udlison of the grease cleaning ability of formulae Aand B when used neat (undiluted) and diluted. When used neat, Formula B,
containing diethylene glycol ",onoh~,~yl ether, cleans siy"i~icd"lly faster than formula
A. When diluted, both formulae perform equally well. Thus, when used as a
cosurfactant, diethylene glycol monohexyl ether shows enhanced grease cleaning on
neat a" ' 'i~ 1 and equal cleaning upon dilution when compared with diethylene
glycol monobutyl ether.
ClP~nin,o Procedure
A mixture of 50~/O hard tallow and 50~/O soft tallow dyed with D&C Red #17 was
applied to new Formica tiles (15cm x 15cm) by spraying a ul-lu~u~um~ solution with an
air brush. For the Neat test, a 10% solution of the grease was used while for dilute, a
2~/3 solution was used. In both cases, a 0.01% solution of the dye was used. For Neat
cleaning, 1.0% of each formula was applied to sponges which were previously
saturated with tap water and wrung out. For diluted cleaning, sponges were saturated
with 1.2% solutions of the formulae in tap water. The sponges were placed in holders
and placed on a sled of a Gardner Abrader apparatus. Each sponge holder contained
270 9 of lead shot. The abrader was allowed to operate for the desired number ofstrokes and the percent ,ull~,_ldnc~ of the tile was measured. For neat,. the operation
was continued stopping after 1, 3, 5, 10, 20, 35 and 50 strokes. For dilute, thesponges and holders were removed after every 15 strokes so that the sponges could
be wrung out and ,~pl~"i~l1ed with solution.
The ~/0 cleaning was calculated according to the following ratio:
ClPRned tile reflPf~ ce-soiled tile reflPrt~nce x 100
Unsoiled tile ,~lle,,ldnce-soiled tile reflectance
An average of three readings was used for each test.
Although the invention has been described with a certain amount of
particularity, it is ulld~l~lood that the present disclosure of the preferred forms has
been made only by way of example and that numerous changes can be resorted to
without departing from the spirit and the scope of the invention.
